IGF-II regulates lung fibrosis in scleroderma

摘要 器官纤维化是几种疾病不可逆转的终点，会导致器官衰竭。系统性硬化症(SSC) 是一种典型的多系统纤维性疾病，纤维化影响包括肺在内的多个器官。SSC有 在风湿性疾病和肺部受累中病死率最高的病例目前是 这种疾病患者的死亡。对于纤维化患者，唯一可用的治疗选择是器官 移植，这在临床上是不可能的，在必要的规模。多发性硬化性肝纤维化的特点 器官是破坏细胞外基质(ECM)的动态平衡，导致ECM积聚 部件和随后的器官衰竭。我们确定IGF-II是在SSc肺组织中过度表达的基因， 而在成人中，IGF-II仅在肝脏表达。胰岛素样生长因子-II在肺纤维化和SSc中的作用 仍未被探索。我们发现IGF-II在体外促进了原代肺成纤维细胞的纤维化，在体内 小鼠肺，并在人体组织中进行体外器官培养。我们还表明，IGF-II通过 增加ECM成分的表达，使MMP：TIMP平衡有利于纤维化环境，以及 诱导TGFb亚型表达，从而重现纤维化表型。我们假设IGF-II 通过结合IGF-IR/IR受体、激活转录因子促进纤维化 EGR-1和Sox9以及随后支架蛋白NEDD9的磷酸化。我们还建议 SSC肺组织中IGF-II的表达增加是表观遗传调控的结果。我们建议测试我们的 假说的具体目的如下：1)定义促进IGF-II介导的纤维化的因素 表型。具体地说，我们将确定转录因子Sox-9和Egr-1在协调 IGF-II的作用和支架蛋白NEDD9在介导对IGF-II的反应中的作用；2)鉴定 IGF-II受体通过阻断和抑制IGF-IR、IR和IGF-IIR对成纤维细胞的作用 受体酪氨酸激酶活性；3)检测SSC中IGF-II基因表达的调节 SSC肺成纤维细胞IGF-II mRNA双等位基因表达及其甲基化状态的检测 IGF-II-H19基因座。我们的发现将为SSC和其他疾病纤维化的发病机制提供新的见解 并将导致确定开发治疗方法的新靶点。我们的 方法将导致与人类疾病直接相关的发现，将推进机械论 了解胰岛素样生长因子-II的反应，以及以胰岛素样生长因子-II和/或其受体为靶点作为治疗药物的理论基础(S) 战略在SSC。

ABSTRACT Organ fibrosis is an irreversible endpoint of several diseases, leading to organ failure. Systemic sclerosis (SSc) is a prototypic multisystem fibrotic disease with fibrosis affecting multiple organs including the lung. SSc has the highest case fatality among rheumatic diseases and lung involvement is currently the leading cause of death of patients with this disease. The only available therapeutic option for patients with fibrosis is organ transplantation, which is clinically impossible on the scale necessary. The hallmark of fibrosis in multiple organs is the disruption of extracellular matrix (ECM) homeostasis, resulting in accumulation of ECM components and subsequent organ failure. We identified IGF-II as a gene overexpressed in SSc lung tissues, whereas in the adult IGF-II is only expressed in the liver. The role of IGF-II in pulmonary fibrosis and in SSc remains unexplored. We show that IGF-II promotes fibrosis in vitro in primary pulmonary fibroblasts, in vivo in mouse lungs, and ex vivo in human tissue in organ culture. We also show that IGF-II promotes its effects via increasing expression of ECM components, tipping the MMP:TIMP balance in favor of a fibrotic milieu, and inducing expression of TGFb isoforms, thus recapitulating the fibrotic phenotype. We hypothesize that IGF-II promotes fibrosis via engagement of hybrid IGF-IR/IR receptors, activation of the transcription factors Egr-1 and Sox9 and subsequent phosphorylation of the scaffold protein NEDD9. We also propose that increased expression of IGF-II in SSc lung is due to epigenetic regulation. We propose to test our hypothesis with the following specific aims: 1) Define the factors that promote the IGF-II-mediated fibrotic phenotype. Specifically we will determine the role of the transcription factors Sox-9 and Egr-1 in orchestrating the effects of IGF-II and the role of the scaffold protein NEDD9 in mediating the response to IGF-II; 2) Identify the receptors mediating the effects of IGF-II on fibroblasts by blocking IGF-IR, IR, and IGF-IIR and inhibiting receptor tyrosine kinase activity; and 3) Examine the regulation of IGF-II gene expression in SSc by examining if IGF-II mRNA in SSc lung fibroblasts shows biallelic expression and assessing the methylation status of the IGF-II—H19 locus. Our findings will provide new insights into the pathogenesis of fibrosis in SSc and other fibrotic disorders and will result in the identification of new targets for the development of therapies. Our approach will result in findings that are of direct relevance to the human disease, will advance mechanistic knowledge of the response to IGF-II, and a rationale for targeting IGF-II and/or its receptor(s) as a therapeutic strategy in SSc.