Tritrichomonas spp. and Their Impact on Gut Immune Homeostasis

The intestinal microbiota, the collection of all microorganisms residing in our gastrointestinal tract, provides a plethora of microbial diversity. Bacteria, viruses, fungi, worms and protozoa are the primary microorganisms comprising our microbiota. These microbes include representative species capable of both causing severe harm or symbiotic benefits to their host. In relation, the host immune system has evolved complex detection systems to identify members of each microbial faction and interpret their harmful or peaceful capabilities. As a consequence, our immune system mounts appropriate responses to either eliminate or tolerate members of our microbiota. Protozoa are an underappreciated kingdom within our microbiota and the interactions of these microbes with our immune system remain understudied. Several recent reports have demonstrated that the presence of Tritrichomonas spp. in the intestinal tract of mice and men facilitates novel interactions with our host immune system. Within this chapter, we are summarizing the most recent knowledge on how Tritrichomonads, as a newly emerging group of intestinal protozoan commensals, shape and communicate with our intestinal immune system.