Dendritic Cell Activation by Mitochondrial Transcription Factor A

描述（由申请人提供）：先天免疫系统旨在防范潜在的危险感染，但最近的研究也表明，我们的免疫系统可以被“自身抗原”激活，这些抗原在严重的急性疾病中被释放，如创伤、胰腺炎或烧伤。在这些情况下，在没有任何可识别的感染（即无菌炎症）的情况下，组织损伤导致免疫系统的广泛激活，这与患者病情的急剧恶化有关。树突状细胞（dc）是首先对受损细胞释放的抗原做出反应的免疫细胞之一，我们实验室的新数据表明，细胞的线粒体成分最能激活dc。特别是，未甲基化（CpG）线粒体DNA与其通常的结合伙伴线粒体转录因子A （TFAM）结合时，被证明可以有效地激活DCs。我们假设线粒体抗原TFAM和CpG DNA在急性细胞损伤的情况下诱导DC激活中起主要作用。为了验证这一假设，我们提出了三个主要的研究目标：1)我们将确定RAGE和TLR-9/MyD88通路是否独立地促进了TFAM和CpG DNA对DC的激活，2)我们将确定PI-3K/Akt信号在促进DC型1干扰素对TFAM和CpG DNA的反应中的作用，3)我们将确定TFAM蛋白的DNA结合pro- lys - arg序列是否负责其促炎生物学活性。在这些研究中，我们将使用人类dc和从缺乏RAGE、TLR-9和MyD88的转基因小鼠中获得的dc。我们还将确定TFAM和CpG DNA是否负责小鼠免疫反应的激活。这些实验将研究一种针对TFAM的抗体，这种抗体可能作为一种机制，在急性细胞死亡时阻断免疫系统的激活，这将对治疗危重动物和人类有重要的应用。公共卫生相关性：该项目将确定将细胞和组织损伤与免疫系统激活联系起来的机制，这是急性疾病患者（如创伤、胰腺炎或烧伤患者）常见且可能危及生命的并发症。我们实验室最近的研究表明，树突状细胞是我们免疫系统的第一道防线，在受到受损细胞释放的线粒体成分的反应中，树突状细胞被强烈激活。该项目将重点研究一种特殊的线粒体蛋白，线粒体转录因子a (TFAM)，参与免疫系统促进炎症的机制。该项目对理解细胞和组织损伤（如许多急性疾病中常见的损伤）如何诱导免疫系统激活具有重要意义，这对宿主可能有害。

DESCRIPTION (provided by applicant): The innate immune system is designed to guard against potentially dangerous infections, but recent studies also show that our immune system can become activated by "self-antigens" which are released during severe acute illnesses, such as trauma, pancreatitis or burns. Under these conditions, tissue damage results in widespread activation of the immune system in the absence of any identifiable infection (i.e., sterile inflammation), which is associated with a dramatic worsening of the patient's condition. Dendritic cells (DCs) are among the immune cells that first respond to antigens released from damaged cells, and new data from our laboratory indicates that mitochondrial components of the cell most vigorously activate DCs. In particular, unmethylated (CpG) mitochondrial DNA when combined with its usual binding partner, mitochondrial transcription factor A (TFAM), is shown to potently activate DCs. We hypothesize that the mitochondrial antigens TFAM and CpG DNA play a major role in the induction of DC activation in the context of acute cell damage. To test this hypothesis three major research aims are proposed: 1) We will determine if RAGE and TLR-9/MyD88 pathways independently contribute to DC activation by TFAM and CpG DNA, 2) we will determine the role of PI-3K/Akt signaling in promoting DC Type 1 interferon responses to TFAM and CpG DNA, 3) we will determine if the DNA-binding Pro-Lys-Arg sequence of TFAM protein is responsible for its pro- inflammatory biological activity. For these studies we will use human DCs and DCs obtained from genetically altered mice lacking RAGE, TLR-9, and MyD88. We will also determine if TFAM and CpG DNA are responsible for the activation of the immune response in mice. These experiments will investigate an antibody directed against TFAM, which may serve as a mechanism to block the activation of the immune system in response to acute cell death, which would have important applications for the treatment of critically ill animals and humans. PUBLIC HEALTH RELEVANCE: This project will determine the mechanisms linking cell and tissue damage to activation of the immune system, which is a common and potentially life-threatening complication in acutely ill patients, such as those suffering from trauma, pancreatitis or burn injuries. Recent studies in our laboratory indicate that dendritic cells, which represent a first line of defense of our immune system, are strongly activated in response to components of mitochondria, which are released from damaged cells. This project will focus on the mechanisms by which a particular mitochondrial protein, mitochondrial transcription factor A (TFAM), engages the immune system to promote inflammation. This project has important implications for understanding how cell and tissue damage, such as commonly occurs in many acute illnesses, can induce activation of the immune system, which is potentially harmful to the host.