Department of Medical Sciences, University of Turin, Turin, Italy.
Unit of Gastroenterology, Molinette Hospital, Turin, Italy.
Minerva Gastroenterol (Torino). 2022 Mar;68(1):98-110. doi: 10.23736/S2724-5985.20.02808-1. Epub 2020 Dec 3.
In recent years, there has been growing interest in the comprehension of the physiology of intestinal permeability and microbiota; and how these elements could influence the pathogenesis of diseases. The term intestinal permeability describes all the processes that allow the passage of molecules as water, electrolytes and nutrients through the intestinal barrier by the paracellular or the transcellular transport systems with several implications for self-tolerance and not-self immunity. An increased permeability might induce a more significant interaction of the immune system with unknown external antigens. This might favor the onset of several immune-related extra-intestinal diseases including coeliac disease, diabetes mellitus type 1, bronchial asthma and inflammatory bowel diseases. Furthermore, the intestinal permeability interacts every day with microbiota, the complex system of mutualistic inhabitants and commensal microorganisms living in the healthy gut. Microbiota is implicated in physiological functions by actively participating in digestion, absorption, synthesis of vitamins and protection from external aggressions. The critical site where these processes occur is the small intestine to which this updated review is dedicated. Understanding its anatomy, its barrier structure and permeability modulation and its microbiota composition is the essential skill to comprehend the complex pathogenesis of several - not only gastroenterological - diseases.
近年来，人们对肠道通透性和微生物群的生理学理解越来越感兴趣；以及这些因素如何影响疾病的发病机制。肠道通透性这个术语描述了所有允许水分子、电解质和营养物质通过肠道屏障的过程，这些过程通过旁细胞或细胞内运输系统进行，对自身耐受和非自身免疫有多种影响。通透性的增加可能会导致免疫系统与未知的外部抗原发生更显著的相互作用。这可能会导致几种与免疫相关的肠外疾病的发生，包括乳糜泻、1 型糖尿病、支气管哮喘和炎症性肠病。此外，肠道通透性每天都与微生物群相互作用，微生物群是生活在健康肠道中的共生居民和共生微生物的复杂系统。微生物群通过积极参与消化、吸收、维生素合成和抵御外部侵袭来发挥生理功能。这些过程发生的关键部位是小肠，这也是本篇更新综述的主题。了解其解剖结构、屏障结构和通透性调节以及微生物群组成，是理解多种疾病（不仅是胃肠道疾病）复杂发病机制的必要技能。
