【摘要】 背景:腹泻型肠易激综合征(IBS-D)患者的症状具有昼夜波动等节律紊乱特征，但其病理生理学机制尚不清楚。目的:探讨结肠生物钟基因Bmal1在IBS-D患者症状发生中的作用及其可能机制。方法:于2018年9月—2021年2月在陆军特色医学中心纳入46例IBS-D患者和34例正常对照者参与研究。以IBS严重程度评分系统(IBS-SSS)评估患者病情严重程度。结肠镜检查时在直肠乙状结肠交界处取活检，以ELISA法检测5-羟色胺(5-HT)含量，免疫荧光双标技术检测Bmal1和肠嗜铬细胞(EC细胞)标记物嗜铬粒蛋白A(CgA)表达。结果:IBS-D患者结肠黏膜中的5-HT含量、EC细胞数量均显著高于正常对照组(P均<0.05)。Bmal1主要表达于肠上皮细胞，其与CgA存在共表达，且在EC细胞中呈高表达。与同时间点取材的正常对照组相比，上午9∶00取材的IBS-D患者结肠Bmal1表达显著升高，下午17∶00取材者Bmal1表达则显著降低(P均<0.05)。Spearman相关系数分析显示，上午9∶00取材的IBS-D患者结肠Bmal1表达与IBS-SSS总分和腹痛不适评分呈显著正相关(r_s=0.413,P=0.023;r_s=0.546,P=0.001)。结论:IBS-D患者存在结肠生物钟基因Bmal1表达紊乱，Bmal1振荡或可通过影响EC细胞的5-HT分泌参与IBS-D症状发生。更多还原

【Abstract】 Background: Symptoms of irritable bowel syndrome with diarrhea(IBS-D) are known to be influenced by circadian oscillation; however, the pathophysiological mechanism is still unclear. Aims: To investigate the role and underlying mechanism of colon circadian clock gene Bmal1 involved in the occurrence of symptoms in IBS-D patients. Methods: Forty-six patients with IBS-D and 34 normal controls from Army Medical Center of PLA during September 2018 to February 2021 were recruited in this study. IBS-severity scoring system(IBS-SSS) was used to evaluate the severity of IBS-D symptoms. A colonoscopy was performed to obtain biopsy specimens from rectosigmoid colon. The concentration of 5-hydroxytryptamine(5-HT), and expressions of Bmal1 and chromogranin A(CgA), a biomarker of enterochromaffin cells(EC cells), in colonic mucosa were detected by ELISA and double-labeled immunofluorescence, respectively. Results: Both the 5-HT concentration and number of EC cells in colonic mucosa of IBS-D patients were significantly higher than those of the normal controls(all P<0.05). Bmal1 was mainly expressed in intestinal epithelial cells and was highly expressed in EC cells. Co-expression of Bmal1 and CgA was observed. Compared with the normal control group biopsied at the same time point, expression of Bmal1 was significantly higher in specimens taken at 9 a.m., and expression of Bmal1 was significantly lower in specimens taken at 17 p.m. in IBS-D patients(all P<0.05). Spearman correlation coefficient analysis showed that Bmal1 expression at 9 a.m. was positively correlated with the total score of IBS-SSS and subscore of abdominal pain and discomfort(r_s=0.413, P=0.023; r_s=0.546, P=0.001) in IBS-D patients. Conclusions: Colon circadian clock gene Bmal1 is aberrantly expressed in patients with IBS-D. Bmal1 oscillation might be involved in the pathogenesis of IBS-D symptoms via regulating the secretion of 5-HT in EC cells.更多还原