Hypertension is world’s largest contributing factor to disease and mortality. Diets high in saturated fat are increasingly linked to the development of hypertension, although the patho-physiological mechanisms responsible for the development of hypertension remain poorly understood. This proposal examines a novel molecular mechanism by which a chronic high saturated fat diet (HFD) activates the immune system to promote increases in adiposity and blood pressure (BP). Moreover, although young women are typically protected from hypertension relative to age-matched men, epidemiological studies suggest that the cardiovascular protection typically associated with young women is compromised by chronic consumption of a diet high in saturated fat. Our study will examine the novel central hypothesis that a chronic HFD causes a greater increase in BP in females via sex-specific activation and recruitment of immune cells. Studies will further test the hypothesis that greater NLRP3 activation in females drives enhanced immune cell activation with a chronic HFD. Adipose tissue is a critical intermediary between immune cell activation and hypertension and the NLRP3 inflammasome contributes to adipose tissue inflammation. Proposed experiments will expand our understanding of how a HFD promotes the development of hypertension in adult males and females by testing two specific aims. Aim 1 will test the hypothesis that greater NLRP3 activation with chronic HFD in females results in a more pro-inflammatory immune cell profile compared to males resulting in greater increases in BP. Experiments will measure the impact of HFD on NLRP3 expression and activation in male and female rats, assess the contribution of NLRP3 to HFD- induced increases in inflammation and hypertension using novel genetic knockouts, and begin to translate our findings by measuring NLRP3 in isolated peripheral blood monocytes in a cohort of Black and White, lean and obese men and women. Aim 2 will test the hypothesis that immune cells promote greater adipose tissue expansion in females with a HFD. Experiments will determine if the impact of HFD on macrophage and T cell transcriptional profiles and adipose tissue is sex-specific, assess the contributions of NLRP3 and T cells to HFD- induced alterations in adipose tissue using novel genetic models, use adoptive transfer studies and adipose tissue transplants to assess the relative contributions of T cells vs. adipose tissue on HFD-induced adipocyte expansion, inflammation and hypertension, and determining if gender impacts the relationships between BMI, BP, inflammation and CVD risk in a human subject cohort. Therapies targeting the pathophysiological cause of hypertension will undoubtedly improve BP control rates and prevent premature death from CVD in both sexes. Results of this work will transform our understanding of immune mechanisms in HFD-induced hypertension by utilizing novel approaches, revealing new paradigms, and providing insight with t...