Redox-sensitive TRP ion channels in the interaction between human lung myofibroblasts and oxidative stress

In idiopathic pulmonary fibrosis (IPF), human lung myofibroblasts (HLMFs) are observed in “fibroblastic foci” which are thought to represent abnormal persistence of myofibroblasts, in part because of failure of normal apoptosis. Oxidative stress is observed in many diseases including IPF. To date however, therapeutics directed specifically at “oxidative stress” have had no important clinical benefit for patients. Part of this failure is our lack of a nuanced understanding of the specific redox signalling and homeostasis abnormalities in disease. Some members of the transient receptor potential cation channels (TRP) are sensitive to redox status and may contribute to important cellular activities in response to oxidative stress.

I describe the production and validation of new tools for the study of expression of redox-sensitive TRP cation channels family members, ankyrin 1 (TRPA1) and melastatin 2 (TRPM2). I describe the mRNA, protein, and functional ion current expression of these channels in cells derived from human lungs, including HLMFs. Importantly I highlight problems with the sensitivity and specificity of anti-TRPA1 antibodies widely used in the literature.

Transforming factor β1(TGFβ1) is strongly implicated in driving IPF pathogenesis, and I show that TGFβ1 reduces TRPA1 expression in HLMFs. TRPA1 activation was found to play a role in HLMF cell death induced by H2O2 and other agonists, and TGFβ1 exposure induced resistance to this agonist-dependent HLMF death via the downregulation of TRPA1. This may go towards explaining the persistence of myofibroblasts in IPF and other fibrotic diseases.

Finally, I study for the first time the H₂O₂ elimination dynamics in HLMFs using genetically encoded redox sensors. These novel tools have been adapted to enable the future study of specific interactions between TRP channels and other genes with cellular redox homeostasis.