The “Developmental Origin of Health and Disease” (DOHaD) hypothesis posits that early life exposures (nutritional, environmental, inflammatory) influence offspring susceptibility to a number of non-communicable diseases. Allergic asthma, a disease affecting >300 million people, continues to increase in prevalence. Consistent with the DoHAD hypothesis, maternal and paternal exposures can influence both risk and severity of offspring asthma. Maternal exposures to environmental factors can influence offspring asthma by modifying the epigenome in offspring T cells and dendritic cells. In contrast, while specific paternal exposures (tobacco smoke, employment in specific occupations) alter offspring asthma risk in humans, the cell types impacted in offspring are unknown. Our novel preliminary data demonstrate that pre-conceptual paternal HDM exposure to the allergen house dust mite (HDM) is associated with a reduced asthma severity and increased recruitment of Rorgt- expressing gd T cell populations in offspring, and that depletion of offspring gd T cells abrogates the protective effect of paternal allergen exposure. While paternal exposures have been demonstrated to influence offspring behavior, and/or development of metabolic dysfunction in animal models, our innovative preliminary data are the first to demonstrate that paternal exposures to allergens influence chronic inflammatory responses in offspring. As gd T cell depletion reversed the protective effects of paternal allergen exposure, we hypothesize that paternal HDM exposure reduces offspring asthma severity by altering the phenotype and function of Rorgt-expressing gd T cell populations present in the lung. This innovative hypothesis will be tested in two independent, yet related specific aims. Aim 1: To determine if Rorgt-expressing gd T cells are necessary and sufficient to reduce airway hyper-responsiveness in offspring of HDM-exposed fathers, we will 1) delete Rorgt selectively in gd T cells in offspring of allergen-exposed fathers, and 2) adoptively transfer lung Rorgt+ gd T cell populations isolated from offspring of control or allergen-exposed fathers into the lungs of control mice. The complete asthma phenotype will be assessed to determine if pulmonary gd T cells are necessary and/or sufficient mediators of paternal allergen-exposure-mediated protection from offspring asthma. Aim 2: Construct the gene regulatory networks (GRNs) governing asthma-protective lung gd T cells. To this end, lung gd T cells from offspring of control and allergen-exposed fathers will be isolated prior to, and after allergen sensitization, and profiled using scRNA-seq and scATAC-seq for GRN construction. The GRN will identify how TFs utilize enhancers and orchestrate gene expression patterns correlated with asthma protection. We will determine whether the asthma- protective role of gd T cells is due to changes in subset abundances and/or altered functionality. An understanding of the cellular and molecular mec...