Dipyridamole as a Modulator of HIV-1 Inflammation by Adenosine Regulation

描述(申请人提供)：尽管抗逆转录病毒疗法受到病毒学抑制，但细胞免疫激活和全身炎症水平很少恢复到HIV-1血清阴性患者的水平。我们认为，HIV-1+个体胞外腺苷(ADO)产生的缺陷在ADO-A2AR-cAMP信号通路无法抑制HIV-1相关慢性炎症中起重要作用。胞外ADO是在应激条件下，通过胞外酶CD39和CD73对ATP的水解而产生的。虽然这些酶在小鼠的调节性T细胞中共表达，但在人类中，我们已经证实了以前的研究表明，它们属于不同的CD4+T细胞亚群。此外，我们已经观察到HIV-1感染中的CD4+CD73+T细胞的频率和绝对数的减少，而不考虑对ART的病毒学抑制。CD4+CD73+T细胞与T细胞免疫激活及血浆C反应蛋白(CRP)水平呈负相关。我们推测，由于CD4+CD73+T细胞的丢失，ADO的产生减少，导致ADO信号通路无法控制HIV-1感染的慢性炎症。我们建议进行一项I/II期、随机、双盲、安慰剂对照、部分交叉的初步研究，评估双嘧达莫(DP)对细胞免疫激活和炎症的影响。双嘧达莫是FDA批准的一种药物，可增加细胞外ADO水平。我们将随机选择40名HIV-1+受试者，这些受试者接受抗逆转录病毒治疗，并接受CD4+T细胞计数为D500细胞/mm3，服用12周的DP或安慰剂。主要终点是CD8+T细胞共表达CD38和HLA-DR的比例和血浆IL-6水平的变化。次级终点将评估12周和24周DP治疗对免疫学和病毒学参数的影响，包括：CD4+T细胞激活和细胞周期、T细胞成熟亚群的频率、单核和巨噬细胞激活、肠道粘膜T细胞激活、炎症和凝血生物标记物的血浆水平以及残留病毒表达。在目标2中，我们将确定各种免疫学参数的变化是否会转化为可测量的临床结果。因此，在我们的临床试验中，我们将评估DP疗法是否可以通过对HIV-1阳性受试者实施肱动脉血流介导的扩张来改善血管功能。在目标3中，由于我们在体外已经证明ADO可以抑制T细胞的激活和促炎细胞因子的分泌，我们将在体内研究CD73的表达和ADO-A2AR-cAMP信号通路是否真的可以调节HIV-1相关的炎症。我们将测定外周血和肠道粘膜组织中表达CD73的免疫细胞的频率以及参与信号通路的嘌呤水平，并探讨它们与免疫激活和炎症的关系。通过阐明HIV-1相关免疫失调的具体机制，我们的研究结果可能会导致新的干预措施，旨在预防或限制HIV-1感染中慢性炎症和免疫激活的影响。

DESCRIPTION (provided by applicant): Despite virologic suppression on ART, the levels of cellular immune activation and systemic inflammation rarely return to levels seen in HIV-1-seronegative individuals. We believe that a defect in extracellular adenosine (ADO) production in HIV-1+ individuals plays an important role in the inability of the ADO-A2AR- cAMP signaling pathway to suppress chronic HIV-1-associated inflammation. Extracellular ADO is generated in conditions of stress through hydrolysis of ATP by the ectoenzymes, CD39 and CD73. While these enzymes are co-expressed in murine regulatory T cells, in humans we have confirmed previous studies that they belong in separate CD4+ T cell subsets. Furthermore, we have observed decreases in the frequency and absolute numbers of CD4+CD73+ T cells in HIV-1 infection, regardless of virologic suppression on ART. CD4+CD73+ T cells inversely correlate with T cell immune activation as well as plasma levels of C-reactive protein (CRP). We hypothesize that decreased ADO production, due to the loss of CD4+CD73+ T cells, contributes to the inability of the ADO-signaling pathway to control the chronic inflammation in HIV-1 infection. We propose to conduct a phase I/II, randomized, double blind, placebo controlled, partial crossover pilot study evaluating the effect of Dipyridamole (DP), an FDA-approved drug proven to increase extracellular ADO levels, on cellular immune activation and inflammation. We will randomize 40 HIV-1+ subjects virally suppressed on ART and with CD4+ T cell counts d500 cells/mm3, to 12 weeks of either DP or placebo. The primary endpoints are the changes in the proportion of CD8+ T cell co-expressing CD38 and HLA-DR and the plasma levels of IL-6. Secondary endpoints will assess the impact of 12 and 24 weeks DP therapy on immunologic and virologic parameters including: CD4+ T cell activation and cell cycling, frequencies of T cell maturation subsets, monocyte and macrophage activation, gut mucosal T cell activation, plasma levels of biomarkers of inflammation and coagulation, and residual viral expression. In Aim 2, we will determine whether changes in the various immunologic parameters will translate to a measurable clinical outcome. As such we will evaluate whether DP therapy can improve vascular function by performing brachial artery flow-mediated dilation on the HIV-1+ subjects in our clinical trial. In Aim 3, since we have shown in vitro that ADO can suppress T cell activation and secretion of pro-inflammatory cytokines, we will investigate in vivo whether CD73 expression and the ADO-A2AR-cAMP signaling pathway can indeed regulate HIV-1-associated inflammation. We will determine frequencies of immune cells expressing CD73 in peripheral blood and gut mucosal tissue as well as the levels of the purines involved in the signaling pathway and investigate their associations with immune activation and inflammation. By elucidating specific mechanisms responsible for HIV-1-associated immune dysregulation, results of our study may lead to new interventions aimed at preventing or limiting the impact of chronic inflammation and immune activation in HIV-1 infection.