Tritrichomonas murissensitizes the intestinal epithelium to doxorubicin-induced apoptosis

Abstract

ABSTRACTDoxorubicin (DXR) is a widely used chemotherapy drug that can induce severe intestinal mucositis. While the influence of gut bacteria on DXR-induced damage has been documented, the role of eukaryotic commensals remains unexplored. We discoveredTritrichomonas muris(Tmu) in one of our mouse colonies exhibiting abnormal tuft cell hyperplasia, prompting an investigation into its impact on DXR-induced intestinal injury. Mice fromTmu-colonized andTmu-excluded facilities were injected with DXR, and tissue morphology and gene expression were evaluated at acute injury (6 h) and peak regeneration (120 h) phases. Contrary to previous reports, DXR did not significantly alter villus height, crypt depth, or crypt density in any mice. However, we did observe apoptosis, measured by cleaved caspase 3 (CC3) staining, in intestinal crypts at 6 h post-DXR that was significantly higher in mice colonized byTmu. Interestingly, while DXR did not alter the expression of active and facultative intestinal stem cell (ISC) marker genes in control mice, it significantly reduced their expression inTmu+mice.Tmu, but not DXR, is also associated with increased inflammation and expression of the type 2 cytokines IL-5 and IL-13. However, pre-treatment of intestinal organoids with these cytokines is not sufficient to drive elevated DXR-induced apoptosis. These findings highlight the significant influence of commensal microbiota, particularly eukaryotic organisms likeTmu, on intestinal biology and response to chemotherapy, underscoring the complexity of gut microbiota interactions in drug-induced mucositis.NEW & NOTEWORTHYOur study found that the eukaryotic commensalTritrichomonas muris(Tmu) significantly increases DXR-induced intestinal apoptosis in mice, despite no changes in tissue morphology.Tmualso reduces intestinal stem cell gene expression post-DXR injury, and elevates inflammation and type 2 cytokine expression in the absence of injury.In vitroorganoid assays suggest that type 2 cytokines alone are insufficient to promote increased DXR-associated apoptosis. These findings emphasize the complex role of gut microbiota in drug-induced intestinal damage.