Inhibition of HIV-1 in Sickle Cell Disease

Howard University, Washington DC

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Abstract

DESCRIPTION (provided by applicant): Sickle-cell disease (SCD) is a hereditary disorder that affects approximately 100,000 people in the USA, primarily of African descent. Single E6V mutation in b-globin gene leads to the production of hemoglobin S (HbS) and development of chronic hemolytic anemia. Our recent analysis of a national hospital discharge survey showed an association of SCD with lower frequency of HIV-1 diagnosis (odds ratio 0.33) suggesting that SCD might offer a protection from HIV-1. We hypothesize that hemolytic anemia in SCD leads to inhibition of HIV-1 transcription through the activation of heme-, iron and oxygen-dependent pathways. Heme induces transcription of iron regulatory genes in macrophages, including heme oxygenase-1 (HO-1), ferritin and iron export protein, ferroportin leading to the increased iron export and reduction of cellular iron. In SCD, expression of HO-1 is increased whereas expression of hepcidin that regulates internalization and degradation of ferroportin is decreased (and also our preliminary data). Induction of HO-1 by heme inhibits HIV-1 infection in macrophages and T-cells in vitro and in HIV-1 infected humanized mice. We have previously shown that HIV-1 transcription is inhibited by iron chelators or ferroportin. Iron chelators inhibi cellular activities of CDK2 and CDK9, both critical for HIV-1 transcription. Our recent findings demonstrate that CDK2 directly phosphorylates CDK9's Ser90 resulting in the activation of HIV-1 transcription. We, therefore, hypothesize that increased blood heme concentration, ischemia and decreased hepcidin will elevate levels and activity of HO-1 and ferroportin, reduce cellular iron and upregulate HIF-1 pathway leading to the induction of Egr-1, p21 and inhibition of CDK2 and CDK9. Upregulation of this protein network will lead to the inhibition HIV-1 transcription and viral replication in SCD condition. In Specific Aim 1, we will analyze HIV-1 inhibition in SCD and SCD trait. In Specific Aim 2, we will analyze molecular mechanisms of HIV-1 inhibition in SCD and SCD trait. In Specific Aim 3, we will analyze novel inhibitors HO-1, ferroportin and hepcidin pathways in vivo. Collectively, our proposed research is designed to elucidate the molecular mechanisms of HIV-1 inhibition in the settings of SCD and SCD trait. Our studies will uncover novel mechanisms of HIV-1 regulation by heme, ferroportin, hepcidin, and iron. Our proposed studies are significant because they may lead to novel therapeutics, such as the use of hemin and iron chelators.