The long-term goal of this research program is to characterize the antecedents and mediators of morbid long-term outcomes in patients with sepsis. Despite successful early management, sepsis is a disease with a high incidence of chronic critical illness (CCI - intensive care unit stay ≥ 14 days with organ dysfunction) and morbid long-term outcomes (functional dependence or death at 1 year), which occur frequently in early survivors. Both the rapid identification of patients at risk for morbid outcomes and the development of novel therapies are crucial for improving outcomes after sepsis. High density lipoprotein (HDL) defends against sepsis-associated organ injury by: 1) neutralizing bacterial endotoxin, 2) modulating innate cellular immunity and preventing release of inflammatory cytokines, and 3) preventing endothelial cell activation and dysfunction. However, HDL can become dysfunctional (Dys-HDL) in the setting of inflammation, losing protective functions and becoming pro-inflammatory. Our preliminary results demonstrate that Dys-HDL is present in early sepsis and that persistent Dys-HDL elevation (first 48 hours) is associated with adverse outcomes (death, hospice or nursing home care). The overall goal of this proposal is to investigate and fully characterize the role of Dys-HDL in a diverse population of patients with both CA and HA-sepsis. The central hypothesis of this study is that structural and functional changes in HDL during sepsis are associated with the persistent presence of Dys-HDL as well as the inflammation and endothelial dysfunction that lead to acute organ dysfunction, CCI, and morbid long-term outcomes. To test this, we will enroll 160 patients in a two-site, prospective, longitudinal, cohort study.