Serum matrix metalloproteinase levels in patients exposed to sulfur mustard

Methimazole, an Effective Neutralizing Agent of the Sulfur Mustard Derivative 2-Chloroethyl Ethyl Sulfide

Sulfur mustard (SM), designated by the military as HD, is a highly toxic and dangerous vesicant that has been utilized as a chemical warfare agent since World War I. Despite SM's extensive history, an effective antidote does not exist. The effects of SM are predominantly based on its ability to alkylate important biomolecules. Also, with the potential for a fraction of SM to remain unreacted up to days after initial contact, a window of opportunity exists for direct neutralization of unreacted SM over the days following exposure. In this study, we evaluated the structure-activity relationship of multiple nucleophilic molecules to neutralize the toxic effects of 2-chloroethyl ethyl sulfide (CEES), a monofunctional analogue of SM, on human keratinocyte (HaCaT) cells. Cell viability, relative loss of extracellular matrix adhesions, and apoptosis caused by CEES were measured via MTT, cell-matrix adhesion (CMA), and apoptosis protein marker assays, respectively. A set of five two-carbon compounds with various functional groups served as a preliminary group of first-generation neutralizing agents to survey the correlation between mitigation of CEES's toxic effects and functional group nucleophilicity. Apart from thioacids, which produced additive toxicity, we generally observed the trend of increasing protection from cytotoxicity with increasing nucleophilicity. We extended this treatment strategy to second-generation agents which contained advantageous structural features identified from the first-generation molecules. Our results show that methimazole (MIZ), a currently FDA-approved drug used to treat hyperthyroidism, effectively reduced cytotoxicity, increased CMA, and decreased apoptosis resulting from CEES toxicity. MIZ selectively reacts with CEES to produce 2-(2-(ethylthio)ethylthio)-1-methyl-1H-imidazole (EEMI) in media and cell lysate treatments resulting in the reduction of toxicity. Based on these results, future development of MIZ as an SM therapeutic may provide a viable approach to reduce both the immediate and long-term toxicity of SM and may also help mitigate slower developing SM toxicity due to residual intact SM.

The predictive association between radiological findings and lung cancer development in patients exposed to sulfur mustard gas: 4 decades follow up of 719 victims

BACKGROUND

Respiratory diseases are the leading cause of morbidity and mortality in the survivors exposed to Sulfur Mustard (SM). The late abnormalities can be present as chronic bronchitis, tracheobronchial stenosis, asthma, bronchiectasis, airway narrowing, lung fibrosis, and lung cancers. This study aims to investigate the association between radiological findings and lung cancer development in patients exposed to sulfur mustard gas.

METHODS

We entered 719 victims exposed to SM during the Iran-Iraq war into our follow-up study in a consensus manner. They were periodically followed with Chest HRCT scans from 2001 to an interval of 2014-2019. The mean year interval between exposure and the last follow-up was 38 years. For confirming the lung cancer in those with evidence of malignancy in their imaging, fine needle aspiration/biopsy and/or surgical intervention were done.

RESULTS

Among 719 patients, 57% were free from any pathologic findings in their HRCT scan. Among the subjects who had the abnormal radiologic findings, Air Trapping (AT), Lung Fibrosis (LF), Bronchiectasis (B), and the evidence of lung cancer were found in 265 (36.9%), 207 (28.8%), 151 (21.0%), and 42 (5.8%), respectively. Adenocarcinoma (38.1%) was the most common type of cancer. The right lung was involved more than the left one regarding LF, B, and cancer (p value < 0.05). Considering the laterality, a significant correlation was found between the side of LF and B and the tumor side. Furthermore, it was shown that the lung lobes with LF were statistically correlated to tumor-involved lobes. The relative risk of AT and B existence for tumor development was 11.73 [4.87-28.26] and 10.14 [5.12-20.090], respectively. The most predictive finding was LF which caused the risk of developing tumor 17.75 [7.35-42.86] times higher in the patient with this pathology. By each increment of the number of LF and B, the risk of developing tumors increased by 51% and 76%, respectively.

CONCLUSION

In survivors exposed to Sulfur Mustard, those with bronchiectasis and lung fibrosis have a significantly higher risk of developing lung cancers, so a close follow-up of these victims is recommended. Trial registration This study was confirmed by the institutional review board and ethics committee at Shiraz University of Medical Sciences (SUMS) with the ethical code IR.SUMS.MED.REC.1399.637.

Effect of dexamethasone treatment at variable therapeutic windows in reversing nitrogen mustard-induced corneal injuries in rabbit ocular in vivo model

Nitrogen mustard (NM) is an analogue of the potent vesicating agent sulfur mustard, with well-established ocular injury models in rabbit eyes to study vesicant-induced ocular toxicity. The effects of NM-exposure to eyes may include irritation, redness, inflammation, fibrosis, epithelial degradation, blurred vision, partial/complete blindness, which may be temporary or permanent, depending on the route, duration, and dosage of exposure. Effective countermeasures against vesicant exposure are presently not available and are warranted in case of any terrorist activity or accidental leakage from stockpiles. Herein, our focus was to evaluate whether dexamethasone (DEX), an FDA approved potent corticosteroid with documented anti-inflammatory activities, could be an effective treatment modality. Accordingly, utilizing NM-induced corneal injuries in rabbit ocular in vivo model, we examined and compared the efficacy of DEX treatments when administration was started at early (2 h), intermediate (4 h), and late (6 h) therapeutic windows of intervention after NM-exposure and administered every 8 h thereafter. The effects of NM-exposure and DEX treatments were evaluated on clinical (corneal opacity, ulceration, and neovascularization), biological (epithelial thickness, epithelial-stromal separation, blood vessels density, and inflammatory cell and keratocyte counts) and molecular (COX-2 and VEGF expression) parameters, at day 1, 3, 7 and 14. Results indicated that DEX treatment markedly and effectively reversed the NM-induced injury markers in rabbit corneas. Early administration of DEX at 2 h was found to be most effective in reversing NM-induced corneal injuries, followed by DEX 4 h and DEX 6 h administration initiation, indicating that DEX has best efficacy at the early therapeutic window in our study model.

Pathophysiology and inflammatory biomarkers of sulfur mustard-induced corneal injury in rabbits

Sulfur mustard (SM) is a cytotoxic, vesicating, chemical warfare agent, first used in 1917; corneas are particularly vulnerable to SM exposure. They may develop inflammation, ulceration, neovascularization (NV), impaired vision, and partial/complete blindness depending upon the concentration of SM, exposure duration, and bio-physiological conditions of the eyes. Comprehensive in vivo studies have established ocular structural alterations, opacity, NV, and inflammation upon short durations (<4 min) of SM exposure. In this study, detailed analyses of histopathological alterations in corneal structure, keratocytes, inflammatory cells, blood vessels, and expressions of cyclooxygenase (COX)-2, matrix metalloproteinase (MMP)-9, vascular endothelial growth factor (VEGF), and cytokines were performed in New Zealand white rabbits, in a time-dependent manner till 28 days, post longer durations (5 and 7 min) of ocular SM exposure to establish quantifiable endpoints of injury and healing. Results indicated that SM exposure led to duration-dependent increases in corneal thickness, opacity, ulceration, epithelial-stromal separation, and epithelial degradation. Significant increases in NV, keratocyte death, blood vessels, and inflammatory markers (COX-2, MMP-9, VEGF, and interleukin-8) were also observed for both exposure durations compared to the controls. Collectively, these findings would benefit in temporal delineation of mechanisms underlying SM-induced corneal toxicity and provide models for testing therapeutic interventions.

Adipose-derived mesenchymal stem cells ameliorate lung epithelial injury through mitigating of oxidative stress in mustard lung

Aim: We investigated potential efficacy of autologous adipose-derived mesenchymal stem cell (MSC) on oxidative stress (OS) and airway remodeling in patients with chronic mustard lung. Patients & methods: Ten patients received 100 × 106 cells every 20 days for 4 injections over a 2-month period. Results: A gradual improvement was observed for 6 min walk test scores, pulmonary function tests and respiratory quality after MSCs therapy. A significant decrease was found for the mean levels of Mucin-1 protein (KL-6; p = 0.022) and Clara cell protein 16 (CC16; p = 0.005). Antioxidants had a tendency to be higher after each injection. Conclusion: Our findings revealed that MSCs therapy can be safely used for improvement of lung injury and regeneration in these patients without adverse effects. Trial registration number: NCT02749448 (ClinicalTrials.gov).

A review of Sulfur Mustard-induced pulmonary immunopathology: An Alveolar Macrophage Approach

Despite many studies investigating the mechanism of Sulfur Mustard (SM) induced lung injury, the underlying mechanism is still unclear. Inflammatory and subsequent fibroproliferative stages of SM-toxicity are based upon several highly-related series of events controlled by the immune system. The inhalation of SM gas variably affects different cell populations within the lungs. Various studies have shown the critical role of macrophages in triggering a pulmonary inflammatory response as well as its maintenance, resolution, and repair. Importantly, macrophages can serve as either pro-inflammatory or anti-inflammatory populations depending on the present conditions at any pathological stage. Different characteristics of macrophages, including their differentiation, phenotypic, and functional properties, as well as interactions with other cell populations determine the outcomes of lung diseases and the extent of long- or short-term pulmonary damage induced by SM. In this paper, we summarize the current state of knowledge regarding the role of alveolar macrophages and their mediators in the pathogenesis of SM in pulmonary injury. Investigating the specific cells and mechanisms involved in SM-lung injury may be useful in finding new target opportunities for treatment of this injury.

Advances in treatment of acute sulfur mustard poisoning - a critical review

Sulfur mustard (SM) is a blistering chemical warfare agent that was used during the World War I and in the Iraq-Iran conflict. The aim of this paper is to discuss and critically review the published results of experiments on the treatment of SM poisoning based on our clinical and research experience. The victims must remove from the contaminated zone immediately. The best solution for decontamination is large amounts of water, using neutral soap and 0.5% sodium hypochlorite. Severely intoxicated patients should be treated according to advanced life support protocols and intensive care therapy for respiratory disorders and the chemical burn. Sodium thiosulfate infusion (100-500 mg/kg/min) should be started up to 60 min after SM exposure. However, N-acetyle cysteine (NAC) is recommended, none of them acts as specific or effective antidote. The important protective and conservative treatment of SM-induced pulmonary injuries include humidified oxygen, bronchodilators, NAC as muculytic, rehydration, mechanical ventilation, appropriate antibiotics and respiratory physiotherapy as clinically indicated. Treatment of acute SM ocular lesions start with topical antibiotics; preferably sulfacetamide eye drop, continue with lubricants, and artificial tears. Treatment for cutaneous injuries include: moist dressing; preferably with silver sulfadiazine cream, analgesic, anti-pruritic, physically debridement, debridase, Laser debridement, followed by skin autologous split-thickness therapy as clinically indicated. The new suggested medications and therapeutic approaches include: anti-inflammatory agents, Niacinamide, Silibinin, Calmodulin antagonists, Clobetasol, full-thickness skin grafting for skin injuries; Doxycycline; Bevacizumab, and Colchicine for ocular injuries. Recommended compounds based on animal studies include Niacinamide, Aprotinin, des-aspartate-angiotensin-I, Gamma-glutamyltransferase, vitamin E, and vitamin D. In vitro studies revealed that Dimethylthiourea, L-nitroarginine, Methyl-ester, Sodium pyruvate, Butylated hydroxyanisole, ethacrynic acid, and macrolide antibiotics are effective. However, none of them, except macrolide antibiotics have been proved clinically. Avoidance of inappropriate polypharmacy is advisable.

NAD+ in sulfur mustard toxicity

Sulfur mustard (SM) is a toxicant and chemical warfare agent with strong vesicant properties. The mechanisms behind SM-induced toxicity are not fully understood and no antidote or effective therapy against SM exists. Both, the risk of SM release in asymmetric conflicts or terrorist attacks and the usage of SM-derived nitrogen mustards as cancer chemotherapeutics, render the mechanisms of mustard-induced toxicity a highly relevant research subject. Herein, we review a central role of the abundant cellular molecule nicotinamide adenine dinucleotide (NAD⁺) in molecular mechanisms underlying SM toxicity. We also discuss the potential beneficial effects of NAD⁺ precursors in counteracting SM-induced damage.

Acute corneal injury in rabbits following nitrogen mustard ocular exposure

Sulfur mustard (SM), a potent vesicating chemical warfare agent, and its analog nitrogen mustard (NM), are both strong bi-functional alkylating agents. Eyes, skin, and the respiratory system are the main targets of SM and NM exposure; however, ocular tissue is most sensitive, resulting in severe ocular injury. The mechanism of ocular injury from vesicating agents' exposure is not completely understood. To understand the injury mechanism from exposure to vesicating agents, NM has been previously employed in our toxicity studies on primary human corneal epithelial cells and ex vivo rabbit cornea organ culture model. In the current study, corneal toxicity from NM ocular exposure (1%) was analyzed for up to 28 days post-exposure in New Zealand White male rabbits to develop an acute corneal injury model. NM exposure led to conjunctival and eyelid swelling within a few hours after exposure, in addition to significant corneal opacity and ulceration. An increase in total corneal thickness and epithelial degradation was observed starting at day 3 post-NM exposure, which was maximal at day 14 post-exposure and did not resolve until 28 days post-exposure. There was an NM-induced increase in the number of blood vessels and inflammatory cells, and a decrease in keratocytes in the corneal stroma. NM exposure resulted in increased expression levels of cyclooxygenase-2, Interleukin-8, vascular endothelial growth factor and Matrix Metalloproteinase 9 indicating their involvement in NM-induced corneal injury. These clinical, biological, and molecular markers could be useful for the evaluation of acute corneal injury and to screen for therapies against NM- and SM-induced ocular injury.

The systemic nature of mustard lung: Comparison with COPD patients

Sulphur mustard (SM) is a powerful blister-causing alkylating chemical warfare agent used by Iraqi forces against Iran. One of the known complications of mustard gas inhalation is mustard lung which is discussed as a phenotype of chronic obstructive pulmonary disease (COPD). In this complication, there are clinical symptoms close to COPD with common etiologies, such as in smokers. Based on information gradually obtained by conducting the studies on mustard lung patients, systemic symptoms along with pulmonary disorders have attracted the attention of researchers. Changes in serum levels of inflammatory markers, such as C-reactive protein (CRP), tumor necrosis factor alpha (TNF-α), nuclear factor κB (NF-κB), matrix metalloproteinases (MMPs), interleukin (IL), chemokines, selectins, immunoglobulins, and signs of imbalance in oxidant-antioxidant system at serum level, present the systemic changes in these patients. In addition to these, reports of extra-pulmonary complications, such as osteoporosis and cardiovascular disease are also presented. In this study, the chance of developing the systemic nature of this lung disease have been followed on using the comparative study of changes in the mentioned markers in mustard lung and COPD patients at stable phases and the mechanisms of pathogenesis and phenomena, such as airway remodeling in these patients.

Evaluation of Association Between the Serum Levels of MMP-9 and MMP-9/TIMPs With Soluble Forms of Selectins and Itching Induced by Sulfur Mustard

BACKGROUND & OBJECTIVE

Pruritus is the most frequent chronic dermal complication of sulfur mustard (SM), which negatively influences the quality of life. Exact pathophysiology of SM-induced itching is unknown. The current study aimed at evaluating the possible association between SM-induced itching and the serum levels of matrix metalloproteinase (MMP)-9 and their endogenous inhibitors, and serum levels of soluble forms of selectins (sL-, sP-, and sE-selectins) as adhesion molecules involved in the development of different inflammatory reactions.

METHODS

Serum levels of MMP-9, MMP-9/ tissue inhibitors of metalloproteinases (TIMPs), and selectins were measured by the enzyme-linked immunosorbent assay (ELISA), and compared between the groups (n=368) with and without itching, and matched control groups (n=126).

RESULTS

Serum levels of MMP-9 were significantly higher in the SM exposed group with itching, compared with that of the group without itching (medians: 894 and 624 pg/mL respectively; P-value =0.034). There was no relationship between the serum levels of MMP-9/TIMP-1, MMP-9/TIMP-2, MMP-9/TIMP-4, and itching in the patients exposed to SM. Median serum levels of sE- and sL-selectins in the exposed group with itching were higher than those of the exposed group without itching. These differences were statistically insignificant (P-values =0.084 and 0.095, respectively).

CONCLUSION

According to the results of the current study, the increased serum levels of MMP-9 and selectins 20 years after exposure may play role in the pathogenesis and persistence of SM-induced itching in the exposed individuals.

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.

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.

Respiratory effects of sulfur mustard exposure, similarities and differences with asthma and COPD

CONTEXT

Previous research has found relationships between sulfur mustard (SM) toxicity and its adverse effects.

OBJECTIVE

SM is highly toxic to the respiratory system, leading to hacking cough, rhinorrheachest tightness, acute pharyngitis and laryngitis, chronic bronchitis and lung fibrosis. In this review, based on the scientific literature, we provide an updated summary of information on SM exposures and their differences with asthma and COPD.

METHOD

Information of this review was obtained by searching Medline/PubMed, ScienceDirect, Scopus, Google Scholar, ISI Web of Knowledge and Chemical Abstracts.

RESULTS

SM exposure can decrease pulmonary function tests (PFTs) values. In addition, inflammatory cell accumulation in the respiratory tract and increased expression of some pro-inflammatory cytokines including tumor necrosis factor-α (TNFα), IL-1a, IL-1β, and reactive oxygen radicals due to SM exposure have been shown. Matrix metalloproteinase (MMP) which degrade extracellular matrix proteins, contributing to inflammatory cell recruitment, tissue injury and fibrosis are also up-regulated in the lung after SM exposure. In the lung, SM exposure also can cause serious pathological changes including airway inflammation, parenchymal tissue destruction and airway obstruction which can lead to asthma or chronic obstructive pulmonary disease (COPD). Following SM poisoning, DNA damage, apoptosis and autophagy are observed in the lung along with the increased expression of activated caspases and DNA repair enzymes.

CONCLUSION

In the present article, respiratory symptoms, changes in PFTs, lung pathology and lung inflammation due to SM exposure and the similarities and differences between them and those observed in asthma and COPD were reviewed.