TRPA1 ion channel expression in human lung myofibroblasts

Abstract

Introduction: Idiopathic pulmonary fibrosis (IPF) is a progressive disease of unknown aetiology. TGFβ1 is a key cytokine driving pro-fibrotic myofibroblast activity. Ca2+ signals are critical in TGFβ1 driven pro-fibrotic functions and the Ca2+ permeable transient receptor potential (TRP)A1 channel is implicated in TGFβ1-driven pro-fibrotic responses. The role of TRPA1 in human lung fibrosis is unknown. Methods: Human lung myofibroblasts (HLMFs) were derived from non-fibrotic (NF) and IPF lung tissue. TRP channel expression and function were examined using RT-PCR, patch clamp electrophysiology and flow cytometry. TRPA1 activity was investigated using the TRPA1 agonists allyl-isothiocyanate (AITC) and JT010 and the selective antagonist A96707A. A human experimental model of lung fibrosis was used to assess the activity of TRPA1 ex vivo. Results: TRPA1 was the most abundant TRP channel in HLMFs out of 22 TRP channels analysed in both NF and IPF donors. TRPA1 agonists elicited functional TRPA1 currents in HLMFs which were inhibited by A96707A. TGFβ1 reduced both TRPA1 protein and mRNA expression in HLMFs, and TRPA1 mRNA expression was downregulated in lung tissue exposed to TGFβ1. Blocking TRPA1 did not inhibit myofibroblast contraction, changes in αSMA stress fibres, or FBS-induced wound healing. Furthermore, TRPA1 blockers did not inhibit TGFβ1-induced fibrotic changes in the experimental model of fibrosis. Conclusion: HLMFs express TRPA1. TRPA1 blockers do not prevent HLMF pro-fibrotic activity or TGFβ-induced experimental fibrosis.