诱导性多功能干细胞来源的骨髓间充质干细胞对氧化应激导致的慢性肺损伤的治疗作用

Chronic obstructive pulmonary disease (COPD) with a prevalence of 9-10% is a leading cause of morbidity and mortality globally. COPD is a complex disease characterized by progressive airflow obstruction with alveolar wall destruction and chronic airway inflammation. The precise pathogenesis of COPD remains unclear; however, there are several mechanisms that are believed to play important roles: augmented chronic airway inflammation, oxidant/anti-oxidant and protease/anti-protease imbalances. Cigarette smoking is the major risk factor for COPD due to the presence of highly concentrated free radicals. There is unmet need for the development of newer effective therapies as current therapies have little effect on COPD progression but provide valuable symptomatic relief. One recent study has suggested that induced pluripotent stem cell-derived mesenchymal stem cells (iPSC-MSCs) can attenuate lung injury in allergen sensitized/challenged mouse model of asthma. However, the mechanisms how the iPSC-MSCs undergo the repair process are not well defined. Our preliminary data showed that mitochrondial transfer took place using cigarette smoke medium (CSM)-exposed human bronchial epithelial cells (BEAS-2B) in vitro. We hypothesize that energy metabolism will be modulated by cigarette smoke (CS) exposure over time leading to airway cell injury in vitro as well as in vivo. To verify the hypothesis, we will first characterize the cigarette smoke medium (CSM)-induced alterations in airway epithelial reactive oxygen species (ROS) production, expression of proinflammatory cytokines and apoptosis induction in relation to energy metabolism. Prolonged exposure to CS has been found to cause significant alterations in the metabolism of lipids with an increase in the concentrations of cholesterol and triglycerides in lung. The particular signaling pathways will be elucidated using selective inhibitors or activators in the absence or presence of iPSC-MSCs. We will further examine the in vivo effects of CS-exposed rats to compare lung injury development before and after treatments with iPSC-MSCs through examination of serological indicators and morphological changes in the airways and lung parachyma by biochemical, histological and immunohistchemical techniques. This work will provide mechanistic insight into the beneficial effects of iPSC-MSCs on oxidative stress-induced lung injury. The knowledge gained from this project will potentially lead to develop a novel effective therapeutic approach in the treatment of patients with chronic lung diseases from exposure to cigarette smoke or air pollution.

据流行病学统计，患病率为9-10%的慢性阻塞性肺病已成为全球疾病发生及死亡的重要原因。由于吸烟会释放大量高浓度自由基，所以成为慢性阻塞性肺病的主要危险因素。目前，一些治疗方法尚不能阻止慢性阻塞性肺病的发展，只能缓解部分可评估的症状，因此，有必要研发崭新有效的治疗方法以满足当前的需要。有报道指诱导性多功能干细胞来源的骨髓间充质干细胞（iPSC-MSCs） 能减轻过敏原致敏或激发小鼠哮喘模型中的肺损伤。但是，iPSC-MSCs如何完成修复肺损伤的机制尚不明确。我们假设，经过一段时间的香烟烟雾暴露，能量代谢会发生转变，以致气道细胞损伤。这项研究完成后将为iPSC-MSCs对氧化应激导致肺损伤的有效性提供机制研究基础。此项目获得的理论知识将可能为吸烟或者污染导致的慢性阻塞性肺病患者开发一种创新并且有效的治疗方法。

慢性阻塞性肺病（Chronic obstructive pulmonary disease，COPD）对全球人类健康造成严重威胁。由于带有高浓度的反应性自由基，因此，吸烟是COPD最常见的危险因素。气道炎症和气道重塑是COPD的重要病理特征，这可能是氧化应激引起的线粒体功能异常所造成的。至今为止，除了戒烟之外，现没有有效治疗COPD的疗法，因此，探究新型疗法间充质干细胞（mesenchymal stem cells ，MSCs）的作用机制，挽救氧化物引起的肺损伤是十分迫切的。这此项目中，我们研究了诱导性多功能干细胞来源的间充质干细胞（induced pluripotent stem cell-derived mesenchymal stem cells ，iPSC-MSCs）在大鼠吸烟模型中对氧化应激、炎症、细胞凋亡与增殖等各方面的作用，以及研究了干细胞的旁分泌因子在香烟溶液暴露的人上皮细胞体外模型的作用机制。我们进一步在体外人类气道平滑肌细胞（human airway smooth muscle cells，ASMCs）模型和体内臭氧暴露小鼠模型上，研究iPSC-MSCs对氧化应激引起到线粒体功能异常的作用。结果表明，iPSC-MSCs能显著减少香烟烟雾暴露引起的系统性8-isoprostane（氧化应激指标）和细胞因子引起的中心粒化学引诱物（cytokine-induced neutrophil chemoattractant-1， CINC-1，炎症指标）的升高，同时也改善香烟烟雾暴露引起的大鼠肺部肥大细胞和中心粒细胞浸润，细胞凋亡和增殖的失调。我们也证实了在iPSC-MSCs的条件培养液中，干细胞因子（stem cell factor，SCF）的缺失，将减少iPSC-MSCs的抗凋亡和促增殖能力，提示SCF作为iPSC-MSCs旁分泌的重要可能机制。我们发现，共培养时线粒体从iPSC-MSCs转移到香烟烟雾暴露引致损伤的人气道平滑肌细胞（human airway smooth muscle cells ，ASMSs）中，并通过减轻线粒体活性氧的产生，减少细胞凋亡，和影响线粒体膜电位（ΔΨm）等作用达到抗损伤的目的。进一步的研究证实，iPSC-MSCs减轻臭氧引起的小鼠肺部线粒体功能异常、气道高反应性和炎症反应。因此，我们的数据充分证实iPSC-MSC