Gut Microbiota and Immune System Interactions

Abstract

Dynamic interactions between gut microbiota and a host’s innate and adaptive immune systems play key roles in maintaining intestinal homeostasis and inhibiting inflammation. The gut microbiota metabolizes proteins and complex carbohydrates, synthesize vitamins, and produce an enormous number of metabolic products that can mediate cross-talk between gut epithelial and immune cells. As a defense mechanism, gut epithelial cells produce a mucosal barrier to segregate microbiota from host immune cells and reduce intestinal permeability. An impaired interaction between gut microbiota and the mucosal immune system can lead to an increased abundance of potentially pathogenic gram-negative bacteria and their associated metabolic changes, disrupting the epithelial barrier and increasing susceptibility to infections. Gut dysbiosis, or negative alterations in gut microbial composition, can also dysregulate immune responses, causing inflammation, oxidative stress, and insulin resistance. Over time, chronic dysbiosis and the translocation of bacteria and their metabolic products across the mucosal barrier may increase prevalence of type 2 diabetes, cardiovascular disease, inflammatory bowel disease, autoimmune disease, and a variety of cancers. In this paper, we highlight the pivotal role gut microbiota and their metabolites (short-chain fatty acids (SCFAs)) play in mucosal immunity.

Gut Microbiota Comparison Between Intestinal Contents and Mucosa in Mice With Repeated Stress-Related Diarrhea Provides Novel Insight

“…A latest finding was reported that mucosal-associated invariant T (MAIT) cells interact with local microbiota and integrate multiple signals, so it plays an important role in local inflammation ( Ioannidis et al, 2020 ). The microbiome at homeostasis colonized in intestinal mucosa can antagonize pathogenic bacteria, clear endotoxin, and play a role of resistance to external environmental factors ( Seo et al, 2020 ); in turn, the intestinal epithelial cells can also affect the community structure of intestinal mucosal microbiota ( Yoo et al, 2020 ). These researches all explain why intestinal mucosal microbiota in this study is highly susceptible to repeated stress-related diarrhea.…”

Miracle Berry as a Potential Supplement in the Control of Metabolic Risk Factors in Cancer

“…The diet and metabolic statuses of individuals are key factors affecting the diversity and composition of the microbiome [ 13 , 14 ]. In this way, effective management of the nutritional and metabolic status at the systemic level contribute to promoting a healthy gut microbiome, thereby diminishing the risk of intestinal inflammatory diseases such as ulcerative colitis, inflammatory bowel disease, and cancer [ 15 , 16 , 17 , 18 ]. The microbiota have been demonstrated to influence body weight control by affecting the extraction and absorption of calories, influencing the secretion of anorexigenic hormones (GLP-1, PYY, and leptin), and controlling the intestinal gut barrier [ 19 ].…”

Young at Gut—Turning Back the Clock with the Gut Microbiome

“…Gut microbial communities of children, adults, the elderly, and centenarians have been found to cluster apart from one another other [ 12 , 13 ], suggesting that the gut microbial communities may in fact play different roles throughout the aging process. The development of age-related diseases is often associated with gut dysbiosis, changes in the gut microbiota that negatively impact host health [ 14 , 15 ]. Furthermore, aging is typically associated with decreased diversity and Firmicutes to Bacteroides ratio, as well as an increase in some Proteobacteria, opportunistic species, and pathobionts [ 12 , 16 , 17 , 18 , 19 , 20 , 21 ].…”