The prevention and treatment of cutaneous injury secondary to chemical warfare agents. Application of these finding to other dermatologic conditions and wound healing

Clinical Practice Guidelines for Prevention, Diagnosis and Management of Early and Delayed-onset Ocular Injuries Due to Mustard Gas Exposure

PURPOSE

To develop clinical practice guidelines (CPGs) for prevention, diagnosis, treatment and follow-up of ocular injuries caused by exposure to mustard gas.

METHODS

The clinical questions were designed by the guideline team. Websites and databases including National Guidelines Clearinghouse, National Institute for Clinical Excellence, Cochrane, and PubMed were searched to find related CPGs and explore possible answers to the clinical questions. Since there were no relevant CPGs in the literature, related articles in Persian and English languages were extracted. Each article along with its level of evidence was summarized. Additionally, hand search was performed by looking the reference list of each article. Consequently, recommendations were developed considering the clinical benefits and side effects of each therapeutic modality. The recommendations were re-evaluated in terms of customization criteria. All recommendations along with the related evidence were scored from 1 to 9 by experts from all medical universities of Iran. The level of agreement among the experts was evaluated by analyzing the given scores.

RESULTS

The agreement was achieved for all recommendations. The experts suggested a number of minor modifications which were applied to the recommendations. Finally, CPGs were developed with 98 recommendations under three major domains including prevention of injury, diagnosis and management of the acute and delayed-onset mustard gas ocular injuries.

CONCLUSION

Considering the lack of CPGs for the prevention, diagnosis, and management of mustard gas-induced keratitis, these recommendations would be useful to prevent the serious ocular complications of mustard gas and standardize eye care services to the affected individuals.

A clinicopathological approach to sulfur mustard-induced organ complications: a major review

CONTEXT

Sulfur mustard (SM), with an old manufacturing history still remains as potential threat due to easy production and extensive effects.

OBJECTIVES

Increasing studies on SM indicates the interest of researchers to this subject. Almost all human body organs are at risk for complications of SM. This study offers organ-by-organ information on the effects of SM in animals and humans.

METHODS

The data sources were literature reviews since 1919 as well as our studies during the Iraq-Iran war. The search items were SM and its all other nomenclatures in relation to, in vivo, in vitro, humans, animals, eye, ocular, ophthalmic, lungs, pulmonary, skin, cutaneous, organs and systemic. Amongst more than 1890 SM-related articles, 257 more relevant clinicopathologic papers were selected for this review.

RESULTS

SM induces a vast range of damages in nearly all organs. Acute SM intoxication warrants immediate approach. Among chronic lesions, delayed keratitis and blindness, bronchiolitis obliterans and respiratory distress, skin pruritus, dryness and cancers are the most commonly observed clinical sequelae.

CONCLUSION

Ocular involvements in a number of patients progress toward a severe, rapid onset form of keratitis. Progressive deterioration of respiratory tract leads to "mustard lung". Skin problems continue as chronic frustrating pruritus on old scars with susceptibility to skin cancers. Due to the multiple acute and chronic morbidities created by SM exposure, uses of multiple drugs by several routes of administrations are warranted.

[Cutaneous and systemic toxicology of vesicants used in warfare]

Vesicants are a group of chemicals used in warfare. The most representative agent is yperite, also known as mustard gas. The blisters that appeared on those exposed to yperite during combat in the First World War are responsible for the current name--vesicants--for this group of chemicals. Their affects are produced mainly through localized action of liquid or vapor forms on the skin, eyes, and respiratory tract. However, the high absorption of the liquid form through the skin or the vapor form on inhalation may cause substantial systemic effects. Here we analyze these effects, treatment of intoxication, and long-term sequelae, drawing on our experience and a review of the literature.

Mechanisms mediating the vesicant actions of sulfur mustard after cutaneous exposure

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.

Mustard gas or sulfur mustard: an old chemical agent as a new terrorist threat

Sulfur mustard is a member of the vesicant class of chemical warfare agents that causes blistering to the skin and mucous membranes. There is no specific antidote, and treatment consists of systematically alleviating symptoms. Historically, sulfur mustard was used extensively in inter-governmental conflicts within the trenches of Belgium and France during World War I and during the Iran-Iraq conflict. Longitudinal studies of exposed victims show that sulfur mustard causes long-term effects leading to high morbidity. Given that only a small amount of sulfur mustard is necessary to potentially cause an enormous number of casualties, disaster-planning protocol necessitates the education and training of first-line healthcare responders in the recognition, decontamination, triage, and treatment of sulfur mustard-exposed victims in a large-scale scenario.

Early effects of iodine on DNA synthesis in sulfur mustard-induced skin lesions

Sulfur mustard (SM) is powerful alkylator and highly cytotoxic blisterogen in both humans and animals. This study in male guinea pigs shows that, at an early stage (5 h) after SM exposure, a marked increase occurred in epithelial nuclear vacuolation, epidermal thickening, and dermal acute inflammation. Topical iodine treatment reduced the severity of these parameters. The rate of DNA synthesis expressed by incorporation of bromodeoxyuridine was reduced upon topical treatment with iodine only or SM only by 46 and 72%, respectively. Iodine treatment following SM exposure exerted an effect similar to that of SM only, indicating that DNA synthesis is not directly involved in the mechanism of action of iodine-induced protection.

Mustard: a potential agent of chemical warfare and terrorism

As one of the most important vesicant agents, the destructive properties of mustards on the skin, eyes and respiratory system, combined with a lack of antidote, makes them effective weapons. Such weapons are inexpensive, easily obtainable and frequently stockpiled. Sulphur mustard (mustard gas) has been used as a chemical warfare agent in at least 10 conflicts. In this article, the use of mustard as a potential agent of chemical warfare and terrorism is outlined. The dose-dependent effects of acute sulphur mustard exposure on the skin, eyes, and respiratory system are described, as well as the possible extents of injuries, the mechanisms of action and the long-term complications. Prevention and management of mustard exposure are briefly discussed. The need for awareness and preparedness in the dermatological community regarding mustard exposure is emphasized.

Medical aspects of sulphur mustard poisoning

Sulphur mustard is one of the major chemical warfare agents developed and used during World War I. Large stockpiles are still present in several countries. It is relatively easy to produce and might be used as a terroristic weapon. Sulphur mustard is a vesicant agent and causes cutaneous blisters, respiratory tract damage, eye lesions and bone marrow depression. The clinical picture of poisoning is well known from the thousands of victims during World War I and the Iran-Iraq war. In the latter conflict, sulphur mustard was heavily used and until now about 30,000 victims still suffer from late effects of the agent like chronic obstructive lung disease, lung fibrosis, recurrent corneal ulcer disease, chronic conjunctivitis, abnormal pigmentation of the skin, and several forms of cancer. Despite enormous research efforts during the last 90 years, no specific sulphur mustard antidote has been found. The prospering knowledge and developments of modern medicine created nowadays new chances to minimize sulphur mustard-induced organ damage and late effects.

Medical management of incidents with chemical warfare agents

Successful management of incidents with chemical warfare agents strongly depends on the speed of medical help and the ability of helpers to react properly. Though the general principles of clinical toxicology, such as decontamination, stabilization, patient evaluation and symptomatic treatment are similar for many toxicants, chemical warfare agents deserve special attention because of their very high inhalative and cutaneous toxicity, rapid onset of the disease and multiple organ failures. This article describes the medical management of mass casualties with blister agents, nerve agents and blood agents from the viewpoint of a clinical toxicologist. Characteristic diagnostic signs, decontamination procedures and therapeutic schemes for these agents are described. Treatment options are discussed. The importance of planning (e.g. antidote availability) and preparedness is emphasized.

Characterization of the Initial Response of Engineered Human Skin to Sulfur Mustard

We have used a new approach to identify early events in sulfur mustard-induced, cutaneous injury by exposing human, bioengineered tissues that mimic human skin to this agent to determine the morphologic, apoptotic, inflammatory, ultrastructural, and basement membrane alterations that lead to dermal-epidermal separation. We found distinct prevesication and post-vesication phases of tissue damage that were identified 6 and 24 h after sulfur mustard (SM) exposure, respectively. Prevesication (6 h) injury was restricted to small groups of basal keratinocytes that underwent apoptotic cell death independent of SM dose. Immunoreactivity for basement membrane proteins was preserved and basement membrane ultrastructure was intact 6 h after exposure. Dermal-epidermal separation was seen by the presence of microvesicles 24 h after SM exposure. This change was accompanied by the dose-dependent induction of apoptosis, focal loss of basement membrane immunoreactivity, increase in acute inflammatory cell infiltration, and ultrastructural evidence of altered basement membrane integrity. These studies provide important proof of concept that bioengineered, human skin demonstrates many alterations previously found in animal models of cutaneous SM injury. These findings further our understanding of mechanisms of SM-induced damage and can help development of new countermeasures designed to limit the morbidity and mortality caused by this chemical agent.

Involvement of tumor necrosis factor-alpha in sulfur mustard-induced skin lesion; effect of topical iodine

Sulfur mustard (SM), also termed mustard gas, is a potent vesicant that elicits an inflammatory response upon exposure of the skin. Evaluation of mouse ear 3 h after SM exposure revealed acute inflammatory-cell aggregates in the vascular beds accompanied by strongly TNF-alpha-positive neutrophils. Eight hours after SM exposure, this phenomenon became intensified and associated with infiltration into the adjacent dermis. In ear skin topically treated with iodine, however, no inflammatory cells were observed 3 h after SM exposure; 8 h postexposure, blood vessels contained very few TNF-alpha-positive inflammatory cells. Since TNF-alpha induction was shown to be associated with reactive oxygen species production, we studied the effect of iodine on activated peritoneal mouse neutrophils. Iodine elicited a concentration-dependent reduction in the oxidative burst of activated neutrophils. Iodine also scavenged hydroxyl radicals generated by glucose oxidase in a concentration-dependent manner. The involvement of TNF-alpha in SM-induced skin toxicity was confirmed by reduction of 49 and 30% in ear edema following administration of 1 and 2 mug anti-TNF-alpha antibodies, respectively. These findings were corroborated by quantitative analysis of the histological findings showing 46% reduction in acute inflammation and no signs of subacute inflammation in the treated group, in contrast to the control group treated with SM only. Other epidermal (microblister formation, ulceration, and necrosis) and dermal (neutrophilia, hemorrhage, and necrosis) parameters also showed marked reductions in the antibodies-treated group in comparison to controls. The combination of iodine and antiTNF-alpha antibodies might constitute a new approach for treatment of SM-exposed individuals.

Reduced sulfur mustard-induced skin toxicity in cyclooxygenase-2 knockout and celecoxib-treated mice

Sulfur mustard (SM), a potent vesicant and chemical warfare agent, induces tissue damage involving an inflammatory response, including vasodilatation, polymorphonuclear infiltration, production of inflammatory mediators, and cyclooxygenase activity. To evaluate the role of cyclooxygenase-1 and -2 (COX-1, COX-2) in sulfur mustard-induced skin toxicity, we applied the agent to the ears of wildtype (WT) and COX-1- and COX-2-deficient mice. In the latter, ear swelling 24 and 48 h after exposure was significantly reduced (P < 0.05) by 55% and 30%, respectively, compared to WT. Quantitative histopathology revealed no epidermal ulceration in COX-2-deficient mice but some degree of severity in WT. COX-2-deficient mice showed significant reductions (P < 0.05) in severity of epidermal necrosis (29%), acute inflammation (42%), and hemorrhage (25%), compared to the WT mice. COX-1 deficiency resulted in significant exacerbation (P < 0.05) in severity of some parameters, including increases of 4.6- and 1.2-fold in epidermal ulceration and epidermal necrosis, respectively, compared to WT. Postexposure treatment of normal male ICR mice with the selective COX-2 inhibitor celecoxib resulted in significant reductions of 27% (P < 0.05) and 28% (P < 0.01) in ear swelling at intervals of 40 and 60 min between exposure and treatment, respectively. Histopathological evaluation revealed significant reductions (P < 0.05) in subepidermal microblister formation (73%) and dermal necrosis (32%), compared to the control group. These findings may indicate that COX-2 participates in the early stages of sulfur mustard-induced acute skin toxicity and that COX-1 might exert some protective function against this chemical insult.