Differential Roles of Chi3l1 and its receptors in COPD and IPF

摘要 COPD和纤维化疾病如特发性肺纤维化（IPF）具有显著不同的病理， 前者以组织损失为特征，后者以间质纤维化和过量基质沉积为特征。 然而，最近的研究强调了一个COPD患者亚组， 肺异常（ILA），并证明损伤和修复在这两种疾病中起关键作用。他们还 研究表明，TGF-β1是一种介体，在两种细胞中均失调，具有令人惊讶的驱动纤维化的能力， 同时增加组织损伤和细胞死亡。为了确定TGF-β1是否导致 肺气肿和/或纤维化，我们在10只近交遗传的小鼠上产生了肺靶向TGF-β1转基因（Tg）小鼠， 背景通过对这些小鼠进行计算机单倍型评估和表达微阵列分析，我们 确定了与TGF-β1诱导的纤维化或肺气肿相关的基因。有趣的是，这些TGF-β的研究， β1基因修饰子均导致了几丁质酶样蛋白Chi 3l 1及其受体的产生。 为了进一步了解Chi 3l 1轴在肺气肿和纤维化中的作用，最近的研究集中在 Chi 3l 1及其受体的生物学研究。这些研究表明：（1）Chi 3l 1在以下位点被诱导： 损伤和修复，其中它抑制损伤，同时促进修复，（2）在香烟烟雾（CS）诱导的肺气肿 和博来霉素反应，Chi 3l 1抑制上皮细胞死亡和组织破坏并驱动组织纤维化 （3）Chi 3l 1的作用是由两种不同的受体介导的，一种称为 壳聚糖体调节细胞死亡和CRTH 2驱动纤维增殖修复，（4）壳聚糖体具有一个 α亚基（IL-13 R α2）和2种不同的β亚基TMEM 219（TMEM）和半乳糖凝集素3（Gal 3）， 用于IL-13 R α2结合。我们最近的研究也强调了磷酸化和非磷酸化的作用。 Chi 3l 1的磷酸化形式，证明了壳聚糖体的组分受表观遗传的调节， 修改和突出Chi 3l 1轴和线粒体之间的关系。基于这些发现得出 本项目的总体假设：Chi 3l 1的差异表达、利用和/或磷酸化及其 受体在纤维化和肺气肿的不同结果的产生中起主要作用。解决 根据这一假设，我们将（目标#1）描述纤维化相关和肺气肿之间的关系， 暴露于CS后，基线时肺中相关的TGF-β1遗传修饰物和Chi 3l 1及其受体 或TGF-β1，并在纤维化和肺气肿的动物模型中，（目的#2）表征了该部位、机制和 通过细胞周期蛋白依赖性激酶（CDK），磷酸酶PP 2A & FAM 13 A，（目的#3）表征IL-13 R α2糖基化和IL-13 R α 2表观遗传修饰的重要性。 13 R α2和TMEM在Chi 3l 1的运输、结合和效应子应答中的作用（目的4）表征了 Chi 3l 1轴和线粒体之间的相互作用;特别是，线粒体如何调节Chi 3l 1轴 以及轴如何调节线粒体功能、动力学、生物发生、代谢和线粒体自噬。

ABSTRACT COPD and fibrotic disorders like idiopathic pulmonary fibrosis (IPF) have remarkably different pathologies with the former characterized by tissue loss and the latter by interstitial fibrosis and excess matrix deposition. However, recent studies highlighted a subgroup of patients with COPD with both emphysema and interstitial lung abnormalities (ILA) and demonstrated that injury and repair play critical roles in both disorders. They also demonstrated that TGF-β1 is a mediator that is dysregulated in both that has the surprising ability to drive fibrosis while augmenting tissue injury and cell death. To define the mechanisms that determine if TGF-β1 cause emphysema and or fibrosis, we generated lung-targeted TGF-β1 transgenic (Tg) mice on 10 inbred genetic backgrounds. Using In silico haplotype evaluations and expression microarray analysis on these mice, we have identified genes associated with TGF-β1-induced fibrosis or emphysema. Interestingly, the studies of these TGF- β1 genetic modifiers all led to the prototypic chitinase-like protein, chitinase 3-like-1 (Chi3l1) and its receptors. To further understand the role(s) of the Chi3l1 axis in emphysema and fibrosis, recent studies have focused on the biology of Chi3l1 and its receptors. These studies demonstrated that; (1) Chi3l1 is induced at sites of injury and repair where it inhibits injury while fostering repair, (2) In cigarette smoke (CS)-induced emphysema and bleomycin responses, Chi3l1 inhibits epithelial cell death and tissue destruction and drives tissue fibrosis respectively, (3) The effects of Chi3l1 are mediated by 2 different receptors, a multimeric complex called the chitosome that regulates cell death and CRTH2 which drives fibroproliferative repair, (4) The chitosome has one alpha subunit (IL-13Rα2) and 2 different β subunits, TMEM219 (TMEM) and galectin 3 (Gal3), which competes with TMEM for IL-13Rα2 binding. Our most recent studies have also highlighted phosphorylated and non- phosphorylated forms of Chi3l1, demonstrated that the components of the chitosome are regulated by epigenetic modifications and highlighted relationships between the Chi3l1 axis and mitochondria. These findings led to the overall hypothesis for this project: The differential expression, utilization and or phosphorylation of Chi3l1 and its receptors play major roles in the generation of the divergent outcomes of fibrosis and emphysema. To address this hypothesis, we will (Aim#1) characterize the relationships between the fibrosis-associated and emphysema- associated TGF-β1 genetic modifiers and Chi3l1 and its receptors in the lung at baseline, after exposure to CS or TGF-β1, and in animal models of fibrosis and emphysema, (Aim#2) characterize the site, mechanism and consequences of Chi3l1 activation/deactivation via cyclin-dependent kinase (CDK), the phosphatase PP2A & FAM13A, (Aim #3) characterize the importance of IL-13Rα2 glycosylation and epigenetic modifications of IL- 13Rα2 and TMEM in the trafficking, binding and effector responses of Chi3l1, (Aim #4) characterize the interactions between the Chi3l1 axis and mitochondria; specifically, how mitochondria regulate the Chi3l1 axis and how the axis regulates mitochondrial function, dynamics, biogenesis, metabolism, and mitophagy.