Organic dust epithelial PKC activation & airway disease

描述(由申请人提供)：接触有机粉尘是呼吸道疾病的原因之一，包括慢性阻塞性肺疾病(COPD)。多达20%的COPD病例可归因于职业性接触。在农村地区，接触粉尘的一个重要来源是猪舍。暴露在猪舍中的人会出现呼吸道炎症，并增加慢性阻塞性肺疾病的发病率。虽然猪舍粉尘中存在许多引起炎症的物质，包括内毒素，但导致COPD的实际机制尚未很好地确定。了解猪舍粉尘引起的呼吸道疾病的机制对于制定有针对性的治疗和预防策略具有重要意义。上皮细胞对吸入剂的反应是释放细胞因子，这些细胞因子招募和激活炎症细胞，并表达作为受体和配体的分子，以便与其他细胞相互作用。我们观察到猪舍粉尘提取物(HDE)在体外能增强人呼吸道上皮细胞蛋白激酶C(PKC)的激活，导致IL-8和IL-6的释放，并增加ICAM-1的表达，从而介导炎症细胞与呼吸道上皮细胞的黏附。利用小鼠鼻内暴露于HDE，我们观察到体内呼吸道上皮细胞PKC活性和炎症反应的增加。我们最近观察到，上皮细胞暴露于HDE会导致脂质介质溶血磷脂酸(LPA)的增加。用磷脂酶B灭活LPA可抑制HDE刺激的IL-6和IL-8的释放。猪舍粉尘诱导的LPA在引导呼吸道炎症中的作用尚不清楚。本研究的目的是明确猪舍粉尘激活上皮细胞PKC的机制以及PKC在限制设施工人慢性支气管炎相关呼吸道炎症中的作用，并确定猪舍粉尘相关的LPA在调节粉尘对PKC和炎症反应的影响中的作用。1)确定HDE中激活上皮细胞PKC的因子(S)的生化性质和特异性，并确定HDE和这些因子激活的PKC同工酶。2)研究HDE相关的溶血磷脂酸(LPA)对HDE诱导的上皮细胞PKC活性和IL-8/IL-6释放的调节作用。3)明确HDE增强上皮细胞PKC在体外介导炎性细胞与呼吸道上皮细胞的募集和黏附的机制。4)利用暴露的动物模型，确定HDE如何在体内调节呼吸道上皮PKC激活和炎症反应，包括测试LPA的潜在作用。

DESCRIPTION (provided by applicant): Exposure to organic dusts is a cause of airway disease, including chronic obstructive pulmonary disease (COPD). As many as 20% of COPD cases are attributed to occupational exposures. In rural areas, an important source of dust exposure occurs in hog confinement barns. Persons exposed to hog barns have airway inflammation and an increased incidence of COPD. Although many substances are present in hog barn dust that induces inflammation including endotoxins, actual mechanisms leading to COPD are not well defined. Understanding mechanisms of hog barn dust-induced airway disease is relevant in developing both targeted treatment and prevention strategies. Epithelial cells respond to inhaled agents with the release of cytokines that recruit and activate inflammatory cells and expression of molecules that serve as receptors and ligands for interactions with other cells. We observed that hog barn dust extract (HDE) augments human airway epithelial protein kinase C (PKC) activation, resulting in IL-8 and IL-6 release and increased ICAM-1 expression, mediating inflammatory cell adhesion to airway epithelium in vitro. Using an intranasal exposure to HDE in mice, we observed an increase in airway epithelial PKC activation and inflammatory responses in vivo. We recently observed that epithelial cell exposure to HDE results in an increase of the lipid mediator lysophosphatidic acid (LPA). Treatment with phospholipase B to inactivate LPA inhibits HDE-stimulated IL-6 and IL-8 release. The role of LPA induced by hog barn dust in directing airway inflammation is not known. The objective of this proposal is to define mechanisms by which hog barn dust activates epithelial cell PKC and the role of PKC in airway inflammation associated with chronic bronchitis occurring in confinement facility workers and to determine the role of hog barn dust-related LPA, an important lipid mediator, in modulating dust effects on PKC and inflammatory responses. We will address our hypothesis with these specific aims: 1) Determine the biochemical nature and specific identity of factor(s) in HDE that activate epithelial cell PKC and identify the specific PKC isoenzymes activated by HDE and these factors. 2) Establish how HDE-associated lysophosphatidic acid (LPA) modulates HDE-induced epithelial cell PKC activity and IL-8/IL-6 release. 3) Identify mechanisms by which HDE augmentation of epithelial cell PKC In vitro mediates recruitment and adhesion of inflammatory cells to airway epithelium in vitro. 4) Determine how HDE modulates airway epithelial PKC activation and inflammatory responses in vivo utilizing an animal model of exposure, including testing the potential role of LPA.