Use of the mouse ear vesicant model to evaluate the effectiveness of ebselen as a countermeasure to the nitrogen mustard mechlorethamine

Abstract

Previous studies in this and other laboratories have demonstrated that ebselen (EB-1), an organoselenium compound, spares cells from mechlorethamine (HN2) toxicity in vitro. In the present study, the hypothesis that EB-1 will reduce dermal toxicity of HN2 in vivo is put forward and found to have merit. Using the mouse ear vesicant model (MEVM), HN2, applied topically, showed a dose-dependent effect upon ear swelling and thickness 24 h after treatment; whereas tissue injury consistent with vesication was observed at the higher test doses of HN2 (≥ 0.250 µmol per ear). To examine HN2 countermeasure activity using the MEVM, either hydrocortisone (HC), as a positive control, or EB-1, the test countermeasure, was administered as three topical treatments 15 min, 4 and 8 h after HN2 exposure. Using this approach, both HC and EB-1 were found to reduce tissue swelling associated with HN2 toxicity 24 h after exposure to the vesicant. Taken together, these data demonstrate for the first time the effectiveness of EB-1 as a vesicant countermeasure in a relevant in vivo model.

Topical nitrogen mustard exposure causes systemic toxic effects in mice

“…These ions can react with organic and inorganic anions, amino groups, and sulphide groups in biological systems (Wheeler, 1962), causing severe damage even at very low concentrations. To study the cutaneous damage from SM, NM and other analogues, various animal models have been used (Chauhan et al, 1993, Cowan et al, 1993, Dabrowska et al, 1996, Dorandeu et al, 2011, Lomash et al, 2011, Lulla et al, 2013, Papirmeister, Gross, 1985, Riviere et al, 1995, Sharma, Vijayaraghavan, 2008, Wormser, 1991). However, at present, mechanistic aspects of the injury are still poorly understood and the lack of suitable models hampers the development and screening of effective therapeutic and prophylactic compounds.…”

“…NM has crosslinking property similar to SM, is commercially available and due to the containment facility required for SM, has been used by several groups to study vesicant--induced injury (Hardej and Billack, 2007, Lulla, Reznik, 2013, Pino and Billack, 2008, Sharma et al, 2010a). SKH-1 hairless mice, which has been found to be suitable for experiments with SM and SM analogues, was used as the animal model in this study These studies showed that NM exposure (3.2 mg/mouse) in mice led to severe cutaneous injury, and that NM-related clinical, histopathological, and immunohistochemical effects were similar to those observed following SM-exposure in humans and other animal models (Dorandeu, Taysse, 2011, Jain et al, 2011, Jain et al, 2014a, Pal et al, 2009, Tewari-Singh et al, 2011, Tewari-Singh et al, 2014a, Tewari-Singh et al, 2013, Tewari-Singh et al, 2014b, Tewari-Singh et al, 2009).…”

Assessment of the time-dependent dermatotoxicity of mechlorethamine using the mouse ear vesicant model

“…Mechlorethamine (HN2) is a prototype nitrogen mustard (NM) that shares a similar structure and toxicity profile with the chemical warfare agent sulfur mustard (SM) (Korkmaz et al, 2006; Shakarjian et al, 2010). HN2 is widely used as a surrogate to study and mimic the effects of SM under laboratory conditions (Composto et al, 2018; Lulla et al, 2014; Malaviya et al, 2015; Sunil et al, 2011; Tumu et al, 2018).…”

Multi‐inhibitor prodrug constructs for simultaneous delivery of anti‐inflammatory agents to mustard‐induced skin injury

“…Such irritants add to the edema induced by the mustard. Casillas’ MEVM has become the standard in vivo measurement of antimustard therapeutics . We have used the Casillas MEVM to obtain all the measurements of inflammation suppression reported herein …”

“…Casillas' MEVM has become the standard in vivo measurement of antimustard therapeutics. 15,16 We have used the Casillas MEVM to obtain all the measurements of inflammation suppression reported herein. 6,7,27 While Casillas found edema suppression following treatment with known COX inhibitors, established protease inhibitors, TRPV1 inhibitors, and several other categories of inhibitors, no evidence of summative effects was observed.…”