N-Acetyl-L-cysteine inhibits sulfur mustard-induced and TRPA1-dependent calcium influx.

Transient receptor potential family channels (TRPs) have been identified as relevant targets in many pharmacological as well as toxicological studies. TRP channels are ubiquitously expressed in different tissues and act among others as sensors for different external stimuli, such as mechanical stress or noxious impacts. Recent studies suggest that one member of this family, the transient receptor potential ankyrin 1 cation channel (TRPA1), is involved in pain, itch, and various diseases, suggesting TRPA1 as a potential therapeutic target. As a nociceptor, TRPA1 is mainly activated by noxious or electrophilic compounds, including alkylating substances. Previous studies already revealed an impact of 2-chloroethyl-ethyl sulfide on the ion channel TRPA1. In this study, we demonstrate that sulfur mustard (bis-(2-chloroethyl) sulfide, SM) activates the human TRPA1 (hTRPA1) in a dose-dependent manner measured by the increase in intracellular Ca2+ concentration ([Ca2+]i). Besides that, SM-induced toxicity was attenuated by antioxidants. However, very little is known about the underlying mechanisms. Here, we demonstrate that N-acetyl-L-cysteine (NAC) prevents SM-induced hTRPA1-activation. HEK293-A1-E cells, overexpressing hTRPA1, show a distinct increase in [Ca2+]i immediately after SM exposure, whereas this increase is reduced in cells pretreated with NAC in a dose-dependent manner. Interestingly, glutathione, although being highly related to NAC, did not show an effect on hTRPA1 channel activity. Taken together, our results provide evidence that SM-dependent activation of hTRPA1 can be diminished by NAC treatment, suggesting a direct interaction of NAC and the hTRPA1 cation channel. Our previous studies already showed a correlation of hTRPA1-activation with cell damage after exposure to alkylating agents. Therefore, NAC might be a feasible approach mitigating hTRPA1-related dysregulations after exposure to SM.