NHMRC Centre of Research Excellence in Digestive Health, The University of Newcastle, Callaghan, New South Wales, Australia.
College of Health, Medicine and Wellbeing, The University of Newcastle, Callaghan, New South Wales, Australia.
BMC Med. 2022 Mar 31;20(1):115. doi: 10.1186/s12916-022-02301-8.
Irritable bowel syndrome (IBS) is considered a disorder of gut-brain interaction (DGBI), presenting as chronic abdominal pain and altered defaecation. Symptoms are often food related. Much work in the field has focused on identifying physiological, immune and microbial abnormalities in the colon of patients; however, evidence of small intestinal immune activation and microbial imbalance has been reported in small studies. The significance of such findings has been largely underappreciated despite a growing body of work implicating small intestinal homeostatic imbalance in the pathogenesis of DGBIs.
Small intestinal mechanosensation is a characteristic feature of IBS. Furthermore, altered small intestinal barrier functions have been demonstrated in IBS patients with the diarrhoea-predominant subtype. Small intestinal bacterial overgrowth and increased populations of small intestinal mast cells are frequently associated with IBS, implicating microbial imbalance and low-grade inflammation in the pathogenesis of IBS. Furthermore, reports of localised food hypersensitivity responses in IBS patients implicate the small intestine as the site of immune-microbial-food interactions.
Given the association of IBS symptoms with food intake in a large proportion of patients and the emerging evidence of immune activation in these patients, the current literature suggests the pathogenesis of IBS is not limited to the colon but rather may involve dysfunction of the entire intestinal tract. It remains unclear if regional variation in IBS pathology explains the various symptom phenotypes and further work should consider the intestinal tract as a whole to answer this question.
肠易激综合征（IBS）被认为是一种肠脑相互作用障碍（DGBI），表现为慢性腹痛和排便习惯改变。症状常与食物有关。该领域的大量工作集中在识别患者结肠中的生理、免疫和微生物异常；然而，在一些小型研究中已经报道了小肠免疫激活和微生物失衡的证据。尽管越来越多的工作表明小肠稳态失衡与 DGBI 的发病机制有关，但这些发现的意义在很大程度上仍未得到重视。
小肠机械感觉是 IBS 的一个特征。此外，腹泻为主型 IBS 患者的小肠屏障功能已发生改变。小肠细菌过度生长和小肠肥大细胞增多常与 IBS 相关，提示微生物失衡和低度炎症在 IBS 的发病机制中起作用。此外，IBS 患者局部食物过敏反应的报道提示小肠是免疫-微生物-食物相互作用的部位。
鉴于相当一部分 IBS 患者的症状与食物摄入有关，且这些患者的免疫激活证据不断涌现，目前的文献表明 IBS 的发病机制不仅局限于结肠，而可能涉及整个肠道的功能障碍。IBS 病理学的区域差异是否能解释各种症状表型尚不清楚，进一步的研究应将整个肠道作为一个整体来回答这个问题。
