Role of IL21 in HIV Infection

描述（由申请人提供）：白细胞介素-21 （IL-21）是一种I型细胞因子，已被证明可以调节T、B、NK和骨髓细胞的功能，特别是在小鼠模型中。IL-21受体（IL-21R）与IL-2受体密切相关，能够通过其与共同γ链的二聚化（3c）传导信号。我们对HIV阳性受试者外周血淋巴细胞的初步研究揭示了IL-21R信号传导的两个有趣方面。首先，它选择性地上调CD8 T细胞中细胞溶解分子穿孔素的表达，而不诱导增殖，不像其他细胞因子通过3c受体发出信号。其次，病毒毒HAART治疗的HIV感染者的细胞对IL-21的反应比健康的HIV未感染志愿者的细胞更敏感。本研究将研究IL-21在HIV+和HIV阴性个体中对穿孔素上调的分子机制，以及IL-21独特的缺乏诱导增殖信号的机制。此外，它将验证IL-21的穿孔素增强能力将增强CD8 T细胞和自然杀伤（NK）细胞对恒河猴SIV的细胞溶解活性的假设。我们的第一个目的是扩展之前的观察，研究IL-21在病毒血症和病毒血症HIV感染患者的T细胞和NK细胞上的活性，研究T细胞、NK细胞上穿孔素和IL- 21r的表达、CD4 T细胞合成IL-21和血浆IL-21水平。我们的第二个目标是在恒河猴体内进行研究，以确定IL-21的安全剂量和生物活性，验证它是否能增强抗病毒免疫反应，并确定其对病毒复制的影响。为此目的，我们将与博士合作。埃默里大学的Francois Villinger对健康的未感染猴子进行了研究，国家癌症研究所的genveffa Franchini对长期感染猴免疫缺陷病毒（SIV）的猴子进行了研究。我们的第三个目标是详细研究IL-21/IL-21R信号导致穿孔素上调而不引起增殖的分子机制。Stat5与Stat3的作用以及hiv相关免疫激活在促进IL-21信号传导中的作用将被研究。这些研究将指导IL-21用于HIV感染免疫治疗的未来发展。在使用强效抗逆转录病毒药物治疗艾滋病毒感染患者方面取得了很大进展，但长期治疗存在药物相关并发症的风险。还有一些患者尽管使用了强效药物，但仍未能控制病毒。该项目正在研究白细胞介素-21 (IL-21)，这是一种由宿主自然产生的生物蛋白（细胞因子），被发现可以增加穿孔素，穿孔素是杀手细胞用来杀死病毒感染细胞的分子。这些研究将研究IL-21作用的分子基础，并通过在猴子体内注射IL-21来测试其活性。如果结果是有希望的，IL-21可能会被开发成一种制剂，既可以增强对艾滋病病毒的免疫反应，也可以与疫苗一起使用，以提高疫苗活性。

DESCRIPTION (provided by applicant): Interleukin-21 (IL-21) is a type I cytokine that has been shown to modulate functions of T, B, NK, and myeloid cells, particularly in murine models. The IL-21 receptor (IL-21R) is closely related to the IL-2 receptor and is capable of transducing signals through its dimerization with the common gamma chain (3c). Our initial studies in peripheral blood lymphocytes of HIV+ subjects revealed two intriguing aspects of IL-21R signaling. First, it selectively upregulates expression of the cytolytic molecule perforin in CD8 T cells in vitro without inducing proliferation, unlike other cytokines that signal through 3c receptors. Second, the cells of aviremic HAART treated HIV infected persons were more responsive to IL-21 than cells of healthy HIV-uninfected volunteers. The present proposal will examine the molecular mechanisms involved in perforin upregulation by IL-21 in HIV+ versus HIV negative individuals and in its unique absence of inducing proliferative signals. Furthermore it will test the hypothesis that the perforin enhancing capabilities of IL-21 will augment cytolytic activity of CD8 T cells and Natural Killer (NK) cells against SIV in rhesus macaques. Our first aim is to extend previous observations and investigate the activity of IL-21 on T cells and NK cells of viremic and aviremic HIV infected patients for expression of perforin and IL-21R on T cells, NK cells, synthesis of IL- 21 by CD4 T cells and plasma IL-21 levels. In our 2nd aim in vivo studies in rhesus macaques are proposed to identify the dose at which IL-21 is safe and biologically active, to verify that it potentiates antiviral immune responses and to establish its effect on viral replication. For this aim we will be collaborating with Drs. Francois Villinger at Emory University for studies in healthy uninfected monkeys and Genoveffa Franchini at the National Cancer Institute for studies in monkeys chronically infected with the Simian immune deficiency virus (SIV). Our 3rd aim is to examine in detail the molecular mechanism of IL-21/IL-21R signaling resulting in perforin upregulation without causing proliferation. The role of Stat5 versus Stat3 and role of HIV-associated immune activation in promoting IL-21 signaling will be examined. These studies will guide future development of IL-21 for immunotherapy in HIV infection. Much progress has been made in the treatment of HIV-infected patients with potent antiretroviral drugs, but long term therapy carries the risk of drug related complications. There are also some patients who fail to control the virus despite treatment with potent drugs. This project is investigating interleukin-21 (IL-21), a biologic protein (cytokine) made naturally by the host which was found to increase perforin, a molecule used by killer cells to kill virally infected cells. The proposed studies will investigate the molecular basis of the action of IL-21 and test it for activity by infusing it in monkeys. If the results are promising, IL-21 could potentially be developed as an agent that could either augment immune responses against the AIDS virus or be used with vaccines to boost vaccine activity.