PPAR-γ inhibits IL-13-induced collagen production in mouse airway fibroblasts

Interleukin-13 (IL-13) plays an important role in extracellular matrix production of airway remodeling in asthma. Activation of PPAR-γ has been shown to inhibit the occurrence of airway fibrosis in asthma, yet it remains unknown whether the effect of PPAR-γ on suppression of airway fibrosis is associated with the inhibition of IL-13 signaling. In the present study, primary cultured airway fibroblasts were stimulated with IL-13, and JAK inhibitor, PDGF receptor blocker and MEK inhibitor were applied to investigate the involvement of these pathways in IL-13-induced collagen production. Our results demonstrate that IL-13 dose- and time-dependently induced collagen production in primary cultured mouse airway fibroblasts; this effect was blocked by inhibition of JAK/STAT6 signal pathway. IL-13 also stimulated JAK/STAT6-dependent PDGF production, elevation of PDGF in turn activated ERK1/2 MAPK and caused collagen production. Activation of PPAR-γ by rosiglitazone reduced IL-13-induced collagen expression by suppression of STAT6-driven PDGF production. Our results indicate that activation of JAK/STAT6 signal and subsequent PDGF generation and ERK1/2 MAPK activation mediate IL-13-induced collagen production in airway fibroblasts. This study suggests that activation of PPAR-γ might be a novel strategy for the treatment of asthma partially by inhibition of airway fibrosis.