Differential miRNA Profiles Correlate With Disparate Immunity Outcomes Associated With Vaccine Immunization and Chlamydial Infection

Vaccine-induced immune responses following immunization with promising Chlamydia vaccines protected experimental animals from Chlamydia-induced upper genital tract pathologies and infertility. In contrast, primary genital infection with live Chlamydia does not protect against these pathologies. We hypothesized that differential miRNA profiles induced in the upper genital tracts (UGT) of mice correlate with the disparate immunity vs. pathologic outcomes associated with vaccine immunization and chlamydial infection. Thus, miRNA expression profiles in the UGT of mice after Chlamydia infection (Live EB) and immunization with dendritic cell (DC)-based vaccine (DC vaccine) or VCG-based vaccine (VCG vaccine) were compared using the NanoString nCounter Mouse miRNA assay. Of the 602 miRNAs differentially expressed (DE) in the UGT of immunized and infected mice, we selected 58 with counts >100 and p-values < 0.05 for further analysis. Interestingly, vaccine immunization and Chlamydia infection induced the expression of distinct miRNA profiles with a higher proportion in vaccine-immunized compared to Chlamydia infected mice; DC vaccine (41), VCG vaccine (23), and Live EB (15). Hierarchical clustering analysis showed notable differences in the uniquely DE miRNAs for each experimental group, with DC vaccine showing the highest number (21 up-regulated, five down-regulated), VCG vaccine (two up-regulated, five down-regulated), and live EB (two up-regulated, four down-regulated). The DC vaccine-immunized group showed the highest number (21 up-regulated and five down-regulated compared to two up-regulated and four down-regulated in the live Chlamydia infected group). Pathway analysis showed that the DE miRNAs target genes that regulate several biological processes and functions associated with immune response and inflammation. These results suggest that the induction of differential miRNA expression plays a significant role in the disparate immunity outcomes associated with Chlamydia infection and vaccination.

The differential pathological outcome between Chlamydia infection and vaccination is mediated by microRNA dysregulation

Previous studies found that in contrast to immunization with an IL-10 knockout dendritic cell (DC)-based cellular or Vibrio cholerae ghost (VCG)-based subunit vaccine, immunization with live chlamydial elementary bodies does not protect against upper genital tract pathology following Chlamydia genital infection. The molecular mechanism regulating live Chlamydia- and vaccine-induced immunity is currently incompletely understood. To elucidate the mechanisms underlying this intriguing outcome, we examined the characteristic miRNA expression profiles in the upper genital tract (UGT) tissues of mice after immunization with live, subunit and DC-based Chlamydia vaccines using the NanoString nCounter Mouse miRNA assay. There were notable differences in miRNA expression profiles after immunization with the different vaccine formulations, with the DC vaccine-immunized group showing the highest number of uniquely differentially expressed (DE) miRNAs. Only 2 miRNAs, miR-146a and miR-2140 were commonly expressed in the genital tracts of the 3 immunization groups. Pathway analysis showed that the DE miRNAs regulate a number of pathways involved in disease and biological functions and targeted genes regulating immune response and inflammation. A number of central focus molecules associated with the miRNAs, including E2F Transcription Factor 1 (E2F1), Peroxisome Proliferator Activated Receptor Alpha (PPARA), and Interferon gamma (IFNG) were identified. Taken together, the results suggest that miRNA dysregulation plays an important role in the pathological outcome associated with chlamydial infection versus vaccination.

Dysregulation in Genital Tract Soluble Immune Mediators in Postmenopausal Women Is Distinct by HIV Status

A rise in new HIV diagnoses among older adults is characterized by poor prognosis and reduced survival times. Although heterosexual transmission remains the main route of infection in women, little is known regarding immune functions in the genital tract of postmenopausal women, especially those who are HIV positive. Furthermore, effects of hormone replacement therapy (HRT) on the genital tract immune system are unclear. Using the Women's Interagency HIV Study repository, we obtained cervical-vaginal lavage (CVL) samples from premenopausal and postmenopausal HIV-positive and HIV-negative women, some of whom were on HRT. Samples were assayed for interleukin (IL)-6, IL-8, tumor necrosis factor (TNF)-α, secretory leukocyte protease inhibitor (SLPI), Elafin, human beta defensin-2 (HBD2), and macrophage inflammatory protein (MIP)-3α using ELISA. Anti-HIV activity in CVL was measured using TZM-bl indicator cells. Among HIV-positive women, the plasma viral load was significantly higher and CD4 count was significantly lower in postmenopausal compared with premenopausal women. Postmenopausal women, irrespective of HIV status, had significantly lower levels of HBD2 compared with premenopausal women. Among the HIV-negative individuals, postmenopausal women had significantly lower levels of MIP-3α, IL-6, and SLPI compared with premenopausal women. In contrast, HIV-positive postmenopausal women had significantly higher levels of TNF-α compared with HIV-positive premenopausal women. In most cases, HRT groups resembled the postmenopausal groups. No significant differences in anti-HIV activity by menopausal or by HIV status were noted. Our findings indicate that the female genital tract immune microenvironment is distinct by menopausal status and HIV status. Further studies are needed to assess the risk of HIV acquisition/transmission in this population.

A unique insight into the MiRNA profile during genital chlamydial infection

Background

Genital C. trachomatis infection may cause pelvic inflammatory disease (PID) that can lead to tubal factor infertility (TFI). Understanding the pathogenesis of chlamydial complications including the pathophysiological processes within the female host genital tract is important in preventing adverse pathology. MicroRNAs regulate several pathophysiological processes of infectious and non-infectious etiologies. In this study, we tested the hypothesis that the miRNA profile of single and repeat genital chlamydial infections will be different and that these differences will be time dependent. Thus, we analyzed and compared differentially expressed mice genital tract miRNAs after single and repeat chlamydia infections using a C. muridarum mouse model. Mice were sacrificed and their genital tract tissues were collected at 1, 2, 4, and 8 weeks after a single and repeat chlamydia infections. Histopathology, and miRNA sequencing were performed.

Results

Histopathology presentation showed that the oviduct and uterus of reinfected mice were more inflamed, distended and dilated compared to mice infected once. The miRNAs expression profile was different in the reproductive tissues after a reinfection, with a greater number of miRNAs expressed after reinfection. Also, the number of miRNAs expressed each week after chlamydia infection and reinfection varied, with weeks eight and one having the highest number of differentially expressed miRNAs for chlamydia infection and reinfection respectively. Ten miRNAs; mmu-miR-378b, mmu-miR-204-5p, mmu-miR-151-5p, mmu-miR-142-3p, mmu-miR-128-3p, mmu-miR-335-3p, mmu-miR-195a-3p, mmu-miR-142-5p, mmu-miR-106a-5p and mmu-miR-92a-3p were common in both primary chlamydia infection and reinfection. Pathway analysis showed that, amongst other functions, the differentially regulated miRNAs control pathways involved in cellular and tissue development, disease conditions and toxicity.

Conclusions

This study provides insights into the changes in miRNA expression over time after chlamydia infection and reinfection, as well as the pathways they regulate to determine pathological outcomes. The miRNAs networks generated in our study shows that there are differences in the focus molecules involved in significant biological functions in chlamydia infection and reinfection, implying that chlamydial pathogenesis occurs differently for each type of infection and that this could be important when determining treatments regime and disease outcome. The study underscores the crucial role of host factors in chlamydia pathogenesis.

Electronic supplementary material

The online version of this article (10.1186/s12864-019-5495-6) contains supplementary material, which is available to authorized users.