P1219 Changes in gut microbiota of patients with inflammatory bowel disease receiving biologic therapy

Inflammatory bowel disease (IBD), comprising the predominant forms Crohn’s disease (CD) and ulcerative colitis (UC), is associated with compositional and metabolic changes in the intestinal dysbiosis. The aim of this study is to evaluate the composition in the microbiota of IBD patients who received biologic therapy This is a prospective study recruited 14 patients with IBD received biologic therapy and 13 IBD controls who received conventional treatment . The taxonomic composition of the gut microbiota was determined by 16S ribosomal RNA gene sequencing of stool samples. The stool samples at baseline, weeks 6 and 48 after biologic therapy initiation were assessed. We also evaluated the level of inflammation and treatment response of biologics by BD activity score (CD patient by Crohn’s disease activity index [CDAI] and in UC patient by Mayo score). In CD group, we recruited 7 CD patients receiving biologic therapy (Anti-tumor Necrosis Factor for 4 and anti-integrin for 3) and 6 controls.In UC group, we recruited 7 UC patient receiving biological therapy (Anti-tumor Necrosis Factor for 2 and anti-integrin for 5) and 7 controls. Community α-diversity was lower in patients at baseline of biologics group compare to controls significantly but increase abundance and richness after achieving remission in trend at week 6 and week 48, respectively. In Top 10 taxon bacterial distribution, the Firmicutes were increase its abundances gradually ( relative abundance in biologics W0,W6,W48 and controls were 46.3%, 51.7%,62.0%, and 66.4%, respectively). Conversely, the Bacteroidetes were decrease its abundances ( relative abundance in biologics W0,W6,W48 and controls were18.3%, 18.8%, 10.2% and 6.4%, respectively). Increased F/B ratio significantly after biologics therapy also found in our study. (F/B ratio were 9.4, 12.5,64.0,and 84.3,respectively). Patients in control group had higher abundance of Firmicutes of the phylum.By contrast, Enterobacteriaceae and Bacteroidaceae were significantly more abundant in patients of biologics group at W0 . Treatment with biologic therapy induced improvement of community diversity and increased F/B ratio in IBD patients which seemed correlate the level of clinical inflammation. The dysbiosis-representative bacteria, such as Enterobacteriaceae, could induce colonic inflammation,were more abundant in patients who had higher activity of IBD. Further larger prospective studies are needed to determine whether the biologic therapy could induce long-term changes of intestinal microbiome.