title: Brain-Derived Neurotrophic Factor Expression in Asthma. Association with Severity and Type 2 Inflammatory Processes.
abstract: 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.
authors.affiliation: Asthma Institute at University of Pittsburgh Medical Center, Division of Pulmonary, Allergy, and Critical Care Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania.
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Watanabe
authors.affiliation: Asthma Institute at University of Pittsburgh Medical Center, Division of Pulmonary, Allergy, and Critical Care Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania.
authors.forename: Merritt L
authors.identifier: http://orcid.org/0000-0002-9143-7712
authors.initials: ML
authors.lastname: Fajt
authors.affiliation: Asthma Institute at University of Pittsburgh Medical Center, Division of Pulmonary, Allergy, and Critical Care Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania.
authors.forename: John B
authors.initials: JB
authors.lastname: Trudeau
authors.affiliation: Asthma Institute at University of Pittsburgh Medical Center, Division of Pulmonary, Allergy, and Critical Care Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania.
authors.forename: Nipasiri
authors.initials: N
authors.lastname: Voraphani
authors.affiliation: Asthma Institute at University of Pittsburgh Medical Center, Division of Pulmonary, Allergy, and Critical Care Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania.
authors.forename: Haizhen
authors.initials: H
authors.lastname: Hu
authors.affiliation: Asthma Institute at University of Pittsburgh Medical Center, Division of Pulmonary, Allergy, and Critical Care Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania.
authors.forename: Xiuxia
authors.initials: X
authors.lastname: Zhou
authors.affiliation: Asthma Institute at University of Pittsburgh Medical Center, Division of Pulmonary, Allergy, and Critical Care Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania.
authors.forename: Fernando
authors.initials: F
authors.lastname: Holguin
authors.affiliation: Asthma Institute at University of Pittsburgh Medical Center, Division of Pulmonary, Allergy, and Critical Care Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania.
authors.forename: Sally E
authors.initials: SE
authors.lastname: Wenzel
mesh_terms: D000328:Adult; D001249:Asthma / Q000378:metabolism* / Q000473:pathology; D019208:Brain-Derived Neurotrophic Factor / Q000235:genetics / Q000378:metabolism*; D001980:Bronchi / Q000378:metabolism; D002478:Cells, Cultured; D005091:Exons; D005260:Female; D015870:Gene Expression; D006801:Humans; D018793:Interleukin-13 / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D020871:RNA Stability; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012720:Severity of Illness Index; D013183:Sputum / Q000378:metabolism; D055815:Young Adult
chemical_list: D019208:Brain-Derived Neurotrophic Factor; C578095:IL13 protein, human; D018793:Interleukin-13; D020033:Protein Isoforms; D012333:RNA, Messenger; C579455:BDNF protein, human
keywords: IL-13; asthma; brain-derived neurotrophic factor; epithelial cells; sputum