MicroRNA expression profiling of peripheral blood mononuclear cells associated with syphilis

Treponema pallidum (Tp) infection evokes vigorous immune responses, resulting in tissue damage. The immune mechanism after Treponema pallidum infection is still not clear. MicroRNAs (miRNAs) have been shown, however, to influence immune cell function and consequently the generation of antibody responses during other microbe infections, but these values are unknown for Tp. In this study, we performed a comprehensive analysis of differentially expressed miRNAs in healthy persons, untreated patients with syphilis, patients in the serofast state, and serologically cured patients. MiRNAs were profiled from patient peripheral blood obtained at the time of serological diagnosis. There were 89 differentially regulated miRNA identified in total. Then both the target sequence analysis on these different miRNAs and pathway analysis were performed to identify important immune and cell signaling pathways. Following RT-qPCR confirmation, three miRNAs (hsa-miR-195-5p, hsa-miR-223-3p, hsa-miR-589-3p) showed significant difference among serofast state, and serological cure (P<0.05). Two miRNAs (hsa-miR-195-5p, hsa-miR-1204) showed significant differences among untreated patients and healthy individuals. This is the first study of miRNA expression difference in PBMC in different stages of T. pallium infection. Our study suggests that the combination of three miRNAs has great potential to serve as non-invasive biomarkers of Treponema pallidum infections, which will facilitate better diagnosis and treat of T. pallium infections. This study examined 4 groups of healthy controls, syphilitic patients, serofast state and serologically cured patients. There are 6 samples per group. Sample A1-A6 mean healthy controls, B1-B6 mean serofast state, C1-C6 mean syphilitic patients, D1-D6 mean serologically cured patients.