ABSTRACT The goal of this proposal is to improve our understanding of the factors that drive clonal hematopoiesis (CH) evolution to prevent CH-related adverse outcomes and promote healthy aging. CH is common with aging. Most mutations are present in a small proportion of hematopoietic stem cells (HSCs). Yet in some individuals, the proportion of mutated HSCs will expand resulting in dysregulation of hematopoiesis and immune cell function. CH is associated with several age-related diseases, including two leading causes of death and disability among the elderly: cardiovascular disease (CVD) and Alzheimer's disease (AD). The mechanisms driving CH evolution are largely undefined. This is due, in part, to a lack of longitudinal studies of CH alongside comprehensive risk factor assessment. CH alters the balance of immune cell pro- and anti-inflammatory signaling. This is thought to underlie many CH-disease associations. Pre-clinical models suggest that chronic inflammation promotes CH fitness, but this has yet to be established in human studies. Chronic inflammation, as driven by an unhealthy lifestyle, has also been shown to increase the risk of many age-related diseases. Unhealthy lifestyle is prevalent throughout the United States and contributes to up to 60% of premature deaths. There are conflicting results regarding the association between CH and an unhealthy lifestyle. This may be due to measurement error driven by imprecise, one-time assessments of lifestyle risk factors. Longitudinal studies of both CH and lifestyle risk factors over the life-course of an individual are needed. Here we seek to characterize how inherited and lifestyle risk factors influence CH fitness and to identify the central pathways that determine long-term CH evolutionary trajectories and disease progression. Through our preliminary work, we jointly characterized CH and plasma proteomic profiles of 46,237 individuals in the UK Biobank (UKBB). We identified 79 proteins significantly associated with CH, the majority of which are known immune regulators. A subset of these proteins also predicts risk of CVD and AD development. Our central hypothesis is that inherited, and lifestyle risk factors impact CH evolution through immune dysregulation and that this in turn determines the development of age-related outcomes. We will leverage existing data from large-scale biobanks alongside comprehensive CH profiling in unique cohorts with repeated risk factor and biologic measurements. This includes two prospective cohorts with >30 years of follow-up: 1) The Health Professionals Follow-up Study, with rich assessment of lifestyle risk factors alongside centrally adjudicated CVD outcomes and 2) The Knight Alzheimer's Disease Research Center studies with centrally adjudicated cognition and AD outcomes alongside serial CSF sampling. The specific aims are: (1) determine the impact of lifestyle and inherited risk factors on CH evolution, (2) determine the pathways that mediate CH evolution ...