Microbiome Impacts Immunity
How does the microbiome affect immunity, and specifically vaccine responses? Microbial-derived metabolites affect host immunity. Gut bacteria produce short chain fatty acids (SCFAs: acetate, propionate, butyrate) [115]. SCFAs positively influence immunity cells. Vitamin D metabolites are generated by intestinal bacteria and those metabolites positively influence immunity. Secondary bile acids produced by Clostridium spp. are involved in favorable immune responses. Increased levels of phenylpyruvic acid produced by gut and/or nasopharyngeal microbiota correlate with reduced vaccine responses and upregulated metabolome genes that encode for oxidative phosphorylation correlate with increased vaccine responses.
In summary, immune development commences at birth. Impairment in responses to vaccination in children have been linked to disturbance in the microbiome. Cesarean section and absence of breastfeeding are associated with adverse microbiota composition. Antibiotics perturb healthy microbiota development. The microbiota affect immunity in several ways, among them are effects by metabolites generated by the commensals that inhabit the child host. A child who responds poorly to vaccines and has specific immune cell dysfunction caused by problems with the microbiome also displays increased infection proneness. But that is a story for another column, later.
Dr. Pichichero is a specialist in pediatric infectious diseases, Center for Infectious Diseases and Immunology, and director of the Research Institute, at Rochester (N.Y.) General Hospital. He has no conflicts of interest to declare.
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