INTEGRIN-DEPENDENT T CELL-MEDIATED MECHANISMS OF PULMONARY FIBROSIS

描述(申请人提供)：肺纤维化是硬皮病、类风湿性关节炎、皮肌炎和多发性肌炎等自身免疫性风湿病患者致残和死亡的主要原因。肺纤维化的机制复杂且知之甚少，现代治疗方法也完全不够。尽管T细胞促进纤维化的机制仍有争议，但纤维化的严重程度和随后的肺功能下降往往与肺内T淋巴细胞的聚集有关。我们的观察指出，CC趋化因子CCL18可能在肺纤维化前T淋巴细胞聚集和纤维化中发挥中心作用。本研究的具体目的是研究肺T淋巴细胞的表型及其促纤维化作用的机制，并探讨CCL18是否能直接使正常人肺T细胞的表型向促纤维化倾斜。总体假设是肺纤维化是一种夸大的Treg介导的免疫抑制和抗炎反应的一部分。这项研究的特定假设是肺T细胞促进纤维化是因为它们的调节表型(Treg)。具体地说，我们假设这些肺T细胞是转化生长因子β+，类似于Th3和Tregs通过膜结合的转化生长因子β发挥作用。我们进一步假设，这些细胞以整合素依赖的方式持续存在于肺内，通过整合素依赖的机制分泌和激活转化生长因子β，将转化生长因子β保留在细胞表面，最终通过可溶性和膜结合的转化生长因子β刺激成纤维细胞，从而促进肺纤维化。为了评估这一假设的有效性，将解决以下具体目标： 1.明确CCL18肺过度表达模型中肺T淋巴细胞的促纤维化表型，导致其在肺内持续存在，并增加转化生长因子-β的产生、活化和细胞表面结合，特别是整合素的表达谱和作用。 2.确定含AV的整合素和含整合素的整合素是否促进肺T细胞和成纤维细胞之间的细胞间相互作用、增加转化生长因子β的产生和/或激活、T细胞与细胞表面的转化生长因子β的结合以及成纤维细胞刺激胶原的产生。 3.研究CCL18通过刺激肺T细胞表面转化生长因子β的表达、活化和细胞表面结合，以及含AV和含β2整合素的表达，直接调节肺T细胞向纤维化表型转化的能力。 这项研究的结果可能确定T淋巴细胞和CCL18作为未来自身免疫性风湿病患者抗纤维化治疗的靶点。

DESCRIPTION (provided by applicant): Pulmonary fibrosis is a major cause of disability and death in patients with autoimmune rheumatic diseases such as scleroderma, rheumatoid arthritis, dermatomyositis and polymyositis. The mechanisms of lung fibrosis are complex and poorly understood, and modern therapies are utterly inadequate. The severity of fibrosis and subsequent decline in lung function are frequently associated with pulmonary accumulation of T lymphocytes, although the mechanisms by which T cells promote fibrosis remain controversial. Our observations point to a possible central role of a CC chemokine CCL18 in pulmonary accumulation of profibrotic T lymphocytes and fibrosis. The Specific Objective of this study is to investigate the phenotypes and the mechanisms of the profibrotic action of pulmonary T lymphocytes, and to investigate whether CCL18 can directly skew the phenotype of normal human pulmonary T cells toward profibrotic. The Overall Hypothesis is that pulmonary fibrosis is part of an exaggerated Treg-mediated immunosuppressive and anti-inflammatory response. The Specific Hypothesis of this study is that pulmonary T cells promote fibrosis because of their regulatory phenotype (Treg). Specifically, we hypothesize that these pulmonary T cells are TGF-¿+, similar to Th3 and Tregs acting through membrane-bound TGF-¿. We further hypothesize that these cells facilitate pulmonary fibrosis by persisting in the lung in an integrin-dependent fashion, secreting and activating TGF-¿ through integrin-dependent mechanisms, retaining TGF-¿ on the cell surface, and ultimately stimulating fibroblasts through soluble and membrane-bound TGF-¿. To evaluate the validity of this hypothesis, the following Specific Aims will be addressed: 1. Define the profibrotic phenotype of pulmonary T lymphocytes leading to their prolonged persistence in the lungs and increased production, activation, and cell surface binding of TGF-¿ in the CCL18 pulmonary overexpression model, with a specific focus on the expression profile and role of integrins. 2. Determine whether aV-containing and ¿2-containing integrins facilitate cell-cell interactions between pulmonary T cell and fibroblasts, the increase in TGF-¿ production and/or activation, cell surface binding of TGF-¿ by T cells, and stimulation of collagen production by fibroblasts. 3. Investigate the ability of CCL18 to directly modulate the phenotype of pulmonary T cells toward profibrotic, by stimulating the expression, activation, and cell surface binding of TGF-¿, and expression of aV- containing and ¿2-containing integrins. The results of this study may identify T lymphocytes and CCL18 as targets for future antifibrotic therapies in patients with autoimmune rheumatic diseases.