Matrix Metalloproteinase 9 (MMP9) Inhibitor Prevents Mustard Induced Microvesication and Promotes Cutaneous Wound Healing

Abstract

Skin exposure to the chemical warfare agent, sulfur mustard (bis‐2‐chloroethylsulfide, SM), is characterized by severe blister formation and a prolonged inflammatory response. The mechanisms of these SM toxic effects are still poorly defined, and effective medical countermeasures against SM‐induced cutaneous injury have yet to be established. Animal models demonstrate disruption of the skin architecture at the dermal‐epidermal junction (DEJ) when exposed to the vesicant, SM; the damage may be further exacerbated by overexpression of MMP9. Studies show MMP9 degrades basement membrane (BM) components and regulates inflammation in tissue injuries; inhibition of MMP9 suppresses inflammation and promotes wound repairs in tumors and various wound models. In the present studies, ([N‐hydroxy‐3‐phenyl‐2‐(4‐phenylbenzenesulfonamido) propanamide], BiPS), a specific MMP9 inhibitor, was evaluated for its ability to prevent microvesication, suppress inflammation, and promote wound healing following SM exposure using the mouse ear vesicant model. Treatment of male CD1 mouse ear skin with SM (0.08 mg) caused a characteristic SM induced injury including edema, inflammatory cell infiltration, and the formation of microvesicles at the DEJ. Expression of MMP9 mRNA and protein in the skin progressively increased with time 24–168 h following SM exposure. Immunofluorescence studies showed disruption of the BM molecule type IV collagen (COL4), increased expression of inflammation marker, COX2, and upregulation of the skin wound marker keratin 6 (K6) in SM induced skin wounds. SM also caused macrophage (F4/80) accumulation in the tissue which persisted up to 168 h post exposure. Pretreatment of ear skin with BiPS significantly reduced SM‐induced dermal edema and maintained the integrity of the DEJ‐BM as evidenced by contiguous expression of COL4. At 168 h post SM exposure, mRNA and protein expression of MMP9 was significantly downregulated in BiPS treated mice. BiPS treatment also reduced the number of macrophages accumulating in the tissue, and suppressed expression of COX2, and downregulated expression of K6. Taken together, these data indicate that BiPS treatment was able to suppress both inflammation and degradation of BM zone in skin due to SM. This compound was effective in targeting MMP9 to protect against SM induced microvesication and promote wound repairs. MMP9 inhibitors may be useful as medical countermeasure against SM‐induced cutaneous injury.Support or Funding InformationSupported by NIH grants ES005022 and AR055073.