The Impact of Vaginal Bacteria on Vaginal Fibroblasts from Women with Pelvic Organ Prolapse

Objectives: The effect of reproductive tract microbiome on the vagina is a dynamic and evolving area of investigation. Bacterial vaginosis (BV), a condition characterized by an overgrowth of anaerobic bacteria in the vagina, is associated with an increased risk of surgical site infection following pelvic surgery. BV-associated microbes have been shown to impair epithelial repair, yet data is lacking on how they impact fibroblast cells, the main cell type of connective tissue. Altered cellular functionality, especially in the presence of distinct bacterial communities, may influence tissue quality and capability for wound healing. The objective of this study was to investigate the impact of the BV-associated microbes on vaginal fibroblast proliferation.

Methods: Vaginal wall tissue from women undergoing pelvic organ prolapse (POP) surgery was digested and cultured to obtain primary fibroblasts. Lactobacillus crispatus, Lactobacillus iners, and two strains of Gardnerella vaginalis (strains GR34 and ATCC 14018) were cultured in NYC III broth to stationary phase, and the culture filtered to generate a cell-free supernatant. Human vaginal fibroblasts were then co-cultured in (1) cell culture media alone, (2) cell culture media with 1nM estradiol, (3) cell culture media with 5% bacterial cell-free supernatants. LDH Cytotoxicity Assay was used to assess cell death at three time points: 0, 24, and 48 hours of exposure.

Results: Primary vaginal fibroblasts were isolated from 9 women (2 premenopausal, 7 postmenopausal) undergoing POP surgery. The median age and BMI were 58.5 and 30, respectively. 78% of participants were postmenopausal and 78% of participants were not on vaginal estrogen therapy at the time of surgery (Table 1). There was significantly greater cell death when vaginal fibroblasts were exposed to G. vaginalis supernatants compared to cell culture media alone at 24 hours (strain GR 34 57%, strain ATCC 14018 56% vs. 10% control, p< 0.001). There was no significant difference when cells were exposed to L. crispatus (p =0.70), L. iners (p =0.81), and estradiol media (p=0.19) (Figure 1).

Conclusions: Exposure to G. vaginalis supernatants led to death of primary vaginal fibroblasts. This suggests that BV-associated microbes may impact the health of vaginal fibroblasts, the major cell type that promotes tissue remodeling and wound healing. Further studies are needed to elucidate the mechanism by which G. vaginalis alters cellular function.