外泌体经CHOP通路调控肺泡上皮细胞端粒酶活性的分子机制及对肺纤维化的影响

肺纤维化，尤其是特发性肺纤维化是一种慢性致死性疾病，目前无有效治疗手段。肺泡上皮细胞（AEC）损伤在其发生、发展中起着关键作用。端粒酶活性降低和过度的内质网应激（ERS）均可导致AEC损伤。我们前期的研究发现：①ERS下游转录因子CHOP是调控AEC端粒酶活性的重要靶点；②骨髓间充质干细胞（BMSCs）外泌体可抑制ERS中CHOP表达及恢复端粒酶活性，但机制不清。我们推测：BMSCs外泌体传递调控CHOP的miRNA，进而恢复AEC损伤时端粒酶活性，可为肺纤维化的治疗提供新途径。本项目拟在前述工作基础上，收集体外博来霉素刺激AEC与BMSCs共培养中的外泌体，筛选外泌体中调控CHOP表达的miRNA；构建候选miRNA基因敲除鼠，以验证及阐明外泌体在影响AEC端粒酶活性中的作用机制，为BMSCs外泌体治疗肺纤维化提供新的治疗靶点及治疗思路。

Pulmonary fibrosis, especially archetypal fibrotic lung disease, idiopathic pulmonary fibrosis , is a chronic lethal disorder without effective therapies. Alveolar epithelial cell injury plays a key role in its occurrence and development. Abnormal telomerase activity and excessive endoplasmic reticulum stress (ERS) cause damage to alveolar epithelial cells. Our previous research found that: 1. CHOP, a special transcription factor downstream of ERS, is an important target for regulating telomerase activity of epithelial cells; 2. Bone marrow mesenchymal stem cells (BMSCs) exosomes can inhibit the expression of CHOP in ERS and restore telomerase activity, but the mechanism is unclear. We speculate that BMSCs-derived exosomes can deliver miRNAs that regulate CHOP, and then restore the damaged telomerase activity in alveolar epithelial cells during ERS, which provide a new way for the treatment of pulmonary fibrosis. Based on the aforementioned work, this project intends to collect exosomes in vitro in which co-culture alveolar epithelial cells and BMSCs with stimulation of bleomycin, and screen miRNAs that regulate CHOP expression in exosomes; further construct candidate miRNA-specific knockout mice to verify and elucidate the mechanism of exosomes in telomerase activity of alveolar epithelial cells. This project intend to provide new therapeutic targets and treatment ideas for the treatment of pulmonary fibrosis with BMSCs exosomes, as well as a new theoretical basis for clinical transformation.