Sulfur mustard (SM), a chemical weapon first employed during World War I, targets the skin, eyes, and lung. It remains a significant military and civilian threat. The characteristic response of human skin to SM involves erythema of delayed onset, followed by edema with inflammatory cell infiltration, the appearance of large blisters in the affected area, and a prolonged healing period. Several in vivo and in vitro models have been established to understand the pathology and investigate the mechanism of action of this vesicating agent in the skin. SM is a bifunctional alkylating agent which reacts with many targets including lipids, proteins, and DNA, forming both intra- and intermolecular cross-links. Despite the relatively nonselective chemical reactivity of this agent, basal keratinocytes are more sensitive, and blistering involves detachment of these cells from their basement membrane adherence zones. The sequence and manner in which these cells die and detach is still unresolved. Much has been discovered over the past two decades with respect to the mechanisms of SM-induced cytotoxicity and the intracellular and extracellular targets of this vesicant. In this review, the effects of SM exposure on the skin are described, as well as potential mechanisms mediating its actions. Successful therapy for SM poisoning will depend on following new mechanistic leads to develop drugs that target one or more of its sites of action.

Sulfur mustard (SM, bis(2-chloroethyl)sulfide) is a bifunctional alkylating agent that causes dermal inflammation, edema and blistering. To investigate the pathogenesis of SM-induced injury, we used a vapor cup model which provides an occlusive environment in which SM is in constant contact with the skin. The dorsal skin of SKH-1 hairless mice was exposed to saturated SM vapor or air control. Histopathological changes, inflammatory markers and DNA damage were analyzed 1–14 days later. After 1 day, SM caused epidermal thinning, stratum corneum shedding, basal cell karyolysis, hemorrhage and macrophage and neutrophil accumulation in the dermis. Cleaved caspase-3 and phosphorylated histone 2A.X (phospho-H2A.X), markers of apoptosis and DNA damage, respectively, were increased whereas proliferating cell nuclear antigen (PCNA) was down-regulated after SM exposure. By 3 days, epithelial cell hypertrophy, edema, parakeratosis and loss of epidermal structures were noted. Enzymes generating pro-inflammatory mediators including myeloperoxidase and cyclooxygenase-2 were upregulated. After 7 days, keratin-10, a differentiation marker, was evident in the stratum corneum. This was associated with an underlying eschar, as neoepidermis began to migrate at the wound edges. Trichrome staining revealed increased collagen deposition in the dermis. PCNA expression in the epidermis was correlated with hyperplasia, hyperkeratosis, and parakeratosis. By 14 days, there was epidermal regeneration with extensive hyperplasia, and reduced expression of cleaved caspase-3, cyclooxygenase-2 and phospho-H2A.X. These findings are consistent with the pathophysiology of SM-induced skin injury in humans suggesting that the hairless mouse can be used to investigate the dermatoxicity of vesicants and the potential efficacy of countermeasures.

No abstract

No abstract

Cutaneous exposure to sulfur mustard [bis(2-chloroethyl) sulfide; SM] produces a delayed inflammatory skin response and severe tissue injury. Pig skin has organ similarities to human skin that is characterized by the content and types of epidermal lipids, the density of hair follicles and presence of sweat glands, which together afford penetration of topically applied compounds, complex inflammatory responses, and subsequent wound healing. The goal of this study was to identify in vivo proinflammatory biomarkers of the SM porcine skin injury within 72 h after SM challenge, using the weanling pig model. Changes in gene expression of inflammatory mediators were examined at 3, 6, 24, 48, and 72 h, using subtraction library analyses and by quantitation of selected transcripts by reverse transcription-polymerase chain reaction (RT-PCR). Sequence analysis of subtraction libraries identified up-regulation of IL-8 at 24, 48, and 72 h. No other specific proinflammatory gene transcripts were isolated from the libraries. Specific transcript RT-PCR analysis showed increased production of interleukin-1beta (IL-1beta), interleukin-6 (IL-6), interleukin-8 (IL-8), and matrix metalloproteinase-9 (MMP-9, gelatinase B) mRNA levels in response to SM exposure. Tumor necrosis factor-alpha (TNF-alpha) expression was only slightly increased and no change in the levels of expression was observed for monocyte chemoattractant protein-1 and MMP-2. This study identifies the main proinflammatory mediators involved in SM-induced skin injury in a weanling pig model. The results suggest transcriptional activity in the inflammatory response proteins IL-8, IL-6, IL-1beta, and MMP-9 and modest changes in TNF-alpha that together produce inflammation and contribute to the pathogenesis of SM dermatotoxicity. Therefore, drugs preventing SM-induced inflammation should be prime candidates for medical intervention to lessen collateral inflammation associated with tissue destruction.