Plasma Exosome-derived MicroRNAs profiles in patients with serofast syphilis

Background: Syphilis is a bacterial STI caused by Treponema pallidum that results in substantial morbidity and mortality. Currently, it has been suggested that exosomes (Exo) may play a possible role as novel biomarkers for the detection of infectious diseases. Here, we investigated the exosomal miRNA derived from plasma in syphilis, aimed to help in the diagnosis and prognosis of serofast syphilis. Methods: A discovery cohort was used to investigate exosomal miRNAs that vary across the different subjects of participants. Exosomal miRNAs were isolated from peripheral plasma obtained at secondary syphilis(SS,n=5), serofast(SF,n=6),healthy control(HC,n=5) and serologically cured syphilis patients(SC,n=4), and microarray analysis was performed. A validation cohort was used to confirm the selected differential expression of exosomal miRNAs by real-time fluorescence quantitative PCR (RT-qPCR). ROC analysis was used to evaluate the differentiation power of these miRNAs in syphilis diagnosis. Results: The microarray result revealed a specific plasma exosomal miRNA expression profile in serofast syphilis. 44 miRNAs showed significant differences between serofast and secondary syphilis, and 12 miRNAs were differentially expressed between serofast and serologically cured syphilis patients. MiR-1273g-3p, miR-4485-5p, miR-197-3p, miR- 1908-3p were significantly upregulated in syphilis patients in a stage-specific manner. These miRNAs singly or jointly displayed an improved diagnostic capability to differentiate serological cure patients or healthy people from serofast syphilis. Conclusions: In practical work, differently-expressed exosomal miRNAs may be of great clinical significant utility in the diagnosis and prognosis of serofast syphilis. According to the data, miR-197-3p, miR- 1908-3p, miR-1273g-3p, miR-4485-5p within exosomes might singly or jointly be potential diagnostic biomarkers at serofast syphilis.