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.