INTEGRIN-DEPENDENT T CELL-MEDIATED MECHANISMS OF PULMONARY FIBROSIS

描述（由申请人提供）：肺纤维化是自身免疫性风湿性疾病（如硬皮病、类风湿性关节炎、皮肌炎和多发性肌炎）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，现代疗法完全不足。纤维化的严重程度和随后的肺功能下降通常与T淋巴细胞的肺部积聚有关，尽管T细胞促进纤维化的机制仍存在争议。我们的观察指出，CC趋化因子CCL 18可能在肺纤维化T淋巴细胞和纤维化的积累中发挥重要作用。本研究的具体目的是研究肺T淋巴细胞的促纤维化作用的表型和机制，并研究CCL 18是否可以直接使正常人肺T细胞的表型偏向促纤维化。总体假设是肺纤维化是过度Treg介导的免疫抑制和抗炎反应的一部分。本研究的具体假设是，肺T细胞由于其调节表型（Treg）而促进纤维化。具体来说，我们假设这些肺T细胞是TGF-<$+，类似于Th 3和TcR通过膜结合的TGF-<$发挥作用。我们进一步假设这些细胞通过以整合素依赖的方式持续存在于肺中，通过整合素依赖的机制分泌和激活TGF-β，将TGF-β保留在细胞表面，并最终通过可溶性和膜结合的TGF-β刺激成纤维细胞，从而促进肺纤维化。为了评价该假设的有效性，将讨论以下具体目标： 1.定义肺T淋巴细胞的促纤维化表型，导致其在肺中的持久性延长，并在CCL 18肺过度表达模型中增加TGF-β的产生、活化和细胞表面结合，特别关注整合素的表达谱和作用。 2.确定含α V和β 2的整合素是否促进肺T细胞和成纤维细胞之间的细胞-细胞相互作用，TGF-β产生和/或活化的增加，T细胞与TGF-β的细胞表面结合，以及成纤维细胞对胶原蛋白产生的刺激。 3.研究CCL 18通过刺激TGF-β的表达、活化和细胞表面结合以及含α V和β 2的整合素的表达，直接调节肺T细胞表型朝向促纤维化的能力。 这项研究的结果可能会确定T淋巴细胞和CCL 18作为未来抗纤维化治疗自身免疫性风湿性疾病患者的目标。

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.