Microbiome Influenced by Genetic Differences in Immune System

Scientists headed by a team at the University of Chicago have shown how genetic differences in the immune system can impact on the types of bacterial communities that colonize the gastrointestinal system. Their studies, in germ-free mice colonized with microbiomes from conventionally reared animals, found that while the makeup of the donor microbiome was the key factor in determining the recipient microbiome, genetic differences in the immune systems of the recipients also played a role. “When the input is standardized, you can compare mice of different genetic strains and see what these genetics do to the microbiome in recipient mice,” said Alexander Chervonsky, MD, PhD, who is a senior author of the team’s study, which is published in Cell Reports. “This approach allowed us to tell whether there was a genetic influence, and indeed there is.” Chervonsky and colleagues report their findings in a paper titled, “Polymorphic Immune Mechanisms Regulate Commensal Repertoire.” The bacteria that naturally live in and on us provide essential functions that are required for our very survival, the authors wrote. The composition of microbial communities varies between individuals and is influenced by a range of factors, including “… the mode of transmission during birth, breastfeeding, alimentary infections, and diet.” Previous studies have suggested that host genetics can also impact on microbial communities—identical twins tend to have more similar microbiomes than do non-identical twins—but, as the team continued, “ … two important questions remain unanswered: to what extent and which host’s polymorphic mechanisms are involved in shaping the repertoire of the commensals.”