Funding Source: National Institutes of Health 1R15AI160139-01A1 – Despite affecting nearly 20% of infants in the United States, there is no cure for atopic dermatitis/eczema. Some parents feed their infants human milk in an effort to protect the infant from developing this disease, but the efficacy of this intervention is unclear. This project will determine if the presence of specific bacterial genes or bacterial metabolic products in the intestinal tract during early life in two different infant cohorts, while the immune system is still fully developing, can protect the infant from atopic dermatitis/eczema. Much of this work will be carried out by students at Wellesley College and undergraduate students at Michigan State University. Performing this research in two different regions of the US will be especially advantageous, since subtle differences in medical or cultural practices, or simply geographic differences in microbial exposure, may alter HMO metabolizing gene repertoires independent of breastfeeding behavior. This research will dramatically improve our understanding of microbial HMO metabolism in human infants in the United States and determine whether a specific pattern of HMO metabolizing genes protects infants from atopic dermatitis and eczema.