Group V Phospholipase A2 and Pulmonary Inflammation

描述(申请人提供)：本申请的主要目的是了解一种称为分泌型V组磷脂酶A2(SPLA2)的酶的生物学功能(S)，特别是它与控制感染和肺部炎症有关。V组sPLA2在肥大细胞和巨噬细胞中显著表达，这两种细胞对于感知有害生物进入人体的部位以及产生急性炎症反应至关重要，而急性炎症反应对于有效清除和杀死这些肺部病原体是必不可少的。我们早期的研究表明，该酶调节肺巨噬细胞对白色念珠菌的吞噬和杀灭，并调节肥大细胞对TLR2刺激的信号分子丝裂原活化蛋白激酶的激活。为了实现这些目标，我们将比较缺乏V组sPLA2的巨噬细胞和正常巨噬细胞在酵母多糖刺激后的脂质生成和早期信号事件。我们将在巨噬细胞中表达V组sPLA2的正常和突变形式，以研究酶的结构和功能之间的关系。我们将比较缺乏V组sPLA2的肥大细胞和正常肥大细胞在TLR2刺激下的脂质生成和早期信号事件。我们将研究V组sPLA2在TLR2刺激的肥大细胞中的亚细胞定位。最后，我们将使用缺乏V组sPLA2的小鼠来研究这些发现在真菌肺部感染模型中的相关性。肺部是感染性生物进入体内的主要部位。对这些生物进行有效和适当的炎症反应的能力是生存所必需的。拟议的研究将确定V组磷脂酶A2在宿主防御中的功能。他们将提供有关这种酶功能的新信息，目前人们对此知之甚少。这些研究将为肺部炎症和先天免疫的调节提供新的见解。

DESCRIPTION (provided by applicant): The broad goal of this application is to understand the biological function(s) of an enzyme termed secretory group V phospholipase A2 (sPLA2), particularly as it pertains to control of infections and pulmonary inflammation. Group V sPLA2 is prominently expressed in mast cells and macrophages, cells that are critical for sensing harmful organisms at their sites of entry into the body and in generating the acute inflammatory response that is essential for efficient clearing and killing of these pulmonary pathogens. Group V sPLA2 regulates the generation of leukotrienes and prostaglandins in both mast cells and macrophages in response to stimuli that are surrogates for invading pathogens, namely zymosan, derived from yeast cell walls, and agonists of toll-like receptor (TLR)-2. Our early studies indicate that the enzyme regulates phagocytosis and killing of the yeast Candida albicans in pulmonary macrophages and activation of signaling molecules called mitogen-activated protein kinases in response to TLR2 stimulation of mast cells. The aims of this proposal are therefore to understand how group V sPLA2 regulates phagocytosis and killing of fungi; to understand how group V sPLA2 regulates TLR signaling in mast cells; and to determine the importance of the enzyme for generation of pulmonary inflammatory responses to invading microorganisms and their clearance from the host. To achieve these aims we will compare the generation of lipids and early signaling events following zymosan stimulation between macrophages that lack group V sPLA2 and normal macrophages. We will express normal and mutant forms of group V sPLA2 in macrophages to examine the relationship between the structure of the enzyme and its function. We will compare the generation of lipids and early signaling events in response to TLR2 stimulation between mast cells that lack group V sPLA2 and normal mast cells. We will study the subcellular location of group V sPLA2 in mast cells stimulated through TLR2. Finally, we will use mice that lack group V sPLA2 to study the relevance of these findings in models of fungal pulmonary infection. The lung is a major site of entry into the body for infectious organisms. The ability to mount an effective and appropriate inflammatory response to these organisms is essential for survival. The proposed studies will define the function of group V phospholipase A2 in host defense. They will provide new information on the function of this enzyme, which is presently poorly understood. These studies will provide new insight into the regulation of pulmonary inflammation and innate immunity.