TGFβ1 induces resistance of human lung myofibroblasts to cell death via down-regulation of TRPA1 channels

Background and Purpose TGF beta 1-mediated myofibroblast activation contributes to pathological fibrosis in many diseases including idiopathic pulmonary fibrosis (IPF), where myofibroblast resistance to oxidant-mediated apoptosis is also evident. We therefore investigated the involvement of redox-sensitive TRPA1 ion channels on human lung myofibroblasts (HLMFs) cell death and TGF beta 1-mediated pro-fibrotic responses. Experimental approach The effects of TGF beta 1 stimulation on TRPA1 expression and cell viability was studied in HLMFs derived from IPF patients and non-fibrotic patients. We also examined a model of TGF beta 1-dependent fibrogenesis in human lung. We used qRT-PCR, immunofluorescent assays, overexpression with lentiviral vectors and electrophysiological methods. Key Results TRPA1 mRNA, protein and ion currents were expressed in HLMFs derived from both non-fibrotic patient controls and IPF patients, and expression was reduced by TGF beta 1. TRPA1 mRNA was also down-regulated by TGF beta 1 in a model of lung fibrogenesis in human lung. TRPA1 over-expression or activation induced HLMF apoptosis, and activation of TRPA1 channel activation by H2O2 induced necrosis. TRPA1 inhibition following TGF beta 1 down-regulation or pharmacological inhibition, protected HLMFs from both apoptosis and necrosis. Lentiviral vector mediated TRPA1 expression was also found to induce sensitivity to H2O2 induced cell death in a TRPA1-negative HEK293T cell line. Conclusion and Implications TGF beta 1 induces resistance of HLMFs to TRPA1 agonist- and H2O2-mediated cell death via down-regulation of TRPA1 channels. Our data suggest that therapeutic strategies which prevent TGF beta 1-dependent down-regulation of TRPA1 may reduce myofibroblast survival in IPF and therefore improve clinical outcomes.

Automated summary

TGF beta 1 suppresses TRPA1 channels in human lung myofibroblasts, leading to resistance to TRPA1 agonist- and H2O2-mediated cell death. Therapeutic strategies targeting TGF beta 1-dependent down-regulation of TRPA1 may improve myofibroblast survival in IPF and clinical outcomes.