Inflammatory responses during trichomoniasis: The role of Toll-like receptors and inflammasomes.

Toll-like receptors (TLRs) and inflammasomes belong to the pattern recognition receptors (PRRs) of innate immunity identifying conserved compounds produced by pathogens or discharged by injured cells. Different cell subsets in the human urogenital system, such as epithelial cells and infiltrating leukocytes, express different kinds of TLRs (such as TLR2, TLR3, TLR4, TLR5 and TLR9) as well as inflammasomes (such as NLRP3, NLRC4 and AIM2). Various types of the Trichomonas vaginalis-derived components such as glycosyl-phosphatidylinositol (GPI), T. vaginalis virus (TVV), Lipophosphoglycan (LPG) and flagellin can be recognized by TLR2, TLR3, TLR4 and TLR5, respectively, leading to the production of proinflammatory cytokines and chemokines in the cervicovaginal mucosa. The T. vaginalis-induced inflammasomes can lead to pyroptosis as well as the release of IL-1β and IL-18 promoting innate and adaptive immune responses. The PRR-mediated responses to T. vaginalis may contribute to the induction of protective immune responses, local inflammation, promotion of co-infections, or even the development of malignancies, for example, prostate cancer. The protective or pathogenic roles of the TLRs and inflammasomes during trichomoniasis are highlighted in this review. A better understanding of PRR-mediated responses provides invaluable insights to develop effective immunotherapeutic strategies against T. vaginalis infection.