PPAR-γ通过NF-κB通路调控哮喘气道炎症启动因子TSLP的分子机制研究

Chronic allergic asthma is characterized by Th2-typed inflammation, and contributes to airway remodeling and the deterioration of lung function. Thymic stromal lymphopoietin (TSLP) is implicated in airway inflammatory diseases such as asthma. For example, mice that express a lung-specific TSLP transgene develop a spontaneous airway inflammatory disease with characteristic features found in human asthma. TSLP has been shown to be necessary and sufficient for the development of airway inflammation in mice. Elevated levels of TSLP mRNA were found in the airway epithelium from asthmatics.We previously showed elevated TSLP mRNA levels and protein expression from serum as well as induced sputum in asthmatics when compared with healthy individuals.We have found that TSLP expression is induced by inflammatory stimuli such as poly I:C. Notably, we found an remarkable decrease of TSLP mRNA levels and protein expression when 16HEB cells co-treated with poly I:C and Peroxisome proliferator activated receptor-γ(PPAR-γ) agonist rosiglitazone, Which is from a family of nuclear hormone receptors with multiple functions. We then treat the athsma mice model with rosiglitazone. Interestingly, both airway inflammation and TSLP level significantly deccreased when the mice treat with rosiglitazone. The expression of P65, a regulator factor of NF-kB signal pathway, was found decreased in airway epithelial cells. Furthermore, we found a repress TSLP gene expression when 16HEB cells co-treated with poly I:C and NF-kB inhibitor BAY-11 7082. Taken together, we hypothesise that PPAR-γ agonist repress TSLP gene expression potential mediated by NF-κB pathway in athsma. To achieve this hypothesis,we planned the project as following:1.Correlation analysis of PPAR-γ expression in airway epithelial cells with the severity; 2.The PPAR-γ agonists repress poly I:C-mediated TSLP gene expression through inhibition of NFκB, not through direct binding to the TSLP gene promoter. 3. Mice targeted deletion of PPAR-γ gene, homozygote or heterozygote, are physiologically involved in athsma development. These findings would give us a new insight of athsma mechanism,as well as a furture intervention target for athsma patients.

胸腺基质淋巴细胞生成素（TSLP）是哮喘气道炎症启动和维持的关键因子。我们的前期研究发现哮喘患者血浆和诱导痰中TSLP浓度较正常人显著升高，且与哮喘严重程度呈正相关。PPAR-γ激动剂罗格列酮能显著抑制哮喘小鼠模型血浆和诱导痰中TSLP的浓度，及肺组织NF-κB 的表达。罗格列酮和NF-κB 抑制剂均能抑制poly I:C刺激气道上皮细胞表达TSLP。由此我们提出本项目假设：NF-κB可能介导了PPAR-γ信号通路的激活，从而抑制气道上皮细胞分泌TSLP，抑制哮喘气道炎症的发生发展。为证实该假说，项目拟研究：⑴PPAR-γ在哮喘气道上皮细胞的表达与哮喘严重程度的相关性；⑵ PPAR-γ信号通路激活是否抑制了NF-kB与TSLP启动子的结合及转录启动；⑶ PPAR-γ基因敲除小鼠哮喘模型的表型。为哮喘的发病机制提出新理论，寻找新的干预方法

项目的背景：.TSLP是哮喘气道Th2型炎症启动和维持的关键因子， PPAR-γ及其激动剂具有抗炎和免疫调节作用。临床病例报道服用PPAR-γ激动剂有益于控制哮喘症状。我们假设：NF-κB可能介导了PPAR-γ信号通路的激活，从而抑制气道上皮细胞分泌TSLP，抑制哮喘气道炎症的发生发展。.主要研究内容、重要结果、关键数据：.本研究显示了哮喘患者血浆及诱导痰TSLP表达明显增加，与肺功能显著负相关。随着病情程度的增加，血浆及诱导痰TSLP表达明显增加。血浆中TSLP水平与诱导痰中TSLP水平显著相关。诱导痰中TSLP水平与嗜酸性粒细胞百分数及绝对计数显著正相关。罗格列酮可以抑制Poly I:C诱导的16HBE TSLP 的表达，这种抑制作用能够被PPAR-γ拮抗剂GW9662所拮抗，提示罗格列酮通过PPAR-γ通路发挥这种抑制作用。NF-κB抑制剂Bay 11-7082能够抑制Poly I:C诱导的16HBE TSLP 基因的表达，提示抑制NF-κB通路可以抑制TSLP的表达。罗格列酮可以抑制哮喘小鼠气道上皮细胞TSLP的高表达，降低哮喘小鼠的气道炎症及气道高反应性，降低Th2型细胞因子IL-4分泌和肺泡灌洗液的嗜酸细胞数量，提示罗格列酮可能通过抑制TSLP的表达来调控哮喘气道炎症的。罗格列酮可以抑制哮喘小鼠气道上皮细胞的NF-κB活性，结合细胞学实验提示可能通过抑制NF-κB活性来调控TSLP的表达。.我们通过采集临床、功能学、炎症等特征资料和抗人细胞因子抗体芯片检测了TSLP等20种血清细胞因子。基于PCA的层次聚类则识别出3个内因型。识别出一型以系统性炎症和症状较重为特征的哮喘内因型，增高的VEGF、leptin以及降低sRAGE可能参与了该哮喘内因型的系统炎症。.在研究中，我们还发现TSLP可能有双重免疫调节作用。我们发现HDM和 长链TSLP可以破坏屏障功能，短链TSLP和1,25 D3预处理可以抑制HDM所导致的哮喘性气道上皮屏障的破坏，同时在体内，短链TSLP和1,25 D3预处理可以改善HDM所致的哮喘。我们的实验强调了区分短链TSLP和长链TSLP的不同表达形式和生物学特性的重要性。此外,我们的结果表明短链TSLP和1,25 D3可能可以作为个性化治疗哮喘的一种新的药物。.科学意义： 发表SC收录论著2篇，会议论文1篇。.