LUNG COLLAGEN CROSSLINKING--BIOSYNTHESIS AND MATURATION

以前在这项赠款下进行的工作表明， 研究胶原合成和成熟的可行性， 正常大鼠皮肤、骨、肌腱和肺的体内标记 技术. 本申请提出扩展这些实施例。 对肺纤维化的有据可查的动物模型的研究， 气管内注射博莱霉素的大鼠，研究胶原蛋白 合成和成熟的受损，（前）纤维化肺。 我们 将专门测试的假设，羟基化的关键 参与胶原交联反应的赖氨酸残基 是纤维化肺胶原蛋白生物合成的关键步骤。 在来自几种动物模型的肺组织和 人类纤维化肺已经证明了 赖氨酸和增加的双官能席夫碱- 衍生的，在（前）纤维化（急性纤维化）中将DHLNL交联至HLNL 肺 同样，我们观察到， 慢性纤维化中完全羟基化三官能交联OHP 动物模型和人类肺部的对比。 因此，我们建议在这方面检查以下假设 建议：（i）增加的赖氨酸羟基化区分 （ii）在肺中从“正常胶原”分离“纤维化胶原”; 这种差异是由赖氨酰的活性增加介导的 （iii）一旦（预）纤维化肺中的羟化酶 肺中的交联的“纤维化胶原蛋白”不受 或者说，在生活中，或者说，在生活中， 主持人 体内标记和组织切片的组合， 将进行匀浆实验以检查这些 问题. 与人肺组织的相关研究，如 急性（ARDS、IRDS）和慢性（IPF）患者 肺纤维化将检查胶原蛋白的潜在机制， 在人类肺部疾病中的积累， 这些疾病的合理治疗的潜在新靶点。

Previous work performed under this grant has demonstrated the feasibility of studying collagen biosynthesis and maturation in skin, bone, tendon, and lungs of normal rats by in vivo labelling techniques. The present application proposes to extend these studies into a well documented animal model of pulmonary fibrosis, intra-tracheally injected bleomycin in the rat, to study collagen synthesis and maturation in the damaged, (pre)fibrotic lung. We will specifically test the hypothesis that hydroxylation of key lysine residues that take part in collagen crosslinking reactions is a critical step in the biosynthesis of fibrotic lung collagen. Parallel studies in lung tissue from several animal models and in human fibrotic lungs have demonstrated increased hydroxylation of lysine and an increased ratio of the difunctional Schiff base- derived, crosslink DHLNL to HLNL in (Pre)fibrotic (acute fibrosis) lungs. Similarly, we have observed an increased content of the fully hydroxylated trifunctional crosslink OHP in chronic fibrosis of both animal models and human lungs. Thus, we propose to examine the following hypotheses in this proposal: (i) that increased lysine hydroxylation distinguishes "fibrotic collagen" from "normal collagen" in the lung; (ii) that this difference is mediated by increased activity of lysyl hydroxylase in the (pre)fibrotic lung; and (iii) that once crosslinked, "fibrotic collagen" in the lung is not subject to turnover or breakdown, but rather will persist for the lifetime of the host. A combination of in vivo labelling and tissue slice and homogenate experiments will be performed to examine these questions. Correlative studies with human lung tissue, as available, from patients with acute (ARDS, IRDS) and chronic (IPF) lung fibrosis will examine the underlying mechanisms of collagen accumulation in human lung disease, and will perhaps identify potential new targets for rational therapy of these diseases.