PPARgamma Dysfunction in Sarcoidois

描述(由申请人提供)： 结节病是一种病因不明、发病率较高的炎症性疾病。结节样炎症的特点是巨噬细胞、辅助性T淋巴细胞和细胞因子(肿瘤坏死因子、干扰素-γ等)之间的复杂相互关系，导致肉芽肿的形成和肺及其他器官不同程度的纤维化。流行病学数据(即家族聚集性、种族变异)有力地支持了宿主易感性的遗传作用(即调控基因的多态)。一种潜在的炎症调节因子是核转录因子，即过氧化物酶体增殖物激活受体γ(PPARGamma)。最近描述的配体依赖的转录因子在单核-巨噬细胞系的细胞中表达，这在结节样炎症中起着关键作用。在自身免疫和炎症性疾病的实验模型中，PPARγ激活拮抗炎症介质的表达和作用，其中许多已知在结节病中过度表达。初步研究表明，PPARγ活性和基因表达在结节病的肺泡室中缺乏，而炎性转录因子NF-kappaB的活性则上调。PPARγ活性不足可能通过未能抑制NF-kappaB而使结节病的慢性炎性损伤永久化。基于这些观察，我们推测PPAR伽马调节在结节病中是功能失调的。本研究的具体目的是：(1)通过实时定量RT-PCR检测肺肉芽肿组织和支气管肺泡灌洗(BAL)细胞中固有的PPARGamma mRNA和蛋白表达(通过免疫印迹和免疫细胞化学)；(2)体外研究BAL和外周血细胞对阳性(白介素4[IL-4]、粒细胞-巨噬细胞集落刺激因子[GM-CSF])、佛波酯(PMA)阳性刺激的PPARGamma反应；以及(3)通过序列分析确定PPARGamma基因多态是否与结节病相关。这项研究将使用银行开放肺活检标本以及支气管镜下从结节病患者和健康对照组获得的新鲜标本的组合来表征PPAR伽马在结节病中的状态。这些研究首次集中于PPAR-γ在结节病中的作用，初步数据强烈表明PPAR-γ功能障碍的存在。研究PPARGamma在结节病中的参与对于更好地了解疾病过程和产生新的治疗方法至关重要。

DESCRIPTION (provided by applicant): Sarcoidosis is a relatively common inflammatory disease of unknown etiology and significant morbidity. Sarcoid inflammation is characterized by complex interrelationships among macrophages, T-helper lymphocytes, and cytokines (tumor necrosis factor [TNF], interferon gamma [IFNgamma] and others) which lead to formation of granulomas and variable degrees of fibrosis in the lung and other organs. Epidemiologic data (i.e. familial clustering, racial variation) strongly support a genetic role for host susceptibility (i.e. polymorphisms of regulatory genes). A potential regulator of inflammation is the nuclear transcription factor, peroxisome proliferator-activated receptor gamma (PPARgamma). This recently described, ligand-dependent transcription factor is expressed in cells of the monocyte-macrophage lineage which play a critical role in sarcoid inflammation. In experimental models of autoimmune and inflammatory diseases, PPARgamma activation antagonizes expression and actions of inflammatory mediators, many of which are known to be overexpressed in sarcoidosis. Preliminary studies indicate that PPARgamma activity and gene expression are deficient in the alveolar compartment of sarcoidosis while in contrast, activity of the inflammatory transcription factor, NF-KappaB is upregulated. Insufficient PPARgamma activity may perpetuate the chronic inflammatory injury of sarcoidosis by failing to repress NF-KappaB. Based on these observations, it is hypothesized that PPARgamma regulation is dysfunctional in sarcoidosis. The specific aims of this study are to: (1) Evaluate intrinsic PPARgamma mRNA (by real time RT-PCR) and protein expression (by immunoblotting and immunocytochemistry) in pulmonary granuloma tissue and bronchoalveolar lavage (BAL) cells; (2) Investigate in vitro PPARgamma responses of BAL and peripheral blood cells to challenge with positive (interleukin 4 [IL-4], granulocyte-macrophage colony stimulating factor [GM-CSF]), phorbol myristate acetate [PMA]); and negative (PPARgamma ligands, IFNgamma) regulators of PPARgamma; and (3) Determine by sequence analysis whether PPARgamma polymorphisms are associated with sarcoidosis. The study will use a combination of banked open-lung biopsy specimens as well as bronchoscopically obtained fresh specimens from sarcoidosis patients vs healthy controls to characterize the status of PPARgamma in sarcoidosis. These studies are the first to focus upon the role of PPARgamma in sarcoidosis and preliminary data strongly suggest the presence of PPARgamma dysfunction. Investigation of PPARgamma involvement in sarcoidosis will be critical to better understanding the disease process and to generating novel approaches to therapy.