Understanding the Role of the Host Response in HIVSIV Infection

方法1：人类免疫缺陷病毒(HIV)感染与免疫激活、CD4(+)-T细胞丢失和免疫功能进行性下降有关。抗逆转录病毒疗法(ART)只能部分逆转HIV相关的免疫功能障碍，这表明可能需要针对免疫激活和改善病毒特异性免疫反应的方法。我们对感染致病猴免疫缺陷病毒SIV(Mac251)的恒河猴进行了一项临床前研究，并用ART进行了治疗。我们测试了联合细胞毒性T淋巴细胞相关抗原4(CTLA-4)免疫接种和吲哚胺2，3-双加氧酶(IDO)抑制剂1-甲基-D-色氨酸(D-1MT)治疗是否降低了免疫活性和提高了疫苗效力。这种治疗没有增强疫苗的免疫原性；相反，它显著增加了与ART相关的毒性，导致所有接受治疗的动物死于急性胰腺炎和高血糖昏迷。暴发性糖尿病的发病与胰腺严重的淋巴细胞浸润和朗格汉斯胰岛的完全丧失有关。因此，当考虑在抗逆转录病毒治疗期间针对免疫激活的方法时应谨慎。方法2：我们先前已经证明，白介素21，一种多效性Cα链信号细胞因子，在体外诱导慢性HIV感染者CD8T细胞和NK细胞中细胞毒分子颗粒酶B(GRB)和穿孔素的表达。在这项初步研究中，4只慢性SIV感染的晚期恒河猴(RM)分两次静脉注射重组IL-21，50微克/公斤，间隔7天，然后皮下注射一次，100微克/公斤，在第二次注射后23天。三只动物作为对照。不同剂量IL-21作用后，外周血(PB)、外周血和肠系膜淋巴结(LN)细胞、外周血记忆细胞、效应CD4T细胞和NK细胞中GRB和穿孔素的表达频率和平均荧光强度均增加。SIV-Gag特异性CD107a(+)干扰素-α(+)CD8T细胞的频率在PB和LN分别增加了3.8倍和1.8倍。此外，IL-21治疗后外周血CD27(+)记忆B细胞数增加2倍，血清SIV抗体水平显著升高。T细胞活化、T细胞增殖、血浆病毒载量等指标均未见明显变化。因此，给慢性SIV感染的病毒感染动物注射IL-21是安全的，耐受性良好，可以增强T细胞和NK细胞的细胞毒作用，促进B细胞分化，SIV抗体效价增加，而细胞活性没有明显增加。有必要进行进一步的研究，以阐明在SIV/HIV感染和SIV/HIV疫苗设计中使用IL-21的效果和潜在益处。

Approach 1: Human immunodeficiency virus (HIV) infection is associated with immune activation, CD4(+)-T-cell loss, and a progressive decline of immune functions. Antiretroviral therapy (ART) only partially reverses HIV-associated immune dysfunction, suggesting that approaches that target immune activation and improve virus-specific immune responses may be needed. We performed a preclinical study in rhesus macaques infected with the pathogenic simian immunodeficiency virus SIV(mac251) and treated with ART. We tested whether vaccination administered together with cytotoxic-T-lymphocyte-associated antigen 4 (CTLA-4) blockade and treatment with the indoleamine 2,3-dioxygenase (IDO) inhibitor 1-methyl-D-tryptophan (D-1mT), decreased immune activation and improved vaccine efficacy. The treatment did not augment vaccine immunogenicity; rather, it dramatically increased ART-related toxicity, causing all treated animals to succumb to acute pancreatitis and hyperglycemic coma. The onset of fulminant diabetes was associated with severe lymphocyte infiltration of the pancreas and complete loss of the islets of Langerhans. Thus, caution should be used when considering approaches aimed at targeting immune activation during ART.Approach 2: We have previously shown that interleukin-21, a pleiotropic C alpha-chain signaling cytokine, induces the expression of the cytotoxic molecules granzyme B (GrB) and perforin in vitro in CD8 T cells and NK cells of chronically HIV infected individuals. In this pilot study, four chronically SIV infected rhesus macaques (RM) in late-stage disease were given two doses of recombinant IL-21, 50 mcg/kg, intravenously 7 days apart, followed by one subcutaneous dose, 100 mcg/kg, 23 days after the second dose. Three animals served as controls. After each dose of IL-21, increases were noted in frequency and mean fluorescence intensity of GrB and perforin expression in memory and effector subsets of CD8 T cells in peripheral blood (PB), in peripheral and mesenteric lymph node (LN) cells, in PB memory and effector CD4 T cells and in NK cells. Frequencies of SIV-gag specific CD107a(+)IFN-alpha(+) CD8 T cells increased 3.8-fold in PB and 1.8-fold in LN. In addition, PB CD27(+) memory B cells were 2-fold higher and serum SIV antibodies increased significantly after IL-21 administration. No changes were observed in markers of T cell activation, T cell proliferation or plasma virus load. Thus, administration of IL-21 to chronically SIV infected viremic animals was safe, well tolerated and could augment the cytotoxic potential of T cells and NK cells, promote B cell differentiation with increases in SIV antibody titers without discernable increase in cellular activation. Further studies are warranted to elucidate the effects and potential benefit of IL-21 administration in the context of SIV/HIV infection and in SIV/HIV vaccine design.