Cristofori Fernanda, Dargenio Vanessa Nadia, Dargenio Costantino, Miniello Vito Leonardo, Barone Michele, Francavilla Ruggiero
Department of Biomedical Science and Human Oncology, University of Bari Aldo Moro, Bari, Italy.
Gastroenterology Unit, Department of Emergency and Organ Transplantation, University of Bari Aldo Moro, Bari, Italy.
Front Immunol. 2021 Feb 26;12:578386. doi: 10.3389/fimmu.2021.578386. eCollection 2021.
Hosting millions of microorganisms, the digestive tract is the primary and most important part of bacterial colonization. On one side, in cases of opportunistic invasion, the abundant bacterial population inside intestinal tissues may face potential health problems such as inflammation and infections. Therefore, the immune system has evolved to sustain the host-microbiota symbiotic relationship. On the other hand, to maintain host immune homeostasis, the intestinal microflora often exerts an immunoregulatory function that cannot be ignored. A field of great interest is the association of either microbiota or probiotics with the immune system concerning clinical uses. This microbial community regulates some of the host's metabolic and physiological functions and drives early-life immune system maturation, contributing to their homeostasis throughout life. Changes in gut microbiota can occur through modification in function, composition (dysbiosis), or microbiota-host interplays. Studies on animals and humans show that probiotics can have a pivotal effect on the modulation of immune and inflammatory mechanisms; however, the precise mechanisms have not yet been well defined. Diet, age, BMI (body mass index), medications, and stress may confound the benefits of probiotic intake. In addition to host gut functions (permeability and physiology), all these agents have profound implications for the gut microbiome composition. The use of probiotics could improve the gut microbial population, increase mucus-secretion, and prevent the destruction of tight junction proteins by decreasing the number of lipopolysaccharides (LPSs). When LPS binds endothelial cells to toll-like receptors (TLR 2, 4), dendritic cells and macrophage cells are activated, and inflammatory markers are increased. Furthermore, a decrease in gut dysbiosis and intestinal leakage after probiotic therapy may minimize the development of inflammatory biomarkers and blunt unnecessary activation of the immune system. In turn, probiotics improve the differentiation of T-cells against Th2 and development of Th2 cytokines such as IL-4 and IL-10. The present narrative review explores the interactions between gut microflora/probiotics and the immune system starting from the general perspective of a biological plausibility to get to the and demonstrations of a probiotic-based approach up to the possible uses for novel therapeutic strategies.
消化道中寄居着数以百万计的微生物，是细菌定植的主要且最重要的部位。一方面，在机会性入侵的情况下，肠道组织内大量的细菌群体可能面临诸如炎症和感染等潜在健康问题。因此，免疫系统已经进化以维持宿主与微生物群的共生关系。另一方面，为了维持宿主免疫稳态，肠道微生物群通常发挥着不可忽视的免疫调节功能。一个备受关注的领域是微生物群或益生菌与免疫系统在临床应用方面的关联。这个微生物群落调节宿主的一些代谢和生理功能，并推动生命早期免疫系统的成熟，有助于维持一生的稳态。肠道微生物群的变化可通过功能改变、组成变化（生态失调）或微生物群与宿主的相互作用而发生。对动物和人类的研究表明，益生菌对免疫和炎症机制的调节可能具有关键作用；然而，确切机制尚未完全明确。饮食、年龄、体重指数（BMI）、药物和压力可能会混淆摄入益生菌的益处。除了宿主肠道功能（通透性和生理学）外，所有这些因素对肠道微生物群组成都有深远影响。使用益生菌可以改善肠道微生物群体，增加黏液分泌，并通过减少脂多糖（LPS）的数量来防止紧密连接蛋白的破坏。当LPS与内皮细胞结合至Toll样受体（TLR 2、4）时，树突状细胞和巨噬细胞被激活，炎症标志物增加。此外，益生菌治疗后肠道生态失调和肠渗漏的减少可能会使炎症生物标志物的产生最小化，并抑制免疫系统的不必要激活。反过来，益生菌可改善T细胞向Th2细胞的分化以及Th2细胞因子如IL-4和IL-10的产生。本叙述性综述从生物学合理性的一般角度出发，探讨肠道微生物群/益生菌与免疫系统之间的相互作用，直至基于益生菌方法的证据展示，以及其在新型治疗策略中的可能用途。
