PPARgamma Dysfunction in Sarcoidois

描述（由申请人提供）： 结节病是一种相对常见的炎性疾病，病因不明，发病率高。结节病炎症的特征在于巨噬细胞、辅助性T淋巴细胞和细胞因子（肿瘤坏死因子[TNF]、干扰素γ [IFN γ]等）之间的复杂相互关系，其导致肺和其他器官中肉芽肿的形成和不同程度的纤维化。流行病学数据（即家族聚集性、种族差异）强烈支持宿主易感性的遗传作用（即调控基因的多态性）。一种潜在的炎症调节因子是核转录因子，过氧化物酶体增殖物激活受体γ（PPARgamma）。这种最近描述的配体依赖性转录因子在单核细胞-巨噬细胞谱系的细胞中表达，这些细胞在结节病炎症中发挥关键作用。在自身免疫性和炎性疾病的实验模型中，PPARgamma激活拮抗炎性介质的表达和作用，已知其中许多在结节病中过表达。初步研究表明，在结节病的肺泡隔室中，PPARgamma活性和基因表达是缺乏的，而相反，炎性转录因子NF-κ B的活性上调。不足的PPARgamma活性可能通过不能抑制NF-κ B而使结节病的慢性炎性损伤永久化。基于这些观察，假设在结节病中PPARgamma调节功能障碍。本研究的具体目的是：（1）评价内源性PPARgamma mRNA（通过真实的时间RT-PCR）和蛋白质表达（通过免疫印迹和免疫细胞化学）在肺肉芽肿组织和支气管肺泡灌洗（BAL）细胞中;（2）研究BAL和外周血细胞对阳性刺激的体外PPARy应答。（白细胞介素4 [IL-4]、粒细胞-巨噬细胞集落刺激因子[GM-CSF]、佛波醇肉豆蔻酸酯[PMA]）;阴性（PPARgamma配体，IFN gamma）PPARgamma的调节剂;和（3）通过序列分析确定PPARgamma多态性是否与结节病相关。本研究将使用库存开放肺活检标本以及从结节病患者与健康对照组中获得的支气管镜新鲜标本的组合，以表征结节病中PPARgamma的状态。这些研究是第一个关注PPARgamma在结节病中的作用，初步数据强烈表明存在PPARgamma功能障碍。研究PPARgamma与结节病的关系对于更好地理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.