Tyrosine Kinase inhibition: The New Front in HIV Cure Efforts

项目摘要 根除HIV-1的主要障碍是存在一个小型但长期存在的潜伏水库，即 不受抗逆转录病毒治疗的影响。这一储存库主要通过记忆T细胞的天然能力持续存在 在γ、c-细胞因子IL-7和IL-15的作用下进行稳态增殖。此外，HIV-1还感染人的细胞 髓系髓系，如巨噬细胞，一种能穿透受保护组织的细胞类型，包括中央 神经系统，并引发一系列神经损害，这些损害可以持续在 抗逆转录病毒治疗。最近，几项研究表明，达沙替尼是一种酪氨酸激酶抑制剂，可以 FDA批准用于治疗慢性髓细胞白血病，有三种新的活性，可以特异性地 影响HIV-1感染和潜伏宿主的持久性。 达沙替尼的第一个新活性是阻止体内平衡增殖的能力。因此，在目标1中，我们测试 假设达沙替尼将阻止潜伏感染的T细胞的稳态增殖，从而阻止 潜在储油层的维护，导致随着时间的推移衰变更快。我们还建议鉴定酪氨酸 激酶(S)，其被达沙替尼抑制阻止稳态增殖，并假设该靶点(S)是 不同于达沙替尼的同源靶点(Src、c-Abl和c-Kit)。 达沙替尼的第二个活性是它通过一种不寻常的机制阻止艾滋病毒-1感染的能力，这种机制 包括去磷酸化和激活SAMHD1，一个有效的病毒限制因子，在T细胞和 巨噬细胞。导致SAMHD1苏氨酸-592下游去磷酸化的信号通路 达沙替尼的作用机制尚不清楚，但明显不同于干扰素信号的下游。因为有这么高 抑制效应在T细胞和髓系细胞中的效力，达沙替尼抑制的途径代表 令人信服的发现目标(目标2的重点)和新疗法的开发。 达沙替尼与病毒感染相关的第三个活性在于其强大的免疫调节活性。 达沙替尼广泛应用于慢性粒细胞白血病患者并进行研究，可导致大颗粒扩张 具有细胞毒性或NK表型的淋巴细胞(LGL)，细胞毒性群体颗粒酶B+也增加 作为一种强大的免疫反应，类似于对CMV的自然反应。所有这些影响似乎都有助于 达沙替尼的高效抗白血病作用。因此，这些研究的第三个目标将是测试 假设达沙替尼将增强针对艾滋病毒感染细胞的先天细胞免疫机制。 总之，我们建议研究达沙替尼的这些新的和有前途的抗病毒活性。 艾滋病毒-1感染的背景，重点是了解生物机制和评估潜在的 为将来的临床应用做准备。因此，达沙替尼代表了我们根除HIV-1斗争的新战线。

PROJECT ABSTRACT The major obstacle for HIV-1 eradication is the existence of a small but long-lived latent reservoir that is impervious to antiretroviral therapy. This reservoir persists largely through the natural ability of memory T cells to homeostatically proliferate in response to γc-cytokines IL-7 and IL-15. In addition, HIV-1 also infects cells of the myeloid lineage, such as macrophages, a cell type that can penetrate protected tissues including the central nervous system, and precipitate a spectrum of neurological impairments that can persist in the setting of antiretroviral therapy. Recently, several studies have demonstrated that dasatinib, a tyrosine kinase inhibitor that is FDA-approved for the treatment of chronic myeloid leukemia, has three novel activities that can specifically impact HIV-1 infection and the persistence of latent reservoirs. The first novel activity of dasatinib is the ability to block homeostatic proliferation. Thus, in Aim 1 we test the hypothesis that dasatinib will block the homeostatic proliferation of latently infected T cells and thus prevent maintenance of the latent reservoir, resulting in a faster decay over time. We also propose to identify the tyrosine kinase(s) whose inhibition by dasatinib blocks homeostatic proliferation and hypothesize that such target(s) is different from the cognate targets of dasatinib (Src, c-Abl and c-Kit). A second activity of dasatinib is its ability to block infection by HIV-1 by an unusual mechanism that involves dephosphorylation and activation of SAMHD1, a potent viral restriction factor, both in T-cells and macrophages. The signaling pathway leading to dephosphorylation of SAMHD1 at threonine-592 downstream of dasatinib is unknown, but is clearly different from that downstream of IFN signalling. Because of the high potency of the inhibitory effect in both T-cells and myeloid cells, the dasatinib-inhibited pathway represents a compelling target for discovery (the focus of Aim 2) and development of novel therapeutics. A third activity of dasatinib with relevance to viral infection lies in its potent immunomodulatory activities. Dasatinib, extensively administered and studied to CML patients, induces an expansion of large granular lymphocytes (LGLs) with cytotoxic or NK phenotype, an increase in cytotoxic populations granzyme B+, as well as a potent immune response resembling natural responses against CMV. All these effects appear to contribute to the highly effective anti-leukemic effects of dasatinib. Thus, the third Aim of these studies will be to test the hypothesis that dasatininb will enhance innate cellular immune mechanisms against HIV-infected cells. In summary, we propose to investigate these novel and promising antiviral activities of dasatinib in the context of HIV-1 infection, with a focus on understanding the biological mechanisms and evaluating the potential for future clinical application. Dasatinib therefore represents a novel front in our fight to eradicate HIV-1.