A Cutaneous Nitrogen Mustard Murine Injury Model to Study the Pathophysiology of its Long-term Effects

Abstract

<b>Abstract ID 23809</b> <b>Poster Board 19</b> Vesicating agents cause skin injury with blisters upon cutaneous exposure and this can lead to secondary infections as well as systemic toxicity. These acute consequences can further lead to long-term skin effects including long-lasting lesions, necrosis, wounding, hyperpigmentation and scarring of the skin. Sulfur mustard (SM) has been the most widely used chemical weapon and it remains a concern for use in warfare and terrorist activities. We currently lack effective therapies for either the acute or long-term effects of SM. Development of therapies has become an urgent need as SM exposure is thought to be a contributing factor in Gulf War Illness, a syndrome experienced by many War veterans, and remains a potent chemical arsenal. In this study, we aimed to develop a nitrogen mustard (NM, a structural analog of SM) induced long-term skin injury model in C57BL/6 mice, which will enable future studies to explore underlying mechanisms of SM toxicity and to test potential therapies. Male C57BL/6 mice were topically exposed to either 0.5 mg or 1.0 mg NM in 100 mL of acetone. Pictures were taken at various timepoints over a 3-month period and skin lesions were scored. Mice were sacrificed and skin tissue collected at various timepoints after NM-exposure. Skin samples were fixed, sectioned, and stained for histological analyses. NM exposure caused skin lesions including erythema, edema, and necrosis in mice at both the exposure doses. In the 1 mg exposure group, erythema and edema were seen at 24 hours and worsened by day 3 post-exposure, at which point erythema plateaued while edema peaked at 5 days and declined by 7 days after exposure. In the 0.5 mg exposure group, erythema and edema were seen at 24 hours and worsened at day 3, with erythema disappearing by 2 weeks post-exposure and edema decreasing but remaining apparent throughout the study period. Necrosis was first seen at 3 days after exposure in both the groups, peaking at day 5 and then declining at day 7 post-exposure in the 1 mg group, while increasing slightly and remaining apparent throughout the study period of 3 months for the 0.5 mg group. Microvesications and scabs first appeared at 24 hours, worsened at 2 weeks, and mostly disappeared by 3 months post NM-exposure. Hyperkeratosis, epidermal thickness and scabbing were observed in both the exposure groups; however, scabbing and inflammatory response was more severe in 1.0 mg exposure group. Further analyses will be carried to characterize skin injury, such as changes in pigmentation, hair regrowth, wound size, and burns. Overall, these results indicate that 0.5 mg NM can be used for further histologic and mechanistic studies in this mouse model to establish useful biomarkers that can assist to explore potential therapies for long-term mustard effects.