Developmental signifi cance of early gut-associated lymphoid tissue (GALT)- microbiota interactions in health and disease: Creating balance between tolerance and infl ammation in children

Abstract

The establishment of gut microbiota in humans does not occur randomly but develops after birth through highly organized interactions between microorganisms, the immune processes orchestrated by the Gut-Associated Lymphoid Tissue (GALT), and a selective absorption to the blood regulated by the Gastrointestinal-Blood Barrier (GIB). In term infants, the initial colonization of gut microorganisms depends on the maturation of the GALT and critical closure of GIB and these interactions lead to the establishment of symbiotic conditions defi ned as a balance between immunity and infections. In preterm infants, development of the GALT is less complete at birth, and the GIB closure is delayed, both of which impact gut microbiota colonization resulting in dysbiosis. Early developmental dysbiosis may underlie non-infectious diseases such as allergies, autoimmune diseases, or infl ammatory bowel diseases and contribute to the pathology of neurodevelopmental disorders. This review focuses on the developmental signifi cance of GALT-microbiota interaction while comparing preterm and term infants. It concludes with the premiss that the developmental dysbiosis may have both short-and long-term impact on human health.

Cross-talk between immune system and microbiota in COVID-19

“…The first colonization of gut microorganisms in full-term infants depends on GALT maturation and GI-Blood Barrier critical closure. These interactions result in the formation of symbiotic conditions, which are defined as a balance between immunity and infections [ 84 ].…”

Chronic Exposure to Both Electronic and Conventional Cigarettes Alters Ileum and Colon Turnover, Immune Function, and Barrier Integrity in Mice

“…Since tight junctions are essential to maintain the cohesion and impermeability of the intestinal epithelium, a reduction in tight junctions by smoke exposure could disturb the homeostasis of gut microbiota and thus favour dysbiosis. Gut microbiota has a key role in gut-associated lymphoid tissue maturation and development, and there is communication with local immune cells to shape specific responses by balancing the tolerance and effector immune functions with various antigens [ 46 ]. A weakened gut barrier also promotes the translocation of pathogens through the intestinal mucosa and can increase susceptibility to infection.…”

From Intrauterine to Extrauterine Life—The Role of Endogenous and Exogenous Factors in the Regulation of the Intestinal Microbiota Community and Gut Maturation in Early Life

“…This is especially significant in the context of beneficial bacteria immune regulation, such as Bifidobacteria and Lactobacilli present in the human placenta (31,32). Microbiota colonization is associated with gut-associated lymphoid tissue (GALT) development (33). Toll-like receptors (TLRs) present on the surface of various cells (macrophages, mast cells, and dendritic cells) may recognize distinct bacteria driving the development of a potential inflammatory response (5).…”

“…Fetal microbiota, or their molecular signatures, may form mucosal immunity and prepare the tissues for colonization following birth (18). The maternal microbes and their metabolites have impact on immunity development by epigenetic modifications influencing Th1/Th2 balance, production of SCFAs that may induce T-cell activation and modulate IL-10 release, as well as regulation of TLRs (5,(33)(34)(35). (B,C) Vaginal delivery assures own mother's vaginal microbiota colonization.…”