Chitinase1 as a Biomarker and Therapeutic Target in Scleroderma Lung Disease

描述（由申请人提供）：壳三糖苷酶（几丁质酶1; Chit 1）是糖基水解酶18（GH 18）基因家族的成员，是人体中主要的真几丁质酶。它可以在正常个体的循环中以可检测的量发现，并且在以炎症、组织重塑和/或纤维化为特征的多种疾病中进一步增加，所述疾病包括细菌或真菌感染、溶酶体贮积病（戈谢病）、结节病和间质性肺病。然而，Chit 1的效应器功能尚未被定义，其 在这些疾病的发病机理中的作用尚未阐明。为了开始确定Chit 1在肺损伤和修复中的体内作用，我们表征了硬皮病（SSc）患者循环Chit活性的水平，并开始研究新产生的Chit 1无效突变小鼠中博莱霉素诱导的反应（Chit 1-/-），肺靶向Chit 1过表达转基因小鼠（Chit 1 Tg）和人源化Chit 1细菌人工染色体（BAC）小鼠（HBAC-Chit），所述小鼠含有人Chit 1及其在鼠Chit 1-/-背景上的调节序列。使用酵母双杂交试验，我们还确定了Chit 1结合的潜在伴侣/受体。这些研究表明：（a）循环Chit 1活性水平在SSc患者中增加，其中它们与间质性肺病（SSc-ILD）的存在和严重程度相关;（B）博来霉素攻击后，Chit 1在巨噬细胞和肺泡II型细胞中被诱导;和（c）与野生型（WT）对照相比，博来霉素诱导的纤维化在Chit 1-/-小鼠中显著改善，但在Chit 1 Tg小鼠中增强。他们还证明Chit 1增强TGF-β 1诱导的成纤维细胞增殖、受体表达以及经典和非经典信号传导，同时与TGF-β受体相关蛋白1（Tgfbrap 1）结合。这些发现使我们假设Chit 1是SSc-ILD患者的生物标志物，也是SSc-ILD患者的治疗靶点。这些研究还表明，Chit 1介导其纤维化作用，至少部分是通过其与Tgfbrap 1相互作用增强TGF-β 1反应的能力。为了验证这些假设，本项目的研究将使用体内、体外和翻译方法：1。定义循环Chit 1的水平 和Chit 1生物活性及其作为SSc生物标志物的作用。2.确定Chit 1在博来霉素和IL-13诱导的纤维化发病机制中的作用。3.定义Chit 1用于增加组织纤维化的机制。4.定义Chit 1与Tgfbrap 1的相互作用，以及这种相互作用在Chit 1生物效应发病机制中的作用。

DESCRIPTION (provided by applicant): Chitotriosidase (chitinase 1; Chit1), a member of the glycosyl hydrolase 18 (GH18) gene family, is the major true chitinase in humans. It can be found in detectable quantities in the circulation of normal individuals and is further increased in a variety of diseases characterized by inflammation, tissue remodeling and/or fibrosis including bacterial or fungal infections, lysosomal storage diseases (Gaucher's), sarcoidosis, and interstitial lung diseases. However, the effector functions of Chit1 have not been defined, and its roles in the pathogenesis of these diseases have not been elucidated. To begin to define the in vivo roles of Chit1 in pulmonary injury and repair, we characterized the levels of circulating Chit activity in patients with Scleroderma (SSc) and have begun to investigate the bleomycin-induced responses in newly generated Chit1 null mutant mice (Chit1-/-), lung-targeted Chit1 overexpressing transgenic mice (Chit1 Tg), and humanized Chit1 bacterial artificial chromosome (BAC) mice (HBAC-Chit) that contain human Chit1 and its regulatory sequences on a murine Chit1-/- background. Using yeast two hybrid assays, we have also identified potential partners/receptors that Chit1 binds to. These studies demonstrate that (a) the levels of circulating Chit1 activity are increased in patients with SSc where they correlate with the presence and severity of interstitial lung disease (SSc-ILD); (b) Chit1 is induced in macrophages and alveolar type II cells after bleomycin challenge; and (c) bleomycin-induced fibrosis is significantly ameliorated in Chit1-/- mice, but enhanced in Chit1 Tg mice compared to wild type (WT) controls. They also demonstrate that Chit1 augments TGF-�1-induced fibroblast proliferation, receptor expression and canonical and non-canonical signaling while binding to TGF-� receptor associated protein-1 (Tgfbrap1). These findings led us to hypothesize that Chit1 is a biomarker of and also a therapeutic target in SSc-ILD patients. These studies also suggest that Chit1 mediates its fibrotic effects, at least in part, via its ability to augment TGF-�1 responses by interacting with Tgfbrap1. To test the hypotheses, the studies in this project will use in vivo and in vitro and translational approaches to: 1. Define the levels of circulating Chit1 and Chit1 bioactivity and their roles as biomarkers in SSc. 2. Define the roles of Chit1 in the pathogenesis of bleomycin- and IL-13-induced fibrosis. 3. Define the mechanisms that Chit1 uses to augment tissue fibrosis. 4. Define the interaction of Chit1 with Tgfbrap1 and the role(s) of this interaction in the pathogenesis of the biologic effects of Chit1.