Contact sensitisers activate keratinocytes and induce cytotoxicity via Transient Receptor Potential Ankyrin 1 in...

Allergic contact dermatitis (ACD) is a frequent inflammatory skin disease with limited therapeutic options. While neuronal Transient Receptor Potential Ankyrin 1 (TRPA1) has been implicated in ACD, the role of keratinocyte TRPA1 remains unclear. We investigated whether allergen binding to keratinocyte TRPA1 drives cytotoxicity, cytokine release and inflammatory amplification.

We combined in vivo oxazolone-induced hypersensitivity in wild-type and Trpa1 knockout mice with pharmacological inhibition by HC-030031, in vitro assays using TRPA1-expressing Chinese hamster ovary (CHO) cells and primary keratinocytes, RNAscope localisation in human and murine skin, cytokine profiling and in silico docking analyses of allergen-TRPA1 interactions.

TRPA1 deletion or antagonism markedly reduced oxazolone-induced ear swelling, vascular responses and histopathology. Strong contact sensitisers (2,4-dinitrochlorobenzene [DNCB], 2,4-dinitrofluorobenzene [DNFB], oxazolone and formaldehyde) activated TRPA1, inducing Ca²⁺ influx, cytotoxicity and IL-1α release, effects absent in Trpa1-deficient cells and inhibited by HC-030031. RNAscope confirmed keratinocyte TRPA1 expression in human and mouse skin. Docking revealed allergen-specific binding modes, where covalent cysteine modification and A-loop stabilisation correlated with potency. Consistent with these observations allergen-induced ROS, which also target the cysteine cluster of TRPA1, may further lower the channel's activation threshold and thereby amplify allergen-driven cytotoxicity.

Keratinocyte TRPA1 integrates direct allergen binding with ROS-mediated sensitisation to drive cytotoxicity and IL-1α release. This dual mechanism helps explain sensitiser potency and positions TRPA1 antagonism as a promising therapeutic approach in ACD, while providing a framework for chemical risk assessment.