Sulfur mustard: its continuing threat as a chemical warfare agent, the cutaneous lesions induced, progress in understanding its mechanism of action, its long-term health effects, and new developments for protection and therapy

MG53 Mitigates Nitrogen Mustard-Induced Skin Injury

Sulfur mustard (SM) and nitrogen mustard (NM) are vesicant agents that cause skin injury and blistering through complicated cellular events, involving DNA damage, free radical formation, and lipid peroxidation. The development of therapeutic approaches targeting the multi-cellular process of tissue injury repair can potentially provide effective countermeasures to combat vesicant-induced dermal lesions. MG53 is a vital component of cell membrane repair. Previous studies have demonstrated that topical application of recombinant human MG53 (rhMG53) protein has the potential to promote wound healing. In this study, we further investigate the role of MG53 in NM-induced skin injury. Compared with wild-type mice, mg53^-/- mice are more susceptible to NM-induced dermal injuries, whereas mice with sustained elevation of MG53 in circulation are resistant to dermal exposure of NM. Exposure of keratinocytes and human follicle stem cells to NM causes elevation of oxidative stress and intracellular aggregation of MG53, thus compromising MG53's intrinsic cell membrane repair function. Topical rhMG53 application mitigates NM-induced dermal injury in mice. Histologic examination reveals the therapeutic benefits of rhMG53 are associated with the preservation of epidermal integrity and hair follicle structure in mice with dermal NM exposure. Overall, these findings identify MG53 as a potential therapeutic agent to mitigate vesicant-induced skin injuries.

Therapeutic Benefits of Stem Cells and Exosomes for Sulfur-Mustard-Induced Tissue Damage

Sulfur mustard (SM) is a highly toxic chemical agent that causes severe tissue damage, particularly to the eyes, lungs, and skin. Despite advances in treatment, there is a need for more effective therapies for SM-induced tissue injury. Stem cell and exosome therapies are emerging as promising approaches for tissue repair and regeneration. Stem cells can differentiate into multiple cell types and promote tissue regeneration, while exosomes are small vesicles that can deliver therapeutic cargo to target cells. Several preclinical studies demonstrated the potential of stem cell, exosome, or combination therapy for various tissue injury, showing improvements in tissue repairing, inflammation, and fibrosis. However, there are also challenges associated with these therapies, such as the requirement for standardized methods for exosome isolation and characterization, the long-term safety and efficacy and reduced SM-induced tissue injury of these therapies. Stem cell or exosome therapy was used for SM-induced eye and lung injury. Despite the limited data on the use for SM-induced skin injury, this therapy is a promising area of research and may offer new treatment options in the future. In this review, we focused on optimizing these therapies, evaluating their safety and efficacy, and comparing their efficacy to other emerging therapeutic approaches potentially for SM-induced tissue injury in the eye, lung, and skin.

Ophthalmic Complications and Managements of Sulfur Mustard Exposure: A Narrative Review

Sulfur mustard (SM) is a lethal chemical agent that affects many organs, particularly the eyes, respiratory system and skin. Even asymptomatic patients with documented SM vapor exposure may develop organ disorder many years later. Patients with even minor signs in the acute stage may experience late complications that necessitate surgery. Early decontamination and conservative measures could help the patients and decrease the complications. Despite decades of research, there is still no effective treatment for either acute or long-term SM-induced ocular complications. Even after multiple medications and surgical procedures, the majority of patients continue to have symptoms. For dry eye, punctual occlusion, autologous eye drops, and aggressive lubrication are used; for persistent epithelial defects (PED), tarsorrhaphy, amniotic membrane transplant, and stem cell transplantation are used; for total limbal stem cell deficiency (LSCD), living-related conjunctivolimbal allograft and keratolimbal allograft are used; for corneal vascularization, steroids, non-steroidal anti-inflammatory drugs, and anti-vascular endothelial growth factor prescribed; and for corneal opacities, corneal transplantation is done. Platelet rich plasma and topical drops containing stem cell transplantation for LSCD, photodynamic therapy paired with subconjunctival or topical anti-vascular endothelial growth factors for corneal vascularization, topical curcumin and topical ciclosporin-A for dry eye, and orbital fat-derived stem cells for PED are all alternative treatments that can be suggested. Despite the experimental and clinical research on the complications of SM exposure over the past decades, there is still no effective treatment for eye complications. However, supportive medical and surgical management has been applied with relatively good outcome.

Research models of sulfur mustard- and nitrogen mustard-induced ocular injuries and potential therapeutics

Sulfur mustard (SM) is a notorious, bifunctional alkylating vesicant that was first used in warfare during World War I in 1917 and since then has been deployed in numerous skirmishes with its most recent documented use being during the Middle Eastern conflicts. Apart from its use in combat and terrorist activities, continual threat of accidental exposure from old stockpiles and improperly discarded munitions is ever present, especially to the innocent and unassuming civilian populations. SM can cause devastating injuries, depending on the dosage of SM exposure, route of exposure, as well as the physiological conditions of the individuals exposed. The most common routes of exposure are ocular, dermal, and exposure to the lungs and respiratory tissues through inhalation. Eyes are the most susceptible organ to SM-induced toxicities owing to their high moisture content and rapidly dividing cells. Additionally, ocular injury causes the most expeditious disablement of individuals even upon whole-body exposures. Therefore, it is imperative to understand the mechanisms underlying SM-induced ocular toxicity and design therapeutic interventions to prevent/mitigate ocular injuries. Ocular SM exposure may cause a wide range of symptoms such as inflammation, lacrimation, itching, dryness, photophobia, edema of the cornea/sclera/retina/iris, conjunctivitis, degradation of the corneal layer, fusion of two or more ocular layers, neovascularization, fibrosis, and temporary or permanent structural damage to one or more ocular layers. These symptoms may lead to vision impairments, resulting in partial or complete blindness that may be permanent. The highly toxic and exceedingly notorious nature of SM makes it a highly regulated chemical, requiring very expensive licensing, security, and safety requirements; thus, the more easily accessible analogue, nitrogen mustard (NM) that mimics SM-induced toxicity and injuries is employed in plethora of studies conducted in different animal models and culture systems. This review provides a comprehensive account of the injuries and symptoms that occur upon ocular SM exposures in human patients as well as studies in animal (in vivo, ex vivo) and cell (in vitro) models of SM and NM ocular exposures. Special emphasis has been laid on highlighting the strengths and lacunae in the research as well as the possible unexplored avenues of mechanisms underlying mustard-induced ocular injury that can be explored in future research endeavors. Furthermore, development of therapeutic interventions and targets of interest in the ocular system exposed to SM and NM, based on studies in human patients as well as in vivo, ex vivo, and in vitro models has been discussed in great depth, providing a valuable knowledge database to delineate pathways associated with vesicant-induced toxicity, and strategies/diagnostic tools against SM-induced toxicity.

Proteomics analysis of chronic skin injuries caused by mustard gas

Sulfur mustard (SM) is an alkylating and forming chemical that was widely used by Iraqi forces during the Iran–Iraq wars. One of the target organs of SM is the skin. Understanding the mechanisms involved in the pathogenesis of SM may help better identify complications and find appropriate treatments. The current study collected ten SM-exposed patients with long-term skin complications and ten healthy individuals. Proteomics experiments were performed using the high-efficiency TMT10X method to evaluate the skin protein profile, and statistical bioinformatics methods were used to identify the differentially expressed proteins. One hundred twenty-nine proteins had different expressions between the two groups. Of these 129 proteins, 94 proteins had increased expression in veterans' skins, while the remaining 35 had decreased expression. The hub genes included RPS15, ACTN1, FLNA, HP, SDHC, and RPL29, and three modules were extracted from the PPI network analysis. Skin SM exposure can lead to oxidative stress, inflammation, apoptosis, and cell proliferation.

Detoxification of the Toxic Sulfur Mustard Simulant by a Supramolecular Antidote in Vitro and in Vivo

Although great potential hazards and threats still occur from sulfur mustard, there are no specific medicine or therapy for the intoxication of sulfur mustard. Herein, we have demonstrated a supramolecular approach for the detoxification of the sulfur mustard simulant CEES (4) in vitro and in vivo by carboxylatopillar[5]arene potassium salts (CP[5]AK 1) efficiently based on host-guest interactions. The encapsulation of CEES (4) by the cavity of the pillar[5]arene 2 is driven by C-H···π interactions between CEES (4) and the electron-rich cavity of pillar[5]arene 2, which was investigated by 1H NMR titration, density functional theory studies, and the independent gradient model studies. CEES (4) is degradated to the reactive sulfonium salts quickly in aqueous media, resulting in the alkylation of DNA and proteins. The sulfonium salts can be encapsulated by CP[5]AK 1 efficiently, which accelerates the degradation of the sulfonium salts about 14 times. The cell and animal experiments indicated that the bioactivities of the sulfonium salts are inhibited with the formation of stable host-guest complexes, and CP[5]AK 1 has a good therapeutic effect on the damages caused by CEES (4) at either pre- or post-treatments. Due to the low cytotoxicity and good therapeutic effect, the anionic pillar[5]arenes are expected to be developed as specific antidotes against sulfur mustard (HD).

Advice on assistance and protection provided by the Scientific Advisory Board of the Organisation for the Prohibition of Chemical Weapons: Part 3. On medical care and treatment of injuries from sulfur mustard

Blister agents damage the skin, eyes, mucous membranes and subcutaneous tissues. Other toxic effects may occur after absorption. The response of the Scientific Advisory Board (SAB) of the Organisation for the Prohibition of Chemical Weapons (OPCW) to a request from the OPCW Director-General in 2013 on the status of medical countermeasures and treatments to blister agents is updated through the incorporation of the latest information. The physical and toxicological properties of sulfur mustard and clinical effects and treatments are summarised. The information should assist medics and emergency responders who may be unfamiliar with the toxidrome of sulfur mustard and its treatment.

Progressive Lung Injury, Inflammation, and Fibrosis in Rats Following Inhalation of Sulfur Mustard

Sulfur mustard (SM) inhalation causes debilitating pulmonary injury in humans which progresses to fibrosis. Herein, we developed a rat model of SM toxicity which parallels pathological changes in the respiratory tract observed in humans. SM vapor inhalation caused dose (0.2-0.6 mg/kg)-related damage to the respiratory tract within 3 days of exposure. At 0.4-0.6 mg/kg, ulceration of the proximal bronchioles, edema and inflammation were observed, along with a proteinaceous exudate containing inflammatory cells in alveolar regions. Time course studies revealed that the pathologic response was biphasic. Thus, changes observed at 3 days post-SM were reduced at 7-16 days; this was followed by more robust aberrations at 28 days, including epithelial necrosis and hyperplasia in the distal bronchioles, thickened alveolar walls, enlarged vacuolated macrophages, and interstitial fibrosis. Histopathologic changes were correlated with biphasic increases in bronchoalveolar lavage (BAL) cell and protein content and proliferating cell nuclear antigen expression. Proinflammatory proteins receptor for advanced glycation end product (RAGE), high-mobility group box protein (HMGB)-1, and matrix metalloproteinase (MMP)-9 also increased in a biphasic manner following SM inhalation, along with surfactant protein-D (SP-D). Tumor necrosis factor (TNF)-α and inducible nitric oxide synthase (iNOS), inflammatory proteins implicated in mustard lung toxicity, and the proinflammatory/profibrotic protein, galectin (Gal)-3, were upregulated in alveolar macrophages and in bronchiolar regions at 3 and 28 days post-SM. Inflammatory changes in the lung were associated with oxidative stress, as reflected by increased expression of heme oxygenase (HO)-1. These data demonstrate a similar pathologic response to inhaled SM in rats and humans suggesting that this rodent model can be used for mechanistic studies and for the identification of efficacious therapeutics for mitigating toxicity.

Long-term Respiratory Effects of Mustard Vesicants

Sulfur mustard and related vesicants are cytotoxic alkylating agents that cause severe damage to the respiratory tract. Injury is progressive leading, over time, to asthma, bronchitis, bronchiectasis, airway stenosis, and pulmonary fibrosis. As there are no specific therapeutics available for victims of mustard gas poisoning, current clinical treatments mostly provide only symptomatic relief. In this article, the long-term effects of mustards on the respiratory tract are described in humans and experimental animal models in an effort to define cellular and molecular mechanisms contributing to lung injury and disease pathogenesis. A better understanding of mechanisms underlying pulmonary toxicity induced by mustards may help in identifying potential targets for the development of effective clinical therapeutics aimed at mitigating their adverse effects.

Effect of sulfur mustard on melanogenesis in vitro

The chemical warfare agent sulfur mustard (SM) affects all cells in the epidermis including melanocytes which are responsible for melanin synthesis. After exposure to SM, pigment abnormalities like hypo- and hyperpigmentation can occur. The underlying molecular pathomechanisms of SM exposure on human melanogenesis have not been elucidated so far. In our study, we investigated the effect of SM on human melanocytes and melanogenesis. Normal human epidermal melanocytes (NHEM) were used as in vitro model and they were exposed to different concentrations of SM (4.5 μM-100 μM). Melanin production was analyzed by absorption measurements at 405 nm. In addition, quantitative real-time PCR (qPCR) and Western blot experiments were performed to determine the expression of essential melanogenesis-related proteins including tyrosinase (TYR), tyrosinase-related protein (TRP) 1 and 2 and microphthalmia transcription factor (MITF). Our findings demonstrated that exposure to low SM concentrations increased melanin synthesis accompanied with an increase in protein expression. In contrast, high SM concentrations led to decreased melanin content and a downregulation in expression of all investigated melanogenesis-associated proteins. We concluded that low SM concentrations may cause hyperpigmentation while high SM concentrations decreased melanin content which may explain hypopigmented skin areas in SM exposed patients.

Expression of cytokines and chemokines in mouse skin treated with sulfur mustard

Sulfur mustard (2,2'-dichlorodiethyl sulfide, SM) is a chemical warfare agent that generates an inflammatory response in the skin and causes severe tissue damage and blistering. In earlier studies, we identified cutaneous damage induced by SM in mouse ear skin including edema, erythema, epidermal hyperplasia and microblistering. The present work was focused on determining if SM-induced injury was associated with alterations in mRNA and protein expression of specific cytokines and chemokines in the ear skin. We found that SM caused an accumulation of macrophages and neutrophils in the tissue within one day which persisted for at least 7 days. This was associated with a 2-15 fold increase in expression of the proinflammatory cytokines interleukin-1β, interleukin-6, and tumor necrosis factor α at time points up to 7 days post-SM exposure. Marked increases (20-1000 fold) in expression of chemokines associated with recruitment and activation of macrophages were also noted in the tissue including growth-regulated oncogene α (GROα/CXCL1), monocyte chemoattractant protein 1 (MCP-1/CCL2), granulocyte-colony stimulating factor (GCSF/CSF3), macrophage inflammatory protein 1α (MIP1α/CCL3), and IFN-γ-inducible protein 10 (IP10/CXCL10). The pattern of cytokines/chemokine expression was coordinate with expression of macrophage elastase/MMP12 and neutrophil collagenase/MMP8 suggesting that macrophages and neutrophils were, at least in part, a source of cytokines and chemokines. These data support the idea that inflammatory cell-derived mediators contribute to the pathogenesis of SM induced skin damage. Modulating the infiltration of inflammatory cells and reducing the expression of inflammatory mediators in the skin may be an important strategy for mitigating SM-induced cutaneous injury.

Combat zone exposure and respiratory tract disease

BACKGROUND

The impact of deployment to combat zones on the respiratory and sinonasal health of U.S. soldiers is an emerging public health concern. Retrospective studies have shown a correlation between deployment and development of post-deployment pathology, particularly of the aerodigestive system. Respiratory disease, including sinusitis, allergic rhinitis, and asthma, are commonly reported in soldiers deployed to the Middle East and Southwest Asia.

METHODS

Current literature pertaining to combat zone exposure and development of respiratory disease was retrieved using PubMed, Embase, Web of Science, and Google Scholar.

RESULTS

Several types of combat zone exposures exist that may play an influential role in the development of upper and lower respiratory tract diseases. Exposures including foreign dusts, harsh environments, particulate size, and close living quarters may play a causative role. The effect of combat zone exposures has been better examined for lower respiratory tract diseases; however, with the theory of the unified airway, the upper respiratory tract may also be involved. There is evidence that the upper respiratory tract is susceptible, with an increased risk for development of sinusitis and sinonasal disease; however, the quality of evidence of the present literature is generally low.

CONCLUSION

More research is necessary to determine a pathophysiologic mechanism between combat zone exposure and the development of sinonasal disease. Practicing otolaryngologists should be aware of the possibility of combat zone exposures that could contribute to rhinologic symptomatology.

Biological effects of adipocytes in sulfur mustard induced toxicity

Sulphur mustard (2,2'-dichloroethyl sulfide; SM) is a vesicant chemical warfare agent whose mechanism of acute or chronic action is not known with any certainty and to date there is no effective antidote. SM accumulation in adipose tissue (AT) has been originally verified in our previous study. To evaluate the biological effect caused by the presence of abundant SM in adipocyte and assess the biological role of AT in SM poisoning, in vitro and in vivo experiments were performed. High content analysis revealed multi-cytotoxicity in SM exposed cells in a time and dose dependent manner, and adipocytes showed a relative moderate damage compared with non-adipocytes. Cell co-culture model was established and revealed the adverse effect of SM-exposed adipocyte supernatant on the growth of co-cultured cells. The pathological changes in AT from 10mg/kg SM percutaneously exposed rats were checked and inflammation phenomena were observed. The mRNA and protein levels of inflammation-related adipokines secreted from AT in rats exposed to 1, 3 and 10mg/kg doses of SM were determined by reverse transcriptase-polymerase chain reaction and enzyme-linked immunosorbent assays. The expressions of proinflammatory and anti-inflammatory adipokines together promoted the inflammation development in the body. The positive correlations between AT and serum adipokine levels were explored, which demonstrated a substantial role of AT in systemic inflammation responding to SM exposure. Thus, AT is not only a target of SM but also a modulator in the SM toxicity.

Mycosis fungoides two decades after exposure to sulphur mustard: a follow-up of 1100 victims

BACKGROUND

Sulphur mustard (SM) is an alkylating chemical warfare agent which causes acute and chronic injuries to the eyes, skin, lung and respiratory tract.

OBJECTIVE

We aimed to investigate the relationship between SM poisoning and Mycosis fungoides (MF) as a late consequence.

MATERIAL AND METHODS

In this retrospective study, the medical files of 1100 Iranian veterans confirmed to have exposure to SM agent during the Iraq-Iran war of the 1980s were reviewed.

RESULTS

All 10 cases with MF were confirmed by clinical and histopathological examinations. The mean age of the studied subjects was 43.3 ± 9.8 (years). In comparison to MF incidence rate in Iranian general population (0.39/100 000 person-years), we found an incidence rate of 0.799/100 000 person-years for MF among those who had short-term exposure to SM. The most common sites for SM lesions were flexural and thin skin areas. The main limitation was the retrospective design.

CONCLUSION

This study indicates that the risk of MF in those exposed to SM may increase over time. Therefore, their follow-up is recommended.

Histopathologic Features Seen with Radiation Recall or Enhancement Eruptions

Background:

Although a radiation recall or enhancement eruption has been associated with a number of chemotherapeutic drugs, the histologic features have rarely been described.

Objective:

Our goal was to define the histologic features of radiation recall and enhancement eruptions in order to better understand their pathogenesis.

Methods:

We present ten patients on chemotherapeutic agents who developed erythematous maculopapular to psoriasiform eruptions often with associated follicular pustules. These eruptions occurred at the sites of prior or concurrent radiation therapy.

Results:

The most common class of drugs inducing these reactions were antibiotic chemotherapeutic agents alone or in combination with other chemotherapeutic drugs. In addition to routine histology, in four patients immunohistochemical staining for p53 was performed at the sites of the eruptions after resolution and at noninvolved sites matched for ultraviolet radiation (UVR) exposure. Histologic features in patients receiving concurrent radiation therapy included epidermal dysplasia, keratinocytes showing features of necrosis, increased mitotic figures, and a mixed inflammatory infiltrate. At sites of prior radiation therapy, the biopsy specimens showed a similar spectrum of epidermal changes and, in some cases, psoriasiform dermatitis with clearing within cells in the upper layers of the epidermis. Additional dermal changes included dermal fibrosis, vasodilatation, and atypical fibroblasts. Moderate to marked solar elastosis was seen in the majority of biopsy specimens. Immunohistochemical studies after resolution showed only a modest increase in p53 staining in epidermal keratinocytes in 3 of 4 sites of recall and enhancement eruptions after resolution of the reactions compared to skin that was matched for similar UVR exposure.

Conclusion:

Cumulative direct DNA damage and oxidative stress are probably important in radiation recall and enhancement eruptions, and these changes may be modulated by underlying nutritional deficits. Cumulative p53 mutations may play some role but are probably not a major factor in these eruptions. Mitochondrial dysfunction, which is known to occur with prior and concurrent radiation and chemotherapy, may be important in these eruptions. In addition to improvements in general nutrition, topical or oral antioxidant therapy may be a potential therapy to avoid radiation enhancement and recall reactions.

Evaluation of miR-9 and miR-143 expression in urine specimens of sulfur mustard exposed patients

Sulfur mustard (SM) or mustard gas is a chemical alkylating agent that causes blisters in the skin (blister gas), burns the eyes and causes lung injury. Some major cellular pathways are involved in the damage caused by mustard gas such as NF-κb signaling, TGF-β signaling, WNT pathway, inflammation, DNA repair and apoptosis. MicroRNAs are non-coding small RNAs (19–25 nucleotides) that are involved in the regulation of gene expression and are found in two forms, extracellular and intracellular. Changes in the levels of extracellular microRNAs are directly associated with many diseases, it is thus common to study the level of extracellular microRNAs as a biomarker to determine the pathophysiologic status. In this study, 32 mustard gas injured patients and 32healthy subjects participated. Comparative evaluation of miR-9 and miR-143 expression in urine samples was performed by Real Time PCR and Graph Pad software. The Mann Whitney t-test analysis of data showed that the expression level of miR-143 and miR-9 had a significant decrease in sulfur mustard individuals with the respective p-value of 0.0480 and 0.0272 compared to normal samples, with an imbalance of several above mentioned pathways. It seems that reducing the expression level of these genes has a very important role in the pathogenicity of mustard gas injured patients.

Using the skin protective lotion IB1 as a substitute for chemical protective gloves

We aimed to evaluate the performance of medical personnel in using the IB1 topical protective lotion on their hands and wrists together with standard disposable medical gloves, compared to standard-issued medical chemical protective gloves. This randomized cross-over study included 144 medical personnel. Primary endpoints were time-to-completion of autoinjection; success rate, number of attempts, and time-to-achieve successful endotracheal intubation; time-to-achieve satisfactory tube fixation; time-to-draw and inject the content of an ampoule; and the total time-to-perform all medical procedures. Secondary endpoints included the subjective assessment of convenience to perform these four procedures with each protective measure. Mean time was significantly shorter using IB1 compared to chemical protective gloves for tube fixation, ampoule drawing, and the total time-to-perform all procedures (58.6±22.7 seconds vs. 71.7±29.7; 31.5±21.8 vs. 38.2±19.4; 137.4±56.1 vs. 162.5±63.6, respectively; P<.001 for all). For all medical procedures, the use of IB1 was reported as significantly more convenient than the use of chemical protective gloves (P<.001 for all comparisons). IB1 with standard medical gloves significantly shorten the time-to-perform medical procedures requiring fine motor dexterities and is subjectively more convenient than chemical protective gloves. IB1 should be considered as an appropriate alternative for medical teams in a chemical event.

Tissue injury and repair following cutaneous exposure of mice to sulfur mustard

In mouse skin, sulfur mustard (SM) is a potent vesicant, damaging both the epidermis and the dermis. The extent of wounding is dependent on the dose of SM and the duration of exposure. Initial responses include erythema, pruritus, edema, and xerosis; this is followed by an accumulation of inflammatory leukocytes in the tissue, activation of mast cells, and the release of mediators, including proinflammatory cytokines and bioactive lipids. These proinflammatory mediators contribute to damaging the epidermis, hair follicles, and sebaceous glands and to disruption of the epidermal basement membrane. This can lead to separation of the epidermis from the dermis, resulting in a blister, which ruptures, leading to the formation of an eschar. The eschar stimulates the formation of a neoepidermis and wound repair and may result in persistent epidermal hyperplasia. Epidermal damage and repair is associated with upregulation of enzymes generating proinflammatory and pro-growth/pro-wound healing mediators, including cyclooxygenase-2, which generates prostanoids, inducible nitric oxide synthase, which generates nitric oxide, fibroblast growth factor receptor 2, and galectin-3. Characterization of the mediators regulating structural changes in the skin during SM-induced tissue damage and wound healing will aid in the development of therapeutic modalities to mitigate toxicity and stimulate tissue repair processes.

Ebselen protects brain, skin, lung and blood cells from mechlorethamine toxicity

Nitrogen mustards are vesicants capable of burning the skin, eyes and respiratory tract of exposed individuals. While generally less toxic than sulfur mustards, these compounds have the potential for use as chemical warfare agents. Presently, no antidote exists for treatment against nitrogen mustard toxicity. The purpose of this study was to investigate the in vitro toxicity of the nitrogen mustard mechlorethamine (HN2) in four cell models: CEM-SS human T cells, A431 human skin epithelial cells, rat hippocampal astrocytes and rat pleural mesothelial cells. Furthermore, the efficacy of the synthetic seleno-organic compound ebselen (Eb) (2-phenyl-1,2- benzisoselenazol-3(2H)-one) as a cytoprotective agent against such toxicity was evaluated. Significant increases in cell viability, as assessed using an MTT assay for viability, was demonstrated when 30μM Eb was used as a cotreatment with HN2 in all cell models tested at the following doses of HN2: A431 skin cells,10—40μM; rat astrocytes, 20 and 40μM; rat mesothelia, 10—40 μM; and human T cells 4—16 μM. Decreases in cell viability and toxicity to HN2 were confirmed using light and scanning electron microscopy. Membrane damage, observed with HN2 exposure, such as blebbing and loss of cell projections, was ameliorated with Eb cotreatment. Our results demonstrate a generalized protective effect observed with Eb cotreatment that suggests that this agent may have potential as an antidote for HN2 exposure and toxicity.

Mustard vesicating agent-induced toxicity in the skin tissue and silibinin as a potential countermeasure

Exposure to the vesicating agents sulfur mustard (SM) and nitrogen mustard (NM) causes severe skin injury with delayed blistering. Depending upon the dose and time of their exposure, edema and erythema develop into blisters, ulceration, necrosis, desquamation, and pigmentation changes, which persist weeks and even years after exposure. Research advances have generated data that have started to explain the probable mechanism of action of vesicant-induced skin toxicity; however, despite these advances, effective and targeted therapies are still deficient. This review highlights studies on two SM analogs, 2-chloroethyl ethyl sulfide (CEES) and NM, and CEES- and NM-induced skin injury mouse models that have substantially added to the knowledge on the complex pathways involved in mustard vesicating agent-induced skin injury. Furthermore, employing these mouse models, studies under the National Institutes of Health Countermeasures Against Chemical Threats program have identified the flavanone silibinin as a novel therapeutic intervention with the potential to be developed as an effective countermeasure against skin injury following exposure to mustard vesicating agents.

Emerging targets for treating sulfur mustard-induced injuries

Sulfur mustard (SM; bis-(2-chlororethyl) sulfide) is a highly reactive, potent warfare agent that has recently reemerged as a major threat to military and civilians. Exposure to SM is often fatal, primarily due to pulmonary injuries and complications caused by its inhalation. Profound inflammation, hypercoagulation, and oxidative stress are the hallmarks that define SM-induced pulmonary toxicities. Despite advances, effective therapies are still limited. This current review focuses on inflammatory and coagulation pathways that influence the airway pathophysiology of SM poisoning and highlights the complexity of developing an effective therapeutic target.

Effects of poly (ADP-ribose) polymerase-1 (PARP-1) inhibition on sulfur mustard-induced cutaneous injuries in vitro and in vivo

Early studies with first-generation poly (ADP-ribose) polymerase (PARP) inhibitors have already indicated some therapeutic potential for sulfur mustard (SM) injuries. The available novel and more potential PARP inhibitors, which are undergoing clinical trials as drugs for cancer treatment, bring it back to the centre of interest. However, the role of PARP-1 in SM-induced injury is not fully understood. In this study, we selected a high potent specific PARP inhibitor ABT-888 as an example to investigate the effect of PARP inhibitor in SM injury. The results showed that in both the mouse ear vesicant model (MEVM) and HaCaT cell model, PARP inhibitor ABT-888 can reduce cell damage induced by severe SM injury. ABT-888 significantly reduced SM induced edema and epidermal necrosis in MEVM. In the HaCaT cell model, ABT-888 can reduce SM-induced NAD(+)/ATP depletion and apoptosis/necrosis. Then, we studied the mechanism of PARP-1 in SM injury by knockdown of PARP-1 in HaCaT cells. Knockdown of PARP-1 protected cell viability and downregulated the apoptosis checkpoints, including p-JNK, p-p53, Caspase 9, Caspase 8, c-PARP and Caspase 3 following SM-induced injury. Furthermore, the activation of AKT can inhibit autophagy via the regulation of mTOR. Our results showed that SM exposure could significantly inhibit the activation of Akt/mTOR pathway. Knockdown of PARP-1 reversed the SM-induced suppression of the Akt/mTOR pathway. In summary, the results of our study indicated that the protective effects of downregulation of PARP-1 in SM injury may be due to the regulation of apoptosis, necrosis, energy crisis and autophagy. However, it should be noticed that PARP inhibitor ABT-888 further enhanced the phosphorylation of H2AX (S139) after SM exposure, which indicated that we should be very careful in the application of PARP inhibitors in SM injury treatment because of the enhancement of DNA damage.

Dynamic cytotoxic profiles of sulfur mustard in human dermal cells determined by multiparametric high-content analysis

Sulfur mustard (SM) is a well known chemical warfare agent that poses a major threat to military personnel and also populace. It targets multiple macromolecules, and its toxic effects are mediated by complex mechanisms. However, the sequence and manner of SM-induced cellular and molecular events underpinning the pathological processes are not fully elucidated. Effective therapeutic agents against SM poisoning are also lacking. The present study aimed to determine the dynamic cytotoxic profiles of SM in primary cultured human epidermal keratinocytes-fetal (HEK-f) and human dermal fibroblasts-adult (HDF-a) by establishing a high content analysis (HCA)-based multiparametric toxicity assay panel. SM was found to produce multiple, concentration-dependent cellular responses, including abnormal cellular morphology, cycle arrest, apoptosis, necrosis, mitochondrial membrane potential imbalance, increased membrane permeability, oxidative stress, DNA damage, and lysosome impairment. Time-course analysis indicated that the cellular and molecular responses related to the highly reactive targets of SM, such as glutathione depletion, reactive oxygen species release, DNA and lysosomal damage, and actin microfilament architecture modification, were congenerous initial events for SM injury. Moreover, this study demonstrated a novel finding that SM induced autophagy, and it was closely related to lysosome alterations in both cell types. Higher susceptibility of HEK-f cells to SM was associated with early lysosomal damage and decreased autophagy activity. Multiparametric HCA also revealed the concentration-dependent cytoprotective effect of hydroxychloroquine in HDF-a cells. The above results provided overall and objective evidence for elucidating the cytotoxic mechanism of SM, and also a good scientific base for further research on countermeasures against SM injury.

Major Contributions towards Finding a Cure for Cancer through Chemotherapy: A Historical Review

The history of cancer chemotherapy is as old as cancer itself. With the increase in the complexities of cancer and the development of resistance towards existing anticancer agents, increased attention is now being paid to the advancement of chemotherapy. Some chemotherapeutic agents were discovered by accident or trial-and-error methods while others were found to be useful for neoplasia when they were being evaluated for some other purpose. Broadly, these agents have been classified as alkylating agents, antimetabolites, platinum compounds, antitumor antibiotics and natural products. Hormones and compounds interfering with hormone metabolism are widely used in cancer treatment, besides monoclonal antibodies and small molecules targeting angiogenesis. In this review an attempt is made to discuss the major breakthroughs that have shaped the course of cancer chemotherapy, helping to decrease the mortality as well as lessen the suffering of patients.

A guanine-ethylthioethyl-glutathione adduct as a major DNA lesion in the skin and in organs of mice exposed to sulfur mustard

Sulfur mustard (SM) is an old chemical warfare but it remains a threat to both militaries and civilians. SM mainly targets skin, eyes and lungs and diffuses to internal organs. At the molecular level, SM is able to damage DNA through the formation of monoadducts and biadduct. Glutathione (GSH) is another critical target of SM in cells since it is part of the detoxification mechanism against alkylating agents. In the present work, we investigated whether SM could form covalent bonds simultaneously with a DNA base and the sulfhydryl group of GSH. The expected guanine adduct, S-[2-(N7-guanyl)-ethylthioethyl]-glutathione (N7Gua-ETE-GSH), was synthesized and detected in several tissues of SKH-1 mice exposed to 60mg/kg of SM in the dorsal-lumbar region. N7Gua-ETE-GSH was detected in all organs studied, except in the liver. The tissue exhibiting the highest levels of N7Gua-ETE-GSH was skin, followed by brain, lungs, kidneys and spleen. N7Gua-ETE-GSH was detected in skin, brain and lungs as long as two weeks after exposure. The persistence was less in other organs. The observation of the formation of N7Gua-ETE-GSH in vivo confirms the variety of damages induced by SM in DNA. It also provides another example of the formation of DNA adducts involving glutathione following in vivo exposure to bifunctional alkylating compounds.

Therapeutic potential of a non-steroidal bifunctional anti-inflammatory and anti-cholinergic agent against skin injury induced by sulfur mustard

Sulfur mustard (bis(2-chloroethyl) sulfide, SM) is a highly reactive bifunctional alkylating agent inducing edema, inflammation, and the formation of fluid-filled blisters in the skin. Medical countermeasures against SM-induced cutaneous injury have yet to be established. In the present studies, we tested a novel, bifunctional anti-inflammatory prodrug (NDH 4338) designed to target cyclooxygenase 2 (COX2), an enzyme that generates inflammatory eicosanoids, and acetylcholinesterase, an enzyme mediating activation of cholinergic inflammatory pathways in a model of SM-induced skin injury. Adult SKH-1 hairless male mice were exposed to SM using a dorsal skin vapor cup model. NDH 4338 was applied topically to the skin 24, 48, and 72 h post-SM exposure. After 96 h, SM was found to induce skin injury characterized by edema, epidermal hyperplasia, loss of the differentiation marker, keratin 10 (K10), upregulation of the skin wound marker keratin 6 (K6), disruption of the basement membrane anchoring protein laminin 322, and increased expression of epidermal COX2. NDH 4338 post-treatment reduced SM-induced dermal edema and enhanced skin re-epithelialization. This was associated with a reduction in COX2 expression, increased K10 expression in the suprabasal epidermis, and reduced expression of K6. NDH 4338 also restored basement membrane integrity, as evidenced by continuous expression of laminin 332 at the dermal-epidermal junction. Taken together, these data indicate that a bifunctional anti-inflammatory prodrug stimulates repair of SM induced skin injury and may be useful as a medical countermeasure.

DNA damage in internal organs after cutaneous exposure to sulphur mustard

Sulphur mustard (SM) is a chemical warfare agent that attacks mainly skin, eye and lungs. Due to its lipophilic properties, SM is also able to diffuse through the skin and reach internal organs. DNA represents one of the most critical molecular targets of this powerful alkylating agent which modifies DNA structure by forming monoadducts and biadducts. These DNA lesions are involved in the acute toxicity of SM as well as its long-term carcinogenicity. In the present work we studied the formation and persistence of guanine and adenine monoadducts and guanine biadducts in the DNA of brain, lungs, kidneys, spleen, and liver of SKH-1 mice cutaneously exposed to 2, 6 and 60mg/kg of SM. SM-DNA adducts were detected in all studied organs, except in liver at the two lowest doses. Brain and lungs were the organs with the highest level of SM-DNA adducts, followed by kidney, spleen and liver. Monitoring the level of adducts for three weeks after cutaneous exposure showed that the lifetime of adducts were not the same in all organs, lungs being the organ with the longest persistence. Diffusion from skin to internal organs was much more efficient at the highest compared to the lowest dose investigated as the result of the loss of the skin barrier function. These data provide novel information on the distribution of SM in tissues following cutaneous exposures and indicate that brain is an important target.

Health-related quality of life of chemical warfare victims: an assessment with the use of a specific tool

Background:

Exposure to chemical warfare gases significantly changes the quality of life (QoL) of victims and has significant chronic adverse effects.

Objective:

This study sought to assess the health-related QoL (HRQoL) of chemical victims by means of a tool specifically designed for this purpose. The correlation of their QoL with several demographic factors was evaluated as well.

Patients and Methods:

In this descriptive cross-sectional study, 120 chemical warfare victims were selected from subjects presenting to selected medical centers in Tehran in 2012 using convenience sampling. Two questionnaires of demographic information and HRQoL of chemical warfare victims (specific tool) were used for data collection. The data were analyzed using SPSS version 20 software (IBM, Armonk, NY, USA).

Results:

The mean and standard deviation (mean ± SD) of scores obtained by chemical warfare victims in physical, psychosocial and spiritual domains was 39.6 ± 16.5, 42.1 ± 15.2 and 82.4 ± 15.4, respectively. Different age groups showed a significant difference in the psychosocial domain score (P < 0.01). Also, the physical and spiritual domain scores had significant differences with respect to the level of education (P < 0.001). The occupational status showed significant differences in the psychosocial and spiritual domains scores of QoL (P < 0.001). The physical and psychosocial domain scores also accounted for a significant difference with respect to the duration and severity of pulmonary symptoms (P < 0.05).

Conclusions:

Considering the importance and high value of spirituality in chemical warfare victims, it can be used as strategically for these patients to help them cope with their injury and improve their physical and psychosocial health and QoL.

Histopathological and immunohistochemical evaluation of nitrogen mustard-induced cutaneous effects in SKH-1 hairless and C57BL/6 mice

Sulfur mustard (SM) is a vesicant warfare agent which causes severe skin injuries. Currently, we lack effective antidotes against SM-induced skin injuries, in part due to lack of appropriate animal model(s) that can be used for efficacy studies in laboratory settings to identify effective therapies. Therefore, to develop a relevant mouse skin injury model, we examined the effects of nitrogen mustard (NM), a primary vesicant and a bifunctional alkylating agent that induces toxic effects comparable to SM. Specifically, we conducted histopathological and immunohistochemical evaluation of several applicable cutaneous pathological lesions following skin NM (3.2mg) exposure for 12-120h in SKH-1 and C57BL/6 mice. NM caused a significant increase in epidermal thickness, incidence of microvesication, cell proliferation, apoptotic cell death, inflammatory cells (neutrophils, macrophages and mast cells) and myleoperoxidase activity in the skin of both mouse strains. However, there was a more prominent NM-induced increase in epidermal thickness, and macrophages and mast cell infiltration, in SKH-1 mice relative to what was seen in C57BL/6 mice. NM also caused collagen degradation and edema at early time points (12-24h); however, at later time points (72 and 120h), dense collagen staining was observed, indicating either water loss or start of integument repair in both the mouse strains. This study provides quantitative measurement of NM-induced histopathological and immunohistochemical cutaneous lesions in both hairless and haired mouse strains that could serve as useful tools for screening and identification of effective therapies for treatment of skin injuries due to NM and SM.

Temporal and spatial features of the formation of DNA adducts in sulfur mustard-exposed skin

Sulfur mustard (SM) is a chemical warfare agent that targets skin where it induces large blisters. DNA alkylation is a critical step to explain SM-induced cutaneous symptoms. We determined the kinetics of formation of main SM-DNA adducts and compare it with the development of the SM-induced pathogenesis in skin. SKH-1 mice were exposed to 2, 6 and 60 mg/kg of SM and treated skin was biopsied between 6h and 21 days. Formation of SM DNA adducts was dose-dependent with a maximum immediately after exposure. However, adducts were persistent and still detectable 21 days post-exposure. The time-dependent formation of DNA adducts was also found to be correlated with the appearance of apoptotic cells. This temporal correlation suggests that these two early events are responsible for the severity of the damage to the skin. Besides, SM-DNA adducts were also detected in areas located next to contaminated zone, thus suggesting that SM diffuses in skin. Altogether, this work provides for the first time a clear picture of SM-induced genotoxicity using DNA adducts as a marker.

Historical perspective on effects and treatment of sulfur mustard injuries

Sulfur mustard (2,2'-dichlorodiethyl sulfide; SM) is a potent vesicating chemical warfare agent that poses a continuing threat to both military and civilian populations. Significant SM injuries can take several months to heal, necessitate lengthy hospitalizations, and result in long-term complications affecting the skin, eyes, and lungs. This report summarizes initial and ongoing (chronic) clinical findings from SM casualties from the Iran-Iraq War (1980-1988), with an emphasis on cutaneous injury. In addition, we describe the cutaneous manifestations and treatment of several men recently and accidentally exposed to SM in the United States. Common, chronic cutaneous problems being reported in the Iranian casualties include pruritis (the primary complaint), burning, pain, redness, desquamation, hyperpigmentation, hypopigmentation, erythematous papular rash, xerosis, multiple cherry angiomas, atrophy, dermal scarring, hypertrophy, and sensitivity to mechanical injury with recurrent blistering and ulceration. Chronic ocular problems include keratitis, photophobia, persistent tearing, sensation of foreign body, corneal thinning and ulceration, vasculitis of the cornea and conjunctiva, and limbal stem cell deficiency. Chronic pulmonary problems include decreases in lung function, bronchitis with hyper-reactive airways, bronchiolitis, bronchiectasis, stenosis of the trachea and other large airways, emphysema, pulmonary fibrosis, decreased total lung capacity, and increased incidences of lung cancer, pulmonary infections, and tuberculosis. There are currently no standardized or optimized methods of casualty management; current treatment strategy consists of symptomatic management and is designed to relieve symptoms, prevent infections, and promote healing. New strategies are needed to provide for optimal and rapid healing, with the goals of (a) returning damaged tissue to optimal appearance and normal function in the shortest period of time, and (b) ameliorating chronic effects. Further experimental research and clinical trials will be needed to prevent or mitigate the acute clinical effects of SM exposure and to reduce or eliminate the long-term manifestations.

Long-term effects of sulfur mustard on civilians' mental health 20 years after exposure (The Sardasht-Iran Cohort Study)

Background

Sulfur mustard (SM) is an alkylating agent that induces short and long term toxicity on various organs. The aim of this study was to assess the long-term psychological symptoms among samples of exposed to sulfur mustard gas compared with unexposed civilians 20 years after exposure.

Methods

This historical cohort study was conducted on 495 civilians of Sardasht and Rabat in two age matched groups, including 367 sulfur mustard exposed participants from Sardasht and 128 unexposed subjects from Rabat. Psychological symptoms was assessed using the Symptom Check List-90 Revised (SCL-90-R) including measures of somatization, obsessive-compulsive, interpersonal sensitivity, depression, anxiety, hostility, phobic anxiety, paranoid ideation, and psychoticism providing three global distress indices namely: Global Severity Index (GSI), Positive Symptom Total (PST) and Positive Symptom Distress Index (PSDI). Comparison was made between exposed and unexposed civilians.

Results

There were significant differences in somatization (P = 0.002), obsessive-compulsive (P = 0.031), depression (P = 0.007), anxiety (P = 0.042), and hostility (P = 0.002), between the exposed and unexposed groups. In addition there were significant differences between two groups concerning the GSI (P = 0.045) and the PSDI (P < 0.001). The differences between two groups in other subscales were not significant.

Conclusions

The findings from this study showed that civilians who exposed to sulfur mustard gas were suffering from a number of psychological symptoms even 20 years after exposure. Providing mental health services and more resource allocation for this community are highly recommended.

Sulfur mustard induces an endoplasmic reticulum stress response in the mouse ear vesicant model

The endoplasmic reticulum (ER) stress response is a cell survival pathway upregulated when cells are under severe stress. Severely damaged mouse ear skin exposed to the vesicant, sulfur mustard (bis-2-chloroethyl sulfide, SM), resulted in increased expression of ER chaperone proteins that accompany misfolded and incorrectly made proteins targeted for degradation. Time course studies with SM using the mouse ear vesicant model (MEVM) showed progressive histopathologic changes including edema, separation of the epidermis from the dermis, persistent inflammation, upregulation of laminin γ2 (one of the chains of laminin-332, a heterotrimeric skin glycoprotein required for wound repair), and delayed wound healing from 24h to 168h post exposure. This was associated with time related increased expression of the cell survival ER stress marker, GRP78/BiP, and the ER stress apoptosis marker, GADD153/CHOP, suggesting simultaneous activation of both cell survival and non-mitochondrial apoptosis pathways. Dual immunofluorescence labeling of a keratinocyte migration promoting protein, laminin γ2 and GRP78/BIP, showed colocalization of the two molecules 72h post exposure indicating that the laminin γ2 was misfolded after SM exposure and trapped within the ER. Taken together, these data show that ER stress is induced in mouse skin within 24h of vesicant exposure in a defensive response to promote cell survival; however, it appears that this response is rapidly overwhelmed by the apoptotic pathway as a consequence of severe SM-induced injury.

Characterization of acute and long-term pathologies of superficial and deep dermal sulfur mustard skin lesions in the hairless guinea pig model

Sulfur mustard induces severe acute and prolonged damage to the skin and only partially effective treatments are available. We have previously validated the use of hairless guinea pigs as an experimental model for skin lesions. The present study aimed to characterize a model of a deep dermal lesion and to compare it with the previously described superficial lesion. Clinical evaluation of the lesions was conducted using reflectance colorimetry, trans-epidermal water loss and wound area measurements. Prostaglandin E(2) content, matrix metalloproteinase-2 and 9 activity, and histopathology were conducted up to 4 weeks post-exposure. Sulfur mustard skin injury, including erythema and edema, impairment of skin barrier and wounds developed in a dose-dependent manner. Prostaglandin E(2) content and matrix metalloproteinase-2 and 9 activities were elevated during the wound development and the healing process. Histological evaluation revealed severe damage to the epidermis and deep dermis and vesications. At 4 weeks postexposure, healing was not completed: significantly impaired stratum corneum, absence of hair follicles, and epidermal hyperplasia were observed. These results confirm the use of the superficial and deep dermal skin injuries in the hairless guinea pigs as suitable models that can be utilized for the investigation of the pathological processes of acute as well as long-term injuries. These models will be further used to develop treatments to improve the healing process and prevent skin damage and long-term effects.

Treatment of neuroterrorism

Bioterrorism is defined as the intentional use of biological, chemical, nuclear, or radiological agents to cause disease, death, or environmental damage. Early recognition of a bioterrorist attack is of utmost importance to minimize casualties and initiate appropriate therapy. The range of agents that could potentially be used as weapons is wide, however, only a few of these agents have all the characteristics making them ideal for that purpose. Many of the chemical and biological weapons can cause neurological symptoms and damage the nervous system in varying degrees. Therefore, preparedness among neurologists is important. The main challenge is to be cognizant of the clinical syndromes and to be able to differentiate diseases caused by bioterrorism from naturally occurring disorders. This review provides an overview of the biological and chemical warfare agents, with a focus on neurological manifestation and an approach to treatment from a perspective of neurological critical care.

Mechanisms of sulfur mustard analog 2-chloroethyl ethyl sulfide-induced DNA damage in skin epidermal cells and fibroblasts

Employing mouse skin epidermal JB6 cells and dermal fibroblasts, here we examined the mechanisms of DNA damage by 2-chloroethyl ethyl sulfide (CEES), a monofunctional analog of sulfur mustard (SM). CEES exposure caused H2A.X and p53 phosphorylation as well as p53 accumulation in both cell types, starting at 1h, that was sustained for 24h, indicating a DNA-damaging effect of CEES, which was also confirmed and quantified by alkaline comet assay. CEES exposure also induced oxidative stress and oxidative DNA damage in both cell types, measured by an increase in mitochondrial and cellular reactive oxygen species and 8-hydroxydeoxyguanosine levels, respectively. In the studies distinguishing between oxidative and direct DNA damage, 1h pretreatment with glutathione (GSH) or the antioxidant Trolox showed a decrease in CEES-induced oxidative stress and oxidative DNA damage. However, only GSH pretreatment decreased CEES-induced total DNA damage measured by comet assay, H2A.X and p53 phosphorylation, and total p53 levels. This was possibly due to the formation of GSH-CEES conjugates detected by LC-MS analysis. Together, our results show that CEES causes both direct and oxidative DNA damage, suggesting that to rescue SM-caused skin injuries, pleiotropic agents (or cocktails) are needed that could target multiple pathways of mustard skin toxicities.

Pathological studies on the protective effect of a macrolide antibiotic, roxithromycin, against sulfur mustard inhalation toxicity in a rat model

Macrolide antibiotics have been shown to protect airway epithelial cells and macrophages from sulfur mustard (SM)-induced cytotoxicity. In the current study, the efficacy of roxithromycin in ameliorating SM-induced respiratory injury was further evaluated in a rat model. Anesthetized rats (N = 8/group) were intratracheally exposed to SM by vapor inhalation. For the drug treatment groups, rats were orally given 10, 20, or 40 mg/kg roxithromycin one hr prior to exposure and every twenty-four hr thereafter. After one, three, or seven days of treatment, sections of the lung were examined and scored for histopathological parameters. Treatment with roxithromycin ameliorated many of the symptoms caused by SM in some animals. In particular, treatment at 40 mg/kg for three days showed significant improvements (p < .05) over the untreated group. When the evaluation was focused on trachea, treatment with roxithromycin for three days showed a trend of dose-dependent protection; moreover, the groups treated with 20 or 40 mg/kg of roxithromycin were statistically different (p < .001 and p < .05, respectively) from the untreated group. These results suggest that roxithromycin protects against some damages associated with SM injury in the lung, particularly in the upper respiratory tract.

A case control study of cardiovascular health in chemical war disabled Iranian victims

Background:

Sulfur mustard (SM) is an alkylating chemical warfare agent that was widely used during Iran–Iraq war between 1983 and 1988. SM exposure leads to various late complications. The aim of this study was to determine the late cardiovascular effects of SM in war-disabled Iranian victims.

Materials and Methods:

This was a retrospective cohort case control study on 50 patients with symptoms of SM exposure and 50 cases who had been in Iran–Iraq war, without chemical injury. We performed exercise stress test and echocardiography for all of patients.

Results:

The study group comprised 100 males of mean age 45.6 ± 6.2 years. In chemical war injury group, two patients (4%) had positive exercise stress test. On coronary angiography, they were found to have coronary artery disease. One patient had severe mitral regurgitation and normal coronary angiography; he was referred for mitral valve replacement. Left ventricular (LV) diastolic abnormality was detected in 23% of these subjects. In another group, 5% had LV diastolic abnormality (P = 0.02) and all of them had normal stress test.

Conclusions:

Cardiovascular abnormalities are another late complication in chemical war disabled Iranian victims. Diastolic dysfunction was the most common abnormality in both groups of patients.

Sulfur mustard analog, 2-chloroethyl ethyl sulfide-induced skin injury involves DNA damage and induction of inflammatory mediators, in part via oxidative stress, in SKH-1 hairless mouse skin

Bifunctional alkyalating agent, sulfur mustard (SM)-induced cutaneous injury is characterized by inflammation and delayed blistering. Our recent studies demonstrated that 2-chloroethyl ethyl sulfide (CEES), a monofunctional analog of SM that can be used in laboratory settings, induces oxidative stress. This could be the major cause of the activation of Akt/MAP kinase and AP1/NF-κB pathways that are linked to the inflammation and microvesication, and histopathological alterations in SKH-1 hairless mouse skin. To further establish a link between CEES-induced DNA damage and signaling pathways and inflammatory responses, skin samples from mice exposed to 2 mg or 4 mg CEES for 9-48 h were subjected to molecular analysis. Our results show a strong CEES-induced phosphorylation of H2A.X and an increase in cyclooxygenase-2 (COX-2), inducible NOS (iNOS), and matrix metalloproteinase-9 (MMP-9) levels, indicating the involvement of DNA damage and inflammation in CEES-induced skin injury in male and female mice. Since, our recent studies showed reduction in CEES-induced inflammatory responses by glutathione (GSH), we further assessed the role of oxidative stress in CEES-related DNA damage and the induction of inflammatory molecules. Oral GSH (300 mg/kg) administration 1h before CEES exposure attenuated the increase in both CEES-induced H2A.X phosphorylation (59%) as well as expression of COX-2 (68%), iNOS (53%) and MMP-9 (54%). Collectively, our results indicate that CEES-induced skin injury involves DNA damage and an induction of inflammatory mediators, at least in part via oxidative stress. This study could help in identifying countermeasures that alone or in combination, can target the unveiled pathways for reducing skin injury in humans by SM.

Structural changes in the skin of hairless mice following exposure to sulfur mustard correlate with inflammation and DNA damage

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.