title: Suppression of epithelial signal transducer and activator of transcription 1 activation by extracts of Aspergillus fumigatus.
abstract: Aspergillus fumigatus (AF) is often pathogenic in immune-deficient individuals and can cause life-threatening infections such as invasive aspergillosis. The pulmonary epithelial response to AF infection and the signaling pathways associated with it have not been completely studied. BEAS-2B cells or primary human bronchial epithelial cells were exposed to extracts of AF and challenged with IFN-β or the Toll-like receptor 3 agonist double-stranded RNA (dsRNA). Cytokine release (B-cell activating factor of the TNF family [BAFF], IFN-γ-induced protein-10 [IP-10], etc.) was assessed. AF extract was separated into low-molecular-weight (LMW) and high-molecular-weight (HMW) fractions using ultra 4 centrifugal force filters to characterize the activity. Real-time PCR was performed with a TaqMan method, and protein estimation was performed using ELISA techniques. Western blot was performed to assess phosphorylation of signal transducer and activator of transcription 1 (STAT1). IFN-β and dsRNA induced messenger RNA (mRNA) expression of BAFF (350- and 452-fold, respectively [n = 3]) and IP-10 (1,081- and 3,044-fold, respectively [n = 3]) in BEAS-2B cells. When cells were pretreated with AF extract for 1 hour and then stimulated with IFN-β or dsRNA for 6 hours, induction of BAFF and IP-10 mRNA was strongly suppressed relative to levels produced by IFN-β and dsRNA alone. When compared with control, soluble BAFF and IP-10 protein levels were maximally suppressed in dsRNA-stimulated wells treated with 1:320 wt/vol AF extract (P < 0.005). Upon molecular size fractionation, a LMW fraction of AF extract had no measurable suppressive effect on IP-10 mRNA expression. However, a HMW fraction of the AF extract significantly suppressed IP-10 expression in BEAS-2B cells that were stimulated with dsRNA or IFN-β. When BEAS-2B cells were pretreated with AF extract and then stimulated with IFN-β, reduced levels of pSTAT1 were observed, with maximum suppression at 4 and 6 hours. Our results show that AF extracts suppressed expression of inflammatory cytokines in association with inhibition of the IFN-β signaling pathway and suppression of the formation of pSTAT1.
authors.affiliation: 1 Division of Otolaryngology-Head and Neck Surgery, Ann & Robert H. Lurie Children's Hospital of Chicago and the Northwestern University Feinberg School of Medicine, Chicago, Illinois.
authors.forename: Bharat
authors.initials: B
authors.lastname: Bhushan
authors.affiliation: 2 Division of Allergy and Immunology, Northwestern University Feinberg School of Medicine, Chicago, Illinois.|3 Department of Internal Medicine, Division of Respiratory Medicine and Allergology, Showa University School of Medicine, Tokyo, Japan.
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Homma
authors.affiliation: 2 Division of Allergy and Immunology, Northwestern University Feinberg School of Medicine, Chicago, Illinois.
authors.forename: James E
authors.initials: JE
authors.lastname: Norton
authors.affiliation: 4 Allergy and Immunology Research Center, Anhui Medical University, Anhui, China.
authors.forename: Quan
authors.initials: Q
authors.lastname: Sha
authors.affiliation: 5 Medical College of Wisconsin, Milwaukee, Wisconsin; and.
authors.forename: Jason
authors.initials: J
authors.lastname: Siebert
authors.affiliation: 6 Division of Allergy and Immunology, National Jewish Health, Denver, Colorado.
authors.forename: Dave S
authors.initials: DS
authors.lastname: Gupta
authors.affiliation: 1 Division of Otolaryngology-Head and Neck Surgery, Ann & Robert H. Lurie Children's Hospital of Chicago and the Northwestern University Feinberg School of Medicine, Chicago, Illinois.
authors.forename: James W
authors.initials: JW
authors.lastname: Schroeder
authors.affiliation: 2 Division of Allergy and Immunology, Northwestern University Feinberg School of Medicine, Chicago, Illinois.
authors.forename: Robert P
authors.initials: RP
authors.lastname: Schleimer
mesh_terms: D001232:Aspergillus fumigatus / Q000737:chemistry*; D002460:Cell Line; D045424:Complex Mixtures / Q000633:toxicity*; D016207:Cytokines / Q000235:genetics / Q000378:metabolism; D015536:Down-Regulation / Q000187:drug effects*; D004847:Epithelial Cells / Q000378:metabolism / Q000473:pathology; D006801:Humans; D018836:Inflammation Mediators / Q000378:metabolism*; D055732:Pulmonary Aspergillosis / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D020545:Respiratory Mucosa / Q000378:metabolism* / Q000473:pathology; D050794:STAT1 Transcription Factor / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects
chemical_list: D045424:Complex Mixtures; D016207:Cytokines; D018836:Inflammation Mediators; D012333:RNA, Messenger; D050794:STAT1 Transcription Factor; C494079:STAT1 protein, human
keywords: Aspergillus fumigatus; BAFF; IP-10; epithelial cells