The role of SPNS2 in T cell responses

项目摘要 信号转导脂鞘氨醇1-磷酸(S1P)在免疫应答中起着多种作用。多数 值得注意的是，S1P调节淋巴细胞从最初被激活的淋巴器官退出进入循环， 在那里它们可以到达感染的地方。淋巴组织中S1P浓度高于淋巴组织 (Ln)。这种梯度引导淋巴细胞从LN进入淋巴，最终回到血液中。类似地， 血液中的高S1P会吸引淋巴细胞离开脾进入循环。T细胞感知S1P梯度 主要通过G蛋白偶联受体S1P受体1(S1PR1)。FTY720，一种针对四个人的药物 包括S1PR1在内的S1P受体成为FDA批准的第一个治疗多发性硬化症的口服药物。通过 FTY720阻止淋巴细胞从淋巴器官出口，阻止淋巴细胞进入中央 神经系统。针对S1PR1的第二代药物也在第二阶段试验中显示出希望 牛皮癣和结肠炎。不幸的是，这些药物的使用受到限制，因为它们也针对S1PR1 血管内皮细胞和心肌细胞，导致严重的副作用。我们最近发现少校 促进剂超家族转运体SPNS2向淋巴但不是血液供应S1P，使其成为一种有前途的新的 能够对S1P信号进行空间特异性调制的药物靶点。血S1P水平保持在约 80%的SPNS2缺陷小鼠，这些小鼠表现出正常的肺血管通透性，不同于 FTY720处理的小鼠。相比之下，SPNS2缺陷小鼠淋巴中的S1P水平显著降低。在……里面 SPNS2缺陷小鼠，T细胞正常从脾进入血液，但不能从层粘连蛋白进入淋巴，导致 T细胞从脾到LN的重新分布和循环细胞的损失。我们建议以SPNS2为目标 可以将T细胞捕获在LN中，而不会产生实质性的心血管副作用。然而，这些研究是进行的。 在动态平衡中，SPNS2在炎症或疾病中的作用尚不清楚。在这里，我们将 研究SPNS2如何在免疫反应的效应器和记忆阶段影响T细胞功能。 首先，我们将讨论SPNS2是否会产生淋巴S1P，从而引导T细胞在 免疫反应，或者是否在炎症中其他转运蛋白上调并可以补偿 SPNS2的S失利。这是确定SPNS2是否为有效的药物靶点的关键问题。 其次，我们将检验SPNS2在炎症过程中向LN实质提供S1P的假设 反应，钝化引导出口的梯度，减缓(但不是停止)T细胞通过发炎的 在。第三，我们将确定SPNS2是否调节记忆T细胞的分化和存活、延伸 我们令人惊讶的发现SPNS2/S1PR1信号调节幼稚T的线粒体含量和生存 细胞。提出的AIMS将检验SPNS2的S作为免疫抑制治疗靶点的潜力，并推动 我们对S1P在免疫反应中作用的基本理解。

Project Summary The signaling lipid sphingosine 1-phosphate (S1P) plays many roles in the immune response. Most notably, S1P regulates lymphocyte exit from lymphoid organs, where they are initially activated, into circulation, where they can travel to the site of infection. The concentration of S1P is higher in lymph than lymph nodes (LN). This gradient guides lymphocytes out of the LN into lymph and ultimately back to blood. Similarly, the high S1P within blood attracts lymphocytes to exit the spleen into circulation. T cells sense the S1P gradient primarily through the G protein-coupled receptor S1P receptor 1 (S1PR1). FTY720, a drug that targets four S1P receptors including S1PR1, became the first FDA-approved oral therapeutic for multiple sclerosis. By blocking lymphocyte exit from lymphoid organs, FTY720 prevents lymphocytes from accessing the central nervous system. Second-generation drugs that target S1PR1 have also shown promise in Phase II trials for psoriasis and colitis. Unfortunately, use of these drugs is limited because they also target S1PR1 in endothelial cells and cardiomyocytes, resulting in serious side effects. We recently found that the major facilitator superfamily transporter SPNS2 supplies S1P into lymph but not blood, making it a promising new drug target that would enable spatially specific modulation of S1P signaling. Blood S1P levels remain at about 80% of baseline in SPNS2-deficient mice, and these mice exhibit normal lung vascular permeability, unlike FTY720-treated mice. By contrast, S1P levels in lymph are dramatically reduced in SPNS2-deficient mice. In SPNS2-deficient mice, T cells exit the spleen into blood normally but cannot exit LN into lymph, leading to a redistribution of T cells from spleen to LN and a loss of circulating cells. We proposed that targeting SPNS2 could trap T cells in LN without substantial cardiovascular side effects. However, these studies were carried out in homeostasis, and the role of SPNS2 during inflammation or disease is poorly understood. Here, we will investigate how SPNS2 affects T cell function during the effector and memory stages of an immune response. First, we will address whether SPNS2 generates the lymph S1P that guides T cell exit from LN during an immune response, or whether in inflammation other transporters are upregulated and can compensate for SPNS2's loss. This is the key question to determine whether SPNS2 would be an effective drug target. Second, we will test the hypothesis that SPNS2 supplies S1P into the LN parenchyma during an inflammatory response, blunting the gradient that guides exit and slowing (but not halting) T cell transit through an inflamed LN. Third, we will determine whether SPNS2 regulates memory T cell differentiation and survival, extending our surprising finding that SPNS2/S1PR1 signaling regulates mitochondrial content and survival in naïve T cells. The proposed aims will test SPNS2's potential as a target for immunosuppressive therapy, and advance our basic understanding of the role of S1P in the immune response.