Role of SFTPC in Pathogenesis of Interstitial Lung Disease

6.项目摘要/摘要 特发性肺纤维化(IPF)是一种慢性进行性间质性肺疾病(ILD)，没有有效的 治疗方案和确诊后平均生存时间为3年。这种疾病的自然病史很差。 由于缺乏合适的动物模型而被理解。家族性疾病所占比例较小 占IPF病例总数的5%以上，以常染色体显性遗传为特征，外显率可变 与遗传修饰物和环境因素的影响有关。基因突变(SFTPC) 编码表面活性蛋白C(SP-Cexon4和SP-CL188Q)为分子识别提供了独特的机会 家族性ILD的潜在途径。我们在细胞培养中的初步研究已经确定了独特的分子 参与检测和快速降解突变型SP-C的复合体；此外，我们已经证明细胞 表达突变型SP-C并感染呼吸道合胞病毒可积累错折叠的SP-C和ARE 比表达野生型蛋白的细胞更容易受到病毒诱导的细胞死亡的影响。这些关键字输入 体外研究结果导致了一个中心假设，即环境压力叠加在SFTPC上 突变导致错误折叠的细胞毒性SP-C堆积，进而导致II型上皮 细胞损伤/死亡是SFTPC相关家族性ILD的诱发事件。三个具体目标是 建议测试这一假设：特定目标1将测试ERAD(一种细胞保护途径)的假设 快速识别和降解突变体SP-C，防止细胞内堆积，II型上皮细胞 细胞凋亡，并进展为ILD。《特定目标2》将检验病毒感染叠加在 Sftpc突变导致细胞毒性SP-C积聚和II型上皮细胞凋亡，进而， 触发ILD的发病或加速发病。《特指目标3》将检验这一假说 突变的SP-C在体内的积累将阻止进展为ILD。本申请书中建议的研究将 建立第一个家族性IPF小鼠模型，并确定是否绝对需要环境伤害 用于疾病的发病；此外，该模型将允许测试来自体外的发现的生物学相关性 研究，特别是细胞毒性SP-C的积累推动进展为ILD的假说。鼠标 模型还将促进翻译研究，其长期目标是：(1)测试逆转的可行性 成体祖细胞移植的纤维化过程，(2)寻找新的药物来增强 清除突变的SP-C(以及潜在的其他致病突变蛋白)并预防受影响的ILD 小鼠，以及(3)识别用于无症状患者疾病早期检测的候选基因。因此， 总体而言，这项建议的长期目标是确定一种疾病的新诊断和治疗策略 目前的治疗标准是治标不治本。

6. PROJECT SUMMARY/ABSTRACT Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive interstitial lung disease (ILD) with no effective treatment options and a mean survival of 3 years after diagnosis. The natural history of the disease is poorly understood because of the lack of an appropriate animal model. Familial forms of the disease account for less than 5% of total IPF cases and are characterized by autosomal dominant inheritance with variable penetrance related to the influence of both genetic modifiers and environmental factors. Mutations in the gene (SFTPC) encoding surfactant protein C (SP-Cexon4 and SP-CL188Q) provide an unique opportunity to identify molecular pathways underlying familial ILD. Our preliminary studies in cell culture have identified unique molecular complexes involved in the detection and rapid degradation of mutant SP-C; further, we have shown that cells expressing mutant SP-C and infected with respiratory syncticial virus accumulate misfolded SP-C and are much more susceptible to viral-induced cell death than cells expressing the wild type protein. These key in vitro findings lead to the central hypothesis that environmental stress superimposed on a SFTPC mutation leads to accumulation of misfolded, cytotoxic SP-C that, in turn, results in type II epithelial cell injury/death, which is the inciting event in SFTPC-associated familial ILD. Three specific aims are proposed to test this hypothesis: Specific aim 1 will test the hypothesis that ERAD (a cytoprotective pathway) rapidly identifies and degrades mutant SP-C preventing intracellular accumulation, type II epithelial cell apoptosis, and progression to ILD. Specific aim 2 will test the hypothesis that viral infection superimposed on an Sftpc mutation leads to accumulation of cytotoxic SP-C and type II epithelial cell apoptosis that, in turn, triggers the onset of ILD or accelerates pathogenesis. Specific aim 3 will test the hypothesis that inhibiting accumulation of mutant SP-C in vivo will prevent progression to ILD. Studies proposed in this application will generate the first mouse model of familial IPF and determine if an environmental insult is absolutely required for onset of the disease; further, this model will permit testing of the biologic relevance of findings from in vitro studies, in particular the hypothesis that accumulation of cytotoxic SP-C drives progression to ILD. The mouse model will also facilitate translational studies with the long-term goals of (1) testing the feasibility of reversing the fibrogenic process by transplantation of adult progenitor cells, (2) identifying new drugs that enhance clearance of mutant SP-C (and, potentially, other disease-causing mutant proteins) and prevent ILD in affected mice, and (3) identifying candidate genes for early detection of disease in asymptomatic patients. Thus, the overall, long term-goal of this proposal is to identify novel diagnostic and treatment strategies for a disease in which the current standard of care is palliative.