Localization of substance P gene expression for evaluating protective countermeasures against sulfur mustard

Sulfur mustard [bis(2-chloroethyl)sulfide; SM] is a chemical warfare agent that produces edema and blister formation with a severe inflammatory reaction. The mouse ear vesicant model for SM injury has been used to evaluate pharmacological agents for countering SM dermal injury. The vanilloid olvanil reduces SM-induced edema and mRNA expression of cytokines and chemokines, suggesting that blocking the inflammatory effects of neuropeptides, such as substance P (SP), may provide protection against SM-induced dermal injury. This study examined SP expression in mice exposed to SM (0.16 mg) on the inner surface of the right ear, with or without olvanil pretreatment at 1, 10, 30, 60, and 360 min following exposure. In naïve skin, SP mRNA localization was associated with blood vessels and sebaceous glands. In SM-exposed skin, SP mRNA was also detected in perivascular dermal cells. Immunohistochemical localization of SP protein was observed in the ear skin of naïve, SM-, olvanil/SM-, and vehicle-treated mice. Quantification of SP+ perivascular dermal cells revealed that SM exposure led to a significant increase (P < or = 0.05) in SP+ cells over the observed time period. Olvanil pretreatment significantly reduced (P < or = 0.05) the mean number of SP+ cells at 60 and 360 min. This study demonstrates that SP expression could provide an additional endpoint for evaluating the effectiveness of vanilloid drugs on SM-induced skin inflammation.