Pentatrichomonas hominis Infection Induces Chronic Intestinal Inflammation in Immunocompetent Mice.

Pentatrichomonas hominis (P. hominis) 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 P. hominis, we here systematically evaluated its effects on healthy immunocompetent BALB/c mice. Our findings revealed that infection with P. hominis 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, P. hominis 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 Desulfovibrio, while reducing the abundance of beneficial bacteria, such as Akkermansia, Roseburia, and Lactobacillus. Collectively, these results provide compelling evidence that P. hominis acts as a zoonotic pathogen capable of inducing chronic intestinal inflammation. Therefore, the clinical significance of P. hominis infection warrants attention.