Abstract

Background: Fecal microbiota transplantation (FMT) may contribute to disease remission in ulcerative colitis (UC). We studied the microbiota change and its regulation on T cells after FMT. Methods: Patients with mild to moderately active UC were included to receive FMT. The intestinal histopathological changes and barrier function were evaluated. The fecal samples of donors and patients were analyzed by 16S rRNA gene-based microbiota analysis, and the colon Th17 and Treg cells were assessed. Results: Fifteen patients completed the 8-week-follow-up. A total of 10 patients (66.7%) were in the responders (RE) group and five in the non-responders (NR) group. The Nancy histological index and fecal calprotectin decreased (p< 0.001,p= 0.06, respectively) and Occludin and Claudin1 increased in the RE group. The abundance ofFaecalibateriumincreased significantly by 2.3-fold in the RE group at week 8 (p= 0.043), but it was suppressed in the NR group. Fecal calprotectin (r = −0.382,p= 0.003) and Nancy index (r = −0.497,p= 0.006) were correlated inversely with the abundance ofFaecalibacterium, respectively. In the RE group the relative mRNA expression of RORγt decreased and Foxp3 increased. Significantly decreased CD4+ RORγt+ Th17 and increased CD4+ Foxp3+ Treg were also observed in the RE group. The relative abundance ofFaecalibacteriumcorrelated with CD4+ RORγt+ Th17 (r = −0.430,p= 0.018) and CD4+ Foxp3+ Treg (r = 0.571,p= 0.001). Conclusions: The long-termFaecalibateriumcolonization following FMT plays a crucial role in UC remission by alleviating intestinal inflammation. This anti-inflammatory effect ofFaecalibacteriummay be achieved by regulating the imbalance of Th17/Treg levels in UC.Keywords:ulcerative colitis;fecal microbiota transplantation;T cell