Abstract
Background: Inflammation-induced human airway smooth muscle cell (HASMC) proliferation contributes to hyperplasia in chronic lung diseases. Signaling pathways that link inflammation with proliferation are therapeutic targets. Endothelin-1 (ET1) signals via ETA and B-receptors (ETAR, ETBR) to perpetuate HASMC-associated inflammation.
Hypothesis: ET1 signaling links airway inflammation with HASMC proliferation.
Methods: HASMCs were ex vivo stimulated with inflammatory cytokines and analyzed for proliferation (cell counts, BrdU assay) and protein expression (ELISA, western blot). ETAR-selective (BQ123, ambrisentan), ETBR-specific (BQ788) and non-selective (macitentan, ACT-132577, bosentan) ET receptor antagonists (ERAs) were used.
Results: ET1 (≥10nM) and TNFα induced proliferation. TNFα effects were reduced by all ERAs, ET-1 effects by all except BQ788. TNFα induced ET1 and ETBR, ET1 induced GMCSF and IL6 expression. TNFα-induced GM-CSF was reduced by BQ123 and BQ788, TNFα-induced IL6 only by BQ123. Combined but not single GMCSF receptor (GMCSFRα)/IL6 blockade reduced TNFα- and ET-1-induced proliferation. Combined GMCSF/IL6/(1nM)ET-1 stimulation induced proliferation. Protein tyrosine kinase (PTK) and MAPkinase (MAPK) blockade reduced ET-1-induced proliferation, PTK inhibition and BQ123 had additional effects to GMCSFRα/IL6 blockade.
Conclusion: TNFα induces HASMC proliferation via ET-1 and ETAR/MAPK/IL6, ETAR/ETBR/MAPK/GMCSF, ETAR/PTK pathways. ETBR requires up-regulation by TNFα. This signaling network links airway inflammation with HASMC-proliferation and is sensitive to ERAs, which could target inflammation-induced airway smooth muscle hyperplasia.
- Copyright ©ERS 2015