Could a pathogen and dysbiotic bacteria help dispersion of each other?

Abstract

The human vaginal microbiome is a complex ecosystem primarily governed by lactobacilli, which create an acidic environment and defend against pathogens. However, when lactobacilli decrease, anaerobic bacteria such as, Gardnerella vaginalis among others may flourish as a polymicrobial condition known as bacterial vaginosis (BV). Coincidently, the vaginal infection by the protozoan Trichomonas vaginalis (i.e., trichomoniasis) is accompanied by this dysbiotic BV-like microbiome. Therefore, the interactions between G. vaginalis and T. vaginalis, despite poorly understood, might be crucial for the disease development. In BV, G. vaginalis is the initiator of a pathogenic vaginal biofilm. With this knowledge, this study aimed to understand how these two microorganisms may help disperse each other. To address this gap of knowledge, this research employed complementary approaches to evaluate biofilm growth and dispersion, and the adhesion of T. vaginalis to this biofilm. This research also considered the involvement of secreted T. vaginalis DNases in these processes. Finally, this research examined whether extracellular vesicles (EVs) produced by lactobacilli and G. vaginalis would influence the dispersion of T. vaginalis on agar-based assays. This research demonstrated that T. vaginalis avidly adheres to the G. vaginalis biofilm and enhances bacterial dispersion. The participation of secreted DNases of T. vaginalis in these processes was hindered by unforeseen endogenous cleavage of these enzymes, thus further research is required to examine this. Bacterial EVs were shown to affect T. vaginalis dispersion, however, that optimisation of techniques in here or new ones should be used to characterise this process in depth. Studying these intricate microbial relationships and their underlying mechanisms holds promise for advancing our understanding of BV and trichomoniasis. Unravelling these interactions could lead to novel therapeutic strategies targeting the dysbiotic vaginal microbiome, ultimately restoring a healthy environment and improving female reproductive health.