BACTEROIDETES SPECIES ARE USEFUL BIOMARKER OF CLINICAL ACTIVITY IN ULCERATIVE COLITIS

Abstract Background We previously reported that there were 13 species of Bacteroidetes phylum with significantly higher or lower relative abundance in patients with ulcerative colitis (UC) than healthy individuals. In this study, we investigated the correlation between Bacteroidetes species components in fecal samples and clinical evaluations of UC. Method This study included participants above 20 years of age. Fecal samples were collected for microbial analysis from 54 patients who had active UC based on a Lichtiger’s clinical activity index (CAI) ≥ 4 or an endoscopic Mayo clinic score ≥1. DNA was extracted from the fecal samples and analyzed by next-generation sequencing (the Illumina MiSeq sequencing system) targeting hsp60. We verified associations between Bacteroidetes species and eMayo sum score (total of endoscopic Mayo clinic scores in each intestine: periphery of appendix vermiformis, cecum, ascending colon, transverse colon, descending colon, sigmoid colon, and rectum), Robarts Histopathology Index (RHI), and CAI. Results Bacteroides uniformis (R = -0.44, p = 0.002) and four others significantly correlated with eMayo sum score. Alistipes shahii (R = -0.35, p = 0.02) and three others significantly correlated with RHI. Bacteroides rodentium (R = -0.37, p = 0.006) and two others significantly correlated with CAI. Furthermore, three Bacteroidetes species (Bacteroides stercoris, Bacteroides uniformis, and Parabacteroides merdae) correlated with two of three clinical evaluations, and the total relative abundance of these three species showed stronger correlation with eMayo sum score (R = -0.52, p = 0.00007). Conclusion All eight Bacteroidetes species identified in this study represented negative correlation with the clinical activity, so these species are suggested to be lost by exacerbation. Bacteroidetes species, especially total relative abundance of three Bacteroidetes species (Bacteroides stercoris, Bacteroides uniformis, and Parabacteroides merdae) may become a biomarker for evaluating the clinical activity of UC.