Abstract
Background: The comparison between microbiota of cecal and colonic mucosa in irritable bowel syndrome (IBS) was rarely studied. In addition, enterochromaffin (EC) cell had interaction with IBS. The aim of this study was to investigate the relationship among gut microbiota, EC cell and diarrhea-predominant IBS (IBS-D) symptoms in cecum and descending colon. Methods: Biopsies from cecum and descending colon were taken during endoscopy withdrawal. We assessed EC cell numbers, expression of tryptophan hydroxylase 1 (TPH1) and microbial diversity.Results: Total of 22 IBS-D patients and 22 health controls (HCs) were enrolled. The relative abundance of Ruminococcus_torques_group (4.91% vs. 2.20%, P = 0.04763) of cecum increased in IBS-D, while Raoultella (1.58% vs. 1.76%, P = 0.03117) and Fusobacterium (0.12% vs. 1.66%, P = 0.01892) were less abundant. In descending colon, the relative abundances of Ruminococcus_torques_group (5.94% vs. 2.29%, P = 0.04183) and Dorea (2.68% vs. 1.14%, P = 0.04962) of IBS-D increased but Fusobacterium (1.52% vs. 1.89%, P = 0.0345) decreased. EC cells number in cecum of IBS-D was higher than that in HCs and TPH1 level of IBS-D was higher than that of HCs in cecum and descending colon. Correlation analysis showed that Ruminococcus_torques_group were positively associated with HAM-A (r= 0.66, P = 0.004), HAM-D (r= 0.61, P = 0.009), EC cell number (r= 0.49, P = 0.047), IBS-SSS (r= 0.65, P = 0.004), Degree of Abdominal Pain (r = 0.63, P = 0.007), Frequency of Abdominal Pain (r = 0.63, P = 0.007), Frequency of Defecation (r = 0.60, P = 0.011). The abundance of Dorea were positively associated with EC cell number (r = 0.57, P = 0.018), IBS-SSS (r = 0.52, P = 0.034), HAM-A (r = 0.72, P = 0.001), HAM-D (r = 0.59, P = 0.012), Frequency of Abdominal Pain (r = 0.67, P = 0.003).Conclusions: EC cells number increased in IBS-D patients and the expression of TPH1 was higher than HCs. In addition, our results suggested Ruminococcus_torques_group and Dorea may be targets for treatment of IBS-D but still need further studies.