Induction of HIF-1α by HIV-1 Infection in CD4+ T Cells Promotes Viral Replication and Drives Extracellular Vesicle-Mediated Inflammation.

Chronic immune activation and inflammation are hallmarks of HIV-1 infection and a major cause of serious non-AIDS events in HIV-1-infected individuals on antiretroviral treatment (ART). Herein, we show that cytosolic double-stranded DNA (dsDNA) generated in infected CD4+ T cells during the HIV-1 replication cycle promotes the mitochondrial reactive oxygen species (ROS)-dependent stabilization of the transcription factor hypoxia-inducible factor 1α (HIF-1α), which in turn, enhances viral replication. Furthermore, we show that induction of HIF-1α promotes the release of extracellular vesicles (EVs). These EVs foster inflammation by inducing the secretion of gamma interferon by bystander CD4+ T cells and secretion of interleukin 6 (IL-6) and IL-1ß by bystander macrophages through an HIF-1α-dependent pathway. Remarkably, EVs obtained from plasma samples from HIV-1-infected individuals also induced HIF-1α activity and inflammation. Overall, this study demonstrates that HIF-1α plays a crucial role in HIV-1 pathogenesis by promoting viral replication and the release of EVs that orchestrate lymphocyte- and macrophage-mediated inflammatory responses.IMPORTANCE Human immunodeficiency virus type 1 (HIV-1) is a very important global pathogen that preferentially targets CD4+ T cells and causes acquired immunodeficiency syndrome (AIDS) if left untreated. Although antiretroviral treatment efficiently suppresses viremia, markers of immune activation and inflammation remain higher in HIV-1-infected patients than in uninfected individuals. The hypoxia-inducible factor 1α (HIF-1α) is a transcription factor that plays a fundamental role in coordinating cellular metabolism and function. Here we show that HIV-1 infection induces HIF-1α activity and that this transcription factor upholds HIV-1 replication. Moreover, we demonstrate that HIF-1α plays a key role in HIV-1-associated inflammation by promoting the release of extracellular vesicles which, in turn, trigger the secretion of inflammatory mediators by noninfected bystander lymphocytes and macrophages. In summary, we identify that the coordinated actions of HIF-1α and extracellular vesicles promote viral replication and inflammation, thus contributing to HIV-1 pathogenesis.

Monocytes as regulators of inflammation and HIV-related comorbidities during cART.

Combined antiretroviral therapy (cART) extends the lifespan and the quality of life for HIV-infected persons but does not completely eliminate chronic immune activation and inflammation. The low level of chronic immune activation persisting during cART-treated HIV infection is associated with the development of diseases which usually occur in the elderly. Although T-cell activation has been extensively examined in the context of cART-treated HIV infection, monocyte activation is only beginning to be recognized as an important source of inflammation in this context. Here we examine markers and sources of monocyte activation during cART-treated HIV infection and discuss the role of monocytes during cardiovascular disease, HIV-associated neurocognitive disorder, and innate immune aging.