Understanding the complex interplay between the microbiota and immunity is only just beginning
By Dr Bruce Vallance
About this article
Your body is home to trillions of bacteria that together with viruses, fungi and other organisms, collectively make up the human microbiota.
These microbes play an important role in promoting our health, as well as controlling our susceptibility to disease, by influencing different aspects of our daily lives. For example, the metabolic activity of our gut microbiota determines whether certain medications like acetaminophen are toxic to our livers.1 Specific members of the microbiota can also change and evolve in response to new dietary sources of carbohydrates, allowing us to digest foods like sushi2 or produce important and protective chemicals such as short chain fatty acids (SCFA).3 Other microbes selectively shape our immune systems to become reactive, or tolerant to invading organisms, thereby controlling our risk of severe gastrointestinal (GI) infections.4
During the 1000 first days of life, the critical window of early childhood growth and development (period from conception to 2 years of age), any interference with microbiota establishment in the neonatal gut may potentially lead to negative health outcomes.5
1000 first days of life critical window of early childhood growth and development
Although scientists have established the importance of the microbiota in maintaining human health, our understanding of the complex interplay between the microbiota and immunity is only just beginning.
1 Clayton TA, Baker D, Lindon JC, et al. Pharmacometabonomic identification of a significant host-microbiome metabolic interaction affecting human drug metabolism. Proc Natl Acad Sci U S A. 2009 Aug 25;106(34):14728-33.
2 Hehemann JH, Kelly AG, Pudlo NA, et al. Bacteria of the human gut microbiome catabolize red seaweed glycans with carbohydrate-active enzyme updates from extrinsic microbes. Proc Natl Acad Sci U S A. 2012 Nov 27;109(48):19786-91.
3 Yang W, Yu T, Huang X, et al. Intestinal microbiota-derived shortchain fatty acids regulation of immune cell IL-22 production and gut immunity. Nat Commun. 2020 Sep 8;11(1):4457.
4 Atarashi K, Tanoue T, Shima T, et al. Induction of colonic regulatory T cells by indigenous Clostridium species. Science. 2011 Jan 21;331(6015):337-41.
5 Aires J. First 1000 Days of Life: Consequences of Antibiotics on Gut Microbiota. Front Microbiol. 2021 May 19;12:681427.