Eosinophil cationic protein stimulates TGF-β1 release by human lung fibroblasts in vitro

Eosinophilic inflammation and airway remodeling are features of asthma. Eosinophil cationic protein ( ECP) is released by activated eosinophils and transforming growth factor ( TGF)beta(1) has major functions in the fibrotic process. We therefore hypothesized that ECP stimulates TGF-beta(1) release by human lung fibroblasts. Fibroblasts in monolayer displayed a constitutive release of TGF-beta(1), which increased in presence of ECP ( 436 +/- 60 vs. 365 +/- 48 pg/ ml at 48 h; P< 0.01). mRNA expression of TGF-beta(1) was almost twofold in ECP- stimulated fibroblasts. ECP in threedimensional cultures stimulated both TGF-beta(1) release ( 180 +/- 61 vs. 137 +/- 54 pg/ ml; P< 0.01) and fibroblast- mediated collagen gel contraction ( 28 vs. 39% of initial gel area at 48 h; P< 0.001). ECP stimulates TGF-beta(1) release by human lung fibroblasts, suggesting a potential mechanism for eosinophils in the fibrotic response. This may be an important mechanism by which ECP promotes remodeling of extra cellular matrix leading to airway fibrosis in asthmatics.