Evidence for the systemic diffusion of (2-chloroethyl)-ethyl-sulfide, a sulfur mustard analog, and its deleterious effects in brain.

Sulfur mustard, a chemical warfare agent known to be a vesicant of skin, readily diffuses in the blood stream and reaches internal organs. In the present study, we used the analog (2-chloroethyl)-ethyl-sulfide (CEES) to provide novel data on the systemic diffusion of vesicants and on their ability to induce brain damage, which result in neurological disorders. SKH-1 hairless mice were topically exposed to CEES and sacrificed at different time until 14 days after exposure. A plasma metabolomics study showed a strong systemic impact following a self-protection mechanism to alleviate the injury of CEES exposure. This result was confirmed by the quantification of specific biomarkers in plasma. Those were the conjugates of CEES with glutathione (GSH-CEES), cysteine (Cys-CEES) and N-acetyl-cysteine (NAC-CEES), as well as the guanine adduct (N7Gua-CEES). In brain, N7Gua-CEES could be detected both in DNA and in organ extracts. Similarly, GSH-CEES, Cys-CEES and NAC-CEES were present in the extracts until day14. Altogether, these results, based on novel exposure markers, confirm the ability of vesicants to induce internal damage following dermal exposure. The observation of alkylation damage to glutathione and DNA in brain provides an additional mechanism to the neurological insult of SM.

Pulmonary injury and oxidative stress in rats induced by inhaled sulfur mustard is ameliorated by anti-tumor necrosis factor-α antibody.

Sulfur mustard (SM) is a bifunctional alkylating agent that causes severe injury to the respiratory tract. This is accompanied by an accumulation of macrophages in the lung and the release of the proinflammatory cytokine, tumor necrosis factor (TNF)α. In these studies, we analyzed the effects of blocking TNFα on lung injury, inflammation and oxidative stress induced by inhaled SM. Rats were treated with SM vapor (0.4 mg/kg) or air control by intratracheal inhalation. This was followed 15-30 min later by anti-TNFα antibody (15mg/kg, i.v.) or PBS control. Animals were euthanized 3 days later. Anti-TNFα antibody was found to blunt SM-induced peribronchial edema, perivascular inflammation and alveolar plasma protein and inflammatory cell accumulation in the lung; this was associated with reduced expression of PCNA in histologic sections and decreases in BAL levels of fibrinogen. SM-induced increases in inflammatory proteins including soluble receptor for glycation end products, its ligand, high mobility group box-1, and matrix metalloproteinase-9 were also reduced by anti-TNFα antibody administration, along with increases in numbers of lung macrophages expressing TNFα, cyclooxygenase-2 and inducible nitric oxide synthase. This was correlated with reduced oxidative stress as measured by expression of heme oxygenase-1 and Ym-1. Together, these data suggest that inhibiting TNFα may represent an efficacious approach to mitigating acute lung injury, inflammatory macrophage activation, and oxidative stress induced by inhaled sulfur mustard.

Dose-dependent emergence of acute and recurrent corneal lesions in sulfur mustard-exposed rabbit eyes.

Sulfur mustard (SM) is a lipid soluble alkylating agent that causes genotoxic injury. The eye is highly sensitive to SM toxicity and exposures exceeding 400 mg min/m3 can elicit irreversible corneal pathophysiologies. Development of medical countermeasures for ocular SM exposure has been hindered by a limited understanding of dose-dependent effects of SM on corneal injury. Here, clinical, histological and ultrastructural analyses were used to characterize the effects of SM dose on corneal injury progression. Corneas were evaluated for up to 20 wk following exposure to saturated SM vapor for 30-150 s, which corresponds to 300-1,500 mg min/m3. In acute studies, a ceiling effect on corneal edema developed at doses associated with full-thickness corneal lesions, implicating endothelial toxicity in corneal swelling. Recurrent edematous lesions (RELs) transiently emerged after 2 wk in a dose-dependent fashion, followed by the development of secondary corneal pathophysiologies such as neovascularization, stromal scarring and endothelial abnormalities. RELs appeared in 96 % of corneas exposed for ≥ 90 s, 52 % of corneas exposed for 60 s and 0 % of corneas exposed for 30 s. While REL latency was variable in corneas exposed for 60 s, REL emergence was synchronized at exposures ≥ 90 s. Corneas did not exhibit more than one REL, suggesting RELs are part of a programmed pathophysiological response to severe alkylating lesions. In post-mortem studies at 12 wk, corneal edema was positively correlated to severity of endothelial pathologies, consistent with previous findings that endothelial toxicity influences long-term outcomes. These results provide novel insight into long-term corneal pathophysiological responses to acute toxicity and identify exposure conditions suitable for therapeutic testing.

A novel exposure system generating nebulized aerosol of sulfur mustard in comparison to the standard submerse exposure.

Inhalation of the chemical warfare agent sulfur mustard (SM) is associated with severe acute and long-term pulmonary dysfunctions and health effects. The still not completely elucidated molecular toxicology and a missing targeted therapy emphasize the need for further research. However, appropriate human data are extremely rare. In vivo animal experiments are often regarded as gold standard in toxicology but may exhibit significant differences compared to the human pulmonary anatomy and physiology. Thus, alternative in vitro exposure methods, adapted to the human in vivo situation by exposing cells at the air-liquid interface (ALI), are complimentary approaches at a cellular level. So far, it is unclear whether the enhanced experimental complexity of ALI exposure, that is potentially biologically more meaningful, is superior to submerged exposures which are typically performed. Aim of our study was the evaluation of an appropriate in vitro exposure system (CULTEX® Radial Flow System (RFS) equipped with an eFlow® membrane nebulizer) for the exposure of cultivated human lung cells (A549) with SM under ALI conditions. Cellular responses (i.e. cell viability) and formation of SM-specific DNA-adducts were investigated and compared between ALI and submerse SM exposures. Our results proved the safe applicability of our ALI exposure system setup. The aerosol generation and subsequent deposition at the ALI were stable and uniform. The technical CULTEX® RFS setup is based on ALI exposure with excess of aerosol from that only some is deposited on the cell layer. As expected, a lower cytotoxicity and DNA-adduct formation were detected when identical SM concentrations were used compared to experiments under submerged conditions. A distinct advantage of SM-ALI compared to SM-submerse exposures could not be found in our experiments. Though, the CULTEX® RFS was found suitable for SM-ALI exposures.

Inter strand crosslinks in DNA induced in vivo by percutaneous application of sulphur mustard to rats and mice.

Inter-strand crosslinks (ICL) in the DNA are regarded to be the main toxic lesions induced by sulphur mustard (SM). We have followed the induction of ICL in the DNA of different organs of Wistar rats and Balb/c or NMRI mice by the percutaneous application of SM using the modified (reverse) comet assay. Significant amounts of ICL were found in Balb/C lymphocytes, in bone marrow and liver cells after the dose of 80 mg/kg. A dose-dependent amount of ICL was induced in rats, with efficient induction in lymphocytes and spleen cells already after 5 mg SM/kg, indicating a higher susceptibility of rats to the DNA-damaging effect of SM compared with mice. A significant induction of ICL in other tested tissues (liver, bone marrow, colon epithelium) was seen at the dose of 20 mg/kg. The induced ICL were removed from the DNA during 48 h except for rats at the dose of 80 mg/kg. In fact, we observed that ICL are almost completely repaired in tissues of rats receiving high lethal doses. Results suggest that the unhooking of ICL, which we followed with the comet assay, may lead to the formation of another toxic DNA lesion during the repair process.

Bronchiolitis Obliterans and Pulmonary Fibrosis after Sulfur Mustard Inhalation in Rats.

Inhalation of powerful chemical agents, such as sulfur mustard (SM), can have debilitating pulmonary consequences, such as bronchiolitis obliterans (BO) and parenchymal fibrosis (PF). The underlying pathogenesis of disorders after SM inhalation is not clearly understood, resulting in a paucity of effective therapies. In this study, we evaluated the role of profibrotic pathways involving transforming growth factor-ß (TGF-ß) and platelet-derived growth factor (PDGF) in the development of BO and PF after SM inhalation injury using a rat model. Adult Sprague-Dawley rats were intubated and exposed to SM (1.0 mg/kg), then monitored daily for respiratory distress, oxygen saturation changes, and weight loss. Rats were killed at 7, 14, 21, or 28 days, and markers of injury were determined by histopathology; pulmonary function testing; and assessment of TGF-ß, PDGF, and PAI-1 concentrations. Respiratory distress developed over time after SM inhalation, with progressive hypoxemia, respiratory distress, and weight loss. Histopathology confirmed the presence of both BO and PF, and both gradually worsened with time. Pulmonary function testing demonstrated a time-dependent increase in lung resistance, as well as a decrease in lung compliance. Concentrations of TGF-ß, PDGF, and PAI-1 were elevated at 28 days in lung, BAL fluid, and/or plasma. Time-dependent development of BO and PF occurs in lungs of rats exposed to SM inhalation, and the elevated concentrations of TGF-ß, PDGF, and PAI-1 suggest involvement of these profibrotic pathways in the aberrant remodeling after injury.

Immediate responses of the cockroach Blaptica dubia after the exposure to sulfur mustard.

The chemical agent sulfur mustard (SM) causes erythema, skin blisters, ulcerations, and delayed wound healing. It is accepted that the underlying molecular toxicology is based on DNA alkylation. With an expected delay, DNA damage causes impairment of protein biosynthesis and disturbance of cell division. However, using the cockroach model Blaptica dubia, the presented results show that alkylating compounds provoke immediate behavior responses along with fast changes in the electrical field potential (EFP) of neurons, suggesting that lesions of DNA are probably not the only effect of alkylating compounds. Blaptica dubia was challenged with SM or 2-chloroethyl-ethyl sulfide (CEES). Acute toxicity was objectified by a disability score. Physiological behavior responses (antennae pullback reflex, escape attempts, and grooming) were monitored after exposure. To estimate the impact of alkylating agents on neuronal activity, EFP recordings of the antennae and the thoracic ganglion were performed. After contact to neat SM, a pullback reflex of the antennae was the first observation. Subsequently, a striking escape behavior occured which was characterized by persistent movement of the legs. In addition, an instantaneous processing of the electrical firing pattern from the antennae to the descending ganglia was detectable. Remarkably, comparing the toxicity of the applied alkylating agents, effects induced by CEES were much more pronounced compared to SM. In summary, our findings document immediate effects of B. dubia after exposure to alkylating substances. These fast responses cannot be interpreted as a consequence of DNA alkylation. Therefore, the dogma that DNA alkylation is the exclusive cause for SM toxicity has to be questioned.

Cognitive and emotional impairments after cutaneous intoxication by CEES (a sulfur mustard analog) in mice.

Cognitive and emotional disorders have been reported in veterans intoxicated with sulfur mustard (SM) a chemical weapon belonging to the category of vesicating agents. However, the intense stress associated with the SM intoxication may render difficult determining the exact role played by SM intoxication itself on the emergence and maintaining of cognitive disorders. Animal's model would allow overcoming this issue. So far, we presently investigated the cognitive and emotional impact of an acute cutaneous intoxication with CEES (2-chloroethyl ethyl sulfide), a SM analog in C57/Bl6 mice. Our study evidenced that up to 5days after a single acute neat CEES skin exposure, compared to controls, mice exhibited i) a significant increase in anxiety-like reactivity in an elevated plus-maze and in an open-field tasks and ii) an alteration of working memory in a sequential alternation task. In contrast, mice submitted to intoxication with a diluted CEES solution or hydrochloric acid (HCl) did not show any memory or emotional impairments. Given that, Our data shows that a single local cutaneous intoxication with neat CEES induced long-lasting cognitive and emotional pejorative effects, in accordance with the epidemiological observations in veterans. Thus, the single acute neat CEES cutaneous intoxication in mice could allow studying the sulfur mustard-induced cognitive and emotional disorders and their further counter-measures.

Editor's Highlight: Pulmonary Vascular Thrombosis in Rats Exposed to Inhaled Sulfur Mustard.

Sulfur mustard (SM) is a chemical warfare agent. When inhaled, SM causes significant injury to the respiratory tract. Although the mechanism involved in acute airway injury after SM inhalation has been well described previously, the mechanism of SM's contribution to distal lung vascular injury is not well understood. We hypothesized that acute inhalation of vaporized SM causes activated systemic coagulation with subsequent pulmonary vascular thrombi formation after SM inhalation exposure. Sprague Dawley rats inhaled SM ethanolic vapor (3.8 mg/kg). Barium/gelatin CT pulmonary angiograms were performed to assess for pulmonary vascular thrombi burden. Lung immunohistochemistry was performed for common procoagulant markers including fibrin(ogen), von Willebrand factor, and CD42d in control and SM-exposed lungs. Additionally, systemic levels of d-dimer and platelet aggregometry after adenosine diphosphate- and thrombin-stimulation were measured in plasma after SM exposure. In SM-exposed lungs, chest CT angiography demonstrated a significant decrease in the distal pulmonary vessel density assessed at 6 h postexposure. Immunohistochemistry also demonstrated increased intravascular fibrin(ogen), vascular von Willebrand factor, and platelet CD42d in the distal pulmonary vessels (<200 µm diameter). Circulating d-dimer levels were significantly increased (p < .001) at 6, 9, and 12 h after SM inhalation versus controls. Platelet aggregation was also increased in both adenosine diphosphate - (p < .01) and thrombin- (p < .001) stimulated platelet-rich plasma after SM inhalation. Significant pulmonary vascular thrombi formation was evident in distal pulmonary arterioles following SM inhalation in rats assessed by CT angiography and immunohistochemistry. Enhanced systemic platelet aggregation and activated systemic coagulation with subsequent thrombi formation likely contributed to pulmonary vessel occlusion.

In vitro the differences of inflammatory and oxidative reactions due to sulfur mustard induced acute pulmonary injury underlying intraperitoneal injection and intratracheal instillation in rats.

This study was to investigate the differences of inflammatory reaction and oxidative stress due to sulfur mustard (SM)-induced acute pulmonary injury via two ways in rats. In intraperitoneal and tracheal SM groups, injected intraperitoneally and instilled intratracheally with 0.1mL diluted SM (0.96 LD50=8mg/kg) and SM (0.98 LD50=2mg/kg) were administered in rats. In bronchoalveolar lavage fluid, serum, and alveolar septum, lactate dehydrogenase, glutathione peroxidase, tumor necrosis factor-α, interleukin-1ß, interleukin-6, C-reactive protein, intercellular adhesion molecule-1, vascular cell adhesion molecule-1, l-selectin, r-glutamyl transpeptidase, thiobarbituric acid reactive substances levels as well as the expression of CD4, CD20, CD68, 8-hydroxy deoxyguanosine, nuclear factor-E2-related factor 2, and heme oxygenase-1 measured by ELISA, immune scatter turbidimetry and immunohistochemical method in the intraperitoneal SM group were increased at each time-point compared with the tracheal SM groups, respectively. These data demonstrated an increased inflammatory reaction and oxidative stress indices in rat via intraperitoneal injection under similar SM LD50 doses.

N-Acetyl-L-cysteine inhibits sulfur mustard-induced and TRPA1-dependent calcium influx.

Transient receptor potential family channels (TRPs) have been identified as relevant targets in many pharmacological as well as toxicological studies. TRP channels are ubiquitously expressed in different tissues and act among others as sensors for different external stimuli, such as mechanical stress or noxious impacts. Recent studies suggest that one member of this family, the transient receptor potential ankyrin 1 cation channel (TRPA1), is involved in pain, itch, and various diseases, suggesting TRPA1 as a potential therapeutic target. As a nociceptor, TRPA1 is mainly activated by noxious or electrophilic compounds, including alkylating substances. Previous studies already revealed an impact of 2-chloroethyl-ethyl sulfide on the ion channel TRPA1. In this study, we demonstrate that sulfur mustard (bis-(2-chloroethyl) sulfide, SM) activates the human TRPA1 (hTRPA1) in a dose-dependent manner measured by the increase in intracellular Ca2+ concentration ([Ca2+]i). Besides that, SM-induced toxicity was attenuated by antioxidants. However, very little is known about the underlying mechanisms. Here, we demonstrate that N-acetyl-L-cysteine (NAC) prevents SM-induced hTRPA1-activation. HEK293-A1-E cells, overexpressing hTRPA1, show a distinct increase in [Ca2+]i immediately after SM exposure, whereas this increase is reduced in cells pretreated with NAC in a dose-dependent manner. Interestingly, glutathione, although being highly related to NAC, did not show an effect on hTRPA1 channel activity. Taken together, our results provide evidence that SM-dependent activation of hTRPA1 can be diminished by NAC treatment, suggesting a direct interaction of NAC and the hTRPA1 cation channel. Our previous studies already showed a correlation of hTRPA1-activation with cell damage after exposure to alkylating agents. Therefore, NAC might be a feasible approach mitigating hTRPA1-related dysregulations after exposure to SM.

Acute Gene Expression Profile of Lung Tissue Following Sulfur Mustard Inhalation Exposure in Large Anesthetized Swine.

Sulfur mustard (HD) is a vesicating and alkylating agent widely used on the battlefield during World War I and more recently in the Iran-Iraq War. It targets the eyes, skin, and lungs, producing skin burns, conjunctivitis, and compromised respiratory function; early acute effects lead to long-term consequences. However, it is the effects on the lungs that drive morbidity and eventual mortality. The temporal postexposure response to HD within lung tissue raises the question of whether toxicity is driven by the alkylating properties of HD on critical homeostatic pathways. We have established an anesthetized swine model of inhaled HD vapor exposure to investigate the toxic effects of HD 12 h postexposure. Large white female swine were anesthetized and instrumented prior to exposure to air, 60 (sublethal) or 100 µg·kg-1 (∼LD40) doses of HD (10 min). Physiological parameters were continuously assessed. Data indicate that exposure to 100 µg·kg-1 HD lowered arterial blood oxygenation and increased shunt fraction and lavage protein compared with those of air-exposed controls and the 60 µg·kg-1 dose of HD. Histopathology showed an increased total pathology score between the 100 µg·kg-1 HD group and air-exposed controls. Principal component analysis of differentially expressed genes demonstrated a distinct and separable response of inhaled HD between air-exposed controls and the 60 and 100 µg·kg-1 doses of HD. Canonical pathway analysis demonstrated changes in acute phase response signaling, aryl hydrocarbon receptor signaling, NRF-2 mediated oxidative stress, and zymosterol biosynthesis in the 60 and 100 µg·kg-1 HD dose group. Transcriptional changes also indicated alterations in immune response, cancer, and cell signaling and metabolism canonical pathways. The 100 µg·kg-1 dose group also showed significant changes in cholesterol biosynthesis. Taken together, exposure to inhaled HD had a significant effect on physiological responses coinciding with acute changes in gene expression and lung histopathology. In addition, transcriptomics support the observed beneficial effects of N-acetyl-l-cysteine for treatment of acute inhalation HD exposure.

Sulfur mustard inhalation: mechanisms of injury, alteration of coagulation, and fibrinolytic therapy.

Acute lung injury due to sulfur mustard (SM) inhalation causes the formation of airway fibrin casts that obstruct airways at multiple levels, leading to acute respiratory failure and death. These pathophysiological effects are seen in rodent models of acute SM vapor inhalation, as well as in human victims of acute SM inhalation. In rat models, the initial steps in activation of the coagulation system at extravascular sites depend on tissue factor (TF) expression by airway cells, especially in the microparticle fraction, and these effects can be inhibited by TF pathway inhibitor protein. Not only does the procoagulant environment of the acutely injured lung contribute to airway cast formation, but these lesions persist in airways because of the activation of multiple antifibrinolytic pathways, including plasminogen activator inhibitor-1, thrombin-activatable fibrinolysis inhibitor, and α2-antiplasmin. Airway administration of tissue plasminogen activator can overwhelm these effects and save lives by preventing fibrin-dependent airway obstruction, gas-exchange abnormalities, and respiratory failure. In human survivors of SM inhalation, fibrotic processes, including bronchiolitis obliterans and interstitial fibrosis of the lung, are among the most disabling chronic lesions. Antifibrotic therapies may prove useful in preventing either or both of these forms of chronic lung damage.

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.

Impact of topical application of sulfur mustard on mice skin and distant organs DNA repair enzyme signature.

Sulfur mustard (SM) is a chemical warfare agent that, upon topical application, damages skin and reaches internal organs through diffusion in blood. Two major toxic consequences of SM exposure are inflammation, associated with oxidative stress, and the formation of alkylated DNA bases. In the present study, we investigated the impact of exposure to SM on DNA repair, using two different functional DNA repair assays which provide information on several Base Excision Repair (BER) and Excision/Synthesis Repair (ESR) activities. BER activities were reduced in all organs as early as 4h after exposure, with the exception of the defense systems against 8-oxo-guanine and hypoxanthine which were stimulated. Interestingly, the resulting BER intermediates could activate inflammation signals, aggravating the inflammation triggered by SM exposure and leading to increased oxidative stress. ESR activities were found to be mostly inhibited in skin, brain and kidneys. In contrast, in the lung there was a general increase in ESR activities. In summary, exposure to SM leads to a significant decrease in DNA repair in most organs, concomitant with the formation of DNA damage. These synergistic genotoxic effects are likely to participate in the high toxicity of this alkylating agent. Lungs, possibly better equipped with repair enzymes to handle exogenous exposure, are the exception.

Distribution of DNA adducts and corresponding tissue damage of Sprague-Dawley rats with percutaneous exposure to sulfur mustard.

Sulfur mustard (SM) is a highly reactive alkylation vesicant and cytotoxic agent that has been recognized as an animal and human carcinogen. Although the exact mechanism of toxicology is vague, DNA alkylation seems to be responsible for the triggering of apoptosis. In this study, after male adult Sprague-Dawley rats were cutaneous exposed to a low concentration of SM at parts-per-million levels, their lungs, livers, pancreases, spleens, marrow, and brains were collected at 11 different time points and analyzed. N7-[2-[(2-hydroxyethyl)thio]-ethyl]guanine (N7-HETEG), N3-[2-[(2-hydroxyethyl)thio]-ethyl]adenine (N3-HETEA), and bis[2-(guanin-7-yl)ethyl]sulfide (Bis-G) as the biomarkers for DNA damage were measured in the vital tissues by isotope dilution ultraperformance liquid chromatography tandem mass spectrometry (ID-UPLC-MS/MS). At the same time, general variations and pathological changes were monitored and detected to evaluate the tissue damage. Time- and dose-dependent data showed that SM had strong permeability and reactivity and that three SM-DNA adducts were detected in all investigated tissues only after 10 min after exposure. Obvious dose-dependency was observed except in the brain and pancreas. Most times to peak (tmax) of all three adducts were less than 3 h, while half-lifetimes (t1/2) were less than 24 h. We also suggested that the lipophilic SM can easily pass through the blood-brain barrier and can be stored in the fatty organs. To the best of our knowledge, the abundant adducts in marrow were found and reported for the first time. The surveillance of N7-HETEG in vivo, which was the most abundant adduct, may be the most efficient indicator to validate SM exposure even without any symptoms. Bis-G can be regarded as a biomarker of effect, which is directly related to the extent of damage. The most abundant Bis-G was found in the most sensitive tissues, marrow, spleen, and lung, which is in good accordance with histopathologic results. General variations and pathological changes were evaluated as well. After cutaneous exposure to SM, the body weights of rats heavily decreased in the first 4 days and were inversely proportional to the applied doses, and then recovered at the last experimental day except for those of the rats at the highest dosing level, in which the relative weights of rat spleens were obviously lost. Moreover, we found remarkable histological changes of the lung and skin, such as encephalemia, at the very beginning of the sampling procedure, and plentiful mononuclear cells in marrow appeared 6 h after exposure. The micronucleus test of marrow cells showed that the micronucleus rate had a positively dose-dependent effect.

A novel sulfur mustard (HD) vapor inhalation exposure system for accurate inhaled dose delivery.

INTRODUCTION: A custom designed HD exposure system was used to deliver controlled inhaled doses to an animal model through an endotracheal tube. METHODS: Target HD vapor challenges were generated by a temperature controlled bubbler/aerosol trap, while concentration was monitored near real-time by gas chromatography. Animal breathing parameters were monitored real-time by an in-line pneumotach, pressure transducer, and Buxco pulmonary analysis computer/software. For each exposure, the challenge atmosphere was allowed to stabilize at the desired concentration while the anesthetized animal was provided humidity controlled clean air. Once the target concentration was achieved and stable, a portion of the challenge atmosphere was drawn past the endotracheal tube, where the animal inhaled the exposure ad libitum. During the exposure, HD vapor concentration and animal weight were used to calculate the needed inhaled volume to achieve the target inhaled dose (µg/kg). The exposures were halted when the inhaled volume was achieved. RESULTS: The exposure system successfully controlled HD concentrations from 22.2 to 278mg/m(3) and accurately delivered inhaled doses between 49.3 and 1120µg/kg with actual administered doses being within 4% of the target level. DISCUSSION: This exposure system administers specific HD inhaled doses to evaluate physiological effects and for evaluation of potential medical countermeasure treatments.

Comparative proteome analysis of peripheral neutrophils from sulfur mustard-exposed and COPD patients.

Respiratory disorders in sulfur mustard (SM)-exposed and chronic obstructive pulmonary disease (COPD) patients are mostly associated with neutrophilic inflammation, severe airflow limitation, and oxidative stress. The objective of this study was to establish whether neutrophil (PMN) proteomes in these diseases were similar or differed. Blood neutrophil proteomes from healthy, SM-exposed, and COPD subjects were analyzed using two-dimensional gel electrophoresis followed by matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI TOF MS). Elastase activity was determined kinetically. The results showed that levels of S100 calcium-binding protein (CBP) A12, S100 CBP A8, glyceraldehyde-3-phosphate dehy-drogenase, superoxide dismutase, and protein disulfide isomerase proteins - as well as elastase activity - were significantly increased in PMN from 'diseased' hosts compared to in cells from healthy controls. In contrast, coactosin-like protein, RhoGDP dissociation inhibitor, and actin isoforms were significantly decreased in diseased subjects' PMN compared to PMN of healthy controls. Moreover, serpin B1 and coronin-1A were expressed only in PMN of the healthy subjects. Lastly, S100 CBP A9, endoplasmic reticulum (ER)-60 protease, and glutathione-S-transferase isoforms were differentially expressed in the cells from the SM-exposed and COPD subjects. These results show that serpin B1, an efficient inhibitor of neutrophil serine proteases, was not detectable, and elastase activity significantly increased in PMN from both SM-exposed and COPD patients. It seems that, apart from inflammation and oxidative stress, a protease:anti-protease imbalance exists within PMN of both COPD and SM-exposed patients.

Mechanistic insights of sulfur mustard-induced acute tracheal injury in rats.

Sulfur mustard (SM) is believed to be a major threat to civilian populations because of the persistent asymmetric threat by nonstate actors, such as terrorist groups, the ease of synthesis and handling, and the risk of theft from stockpiles. The purpose of this study was to establish mechanisms of acute tracheal injury in rats induced by SM using histopathologic, immunohistochemical, and biochemical parameters. Male rats (Sprague-Dawley) were anesthetized, intratracheally intubated, and exposed to 2 mg/kg of SM. Animals were euthanized 6-, 24-, 48-, and 72-hour postexposure, and intracavitary blood samples from the heart and tracheal tissues were collected. Exposure of rats to SM resulted in rapid tracheal injury, including tracheal epithelial cell shedding, focal ulceration, and abundant lymphocyte invasion of the submucosa. There was also evidence of a large number of apoptotic cells in the epithelium and submucosa, the serum levels of tumor necrosis factor α, interleukin 1ß (IL) 1ß, IL-6, and γ-glutamyl transferase peaked at 24 hours, and the serum levels of lactate dehydrogenase, glutathione peroxidase, and thiobarbituric acid reactive substance peaked at 6 hours. The SM exposure also resulted in a loss of the cellular membrane, leakage of cytoplasm, fuzzy mitochondrial cristae, medullary changes in ciliated and goblet cells, and the nuclear chromatin appeared marginated in basal cells and fibroblasts. The results in the propylene glycol group were the same as the control group. These data demonstrated the histologic changes, inflammatory reactions, apoptosis, oxidative stress, and DNA damage following SM (2 mg/kg)-induced acute tracheal injury; the severity of changes was time dependent.

Simultaneous determination of four sulfur mustard-DNA adducts in rabbit urine after dermal exposure by isotope-dilution liquid chromatography-tandem mass spectrometry.

Sulfur mustard (SM) is a classic vesicant agent, which has been greatly employed in several wars or military conflicts. The most lesion mechanism is its strong alkylation of DNAs in vivo. Until now there are four specific DNA adducts of SM identified for further retrospective detection, i.e., N(7)-(2-hydroxyethylthioethyl)-2'-guanine (N(7)-HETEG), bis(2-ethyl-N(7)-guanine)thioether (Bis-G), N(3)-(2-hydroxyethylthioethyl)-2'-adenine (N(3)-HETEA) and O(6)-(2-hydroxyethylthioethyl)-2'-guanine (O(6)-HETEG), respectively. Here, a novel and sensitive method of isotope-dilution ultrahigh performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) combining with solid phase extraction was reported for the simultaneous determination of four SM-DNA adducts. A lower limit of detection of 2-5ngL(-1), and a lower limit of quantitation of 5-10ngL(-1) were achieved, respectively, and the recoveries ranged from 87% to 116%. We applied this method in the determination of four SM-DNA adducts in rabbit urine after dermal exposure by SM in three dose levels (2, 5, 15mgkg(-1)), so as to investigate the related metabolic behavior in vivo. For the first time, in SM exposed rabbit urine, our results revealed the relative accumulation abundance of four SM-DNA adducts, i.e., 67.4% for N(7)-HETEG, 22.7% for Bis-G, 9.8% for N(3)-HETEA, 0.1% for O(6)-HETEG, and significant dose and time dependent responses of these SM-DNA adducts. The four adducts were detectable after 8h, afterwards, their contents continuously increased, achieved maximum in the first two or three days and then gradually decreased till the end of one month. Meanwhile, the amounts of SM-DNA adducts were positively correlated with the exposure doses.