Researchers Tie Gut Microbiota and IL-17 Variants to AD in Infants

A recent study’s findings highlight an association between increased levels of Streptococcus and the interleukin (IL)-17 variant rs2275913 and the development of atopic dermatitis (AD). According to the researchers, the study is the first to describe a relationship between these factors and the development of AD in infants using multiomics.

Although more understanding of the etiology of AD—whose prevalence has increased significantly in recent decades—is needed, it is believed that various interacting factors play a role, including genetic and environmental factors, with the latter contributing to changes in the gut microbiota and a subsequent change in the immune system.

“Many recent studies have indicated that the gut microbiota is involved in the pathogenesis of allergic diseases, including AD, in infants,” explained the authors of the current study. “These data imply that the gut microbiota play a critical role in the development of AD.”

A close examination of the gut microbiota of 60 infants with AD and 90 healthy infants showed that Streptococcus was significantly increased in infants with AD, as was Lactobacillus. Meanwhile, Clostridium, Clostridium g4, and Clostridium g6 were enhanced in the normal healthy group.

With prior research also implicating the IL-17 variant rs2275913 in the development of AD, the researchers analyzed the impact of the variant to see whether the gut microbiota is affected by it and whether the interaction of the two plays a role in the development of AD.

After adjusting for the diagnosis of AD, delivery mode, and feeding type, the researchers found that Streptococcus was enriched in the GA + AA genotype of the IL-17 variant. They also observed that Streptococcus was enhanced in the infants with AD who harbored the GA + AA genotype compared with the healthy infants with the GG genotype of IL-17.

There was a positive correlation between Streptococcus abundance and both the level of total IgE and the scoring AD index score in the infants with AD who had the GA + AA genotype of the IL-17 variant but not in those with the GG genotype. On the other hand, an abundance of Streptococcus was not associated with the level of total immunoglobin E in healthy patients regardless of the IL-17 variant.

The researcher of the study say their findings “suggest the possibility that alteration of the gut Streptococcus, which may be mediated in part by IL-17 host genetic variants, can contribute to the development of AD in infants via intestinal and systemic inflammation and a reduction in [short-chain fatty acid].”

Reference

Kang M, Lee S, Park Y, et al. Interactions between IL-17 variants and Streptococcus in the gut contribute to the development of atopic dermatitis in infancy. Allergy Asthma Immmunol Res. 2021;13(3):404-419. doi:10.4168/aair.2021.13.3.404