Expression of 5-hydroxytryptamine 7 receptor in intestinal mucosa correlates with the degree of intestinal inflammation in Crohn’s disease

BACKGROUND: Crohn’s disease (CD), an inflammatory bowel disease (IBD), is a complex and heterogeneous disease characterized by nonspecific transmural inflammation of the gastrointestinal tract. CD has a variety of potential causes with no effective treatment available yet. Current clinical laboratory findings from patients do not provide direct indication of the status of mucosal inflammation in the intestine. Recently, it has been found that intestinal inflammation is generally associated with increased levels of 5-hydroxytryptamine (5-HT), which acts as an important gastrointestinal signaling molecule in intestinal homeostasis by stimulating specific receptors. Most previous researches were carried out in vitro or with animal models, and there was a lack of authentic clinical research. In this study, clinical specimens from patients with Crohn’s disease were used to investigate the expression of 5-hydroxytryptamine 7 receptor (5-HT7R) in the induction and development of chronic non-specific inflammatory bowel disease. METHODS: Patients with CD admitted to the Department of Gastroenterology in the First Affiliated Hospital of Anhui Medical University between June 2014 and January 2018 were recruited, among which 28 were in active disease and 32 were in remission. In addition, 20 patients who had no obvious abnormality by colonoscopy in the hospital during the same time period were recruited into the control group. Data of clinical disease activity (CDAI), CD endoscopic score (SES-CD) and magnetic resonance score (MaRIA) were collected from those two groups of patients. The expression and distribution of 5-HT7R were investigated and their correlations with clinical CDAI, MaRIA, and endoscopic SES-CD scores were analyzed. RESULTS: Our study demonstrated that 5-HT7R is expressed in intestinal neurons and CD11(C)-positive cells in human colon. In CD11c/CD86 double-positive cells in the bowel, 5-HT7R expression was significantly increased in the inflammatory area in the bowel of CD patients, and it was closely related to disease severity, MaRIA, and SES-CD scores. CONCLUSION: The expression of 5-HT7R was significantly correlated with the degree of gut inflammation in CD patients and could be a potential biomarker for disease activity and the therapeutic efficacy in patients with Crohn’s Disease.