益生菌调节肠道上皮屏障功能及作用机制

动物肠道是一个具有生物多样性的微环境,单层的上皮细胞将共生微生物和病原菌与下层的免疫细胞分割构成肠道屏障。益生菌是一类对宿主有益的微生物,益生菌与肠道上皮细胞、下层免疫细胞共同构成了3个屏障,分别是机械屏障、化学屏障和免疫屏障。本文主要综述肠道上皮屏障及微生态系统组成、益生菌增强肠道上皮屏障功能作用以及微生物与肠道上皮之间的相互作用以及机制。     

肠道菌群与肠黏膜免疫屏障的相互作用研究进展

动物肠道内栖息着大量的微生物,这些微生物与宿主免疫系统间协同进化,共同维持着肠道内环境稳定。构建和维持肠道菌群与肠黏膜免疫屏障间有益的相互作用对机体健康至关重要。就肠黏膜免疫屏障的防御机制及肠道菌群与肠黏膜免疫屏障的相互作用进行综述。     

反刍动物胃肠道上皮屏障功能及与微生物互作研究

动物的胃肠道是直接与外部环境接触的部位，时刻暴露于各种外源和内源物质当中。因此，胃肠道中具有功能性上皮屏障，以防止各种物质侵入组织内部。胃肠道微生物在维持胃肠道上皮屏障稳态和强化方面发挥重要作用。胃肠道上皮屏障与微生物相互作用调节宿主胃肠道生长发育、新陈代谢和免疫功能的建立，而宿主胃肠道上皮屏障功能的建立也会影响胃肠道微生物的定殖与分布。本综述总结了胃肠道上皮屏障的结构与功能，以及胃肠道微生物和胃肠道上皮屏障之间的相互作用关系。旨在为胃肠道微生物与胃肠道上皮屏障间关系的研究提供参考。     

肠道微生物-上皮细胞屏障互作的研究进展

肠道上皮细胞（intestinal epithelial cells,IECs）是动物机体抵御病原微生物的第一道防线,是黏膜机械屏障、免疫屏障和化学屏障的重要组成部分,具有吸收和屏障双层功能。肠道中微生物数量庞大、种类繁多,根据其与宿主的关系,主要分为共生菌、条件致病菌和病原菌3类,在肠道屏障的构建中发挥重要作用。IECs首先通过直接或间接方式对肠道微生物进行识别,区别自身与非自身,对自身物质（即共生菌）免疫耐受,对非自身物质（即病原菌）产生特异性免疫反应。IECs与肠道共生菌共同抵御肠道病原微生物,维持肠道健康,病原微生物侵入肠道,IECs主要通过胞外分泌物和细胞表面黏液层双重屏障发挥作用,其中胞外分泌物主要包括黏蛋白、抗菌分子和抗微生物免疫球蛋白。肠道共生菌可以通过竞争识别位点,分泌抗菌物质,增加黏液分泌,诱导IECs更新、增殖和修复等方式抵御病原微生物,维护正常的肠黏膜屏障功能。在IECs抵御肠道病原微生物入侵过程中,病原微生物通过自身运动、分泌毒素和酶等破坏肠上皮屏障,直接接触IECs,对其进行损伤。因此IECs和肠道菌群间相互作用,共同维持肠道内环境稳态。作者就IECs和肠道微生物结构、功能的适应性变化作一综述,以期阐述肠道微生物-上皮细胞屏障互作的机制。     

茶多酚对肠道屏障功能的影响及调控机制

肠道是机体最大的免疫器官,肠道通过其屏障间相互作用抵御肠腔内容物进入肠道,维持着机体内环境的稳态及生理功能。茶多酚是茶叶中多酚类物质的总称,具有抗氧化、抗炎、抗肿瘤、增强机体免疫力等作用。茶多酚可通过调节肠道上皮细胞的表达、黏液层的分泌及改变肠道微生物的附着位点来维持机体健康。综述了茶多酚对动物肠道屏障功能的影响及调控机制,旨在为茶多酚在饲粮添加剂方面的开发和应用提供理论依据。     

肠道菌群与动物免疫的相互关系

肠道菌群形成了一个庞大而复杂的微生态系统,与动物免疫之间的关系极为密切.正常的肠道菌群具有屏障作用,与肠道黏膜的免疫作用、免疫器官的生长发育及免疫因子的激活都有关系.本文对肠道菌群的分布、肠道菌群对动物免疫的影响及抗生素、肠道菌群与动物免疫之间的相互作用等方面做了综述.     

乳酸杆菌在调节肠道屏障功能中的作用

乳酸杆菌不仅是动物肠道内存在的正常微生物,也是益生菌的重要组成部分。肠道屏障主要是由肠道黏膜免疫系统组成的免疫屏障、肠黏液层和肠上皮细胞层组成的肠黏膜物理屏障及肠道微生物构成的生物屏障构成。作者综述了近年来国内外有关乳酸杆菌制剂对肠道屏障功能调控作用的研究进展。     

肠道菌群与肠上皮细胞互作关系的研究进展

肠道菌群数量大、种类繁多，会对宿主产生各种各样的影响，包括营养代谢、免疫系统调节和抵御感染等，在维持肠道稳态平衡中起着重要作用。肠道上皮细胞是肠道防御系统的关键。肠道上皮是动物机体抵御微生物的第一道屏障，具有吸收和屏障功能，还是宿主与微生物群交流的主动传感器，而这样的功能是肠道菌群与肠上皮各类细胞间相互作用的结果。论文以肠道菌群与肠上皮细胞中的几类典型细胞之间的互作关系展开论述，旨在为如何通过各类细胞发挥的功能来协调肠道菌群的稳定，进而为预防或治疗某些由于肠道菌群失调而导致的疾病提供理论依据。     

抗生素对消化道微生物及其免疫系统的影响北大核心

滥用抗生素会引起动物肠道菌群失调,影响动物免疫。通过对肠道微生物的组成,研究肠道微生物和哺乳动物的免疫系统之间的相互作用,为研究抗生素诱导菌群和免疫稳态失衡打下理论基础。     

真菌多糖益生元干预家禽肠道微生物调控肠道屏障功能的研究进展

家禽肠道微生物作为肠道黏膜屏障的重要组成部分在宿主的肠道屏障功能维持和肠道健康稳定中发挥重要作用。益生菌和益生元是调控肠道微生物的有效手段,其中真菌多糖作为天然代谢产物,具有抗氧化、增强免疫等多种生物活性,是一种重要的潜在益生元,其在鸡体内无法直接消化利用,主要通过肠道微生物进行发酵降解,并产生相关代谢产物,真菌多糖与肠道微生物的相互作用会对肠道屏障功能产生积极影响。文章在简要概述家禽肠道微生物的定植和影响因素、家禽肠道黏膜屏障功能及其干预调控手段的基础上,重点阐述了潜在益生元真菌多糖干预家禽肠道微生物对肠道屏障功能的调控作用,为家禽肠道健康调控奠定理论基础,并为真菌多糖产品的开发提供参考。     

Chronic intestinal inflammation and intestinal disease in dogs

Normal individuals maintain tolerance to the endogenous bacterial flora residing within their alimentary tract, a phenomenon mediated by the gastrointestinal lymphoid tissue. Loss of this tolerance is a key factor in the development of chronic intestinal inflammation. Manifestations of such uncontrolled inflammation in humans include inflammatory bowel disease and celiac disease. Dogs may similarly be affected, and although the etiopathogenesis is likely similar, the lesions differ. This review includes discussion of the factors involved in breakdown of mucosal tolerance, the immunologic basis of canine enteropathies, and the use of novel immunotherapies for these diseases.     

Determination of intestinal viability

Operations for intestinal ischemia are frequently done by veterinarians. In equine surgery those conditions commonly producing ischemia are intussusception, volvulus, bowel obstructions, and incarcerated hernias. In an attempt to predict intraoperative bowel viability after the restoration of circulation, a variety of adjuvant methods have been investigated. There is little question that of the techniques currently available, sodium fluorescein injected intravenously approaches the ideal in predicting nonviability in humans and in most animal models. Furthermore, it is safe, takes little operating time, is inexpensive, and is ubiquitously available; in addition, the only special equipment needed is a long-wave ultraviolet lamp. Reliance on this method would seldom result in nonviable bowel being left in situ. Furthermore, the use of fluorescein would minimize the unnecessary resection of viable intestine and, thereby, minimize the postoperative nutritional problems that may occur, especially in equines. The report of Sullins et al questions the accuracy of the fluorescein technique in predicting viability and nonviability in horses and also raises the question as to whether the prediction of viability, after the restoration of intestinal blood flow, also predicts normal intestinal function. Further investigations will be needed to confirm or refute these observations.     

Small intestinal morphology and activity of intestinal peptidases in piglets around weaning

The effect of weaning on small intestinal morphology and the activities of three intestinal peptidases was investigated from 3 days prior to weaning to 9 days post-weaning in 64 piglets. Villous height, crypt depth and mitotic counts were determined at three positions along the small intestine. The activities of aminopeptidase N, dipeptidylpeptidase IV and gamma-glutamyl transpeptidase were measured at five positions along the small intestine. The villous height was maximal on the day of weaning. Post-weaning, the villi shortened at the proximal positions of the small intestine and the minimal length was observed on day 3 after weaning. Villous height did not decrease distally in the small intestine. Increased crypt depth was observed from 3-7 days post-weaning at all positions examined. Mitotic counts showed increased proliferative activity in the crypts from the third day post-weaning. Weaning influenced the activity of aminopeptidase N and dipeptidylpeptidase IV. The activities declined until day 3 post-weaning. After that, the activities increased and they had reached pre-weaning values by day 9 post-weaning. Weaning had only minor effect on the activity of gamma-glutamyl transpeptidase. In summary, weaning induced changes in small intestinal morphology and enzyme activity. The changes were maximal on day 3 post-weaning and during the following days, a gradual recovery of the small intestine was observed.     

Normal intestinal motility

Perhaps because of the inherent difficulty in using horses as experimental animals, only a relatively small amount of data is as yet available regarding normal equine gut motility. However, it is clear that the horse is fundamentally similar to other mammalian species studied. The neural and humoral control of gut activity requires much exploration; it is likely that, in the horse, some of this information will be derived during the investigation of the effects of various substances that might have clinical relevance. This is alluded to in the chapter that follows (The Effects of Pharmacological Agents on Gastrointestinal Motility). The clinical applications are likely to remain limited, though some light may be shed upon the derivation of certain disorders.     

Canine intestinal carcinoids

Intestinal carcinoids were diagnosed in three aged dogs. Two of the neoplasms occurred in the rectum and one at the cecocolic junction. Judged by histologic criteria, all three carcinoids were considered to be malignant. Amyloid was present in both rectal tumors. In each tumor the diagnosis was confirmed by the finding of electron-dense intracytoplasmic secretory granules in the neoplastic cells.     

Bovine intestinal surgery

A clear understanding of the surgical anatomy of the bovine intestinal tract is the most important factor in determining the degree of success to be achieved in the surgical management of intestinal disorders in cattle. However, bovine intestinal anatomy can be very difficult to comprehend, especially in cattle with intestinal distention and malposition. The abundance of mesenteric and omental fat and the compact nature of the mesentery make manipulation and exteriorization of many parts of the bowel difficult. Therefore, it is important to accurately identify specific surgical landmarks. A good working knowledge of the relevant surgical anatomy increases the level of confidence in one's surgical abilities and makes one more willing to consider surgical intervention in a cow with suspected GI dysfunction.