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

Background and Purpose TGFβ1‐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 TGFβ1‐mediated pro‐fibrotic responses. Experimental approach The effects of TGFβ1 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 TGFβ1‐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 TGFβ1. TRPA1 mRNA was also down‐regulated by TGFβ1 in a model of lung fibrogenesis in human lung. TRPA1 over‐expression or activation induced HLMF apoptosis, and activation of TRPA1 channel activation by H 2 O 2 induced necrosis. TRPA1 inhibition following TGFβ1 down‐regulation or pharmacological inhibition, protected HLMFs from both apoptosis and necrosis. Lentiviral vector mediated TRPA1 expression was also found to induce sensitivity to H 2 O 2 induced cell death in a TRPA1‐negative HEK293T cell line. Conclusion and Implications TGFβ1 induces resistance of HLMFs to TRPA1 agonist‐ and H 2 O 2 ‐mediated cell death via down‐regulation of TRPA1 channels. Our data suggest that therapeutic strategies which prevent TGFβ1‐dependent down‐regulation of TRPA1 may reduce myofibroblast survival in IPF and therefore improve clinical outcomes.