Pyroptosis in endometritis: Molecular mechanisms, pathogenic roles, and therapeutic opportunities

The development of endometritis is a multi-factorial pathological process initiated by microbial invasion, sustained by dysregulated immune responses, and exacerbated by progressive tissue injury. 29 Recent studies indicate that pyroptosis serves as a central mechanistic bridge in this continuum; it contributes to pathogen clearance while simultaneously driving persistent inflammation, epithelial barrier disruption, and disease chronicity. 70 This section examines the role of pyroptosis in endometritis across four interconnected dimensions: pathogen infection, inflammasome activation, immune cell responses, and maintenance of chronic inflammation. Pathogen invasion represents the primary trigger for endometritis and involves common reproductive tract pathogens such as E. coli , Mycoplasma , Chlamydia trachomatis , and various anaerobic bacteria. 71 PAMPs serve as essential signals for initiating host immune responses, among which LPS is one of the most potent stimuli. 72 In vitro and animal studies have demonstrated that LPS activates the TLR4-NF-κB signaling axis, inducing the transcription of inflammasome-related genes—including NLRP3 , pro-IL-1β , and pro-IL-18 —a process referred to as “priming” that establishes the prerequisite framework for subsequent pyroptotic activation. 73 , 74 , 75 Importantly, LPS not only acts as an indirect activator of inflammasome priming but can also directly enter the cytosol and bind caspase-4/5 in humans or caspase-11 in mice, thereby activating the noncanonical pyroptosis pathway. 76 This pathway bypasses traditional PRRs and induces GSDMD cleavage, pore formation, and proinflammatory mediator release. 77 In the context of the endometrium, this mechanism implies that once pathogens breach the mucosal barrier or gain cytosolic entry through endocytosis, they can rapidly induce pyroptotic cell death and trigger a potent inflammatory cascade. 78 Clinically, acute endometritis frequently arises following childbirth, miscarriage, or intrauterine procedures, during which the uterine barrier is transiently compromised and becomes highly susceptible to microbial invasion and colonization. 79 , 80 As an early-acting host defense mechanism, pyroptosis can induce the rapid release of IL-1β, IL-18, and DAMPs within hours, thereby facilitating the recruitment of neutrophils and macrophages into the endometrial tissues. 81 Although such acute inflammatory responses are essential for pathogen control, excessive or prolonged pyroptosis may exacerbate tissue injury and contribute to pathological changes associated with progression toward chronic endometritis (CE). Inflammasomes are central molecular platforms that mediate pyroptosis, and among these, the NLRP3 inflammasome is the most extensively studied and most strongly associated with infection-related inflammatory responses. 82 Canonical NLRP3 activation generally requires two signals: the first involves pathogen-derived or inflammatory stimuli that activate NF-κB and upregulate NLRP3, pro-IL-1β, and pro-IL-18; the second is provided by intracellular danger signals such as ATP, ROS, K + efflux, high-mobility group box 1 (HMGB1), and other DAMPs. 83 However, emerging evidence indicates that inflammasome activation is not merely a linear “two-signal” process but involves spatially organized and dynamically regulated molecular events. 84 For example, ASC liquid-liquid phase separation (LLPS) has been identified as a critical step in inflammasome assembly, with its phase behavior influenced by intracellular ionic conditions, mitochondrial fitness, metabolic status, and hormonal cues, including estrogen signaling. 85 , 86 These findings raise the question of whether cyclical hormonal changes, local hypoxia, or alterations in iron metabolism within the endometrial microenvironment modulate inflammasome activation thresholds—an area that warrants further investigation. In endometrial epithelial cells, pathogen invasion and tissue injury markedly increase ROS production and HMGB1 release. These DAMPs act as potent “second signals” that rapidly activate the NLRP3 inflammasome, leading to caspase-1 activation and GSDMD cleavage, ultimately inducing pyroptosis. 87 Pyroptotic cell death compromises epithelial barrier integrity and is accompanied by substantial release of IL-1β and IL-18, which further intensify the local and systemic inflammatory responses. 88 This mechanism may help explain why a subset of patients continue to exhibit persistent inflammation even after the pathogen burden diminishes or is eradicated 89 ; however, further evidence is required to validate this hypothesis. Endometrial stromal cells also express NLRP3 and additional inflammasome components. 85 Pyroptosis in these stromal cells disrupts tissue architecture and disturbs fibroblast-immune cell homeostasis. 90 Recent studies have suggested that chronic endometritis, which is often associated with RIF, is characterized by fibrosis and impaired stromal-cell function—changes that may be linked to excessive inflammasome activation in stromal cells. Nonetheless, most existing studies remain correlational, and more direct functional evidence is required to substantiate this relationship. 91 Collectively, aberrant inflammasome activation appears to be not only a key component of the innate immune response but also a potential driver of endometrial barrier disruption, progressive tissue injury, and reproductive impairment. Current basic and preclinical evidence suggests that innate immune cells residing in, or recruited to, the endometrium—including macrophages, dendritic cells, and neutrophils—can undergo pyroptosis or other inflammatory forms of cell death during endometritis and related uterine infections, thereby contributing to the amplification of local inflammation. 92 However, the specific contribution and predominant signaling pathways of each immune cell subset remain largely inferred from in vitro and animal models, rather than studies of human endometrial tissue. Macrophages can undergo pyroptosis via the caspase-1 or caspase-4/5 pathway in response to LPS, HMGB1, or oxidative stress. 93 Their susceptibility to pyroptosis is shaped by M1/M2 polarization states and metabolic reprogramming; for example, enhanced glycolysis has been linked to increased NLRP3 activation. 94 Reduced immune tolerance and a shift toward Th1-dominant immunity, as reported in several studies of endometritis, suggest a potential role for macrophage pyroptosis as an inflammatory “amplifier” 95 ; however, existing evidence remains largely indirect, and causal relationships within human endometrial tissue have yet to be delineated. In neutrophils, GSDMD cleavage and pyroptosis-like features have been observed under certain stimuli, with pore-induced ionic fluxes proposed to facilitate neutrophil extracellular trap (NET) release and contribute to tissue injury. 96 Overall, while immune cell pyroptosis has clear biological potential to intensify inflammatory signaling, its cell type specificity, relative pathway contributions, and interactions with other immune programs—such as antigen presentation and the maintenance of mucosal immune tolerance—require systematic investigation in human studies. Chronic endometritis is characterized by persistent low-grade inflammation, plasma cell infiltration, and impaired tissue repair—pathological changes that cannot be fully explained by pathogen burden or acute infection alone. 97 Emerging research suggests that pyroptosis-related pathways may provide a conceptual framework for understanding how inflammation persists after microbial clearance 97 ; however, the current evidence again stems predominantly from in vitro and animal studies. The abundant release of IL-1β and IL-18 during pyroptosis can drive a local Th1 shift and enhance IFN-γ production, thereby disrupting the endometrium’s normally tolerogenic immune milieu and maintaining a sustained proinflammatory state. 98 Conversely, pyroptosis-associated DAMPs, such as HMGB1, can repeatedly activate PRRs and downstream inflammasomes, establishing a “DAMP-inflammasome-DAMP” positive feedback loop that may perpetuate inflammatory signaling, even in the absence of continued pathogen input. 99 Moreover, accumulating evidence indicates that epigenetic regulation plays an important role in modulating the sensitivity of the inflammasome and pyroptotic pathways. 100 MicroRNAs (miRNAs) such as miR-495-3p and miR-223, long noncoding RNAs including NEAT1, and alterations in DNA methylation have been shown in various models to regulate the expression and stability of NLRP3 or GSDMD, thereby shifting the “activation threshold” of endometrial cells in response to inflammatory stimuli. 101 Conceptually, these mechanisms may help explain clinical observations in patients with chronic endometritis, such as recurrent inflammation and the persistence of a proinflammatory microenvironment despite standard antibiotic therapy.

Although the molecular mechanisms of pyroptosis are well characterized in experimental systems, their precise contribution to the pathophysiology of human endometritis requires validation across multiple levels of evidence. This section synthesizes current findings according to evidence level and provides a critical evaluation of their strengths and limitations, as summarized in Table 1 . Overall, current evidence supporting a role for pyroptosis in endometritis is derived predominantly from in vitro studies and animal models, whereas human investigations remain limited and are largely correlational. Accordingly, the causal contribution and translational relevance of pyroptosis in clinical disease should be interpreted with caution and warrant further rigorous evaluation. Table 1 Representative preclinical and clinical studies on pyroptosis in endometritis Evidence level Model Induction Menstrual cycle phase at sampling Markers measured Endometrial manifestations Main findings Methods Reference In vitro (cell-based) bovine endometrial epithelial cells LPS N/A (animal study) NLRP3↑, caspase-1 activation↑, caspase-4↑, GSDMD cleavage↑, IL-1β↑, IL-18↑ membrane pore formation, elevated LDH release, and pyroptotic morphology LPS induces BEEC pyroptosis through NLRP3-caspase-1-GSDMD and caspase-4-GSDMD pathways, leading to IL-1β/IL-18 release and enhanced inflammation ELISA, LDH release assay Ma et al. 92 In vitro (cell-based bovine endometrial epithelial cells NETs or LPS N/A (animal study) NLRP3↑, ASC↑, caspase-1↑, caspase-4↑, GSDMD-N↑, IL-1β↑, IL-18↑, TNF-α↑ endometrial structural damage, infiltration of inflammatory cells (such as neutrophils); at the cellular level, features of pyroptosis were observed NETs can activate the NLRP3 inflammasome and promote GSDMD cleavage, enhancing the release of IL-1β and IL-18, thereby driving endometrial inflammatory injury.。 western blot, ELISA Shen et al. 96 In vitro (cell-based chronic endometritis in patients with infertility macrophage-induced pyroptosis proliferative phase (day 9–11 of menstrual cycle; hysteroscopy/biopsy) HMGB1,GSDMD-NT, CD68, and inflammatory markers increased number of CD138 + plasma cells and infiltration of inflammatory cells were observed HMGB1 was elevated in chronic endometritis patients’ endometrium and uterine fluid, linked to plasma cell infiltration; promoted macrophage pyroptosis; and glycyrrhizic acid reduced associated inflammation. western blot Yang et al. 102 In vitro (cell-based bovine endometrial epithelial cells LPS N/A (animal study) NLRP3↑, caspase-1, GSDMD, IL-1β, IL-18, and other downstream inflammatory factors; inflammatory responses were elevated; overexpression of miR-495 alleviated the tissue inflammation indicators miR-495 was downregulated in LPS-induced endometritis; its overexpression suppressed the NLRP3 inflammasome and pyroptosis, reducing IL-1β/IL-18 release and inflammation. miRNA interference, pyroptosis marker detection, RT-qPCR, western blot, ELISA Wu et al. 103 Human tissue observational human endometrium – N/A NLRP3, ASC, caspase-1, GSDMD, IL-1β, IL-18 inflammatory cell infiltration, fibrosis, and decreased endometrial receptivity NLRP3, caspase-1, and GSDMD levels were significantly upregulated, accompanied by increased IL-1β and IL-18 release RT-qPCR, GSDMD mRNA, western blot, IHC, ELISA Zheng et al. 104 Human tissue observational human endometrial – HRT cycle; biopsies at P + 3, P + 5, and P + 7 (P+5 = conventional WOI) inflammation-, immune response-, and cell death-related pathways abnormal immune and inflammatory signatures, such as upregulation of chemokines and inflammatory mediators endometrial transcriptome showed differential expression of immune- and cell-death-related genes. RNA extraction, RNA-seq, differentially expressed gene analysis, GO/KEGG pathway enrichment analysis Zhang et al. 105 Human tissue observational human endometrial – mid-secretory phase (5–8 days after LH peak; Noyes criteria confirmed) identified gene modules associated with inflammation, immunity, and metabolism. showed pronounced inflammation and immune activation characterized by enrichment of NLRP3-related pathways and associated with poorer pregnancy outcomes RNA-seq, differential expression and pathway enrichment analyses, retrospective analysis Yang et al. 106 Preclinical, animal model mouse endometritis model LPS N/A (animal study) NLRP3, caspase-1, IL-1β, IL-18, mRNA endometrial tissue showed reduced edema, congestion, and inflammatory cell infiltration; tissue structural damage was improved treatment with alloferon inhibited the NLRP3-caspase-1/IL-1β/IL-18 signaling pathway, significantly alleviating inflammation and improving tissue pathology western blot, ELISA Chen et al. 107 Preclinical – animal model C57BL/6 wild-type mice and NLRP3ˆ−/− (knockout) mice LPS N/A (animal study) NLRP3, ASC, caspase-1, IL-1β neutrophil infiltration, epithelial and stromal structural alterations, and increased MPO activity inflammation was significantly alleviated in NLRP3-deficient mice, with reduced IL-1β secretion and fewer pathological changes qPCR, western blot, ELISA, MPO activity assay, Yang et al. 108 Preclinical – animal model mouse LPS N/A (animal study) focusing on genes related to the PI3K-AKT (Akt1) and JAK-STAT pathways; measuring inflammatory cytokines IL-1β, TNF-α, and IL-6. uterine congestion, edema, neutrophil infiltration, and histologic damage leonurine modulated PI3K-AKT and other pathways, reducing inflammatory cytokines and histologic damage in endometritis RNA-seq, RT-qPCR, ELISA, H&E Shao et al. 109 Human tissue observational mouse – N/A (animal study) HMGB1 and GSDMD-NT (mRNA/protein); CD68 + macrophages; CD138 + plasma cells; inflammatory cytokines (IL-1β and IL-18). inflammatory infiltration and plasma cell increase were evident; GSDMD-NT co-localized with macrophages HMGB1 inhibition reduced tissue inflammation and pyroptosis RT-qPCR and western blot Shao et al. 109 Human tissue observational RIF biopsies mid-secretory human endometrium (RIF and controls) pyroptosis-related proteins: GSDMD-N, cleaved caspase-1, IL-18, IL-1β; CTSB, ADAM12, epiregulin (EREG) increased epithelial pyroptotic features, and higher GSDMD-N, caspase-1, IL-18, and IL-1β signals in RIF endometrium compared with fertile controls pyroptosis-related proteins were significantly elevated in RIF endometrium biopsies Li et al. 91 Human tissue observational RIF biopsies early proliferative, mid-proliferative, and mid-secretory endometrium (also decidua reported) NLRP3, EMT markers (E-cadherin, N-cadherin, vimentin), and receptivity markers (integrin β3, LIF, HOXA10); in vitro : IL-1β and IL-18 after NLRP3 manipulation NLRP3 expression in luminal epithelium was significantly lower in RIF endometrium than in fertile controls; EMT and receptivity markers were correspondingly impaired in RIF samples NLRP3 in RIF endometrium was associated with defective EMT and impaired receptivity, IHC, RT-qPCR, western blot, biopsies Cheng et al. 110 Preclinical – animal model mouse LPS N/A (animal study) NLRP3, ASC, caspase-1, IL-1β (protein & mRNA), MPO activity, neutrophil counts, histological injury score the LPS group showed endometrial edema, epithelial shedding, glandular structural damage, and extensive neutrophil infiltration LPS significantly activated NLRP3 inflammasome in the endometrium and increased IL-1 β levels H&E, ELISA, qPCR, western blot, MPO Yang et al. 108 Preclinical – animal model mouse LPS N/A (animal study) NLRP3, caspase-1, GSDMD, IL-1β (qPCR and western blot), MPO, IL-1β, IL-18, IL-6, TNF-α, NO the LPS group showed severe inflammatory infiltration of the endometrium; glandular and epithelial destruction; and ultrastructural features of cell swelling, membrane pore formation, and necrosis LPS induced the upregulation of NLPR3, caspase-1, and GSDMD mRNA and increased the secretion of IL-1 β/IL-18 in the endometrium H&E, ELISA, qPCR, western blot Xiong et al. 19 Preclinical – animal model mouse LPS N/A (animal study) TLR4, NF-κB, p65, NLRP3, caspase-1, GSDMD-N, IL-1β, IL-18 epithelial shedding, glandular necrosis, and increased infiltration of neutrophils; the inflammation degree and tissue structure damage in the PND treatment group were significantly reduced. LPS induced pyroptosis in endometrial tissue and mouse endometrial epithelial cells; both in vitro and in vivo H&E, ELISA, qPCR, western blot Shi et al. 111 Preclinical – animal model mouse LPS N/A (animal study) NLRP3, caspase-1, GSDMD, IL-1β, IL-18 thickening of uterine wall; intracavitary exudation; destruction of endometrial and glandular structures inhibition of NLRP3 inflammasome mediated pyroptosis: downregulation of NLRP3-caspase-1-GSDMD, IL-1 β, and IL-18 H&E, ELISA, qPCR, western blot, MPO Li et al. 112 Note: Definition of evidence levels: Human , human samples/clinical cohorts; Animal , animal models; In vitro , cell or tissue studies. The “Menstrual cycle phase at sampling” column applies only to human sample studies and is used to indicate the menstrual cycle stage or hormonal context at the time of specimen collection (e.g., natural cycle proliferative/secretory phase, LH + days, or HRT-cycle P + days). “N/A” indicates not applicable (animal models or in vitro experiments). Representative preclinical and clinical studies on pyroptosis in endometritis Note: Definition of evidence levels: Human , human samples/clinical cohorts; Animal , animal models; In vitro , cell or tissue studies. The “Menstrual cycle phase at sampling” column applies only to human sample studies and is used to indicate the menstrual cycle stage or hormonal context at the time of specimen collection (e.g., natural cycle proliferative/secretory phase, LH + days, or HRT-cycle P + days). “N/A” indicates not applicable (animal models or in vitro experiments). Across various PAMP-induced animal models of endometritis, activation of the NLRP3-caspase-1-GSDMD axis has been consistently observed. 113 Affected tissues in these models exhibit elevated levels of IL-1β and IL-18, along with hallmark histopathological features, including epithelial barrier disruption and neutrophil infiltration. 92 Notably, pharmacological inhibition of NLRP3 (e.g., MCC950) or genetic deletion of GSDMD alleviates inflammation and tissue injury in these animals, 107 suggesting that this pathway substantially contributes to disease progression in experimental settings. However, whether these interventional effects can be reproduced in human disease remains uncertain. In vitro studies have further identified macrophages and endometrial epithelial cells as key effector populations that undergo pyroptosis. HMGB1 promotes inflammasome activation by upregulating NLRP3 expression and facilitating inflammasome assembly through TLR4-NF-κB signaling, thereby driving caspase-1 activation, pore formation, and a self-sustaining proinflammatory feedback loop. 102 Increasing attention has also been directed toward epigenetic regulatory mechanisms. For example, miR-495-3p suppresses NLRP3 expression in vitro , reducing caspase-1 activity and GSDMD cleavage, ultimately attenuating pyroptosis and associated inflammatory responses. 103 These findings provide conceptual support for nucleic acid-based therapeutic strategies targeting pyroptotic pathways. Collectively, preclinical studies offer direct and mechanistic evidence for the potential role of pyroptosis in contributing to the pathogenesis of endometritis. Nevertheless, significant gaps remain between model systems and human disease owing to differences in model induction methods, species-specific immune biology, and the inherent heterogeneity of endometritis in patients. Compared with the abundance of preclinical data, studies directly examining pyroptosis in human endometritis remain relatively limited. Histological and molecular analyses of endometrial tissues from patients with confirmed endometritis have consistently demonstrated significantly elevated expression of key pyroptotic molecules—including NLRP3, activated caspase-1, and GSDMD-N—relative to healthy controls. 102 , 104 , 114 Immunohistochemical analysis reveals that these molecules localize predominantly to endometrial glandular epithelial and stromal cells, and their expression correlates positively with the degree of inflammatory cell infiltration, suggesting that pyroptosis may contribute to shaping the inflammatory microenvironment within the endometrium. 115 It is worth emphasizing that the diagnosis of chronic endometritis still largely relies on immunohistochemical identification of CD138 + plasma cells; however, this approach is limited by suboptimal inter-observer agreement and its inherently semi-quantitative nature, and it provides only a restricted, largely static readout of inflammatory “activity” and tissue injury severity over time. 116 In this context, pyroptosis-related molecules—such as NLRP3, active caspase-1, GSDMD-N, and IL-1β/IL-18—may offer a more objective index of inflammasome activation and lytic inflammatory responses, and thus hold potential as complementary biomarkers to CD138 for assessing inflammatory activity. 108 Nevertheless, most available clinical studies remain descriptive, focusing primarily on between-group differences, and there is a lack of systematic evidence from the same cohort linking pyroptosis markers with CD138 burden and clinical outcomes. Future investigations that rigorously document menstrual cycle stage and hormonal context and implement a combined strategy of “quantitative CD138 assessment plus pyroptosis-marker profiling” may help clarify the clinical utility and improve the objectivity of disease stratification. With the increasing application of multi-omics technologies, transcriptomic analyses of samples from patients with RIF, recurrent pregnancy loss (RPL), and specific infertility subgroups have further shown the enrichment of pathways related to inflammatory responses, cell death, and HMGB1-associated signaling. 117 Integrated analyses indicate that the upregulation of core pyroptosis-related genes—including NLRP3 , CASP1 , and GSDMD —is associated with specific inflammatory endometrial phenotypes and adverse reproductive outcomes, 105 , 106 , 118 raising the possibility that dysregulated pyroptosis may constitute a risk factor underlying these reproductive abnormalities. However, most existing clinical studies are correlational in nature, making it difficult to infer causal contributions of pyroptotic pathways to disease progression in patients. Limited sample sizes, substantial etiological heterogeneity, and the lack of prospective cohorts or interventional studies further constrain the robustness of current conclusions. In addition, most existing clinical studies have relied on bulk tissue-level measurements or limited immunohistochemical analyses, which makes it difficult to precisely delineate the cellular sources of pyroptosis-related signals. 119 Distinct cell types may play divergent pathological roles: epithelial-cell pyroptosis is more likely to be linked to barrier disruption and DAMP leakage, stromal cells may contribute to inflammatory microenvironment remodeling, whereas inflammasome activation in immune cells may dominate IL-1β/IL-18 release and the amplification of inflammatory responses. 120 , 121 , 122 However, systematic human evidence delineating these cell type-specific contributions remains insufficient, underscoring the need for integrative single-cell and spatially resolved analyses to resolve these questions. The initiation and regulation of pyroptosis rely on the coordinated activity of multiple signaling pathways, among which the NLRP3 inflammasome serves as a central regulatory hub. 123 NLRP3 activation typically follows a well-established two-signal model: the first signal, mediated by TLR4 and NF-κB, induces the transcription of NLRP3 and pro-IL-1β; the second signal, triggered by ROS production, K + efflux, and mitochondrial injury, promotes inflammasome assembly and subsequent caspase-1 activation. 124 In vitro and in vivo studies indicate that enhancing mitophagy to mitigate mitochondrial stress may suppress NLRP3 activation and, in turn, reduce pyroptotic cell death. 125 In animal models of endometritis, selective pharmacologic inhibition of NLRP3 was reported to markedly attenuated inflammation, further supporting its role as a critical regulatory node. 112 Beyond NLRP3, the PI3K-AKT pathway influences pyroptotic sensitivity by modulating cellular metabolism and ROS generation. 126 Elevated PI3K-AKT activity in human endometrial tissue samples has been associated with sustained inflammatory responses. 109 Additionally, the HMGB1-TLR4 axis, a prototypical DAMP-mediated signaling pathway, can potentiate inflammasome activation and amplify pyroptotic responses, potentially contributing to the chronicity observed in some cases of endometritis. 127 Other inflammatory signaling pathways—including STING, MAPK, JAK, and STAT—also intersect with pyroptosis regulation. 128 , 129 For instance, MAPK pathways can augment NLRP3 transcription, whereas JAK-STAT signaling may help maintain the prolonged expression of proinflammatory genes—a feature consistent with the oxidative stress frequently observed in endometritis. 53 , 54 , 129 Necroptosis and pyroptosis often occur in parallel within inflamed tissues, and crosstalk between these pathways may amplify cell death and tissue injury 130 , 131 ( Figure 5 ). These interactions highlight the need for multi-omics approaches and multi-model comparative strategies to dissect the relative contributions of different forms of PCD. Collectively, preclinical studies provide mechanistic evidence that pyroptosis can drive inflammatory responses, while human tissue and cohort data suggest associations between pyroptosis, inflammatory endometrial phenotypes, and adverse reproductive outcomes. Nevertheless, a substantial gap remains between mechanistic inference and clinical causality. Future research must incorporate larger sample sizes and rigorously designed prospective and interventional studies to delineate the precise role of pyroptotic pathways in human endometritis and to support the development of targeted therapeutic strategies. Figure 5 Cross-evidence-level mechanistic integration of key signaling pathways involved in pyroptosis in endometritis Upstream stimuli including pathogen infection (e.g., LPS or PAMPs), DAMPs (HMGB1, ROS, mtDNA), and barrier disruption can induce TLR4-NF-κB priming, thereby upregulating NLRP3 and pro-IL-1β and establishing the prerequisite for subsequent inflammasome activation. Upon the second signal (ROS generation, K + efflux, and mitochondrial damage), the canonical NLRP3 inflammasome (NLRP3-ASC-caspase-1) assembles and becomes activated, leading to GSDMD cleavage, membrane pore formation, and release of proinflammatory mediators such as IL-1β and IL-18, which collectively amplify local inflammation and contribute to barrier disruption and fibrosis. Meanwhile, cytosolic LPS can trigger the noncanonical pathway by activating caspase-4/5 in humans or caspase-11 in mice, thereby driving GSDMD-dependent pyroptotic responses. In addition, crosstalk between inflammatory signaling pathways including STING, MAPK, JAK, and STAT may amplify pyroptosis by enhancing NLRP3 transcription and sustaining proinflammatory gene expression. Necroptosis (RIPK1/3-MLKL) can be co-activated and interact with pyroptosis, further exacerbating cell death and tissue injury. The figure was created with BioRender.com . Cross-evidence-level mechanistic integration of key signaling pathways involved in pyroptosis in endometritis Upstream stimuli including pathogen infection (e.g., LPS or PAMPs), DAMPs (HMGB1, ROS, mtDNA), and barrier disruption can induce TLR4-NF-κB priming, thereby upregulating NLRP3 and pro-IL-1β and establishing the prerequisite for subsequent inflammasome activation. Upon the second signal (ROS generation, K + efflux, and mitochondrial damage), the canonical NLRP3 inflammasome (NLRP3-ASC-caspase-1) assembles and becomes activated, leading to GSDMD cleavage, membrane pore formation, and release of proinflammatory mediators such as IL-1β and IL-18, which collectively amplify local inflammation and contribute to barrier disruption and fibrosis. Meanwhile, cytosolic LPS can trigger the noncanonical pathway by activating caspase-4/5 in humans or caspase-11 in mice, thereby driving GSDMD-dependent pyroptotic responses. In addition, crosstalk between inflammatory signaling pathways including STING, MAPK, JAK, and STAT may amplify pyroptosis by enhancing NLRP3 transcription and sustaining proinflammatory gene expression. Necroptosis (RIPK1/3-MLKL) can be co-activated and interact with pyroptosis, further exacerbating cell death and tissue injury. The figure was created with BioRender.com .

Y.L. performed the literature search, synthesized evidence, prepared the figures, and wrote the initial manuscript draft; G.W. and X.Q. contributed to data organization, figure refinement, and manuscript editing; G.H. participated in literature screening and contributed to conceptual discussions, particularly regarding pyroptosis-related inflammatory responses and epithelial barrier dysfunction; S.Z. supervised the project and guided the manuscript structure; H.L. co-supervised the work and critically revised the manuscript. All authors have contributed to data interpretation and manuscript editing and approved the final version.

Despite the growing body of literature examining the role of pyroptosis in endometritis, current evidence remains limited by study quality, experimental design, and translational applicability. The conclusions synthesized in this review are, therefore, constrained by these factors and should be interpreted with appropriate consideration of evidence levels and methodological context. Most studies referenced in the current review have relied on in vitro systems and animal models. Although these approaches provide essential mechanistic insights into pyroptotic signaling, their findings may not fully translate to human disease. At present, investigations of key components—including the NLRP3 inflammasome, caspase-1/4/5/11, and GSDMD—remain largely preclinical, lacking large-scale, systematic clinical validation. This gap represents a major limitation for translational application. Furthermore, species-specific differences in the noncanonical pathway (caspase-4/5 in humans vs. caspase-11 in mice) restrict the extrapolation of animal data. In addition, the specific contributions of different endometrial cell populations—including epithelial, stromal, and immune cells—to pyroptotic activation and inflammatory amplification have not been comprehensively delineated. The complex interplay and plasticity among various forms of PCD—such as apoptosis, necroptosis, and ferroptosis—pose additional challenges. These interactions suggest that targeting a single molecule or pathway may be insufficient for achieving effective inflammatory control and may even provoke compensatory mechanisms or immune dysregulation. Given these limitations, future studies should advance in several key directions. (1) Strengthening clinical evidence: Large-scale, multi-center, prospectively designed studies with clearly defined endometritis populations are urgently required to establish causal associations between pyroptosis-related molecules—such as NLRP3, CASP1, and GSDMD—and disease severity or reproductive outcomes. (2) Integrating multi-omics approaches for mechanistic resolution: Single-cell sequencing, spatial transcriptomics, and multi-omics integration will be essential for delineating the dynamic inflammatory microenvironment of the endometrium and mapping pyroptotic signaling at higher resolution. (3) Developing more physiologically relevant models: Organoids, endometrium-on-a-chip platforms, and humanized animal models may offer improved physiological relevance for evaluating pyroptotic pathways within complex tissue contexts. (4) Evaluating therapeutic feasibility and safety: Potential interventions—such as NLRP3 inhibitors, caspase-1 inhibitors, and miRNA delivery systems—require rigorous mechanistic justification, comprehensive toxicological evaluation, and systematic preclinical efficacy testing before clinical translation. From a translational perspective, pyroptosis-associated molecules hold considerable promise as diagnostic biomarkers, tools for disease stratification, and potential therapeutic targets. In the near term, candidate molecules such as NLRP3, CASP1, and GSDMD may be incorporated into prospective cohort studies to assess their predictive value for diagnosing endometritis and for identifying risks associated with reproductive disorders such as RIF and RPL. In the longer term, if future preclinical and human mechanistic studies substantiate a core pathogenic role for pyroptosis, novel therapeutic strategies may emerge. These could include small-molecule inhibitors targeting pyroptotic pathways, antagonists modulating the HMGB1-TLR4 axis, and miRNA-based precision therapeutics. Nevertheless, potential clinical applications must be grounded in rigorous safety assessment and validated through well-designed clinical trials.

The canonical pyroptotic pathway is defined by the inflammasome assembly and subsequent activation of caspase-1. 20 Inflammasomes are cytosolic multi-protein complexes typically composed of a pattern recognition receptor (PRR), the adaptor protein (ASC)-apoptosis-associated speck-like protein containing a CARD, and the effector protease caspase-1. 21 Common PRRs include NLRP3, AIM2, and NLRC4; AIM2 primarily senses cytosolic double-stranded DNA, NLRC4 recognizes bacterial flagellin and components of the type III secretion system, whereas NLRP3 integrates a wide range of cellular stress signals. 22 Activation of NLRP3 generally follows a “two-step model.” During the priming phase, signaling pathways such as Toll-like receptor (TLR)-nuclear factor kappa B (NF-κB) induce the transcriptional upregulation of NLRP3 and pro-IL-1β. The activation phase is initiated by triggers including K + efflux, increased reactive oxygen species (ROS), mitochondrial DNA release, lysosomal rupture, and ATP-P2X7 signaling, all of which promote the inflammasome assembly. 23 These stimuli are not exhaustive, and variations exist across cell types and environmental contexts. Upon PRR activation, conformational changes expose interaction domains and drive NLRP3-ASC oligomerization, which subsequently recruits pro-caspase-1 and facilitates its autocatalytic cleavage into active caspase-1. 23 Activated caspase-1 executes two critical reactions. First, caspase-1 cleaves pro-IL-1β and pro-IL-18 into their mature, secreted forms. Second, caspase-1 cleaves GSDMD to release the N-terminal fragment (N-GSDMD), which oligomerizes within the plasma membrane to form ∼10–15 nm pores. These pores disrupt ionic homeostasis and cellular osmotic balance, ultimately leading to lytic cell death. 24 , 25 , 26 This terminal event is accompanied by the extracellular release of IL-1β, IL-18, and DAMPs, thereby amplifying local inflammatory responses 27 ( Figure 1 ). Depending on the context, including infectious or sterile inflammation, canonical pyroptosis may function as a host-protective mechanism or as a driver of collateral tissue injury, which reflects its characteristic “defense versus damage” duality. 28 In patient endometrial tissues (human samples) and in vitro LPS-stimulated endometrial cell models, increased expression of inflammasome-related molecules (e.g., NLRP3 and CASP1) and proinflammatory cytokines has been reported, while mechanistic evidence for inflammasome activation and downstream pyroptotic execution has largely been derived from animal and in vitro studies. 29 However, these findings are largely associative, and the causal contribution of canonical pyroptosis to disease initiation or persistence requires verification through prospective and interventional studies. Figure 1 Schematic of the molecular mechanisms underlying canonical pyroptosis PAMPs or DAMPs initially engage TLR4 and NF-κB signaling to initiate the priming step, thereby upregulating the transcription of NLRP3 and pro-IL-1β. Subsequent assembly of the NLRP3 inflammasome occurs through the recruitment of the adaptor ASC and pro-caspase-1. Activated caspase-1 cleaves pro-IL-1β and pro-IL-18 into their mature cytokine forms, while also processing GSDMD to release the pore-forming N-terminal fragment (N-GSDMD). Oligomerized N-GSDMD inserts into the plasma membrane to form pores, inducing K + efflux and Ca 2+ /Cl − influx and facilitating the extracellular release of IL-1β, IL-18, and DAMPs. These events culminate in lytic, proinflammatory pyroptotic cell death. The figure was created with BioRender.com . PAMPs, pattern-associated molecular patterns; DAMPs, damage-associated molecular patterns; GSDMD, gasdermin D. Schematic of the molecular mechanisms underlying canonical pyroptosis PAMPs or DAMPs initially engage TLR4 and NF-κB signaling to initiate the priming step, thereby upregulating the transcription of NLRP3 and pro-IL-1β. Subsequent assembly of the NLRP3 inflammasome occurs through the recruitment of the adaptor ASC and pro-caspase-1. Activated caspase-1 cleaves pro-IL-1β and pro-IL-18 into their mature cytokine forms, while also processing GSDMD to release the pore-forming N-terminal fragment (N-GSDMD). Oligomerized N-GSDMD inserts into the plasma membrane to form pores, inducing K + efflux and Ca 2+ /Cl − influx and facilitating the extracellular release of IL-1β, IL-18, and DAMPs. These events culminate in lytic, proinflammatory pyroptotic cell death. The figure was created with BioRender.com . PAMPs, pattern-associated molecular patterns; DAMPs, damage-associated molecular patterns; GSDMD, gasdermin D. The noncanonical pyroptotic pathway is initiated by the direct sensing of cytosolic LPS by caspase-4/5 in humans or caspase-11 in mice. In this process, the caspase CARD domain binds to LPS, driving enzyme dimerization and autoactivation. 30 Activated caspase-4/5/11 subsequently cleaves GSDMD, releasing the N-GSDMD, which oligomerizes within the plasma membrane to form cytolytic pores and induce lytic, proinflammatory cell death ( Figure 2 ). 31 , 32 , 33 , 34 , 35 Although this pathway does not require upstream inflammasome assembly, it is functionally coupled to the canonical axis downstream. Ion flux disturbances, particularly K + efflux, induced by N-GSDMD pores serve as secondary triggers for NLRP3 inflammasome assembly and caspase-1 activation, thereby enabling the maturation and secretion of IL-1β and IL-18 and amplifying the inflammatory response. 36 , 37 Species-specific differences exist regarding the key caspases (human caspase-4/5 vs. murine caspase-11). Moreover, cytosolic access of LPS typically depends on processes such as endocytosis, vesicular rupture, and guanylate-binding protein (GBP)-mediated membrane disruption, 38 and these mechanisms vary across cell types and stimulation contexts. 39 In the setting of endometritis, common Gram-negative pathogens (e.g., Escherichia coli and Pseudomonas aeruginosa ) can provide priming signals via TLR4 and NF-κB—thereby upregulating NLRP3 and pro-IL-1β transcription—while cytosolic internalization of their LPS activates the noncanonical caspase-4/5 (or murine caspase-11) pathway. This activation synergizes with the canonical inflammasome axis to intensify local inflammation. 37 , 40 However, current evidence from human tissue samples is largely associative. Critical mechanistic questions—such as the determinants of LPS cytosolic entry, the activation thresholds of the pathway, and its temporal dynamics—remain unresolved, and causal relationships require validation through prospective and interventional studies. Figure 2 Schematic of the noncanonical pyroptosis pathway Upon entering the cytosol, LPS derived from Gram-negative bacteria directly induces the autoactivation of caspase-4/5 in humans or caspase-11 in mice, leading to the cleavage of GSDMD and the release of its pore-forming N-terminal fragment (N-GSDMD). Oligomerized N-GSDMD inserts into the plasma membrane to form transmembrane pores, triggering lytic and proinflammatory pyroptotic cell death. The resulting membrane permeabilization drives K + efflux and other ionic fluxes, which secondarily activate the NLRP3-ASC-pro-caspase-1 complex. Activated caspase-1 subsequently processes pro-IL-1β and pro-IL-18 into their mature forms, thus amplifying the canonical inflammasome pathway. Although this pathway initiates independently of the inflammasome assembly, it converges with the canonical pathway at downstream signaling steps. The figure was created with BioRender.com . LPS, lipopolysaccharide; GSDMD, gasdermin D. Schematic of the noncanonical pyroptosis pathway Upon entering the cytosol, LPS derived from Gram-negative bacteria directly induces the autoactivation of caspase-4/5 in humans or caspase-11 in mice, leading to the cleavage of GSDMD and the release of its pore-forming N-terminal fragment (N-GSDMD). Oligomerized N-GSDMD inserts into the plasma membrane to form transmembrane pores, triggering lytic and proinflammatory pyroptotic cell death. The resulting membrane permeabilization drives K + efflux and other ionic fluxes, which secondarily activate the NLRP3-ASC-pro-caspase-1 complex. Activated caspase-1 subsequently processes pro-IL-1β and pro-IL-18 into their mature forms, thus amplifying the canonical inflammasome pathway. Although this pathway initiates independently of the inflammasome assembly, it converges with the canonical pathway at downstream signaling steps. The figure was created with BioRender.com . LPS, lipopolysaccharide; GSDMD, gasdermin D. GSDME (also known as DFNA5), located on chromosome 7p15.3, was initially identified in association with hereditary hearing loss and was not considered to participate in inflammatory processes. 41 , 42 Subsequent studies, however, revealed that GSDME functions as a regulatory node linking apoptosis and pyroptosis. 43 Upon caspase-3 activation, GSDME is cleaved to generate the pore-forming N-terminal fragment (N-GSDME), which oligomerizes within the plasma membrane to form lytic pores, disrupts ionic homeostasis, and induces osmotic imbalance, ultimately triggering lytic and proinflammatory cell death 44 , 45 , 46 ( Figure 3 ). Unlike the canonical inflammasome-caspase-1-GSDMD axis, this pathway is primarily driven by upstream apoptotic signaling and does not depend on inflammasome activation for initiation. Its proinflammatory effects arise predominantly from pore-mediated release of DAMPs and cytosolic components, whereas the maturation of IL-1β and IL-18 still requires caspase-1. Consequently, GSDME mainly facilitates cytokine release rather than processing. 47 , 48 In certain contexts, the microenvironmental perturbations caused by N-GSDME pores may indirectly couple to NLRP3-caspase-1 activation, although current evidence remains limited. 49 , 50 Figure 3 Schematic of GSDME-mediated pyroptosis-like cell death In endometrial cells, caspase-3 cleaves GSDME (DFNA5) to generate the pore-forming N-GSDME fragment, which oligomerizes within the plasma membrane and induces ion flux imbalance and osmotic dysregulation, ultimately leading to lytic, proinflammatory cell death. The membrane pores facilitate the extracellular release of DAMPs (such as HMGB1) and intracellular contents, thereby amplifying inflammatory signaling. The maturation of IL-1β and IL-18, however, is executed by the NLRP3-caspase-1 axis; the GSDME pathway primarily enhances cytokine release, rather than cytokine processing. This form of cell death exhibits threshold-dependent plasticity: high GSDME expression and strong caspase-3 activation favor pyroptosis-like lysis, whereas low GSDME expression or weaker upstream signals preferentially result in apoptosis. This figure represents a conceptual schematic of the described GSDME-mediated cell-death pathway. The figure was created with BioRender.com . GSDME, gasdermin E; DAMPs, damage-associated molecular patterns; HMGB1, high-mobility group box 1. Schematic of GSDME-mediated pyroptosis-like cell death In endometrial cells, caspase-3 cleaves GSDME (DFNA5) to generate the pore-forming N-GSDME fragment, which oligomerizes within the plasma membrane and induces ion flux imbalance and osmotic dysregulation, ultimately leading to lytic, proinflammatory cell death. The membrane pores facilitate the extracellular release of DAMPs (such as HMGB1) and intracellular contents, thereby amplifying inflammatory signaling. The maturation of IL-1β and IL-18, however, is executed by the NLRP3-caspase-1 axis; the GSDME pathway primarily enhances cytokine release, rather than cytokine processing. This form of cell death exhibits threshold-dependent plasticity: high GSDME expression and strong caspase-3 activation favor pyroptosis-like lysis, whereas low GSDME expression or weaker upstream signals preferentially result in apoptosis. This figure represents a conceptual schematic of the described GSDME-mediated cell-death pathway. The figure was created with BioRender.com . GSDME, gasdermin E; DAMPs, damage-associated molecular patterns; HMGB1, high-mobility group box 1. The cell-death modality induced by caspase-3 is influenced by GSDME abundance: when GSDME expression is sufficient, and caspase-3 activation is robust, apoptosis that would otherwise be “silent” can shift toward GSDME-mediated, pyroptosis-like lytic death 51 ; conversely, low GSDME expression favors nonlytic apoptosis. 52 This switch from apoptosis to pyroptosis has been demonstrated in models involving chemotherapeutic agents such as cisplatin and taxanes and is associated with reinforcement of inflammatory microenvironments. 46 , 53 , 54 Meanwhile, membrane repair pathways—particularly those mediated by (ESCRT-III)-endosomal sorting complex required for transport III—can partially constrain overt membrane rupture, and their activity may determine whether cells survive following N-GSDME pore formation. 55 In endometritis, available evidence suggests that endometritis-related stimuli—including bacterial components, toxin-induced oxidative stress, proinflammatory cytokines, and selected pharmacological exposures—can activate caspase-3, thereby providing the biological conditions required for GSDME cleavage and pyroptosis-like death. 56 This process may potentiate DAMP release, amplify inflammatory response, and compromise epithelial barrier integrity. 57 However, direct causal evidence from human samples remains limited. Most current insights into the GSDME expression patterns, cleavage status, and associations with inflammatory severity and reproductive outcomes are derived from in vitro and animal studies. Establishing causality will require the use of human-derived models and well-designed prospective interventional investigations. Finally, it should be emphasized that caspase-3 activation does not necessarily equate to pathological inflammatory amplification. Caspase-3 is physiologically engaged in cyclical apoptosis and tissue renewal during endometrial remodeling and menstrual shedding. 58 Therefore, when discussing caspase-3/GSDME-dependent pyroptosis-like lytic death, it is essential to distinguish physiological apoptosis from pathological lytic cell death. 59 Unlike cyclic apoptosis, which typically preserves plasma membrane integrity and is accompanied by limited inflammatory release, extensive GSDME cleavage and pore formation may promote the extracellular leakage of DAMPs and thereby amplify inflammatory cascades. 60 In human samples, assessment of caspase-3 activation alone is insufficient to infer pathological status; it should be interpreted in conjunction with GSDME cleavage, indicators of membrane integrity/lysis, and the degree of inflammatory cell infiltration, while also accounting for the menstrual cycle stage of the specimen. 61 Future studies should, therefore, co-profile apoptotic and lytic cell-death markers under rigorously annotated cycle contexts to avoid misclassifying physiological remodeling as inflammation-associated lytic injury. The activity of pyroptosis-related proteins is governed not only by proteolytic cleavage but also by a spectrum of site-specific post-translational modifications (PTMs) ( Figure 4 ). These modifications regulate protein stability, subcellular localization, assembly competence, oligomerization potential, and pore-formation thresholds, thereby shaping the magnitude and duration of downstream inflammatory cascades. 62 At the effector level, GSDMD undergoes multiple PTMs, including ubiquitination, deubiquitination, phosphorylation, and acetylation. 63 Distinct ubiquitin chain types (e.g., K48- versus K63-linked) and specific deubiquitinases (DUBs) modulate GSDMD turnover, membrane association, and oligomerization capacity. Inhibition of GSDMD acetylation or modulation of key phosphorylation sites is associated with reduced pore formation and attenuated cell lysis in preclinical models. 64 Evidence for PTMs on GSDME is comparatively limited; however, in vitro studies suggest that ubiquitination and phosphorylation may influence the stability and membrane targeting of N-GSDME, indicating a potential post-cleavage regulatory layer that imposes a secondary activation threshold. 65 Figure 4 PTMs of pyroptosis-related proteins In the pyroptotic pathway, key molecules such as GSDMD, GSDME, and NLRP3 are finely regulated by site-specific PTMs, including ubiquitination, phosphorylation, and acetylation. K48-linked ubiquitination facilitates GSDMD degradation, whereas K63-linked chains promote NLRP3 assembly and signal amplification. Deubiquitination of distinct chain types modulates membrane association and pore-formation thresholds. Phosphorylation, dephosphorylation, and stress-associated modifications of NLRP3 regulate its assembly efficiency with ASC and caspase-1. Acetylation and phosphorylation of GSDME influence the stability, membrane localization, and oligomerization of N-GSDME. Collectively, these PTMs determine protein stability, subcellular localization, pore-forming capacity, and inflammatory amplification, thereby shaping the overall magnitude of pyroptotic signaling. The figure was created with BioRender.com . PTMs, post-translational modifications; GSDMD, gasdermin D; GSDME, gasdermin E. PTMs of pyroptosis-related proteins In the pyroptotic pathway, key molecules such as GSDMD, GSDME, and NLRP3 are finely regulated by site-specific PTMs, including ubiquitination, phosphorylation, and acetylation. K48-linked ubiquitination facilitates GSDMD degradation, whereas K63-linked chains promote NLRP3 assembly and signal amplification. Deubiquitination of distinct chain types modulates membrane association and pore-formation thresholds. Phosphorylation, dephosphorylation, and stress-associated modifications of NLRP3 regulate its assembly efficiency with ASC and caspase-1. Acetylation and phosphorylation of GSDME influence the stability, membrane localization, and oligomerization of N-GSDME. Collectively, these PTMs determine protein stability, subcellular localization, pore-forming capacity, and inflammatory amplification, thereby shaping the overall magnitude of pyroptotic signaling. The figure was created with BioRender.com . PTMs, post-translational modifications; GSDMD, gasdermin D; GSDME, gasdermin E. At the upstream platform level, NLRP3 assembly and disassembly are regulated bidirectionally by ubiquitination and deubiquitination, where K48-linked chains typically promote degradation, whereas K63-linked chains facilitate signaling and inflammasome assembly. Additional PTMs such as phosphorylation, dephosphorylation, and stress-related modifications further modulate NLRP3 coupling efficiency with ASC and caspase-1, as well as its temporal and spatial distribution. 66 Phosphorylation or SUMOylation of ASC and caspase-1 has also been proposed to fine-tune speck formation and enzymatic activity; however, the modification sites and functional consequences in endometrium-relevant cell types remain to be systematically elucidated. 67 In the context of endometritis, such PTMs may define the activation thresholds for GSDMD- or GSDME-mediated pore formation and NLRP3 inflammasome assembly, thereby contributing to the persistence and amplification of chronic inflammation. 68 , 69 Given that current evidence is derived primarily from preclinical studies, a site-resolved PTM atlas and functional causal analyses in human endometrial tissues remain unavailable. Future research should prioritize mapping modification sites and validating their mechanistic roles.

Given the central role of pyroptosis in the onset and progression of endometritis, multiple molecular components and signaling pathways have emerged as promising therapeutic targets. These strategies can be broadly categorized into molecularly targeted interventions, signaling pathway modulation, miRNA-based regulation, and pharmacological approaches. (1) Molecular targeting strategies: In an LPS-induced mouse endometritis model ( in vivo ) and mouse endometrial epithelial cells ( in vitro ), the NLRP3 inflammasome acts as a key regulator of pyroptosis and is implicated in inflammatory endometrial injury. 132 Selective NLRP3 inhibitors—such as dapansutrile and selnoflast—have been shown to markedly suppress the release of IL-1β and IL-18, thereby mitigating inflammatory responses. 133 , 134 These compounds inhibit NLRP3 ATPase activity and block interactions with ASC and caspase-1, thereby preventing inflammasome assembly and activation. Caspase-1 subsequently cleaves GSDMD to generate the N-terminal fragment (GSDMD-NT), which perforates the plasma membrane and drives the release of inflammatory mediators, thereby amplifying pyroptosis. 135 , 136 Although the direct application of caspase-1 inhibitors or GSDMD blockers in endometritis has not yet been reported, studies in other inflammatory and gynecologic disorders, such as endometrial cancer and peritonitis, have demonstrated that these approaches can significantly reduce IL-1β and IL-18 secretion and ameliorate tissue injury. 114 , 137 The selective caspase-1 inhibitor VX-765 has shown therapeutic efficacy in several inflammatory models. 138 , 139 Moreover, beyond the canonical NLRP3-caspase-1-GSDMD axis, the noncanonical pathway also contributes to the pathogenesis of endometritis. 140 Cytosolic LPS directly activates caspase-4/5 in humans or caspase-11 in mice, inducing GSDMD cleavage and pyroptosis. 141 Small-molecule caspase inhibitors such as INF200 may, therefore, represent an additional therapeutic avenue. (2) Modulation of upstream signaling pathways: Several signaling cascades regulate pyroptosis. The PI3K-AKT pathway coordinates cell survival, metabolism, and immune responses, and its activation promotes pyroptosis by modulating ROS production and NF-κB signaling. 142 Pharmacologic inhibition of the PI3K-AKT pathway significantly reduces inflammatory cell infiltration in endometritis models. HMGB1, a prototypical DAMP, activates NLRP3 through TLR4 engagement and enhances pyroptotic signaling. 143 , 144 Blocking HMGB1 release or inhibiting TLR4 signaling—via anti-HMGB1 antibodies or TLR4 antagonists—attenuates inflammation in experimental endometritis. The JAK-STAT pathway also plays a pivotal role in immune cell activation and cytokine production 145 ; its activation enhances NLRP3 inflammasome assembly and pyroptosis. 146 JAK inhibitors such as baricitinib have shown potential in reducing pyroptosis-associated inflammation in endometritis models. 147 , 148 (3) miRNA-mediated regulation: miRNAs, as key post-transcriptional regulators, are increasingly being recognized as critical modulators of pyroptotic pathways. Among them, miR-495-3p was reported to directly suppress NLRP3 expression, reduce pyroptotic signaling, and alleviate inflammatory responses in endometritis models. 149 These findings suggest that miRNAs may serve not only as therapeutic agents but also as diagnostic biomarkers. (4) Pharmacological interventions: Nonsteroidal anti-inflammatory drugs (NSAIDs) primarily exert anti-inflammatory effects by inhibiting cyclooxygenase (COX) activity and reducing prostaglandin synthesis. 2 , 150 Recent studies further suggest that NSAIDs can inhibit ROS generation and suppress NLRP3 inflammasome activation, thereby attenuating pyroptosis. 151 Classic NSAIDs such as ibuprofen and naproxen may, therefore, have therapeutic value in endometritis. 152 Hydrogen therapy has garnered interest as a potent antioxidant and anti-inflammatory strategy. Molecular hydrogen reduces NLRP3 activation and pyroptosis by inhibiting ROS production. 153 , 154 Although direct evidence in endometritis models remains limited, existing findings support the potential of hydrogen to promote endometrial tissue repair and functional recovery. 155 , 156 Similarly, hydrogen sulfide (H 2 S), another endogenous gaseous signaling molecule, exhibits anti-inflammatory and tissue-protective effects. H 2 S inhibits NLRP3 activation and reduces pyroptosis, potentially facilitating endometrial tissue regeneration; however, its efficacy in endometritis requires further experimental validation. 157 Collectively, these findings suggest that developing therapeutic strategies that inhibit the NLRP3-caspase-1-GSDMD axis, modulate upstream signaling pathways, utilize miRNA-based regulation, and employ pharmacological agents represents a promising direction for innovative endometritis treatment. However, translating these experimental advances into clinical practice will require substantial additional work, including rigorous preclinical validation, pharmacokinetic studies, and well-designed clinical trials.

Endometritis is a common yet frequently underdiagnosed inflammatory disorder of the female reproductive tract, traditionally classified into acute and chronic forms based on clinical course and histopathological features. 1 , 2 , 3 With the increased use of assisted reproductive technologies, the clinical significance of endometritis has received attention due to its detrimental effects on embryo implantation and pregnancy outcomes. 4 Epidemiological data indicate that the prevalence of endometritis ranges from 10% to 30% among infertile women and exceeds 40% among patients with recurrent implantation failure (RIF). 5 , 6 However, nonspecific clinical manifestations, interobserver variability in CD138 immunohistochemical interpretation—the current diagnostic gold standard—and frequent post-treatment recurrence collectively indicate that the underlying pathogenic mechanisms remain unclear. 3 Traditionally, infection, endometrial injury following intrauterine procedures, and immune dysregulation have been regarded as the principal etiologic factors in endometritis. 7 Nevertheless, a definitive pathogen cannot be identified in up to 20%–30% of cases, 8 strongly implying that noninfectious contributors also play an essential role. As a cyclically remodeling tissue that must continuously balance immune tolerance and activation, the endometrium is particularly susceptible to disruptions in inflammatory forms of programmed cell death (PCD). 9 Among the various PCD modalities, pyroptosis has emerged as a central focus because it uniquely integrates lytic cell death with potent inflammatory amplification. 10 , 11 Canonically, pyroptosis is initiated by inflammasome activation, such as caspase-1 downstream of (NLRP3)-NOD-like receptor family pyrin domain-containing 3, or by lipopolysaccharide (LPS)-induced activation of caspase-4/5/11, leading to the cleavage of gasdermin (GSDM) family proteins (e.g., gasdermin D [GSDMD] and gasdermin E [GSDME]). This cleavage forms membrane pores and enables the release of proinflammatory cytokines, including interleukin 1β (IL-1β) and IL-18. 12 , 13 , 14 Aberrant activation of inflammasomes, such as absent in melanoma 2 (AIM2), NLRP3, and NLRC4, has been observed in multiple chronic inflammatory and gynecologic disorders, including endometriosis, polycystic ovary syndrome, and ovarian cancer. 15 , 16 , 17 In the context of endometritis, both endometrial epithelial cells and infiltrating immune cells can sense pathogen-associated molecular patterns (PAMPs) or damage-associated molecular patterns (DAMPs) and activate the inflammasome-caspase-GSDM signaling axes, thereby amplifying local inflammation and potentially contributing to disease chronicity. 17 Despite these mechanistic insights, evidence linking pyroptosis to endometritis remains predominantly preclinical, with limited human cohort data and insufficient causal inference. 18 Moreover, the reciprocal regulation among pyroptosis, apoptosis, ferroptosis, and necroptosis remains poorly delineated. 19 Key questions remain regarding whether pyroptosis functions as a primary driver, a downstream consequence, or a context-dependent modulator of disease progression. Therefore, this review aims to: (1) systematically summarize the canonical and noncanonical molecular mechanisms of pyroptosis and its regulatory networks; (2) delineate research progress across distinct cell types and disease stages in endometritis; (3) evaluate the interplay between pyroptosis and other PCD modalities and the associated pathological implications; and (4) discuss therapeutic opportunities targeting pyroptotic pathways, while highlighting the emerging value of multi-omics and spatial-omics technologies in future investigations. This review integrates current evidence to provide new mechanistic perspectives on the molecular pathology of endometritis and a conceptual foundation for improving diagnostic precision and developing targeted therapeutic strategies.

The authors declare that they have no conflict of interest.

The authors have no acknowledgments to declare.