Preventive and therapeutic T cell vaccines to mitigate HIV-1 replication; Preven

直接证据表明，抗体和CD8+ T细胞都有助于限制猴免疫缺陷病毒（SIV）的复制。然而，在CD4+ T细胞的情况下，很难确定它们的作用，因为它们也是病毒感染的目标。猕猴的SIVmac251感染是评估这些问题的一个很好的模型。由于T细胞疫苗的预防性接种改善了病毒攻击后的病毒学结果，我们探索了在接受抗逆转录病毒治疗（ART）的已感染猕猴中增强病毒特异性免疫反应的策略。我们证明CTLA-4阻断降低了sivmac251感染猕猴组织中tgf - β、IDO和病毒RNA的表达。调节性T细胞（Treg）是CD25+CD4+ T细胞的一个亚群，其组成性表达高水平的细胞毒性T淋巴细胞抗原-4 （CTLA-4）并抑制T细胞活化和效应功能。感染HIV-1的个体和感染猴免疫缺陷病毒（SIVmac251）的猕猴的组织中Treg细胞增加。在HIV-1感染中，Treg细胞可以发挥不同的作用：它们可以通过降低免疫激活来限制病毒复制，或者通过抑制病毒特异性免疫反应来增加病毒复制。因此，阻断Treg在HIV/SIV中的功能的结果应该进行实证检验。我们证明了CD25+ T细胞在siv感染猕猴的血液和淋巴结培养的T细胞中抑制病毒特异性T细胞反应。我们利用抗CTLA-4人抗体MDX-010研究了阻断CTLA-4对接受抗逆转录病毒治疗（ART）的siv感染猕猴的影响。CTLA-4阻断降低了组织中色氨酸消耗酶IDO的表达和抑制性细胞因子转化生长因子- β (tgf - β)的水平。CTLA-4阻断与淋巴结病毒RNA水平下降和siv特异性CD4+和CD8+ T细胞效应功能增加有关。因此，削弱SIV感染猕猴的Treg功能不会产生有害的病毒学效应，可能为补充ART和治疗性疫苗接种治疗HIV-1感染提供有价值的方法。急性HIV/SIV感染导致淋巴细胞室严重的CD4+ T细胞耗损。在感染的慢性期，CD4+ T细胞数量在血液中反弹，但在肠相关淋巴组织（GALT）中仍然很低，即使抗逆转录病毒疗法抑制了病毒复制。因此，重新填充淋巴细胞室的策略可能会改善HIV/SIV感染的临床结果。白细胞介素(IL)-7是维持T细胞稳态增殖的关键细胞因子。在HIV/SIV感染中，IL-7表达增加，可能补偿T细胞的损失，这表明生理上给药IL-7可以提供额外的益处。然而，T细胞对IL-7的反应能力取决于不同体区室T细胞中IL-7受体（IL-7R）的表达水平。我们研究了CD4+ T细胞不同程度耗损的健康猕猴和siv感染猕猴血液、脾脏、肠道和泌尿生殖道中IL-7R+ T细胞的比例。我们发现siv感染猕猴的CD4+和CD8+ T细胞亚群中表达IL-7R的T细胞百分比明显低于健康动物，这种下降与CD4+ T细胞数量直接相关。重要的是，血液中表达IL-7R的CD4+和CD8+ T细胞的比例与组织中发现的相似。siv特异性CD8+ T细胞中的IL-7R+ T细胞在病毒毒猕猴的大多数组织中含量最低，可能反映了效应细胞的持续抗原刺激。在sivmac251感染的猕猴中，我们发现IL-15消除了疫苗引起的病毒水平下降。HIV感染中CD4+ T细胞的丢失和CD8+ T细胞功能的损害提示，用IL-7和IL-15进行药物治疗可能是有益的，这些细胞因子可以增加T细胞的稳态增殖并改善效应功能。然而，这些细胞因子也可能对HIV-1感染个体产生不利影响，因为这两种细胞因子在体外都会增加HIV的复制。我们评估了IL-7和IL-15处理对sivmac251感染的猕猴（Macaca mulatta）病毒复制和痘病毒活疫苗免疫原性的影响。两种细胞因子都不能增加疫苗扩增的CD4+或CD8+记忆T细胞的频率、克隆募集到siv特异性CD8+ T细胞库或CD8+ T细胞功能。在停止抗逆转录病毒治疗后，单独接种疫苗可短暂降低病毒设定点。IL-15诱导CD4+效应T细胞大量增殖，消除了疫苗接种降低设定点病毒血症的能力。相反，IL-7既不增强也不降低疫苗的效果，并且与tgf - β表达的减少有关。这些结果强调了在体内测试免疫调节方法以评估hiv -1感染者的潜在风险和益处的重要性。多年来，我们的临床前数据为人体试验的启动和继续提供了原则证明。基于alvac的艾滋病毒候选疫苗目前正在泰国进行成人III期试验，乌干达正在准备进行新生儿I期试验。DNA和NYVAC-HIV的组合将由EuroVac在健康志愿者中进行测试。最后，ALVAC-HIV的I期和II期治疗试验正在几个地点进行，我计划在美国进行NYVAC-HIV的I期治疗试验

Direct evidence indicates that both Abs and CD8+ T cells contribute to restriction of simian immunodeficiency virus (SIV) replication. In the case of CD4+ T cells, however, it has been difficult to ascertain their contribution as they are also the target for viral infection. SIVmac251 infection of macaques is an excellent model whereby to assess these questions. As preventive vaccination with T cell vaccines ameliorates the virological outcome following viral challenge, we explored strategies to augment virus-specific immune responses in already infected macaques treated with antiretroviral therapy (ART). We demonstrated that CTLA-4 blockade decreases TGF-beta, IDO, and viral RNA expression in tissues of SIVmac251-infected macaques. Regulatory T (Treg) cells are a subset of CD25+CD4+ T cells that constitutively express high levels of cytotoxic T lymphocyte antigen-4 (CTLA-4) and suppress T-cell activation and effector functions. Treg cells are increased in tissues of individuals infected with HIV-1 and macaques infected with simian immunodeficiency virus (SIVmac251). In HIV-1 infection, Treg cells could exert contrasting effects: they may limit viral replication by decreasing immune activation, or they may increase viral replication by suppressing virusspecific immune response. Thus, the outcome of blocking Treg function in HIV/SIV should be empirically tested. We demonstrated that CD25+ T cells inhibit virus-specific T-cell responses in cultured T cells from blood and lymph nodes of SIV-infected macaques. We investigated the impact of CTLA-4 blockade using the anti-CTLA-4 human antibody MDX-010 in SIV-infected macaques treated with antiretroviral therapy (ART). CTLA-4 blockade decreased expression of the tryptophan-depleting enzyme IDO and the level of the suppressive cytokine transforming growth factor-beta (TGF-beta) in tissues. CTLA-4 blockade was associated with decreased viral RNA levels in lymph nodes and an increase in the effector function of both SIV-specific CD4+ and CD8+ T cells. Therefore, blunting Treg function in macaques infected with SIV did not have detrimental virologic effects and may provide a valuable approach to complement ART and therapeutic vaccination in the treatment of HIV-1 infection. Acute HIV/SIV infection results in severe CD4+ T cell depletion in lymphoid compartments. During the chronic phase of infection, CD4+ T cell numbers rebound in blood but remain low in the gut-associated lymphoid tissue (GALT), even when viral replication is suppressed by ART. Thus, strategies to repopulate lymphoid compartments may ameliorate the clinical outcome of HIV/SIV infection. Interleukin (IL)-7 is a key cytokine for the maintenance of homeostatic proliferation of T cells. In HIV/SIV infection, IL-7 expression is increased, likely to compensate for T cell loss, suggesting that supraphysiological administration of IL-7 could provide additional benefit. However, the ability of T cells to respond to IL-7 is dependent on the level of expression of the IL-7 receptor (IL-7R) in T cells in various body compartments. We investigated the proportion of IL-7R+ T cells in blood, spleen, gut, and genitourinary tract of healthy and SIV-infected macaques with various degrees of CD4+ T cell depletion. We found that the percentage of T cells expressing IL-7R was significantly lower in both CD4+ and CD8+ T cell subsets in SIV-infected macaques than in healthy animals and this decrease directly correlated with the CD4+ T cell number. Importantly, the proportion of CD4+ and CD8+ T cells expressing IL-7R in blood paralleled that found in tissues. IL-7R+ T cells within the SIV-specific CD8+ T cells varied and were lowest in most tissues of viremic macaques, likely reflecting continuous antigen stimulation of effector cells. We showed that IL-15 abrogates vaccine-induced decrease in virus level in SIVmac251-infected macaques. The loss of CD4+ T cells and the impairment of CD8+ T cell function in HIV infection suggest that pharmacological treatment with IL-7 and IL-15, cytokines that increase the homeostatic proliferation of T cells and improve effector function, may be beneficial. However, these cytokines could also have a detrimental effect in HIV-1-infected individuals, because both cytokines increase HIV replication in vitro. We assessed the impact of IL-7 and IL-15 treatment on viral replication and the immunogenicity of live poxvirus vaccines in SIVmac251-infected macaques (Macaca mulatta). Neither cytokine augmented the frequency of vaccine-expanded CD4+ or CD8+ memory T cells, clonal recruitment to the SIV-specific CD8+ T cell pool, or CD8+ T cell function. Vaccination alone transiently decreased the viral set point following antiretroviral therapy suspension. IL-15 induced massive proliferation of CD4+ effector T cells and abrogated the ability of vaccination to decrease set point viremia. In contrast, IL-7 neither augmented nor decreased the vaccine effect and was associated with a decrease in TGF-beta expression. These results underscore the importance of testing immunomodulatory approaches in vivo to assess potential risks and benefits for HIV-1-infected individuals. Over the years, our preclinical data provided proof of principle for the initiation and continuation of human trials. ALVAC-HIV-based vaccine candidates are now in a phase III trial in adults in Thailand and a phase I trial in neonates in Uganda is being prepared. The combination of DNA plus NYVAC-HIV will be tested by EuroVac in healthy volunteers. Lastly, therapeutic phase I and II trials with ALVAC-HIV are ongoing at several sites and I plan to perform a phase I therapeutic trial with NYVAC-HIV in the U.S