Inflammatory cytokine response in sulfur mustard-exposed mouse skin†‡

Abstract

Assessment of anti-inflammatory therapies against sulfur-mustard (bis(2-chloroethyl)sulfide, HD)-induced skin injury has mainly relied on qualitative histopathological evaluation. Development of quantifiable inflammatory biomarkers using fast and reliable molecular methods is needed for screening anti-inflammatory drugs against HD injury. In this study, we used two different HD exposure models to determine the in vivo cutaneous response of the inflammatory cytokines interleukin-6 (IL-6), IL-1alpha, IL-1beta and tumor necrosis factor alpha (TNF-alpha), in order to identify a suitable inflammatory biomarker common to both models. In the first model, the backs of hairless mice were exposed to HD vapor (1.4 g m(-3)) or sham controls for 6 min using an occluded vapor cup technique. In the second model, right ears of CD1 mice were exposed to a solution (5.0 microl of 195 mM) of HD (0.16 mg) in dichloromethane (CH2Cl2) whereas left ears received only CH2Cl2 (vehicle control). Sulfur-mustard-induced skin inflammation was assessed in skin punch specimens collected at time points up to 24 h post-exposure. Edema was determined by measuring tissue weight, and cytokine content was measured by enzyme immunosorbent assay. Characterized by an increase in edema and IL-6, HD provoked a cutaneous inflammatory response in both models beginning at 6 h post-exposure and continuing to 24 h. An increase in IL-1alpha was observed only in the hairless mouse model, also beginning at 6 h post-exposure and continuing to 24 h. No IL-1beta or TNF-alpha response was observed at any time point in either exposure model. These data document the in vivo production of cutaneous IL-6, a distinct inflammatory biomarker, in two different HD exposure models. We conclude that IL-6 should be a useful in vivo biomarker for evaluating anti-inflammatory drugs against HD-induced skin injury.