Associations of sigmoid colon mucosal mast cells with bowel symptoms and psychological status in patients with irritable bowel syndrome with diarrhea

Abstract

To investigate the bowel symptoms and psychological status of patients with irritable bowel syndrome (IBS) with diarrhea (IBS-D), and to verify whether sigmoid colon mucosal mast cells (MCs) and their activation have effect on the symptoms and psychological status of IBS-D patients. Patients meeting Rome Ⅲ diagnostic and subtyping criteria of IBS-D who visited the outpatient clinic of gastroenterology of Peking Union Medical College Hospital were consecutively enrolled between July 2009 and June 2012. IBS symptoms questionnaire was completed using face-to-face interview, and Hamilton Anxiety Scale (HAMA)/ Hamilton Depression Scale (HAMD) were administrated to evaluate psychological status, both by well-trained investigators. Mast cell tryptase monoclonal antibody was used for immunohistochemical staining to detect MCs and degranulated MCs in mucosal biopsy of sigmoid colon. MCs and degranulated MCs were blindly counted by a senior pathologist, and presented as number of cells in high power field (HPF) and percentage of activated MCs. Correlation analysis was performed using Spearman rank correlation analysis. Ninety-seven patients with IBS-D were enrolled in this study, with mean age of (44±11) years. 70.10%(68 cases) of the IBS-D patients had comorbid anxiety and/or depression. The median total numbers of MCs, activated MCs, and percentage of activated MCs in sigmoid mucosa were 11.60 (7.09)/HPF, 2.00 (1.40) /HPF, and 17.50% (10.90%), respectively. Patients having abdominal pain/discomfort before bowel movement "every day with intermediate to high severity" had significantly larger numbers of total MCs in sigmoid colon compared with those with pain or discomfort "not every day and mild" [13.80(4.85)vs 7.60(5.90)/HPF, P=0.019]; the patient having "frequent" urge to have a bowel movement and mushy stools showed significantly higher percentage of activated MCs in sigmoid colon mucosa compared to those having the symptoms "some of the time" [18.75%(9.12%) vs 14.50%(13.14%), P=0.031; 21.33%(7.43%)vs 11.51%(10.65%)vs 18.42%(8.61%), P=0.030]. There was a positive correlation between the bowel movement during IBS-D onset and the percentage of activated MCs (r=0.221, P=0.030). There were no statistically significant differences in the total number of MCs and percentage of activated MCs between the patients with anxiety/depression and those without anxiety/depression (P=0.255, P=0.315). Scores of HAMA and HAMD were found not correlated with either total MCs number or percentage of activated MCs in sigmoid colon mucosa(all P>0.05). The majority of IBS-D patients had comorbid anxiety and/or depression. The total number and activation status of MCs in sigmoid colon mucosa might be related with some intestinal symptoms in IBS-D patients. Psychological disorders might influence the pathogenesis and regression of IBS-D through brain-gut axis other than MCs in sigmoid colon mucosa.