Watanabe Tetsuya, Fajt Merritt L, Trudeau John B, Voraphani Nipasiri, Hu Haizhen, Zhou Xiuxia, Holguin Fernando, Wenzel Sally E
Asthma Institute at University of Pittsburgh Medical Center, Division of Pulmonary, Allergy, and Critical Care Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania.
Am J Respir Cell Mol Biol. 2015 Dec;53(6):844-52. doi: 10.1165/rcmb.2015-0015OC.
Brain-derived neurotrophic factor (BDNF), a member of the neurotrophin family, exists in several isoforms, which differentially impacts neuronal and immune cell survival and differentiation. The role of BDNF and its isoforms in asthma remains unclear. The objectives of this study were to compare the BDNF protein isoforms and specific splice variant expression in sputum and bronchoscopic samples from healthy control subjects and participants with asthma, and to relate these changes to findings in IL-13-stimulated human airway epithelial cells. Sputum and bronchoscopic samples from healthy control subjects and participants with asthma were evaluated for BDNF protein (ELISA and Western blot) and BDNF mRNA (gel and quantitative real-time PCR) in relation to asthma severity and type 2 inflammatory processes. BDNF mRNA was measured in cultured primary human airway epithelial cells after IL-13 stimulation. Total BDNF protein differed among the groups, and its mature isoform was significantly higher in sputum from subjects with severe asthma compared with healthy control subjects (overall P = 0.008, P = 0.027, respectively). Total BDNF was higher in those with elevated fractional exhaled nitric oxide and sputum eosinophilia. In vitro, IL-13 increased BDNF exon VIb splice variant and the ratio to BDNF common exon IX mRNA (P < 0.001, P = 0.003, respectively). Epithelial brushing exon VIb mRNA and total BDNF protein differed among the groups and were higher in subjects with severe asthma than in healthy control subjects (overall P = 0.01, P = 0.02, respectively). The mature BDNF isoform and the exon VIb splice variant are increased in human asthmatic airways. The in vitro increase in response to IL-13 suggests that type 2 cytokines regulate BDNF levels and activity in asthma.
脑源性神经营养因子（BDNF）是神经营养因子家族的成员之一，以多种异构体形式存在，对神经元和免疫细胞的存活与分化有不同影响。BDNF及其异构体在哮喘中的作用尚不清楚。本研究的目的是比较健康对照受试者和哮喘患者痰液及支气管镜样本中BDNF蛋白异构体和特定剪接变体的表达，并将这些变化与白细胞介素-13刺激的人气道上皮细胞中的发现相关联。对健康对照受试者和哮喘患者的痰液及支气管镜样本进行评估，检测与哮喘严重程度和2型炎症过程相关的BDNF蛋白（酶联免疫吸附测定和蛋白质印迹法）和BDNF信使核糖核酸（凝胶电泳和定量实时聚合酶链反应）。在白细胞介素-13刺激后，检测培养的原代人气道上皮细胞中的BDNF信使核糖核酸。各组之间总BDNF蛋白存在差异，与健康对照受试者相比，重度哮喘患者痰液中的成熟异构体显著更高（总体P分别为0.008和0.027）。呼出一氧化氮分数升高和痰液嗜酸性粒细胞增多的患者中总BDNF更高。在体外，白细胞介素-13增加了BDNF外显子VIb剪接变体及其与BDNF共同外显子IX信使核糖核酸的比例（分别为P<0.001和P = 0.003）。各组之间上皮刷检外显子VIb信使核糖核酸和总BDNF蛋白存在差异，重度哮喘患者高于健康对照受试者（总体P分别为0.01和0.02）。成熟的BDNF异构体和外显子VIb剪接变体在人类哮喘气道中增加。体外对白细胞介素-13的反应增加表明2型细胞因子调节哮喘中BDNF的水平和活性。
