PROJECT SUMMARY/ABSTRACT Childhood exposure to adverse social determinants of health (SDoH) is highly prevalent in contemporary youth and is linked in a dose-dependent manner with adult cardiovascular disease (CVD) rates. Metabolic and immune dysfunction are thought to be involved, but many questions remain as to how SDoH get `under the skin' to activate biological pathways leading to CVD. The human microbiome may be a key mediator of SDoH-CVD associations and related disparities, but research in this area is sparse. Small studies indicate that the gut microbiome varies across socioeconomic levels and can be modified by housing environments, social connectedness, and psychosocial stress. Separately, experimental data demonstrate causal roles for the microbiome in host immune function, metabolism, and atherosclerosis. However, lack of comprehensive data on SDoH, the microbiome, and CVD phenotypes in disadvantaged populations is a critical barrier to understanding potential links. Our long-term goal is to develop strategies to reduce the burden of SDoH-related CVD in disadvantaged populations. The objective of the current proposal is to establish a biorepository and generate pilot and feasibility data for a near-term R01 proposal in which we will aim to comprehensively assess associations between early-life SDoH, the gut microbiome, and CVD risk indicators in young adults and further examine causal mechanisms in a gnotobiotic mouse model. We propose an ancillary study of >1000 young adults in the Fragile Families Study (FFS). FFS enrolled newborns in large US cities from 1998-2000, with oversampling of infants born to unmarried, racial/ethnic minority, immigrant, and low-income parents. Comprehensive, detailed SDoH, psychological, and behavioral data have been collected at birth and ages 1, 3, 5, 9, and 15 years, as well as genotype and genome-wide DNA methylation at ages 9 and 15 years. The NHLBI- funded (R01 HL149869) examination at age 22 years will include similar measures plus detailed CVD risk factor data and state-of-the-art carotid artery imaging to detect early atherosclerosis. For the current R03, we propose to establish a gut microbiome repository from FFS participants, including stool DNA for shotgun metagenomic analysis and fresh stool samples for gnotobiotic experiments, and to generate preliminary data through the following Specific Aims: (1) Identify associations of early-life SDoH with the young-adult gut microbiota, and (2) Identify gut microbiota variables associated with young-adult subclinical CVD, CVD risk factors, and epigenetic age, in a subset of N=95 FFS participants, to inform design of the subsequent R01 proposal. The biospecimens and data resulting from the proposed project will directly support successful transition of the PI to independent funding, building on her K23-funded study of the gut microbiome as a contributor to CVD risk in early life. The science proposed in the subsequent R01 will substantially advance our...