The gut microbiota can significantly affect the function of the intestinal barrier. Some intestinal probiotics (such as Lactobacillus, Bifidobacteria, a few Escherichia coli strains, and a new generation of probiotics including Bacteroides thetaiotaomicron and Akkermansia muciniphila) can maintain intestinal epithelial homeostasis and promote health. This review first summarizes probiotics' regulation of the intestinal epithelium via their surface compounds. Surface layer proteins, flagella, pili and capsular polysaccharides constitute microbial-associated molecular patterns and specifically bind to pattern recognition receptors, which can regulate signaling pathways to produce cytokines or inhibit apoptosis, thereby attenuating inflammation and enhancing the function of the gut epithelium. The review also explains the effects of metabolites (such as secreted proteins, organic acids, indole, extracellular vesicles and bacteriocins) of probiotics on host receptors and the mechanisms by which these metabolites regulate gut epithelial barrier function. Previous reviews summarized the role of the surface macromolecules or metabolites of gut microbes (including both probiotics and pathogens) in human health. However, these reviews were mostly focused on the interactions between these substances and the intestinal mucosal immune system. In the current review, we only focused on probiotics and discussed the molecular interaction between these bacteria and the gut epithelial barrier.

中文翻译：

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益生菌的表面成分和代谢物调节肠上皮屏障。

肠道微生物群可以显着影响肠道屏障的功能。一些肠道益生菌（如乳酸菌、双歧杆菌、少数大肠杆菌菌株以及新一代益生菌包括多形拟杆菌和粘蛋白阿克曼氏菌）可以维持肠上皮稳态，促进健康。本综述首先总结了益生菌通过其表面化合物对肠上皮的调节作用。表层蛋白、鞭毛、菌毛和荚膜多糖构成了微生物相关的分子模式，并与模式识别受体特异性结合，可以调节信号通路产生细胞因子或抑制细胞凋亡，从而减轻炎症并增强肠道上皮的功能。该综述还解释了益生菌代谢物（如分泌蛋白、有机酸、吲哚、细胞外囊泡和细菌素）对宿主受体的影响以及这些代谢物调节肠道上皮屏障功能的机制。之前的综述总结了肠道微生物（包括益生菌和病原体）的表面大分子或代谢物在人类健康中的作用。然而，这些评论主要集中在这些物质与肠粘膜免疫系统之间的相互作用。在当前的综述中，我们仅关注益生菌并讨论这些细菌与肠道上皮屏障之间的分子相互作用。