Biocompatibility of a Novel Prebiotic Vaginal Gel for Treating the Underlying Conditions of Vaginal Dysbiosis and Inflammation That Facilitate Cervical Cancer Formation and Progression

PURPOSE PreBioGyn (a user-directed, intravaginal prebiotic gel) aims to reduce the risk of cervical cancer formation and progression associated with vaginal dysbiosis and inflammation. Studies were done to compare in vitro biocompatibility for PreBioGyn versus available vaginal pH-correcting buffer-gels (RepHresh and Trimosan) with regards to vaginal epithelial cell integrity, beneficial lactobacilli colonization, and cytokine production. METHODS Gel biocompatibility was tested with two beneficial Lactobacillus species (L. crispatus and L. jensenii) in a validated 3D human vaginal epithelial model (VEC). Gels mixed with bacterial suspensions were applied to the model for 24h. Bacterial colonization was assessed by colony forming units (CFU) firmly associated with the VEC. Bacterial-gel suspensions at time 0 and tissue lysates at the 24h-time point were seeded on Brucella agar and colonies were counted after 2-4 days. Tissue toxicity was assessed by lactate dehydrogenase release with positive (Triton X-100) and negative (medium only) controls. Medium from the submucosal tissue compartment was analyzed after 24h colonization for: 1) IL-1α, IL-1β and IL-1RA as markers of toxicity and inflammatory activation, and 2) IL-8 as innate immunity effector of inflammation. The VEC tissues were also cocultured with HeLa cells to mimic cervical cancer environments. ANOVA with multiple comparisons tests was performed on biological duplicates from at least 3 experiments for each condition with significance at P< 0.05. RESULTS PreBioGyn demonstrated no VEC toxicity, whereas currently available buffer-gels caused epithelial cytotoxicity. PreBioGyn did not change beneficial lactobacillus survival and growth prior to or during epithelial coculture. In contrast, Trimosan was bactericidal and both Trimosan and RepHresh reduced lactobacillus colonization. None of the gels increased extracellular IL-1α and IL-1β levels, while PreBioGyn reduced IL-8 levels in the presence of HeLa cells without harming VEC, suggesting anti-inflammatory properties. CONCLUSION Overall, impaired vaginal immune barrier function was suggested with the currently available pH-buffer gels due to toxicity to VEC and beneficial lactobacilli. In contrast, the prebiotic PreBioGyn gel supported the vaginal ecosystem function similarly to that observed with homeostatic media co-culture, lending support to this approach for preventing dysbiosis and inflammation to facilitate reduced cervical cancer risk.