PROJECT SUMMARY The early life immune system requires “training” to decrease vulnerability to infectious diseases and is the time period when risks for development of non-communicable, immune-mediated diseases, such as allergic diseases, are established. Early life exposure to the farming environment has been shown to provide a protective role against the development of allergic diseases. We have successfully established a novel birth cohort called Wisconsin Infant Study Cohort (WISC). WISC is a rural US birth cohort with infants from dairy farms, rural, non- farming environments, and infants from Amish communities who have a very Traditional Agrarian (TA) lifestyle. Our study findings demonstrate decreased incidence of atopic dermatitis, decreased viral respiratory illness frequency and increased LPS-induced monocyte cytokine production during the first year of life in farm-exposed infants. Our preliminary data demonstrate TA children have very low rates of allergic disease, unique gut and nasal microbiota, and increased innate maturation and immune regulatory markers compared to farm and non- farm children through age 2 years. There remain unresolved and important questions as to whether and how innate immune cell competence and immunoregulatory function are related in early life and their risk for disease. A major goal of this proposal is to define the immune and environmental signatures for protection from allergic and viral respiratory diseases in farm exposed children and determine the relationship between immune, nasal epithelial profiles and microbiome. Our central hypothesis is that farm-related microbial colonization promotes the development of distinct immune and nasal epithelial phenotypes mediated, in part, through epigenetic changes that reduce risk for allergic sensitization and increase mucosal antiviral responses. We hypothesize the Amish will have distinct immune profiles and microbial exposures, the farm participants will be intermediaries, and non-farm considered a relatively at-risk study group. To address this hypothesis, we will continue WISC+ through age 5 years and establish a new cross-sectional cohort. Our study consists of three aims and makes use of cutting-edge technologies that leverages our extensive experience with farm-related birth cohorts and study team expertise. Aim 1. To characterize the longitudinal phenotypes and epigenetic trajectory of monocyte and regulatory immune cells of the TA, farm and non-farm children through age 5 years. Aim 2. To determine the relationship between TA and farm exposures, nasal airway epithelial cell gene expression and response to naturally occurring viral respiratory illness. We will conduct an observational, cross-sectional, case- control cohort study (called Microbial Associated Respiratory Illnesses, MARI) of three groups of school-age children (100/group): TA children, suburban children without asthma, and suburban children with asthma to examine nasal mucosal physiology, a...