Blood Markers of Inflammation, Blood Clotting and Blood Vessel Function in HIV-infected Adults

D-dimer, a fibrin degradation product generated as a result of plasmin mediated clot dissolution processes, is an indicator of recent clot formation and subsequent fibrinolysis. Analysis of D-dimer concentration is employed in the diagnosis of deep vein thrombosis, pulmonary embolism, and disseminated intravascular coagulation. More recently, D-dimer levels have been correlated with atherosclerotic cardiovascular disease. In a recent case-control study of biomarkers for cardiovascular disease in human immunodeficiency virus (HIV)-infected adults, baseline D-dimer levels strongly correlated with all-cause mortality. Notably, the association between baseline D-dimer levels and death due to cardiovascular disease was less significant. At present, the pathophysiology underlying the association of elevated D-dimer concentrations with mortality in HIV is not understood. This study seeks to identify possible mechanisms underlying D-dimer elevations in HIV-infected adults by investigating a number of pathways that may be associated with the elevations using biomarkers of inflammation, hemostasis, thrombosis, platelet function, lipid metabolism, and additional indicators of endothelial function. Further elucidation of plausible pathways contributing to D-dimer elevation could, ultimately, lead to trials of risk-reducing interventions for patients with an elevated D-dimer level. This study, an exploratory, cross-sectional study of up to 350 subjects, seeks to prospectively collect data on D-dimer and related biomarkers in HIV-infected adults. Initially, the study will recruit HIV-infected adults with HIV viremia who are not taking antiretroviral therapy (ART) and compare their clinical histories and biomarker findings with those from (1) a group of HIV-infected adults with controlled HIV viremia who are receiving ART, and with those from (2) a control group of HIV-negative healthy subjects. Additionally, to study the impact of persistent immune activation and inflammation on immune responses to ART, a cohort of HIV-infected adults with poor CD4+ cell recovery despite effective ART, and to better understand the mechanisms that contribute to impaired immunologic recovery, a cohort of HIV-infected adults with poor CD4+ cell recovery despite effective ART will be enrolled (immunologic non-responder cohort) and for comparison, a control group with similar nadir CD4 counts but with good CD4+ cell recovery on ART. The study requires 2 visits for screening, history and physical examination, and phlebotomy. A wide array of research assays investigating different aspects of inflammation, coagulation, and endothelial function will be completed. Samples will be stored for future investigation.