Harnessing NK Memory To Protect Against HIV Infection

 描述（由申请方提供）：本提案的目的是利用新型HIV包膜（HIVenv）-负载花粉粒（PG）制剂的口服疫苗接种，以引发快速免疫应答，包括自然杀伤（NK）细胞中的HIVenv特异性免疫记忆，直接杀死胃肠道（GI）粘膜中的HIV感染细胞，以预防HIV感染。NK细胞是免疫系统的重要抗病毒武器;它们对感染迅速作出反应，在没有预先激活的情况下杀死受感染的细胞，同时接合多个靶标，并分泌大量的抗病毒细胞因子，如干扰素γ。此外，NK细胞还通过抗体依赖性细胞介导的细胞毒性（ADCC）与B细胞介导的Ab应答相互作用，ADCC是一种快速的NK细胞介导的裂解功能，其仅需要通过结合甚至可能不是中和性的Ab来标记靶细胞。如果这些独特的NK细胞介导的效应子功能可以通过疫苗接种得到增强，并在HIV进入部位迅速诱导，则有可能预防系统性HIV感染的建立。为了支持这一假设，Paust博士（PI）及其同事最近证明，与传统范式相反，NK细胞亚群介导了对HIV包膜的Ag特异性免疫记忆。然而，通过疫苗接种可靠地激发强粘膜免疫仍然是一个挑战。最近，吉尔博士（Co-I）开创了一种独特的方法，使用花粉粒（PG）进行口服疫苗接种。PG，由于其天然韧性，在胃的恶劣环境中存活，并安全地将抗原（Ag）运送到肠，在那里它们穿过肠上皮被吸附。使用这些方法，我们生成了数据，其显示用卵清蛋白（OVA）负载的石松孢子（LS-OVA）口服接种导致（i）血清和粪便中的OVA特异性Ab，（ii）OVA特异性记忆NK细胞，其在体外再刺激后去活化、杀死和介导ADCC，以及（iii）口服激发后记忆NK细胞向粘膜募集。我们进一步发现，HIVenv在体外和体内激发人NK细胞的回忆反应。基于这些考虑，我们假设具有抗HIV活性的人NK细胞代表能够预防系统性HIV感染的潜在效应细胞群体，并且口服LS-env疫苗接种激发HIV特异性记忆NK细胞应答。我们建议确定一种新的口服LS-env疫苗在人源化小鼠中诱导长寿命HIV特异性粘膜NK细胞记忆应答的功效，并评估NK细胞记忆预防HIV感染的功效。在人类NK细胞中展示具有抗HIV活性的记忆NK细胞，以及通过疫苗接种诱导这些应答的能力将是非常重要的，因为它将鉴定可以被疫苗靶向并针对HIV的新型适应性淋巴细胞亚群。

 DESCRIPTION (provided by applicant): The goal of this proposal is to exploit oral vaccination with a novel HIV envelope (HIVenv)-loaded pollen grain (PG) formulation to elicit a rapid immune response comprising of HIVenv-specific immunological memory in Natural Killer (NK) cells that directly kill HIV infected cells in the gastrointestinal (GI) mucosa, to prevent HIV infection. NK cells are an essential anti-viral weapon of the immune system; they respond quickly to infection, kill infected cells without prior activation, engage multiple targets simultaneously, and secrete large amounts of anti-viral cytokines, such as interferon gamma. Further, NK cells also crosstalk with B cell-mediated Ab- responses through antibody-dependent cell-mediated cytotoxicity (ADCC), a rapid NK cell-mediated lytic function that only requires tagging of target cells by binding Abs that may not even be neutralizing. If these unique NK cell-mediated effector functions could be enhanced through vaccination, and induced rapidly at the site of HIV entry, it may be possible to prevent the establishment of a systemic HIV infection. In support of this postulate, Dr. Paust (PI) and colleagues have recently demonstrated that contrary to conventional paradigm, subsets of NK cells mediate Ag-specific immunological memory to HIV-envelope. However, reliable elicitation of strong mucosal immunity through vaccination remains a challenge. Recently Dr. Gill (Co-I) has pioneered a unique approach that uses pollen grains (PGs) for oral vaccination. PGs, due to their natural toughness, survive the harsh environment of the stomach, and safely ferry antigens (Ags) to the intestine, where they are persorbed cross the intestinal epithelium. Using these methods, we generated data, which show that oral vaccination with ovalbumin (OVA)-loaded lycopodium spores (LS-OVA) results in (i) OVA-specific Abs in serum and fecal matter, (ii) OVA-specific memory NK cells, which degranulate, kill, and mediate ADCC upon in vitro restimulation, and (iii) memory NK cell recruitment to the mucosa upon oral challenge. We further found that HIVenv elicits recall responses in human NK cells in vitro, and in vivo. Based on these considerations, we hypothesize that human NK cells with antiviral activity against HIV represent a potential effector cell population able to prevent systemic HIV infection, and that oral LS-env vaccination elicits HIV-specific memory NK cell responses. We propose to determine the efficacy of a novel oral LS-env vaccine for the induction of long-lived HIV-specific mucosal NK cell-memory responses in humanized mice, and to assess the efficacy of NK cell memory for the prevention of HIV infection. The demonstration of memory NK cells with activity against HIV in human NK cells, and the ability to induce these responses by vaccination would be highly significant, as it would identify a novel adaptive lymphocyte subset that can be targeted by vaccines and directed against HIV.