TGFβ1 induces resistance of human lung myofibroblasts to cell death via downregulation of TRPA1

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 in human lung myofibroblast (HLMF) cell death and TGFβ1-mediated pro-fibrotic responses. Experimental approach We studied HLMFs derived from IPF patients and non-fibrotic patient controls, looking at the effect of TGFβ1 stimulation on TRPA1 expression and cell death sensitivity. We also examined a human lung model of TGFβ1-dependent fibrogenesis. Key results We found that 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 downregulated by TGFβ1 in a human model of lung fibrogenesis. TRPA1 over-expression or activation induced HLMF apoptosis, and TRPA1 activation by H2 O2 induced necrosis. TRPA1 inhibition resulting from TGFβ1 downregulation or pharmacological inhibition protected HLMFs from both apoptosis and necrosis. Lentiviral vector mediated TRPA1 expression was also found to induce sensitivity to H2 O2 induced cell death in a TRPA1-negative HEK293T cell line. Conclusion and implications TGFβ1 induces resistance of HLMFs to TRPA1 agonist- and H2 O2 -mediated cell death via downregulation of TRPA1. Our data suggest that therapeutic strategies which prevent TGFβ1-dependent downregulation of TRPA1 may reduce myofibroblast survival in IPF and therefore improve clinical outcomes.