Dynamics of Fecal microRNAs Following Fecal Microbiota Transplantation in Alcohol-Related Cirrhosis.

Background: Micro-RNAs (miRNAs) are emerging as pivotal regulators of pathophysiological processes, reflecting systemic responses to stress, inflammation and metabolic imbalance. Their role in advanced liver disease and in modulating responses to therapeutic interventions, such as fecal microbiota transfer (FMT), remains insufficiently characterized. Methods: We conducted a prospective study including six male patients with toxic ethanolic liver cirrhosis undergoing FMT and six healthy controls. Stool and blood samples were collected pre- and post-FMT. Fecal micro-RNA expression (miR-21, miR-122, miR-125, miR-146 and miR-155) was quantified using RT-qPCR and normalized to miR-26c. Associations with noninvasive fibrosis markers (FIB-4, APRI, elastography, CAP) and biological parameters were analyzed through multivariable regression and Pearson correlation, with internal validation by bootstrapping. Results: One week after fecal microbiota transfer, miR-21 and miR-146 exhibited significant expression changes, while miR-122, miR-125, and miR-155 showed non-significant trends toward increased expression. Post-FMT increases in miR-21, miR-122, miR-146 and miR-155 were consistently associated with reductions in hepatic fibrosis markers (FIB-4, APRI and liver stiffness), whereas no significant associations were observed with CAP. Conclusions: Fecal micro-RNAs reflect interconnected molecular networks that capture systemic adaptations to FMT. Despite a limited cohort, these findings highlight their potential as integrative biomarkers and as therapeutic targets in advanced liver disease. Larger-scale studies are warranted to validate clinical utility.