Multi-omics profiling and bile-acid exposure assays implicate a gut microbiome-parasite axis linked to persistent...

Asymptomatic Entamoeba histolytica (Eh) carriage is a major transmission reservoir, yet how the gut ecosystem-particularly microbiota-derived metabolites such as secondary bile acids-supports persistent colonization remains unclear. We investigated whether gut microbiome-metabolite features are associated with Eh carriage and could influence parasite phenotypes METHODS: We integrated shotgun metagenomics from a prospectively screened outpatient cohort (n=36) with functional in vitro assays. An ordinal stepwise model across detection states (Eh-, Eh_qPCR, Eh_Cyst) was used to identify candidate microbial features, followed by bile-acid exposure assays and transcriptomic profiling to evaluate impacts on parasite fitness and metronidazole susceptibility in vitro RESULTS: Microbiome profiling suggested taxon-specific shifts rather than wholesale dysbiosis. Community-level beta diversity showed no significant separation, whereas genus richness was higher in Eh_Cyst (unadjusted p=0.046). Multivariable modeling yielded concordant directional but non-significant trends (all q>0.9), highlighting Firmicutes genera including Coprococcus, Ruminococcus, and Catenibacterium as candidate taxa. We then evaluated deoxycholic acid (DCA), a microbiota-modified secondary bile acid. In vitro, 100 μM DCA extended Eh survival under nutrient-limited conditions and reduced metronidazole susceptibility after pretreatment. Transcriptomic profiling showed that DCA induced a distinct response, including an 8.34-fold induction of the ABC transporter P-glycoprotein-2 and upregulation of lipid remodeling and stress-response genes, supporting a bile acid-driven adaptive program consistent with intestinal persistence CONCLUSIONS: Our findings suggest that secondary bile acids, exemplified by DCA, can reprogram Eh gene expression and attenuate metronidazole susceptibility in vitro. In the context of cyst-associated microbiome signatures, this supports the plausibility of a microbiome-bile acid-parasite axis that may promote persistence in asymptomatic carriers and could influence treatment efficacy.