title: Rhinoviral stimuli, epithelial factors and ATP signalling contribute to bronchial smooth muscle production of IL-33.
abstract: BACKGROUND
  Bronchial smooth muscle cells (BSMCs) from severe asthmatics have been shown to overexpress the Th2-driving and asthma-associated cytokine IL-33. However, little is known regarding factors involved in BSMC production of IL-33. Rhinovirus (RV) infections cause asthma exacerbations, which exhibit features of Th2-type inflammation. Here, we investigated the effects of epithelial-derived media and viral stimuli on IL-33 expression in human BSMCs.
  
  
  METHODS
  Primary human BSMCs from healthy (n = 3) and asthmatic (n = 3) subjects were stimulated with conditioned media from primary human bronchial epithelial cells (BECs), double-stranded (ds)RNA, dsRNA/LyoVec, or infected with RV. BSMCs were also pretreated with the purinergic receptor antagonist suramin. IL-33 expression was analysed by RT-qPCR and western blot and ATP levels were determined in cell supernatants.
  
  
  RESULTS
  RV infection and activation of TLR3 by dsRNA increased IL-33 mRNA and protein in healthy and asthmatic BSMCs. These effects were inhibited by dexamethasone. BSMC expression of IL-33 was also increased by stimulation of RIG-I-like receptors using dsRNA/LyoVec. Conditioned media from BECs induced BSMC expression of IL-33, which was further enhanced by dsRNA. BEC-derived medium and viral-stimulated BSMC supernatants exhibited elevated ATP levels. Blocking of purinergic signalling with suramin inhibited BSMC expression of IL-33 induced by dsRNA and BEC-derived medium.
  
  
  CONCLUSIONS
  RV infection of BSMCs and activation of TLR3 and RIG-I-like receptors cause expression and production of IL-33. Epithelial-released factor(s) increase BSMC expression of IL-33 and exhibit positive interaction with dsRNA. Increased BSMC IL-33 associates with ATP release and is antagonised by suramin. We suggest that epithelial-derived factors contribute to baseline BSMC IL-33 production, which is further augmented by RV infection of BSMCs and stimulation of their pathogen-recognising receptors.
authors: Division of Respiratory Immunopharmacology, Department of Experimental Medical Science, BMC D12, Lund University, 221 84, Lund, Sweden. jenny.calven@med.lu.se.
authors: Jenny
authors: J
authors: Calvén
authors: Division of Respiratory Immunopharmacology, Department of Experimental Medical Science, BMC D12, Lund University, 221 84, Lund, Sweden. hamid.akbarshahi@med.lu.se.
authors: Hamid
authors: H
authors: Akbarshahi
authors: Division of Respiratory Immunopharmacology, Department of Experimental Medical Science, BMC D12, Lund University, 221 84, Lund, Sweden. mandy.menzel@med.lu.se.
authors: Mandy
authors: M
authors: Menzel
authors: Department of Pneumology, University Hospital Freiburg, Killianstrasse 5, 79106, Freiburg, Germany. korcan.ayata@uniklinik-freiburg.de.
authors: Cemil Korcan
authors: CK
authors: Ayata
authors: Department of Pneumology, University Hospital Freiburg, Killianstrasse 5, 79106, Freiburg, Germany. marco.idzko@uniklinik-freiburg.de.
authors: Marco
authors: M
authors: Idzko
authors: Division of Respiratory Immunopharmacology, Department of Experimental Medical Science, BMC D12, Lund University, 221 84, Lund, Sweden. leif.bjermer@med.lu.se.
authors: Leif
authors: L
authors: Bjermer
authors: Division of Respiratory Immunopharmacology, Department of Experimental Medical Science, BMC D12, Lund University, 221 84, Lund, Sweden. lena.uller@med.lu.se.
authors: Lena
authors: L
authors: Uller
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism*; D001249:Asthma / Q000378:metabolism* / Q000821:virology; D001980:Bronchi / Q000166:cytology / Q000821:virology; D002478:Cells, Cultured; D017077:Culture Media, Conditioned / Q000737:chemistry; D000071457:DEAD Box Protein 58; D053487:DEAD-box RNA Helicases / Q000378:metabolism; D003907:Dexamethasone / Q000737:chemistry; D004848:Epithelium / Q000821:virology*; D006801:Humans; D007249:Inflammation / Q000378:metabolism; D000067596:Interleukin-33 / Q000378:metabolism*; D032389:Myocytes, Smooth Muscle / Q000378:metabolism* / Q000821:virology; D010850:Picornaviridae Infections / Q000378:metabolism / Q000821:virology; D012330:RNA, Double-Stranded / Q000378:metabolism; D011971:Receptors, Immunologic; D012229:Rhinovirus; D015398:Signal Transduction; D013498:Suramin / Q000737:chemistry; D018418:Th2 Cells / Q000166:cytology; D051196:Toll-Like Receptor 3 / Q000378:metabolism
chemical_list: D017077:Culture Media, Conditioned; C506536:IL33 protein, human; D000067596:Interleukin-33; D012330:RNA, Double-Stranded; D011971:Receptors, Immunologic; C495344:TLR3 protein, human; D051196:Toll-Like Receptor 3; D013498:Suramin; D003907:Dexamethasone; D000255:Adenosine Triphosphate; C452820:RIGI protein, human; D000071457:DEAD Box Protein 58; D053487:DEAD-box RNA Helicases