title: Hypoxia exerts dualistic effects on inflammatory and proliferative responses of healthy and asthmatic primary human bronchial smooth muscle cells.
abstract: BACKGROUND
  For oxygen supply, airway wall cells depend on diffusion though the basement membrane, as well as on delivery by micro-vessels. In the asthmatic lung, local hypoxic conditions may occur due to increased thickness and altered composition of the basement membrane, as well as due to edema of the inflamed airway wall.
  
  
  OBJECTIVE
  In our study we investigated the effect of hypoxia on proliferation and pro-inflammatory and pro-angiogenic parameter production by human bronchial smooth muscle cells (BSMC). Furthermore, conditioned media of hypoxia-exposed BSMC was tested for its ability to induce sprout outgrowth from endothelial cells spheroids.
  
  
  METHODS
  BSMC were cultured in RPMI1640 (5% FCS) under normoxic (21% O₂) and hypoxic (1% and 5% O₂) conditions. Proliferation was determined by cell count and Western blot analysis for cyclin E and Proliferating Cell Nuclear Antigen (PCNA). Secretion of IL-6, IL-8, ENA-78 and VEGF-A was analyzed by ELISA. BSMC conditioned medium was tested for its angiogenic capacity by endothelial cell (EC)-spheroid in vitro angiogenesis assay.
  
  
  RESULTS
  Proliferation of BSMC obtained from asthmatic and non-asthmatic patients was significantly reduced in the presence of 1% O₂, whereas 5% O₂ reduced proliferation of asthmatic BSMC only. Hypoxia induced HIF-1α expression in asthmatic and non-asthmatic BSMC, which coincided with significantly increased release of IL-6, IL-8 and VEGF-A, but not ENA-78. Finally, endothelial sprout outgrowth from EC spheroids was increased when exposed to hypoxia conditioned BSMC medium.
  
  
  CONCLUSIONS
  Hypoxia had dualistic effects on proliferative and inflammatory responses of asthmatic and non-asthmatic BSMC. First, hypoxia reduced BSMC proliferation. Second, hypoxia induced a pro-inflammatory, pro-angiogenic response. BSMC and EC may thus be promising new targets to counteract and/or alleviate airway wall remodeling.
authors.affiliation: Pulmonary Cell Research, Department of Biomedicine, University of Basel, Basel, Switzerland.
authors.forename: Laura
authors.initials: L
authors.lastname: Keglowich
authors.affiliation: Sydney Medical School, The University of Sydney, Sydney, Australia.
authors.forename: Melissa
authors.initials: M
authors.lastname: Baraket
authors.affiliation: Pulmonary Cell Research, Department of Biomedicine, University of Basel, Basel, Switzerland ; Department of Pneumology, University Hospital Basel, Basel, Switzerland.
authors.forename: Michael
authors.initials: M
authors.lastname: Tamm
authors.affiliation: Pulmonary Cell Research, Department of Biomedicine, University of Basel, Basel, Switzerland.
authors.forename: Peter
authors.initials: P
authors.lastname: Borger
mesh_terms: D000328:Adult; D001485:Basement Membrane / Q000473:pathology*; D015153:Blotting, Western; D001980:Bronchi / Q000503:physiopathology*; D002452:Cell Count; D049109:Cell Proliferation / Q000502:physiology*; D002478:Cells, Cultured; D054365:Chemokine CXCL5 / Q000378:metabolism; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D000860:Hypoxia / Q000503:physiopathology*; D015850:Interleukin-6 / Q000378:metabolism; D016209:Interleukin-8 / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D032389:Myocytes, Smooth Muscle / Q000502:physiology*; D010100:Oxygen / Q000378:metabolism*; D018874:Spheroids, Cellular / Q000378:metabolism; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism
chemical_list: C486263:CXCL5 protein, human; D054365:Chemokine CXCL5; D015850:Interleukin-6; D016209:Interleukin-8; D042461:Vascular Endothelial Growth Factor A; D010100:Oxygen