Montalto M, Veneto G, Cuoco L, Cammarota G, Tursi A, Papa A, Fedeli G, Gasbarrini G
Cattedra di Medicina Interna II, Università Cattolica del Sacro Cuore, Roma.
Recenti Prog Med. 1997 Mar;88(3):140-7.
Intestinal mucosa has an absorptive function and acts also as a selective barrier against potential antigenic, toxic and carcinogenic substances. Intestinal permeability can be defined as the capacity of mucosal surface to be penetrate by specific substances through unmediated diffusion. There are two theories about molecular permeation routes: the first one hypothesizes a transcellular (through small pores), a paracellular (through big channels) and a lipophilic pathways; the second one gives a key role only to paracellular tight-junctions. In many diseases we can find changes in intestinal permeability evaluable by simple and non invasive tests, administering "per os" probe molecules. These substances cross the epithelium in different way and amount according to their physicochemical features and mucosal integrity; then they reach circulation and are eliminated in urines where they can be detected. The most frequently molecules used are mono/disaccharides, 51Cr-labelled ethylenediaminetetraacetate (51Cr-EDTA) and polyethylene glycol (PEG). This simple method has become more and more used for diagnostic and speculative aims. These intestinal permeability tests have a low specificity so they cannot be used for a definitive diagnosis of intestinal disease; nevertheless, the high sensitivity for intestinal mucosal damage could make them a necessary method to evaluate mucosal integrity after therapy, to select patients with a specific symptoms and to support, particularly in pediatric populations, more specific and invasive diagnostic tests.
肠黏膜具有吸收功能，同时还作为一道选择性屏障，抵御潜在的抗原性、毒性和致癌物质。肠道通透性可定义为黏膜表面通过特定物质经非介导扩散而被穿透的能力。关于分子渗透途径有两种理论：第一种假设存在跨细胞（通过小孔）、细胞旁（通过大通道）和亲脂性途径；第二种则仅赋予细胞旁紧密连接关键作用。在许多疾病中，我们可以通过简单且无创的测试来评估肠道通透性的变化，即口服探针分子。这些物质根据其物理化学特性和黏膜完整性，以不同方式和数量穿过上皮细胞；然后它们进入循环系统，并在尿液中被检测到。最常使用的分子是单糖/双糖、51铬标记的乙二胺四乙酸（51Cr-EDTA）和聚乙二醇（PEG）。这种简单方法已越来越多地用于诊断和推测目的。这些肠道通透性测试特异性较低，因此不能用于肠道疾病的确诊；然而，其对肠黏膜损伤的高敏感性使其成为评估治疗后黏膜完整性、筛选具有特定症状的患者以及特别是在儿科人群中辅助更具特异性和侵入性的诊断测试的必要方法。
