PROJECT SUMMARY/ABSTRACT OF PARENT GRANT Antiretroviral therapy has transformed HIV infection into a chronic disease and the population living with HIV infection (PLWH) is aging. PLWH are twice as likely to develop cardiovascular disease (CVD) and in the past two decades, the global burden of HIV-associated CVD has tripled. Chronic inflammation and immune activation persist in the setting of treated HIV and are strongly predictive of CVD events and mortality. In the general population, acquired mutations in hematopoietic cells (clonal hematopoiesis of indeterminate potential, CHIP) increase with age and are associated with an increased risk for CVD and premature MI independent of age or other traditional risk factors. Clonally expanded blood cells contain large scale mosaic chromosomal alterations (mCAs) which also increase with age and are associated with risk for infectious disease, and mortality but have not been studied in HIV. While the underlying mechanisms for excess risk of CVD among people with CHIP mutations is not clear, recent studies suggest the NLRP3/IL-1β/IL-6 pathways play a role. This is critically important because these pathways represent targets for immunomodulatory therapy and underlying mechanisms by which PLWH have an excess risk of CVD. Our group has demonstrated that HIV is associated with a 2-fold increase in CHIP and have a high prevalence of mCA but the relationship between CHIP/mCA and CVD risk in PLWH has not been evaluated; furthermore, the underlying mechanism for increased CHIP/mCA among PLWH remains unknown. We plan to study the existing Veterans Aging Cohort Study Biomarkers Cohort (VACS BC) which is a prospective observational cohort of 1525 HIV+ and 853 HIV- Veterans with extensive adjudicated outcomes, existing data on biomarkers of inflammation, and immune function. An additional 1000 PLWH in the Center for AIDS Research Network of integrated Clinical Systems (CNICS) and 1002 PLWH in the Department of Defense (DoD) cohort will also be studied. We hypothesize that HIV is a fertile substrate for development of CHIP mutations and mCAs and that CHIP activates inflammation to drive HIV-associated atherosclerosis. We propose the following Specific Aims: Aim 1: To determine if CHIP mutations and mCAs are more prevalent in PLWH vs. uninfected individuals (Aim 1A). and to determine whether the presence of CHIP mutations/mCAs are associated with an increased risk of CVD and mortality events in PLWH (Aim 1B); Aim 2: To elucidate the mechanism underlying CHIP/mCA in HIV by evaluation of markers of inflammation/immune activation, epigenomics, and HIV viral reservoir size; Aim 3: To investigate whether clonal populations of immune cells from PLWH with CHIP display altered gene regulatory programs that increase pathologic activation of specific immune cell types. If our hypotheses are correct, CHIP/mCAs may serve as a novel biomarker for CVD risk among people aging with HIV infection and help identify those PLWH who may be...