The gut microbiome predicts response to UDCA/CDCA treatment in gallstone patients: comparison of responders and non-responders

The treatment of gallbladder (GB) stones depends on condition severity. Ursodeoxycholic acid (UDCA) and chenodeoxycholic acid (CDCA) are commonly used to treat GB stones, but the factors affecting response rates have not been fully identified. Therefore, we investigated the relationship between response to UDCA/CDCA treatment and changes in the gut microbiomes of patients with GB stones with the intention of identifying gut microbiomes that predict susceptibility to UDCA/CDCA treatment and treatment response. In this preliminary, prospective study, 13 patients with GB stones were treated with UDCA/CDCA for 6 months. Patients were classified into responder and non-responder groups based on treatment outcomes. Gut microbiomes were analyzed by 16S rDNA sequencing. Taxonomic compositions and abundances of bacterial communities were analyzed before and after UDCA/CDCA treatment. Alpha and beta diversities were used to assess similarities between organismal compositions. In addition, PICRUSt2 analysis was conducted to identify gut microbial functional pathways. Thirteen patients completed the treatment; 8 (62%) were assigned to the responder group and the remainder to the non-responder group. Low abundances of the Erysipelotrichi lineage were significantly associated with favorable response to UDCA/CDCA treatment, whereas high abundances of Firmicutes phylum indicated no or poor response. Our results suggest that a low abundance of the Erysipelotrichi lineage is significantly associated with a favorable response to UDCA/CDCA and that a high abundance of Firmicutes phylum is indicative of no or poor response. These findings suggest that some gut microbiomes are susceptible to UDCA/CDCA treatment and could be used to predict treatment response in patients with GB stones.