title: Monocyte-derived fibrocytes induce an inflammatory phenotype in airway smooth muscle cells.
abstract: BACKGROUND
  Infiltration of fibrocytes (FC) in the airway smooth muscle is a feature of asthma, but the pathological significance is unknown.
  
  
  OBJECTIVE
  We sought to explore whether FC modulate the phenotype of airway smooth muscle cells (ASMC) in asthmatic vs. control subjects.
  
  
  METHODS
  Fibrocytes were isolated from CD14+ monocytes from asthmatic and normal subjects. Proliferation of ASMC of asthmatic or normal subjects was analysed by (3) H-thymidine incorporation, cell number counting and Ki-67 expression after treatment of ASMC with FC-conditioned medium (FCCM) or co-culture with FC. ASMC-associated cytokines/chemokines implicated in asthma (TGF-β1, eotaxin, IL-6 and IL-8) were measured in co-culture or transwell culture of ASMC + FC by ELISA. Immunofluorescence staining was performed to localize these cytokines in ASMC. Cytokine secretion was measured in the transwell culture of ASMC + FC, where NF-κB-p65 or ERK1/2 in ASMC was silenced by siRNA. Contractile phenotype of ASMC in transwell culture was assessed by immunoblotting of α-smooth muscle actin (α-SMA) and myosin light chain kinase (MLCK).
  
  
  RESULTS
  Fibrocytes did not affect ASMC proliferation and expression of TGF-β1, eotaxin, α-SMA and MLCK; however, ASMC production of IL-8 and IL-6 was increased in the co-culture and transwell culture by FC. ASMC treated with FCCM were immunopositive for IL-8/IL-6 and produced more IL-8/IL-6. Furthermore, siRNA silencing of NF-κB-p65 or ERK1/2 in transwell cultures of asthmatic ASMC with normal subject FC decreased IL-8 and IL-6 production.
  
  
  CONCLUSIONS
  Fibrocytes promoted IL-8 and IL-6 production by ASMC, demonstrating a proinflammatory role for FC and a possible mechanism of the inflammatory phenotype in asthma.
authors.affiliation: Meakins-Christie Laboratories, McGill University, Montreal, QC, Canada; Department of Thoracic Medicine, Chang Gung Memorial Hospital, College of Medicine, Chang Gung University, Taipei, Taiwan.
authors.forename: T-Y
authors.initials: TY
authors.lastname: Lin
authors.forename: N
authors.initials: N
authors.lastname: Venkatesan
authors.forename: M
authors.initials: M
authors.lastname: Nishioka
authors.forename: S
authors.initials: S
authors.lastname: Kyoh
authors.forename: L
authors.initials: L
authors.lastname: Al-Alwan
authors.forename: C J
authors.initials: CJ
authors.lastname: Baglole
authors.forename: D H
authors.initials: DH
authors.lastname: Eidelman
authors.forename: M S
authors.initials: MS
authors.lastname: Ludwig
authors.forename: Q
authors.initials: Q
authors.lastname: Hamid
mesh_terms: D000199:Actins / Q000378:metabolism; D000328:Adult; D001249:Asthma / Q000175:diagnosis / Q000276:immunology / Q000378:metabolism* / Q000473:pathology*; D016022:Case-Control Studies; D002450:Cell Communication; D002454:Cell Differentiation; D002478:Cells, Cultured; D018920:Coculture Techniques; D024042:Collagen Type I / Q000378:metabolism; D005260:Female; D006801:Humans; D015850:Interleukin-6 / Q000096:biosynthesis; D016209:Interleukin-8 / Q000096:biosynthesis; D008297:Male; D008875:Middle Aged; D009000:Monocytes / Q000166:cytology / Q000378:metabolism*; D032389:Myocytes, Smooth Muscle / Q000378:metabolism*; D009219:Myosin-Light-Chain Kinase / Q000378:metabolism; D010641:Phenotype; D015398:Signal Transduction
chemical_list: C541116:ACTA2 protein, human; D000199:Actins; D024042:Collagen Type I; D015850:Interleukin-6; D016209:Interleukin-8; D009219:Myosin-Light-Chain Kinase
keywords: airway smooth muscle cells; asthma; fibrocytes; inflammation