Lysosomal phospholipase A2 in autoimmune disease

溶酶体磷脂酶 A2 在自身免疫性疾病中的作用

基本信息

批准号：
8017485
负责人：
JAMES ALAN SHAYMAN
金额：
$ 32.59万
依托单位：
UNIVERSITY OF MICHIGAN AT ANN ARBOR
依托单位国家：
美国
项目类别：
财政年份：
2010
资助国家：
美国
起止时间：
2010-02-01 至 2014-11-30
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8017485
关键词：
Apoptotic Autoimmune Diseases Autoimmune Process Bacteriophages Binding Cells Ceramides Clinical Research Defect Digestion Disease EGF gene Eating Electrostatics Enzymes Exhibits Family Gene Mutation Genes Glomerulonephritis Hepatosplenomegaly Human Hydralazine Immunoglobulins Immunotherapy Impairment Kidney Failure Knockout Mice Laboratories Lecithin Lupus Membrane Lipids Modeling Molecular Mus Names Pathogenesis Pharmaceutical Preparations Phenocopy Phenotype Phospholipase Phospholipase A2 Phospholipid Degradation Pathway Phospholipids Procainamide Quinidine Reporting Secondary to Signal Transduction Spleen Stimulus Systemic Lupus Erythematosus Testing Zymosan base drug induced lupus enzyme activity human MERTK protein insight lymph nodes macrophage milk fat globule novel public health relevance receptor research study response uptake wasting

项目摘要

DESCRIPTION (provided by applicant): Systemic lupus erythematosus historically has been and still remains a poorly understood autoimmune disorder. Recent advances have been made in identifying lupus promoting single gene alterations that phenocopy many aspects of lupus in humans. Despite these advances there remains no unifying hypothesis and no new mechanism based, directed immunotherapy for this disease. In recent years several clinical and experimental studies have pointed to the impairment in the clearance of apoptotic cells as a common feature of lupus. As the molecular basis for the recognition, binding, and uptake of apoptotic cells by macrophages has become better defined, gene alterations associated with the impaired expression of phagocytic receptors for "eat me" signals are associated with murine models of lupus. Examples include the milk fat globule-EGF factor 8 and the c-mer proto-oncogene tyrosine kinase. The phospholipid lyso- phosphatidylcholine has been identified as an important "find me" signal for the recruitment of macrophages involved in the clearance of apoptotic cells. However, how lyso-phosphatidylcholine is generated as a find me signal is unknown and the identification of comparable alterations in the genes encoding the enzyme or enzymes involved in lyso-PC formation that would result in a lupus phenotype have not been reported. Our laboratory discovered, cloned, and characterized a novel phospholipase A2 named lysosomal phospholipase A2. This enzyme is distinct among the family of phospholipase A2s. Lysosomal phospholipase A2 is characterized by an acidic pH optimum, the ability to transacylate ceramide, and it secretion from macrophages in response to phagocytic stimuli such as zymosan. A knockout mouse, lacking the expression of lysosomal phospholipase A2 is characterized by a late onset autoimmune phenotype that mimics most aspects of lupus. These mice develop lymphoproliferation with hepatosplenomegaly, wasting, and renal failure. The mice exhibit markedly positive ANAs, anti-dsDNA titers, high circulating immunoglobulin levels, and glomerulonephritis. The spleens and lymph nodes are characterized by the persistence of high levels of apoptotic bodies in association with resident macrophages, consistent with a defect in the clearance of apoptotic cells. Based on these observations, the following primary hypothesis is proposed. Lysosomal phospholipase A2 is necessary for the digestion and clearance of apoptotic cells by macrophages. The following specific aims are proposed to test this hypothesis: 1) To immunologically phenotype LPLA2 null mice. 2) To determine the mechanism by which the absence of lysosomal phospholipase A2 inhibits or eliminates the clearance of apoptotic cells by macrophages. 3) To determine lysosomal phospholipase A2 is either sufficient or necessary to rescue the lupus phenotype in the LPLA2 null mice. 4) To determine whether inhibition of lysosomal phospholipase A2 by hydralazine, quinidine, and procainamide is the basis for drug induced lupus. PUBLIC HEALTH RELEVANCE: We have discovered and characterized a new lysosomal phospholipase A2. Knockout mice, deficient in the activity of this enzyme, develop a late onset autoimmune phenotype with features similar to systemic lupus erythematosus. Understanding the mechanisms whereby impaired degradation of phospholipids result in the autoimmune phenotype may provide new insights into the pathogenesis of lupus and potential new targets for therapy.

描述（由申请人提供）：从历史上看，全身性红斑狼疮一直是并且仍然是一种自身免疫性障碍。在识别狼疮促进单个基因改变的过程中，已经取得了最新进展，该基因改变了人类狼疮的许多方面。尽管有这些进展，但仍未统一假设，也没有针对该疾病的新机制的定向免疫疗法。近年来，一些临床和实验研究表明，凋亡细胞清除是狼疮的常见特征。作为巨噬细胞对凋亡细胞的识别，结合和摄取的分子基础，已经更好地定义了与吞噬受体的表达相关的基因改变，“饮食我”信号与狼疮的鼠模型有关。例子包括牛奶脂肪球-EGF因子8和C-MER原始癌基因酪氨酸激酶。磷脂溶菌磷脂酰胆碱已被确定为重要的“找到我”信号，用于募集参与凋亡细胞清除的巨噬细胞。然而，如何生成溶酶 - 磷脂酰胆碱作为发现我的信号，尚不清楚，并且尚未报道与溶血-PC形成的酶或酶相当变化的鉴定，这将导致狼疮表型。我们的实验室发现，克隆并表征了一种新型的磷脂酶A2，称为溶酶体磷脂酶A2。这种酶在磷脂酶A2家族中是不同的。溶酶体磷脂酶A2的特征在于酸性pH最佳，转囊酸酯的能力和巨噬细胞的IT分泌，以响应吞噬细胞刺激（例如Zymosan）。缺乏溶酶体磷脂酶A2表达的敲除小鼠的特征是迟到的自身免疫性表型，该表型模仿了狼疮的大多数方面。这些小鼠随着肝肾上腺全球，浪费和肾功能衰竭而形成淋巴细胞增生。小鼠表现出明显的阳性ANA，抗DSDNA滴度，高循环的免疫球蛋白水平和肾小球肾炎。脾脏和淋巴结的特征是高水平的凋亡人体与居民巨噬细胞相关的持久性，与凋亡细胞清除的缺陷一致。基于这些观察结果，提出了以下主要假设。溶酶体磷脂酶A2对于巨噬细胞对凋亡细胞的消化和清除是必需的。提出了以下特定目的来检验以下假设：1）对免疫学表型LPLA2 NULL小鼠。 2）确定缺乏溶酶体磷脂酶A2抑制或消除巨噬细胞清除凋亡细胞的机制。 3）确定溶酶体磷脂酶是足够或必要的，可以挽救LPLA2 NULL小鼠中的狼疮表型。 4）确定氢酶，奎尼丁和丙酰胺对溶酶体磷脂酶A2的抑制是药物诱导的狼疮的基础。公共卫生相关性：我们发现并描述了一种新的溶酶体磷脂酶A2。敲除小鼠缺乏这种酶的活性，会产生一种迟到的自身免疫性表型，其特征类似于全身性红斑狼疮。了解磷脂降解的机制导致自身免疫性表型可能会为狼疮的发病机理和潜在的治疗靶标提供新的见解。