CRAC Channel Deficiency in Immunity to Infection

在这项拨款申请中提出的研究的长期目标是了解免疫系统细胞中钙离子内流对感染的免疫作用以及作为免疫缺陷的一个原因。我们的中心假设是，通过所谓的CRAC通道的钙内流是许多类型的免疫细胞发挥功能所必需的，因此对感染的免疫力是必需的。我们将研究CRAC通道功能遗传性缺陷的患者，并使用CRAC通道基因基因缺失的小鼠作为感染的动物模型。 我们之前的研究表明，CRAC通道功能遗传缺陷的患者在生命早期会反复发生危及生命的感染。CREC通道是由ORAI和STIM家族基因编码的，我们发现了第一批ORAI1和STIM1基因突变的患者。这些基因突变会破坏钙离子的内流，损害免疫细胞功能，导致一种独特的免疫缺陷综合征，其特征是严重感染、自身免疫、肌肉张力低下以及牙齿形成和汗腺功能缺陷。 CRAC缺陷患者的免疫缺陷在很大程度上归因于T细胞功能受损，T细胞的激活依赖于CRAC通道。我们发现，在多发性硬化症和炎症性肠病动物模型中，小鼠STIM1和ORAI1基因的破坏可以防止T细胞驱动的自身免疫性疾病，从而强调了CRAC通道在T细胞中的重要作用。CRAC通道基因也在其他免疫细胞的功能中发挥作用，但它们在体内对感染的免疫反应中的重要性尚不清楚。我的实验室在研究CRAC通道有助于宿主防御病原体的机制方面处于独特的地位，因为我们正在研究CRAC通道基因遗传突变的患者。此外，我们还培育了在特定的免疫细胞群体中缺乏STIM和ORAI基因表达的基因工程小鼠。这些小鼠是研究CRAC渠道对感染免疫作用的理想工具。 这项提案的具体目标描述了我们将重点关注的以下研究领域。(1)我们将分析疑似CRAC通道功能缺陷的免疫缺陷患者的遗传缺陷。这些研究的目标之一是量化正常免疫功能和防止感染所需的最低钙内流。(2)我们将确定T细胞和NK细胞上的CRAC通道如何控制对病毒和细菌感染的免疫，而CRAC通道功能受损的患者对病毒和细菌感染易感。(3)我们将调查是否需要CRAC通道来控制(分枝杆菌)和真菌病原体的感染，并确定CRAC通道如何调节先天性免疫系统中细胞的功能。综上所述，我们的研究将确定CRAC渠道如何控制对感染的免疫。了解钙内流对免疫反应的作用对于评估CRAC通道抑制作为未来治疗自身免疫性和变态反应性疾病的治疗潜力至关重要。

The long-term goal of the research proposed in this grant application is to understand the role of calcium influx in cells of the immune system for immunity to infection and as a cause of immunodeficiency. Our central hypothesis is that calcium influx through so-called CRAC channels is required for the function of many types of immune cells and thus immunity to infection. We will study patients with inherited defects in CRAC channel function and use mice with genetic deletion of CRAC channel genes in animal models of infection. We previously showed that patients with inherited defects in CRAC channel function suffer from recurrent, life-threatening infections early in life. CRAC channels are encoded by ORAI and STIM family genes and we identified the first patients with mutations in ORAI1 and STIM1 genes. These mutations, which abolish calcium influx and impair immune cell function, cause a unique immunodeficiency syndrome that is characterized by severe infections, autoimmunity, muscular hypotonia and defects in tooth formation and sweat gland function. Immunodeficiency in CRAC deficient patients has been attributed largely to the impaired function of T cells, white blood cells whose activation is dependent on CRAC channels. The important role of CRAC channels in T cells is emphasized by our finding that disruption of STIM1 and ORAI1 genes in mice prevents T-cell driven autoimmune disease in animal models of multiple sclerosis and inflammatory bowel disease. CRAC channel genes are emerging to play a role for the function of other immune cells as well but their importance for immune responses to infection in vivo is not well understood. My lab is in a unique position to study the mechanisms by which CRAC channels contribute to host defense against pathogens because we are studying patients with inherited mutations in CRAC channel genes. In addition, we generated genetically engineered mice that lack expression of STIM and ORAI genes in defined populations of immune cells. These mice are ideal tools to study the role of CRAC channels for immunity to infection. The specific aims of this proposal describe the following areas of research that we will focus on. (1) We will analyze the genetic defects in immunodeficient patients with suspected defects in CRAC channel function. One goal of these studies is to quantify the minimal Ca2+ influx that is required for normal immune function and protection from infection. (2) We will determine how CRAC channels in T cells and NK cells control immunity against viral and bacterial infections to which patients with impaired CRAC channel function are susceptible. (3) We will investigate if CRAC channels are required to control infection with (mycobacterium) tuberculosis and fungal pathogens and determine how CRAC channels regulate the function of cells in the innate immune system. Taken together, our studies will determine how CRAC channels control immunity to infection. Understanding the role of calcium influx for immune responses is essential to assess the therapeutic potential of CRAC channel inhibition as a treatment for autoimmune and allergic diseases in the future.