Brg1在糖皮质激素抑制哮喘气道上皮损伤修复中的作用机制与干预研究

Glucocorticoid (GC) is now recognized as the most important medicine for asthma treatment, but it still can not relieve clinical symptoms and further impairment of lung function completely. We previously demonstrated that GC inhibited the proliferation and repair of airway epithelium after injury of asthma. And the intervention to promote epithelial growth with Vitamin A is poor, suggesting that there exists other molecular mechanisms when GC treated asthma. It is paid more attention on chromatin remodeling based epigenetic mechanisms in asthma. Recently preliminary results showed that in asthma mice model, GC inhibited Brg1 expression of their airway epithelia; in Brg1 knockout asthma mice, the delayed repair of airway epithelial cells was observed when GC treated asthma mice, indicating that Brg1 may play a key role in GC induced side effects in asthma treatment. Here, we further apply asthma models in vivo and in vitro, to in-depth explore the epigenetic mechanism that Brg1 is combined with GC-GR, to mediate chromatin histone conformation, to increase GILZ expression, to inhibit the downstream MAPK-ERK signal, and thereby to affect the damage and repair of asthma airway epithelial cells. We also try to supply notoginsenoside R1 to enhance Brg1 that attenuates GILZ expression , to promote the repair of damage airway epithelial when GC treated asthma. This work will provide new ideas and methods for the development of new epigenetic medicines, the improvement of curative effect, and the recurrence reduction for asthma, which has an important clinical significance.

糖皮质激素（GC）是目前治疗哮喘最重要的药物，但仍不能彻底缓解其症状反复发作及肺功能进一步损害。项目组前期已证实GC可抑制哮喘气道上皮损伤后修复，用VitA干预效果不佳，提示GC治疗哮喘的副作用还存在其他机制。近年来，染色质重塑为主的表观遗传机制在哮喘研究中引起关注。预实验发现，GC可抑制哮喘鼠气道上皮中染色质重塑因子Brg1表达，尤其是在Brg1基因敲除鼠中观察到气道上皮修复延迟，提示Brg1在GC治疗哮喘所致副作用中可能起关键作用。本课题拟进一步利用哮喘体内外模型深入探究：Brg1与GC-GR结合，调控染色质组蛋白构象，促进GILZ表达增加，抑制下游MAPK-ERK信号而影响气道上皮损伤后修复的表观遗传机制；并试图在GC治疗哮喘时联合使用三七皂苷R1来增强Brg1与减弱GILZ表达，促进损伤的气道上皮修复，为开发哮喘新型表观遗传药物、提高哮喘疗效提供新思路和方法，具有重要意义。

糖皮质激素（GC）是目前哮喘治疗的一线药物，但仍不能完全解决哮喘反复发作、部分患者控制不佳及肺功能进一步损害等问题。项目组前期已证实GC可抑制哮喘气道上皮损伤后修复，用VitA干预效果不佳，提示GC治疗哮喘的副作用还存在其他机制。前期实验发现，GC可抑制哮喘鼠气道上皮中染色质重塑因子Brg1表达，尤其是在Brg1基因敲除鼠中观察到气道上皮修复延迟，提示Brg1在GC治疗哮喘所致副作用中可能起关键作用。基于以上问题，我们申请了该标书并在哮喘小鼠模型及细胞模型上进行了相关实验验证，结果发现在小鼠模型中敲除染色质重塑因子Brg1可减轻哮喘症状，减少气道上皮损伤，其机制可能是通过调控细胞紧密连接蛋白E-cadherin增强气道上皮细胞连接性促进哮喘气道上皮损伤修复；同时我们也发现小鼠模型中敲除Brg1可减少气道炎症，促进上皮损伤修复，其机制可能是通过调控PI3K/AKT/mTOR信号通路。我们在细胞模型中敲除Brg1基因发现气道上皮细胞增殖迁移能力明显增强，E-cadherin蛋白表达增多。利用三七皂苷R1干预GC治疗的哮喘小鼠和细胞，结果发现三七皂苷R1可以减轻GC抑制哮喘小鼠气道上皮损伤修复的副作用，在细胞模型中发现三七皂苷R1可以减少地塞米松（Dex）诱导的上皮细胞凋亡，同时减轻Dex对上皮细胞增殖迁移能力的抑制作用，其可能机制是通过减少Dex对GRβ的抑制作用，使MAPK信号通路的激活增加，进而改善Dex抑制哮喘气道上皮损伤修复的作用。本项目研究结果为开发哮喘靶向药物、减轻GC治疗哮喘的副作用提高哮喘疗效提供了新的思路和方法。