Approximately 80% of patients with Primary Sclerosing Cholangitis (PSC) also have an underlying Inflammatory Bowel Disease (IBD). Notably, PSC-IBD presents a unique phenotype compared to Ulcerative Colitis or Crohn’s Disease alone , which may increase the risk of colitis-associated neoplasia. This case-control study comprises a cohort of 15 patients in the PSC-IBD group, 30 patients in the IBD-alone group, and 19 patients in the control group. Through the analysis of patient serum and colon tissue proteomics, colon gene expression, fecal gut microbiota, and in vitro data with human monocytes, we identified a specific interplay between systemic circulation and gut microbiota dysbiosis that may predispose PSC-IBD patients to neoplasia development. Our study revealed that PSC-IBD patients show a shift in gut microbiota towards an increase in Intestinibacter, a bacterium known to exacerbate IBD conditions.Interestingly, when comparing the PSC-IBD group to the IBD-alone group, we observed elevated miR-21 expression levels in fasting serum and stool samples. Finally, we partially reproduce the inflammatory PSC-IBD profile using miR-21 and bile acid GCDCA stimulus in human-derived monocytes. Our findings suggest that circulating miR-21, along with bile acid GCDCA, tissue macrophage recruitment, and distinct microbiota profiles, may contribute to the unique phenotype of IBD in PSC patients.