TAT and AIDS: As inflammatory cytokines are strong inducers of endothelial cell activation and dysfunction, this evidence indicates a role for extracellular Tat in the pathogenesis of HIV comorbidities (AIDS-associated and non-AIDS related) that goes beyond its role in the virus life cycle and is characterized by the many ways extracellular Tat affects the physiology of the vascular system, contributing to the onset of endothelial cell dysfunction and progression toward virtually all HIV-related comorbidities.