Trichomonas vaginalisInduces NLRP3 Inflammasome Activation and Pyroptotic Cell Death in Human Macrophages

Trichomonas vaginalisis a sexually transmitted, eukaryotic parasite that causes trichomoniasis, the most common nonviral, sexually transmitted disease in the USA and worldwide. Little is known about the molecular mechanisms involved in the host immune response to this widespread parasite. Here we report that T. vaginalisinduces NLRP3 inflammasome activation in human macrophages, leading to caspase-1 activation and the processing of pro-IL-1β to the mature and bioactive form of the cytokine. Using inhibitor-based approaches, we show that NLRP3 activation by T. vaginalisinvolves host cell detection of extracellular ATP via P2X7receptors and potassium efflux. In addition, our data reveal that T. vaginalisinflammasome activation induces macrophage inflammatory cell death by pyroptosis, known to occur via caspase-1 cleavage of the gasdermin D protein, which assembles to form pores in the host cell membrane. We found that T. vaginalis-induced cytolysis of macrophages is attenuated in gasdermin D knockout cells. Lastly, in a murine challenge model, we detected IL-1β production in vaginal fluids in response to T. vaginalisinfection in vivo. Together, our findings mechanistically dissect how T. vaginaliscontributes to the production of the proinflammatory IL-1β cytokine and uncover pyroptosis as a mechanism by which the parasite can trigger host macrophage cell death.