Role of SFTPC in Pathogenesis of Interstitial Lung Disease

6.项目总结/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）， 治疗选择和诊断后3年的平均生存期。这种疾病的自然史 因为缺乏合适的动物模型。这种疾病的家族形式占较少 占IPF总病例的5%以上，特征为常染色体显性遗传，遗传率可变 与遗传修饰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-C外显子4和SP-CL 188 Q）提供了一个独特的机会， 家族性ILD的潜在途径。我们在细胞培养中的初步研究已经鉴定出独特的分子 复合物参与突变SP-C的检测和快速降解;此外，我们已经表明，细胞 表达突变SP-C并感染呼吸道合胞病毒的细胞积累错误折叠的SP-C， 比表达野生型蛋白的细胞更易受病毒诱导的细胞死亡的影响。这些钥匙 体外研究结果导致的核心假设，即环境压力叠加在SFTPC 突变导致错误折叠的细胞毒性SP-C的积累，反过来导致II型上皮细胞 细胞损伤/死亡，这是SFTPC相关家族性ILD的诱发事件。三个具体目标是 拟检验这一假设：具体目标1将检验ERAD（一种细胞保护途径） 快速鉴定和降解突变SP-C，防止细胞内积累，II型上皮细胞 凋亡和进展为ILD。具体目标2将检验病毒感染叠加在 Sftpc突变导致细胞毒性SP-C和II型上皮细胞凋亡的积累，反过来， 触发ILD发作或加速发病。具体目标3将检验抑制 突变体SP-C在体内的积累将阻止发展为ILD。本申请中提出的研究将 生成家族性IPF的第一个小鼠模型，并确定是否绝对需要环境损伤 对于疾病的发作;此外，该模型将允许测试体外研究结果的生物学相关性。 研究，特别是假设细胞毒性SP-C的积累驱动ILD的进展。鼠标 模型还将促进翻译研究的长期目标是（1）测试逆转的可行性 成人祖细胞移植的纤维化过程，（2）鉴定增强纤维化的新药 清除突变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）鉴定用于在无症状患者中早期检测疾病的候选基因。因此 总的来说，这项提案的长期目标是确定新的诊断和治疗策略， 目前的治疗标准是姑息治疗

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.