【作者】 陈钢；

【导师】 熊先智；

【作者基本信息】 华中科技大学 ， 内科学（呼吸病学）， 2017， 博士

【摘要】 第一部分 TGF-β/BAMBI通路功能障碍可导致COPD患者外周血Th17/Treg 失衡*一直以来,TGF-β 家族的假受体(BMP and activin membrane-bound inhibitor,BAMBI)被认为能够抑制或调控转化生长因子β(transforming growth factor-β,TGF-β)信号通路。而且人们发现慢性阻塞性肺疾病(chronic obstructive pulmonary disease,COPD)患者的肺组织在体外感染后能够进一步上调BAMBI的表达水平。在本研究中,我们研究了 TGF-β/BAMBI通路是否与COPD相关。试验收集了来自27名不吸烟的健康对照者(healthy controls,HC),24例吸烟肺功能正常者(healthy smokers,HS)和29例吸烟的COPD稳定期患者的外周血标本。研究表明,与HC和HS组相比,COPD患者外周血的Th17/Treg比例升高,且BAMBI蛋白(在血浆中)和mRNA(在CD4+T细胞中)水平亦显著升高。我们首次发现BAMBI在人CD4+T细胞中表达,且呈现典型的膜结合型。COPD患者上调的血浆BAMBI水平不但与增加的血浆TGF-β1呈正相关,还与增加的Th17/Treg比例呈正相关。总之,TGF-β/BAMBI通路障碍可能导致炎症反应以及Th17/Treg失衡,这可能是吸烟者发展为COPD的新机制。第二部分香烟提取物通过假受体BAMBI参与Th17/Treg的调节在CD4+ T细胞或辅助性T细胞(helper T cells.Th)中,转化生长因子β1(transforming growth factor-β1,TGF-β1)对调节性 T 细胞(regulatory T cells,Treg)和Th17细胞的诱导足必不可少的。虽然TGF-β家族的假受体(BMP and activin membrane-bound inhibitor..BAMBI)能够以“变阻器”样的机制来调控TGF-β信号通路和自身免疫性关节炎小鼠模型,但BAMBI在人类Th17/Treg轴中的作用,特别是在香烟烟雾暴露时的活性还尚未阐明。在本研究中,我们通过流式细胞术对香烟提取物(cigarette smoke extract.CSE)刺激下的Treg和Th17分化特点进行了分析,同时还研究了CSE暴露对Smad2/3磷酸化(p-Smad2/β)和BAMBI表达的影响。我们的研究表明,在抗CD3/28抗体和TGF-β1的共同作用下,CSE暴露能够部分抑制Treg分化并促进Th17分化。同时,CSE能以剂量依赖性的方式抑制p-Smad2/3,这可能是由于伴随的BAMBI表达上调。总之,BAMBI能够作为分子开关来控制TGF-β信号强度和Th17/Treg平衡,因而BAMBI不仅可以作为一种生物标志,而且还能作为维持免疫耐受和吸烟诱导的免疫疾病的全新治疗靶点。更多还原

【Abstract】 Part Ⅰ TGF-β/BAMBI pathway dysfunction contributes to peripheral Th17/Treg imbalance in chronic obstructive pulmonary diseaseBMP and activin membrane-bound inhibitor(BAMBI)is postulated to inhibit or modulate transforming growth factor β(TGF-β)signaling.Furthermore,strong upregulation of BAMBI expression following in vitro infection of chronic obstructive pulmonary disease(COPD)lung tissue has been demonstrated.In this study,we investigated whether TGF-β/BAMBI pathway is associated with COPD.Blood samples were obtained from 27 healthy controls(HC),24 healthy smokers(HS)and 29 COPD patients.Elevated Thl7/Treg ratios,and increased levels of BAMBI protein and mRNA(in plasma and CD4+T cells respectively),were observed in COPD compared with HC and HS.BAMBI expression was first observed on human CD4+ T cells,with a typical membrane-bound pattern.The enhanced plasma BAMBI levels in COPD positively correlated with the increased plasma TGF-β1 levels and Th17/Treg ratio.Together.an impaired TGF-β/BAMBI pathway may promote the inflammation leading to Th17/Treg imbalance.which is a new mechanism in smokers who develop COPD.Part II Reciprocal regulation of Thl7/Treg cells by cigarette smoke extract through the pseudoreceptor BAMBIIn CD4+ T helper(Th)cells,transforming growth factor β1(TGF-β1)is indispensable for induction of both regulatory T(Treg)and Thl7 cells.Although BAMBI(BMP and activin membrane-bound inhibitor)has been identified as part of a rheostat-like mechanism for regulation of TGF-β signaling and autoimmune arthritis in mice model,the underlying activity of BAMBI in human Th17/Treg axis,especially during exposure to cigarette smoke,remains to be well elucidated.In this study,the characterization of Tregs and Th17 differentiation upon cigarette smoke extract(CSE)exposure were determined by flow cytometry.Furthermore,the effects of CSE on Smad2/3 phosphorylation and BAMBI expression in TCR-stimulated naive cells were also evaluated.Our study demonstrated that CSE exposure caused the partial suppression of Treg differentiation and the promotion of Th17 generation under stimulation by anti-CD3/28 antibodies plus TGF-β1.Meanwhile,cigarette smoke brought a dose-dependent inhibition of p-Smad2/3 which could arise from a concomitant enhancement of BAMBI expression.In conclusion,human BAMBI functions as a molecular switch to control TGF-(3 signaling strength and Thl7/Treg balance,which could be not only used as a biomarker,but also as a target of new treatment strategies for maintaining immune tolerance and for treatment of smoking-induced immune disorders.更多还原