Erdosteine as a Novel Modulator of Surfactant Maturation: A Comparative Analysis With Dexamethasone and Betamethasone in a Preterm Rat Lung Model

Erdosteine as a Novel Modulator of Surfactant Maturation: A Comparative Analysis With Dexamethasone and Betamethasone in a Preterm Rat Lung Model | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Article Erdosteine as a Novel Modulator of Surfactant Maturation: A Comparative Analysis With Dexamethasone and Betamethasone in a Preterm Rat Lung Model Serife Ozlem GENC, Caglar YILDIZ, Mahmut SAHIN, Alper Serhat KUMRU, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8395257/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 10 You are reading this latest preprint version Abstract Background: Preterm birth remains a major contributor to neonatal morbidity, largely due to immature lung structure and insufficient surfactant production. This study evaluated the potential of erdosteine as an alternative or complementary agent to antenatal corticosteroids (ACS) by comparing its effects on lung maturation with dexamethasone (DEX) and betamethasone (BET) in a preterm rat model. Particular emphasis was placed on two anatomical compartments: the interstitial area and the bronchiolar epithelium. Methods: Preterm delivery was induced by cesarean section on gestational day 16 in Sprague–Dawley rats. Newborn pups were assigned to four groups: control, DEX, BET, and erdosteine (ERDO). Lung tissues collected on postnatal day 5 underwent histopathological evaluation and immunohistochemical analysis of Caspase-3, PCNA, ABCA3, SFTPA1, AQP5, and SP-B. Staining intensity was semi-quantitatively scored in both compartments. Results: DEX and BET produced lung histology that closely resembled normal tissue architecture, whereas ERDO resulted in only mild interstitial mononuclear infiltration. Caspase-3 and PCNA expression markedly increased in both compartments of the DEX and BET groups but remained low in ERDO and controls. ABCA3 expression was most pronounced in the ERDO group across both compartments (p < 0.001), surpassing even the corticosteroid groups. SFTPA1 was highest in the interstitial area of ERDO-treated pups, while bronchiolar epithelial staining was more evident in the control and DEX groups. AQP5 and SP-B did not show significant positivity in any group. Conclusions: Erdosteine demonstrated a supportive and biologically meaningful pattern of lung maturation, with reduced inflammation and balanced cellular turnover, accompanied by a notable increase in surfactant-related markers—particularly ABCA3. While not replicating all effects of antenatal corticosteroids, its favorable molecular profile and absence of corticosteroid-associated tissue alterations highlight its potential as a gentler, complementary approach to promoting pulmonary readiness in preterm neonates. These findings warrant further investigation in broader experimental and clinical settings. Health sciences/Diseases Health sciences/Medical research Biological sciences/Physiology Preterm birth antenatal corticosteroid erdosteine lung maturation surfactant proteins Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Background Preterm birth accounts for nearly 11% of all live births and remains a leading contributor to neonatal morbidity and mortality worldwide [ 1 , 2 ]. Respiratory distress syndrome, driven by inadequate lung maturation and surfactant deficiency, is one of the most critical complications associated with early delivery [ 3 ]. For decades, antenatal corticosteroids (ACS) have represented the cornerstone of perinatal management, effectively reducing respiratory distress syndrome by accelerating the structural and functional maturation of the fetal lung [ 4 ]. Their primary mechanism involves promoting type II pneumocyte differentiation and increasing expression of key surfactant proteins (SP-A, SP-B, SP-C) as well as ABCA3, a pivotal regulator of phospholipid transport and lamellar body formation [ 5 ]. Despite their well-documented respiratory benefits, concerns regarding the long-term systemic effects of ACS have intensified. A growing body of work suggests that prenatal glucocorticoid exposure may induce persistent developmental programming in extra-pulmonary organs—including alterations in the hypothalamic–pituitary–adrenal axis [ 6 – 8 ] and potential impacts on neurodevelopment and cardiometabolic pathways [ 9 ]. Experimental studies further demonstrate that prenatal dexamethasone can impair testicular barrier integrity, suppress testosterone production, and disrupt ovarian development, indicating a broader spectrum of glucocorticoid-related developmental toxicity [ 10 – 12 ]. These findings underscore the need for alternative or adjunctive agents capable of supporting lung maturation while minimizing systemic endocrine and developmental risks. Within this context, erdosteine has emerged as a biologically plausible candidate. A thiol-containing prodrug, erdosteine is metabolized to active free-sulfhydryl derivatives—particularly the M1 metabolite—conferring antioxidant, anti-inflammatory, and mucoregulatory properties [ 13 ]. Clinically, it is used in chronic obstructive pulmonary disease and upper respiratory infections, where it reduces mucus viscosity and mitigates oxidative stress [ 14 , 15 ]. Yet, despite its favorable safety profile and lung-directed antioxidant capacity, its role in fetal or neonatal lung maturation remains unexplored. Methods Study Design and Ethical Approval This controlled experimental study was designed to compare the effects of erdosteine with dexamethasone (DEX) and betamethasone (BET) on preterm lung maturation. All procedures were approved by the Sivas Cumhuriyet University Institutional Animal Care and Use Committee (Decision No: 658, dated 24.11.2023) and conducted in accordance with international guidelines for animal research. An a priori power analysis was not feasible due to the exploratory nature of the study; however, group sizes were consistent with previously published ACS–surfactant rat models, ensuring biological validity. Animals and Confirmation of Pregnancy Timed-pregnant Sprague–Dawley rats were obtained from the institutional breeding facility. Pregnancy was confirmed solely by the detection of a vaginal copulatory plug, following standard rodent reproductive assessment protocols. Animals were housed under controlled environmental conditions (22 ± 2°C, 50–60% relative humidity, 12-hour light–dark cycle) with ad libitum access to food and water. All husbandry procedures conformed to the Guide for the Care and Use of Laboratory Animals and adhered to AAALAC International standards. On gestational day 16, preterm delivery was induced by cesarean section under anesthesia. Immediately thereafter, pregnant rats were euthanized under deep anesthesia using an intraperitoneal injection of sodium pentobarbital (200 mg/kg). Adequate depth of anesthesia was confirmed by the absence of corneal and pedal withdrawal reflexes prior to euthanasia. This chemical method was selected in accordance with institutional animal care guidelines to ensure rapid and humane death. Experimental Groups and Randomization Newborn pups were randomly allocated into four groups: 1. Control DEX : postnatal dexamethasone BET : postnatal betamethasone ERDO : postnatal erdosteine To avoid litter-based clustering effects, no more than one pup per litter was assigned to each group. Group sizes ranged from 8 to 12 pups depending on litter availability. Drug Administration Corticosteroid Treatment Pups in the DEX and BET groups received: Dexamethasone : 0.2 mg/kg/day, intraperitoneal Betamethasone : 0.2 mg/kg/day, intraperitoneal These doses were selected based on validated neonatal glucocorticoid models of lung maturation. Erdosteine Treatment Pups in the ERDO group received: Erdosteine : 10 mg/kg/day, oral gavage This dose was chosen based on established respiratory safety data and preclinical efficacy reports. All treatments were administered once daily from postnatal day 0 to postnatal day 5. Tissue Collection On postnatal day 5, pups were euthanized with high-dose pentobarbital. Lungs were inflation-fixed with 10% neutral-buffered formalin, processed routinely, embedded in paraffin, and sectioned at a thickness of 5 µm for histopathological and immunohistochemical analyses. Histopathological Evaluation Hematoxylin and eosin (H&E) staining was performed on lung sections. A blinded pathologist evaluated: Alveolar structural maturation Interstitial thickness Degree of mononuclear inflammatory infiltration Overall architectural integrity A semi-quantitative scoring scale (0 = none, 1 = mild, 2 = moderate, 3 = severe) was applied. Representative micrographs are shown in Fig. 1 . Immunohistochemistry Immunohistochemical staining was conducted using antibodies against: Caspase-3 (apoptosis) PCNA (proliferation) ABCA3 (surfactant phospholipid transporter) SFTPA1 (surfactant protein A1) AQP5 (type I pneumocyte marker) SP-B (surfactant protein B) The primary antibodies used for immunohistochemistry, including manufacturer and catalog number, are summarized in Table 1 . Table 1 Antibodies Used in Immunohistochemistry Marker Manufacturer Catalog No. Caspase-3 ThermoFisher PA5-114687 PCNA Abcam ab29 ABCA3 Affbiotech DF9245 SFTPA1 Affbiotech DF7204 AQP5 Affbiotech AF5169 SP-B Affbiotech DF8615 Following deparaffinization and antigen retrieval (citrate buffer, pH 6.0), sections were incubated with primary antibodies overnight at 4°C. Detection was performed using Horseradish peroxidase -conjugated secondary antibodies and 3,3’-diaminobenzidine. Compartment-Specific Analysis Staining intensity was evaluated separately in: • Interstitial compartment • Bronchiolar epithelial compartment Quantitative analysis was performed using QuPath v0.6.0, and results were expressed as the percentage of positively stained cells. Statistical Analysis Data were analyzed using IBM SPSS Statistics for Windows, Version 20.0 (IBM Corp., Armonk, NY, USA) and GraphPad Prism 8 (GraphPad Software, Boston, MA, USA). • Histopathological scores: Kruskal–Wallis test, followed by Bonferroni-adjusted Mann–Whitney U pairwise comparisons. • Immunohistochemistry (% positive cells): One-Way ANOVA with Tukey’s post hoc test, after confirming normality (Shapiro–Wilk test) and homogeneity of variance (Levene’s test). A two-sided p < 0.05 was considered statistically significant. Results Histopathological and Immunohistochemical Findings Histopathological evaluation showed that the Control, DEX, and BET groups maintained near-normal alveolar architecture with thin septa and no significant inflammatory infiltration. The ERDO group displayed mild interstitial infiltration but retained overall lung structure, suggesting a limited inflammatory response (Fig. 1 ). Immunohistochemical analysis revealed distinct expression patterns across groups. Overall statistical comparisons showed significant differences for Caspase-3, PCNA, ABCA3, and SFTPA1 (p < 0.05), while AQP5 and SP-B were negative in all groups (Fig. 2 ). Caspase-3 and PCNA were minimally expressed in the Control and ERDO groups but were significantly higher in the DEX and BET groups, indicating increased apoptosis and proliferation due to glucocorticoid exposure (Figs. 3 and 4 ). ABCA3 was most strongly expressed in the ERDO group, followed by DEX, with lower levels in BET and Control (Fig. 5 ). SFTPA1 was more prominent in the interstitial compartment of the ERDO group, while DEX and Control had higher epithelial expression (Fig. 6 ). AQP5 and SP-B were not detected in any group, consistent with the expected low levels at this developmental stage (Figs. 7 and 8 ). Discussion Preterm birth–related respiratory distress syndrome remains a major cause of neonatal morbidity and mortality and is primarily driven by surfactant deficiency and structural immaturity of the lung. Antenatal corticosteroids are still the standard of care to accelerate fetal lung maturation and reduce early respiratory complications. However, concerns about possible long-term cardiometabolic or neurodevelopmental effects, especially with repeated or high-dose exposure, have renewed interest in alternative or adjunctive strategies that might support lung maturation with a more favourable safety profile [ 16 – 20 ]. In this preterm rat model, dexamethasone and betamethasone produced a nearly normal histological appearance, whereas erdosteine resulted in preserved alveolar structure with only mild interstitial mononuclear cell infiltration. This indicates that erdosteine does not exert harmful tissue effects but induces a modest inflammatory response. The minimal inflammation in the corticosteroid groups aligns with studies showing that antenatal betamethasone reduces inflammatory cell accumulation and stabilises alveolar structure [ 21 , 22 ]. Given that glucocorticoids suppress NF-κB–dependent cytokine release and leukocyte recruitment [ 23 ], the reduced inflammatory scores in DEX and BET are not unexpected. By contrast, the mild infiltration with erdosteine may reflect a more balanced immunomodulatory profile in which oxidative stress is attenuated without complete suppression of local defence mechanisms [ 13 , 14 , 24 ]. Caspase-3 expression was increased in both the interstitial and bronchiolar epithelium of the corticosteroid-treated groups, consistent with previous ovine and rodent studies reporting steroid-induced epithelial apoptosis and thinning of alveolar septa [ 22 , 25 ]. In contrast, caspase-3 positivity remained low in the erdosteine group, paralleling evidence that erdosteine and its active metabolite limit reactive oxygen species and mitigate mitochondrial stress–related apoptotic pathways [ 14 , 24 , 26 ]. These findings suggest that erdosteine may confer protection against excessive apoptosis during early lung development, in contrast to the more pronounced remodelling triggered by classical glucocorticoids. The PCNA expression pattern further supports this divergence. Dexamethasone showed the highest proliferative activity, followed by betamethasone, whereas erdosteine and control lungs exhibited lower levels. This is compatible with reports that glucocorticoids transiently enhance epithelial proliferation and differentiation before promoting maturation of alveolar structures [ 27 , 28 ]. The relatively modest PCNA positivity in the erdosteine group implies that it does not directly stimulate proliferation but may facilitate maturation through preservation of cellular integrity and redox balance—an effect that could support surfactant pathways without provoking excessive architectural remodelling. One of the most striking findings is the ABCA3 expression profile. ABCA3, a key ATP-binding cassette lipid transporter in type II pneumocytes, is essential for phospholipid import, lamellar body maturation and surfactant homeostasis. Experimental and clinical studies demonstrate that ABCA3 dysfunction impairs lamellar body biogenesis, alters surfactant lipid composition and compromises alveolar stability [ 29 – 32 ]. Loss-of-function ABCA3 variants are associated with lethal neonatal respiratory distress and interstitial lung disease, highlighting its central role in lung development [ 31 , 33 , 34 ]. Although corticosteroids are known to increase ABCA3 expression and lamellar body maturation in experimental settings [ 5 , 35 ], our data showed the highest ABCA3 staining in the erdosteine group across both interstitial and bronchiolar regions. This suggests that erdosteine may amplify surfactant-related lipid transport not only through pathways overlapping with glucocorticoid responsiveness but also via redox-sensitive mechanisms that preserve phospholipid-synthesising enzymes and membrane transporter activity. The parallel increase in interstitial and epithelial compartments supports a global enhancement of surfactant trafficking. SFTPA1 displayed a compartment-specific profile. Interstitial staining was most pronounced in the erdosteine group, while epithelial expression was higher in the control and DEX groups and lower in BET and ERDO. SFTPA1 is a major hydrophilic surfactant protein involved in surfactant structure, surface-tension regulation, pathogen opsonisation and immunomodulation [ 36 – 38 ]. Its expression increases during the late canalicular and saccular stages, and contemporary explant, organoid and epithelial models confirm glucocorticoid-driven upregulation of SP-A [ 39 – 42 ]. The distribution observed here suggests that erdosteine may preferentially enhance interstitial or stromal surfactant-related immunoregulation, whereas corticosteroids more strongly influence epithelial differentiation and secretion patterns. AQP5 and SP-B were immunonegative across all groups at postnatal day 5. This is consistent with developmental reports demonstrating that both markers increase closer to term and early postnatally, often remaining low at very early time points, particularly in immature lung models [ 43 – 45 ]. Thus, their absence likely reflects developmental stage rather than intervention-specific suppression. Taken together, these findings indicate that erdosteine supports preterm lung maturation in a manner partially overlapping with but distinct from classical corticosteroids. Erdosteine increased ABCA3 and interstitial SFTPA1 expression while maintaining low apoptosis and modest proliferation, accompanied by preserved lung architecture. Dexamethasone and betamethasone induced stronger apoptotic and proliferative responses, leading to near-normal histology but relatively lower ABCA3 levels than erdosteine. These patterns raise the hypothesis that thiol-based antioxidant therapy may complement or, in selected circumstances, partially substitute glucocorticoids in supporting surfactant biogenesis while potentially reducing systemic programming effects. Nevertheless, such strategies require rigorous evaluation of timing, dose and interaction with standard ACS regimens, ideally in clinically relevant models and, ultimately, in human trials. This study has several limitations. First, the sample size was modest and analyses were conducted at a single early postnatal time point, precluding assessment of longer-term structural or functional outcomes. Second, the immunohistochemical approach was semi-quantitative and targeted selected markers; molecular analyses and functional evaluations (lung mechanics, gas exchange) were not performed. Third, only one dosing regimen of each intervention was tested, and dose–response or combination protocols were not explored. Finally, systemic effects on other organs—which are pertinent to the broader safety considerations of ACS and antioxidant therapies—were beyond the study’s scope. Despite these limitations, this study provides initial experimental evidence that erdosteine can modulate key surfactant-regulatory markers such as ABCA3 and SFTPA1 in the preterm lung, with an apoptosis–proliferation profile distinct from dexamethasone and betamethasone. These results support further investigation of erdosteine as a potential adjunct or alternative to antenatal corticosteroids, particularly in models integrating functional respiratory outcomes and long-term follow-up. Conclusions In this preterm rat model, erdosteine exhibited a maturation profile that was clearly distinct from that of dexamethasone and betamethasone. While classical antenatal corticosteroids generated robust apoptotic and proliferative activity consistent with accelerated structural maturation, erdosteine produced minimal apoptosis, preserved alveolar architecture and a comparatively modest proliferative response. Most notably, erdosteine markedly increased ABCA3 expression and enhanced interstitial SFTPA1 staining, suggesting a favourable impact on surfactant-related lipid transport and innate immune readiness. These effects emerged without the degree of tissue remodelling observed in the corticosteroid groups. Taken together, the data indicate that thiol-based antioxidant therapy may support surfactant biogenesis and early lung maturation through mechanisms partially overlapping with, yet biologically distinct from, glucocorticoid-driven pathways. Although the present findings are limited by sample size, a single postnatal time point and the absence of functional respiratory assessments, they provide preliminary experimental evidence that erdosteine could serve as an adjunctive or, under selected conditions, a partial alternative to antenatal corticosteroids. Future studies incorporating dose–response analyses, combined regimens, long-term structural and functional outcomes, and translationally relevant models will be essential to define the therapeutic potential and safety profile of erdosteine in the context of preterm lung maturation. Abbreviations ABCA3 ATP-binding cassette subfamily A member 3 ACS Antenatal corticosteroids AQP5 Aquaporin-5 BET Betamethasone DEX Dexamethasone ERDO Erdosteine H&E Hematoxylin and eosin IHC Immunohistochemistry PCNA Proliferating cell nuclear antigen SFTPA1 Surfactant protein A1 SP-A Surfactant protein A SP-B Surfactant protein B SPSS Statistical Package for the Social Sciences Declarations Author Contributions S.O.G. conducted the conceptualization and study design, supervised the research, performed histopathological evaluations, interpreted the data, drafted the manuscript, and approved the final version. C.Y. contributed to the methodology, supervised the study, and critically revised the manuscript. M.S. performed the animal procedures, administered the treatments, developed the experimental model, and collected the data. A.S.K. carried out the laboratory processing, conducted the immunohistochemical analyses, and contributed to data acquisition. M.O. performed the histopathological examinations, scoring, validation, and visualization. All authors read and approved the final manuscript. Funding Statement This study was supported by the Sivas Cumhuriyet University Scientific Research Projects Commission (CUBAP) under project number T-2024-1043. Acknowledgment The authors thank the Sivas Cumhuriyet University Experimental Animal Research Center staff for their technical assistance during animal care and procedures. Ethics Approval and Consent to Participate This study was approved by the Sivas Cumhuriyet University Animal Experiments Local Ethics Committee (HADYEK) with the decision dated 24.11.2023 and numbered 658. All procedures were conducted in accordance with institutional guidelines and the ARRIVE recommendations. Competing Interests The authors declare that they have no competing interests. Data Availability Statement The datasets generated and analyzed during the current study are available from the corresponding author on reasonable request. Consent to Publish Declaration Not applicable. References Chawanpaiboon, S. et al. Global, regional, and national estimates of levels of preterm birth in 2014: a systematic review and modelling analysis. Lancet Glob Health . 7 (1), e37–e46. 10.1016/S2214-109X(18)30451-0 (2019). Ciapponi, A. et al. Dexamethasone versus betamethasone for preterm birth: a systematic review and network meta-analysis. Am. J. Obstet. Gynecol. MFM . 3 (3), 100312. 10.1016/j.ajogmf.2021.100312 (2021). Stoll, B. J. et al. Trends in care practices, morbidity, and mortality of extremely preterm neonates, 1993–2012. JAMA 314 (10), 1039–1051. 10.1001/jama.2015.10244 (2015). Roberts, D., Brown, J., Medley, N. & Dalziel, S. R. Antenatal corticosteroids for accelerating fetal lung maturation for women at risk of preterm birth. Cochrane Database Syst. Rev. (3), CD004454. 10.1002/14651858.CD004454.pub3 (2017). Meyer, N., Kallapur, S. G., Ikegami, M. & Jobe, A. H. Antenatal corticosteroids and surfactant protein expression in preterm lung development. Front. Physiol. 11 , 565213. 10.3389/fphys.2020.565213 (2020). Matthews, S. G. Antenatal glucocorticoids and programming of the developing hypothalamo–pituitary–adrenal axis. Pediatr. Res. 47 (1), 4–13. 10.1203/00006450-200001000-00002 (2000). Seckl, J. R. & Meaney, M. J. Glucocorticoid programming. Ann. N Y Acad. Sci. 1032 , 63–84. 10.1196/annals.1314.006 (2004). Moisiadis, V. G. & Matthews, S. G. Glucocorticoids and fetal programming part 1: Outcomes. Nat. Rev. Endocrinol. 10 (7), 391–402. 10.1038/nrendo.2014.73 (2014). Carson, C. et al. Association between antenatal corticosteroids and risk of serious neonatal outcomes: population-based cohort study. BMJ 382 , e075835. 10.1136/bmj-2023-075835 (2023). Liu, M. et al. Prenatal dexamethasone exposure programs the development and function of the testis. Reprod. Fertil. Dev. 34 (19), RFD20164. 10.1071/RD20164 (2022). Liu, Y. et al. Prenatal dexamethasone exposure impairs rat blood–testis barrier and sperm quality. Acta Pharmacol. Sin . 10.1038/s41401-024-01244-5 (2024). Ristić, N. et al. Prenatal dexamethasone and ovary development: a structural study in the rat. Toxicol. Appl. Pharmacol. 10.1016/j.taap.2020.115345 (2021). Cazzola, M., Rogliani, P., Calzetta, L. & Matera, M. G. Multifaceted beneficial effects of erdosteine: more than a mucolytic agent. Drugs 80 (15), 1605–1617. 10.1007/s40265-020-01412-x (2020). Dal Negro, R. W. & Visconti, M. Erdosteine reduces the exercise-induced oxidative stress in patients with severe COPD: results of a placebo-controlled trial. Pulm Pharmacol. Ther. 41 , 48–51. 10.1016/j.pupt.2016.09.007 (2016). Pisi, R. & Chetta, A. Erdosteine in children and adults with bronchiectasis: efficacy, safety and future perspectives. Multidiscip Respir Med. 19 (1), 6. 10.1186/s40248-024-00221-7 (2024). Kelly, B. A. et al. Antenatal corticosteroids and offspring cardiovascular health: a review. Placenta 97 , 65–72. 10.1016/j.placenta.2020.06.014 (2020). Murphy, K. E. et al. Multiple courses of antenatal corticosteroids for preterm birth: a systematic review and meta-analysis. BJOG 128 (8), 1357–1367. 10.1111/1471-0528.16607 (2021). Sultana, S. et al. Long-term outcomes of antenatal corticosteroids for preterm birth: a systematic review. PLOS Glob Public. Health . 5 (3), e0004575. 10.1371/journal.pgph.0004575 (2025). Liauw, J. et al. Antenatal corticosteroids and child neurodevelopment: a systematic review and meta-analysis. Obstet. Gynecol. 146 (5), 360–376. 10.1097/AOG.0000000000005950 (2025). Tosto, V. et al. Antenatal corticosteroids in early and late fetal growth restriction. J. Clin. Med. 14 (14), 4876. 10.3390/jcm14144876 (2025). Ikegami, M. et al. Betamethasone treatment of fetal sheep lung: effects on lung compliance, surfactant, and morphology. Am. J. Physiol. Lung Cell. Mol. Physiol. 272 (5), L915–L924. 10.1152/ajplung.1997.272.5.L915 (1997). Jobe, A. H. et al. Repeated antenatal corticosteroid treatments in preterm sheep: lung morphology and morphometry. Pediatr. Res. 43 (1), 31–37. 10.1203/00006450-199801000-00006 (1998). Rhen, T. & Cidlowski, J. A. Antiinflammatory action of glucocorticoids—new mechanisms for old drugs. N Engl. J. Med. 353 (16), 1711–1723. 10.1056/NEJMra050541 (2005). Santus, P., Strizzi, S., Danzo, F., Biasin, M. & Trabattoni, D. Antiviral and immunomodulatory activity of erdosteine in human respiratory epithelial cells infected with respiratory viruses. Pathogens 14 (4), 388. 10.3390/pathogens14040388 (2025). Kallapur, S. G., Jobe, A. H. & Ikegami, M. Increased alveolar cell apoptosis and decreased epithelial proliferation after fetal exposure to corticosteroids in sheep. Am. J. Physiol. Lung Cell. Mol. Physiol. 292 (1), L92–L101. 10.1152/ajplung.00286.2006 (2007). Moretti, M. & Marchioni, C. F. An overview of erdosteine antioxidant activity in experimental research. Curr. Drug Targets . 8 (1), 81–88. 10.1016/j.phrs.2006.12.006 (2007). O’Brodovich, H. M. et al. Glucocorticoid regulation of lung epithelial ion transport and development. Am. J. Physiol. Lung Cell. Mol. Physiol. 284 (4), L595–L604. 10.1152/ajplung.00328.2002 (2003). Wang, Y. et al. Glucocorticoid regulation of cell proliferation and differentiation in developing lung. J. Endocrinol. 181 (1), 33–44. 10.1677/joe.0.1810033 (2004). Whitsett, J. A. & Weaver, T. E. Alveolar development and disease. Annu. Rev. Physiol. 77 , 493–515. 10.1146/annurev-physiol-021014-071842 (2015). Ban, N. et al. ABCA3 as a lipid transporter in lung lamellar bodies. J. Biol. Chem. 282 (7), 4321–4329. 10.1074/jbc.M611767200 (2007). Shulenin, S. et al. ABCA3 gene mutations in newborns with fatal surfactant deficiency. N Engl. J. Med. 350 (13), 1296–1303. 10.1056/NEJMoa032178 (2004). Wambach, J. A. et al. Genotype–phenotype correlations for ABCA3 mutations in infants and children with diffuse lung disease. Am. J. Respir Crit. Care Med. 189 (12), 1538–1543. 10.1164/rccm.201402-0342OC (2014). Nolan, J., Rodgers, J. & Mackintosh, J. A. ABCA3 Surfactant-Related Gene Variant Associated Interstitial Lung Disease in Adults: A Case Series and Review of the Literature. Respirol. Case Rep. 13 (8), e70304. 10.1002/rcr2.70304 (2025). Nogee, L. M., deMello, D. E., Dehner, L. P. & Colten, H. R. Deficiency of pulmonary surfactant protein A in congenital alveolar proteinosis. J. Clin. Invest. 91 (2), 842–847. 10.1172/JCI116267 (1993). Yoshida, I. et al. Expression of ABCA3, a causative gene for fatal surfactant deficiency, is up-regulated by glucocorticoids in lung alveolar type II cells. Biochem. Biophys. Res. Commun. 323 (2), 547–555. 10.1016/j.bbrc.2004.08.133 (2004). Thorenoor, N., Umstead, T. M., Zhang, X., Phelps, D. S. & Floros, J. Survival of Surfactant Protein-A1 and SP-A2 transgenic mice after Klebsiella pneumoniae infection exhibits sex-, gene- and variant-specific differences. Front. Immunol. 9 , 2404. 10.3389/fimmu.2018.02404 (2018). Floros, J. et al. Human surfactant protein SP-A1 and SP-A2 variants differentially affect the alveolar microenvironment and innate immune responses. Front. Immunol. 12 , 681639. 10.3389/fimmu.2021.681639 (2021). Depicolzuane, L., Phelps, D. S. & Floros, J. Surfactant protein A function: knowledge gained from SP-A knockout mice. Front. Pediatr. 9 , 799693DOI. 10.3389/fped.2021.799693 (2022). Jin, N. et al. Dexamethasone enhances surfactant protein expression in alveolar epithelial cells via MAPK and glucocorticoid receptor pathways. Am. J. Physiol. Lung Cell. Mol. Physiol. 314 (4), L615–L624. 10.1152/ajplung.00310.2017 (2018). Lin, S. et al. Dexamethasone promotes maturation of human fetal lung explants with increased SP-A and SP-B expression. J. Matern Fetal Neonatal Med. 30 (3), 322–329. 10.3109/14767058.2016.1169528 (2017). Sanchez-Esteban, J. et al. Mechanical stretch and glucocorticoids synergistically upregulate surfactant protein A in developing lung cells. Pediatr. Res. 85 (3), 361–368. 10.1038/s41390-018-0259-5 (2019). Alysandratos, K. D. et al. Glucocorticoid exposure promotes alveolar epithelial maturation and increases expression of surfactant proteins in human lung organoids. Stem Cell. Rep. 16 (12), 3000–3015. 10.1016/j.stemcr.2021.10.009 (2021). Ramírez, R. J. et al. Transepithelial sodium transport and lung fluid balance are regulated by alveolar type I cell differentiation. Am. J. Physiol. Lung Cell. Mol. Physiol. 278 (4), L659–L666. 10.1152/ajplung.2000.278.4.L659 (2000). Xu, J. et al. Developmental regulation of aquaporin-5 expression in perinatal mouse lung. Pediatr. Res. 66 (4), 371–377. 10.1203/PDR.0b013e3181b45592 (2009). Yadav, A. et al. Hyperoxia disrupts aquaporin-5 expression and alveolar epithelial maturation in the neonatal lung. Am. J. Physiol. Lung Cell. Mol. Physiol. 318 (4), L645–L658. 10.1152/ajplung.00530.2019 (2020). Additional Declarations No competing interests reported. Cite Share Download PDF Status: Under Review Version 1 posted Editorial decision: Revision requested 20 Feb, 2026 Reviews received at journal 05 Feb, 2026 Reviews received at journal 29 Jan, 2026 Reviewers agreed at journal 26 Jan, 2026 Reviewers agreed at journal 24 Jan, 2026 Reviewers invited by journal 21 Jan, 2026 Editor assigned by journal 15 Jan, 2026 Editor invited by journal 24 Dec, 2025 Submission checks completed at journal 22 Dec, 2025 First submitted to journal 22 Dec, 2025 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-8395257","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":578992254,"identity":"7b38ab23-c9ac-442f-9f44-2eb6844d73dd","order_by":0,"name":"Serife Ozlem GENC","email":"data:image/png;base64,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","orcid":"","institution":"Sivas Cumhuriyet University","correspondingAuthor":true,"prefix":"","firstName":"Serife","middleName":"Ozlem","lastName":"GENC","suffix":""},{"id":578992258,"identity":"f7eed180-4030-40b7-b182-e21a0081cd48","order_by":1,"name":"Caglar YILDIZ","email":"","orcid":"","institution":"Sivas Cumhuriyet University","correspondingAuthor":false,"prefix":"","firstName":"Caglar","middleName":"","lastName":"YILDIZ","suffix":""},{"id":578992262,"identity":"cda796a1-1e05-4d78-b4e4-9e988196cdf4","order_by":2,"name":"Mahmut SAHIN","email":"","orcid":"","institution":"Sivas Cumhuriyet University","correspondingAuthor":false,"prefix":"","firstName":"Mahmut","middleName":"","lastName":"SAHIN","suffix":""},{"id":578992265,"identity":"9103a717-755d-4135-ac53-2c8334db4273","order_by":3,"name":"Alper Serhat KUMRU","email":"","orcid":"","institution":"Sivas Cumhuriyet University","correspondingAuthor":false,"prefix":"","firstName":"Alper","middleName":"Serhat","lastName":"KUMRU","suffix":""},{"id":578992268,"identity":"68693bc7-d0e5-4f7c-bea3-026ad72bcaab","order_by":4,"name":"Mustafa OZKARACA","email":"","orcid":"","institution":"Sivas Cumhuriyet University","correspondingAuthor":false,"prefix":"","firstName":"Mustafa","middleName":"","lastName":"OZKARACA","suffix":""}],"badges":[],"createdAt":"2025-12-18 12:08:37","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-8395257/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-8395257/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":101171131,"identity":"ae4c41ad-663c-4b40-8625-85ecc33e5f69","added_by":"auto","created_at":"2026-01-27 00:07:19","extension":"docx","order_by":0,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":3435445,"visible":true,"origin":"","legend":"","description":"","filename":"ManuscriptErdoChecked.docx","url":"https://assets-eu.researchsquare.com/files/rs-8395257/v1/e45b9591a4a23d3be7ed07fa.docx"},{"id":101171119,"identity":"b008ed30-ad3e-41b5-aef8-5895d0ec7cb0","added_by":"auto","created_at":"2026-01-27 00:07:18","extension":"json","order_by":1,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":7956,"visible":true,"origin":"","legend":"","description":"","filename":"fc9c3b07e0f347a7bd41750d533fbe23.json","url":"https://assets-eu.researchsquare.com/files/rs-8395257/v1/a5c78e4b5049a942a64351f6.json"},{"id":101171121,"identity":"d647a1ad-ebba-444b-813a-0b4c2d0f7e03","added_by":"auto","created_at":"2026-01-27 00:07:18","extension":"xml","order_by":2,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":102846,"visible":true,"origin":"","legend":"","description":"","filename":"fc9c3b07e0f347a7bd41750d533fbe231enriched.xml","url":"https://assets-eu.researchsquare.com/files/rs-8395257/v1/0128b403a31129e4ac73e88c.xml"},{"id":101171123,"identity":"8e76db01-748c-447f-a2fd-802ffa91c631","added_by":"auto","created_at":"2026-01-27 00:07:18","extension":"png","order_by":11,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":216275,"visible":true,"origin":"","legend":"","description":"","filename":"Onlinefloatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-8395257/v1/c3f020ef9477c074e3e0a8a0.png"},{"id":101171130,"identity":"28bf0325-47de-406c-9bd4-f63565e58acd","added_by":"auto","created_at":"2026-01-27 00:07:19","extension":"png","order_by":12,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":20741,"visible":true,"origin":"","legend":"","description":"","filename":"Onlinefloatimage2.png","url":"https://assets-eu.researchsquare.com/files/rs-8395257/v1/85a5cfffb7b2d98eda3a5782.png"},{"id":101171132,"identity":"b2c74ed2-556d-407c-bae8-c69d321607e5","added_by":"auto","created_at":"2026-01-27 00:07:19","extension":"png","order_by":13,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":307548,"visible":true,"origin":"","legend":"","description":"","filename":"Onlinefloatimage3.png","url":"https://assets-eu.researchsquare.com/files/rs-8395257/v1/90a04ed4c47892406b8c23fa.png"},{"id":101171136,"identity":"8ce1004f-40bd-4a34-bef3-d8504a82e68c","added_by":"auto","created_at":"2026-01-27 00:07:19","extension":"png","order_by":14,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":287786,"visible":true,"origin":"","legend":"","description":"","filename":"Onlinefloatimage4.png","url":"https://assets-eu.researchsquare.com/files/rs-8395257/v1/afa6f502f15b7aacbbd571e2.png"},{"id":101171134,"identity":"00132c74-33be-422a-9c47-342bfedd7b58","added_by":"auto","created_at":"2026-01-27 00:07:19","extension":"png","order_by":15,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":366127,"visible":true,"origin":"","legend":"","description":"","filename":"Onlinefloatimage5.png","url":"https://assets-eu.researchsquare.com/files/rs-8395257/v1/420c4a4b58c8e739327de521.png"},{"id":101206217,"identity":"e50f2337-72a1-4951-8a19-5719151f1608","added_by":"auto","created_at":"2026-01-27 09:55:40","extension":"png","order_by":16,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":375994,"visible":true,"origin":"","legend":"","description":"","filename":"Onlinefloatimage6.png","url":"https://assets-eu.researchsquare.com/files/rs-8395257/v1/2c2aa31146f04856441f55fc.png"},{"id":101171137,"identity":"9d7d6bc9-8a4c-4447-a192-68ecef1ca700","added_by":"auto","created_at":"2026-01-27 00:07:19","extension":"png","order_by":17,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":286383,"visible":true,"origin":"","legend":"","description":"","filename":"Onlinefloatimage7.png","url":"https://assets-eu.researchsquare.com/files/rs-8395257/v1/04aa3d8feb99a059cc9e8abb.png"},{"id":101171138,"identity":"68e88e42-2107-4ab5-9001-755200cd1d73","added_by":"auto","created_at":"2026-01-27 00:07:19","extension":"png","order_by":18,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":300716,"visible":true,"origin":"","legend":"","description":"","filename":"Onlinefloatimage8.png","url":"https://assets-eu.researchsquare.com/files/rs-8395257/v1/4356f7cff2d0bc33af014d60.png"},{"id":101171139,"identity":"17d61611-40c0-41f1-9a01-cda45e2b8636","added_by":"auto","created_at":"2026-01-27 00:07:19","extension":"xml","order_by":19,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":100968,"visible":true,"origin":"","legend":"","description":"","filename":"fc9c3b07e0f347a7bd41750d533fbe231structuring.xml","url":"https://assets-eu.researchsquare.com/files/rs-8395257/v1/39e2dc3e629ee11c0d3c7e1a.xml"},{"id":101207068,"identity":"1d2ae22c-83c5-4eea-8fd8-65c2d56152cf","added_by":"auto","created_at":"2026-01-27 09:57:15","extension":"html","order_by":20,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":116385,"visible":true,"origin":"","legend":"","description":"","filename":"earlyproof.html","url":"https://assets-eu.researchsquare.com/files/rs-8395257/v1/ff6d021b6b29c644b7b8a2f2.html"},{"id":101171120,"identity":"bf27de02-e972-46d1-b884-a7150dfd82bc","added_by":"auto","created_at":"2026-01-27 00:07:18","extension":"jpeg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":360476,"visible":true,"origin":"","legend":"\u003cp\u003eRepresentative H\u0026amp;E-stained sections of bronchiolar tissue from Control (A), ERDO (B), BET (C), and DEX (D) groups. Normal histological morphology is preserved in all groups except ERDO, which shows mild interstitial mononuclear cell infiltration. Scale 20 µm.\u003c/p\u003e","description":"","filename":"floatimage1.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-8395257/v1/335c09818678f045de1fd2e5.jpeg"},{"id":101206569,"identity":"a8e7eaa7-92b6-492c-b2d6-2536e1a2b5b0","added_by":"auto","created_at":"2026-01-27 09:56:29","extension":"jpeg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":84501,"visible":true,"origin":"","legend":"\u003cp\u003eComparative statistical analysis of immunohistochemical markers (Caspase-3, PCNA, ABCA3, SFTPA1, AQP5, SP-B). Significant intergroup differences are indicated by *, **, ***, #, ##; ns: not significant.\u003c/p\u003e","description":"","filename":"floatimage2.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-8395257/v1/af1a096b1bec1738041b2f31.jpeg"},{"id":102745169,"identity":"e0cd2dd6-378e-4552-905a-6403e4248554","added_by":"auto","created_at":"2026-02-16 08:40:29","extension":"jpeg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":482331,"visible":true,"origin":"","legend":"\u003cp\u003eCaspase-3 immunoreactivity across groups. Arrows indicate positively stained regions. Bronchiolar sections; IHC; scale bar: 20 µm.\u003c/p\u003e","description":"","filename":"floatimage3.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-8395257/v1/a20211cc65f09518b1a293fb.jpeg"},{"id":101206796,"identity":"0df523bf-5ba8-49fa-ad9d-83c7f79c1331","added_by":"auto","created_at":"2026-01-27 09:56:45","extension":"jpeg","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":456495,"visible":true,"origin":"","legend":"\u003cp\u003ePCNA immunoreactivity showing differential proliferative activity among groups. Arrows denote PCNA-positive nuclei. Scale bar: 20 µm\u003c/p\u003e","description":"","filename":"floatimage4.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-8395257/v1/064c5899d65e70bb9cfef67c.jpeg"},{"id":101171125,"identity":"1a4802e7-74ec-4a87-ae36-c085a97fff49","added_by":"auto","created_at":"2026-01-27 00:07:18","extension":"jpeg","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":552481,"visible":true,"origin":"","legend":"\u003cp\u003eABCA3 immunostaining demonstrating marked interstitial and epithelial expression in the ERDO group. Scale bar: 20 µm.\u003c/p\u003e","description":"","filename":"floatimage5.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-8395257/v1/a5edb5ffc1b9127cfdca28eb.jpeg"},{"id":101171127,"identity":"8abaa7c5-f6b5-47df-82b9-2c290d19492e","added_by":"auto","created_at":"2026-01-27 00:07:18","extension":"jpeg","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":551690,"visible":true,"origin":"","legend":"\u003cp\u003eSFTPA1 immunostaining showing group-specific differences in interstitial and epithelial compartments. Scale bar: 20 µm.\u003c/p\u003e","description":"","filename":"floatimage6.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-8395257/v1/2317a7f7b81e06c4045f19fc.jpeg"},{"id":101206575,"identity":"77268c0d-8db6-4de2-9250-8a7d03c6ca1e","added_by":"auto","created_at":"2026-01-27 09:56:30","extension":"jpeg","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":476382,"visible":true,"origin":"","legend":"\u003cp\u003eAQP5 immunostaining in bronchiolar and interstitial regions across all experimental groups. No specific AQP5 expression was detected in any group, consistent with the low developmental expression of AQP5 in preterm rat lungs at P5. Scale bar: 20 µm.\u003c/p\u003e","description":"","filename":"floatimage7.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-8395257/v1/7440ea7310a445f993dde49b.jpeg"},{"id":101206502,"identity":"897f02ef-a98f-4f1b-98e4-00dc6d66f5a9","added_by":"auto","created_at":"2026-01-27 09:56:23","extension":"jpeg","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":468892,"visible":true,"origin":"","legend":"\u003cp\u003eSP-B immunostaining in bronchiolar and interstitial compartments of the neonatal lung. All groups demonstrated complete immunonegativity for SP-B, reflecting the expected immaturity of surfactant protein B expression in early postnatal lungs. Scale bar 20 µm.\u003c/p\u003e","description":"","filename":"floatimage8.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-8395257/v1/a3000a8223956ccc58d60afb.jpeg"},{"id":102751326,"identity":"6ecf9e7e-a20f-4d0f-9b9c-f3719089c978","added_by":"auto","created_at":"2026-02-16 09:25:12","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":4338177,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8395257/v1/0f10912b-dc63-4816-9ea5-2ce74621a84e.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Erdosteine as a Novel Modulator of Surfactant Maturation: A Comparative Analysis With Dexamethasone and Betamethasone in a Preterm Rat Lung Model","fulltext":[{"header":"Background","content":"\u003cp\u003ePreterm birth accounts for nearly 11% of all live births and remains a leading contributor to neonatal morbidity and mortality worldwide [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. Respiratory distress syndrome, driven by inadequate lung maturation and surfactant deficiency, is one of the most critical complications associated with early delivery [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. For decades, antenatal corticosteroids (ACS) have represented the cornerstone of perinatal management, effectively reducing respiratory distress syndrome by accelerating the structural and functional maturation of the fetal lung [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. Their primary mechanism involves promoting type II pneumocyte differentiation and increasing expression of key surfactant proteins (SP-A, SP-B, SP-C) as well as ABCA3, a pivotal regulator of phospholipid transport and lamellar body formation [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eDespite their well-documented respiratory benefits, concerns regarding the long-term systemic effects of ACS have intensified. A growing body of work suggests that prenatal glucocorticoid exposure may induce persistent developmental programming in extra-pulmonary organs\u0026mdash;including alterations in the hypothalamic\u0026ndash;pituitary\u0026ndash;adrenal axis [\u003cspan additionalcitationids=\"CR7\" citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e] and potential impacts on neurodevelopment and cardiometabolic pathways [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. Experimental studies further demonstrate that prenatal dexamethasone can impair testicular barrier integrity, suppress testosterone production, and disrupt ovarian development, indicating a broader spectrum of glucocorticoid-related developmental toxicity [\u003cspan additionalcitationids=\"CR11\" citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. These findings underscore the need for alternative or adjunctive agents capable of supporting lung maturation while minimizing systemic endocrine and developmental risks.\u003c/p\u003e \u003cp\u003eWithin this context, erdosteine has emerged as a biologically plausible candidate. A thiol-containing prodrug, erdosteine is metabolized to active free-sulfhydryl derivatives\u0026mdash;particularly the M1 metabolite\u0026mdash;conferring antioxidant, anti-inflammatory, and mucoregulatory properties [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. Clinically, it is used in chronic obstructive pulmonary disease and upper respiratory infections, where it reduces mucus viscosity and mitigates oxidative stress [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e, \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. Yet, despite its favorable safety profile and lung-directed antioxidant capacity, its role in fetal or neonatal lung maturation remains unexplored.\u003c/p\u003e"},{"header":"Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eStudy Design and Ethical Approval\u003c/h2\u003e \u003cp\u003eThis controlled experimental study was designed to compare the effects of erdosteine with dexamethasone (DEX) and betamethasone (BET) on preterm lung maturation. All procedures were approved by the Sivas Cumhuriyet University Institutional Animal Care and Use Committee (Decision No: 658, dated 24.11.2023) and conducted in accordance with international guidelines for animal research.\u003c/p\u003e \u003cp\u003eAn a priori power analysis was not feasible due to the exploratory nature of the study; however, group sizes were consistent with previously published ACS\u0026ndash;surfactant rat models, ensuring biological validity.\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eAnimals and Confirmation of Pregnancy\u003c/h3\u003e\n\u003cp\u003eTimed-pregnant Sprague\u0026ndash;Dawley rats were obtained from the institutional breeding facility. Pregnancy was confirmed solely by the detection of a vaginal copulatory plug, following standard rodent reproductive assessment protocols.\u003c/p\u003e \u003cp\u003eAnimals were housed under controlled environmental conditions (22\u0026thinsp;\u0026plusmn;\u0026thinsp;2\u0026deg;C, 50\u0026ndash;60% relative humidity, 12-hour light\u0026ndash;dark cycle) with ad libitum access to food and water.\u003c/p\u003e \u003cp\u003e All husbandry procedures conformed to the Guide for the Care and Use of Laboratory Animals and adhered to AAALAC International standards.\u003c/p\u003e \u003cp\u003eOn gestational day 16, preterm delivery was induced by cesarean section under anesthesia. Immediately thereafter, pregnant rats were euthanized under deep anesthesia using an intraperitoneal injection of sodium pentobarbital (200 mg/kg). Adequate depth of anesthesia was confirmed by the absence of corneal and pedal withdrawal reflexes prior to euthanasia. This chemical method was selected in accordance with institutional animal care guidelines to ensure rapid and humane death.\u003c/p\u003e\n\u003ch3\u003eExperimental Groups and Randomization\u003c/h3\u003e\n\u003cp\u003eNewborn pups were randomly allocated into four groups:\u003c/p\u003e\n\u003ch3\u003e1. Control\u003c/h3\u003e\n\u003cp\u003e \u003col\u003e \u003cspan\u003e \u003cli\u003e \u003cp\u003e \u003cb\u003eDEX\u003c/b\u003e: postnatal dexamethasone\u003c/p\u003e \u003c/li\u003e \u003c/span\u003e \u003cspan\u003e \u003cli\u003e \u003cp\u003e \u003cb\u003eBET\u003c/b\u003e: postnatal betamethasone\u003c/p\u003e \u003c/li\u003e \u003c/span\u003e \u003cspan\u003e \u003cli\u003e \u003cp\u003e \u003cb\u003eERDO\u003c/b\u003e: postnatal erdosteine\u003c/p\u003e \u003c/li\u003e \u003c/span\u003e \u003c/ol\u003e \u003c/p\u003e \u003cp\u003eTo avoid litter-based clustering effects, no more than one pup per litter was assigned to each group. Group sizes ranged from 8 to 12 pups depending on litter availability.\u003c/p\u003e\n\u003ch3\u003eDrug Administration\u003c/h3\u003e\n\u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003eCorticosteroid Treatment\u003c/h2\u003e \u003cp\u003ePups in the DEX and BET groups received:\u003c/p\u003e \u003cp\u003e \u003cul\u003e \u003cli\u003e \u003cp\u003e \u003cb\u003eDexamethasone\u003c/b\u003e: 0.2 mg/kg/day, intraperitoneal\u003c/p\u003e \u003c/li\u003e \u003cli\u003e \u003cp\u003e \u003cb\u003eBetamethasone\u003c/b\u003e: 0.2 mg/kg/day, intraperitoneal\u003c/p\u003e \u003c/li\u003e \u003c/ul\u003e \u003c/p\u003e \u003cp\u003eThese doses were selected based on validated neonatal glucocorticoid models of lung maturation.\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eErdosteine Treatment\u003c/h3\u003e\n\u003cp\u003ePups in the ERDO group received:\u003c/p\u003e \u003cp\u003e \u003cul\u003e \u003cli\u003e \u003cp\u003e \u003cb\u003eErdosteine\u003c/b\u003e: 10 mg/kg/day, oral gavage\u003c/p\u003e \u003c/li\u003e \u003c/ul\u003e \u003c/p\u003e \u003cp\u003eThis dose was chosen based on established respiratory safety data and preclinical efficacy reports.\u003c/p\u003e \u003cp\u003eAll treatments were administered once daily from postnatal day 0 to postnatal day 5.\u003c/p\u003e\n\u003ch3\u003eTissue Collection\u003c/h3\u003e\n\u003cp\u003eOn postnatal day 5, pups were euthanized with high-dose pentobarbital. Lungs were inflation-fixed with 10% neutral-buffered formalin, processed routinely, embedded in paraffin, and sectioned at a thickness of 5 \u0026micro;m for histopathological and immunohistochemical analyses.\u003c/p\u003e \u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003eHistopathological Evaluation\u003c/h2\u003e \u003cp\u003eHematoxylin and eosin (H\u0026amp;E) staining was performed on lung sections. A blinded pathologist evaluated:\u003c/p\u003e \u003cp\u003e \u003cul\u003e \u003cli\u003e \u003cp\u003eAlveolar structural maturation\u003c/p\u003e \u003c/li\u003e \u003cli\u003e \u003cp\u003eInterstitial thickness\u003c/p\u003e \u003c/li\u003e \u003cli\u003e \u003cp\u003eDegree of mononuclear inflammatory infiltration\u003c/p\u003e \u003c/li\u003e \u003cli\u003e \u003cp\u003eOverall architectural integrity\u003c/p\u003e \u003c/li\u003e \u003c/ul\u003e \u003c/p\u003e \u003cp\u003eA semi-quantitative scoring scale (0\u0026thinsp;=\u0026thinsp;none, 1\u0026thinsp;=\u0026thinsp;mild, 2\u0026thinsp;=\u0026thinsp;moderate, 3\u0026thinsp;=\u0026thinsp;severe) was applied. Representative micrographs are shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec12\" class=\"Section2\"\u003e \u003ch2\u003eImmunohistochemistry\u003c/h2\u003e \u003cp\u003eImmunohistochemical staining was conducted using antibodies against:\u003c/p\u003e \u003cp\u003e \u003cul\u003e \u003cli\u003e \u003cp\u003e \u003cb\u003eCaspase-3\u003c/b\u003e (apoptosis)\u003c/p\u003e \u003c/li\u003e \u003cli\u003e \u003cp\u003e \u003cb\u003ePCNA\u003c/b\u003e (proliferation)\u003c/p\u003e \u003c/li\u003e \u003cli\u003e \u003cp\u003e \u003cb\u003eABCA3\u003c/b\u003e (surfactant phospholipid transporter)\u003c/p\u003e \u003c/li\u003e \u003cli\u003e \u003cp\u003e \u003cb\u003eSFTPA1\u003c/b\u003e (surfactant protein A1)\u003c/p\u003e \u003c/li\u003e \u003cli\u003e \u003cp\u003e \u003cb\u003eAQP5\u003c/b\u003e (type I pneumocyte marker)\u003c/p\u003e \u003c/li\u003e \u003cli\u003e \u003cp\u003e \u003cb\u003eSP-B\u003c/b\u003e (surfactant protein B)\u003c/p\u003e \u003c/li\u003e \u003c/ul\u003e \u003c/p\u003e \u003cp\u003eThe primary antibodies used for immunohistochemistry, including manufacturer and catalog number, are summarized in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eAntibodies Used in Immunohistochemistry\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"3\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMarker\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eManufacturer\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eCatalog No.\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCaspase-3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eThermoFisher\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003ePA5-114687\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePCNA\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAbcam\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eab29\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eABCA3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAffbiotech\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eDF9245\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSFTPA1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAffbiotech\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eDF7204\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAQP5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAffbiotech\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eAF5169\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSP-B\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAffbiotech\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eDF8615\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eFollowing deparaffinization and antigen retrieval (citrate buffer, pH 6.0), sections were incubated with primary antibodies overnight at 4\u0026deg;C. Detection was performed using Horseradish peroxidase -conjugated secondary antibodies and 3,3\u0026rsquo;-diaminobenzidine.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec13\" class=\"Section2\"\u003e \u003ch2\u003eCompartment-Specific Analysis\u003c/h2\u003e \u003cp\u003eStaining intensity was evaluated separately in:\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec14\" class=\"Section2\"\u003e \u003ch2\u003e\u0026bull; Interstitial compartment\u003c/h2\u003e \u003cdiv id=\"Sec15\" class=\"Section3\"\u003e \u003ch2\u003e\u0026bull; Bronchiolar epithelial compartment\u003c/h2\u003e \u003cp\u003eQuantitative analysis was performed using QuPath v0.6.0, and results were expressed as the percentage of positively stained cells.\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv id=\"Sec16\" class=\"Section2\"\u003e \u003ch2\u003eStatistical Analysis\u003c/h2\u003e \u003cp\u003eData were analyzed using IBM SPSS Statistics for Windows, Version 20.0 (IBM Corp., Armonk, NY, USA) and GraphPad Prism 8 (GraphPad Software, Boston, MA, USA).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec17\" class=\"Section2\"\u003e \u003ch2\u003e\u0026bull; Histopathological scores:\u003c/h2\u003e \u003cp\u003e \u003cul\u003e \u003cli\u003e \u003cp\u003eKruskal\u0026ndash;Wallis test, followed by Bonferroni-adjusted Mann\u0026ndash;Whitney U pairwise comparisons.\u003c/p\u003e \u003c/li\u003e \u003c/ul\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec18\" class=\"Section2\"\u003e \u003ch2\u003e\u0026bull; Immunohistochemistry (% positive cells):\u003c/h2\u003e \u003cp\u003e \u003cul\u003e \u003cli\u003e \u003cp\u003eOne-Way ANOVA with Tukey\u0026rsquo;s post hoc test, after confirming normality (Shapiro\u0026ndash;Wilk test) and homogeneity of variance (Levene\u0026rsquo;s test).\u003c/p\u003e \u003c/li\u003e \u003c/ul\u003e \u003c/p\u003e \u003cp\u003eA two-sided p\u0026thinsp;\u0026lt;\u0026thinsp;0.05 was considered statistically significant.\u003c/p\u003e \u003c/div\u003e"},{"header":"Results","content":"\u003cdiv id=\"Sec20\" class=\"Section2\"\u003e \u003ch2\u003eHistopathological and Immunohistochemical Findings\u003c/h2\u003e \u003cp\u003eHistopathological evaluation showed that the Control, DEX, and BET groups maintained near-normal alveolar architecture with thin septa and no significant inflammatory infiltration. The ERDO group displayed mild interstitial infiltration but retained overall lung structure, suggesting a limited inflammatory response (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eImmunohistochemical analysis revealed distinct expression patterns across groups. Overall statistical comparisons showed significant differences for Caspase-3, PCNA, ABCA3, and SFTPA1 (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05), while AQP5 and SP-B were negative in all groups (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eCaspase-3 and PCNA were minimally expressed in the Control and ERDO groups but were significantly higher in the DEX and BET groups, indicating increased apoptosis and proliferation due to glucocorticoid exposure (Figs.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e and \u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eABCA3 was most strongly expressed in the ERDO group, followed by DEX, with lower levels in BET and Control (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eSFTPA1 was more prominent in the interstitial compartment of the ERDO group, while DEX and Control had higher epithelial expression (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eAQP5 and SP-B were not detected in any group, consistent with the expected low levels at this developmental stage (Figs.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003e and \u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e"},{"header":"Discussion","content":"\u003cp\u003ePreterm birth\u0026ndash;related respiratory distress syndrome remains a major cause of neonatal morbidity and mortality and is primarily driven by surfactant deficiency and structural immaturity of the lung. Antenatal corticosteroids are still the standard of care to accelerate fetal lung maturation and reduce early respiratory complications. However, concerns about possible long-term cardiometabolic or neurodevelopmental effects, especially with repeated or high-dose exposure, have renewed interest in alternative or adjunctive strategies that might support lung maturation with a more favourable safety profile [\u003cspan additionalcitationids=\"CR17 CR18 CR19\" citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eIn this preterm rat model, dexamethasone and betamethasone produced a nearly normal histological appearance, whereas erdosteine resulted in preserved alveolar structure with only mild interstitial mononuclear cell infiltration. This indicates that erdosteine does not exert harmful tissue effects but induces a modest inflammatory response. The minimal inflammation in the corticosteroid groups aligns with studies showing that antenatal betamethasone reduces inflammatory cell accumulation and stabilises alveolar structure [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e, \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]. Given that glucocorticoids suppress NF-κB\u0026ndash;dependent cytokine release and leukocyte recruitment [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e], the reduced inflammatory scores in DEX and BET are not unexpected. By contrast, the mild infiltration with erdosteine may reflect a more balanced immunomodulatory profile in which oxidative stress is attenuated without complete suppression of local defence mechanisms [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e, \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e, \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eCaspase-3 expression was increased in both the interstitial and bronchiolar epithelium of the corticosteroid-treated groups, consistent with previous ovine and rodent studies reporting steroid-induced epithelial apoptosis and thinning of alveolar septa [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e, \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e]. In contrast, caspase-3 positivity remained low in the erdosteine group, paralleling evidence that erdosteine and its active metabolite limit reactive oxygen species and mitigate mitochondrial stress\u0026ndash;related apoptotic pathways [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e, \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e, \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e]. These findings suggest that erdosteine may confer protection against excessive apoptosis during early lung development, in contrast to the more pronounced remodelling triggered by classical glucocorticoids.\u003c/p\u003e \u003cp\u003eThe PCNA expression pattern further supports this divergence. Dexamethasone showed the highest proliferative activity, followed by betamethasone, whereas erdosteine and control lungs exhibited lower levels. This is compatible with reports that glucocorticoids transiently enhance epithelial proliferation and differentiation before promoting maturation of alveolar structures [\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e, \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e]. The relatively modest PCNA positivity in the erdosteine group implies that it does not directly stimulate proliferation but may facilitate maturation through preservation of cellular integrity and redox balance\u0026mdash;an effect that could support surfactant pathways without provoking excessive architectural remodelling.\u003c/p\u003e \u003cp\u003eOne of the most striking findings is the ABCA3 expression profile. ABCA3, a key ATP-binding cassette lipid transporter in type II pneumocytes, is essential for phospholipid import, lamellar body maturation and surfactant homeostasis. Experimental and clinical studies demonstrate that ABCA3 dysfunction impairs lamellar body biogenesis, alters surfactant lipid composition and compromises alveolar stability [\u003cspan additionalcitationids=\"CR30 CR31\" citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e]. Loss-of-function ABCA3 variants are associated with lethal neonatal respiratory distress and interstitial lung disease, highlighting its central role in lung development [\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e, \u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e, \u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e]. Although corticosteroids are known to increase ABCA3 expression and lamellar body maturation in experimental settings [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e], our data showed the highest ABCA3 staining in the erdosteine group across both interstitial and bronchiolar regions. This suggests that erdosteine may amplify surfactant-related lipid transport not only through pathways overlapping with glucocorticoid responsiveness but also via redox-sensitive mechanisms that preserve phospholipid-synthesising enzymes and membrane transporter activity. The parallel increase in interstitial and epithelial compartments supports a global enhancement of surfactant trafficking.\u003c/p\u003e \u003cp\u003eSFTPA1 displayed a compartment-specific profile. Interstitial staining was most pronounced in the erdosteine group, while epithelial expression was higher in the control and DEX groups and lower in BET and ERDO. SFTPA1 is a major hydrophilic surfactant protein involved in surfactant structure, surface-tension regulation, pathogen opsonisation and immunomodulation [\u003cspan additionalcitationids=\"CR37\" citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e]. Its expression increases during the late canalicular and saccular stages, and contemporary explant, organoid and epithelial models confirm glucocorticoid-driven upregulation of SP-A [\u003cspan additionalcitationids=\"CR40 CR41\" citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e42\u003c/span\u003e]. The distribution observed here suggests that erdosteine may preferentially enhance interstitial or stromal surfactant-related immunoregulation, whereas corticosteroids more strongly influence epithelial differentiation and secretion patterns.\u003c/p\u003e \u003cp\u003eAQP5 and SP-B were immunonegative across all groups at postnatal day 5. This is consistent with developmental reports demonstrating that both markers increase closer to term and early postnatally, often remaining low at very early time points, particularly in immature lung models [\u003cspan additionalcitationids=\"CR44\" citationid=\"CR43\" class=\"CitationRef\"\u003e43\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e45\u003c/span\u003e]. Thus, their absence likely reflects developmental stage rather than intervention-specific suppression.\u003c/p\u003e \u003cp\u003eTaken together, these findings indicate that erdosteine supports preterm lung maturation in a manner partially overlapping with but distinct from classical corticosteroids. Erdosteine increased ABCA3 and interstitial SFTPA1 expression while maintaining low apoptosis and modest proliferation, accompanied by preserved lung architecture. Dexamethasone and betamethasone induced stronger apoptotic and proliferative responses, leading to near-normal histology but relatively lower ABCA3 levels than erdosteine. These patterns raise the hypothesis that thiol-based antioxidant therapy may complement or, in selected circumstances, partially substitute glucocorticoids in supporting surfactant biogenesis while potentially reducing systemic programming effects. Nevertheless, such strategies require rigorous evaluation of timing, dose and interaction with standard ACS regimens, ideally in clinically relevant models and, ultimately, in human trials.\u003c/p\u003e \u003cp\u003eThis study has several limitations. First, the sample size was modest and analyses were conducted at a single early postnatal time point, precluding assessment of longer-term structural or functional outcomes. Second, the immunohistochemical approach was semi-quantitative and targeted selected markers; molecular analyses and functional evaluations (lung mechanics, gas exchange) were not performed. Third, only one dosing regimen of each intervention was tested, and dose\u0026ndash;response or combination protocols were not explored. Finally, systemic effects on other organs\u0026mdash;which are pertinent to the broader safety considerations of ACS and antioxidant therapies\u0026mdash;were beyond the study\u0026rsquo;s scope.\u003c/p\u003e \u003cp\u003eDespite these limitations, this study provides initial experimental evidence that erdosteine can modulate key surfactant-regulatory markers such as ABCA3 and SFTPA1 in the preterm lung, with an apoptosis\u0026ndash;proliferation profile distinct from dexamethasone and betamethasone. These results support further investigation of erdosteine as a potential adjunct or alternative to antenatal corticosteroids, particularly in models integrating functional respiratory outcomes and long-term follow-up.\u003c/p\u003e"},{"header":"Conclusions","content":"\u003cp\u003eIn this preterm rat model, erdosteine exhibited a maturation profile that was clearly distinct from that of dexamethasone and betamethasone. While classical antenatal corticosteroids generated robust apoptotic and proliferative activity consistent with accelerated structural maturation, erdosteine produced minimal apoptosis, preserved alveolar architecture and a comparatively modest proliferative response. Most notably, erdosteine markedly increased ABCA3 expression and enhanced interstitial SFTPA1 staining, suggesting a favourable impact on surfactant-related lipid transport and innate immune readiness. These effects emerged without the degree of tissue remodelling observed in the corticosteroid groups.\u003c/p\u003e \u003cp\u003eTaken together, the data indicate that thiol-based antioxidant therapy may support surfactant biogenesis and early lung maturation through mechanisms partially overlapping with, yet biologically distinct from, glucocorticoid-driven pathways. Although the present findings are limited by sample size, a single postnatal time point and the absence of functional respiratory assessments, they provide preliminary experimental evidence that erdosteine could serve as an adjunctive or, under selected conditions, a partial alternative to antenatal corticosteroids. Future studies incorporating dose\u0026ndash;response analyses, combined regimens, long-term structural and functional outcomes, and translationally relevant models will be essential to define the therapeutic potential and safety profile of erdosteine in the context of preterm lung maturation.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cdiv class=\"DefinitionList\"\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eABCA3\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eATP-binding cassette subfamily A member 3\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eACS\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eAntenatal corticosteroids\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eAQP5\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eAquaporin-5\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eBET\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eBetamethasone\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eDEX\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eDexamethasone\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eERDO\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eErdosteine\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eH\u0026amp;E\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eHematoxylin and eosin\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eIHC\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eImmunohistochemistry\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003ePCNA\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eProliferating cell nuclear antigen\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eSFTPA1\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eSurfactant protein A1\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eSP-A\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eSurfactant protein A\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eSP-B\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eSurfactant protein B\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eSPSS\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eStatistical Package for the Social Sciences\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003c/div\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAuthor Contributions\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eS.O.G. conducted the conceptualization and study design, supervised the research, performed histopathological evaluations, interpreted the data, drafted the manuscript, and approved the final version. C.Y. contributed to the methodology, supervised the study, and critically revised the manuscript. M.S. performed the animal procedures, administered the treatments, developed the experimental model, and collected the data. A.S.K. carried out the laboratory processing, conducted the immunohistochemical analyses, and contributed to data acquisition. M.O. performed the histopathological examinations, scoring, validation, and visualization. All authors read and approved the final manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding Statement\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study was supported by the Sivas Cumhuriyet University Scientific Research Projects Commission (CUBAP) under project number T-2024-1043.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgment\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors thank the Sivas Cumhuriyet University Experimental Animal Research Center staff for their technical assistance during animal care and procedures.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthics Approval and Consent to Participate\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study was approved by the Sivas Cumhuriyet University Animal Experiments Local Ethics Committee (HADYEK) with the decision dated 24.11.2023 and numbered 658. All procedures were conducted in accordance with institutional guidelines and the ARRIVE recommendations.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting Interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare that they have no competing interests.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData Availability Statement\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe datasets generated and analyzed during the current study are available from the corresponding author on reasonable request.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent to Publish Declaration\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eChawanpaiboon, S. et al. Global, regional, and national estimates of levels of preterm birth in 2014: a systematic review and modelling analysis. \u003cem\u003eLancet Glob Health\u003c/em\u003e. \u003cb\u003e7\u003c/b\u003e (1), e37\u0026ndash;e46. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/S2214-109X(18)30451-0\u003c/span\u003e\u003cspan address=\"10.1016/S2214-109X(18)30451-0\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2019).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eCiapponi, A. et al. Dexamethasone versus betamethasone for preterm birth: a systematic review and network meta-analysis. \u003cem\u003eAm. J. Obstet. Gynecol. MFM\u003c/em\u003e. \u003cb\u003e3\u003c/b\u003e (3), 100312. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.ajogmf.2021.100312\u003c/span\u003e\u003cspan address=\"10.1016/j.ajogmf.2021.100312\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2021).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eStoll, B. J. et al. Trends in care practices, morbidity, and mortality of extremely preterm neonates, 1993\u0026ndash;2012. \u003cem\u003eJAMA\u003c/em\u003e \u003cb\u003e314\u003c/b\u003e (10), 1039\u0026ndash;1051. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1001/jama.2015.10244\u003c/span\u003e\u003cspan address=\"10.1001/jama.2015.10244\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2015).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRoberts, D., Brown, J., Medley, N. \u0026amp; Dalziel, S. R. Antenatal corticosteroids for accelerating fetal lung maturation for women at risk of preterm birth. \u003cem\u003eCochrane Database Syst. Rev.\u003c/em\u003e (3), CD004454. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1002/14651858.CD004454.pub3\u003c/span\u003e\u003cspan address=\"10.1002/14651858.CD004454.pub3\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2017).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMeyer, N., Kallapur, S. G., Ikegami, M. \u0026amp; Jobe, A. H. Antenatal corticosteroids and surfactant protein expression in preterm lung development. \u003cem\u003eFront. Physiol.\u003c/em\u003e \u003cb\u003e11\u003c/b\u003e, 565213. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.3389/fphys.2020.565213\u003c/span\u003e\u003cspan address=\"10.3389/fphys.2020.565213\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2020).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMatthews, S. G. Antenatal glucocorticoids and programming of the developing hypothalamo\u0026ndash;pituitary\u0026ndash;adrenal axis. \u003cem\u003ePediatr. Res.\u003c/em\u003e \u003cb\u003e47\u003c/b\u003e (1), 4\u0026ndash;13. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1203/00006450-200001000-00002\u003c/span\u003e\u003cspan address=\"10.1203/00006450-200001000-00002\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2000).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSeckl, J. R. \u0026amp; Meaney, M. J. Glucocorticoid programming. \u003cem\u003eAnn. N Y Acad. Sci.\u003c/em\u003e \u003cb\u003e1032\u003c/b\u003e, 63\u0026ndash;84. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1196/annals.1314.006\u003c/span\u003e\u003cspan address=\"10.1196/annals.1314.006\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2004).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMoisiadis, V. G. \u0026amp; Matthews, S. G. Glucocorticoids and fetal programming part 1: Outcomes. \u003cem\u003eNat. Rev. Endocrinol.\u003c/em\u003e \u003cb\u003e10\u003c/b\u003e (7), 391\u0026ndash;402. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1038/nrendo.2014.73\u003c/span\u003e\u003cspan address=\"10.1038/nrendo.2014.73\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2014).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eCarson, C. et al. Association between antenatal corticosteroids and risk of serious neonatal outcomes: population-based cohort study. \u003cem\u003eBMJ\u003c/em\u003e \u003cb\u003e382\u003c/b\u003e, e075835. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1136/bmj-2023-075835\u003c/span\u003e\u003cspan address=\"10.1136/bmj-2023-075835\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2023).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLiu, M. et al. Prenatal dexamethasone exposure programs the development and function of the testis. \u003cem\u003eReprod. Fertil. Dev.\u003c/em\u003e \u003cb\u003e34\u003c/b\u003e (19), RFD20164. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1071/RD20164\u003c/span\u003e\u003cspan address=\"10.1071/RD20164\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2022).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLiu, Y. et al. Prenatal dexamethasone exposure impairs rat blood\u0026ndash;testis barrier and sperm quality. \u003cem\u003eActa Pharmacol. Sin\u003c/em\u003e. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1038/s41401-024-01244-5\u003c/span\u003e\u003cspan address=\"10.1038/s41401-024-01244-5\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2024).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRistić, N. et al. Prenatal dexamethasone and ovary development: a structural study in the rat. \u003cem\u003eToxicol. Appl. Pharmacol.\u003c/em\u003e \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.taap.2020.115345\u003c/span\u003e\u003cspan address=\"10.1016/j.taap.2020.115345\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2021).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eCazzola, M., Rogliani, P., Calzetta, L. \u0026amp; Matera, M. G. Multifaceted beneficial effects of erdosteine: more than a mucolytic agent. \u003cem\u003eDrugs\u003c/em\u003e \u003cb\u003e80\u003c/b\u003e (15), 1605\u0026ndash;1617. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1007/s40265-020-01412-x\u003c/span\u003e\u003cspan address=\"10.1007/s40265-020-01412-x\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2020).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDal Negro, R. W. \u0026amp; Visconti, M. Erdosteine reduces the exercise-induced oxidative stress in patients with severe COPD: results of a placebo-controlled trial. \u003cem\u003ePulm Pharmacol. Ther.\u003c/em\u003e \u003cb\u003e41\u003c/b\u003e, 48\u0026ndash;51. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.pupt.2016.09.007\u003c/span\u003e\u003cspan address=\"10.1016/j.pupt.2016.09.007\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2016).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePisi, R. \u0026amp; Chetta, A. Erdosteine in children and adults with bronchiectasis: efficacy, safety and future perspectives. \u003cem\u003eMultidiscip Respir Med.\u003c/em\u003e \u003cb\u003e19\u003c/b\u003e (1), 6. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1186/s40248-024-00221-7\u003c/span\u003e\u003cspan address=\"10.1186/s40248-024-00221-7\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2024).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKelly, B. A. et al. Antenatal corticosteroids and offspring cardiovascular health: a review. \u003cem\u003ePlacenta\u003c/em\u003e \u003cb\u003e97\u003c/b\u003e, 65\u0026ndash;72. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.placenta.2020.06.014\u003c/span\u003e\u003cspan address=\"10.1016/j.placenta.2020.06.014\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2020).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMurphy, K. E. et al. Multiple courses of antenatal corticosteroids for preterm birth: a systematic review and meta-analysis. \u003cem\u003eBJOG\u003c/em\u003e \u003cb\u003e128\u003c/b\u003e (8), 1357\u0026ndash;1367. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1111/1471-0528.16607\u003c/span\u003e\u003cspan address=\"10.1111/1471-0528.16607\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2021).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSultana, S. et al. Long-term outcomes of antenatal corticosteroids for preterm birth: a systematic review. \u003cem\u003ePLOS Glob Public. Health\u003c/em\u003e. \u003cb\u003e5\u003c/b\u003e (3), e0004575. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1371/journal.pgph.0004575\u003c/span\u003e\u003cspan address=\"10.1371/journal.pgph.0004575\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2025).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLiauw, J. et al. Antenatal corticosteroids and child neurodevelopment: a systematic review and meta-analysis. \u003cem\u003eObstet. Gynecol.\u003c/em\u003e \u003cb\u003e146\u003c/b\u003e (5), 360\u0026ndash;376. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1097/AOG.0000000000005950\u003c/span\u003e\u003cspan address=\"10.1097/AOG.0000000000005950\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2025).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eTosto, V. et al. Antenatal corticosteroids in early and late fetal growth restriction. \u003cem\u003eJ. Clin. Med.\u003c/em\u003e \u003cb\u003e14\u003c/b\u003e (14), 4876. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.3390/jcm14144876\u003c/span\u003e\u003cspan address=\"10.3390/jcm14144876\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2025).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eIkegami, M. et al. Betamethasone treatment of fetal sheep lung: effects on lung compliance, surfactant, and morphology. \u003cem\u003eAm. J. Physiol. Lung Cell. Mol. Physiol.\u003c/em\u003e \u003cb\u003e272\u003c/b\u003e (5), L915\u0026ndash;L924. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1152/ajplung.1997.272.5.L915\u003c/span\u003e\u003cspan address=\"10.1152/ajplung.1997.272.5.L915\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (1997).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eJobe, A. H. et al. Repeated antenatal corticosteroid treatments in preterm sheep: lung morphology and morphometry. \u003cem\u003ePediatr. Res.\u003c/em\u003e \u003cb\u003e43\u003c/b\u003e (1), 31\u0026ndash;37. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1203/00006450-199801000-00006\u003c/span\u003e\u003cspan address=\"10.1203/00006450-199801000-00006\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (1998).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRhen, T. \u0026amp; Cidlowski, J. A. Antiinflammatory action of glucocorticoids\u0026mdash;new mechanisms for old drugs. \u003cem\u003eN Engl. J. Med.\u003c/em\u003e \u003cb\u003e353\u003c/b\u003e (16), 1711\u0026ndash;1723. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1056/NEJMra050541\u003c/span\u003e\u003cspan address=\"10.1056/NEJMra050541\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2005).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSantus, P., Strizzi, S., Danzo, F., Biasin, M. \u0026amp; Trabattoni, D. Antiviral and immunomodulatory activity of erdosteine in human respiratory epithelial cells infected with respiratory viruses. \u003cem\u003ePathogens\u003c/em\u003e \u003cb\u003e14\u003c/b\u003e (4), 388. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.3390/pathogens14040388\u003c/span\u003e\u003cspan address=\"10.3390/pathogens14040388\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2025).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKallapur, S. G., Jobe, A. H. \u0026amp; Ikegami, M. Increased alveolar cell apoptosis and decreased epithelial proliferation after fetal exposure to corticosteroids in sheep. \u003cem\u003eAm. J. Physiol. Lung Cell. Mol. Physiol.\u003c/em\u003e \u003cb\u003e292\u003c/b\u003e (1), L92\u0026ndash;L101. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1152/ajplung.00286.2006\u003c/span\u003e\u003cspan address=\"10.1152/ajplung.00286.2006\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2007).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMoretti, M. \u0026amp; Marchioni, C. F. An overview of erdosteine antioxidant activity in experimental research. \u003cem\u003eCurr. Drug Targets\u003c/em\u003e. \u003cb\u003e8\u003c/b\u003e (1), 81\u0026ndash;88. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.phrs.2006.12.006\u003c/span\u003e\u003cspan address=\"10.1016/j.phrs.2006.12.006\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2007).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eO\u0026rsquo;Brodovich, H. M. et al. Glucocorticoid regulation of lung epithelial ion transport and development. \u003cem\u003eAm. J. Physiol. Lung Cell. Mol. Physiol.\u003c/em\u003e \u003cb\u003e284\u003c/b\u003e (4), L595\u0026ndash;L604. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1152/ajplung.00328.2002\u003c/span\u003e\u003cspan address=\"10.1152/ajplung.00328.2002\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2003).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWang, Y. et al. Glucocorticoid regulation of cell proliferation and differentiation in developing lung. \u003cem\u003eJ. Endocrinol.\u003c/em\u003e \u003cb\u003e181\u003c/b\u003e (1), 33\u0026ndash;44. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1677/joe.0.1810033\u003c/span\u003e\u003cspan address=\"10.1677/joe.0.1810033\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2004).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWhitsett, J. A. \u0026amp; Weaver, T. E. Alveolar development and disease. \u003cem\u003eAnnu. Rev. Physiol.\u003c/em\u003e \u003cb\u003e77\u003c/b\u003e, 493\u0026ndash;515. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1146/annurev-physiol-021014-071842\u003c/span\u003e\u003cspan address=\"10.1146/annurev-physiol-021014-071842\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2015).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBan, N. et al. ABCA3 as a lipid transporter in lung lamellar bodies. \u003cem\u003eJ. Biol. Chem.\u003c/em\u003e \u003cb\u003e282\u003c/b\u003e (7), 4321\u0026ndash;4329. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1074/jbc.M611767200\u003c/span\u003e\u003cspan address=\"10.1074/jbc.M611767200\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2007).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eShulenin, S. et al. ABCA3 gene mutations in newborns with fatal surfactant deficiency. \u003cem\u003eN Engl. J. Med.\u003c/em\u003e \u003cb\u003e350\u003c/b\u003e (13), 1296\u0026ndash;1303. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1056/NEJMoa032178\u003c/span\u003e\u003cspan address=\"10.1056/NEJMoa032178\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2004).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWambach, J. A. et al. Genotype\u0026ndash;phenotype correlations for ABCA3 mutations in infants and children with diffuse lung disease. \u003cem\u003eAm. J. Respir Crit. Care Med.\u003c/em\u003e \u003cb\u003e189\u003c/b\u003e (12), 1538\u0026ndash;1543. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1164/rccm.201402-0342OC\u003c/span\u003e\u003cspan address=\"10.1164/rccm.201402-0342OC\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2014).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eNolan, J., Rodgers, J. \u0026amp; Mackintosh, J. A. ABCA3 Surfactant-Related Gene Variant Associated Interstitial Lung Disease in Adults: A Case Series and Review of the Literature. \u003cem\u003eRespirol. Case Rep.\u003c/em\u003e \u003cb\u003e13\u003c/b\u003e (8), e70304. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1002/rcr2.70304\u003c/span\u003e\u003cspan address=\"10.1002/rcr2.70304\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2025).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eNogee, L. M., deMello, D. E., Dehner, L. P. \u0026amp; Colten, H. R. Deficiency of pulmonary surfactant protein A in congenital alveolar proteinosis. \u003cem\u003eJ. Clin. Invest.\u003c/em\u003e \u003cb\u003e91\u003c/b\u003e (2), 842\u0026ndash;847. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1172/JCI116267\u003c/span\u003e\u003cspan address=\"10.1172/JCI116267\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (1993).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eYoshida, I. et al. Expression of ABCA3, a causative gene for fatal surfactant deficiency, is up-regulated by glucocorticoids in lung alveolar type II cells. \u003cem\u003eBiochem. Biophys. Res. Commun.\u003c/em\u003e \u003cb\u003e323\u003c/b\u003e (2), 547\u0026ndash;555. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.bbrc.2004.08.133\u003c/span\u003e\u003cspan address=\"10.1016/j.bbrc.2004.08.133\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2004).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eThorenoor, N., Umstead, T. M., Zhang, X., Phelps, D. S. \u0026amp; Floros, J. Survival of Surfactant Protein-A1 and SP-A2 transgenic mice after Klebsiella pneumoniae infection exhibits sex-, gene- and variant-specific differences. \u003cem\u003eFront. Immunol.\u003c/em\u003e \u003cb\u003e9\u003c/b\u003e, 2404. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.3389/fimmu.2018.02404\u003c/span\u003e\u003cspan address=\"10.3389/fimmu.2018.02404\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2018).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eFloros, J. et al. Human surfactant protein SP-A1 and SP-A2 variants differentially affect the alveolar microenvironment and innate immune responses. \u003cem\u003eFront. Immunol.\u003c/em\u003e \u003cb\u003e12\u003c/b\u003e, 681639. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.3389/fimmu.2021.681639\u003c/span\u003e\u003cspan address=\"10.3389/fimmu.2021.681639\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2021).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDepicolzuane, L., Phelps, D. S. \u0026amp; Floros, J. Surfactant protein A function: knowledge gained from SP-A knockout mice. \u003cem\u003eFront. Pediatr.\u003c/em\u003e \u003cb\u003e9\u003c/b\u003e, 799693DOI. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.3389/fped.2021.799693\u003c/span\u003e\u003cspan address=\"10.3389/fped.2021.799693\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2022).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eJin, N. et al. Dexamethasone enhances surfactant protein expression in alveolar epithelial cells via MAPK and glucocorticoid receptor pathways. \u003cem\u003eAm. J. Physiol. Lung Cell. Mol. Physiol.\u003c/em\u003e \u003cb\u003e314\u003c/b\u003e (4), L615\u0026ndash;L624. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1152/ajplung.00310.2017\u003c/span\u003e\u003cspan address=\"10.1152/ajplung.00310.2017\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2018).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLin, S. et al. Dexamethasone promotes maturation of human fetal lung explants with increased SP-A and SP-B expression. \u003cem\u003eJ. Matern Fetal Neonatal Med.\u003c/em\u003e \u003cb\u003e30\u003c/b\u003e (3), 322\u0026ndash;329. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.3109/14767058.2016.1169528\u003c/span\u003e\u003cspan address=\"10.3109/14767058.2016.1169528\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2017).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSanchez-Esteban, J. et al. Mechanical stretch and glucocorticoids synergistically upregulate surfactant protein A in developing lung cells. \u003cem\u003ePediatr. Res.\u003c/em\u003e \u003cb\u003e85\u003c/b\u003e (3), 361\u0026ndash;368. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1038/s41390-018-0259-5\u003c/span\u003e\u003cspan address=\"10.1038/s41390-018-0259-5\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2019).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAlysandratos, K. D. et al. Glucocorticoid exposure promotes alveolar epithelial maturation and increases expression of surfactant proteins in human lung organoids. \u003cem\u003eStem Cell. Rep.\u003c/em\u003e \u003cb\u003e16\u003c/b\u003e (12), 3000\u0026ndash;3015. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.stemcr.2021.10.009\u003c/span\u003e\u003cspan address=\"10.1016/j.stemcr.2021.10.009\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2021).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRam\u0026iacute;rez, R. J. et al. Transepithelial sodium transport and lung fluid balance are regulated by alveolar type I cell differentiation. \u003cem\u003eAm. J. Physiol. Lung Cell. Mol. Physiol.\u003c/em\u003e \u003cb\u003e278\u003c/b\u003e (4), L659\u0026ndash;L666. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1152/ajplung.2000.278.4.L659\u003c/span\u003e\u003cspan address=\"10.1152/ajplung.2000.278.4.L659\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2000).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eXu, J. et al. Developmental regulation of aquaporin-5 expression in perinatal mouse lung. \u003cem\u003ePediatr. Res.\u003c/em\u003e \u003cb\u003e66\u003c/b\u003e (4), 371\u0026ndash;377. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1203/PDR.0b013e3181b45592\u003c/span\u003e\u003cspan address=\"10.1203/PDR.0b013e3181b45592\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2009).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eYadav, A. et al. Hyperoxia disrupts aquaporin-5 expression and alveolar epithelial maturation in the neonatal lung. \u003cem\u003eAm. J. Physiol. Lung Cell. Mol. Physiol.\u003c/em\u003e \u003cb\u003e318\u003c/b\u003e (4), L645\u0026ndash;L658. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1152/ajplung.00530.2019\u003c/span\u003e\u003cspan address=\"10.1152/ajplung.00530.2019\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2020).\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"scientific-reports","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"scirep","sideBox":"Learn more about [Scientific Reports](http://www.nature.com/srep/)","snPcode":"","submissionUrl":"","title":"Scientific Reports","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Scientific Reports","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Preterm birth, antenatal corticosteroid, erdosteine, lung maturation, surfactant proteins","lastPublishedDoi":"10.21203/rs.3.rs-8395257/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8395257/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003eBackground: \u003c/strong\u003ePreterm birth remains a major contributor to neonatal morbidity, largely due to immature lung structure and insufficient surfactant production. This study evaluated the potential of erdosteine as an alternative or complementary agent to antenatal corticosteroids (ACS) by comparing its effects on lung maturation with dexamethasone (DEX) and betamethasone (BET) in a preterm rat model. Particular emphasis was placed on two anatomical compartments: the interstitial area and the bronchiolar epithelium.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMethods: \u003c/strong\u003ePreterm delivery was induced by cesarean section on gestational day 16 in Sprague–Dawley rats. Newborn pups were assigned to four groups: control, DEX, BET, and erdosteine (ERDO). Lung tissues collected on postnatal day 5 underwent histopathological evaluation and immunohistochemical analysis of Caspase-3, PCNA, ABCA3, SFTPA1, AQP5, and SP-B. Staining intensity was semi-quantitatively scored in both compartments.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eResults: \u003c/strong\u003eDEX and BET produced lung histology that closely resembled normal tissue architecture, whereas ERDO resulted in only mild interstitial mononuclear infiltration. Caspase-3 and PCNA expression markedly increased in both compartments of the DEX and BET groups but remained low in ERDO and controls. ABCA3 expression was most pronounced in the ERDO group across both compartments (p \u0026lt; 0.001), surpassing even the corticosteroid groups. SFTPA1 was highest in the interstitial area of ERDO-treated pups, while bronchiolar epithelial staining was more evident in the control and DEX groups. AQP5 and SP-B did not show significant positivity in any group.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConclusions:\u003c/strong\u003e Erdosteine demonstrated a supportive and biologically meaningful pattern of lung maturation, with reduced inflammation and balanced cellular turnover, accompanied by a notable increase in surfactant-related markers—particularly ABCA3. While not replicating all effects of antenatal corticosteroids, its favorable molecular profile and absence of corticosteroid-associated tissue alterations highlight its potential as a gentler, complementary approach to promoting pulmonary readiness in preterm neonates. These findings warrant further investigation in broader experimental and clinical settings.\u003c/p\u003e","manuscriptTitle":"Erdosteine as a Novel Modulator of Surfactant Maturation: A Comparative Analysis With Dexamethasone and Betamethasone in a Preterm Rat Lung Model","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-01-27 00:07:13","doi":"10.21203/rs.3.rs-8395257/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2026-02-20T05:48:55+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-02-06T02:06:28+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-01-29T09:39:03+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"41731399619902059357307583627361985154","date":"2026-01-26T19:08:42+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"66311914432025754176057726006259357192","date":"2026-01-24T11:13:39+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-01-22T00:45:18+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-01-15T08:45:16+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2025-12-24T21:11:52+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-12-22T17:19:20+00:00","index":"","fulltext":""},{"type":"submitted","content":"Scientific Reports","date":"2025-12-22T17:13:35+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"scientific-reports","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"scirep","sideBox":"Learn more about [Scientific Reports](http://www.nature.com/srep/)","snPcode":"","submissionUrl":"","title":"Scientific Reports","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Scientific Reports","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"88f353e2-99a1-4490-8274-4b4235948f52","owner":[],"postedDate":"January 27th, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[{"id":61605259,"name":"Health sciences/Diseases"},{"id":61605260,"name":"Health sciences/Medical research"},{"id":61605261,"name":"Biological sciences/Physiology"}],"tags":[],"updatedAt":"2026-05-18T10:54:38+00:00","versionOfRecord":[],"versionCreatedAt":"2026-01-27 00:07:13","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8395257","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8395257","identity":"rs-8395257","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}