Role of IL21 in HIV Infection

描述(申请人提供)：白介素21(IL-21)是一种I型细胞因子，已被证明可调节T、B、NK和髓系细胞的功能，特别是在小鼠模型中。IL-21受体(IL-21R)与IL-2受体关系密切，能够通过与共同的伽马链(3c)的二聚化来传递信号。我们最初对HIV+受试者的外周血淋巴细胞的研究揭示了IL-21R信号的两个有趣的方面。首先，与其他通过3c受体传递信号的细胞因子不同，它在体外选择性地上调CD8T细胞中细胞溶解分子穿孔素的表达，而不会诱导增殖。其次，接受HAART治疗的HIV感染者的细胞比未感染HIV的健康志愿者的细胞对IL-21的反应更强。目前的建议将研究IL-21在HIV+和HIV阴性个体中上调穿孔素的分子机制，以及在其独特的缺乏诱导增殖信号的情况下。此外，它还将验证穿孔素增强IL-21的能力将增强CD8 T细胞和自然杀伤细胞(NK)对SIV的杀伤活性的假设。本研究的第一个目的是进一步研究HIV感染者T细胞和NK细胞上IL-21的活性，包括T细胞、NK细胞表面穿孔素和IL-21R的表达、CD4T细胞合成IL-21和血浆IL-21水平。在我们的第二个目标中，我们建议对恒河猴进行体内研究，以确定IL-21的安全和生物活性的剂量，验证它是否增强了抗病毒免疫反应，并确定其对病毒复制的影响。为此，我们将与埃默里大学的Francois Villinger博士合作研究健康的未感染猴子，并与国家癌症研究所的Genoveffa Franchini合作研究慢性感染猿猴免疫缺陷病毒(SIV)的猴子。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细胞增殖的分子机制。将检验Stat5和STAT3的作用，以及HIV相关免疫激活在促进IL-21信号转导中的作用。这些研究将指导未来IL-21用于HIV感染的免疫治疗的发展。在用有效的抗逆转录病毒药物治疗艾滋病毒感染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。也有一些患者尽管接受了强效药物的治疗，但仍未能控制病毒。该项目正在研究白介素21(IL-21)，这是一种由宿主自然产生的生物蛋白质(细胞因子)，被发现可以增加穿孔素，这是一种被杀伤细胞用来杀死受病毒感染的细胞的分子。这项拟议的研究将调查IL-21作用的分子基础，并通过将其注入猴子体内来测试其活性。如果结果很有希望，IL-21可能会被开发为一种试剂，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.