Inhibition of HIV-1 in Sickle Cell Disease

描述(申请人提供)：镰状细胞病(SCD)是一种遗传性疾病，在美国大约有10万人受到影响，主要是非洲裔。B-珠蛋白基因单一的E6V突变会导致产生血红蛋白S(HBs)，从而导致慢性溶血性贫血的发生。我们最近对全国医院出院调查的分析表明，SCD与较低的HIV-1诊断频率(优势比0.33)有关，这表明SCD可能提供了对HIV-1的保护。我们假设，SCD中的溶血性贫血通过激活血红素、铁和氧依赖的途径抑制HIV-1的转录。血红素诱导巨噬细胞铁调节基因的转录，包括血红素加氧酶-1(HO-1)、铁蛋白和铁出口蛋白，铁蛋白导致铁出口增加和细胞铁减少。在SCD中，HO-1的表达增加，而调节铁蛋白内化和降解的海普西丁的表达减少(我们的初步数据也是如此)。血红素诱导HO-1在体外抑制巨噬细胞和T细胞中的HIV-1感染以及在HIV-1感染的人源化小鼠中。我们之前已经证明，HIV-1的转录被铁络合剂或铁蛋白抑制。铁络合剂抑制对HIV-1转录至关重要的CDK2和CDK9的细胞活性。我们最近的发现表明，CDK2直接磷酸化CDK9的S Ser90，导致HIV-1转录的激活。因此，我们假设，增加血液中的血红素浓度、缺血和降低海普西丁会提高HO-1和铁蛋白的水平和活性，降低细胞内的铁含量，上调HIF-1通路，导致Egr-1、p21的诱导和CDK2、CDK9的抑制。在SCD条件下，该蛋白网络的上调将导致HIV-1转录和病毒复制的抑制。在具体目标1中，我们将分析SCD和SCD特性对HIV-1的抑制作用。在具体目标2中，我们将分析HIV-1抑制SCD的分子机制和SCD的特点。在具体目标3中，我们将在体内分析新的抑制剂HO-1、铁蛋白和海普西丁途径。总之，我们提出的研究旨在阐明在SCD和SCD特征背景下抑制HIV-1的分子机制。我们的研究将揭示血红素、铁蛋白、海普西丁和铁调节HIV-1的新机制。我们提出的研究具有重要意义，因为它们可能导致新的治疗方法，如使用氯化血红素和铁络合剂。

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.