<i>Pentatrichomonas hominis</i> Infection Induces Chronic Intestinal Inflammation in Immunocompetent Mice

<i>Pentatrichomonas hominis</i> (<i>P. hominis</i>) has traditionally been regarded as a commensal or opportunistic inhabitant of the intestine. However, a growing number of studies have identified this protozoan as the sole pathogen in cases of intestinal disorders, including diarrhea, in both humans and animals, suggesting it may be a neglected zoonotic pathogen. To investigate the pathogenicity of <i>P. hominis</i>, we here systematically evaluated its effects on healthy immunocompetent BALB/c mice. Our findings revealed that infection with <i>P. hominis</i> induced injury in the large intestine, marked by inflammatory cell infiltration, epithelial cell necrosis, and intestinal mucosal sloughing. These pathological changes persisted and worsened throughout the 90-day observation period. Furthermore, infection appeared to disrupt goblet cell maturation or secretion, as indicated by increased periodic acid-Schiff (PAS) staining alongside decreased MUC2 production. Elevated levels of pro-inflammatory cytokines were also detected in both intestinal lavage fluid and serum. Finally, <i>P. hominis</i> infection altered the composition of the gut microbiota, increasing both its richness and diversity. Notably, it raised the relative abundance of the inflammation-associated genus <i>Desulfovibrio</i>, while reducing the abundance of beneficial bacteria, such as <i>Akkermansia</i>, <i>Roseburia</i>, and <i>Lactobacillus</i>. Collectively, these results provide compelling evidence that <i>P. hominis</i> acts as a zoonotic pathogen capable of inducing chronic intestinal inflammation. Therefore, the clinical significance of <i>P. hominis</i> infection warrants attention.