REGULATION OF MATRIX-INDUCED GENES IN LUNG MACROPHAGES

慢性炎症和组织纤维化的特征是炎症细胞的涌入，炎症介质的积聚，以及细胞外基质(ECM)的周转和产生增加。越来越多的证据表明，ECM在影响炎症环境中发挥了积极作用。这项建议是申请人对肺部炎症和纤维化的兴趣的延伸，这是在她作为研究员进行了三年的基础研究期间，研究细胞外基质在炎症中的作用。细胞外基质成分透明质酸(HA)的片段聚集在肺部炎症中，诱导巨噬细胞表达几种趋化因子，这些趋化因子已被证明是慢性炎症和纤维化的重要介质。申请人先前的研究表明，炎症细胞因子干扰素-γ(IFN-γ)对HA诱导的趋化因子基因表达具有深远的影响。具体地说，干扰素-γ不仅下调某些HA诱导的促纤维化C-C趋化因子的基因表达，而且它还与HA协同作用，进一步诱导抗纤维化C-X-C趋化因子的亚群。本研究的目的是明确干扰素-γ在体外和体内调节HA诱导的肺泡巨噬细胞趋化因子表达的分子机制。这将通过(1)表征干扰素-γ抑制MIP-1α和MIP-1β基因表达的转录机制；(2)表征干扰素-γ与HA片段协同诱导MIG和IP-10基因表达的转录机制；以及(3)在干扰素-γ诱导的转基因小鼠系统中，使用博莱霉素肺炎症和纤维化模型在体内检测干扰素-γ对肺纤维化和趋化因子产生的影响。这些研究将在约翰·霍普金斯大学医学院由Hyun S.Shin医学博士赞助和指导下进行，Hyun S.Shin医学博士致力于巨噬细胞生物学的研究超过30年。约翰霍普金斯大学为这项提议的成功提供了必要的支持和智力刺激的环境。尽管这一建议是基于申请人先前的观察，但它是一条截然不同的研究路线，重点是体外和体内肺巨噬细胞中基质诱导基因的转录机制。这些研究应该允许申请者进一步提高和发展她的研究技能，并使她能够探索肺纤维化的基本分子机制，这可能导致新的治疗方法。

The hallmarks of chronic inflammation and tissue fibrosis are the influx of inflammatory cells, the accumulation of inflammatory mediators and the increased turnover and production of the extracellular matrix (ECM). There is a growing body of evidence implicating the active role of the ECM in influencing the inflammatory milieu. This proposal is an extension of the applicant's interest in pulmonary inflammation and fibrosis which arose during her three years of basic research, as a fellow, studying the role of the ECM in inflammation. Fragments of the extracellular matrix component hyaluronan (HA), which accumulate in lung inflammation, induce macrophage expression of several chemokines which have been shown to be important mediators of chronic inflammation and fibrosis. Previous research by the applicant revealed that the inflammatory cytokine interferon-gamma (IFN-gamma) exerts a profound effect on HA-induced chemokine gene expression. Specifically, IFN-gamma not only down regulates the gene expression of certain HA-induced pro- fibrotic C-C chemokines but it also synergizes with HA to further induce a subset of anti-fibrotic C-X-C chemokines. The purpose of this proposal is to define the molecular mechanisms by which IFN-gamma regulates HA-induced chemokine expression in alveolar macrophages both in vitro and in vivo. This will be pursued by (1) characterizing the transcriptional mechanisms by which IFN-gamma inhibits MIP-1alpha and MIP-1beta gene expression; (2) characterizing the transcriptional mechanisms by which IFN-gamma synergizes with HA fragments to induce MIG and IP-10 gene expression; and (3) examining the effect of IFN-gamma on lung fibrosis and chemokine production in vivo using the bleomycin model of lung inflammation and fibrosis in an IFN-gamma inducible transgenic mouse system. These studies are to be carried out at the Johns Hopkins University School of Medicine under the sponsorship and guidance of Hyun S. Shin, M.D. who has dedicated over 30 years to the study of macrophage biology. Johns Hopkins provides the supportive and intellectually stimulating environment necessary for the success of this proposal. Although this proposal is based on prior observations made by the applicant, it is a distinctly different line of investigation which focuses on the transcriptional mechanisms of matrix-induced genes in lung macrophages, both in vitro and in vivo. These studies should allow the applicant to further enhance and develop her research skills and enable her to pursue the basic molecular mechanisms of pulmonary fibrosis that might lead to novel treatment approaches.