Attenuation of half sulfur mustard gas-induced acute lung injury in rats

Oxidative Stress: An Intersection Between Radiation and Sulfur Mustard Lung Injury

Nuclear and chemical weapons of mass destruction share both a tragic and beneficial legacy in mankind's history and health. The horrific health effects of ionizing radiation and mustard gas exposures unleashed during disasters, wars, and conflicts have been harnessed to treat human health maladies. Both agents of destruction have been transformed into therapies to treat a wide range of cancers. The discovery of therapeutic uses of radiation and sulfur mustard was largely due to observations by clinicians treating victims of radiation and sulfur mustard gas exposures. Clinicians identified vulnerability of leukocytes to these agents and repurposed their use in the treatment of leukemias and lymphomas. Given the overlap in therapeutic modalities, it goes to reason that there may be common mechanisms to target as protective strategies against their damaging effects. This commentary will highlight oxidative stress as a common mechanism shared by both radiation and sulfur mustard gas exposures and discuss potential therapies targeting oxidative stress as medical countermeasures against the devastating lung diseases wrought by these agents.

Role of macrophage bioenergetics in N-acetylcysteine-mediated mitigation of lung injury and oxidative stress induced by nitrogen mustard

Nitrogen mustard (NM) is a toxic vesicant that causes acute injury to the respiratory tract. This is accompanied by an accumulation of activated macrophages in the lung and oxidative stress which have been implicated in tissue injury. In these studies, we analyzed the effects of N-acetylcysteine (NAC), an inhibitor of oxidative stress and inflammation on NM-induced lung injury, macrophage activation and bioenergetics. Treatment of rats with NAC (150 mg/kg, i.p., daily) beginning 30 min after administration of NM (0.125 mg/kg, i.t.) reduced histopathologic alterations in the lung including alveolar interstitial thickening, blood vessel hemorrhage, fibrin deposition, alveolar inflammation, and bronchiolization of alveolar walls within 3 d of exposure; damage to the alveolar-epithelial barrier, measured by bronchoalveolar lavage fluid protein and cells, was also reduced by NAC, along with oxidative stress as measured by heme oxygenase (HO)-1 and Ym-1 expression in the lung. Treatment of rats with NAC attenuated the accumulation of macrophages in the lung expressing proinflammatory genes including Ptgs2, Nos2, Il-6 and Il-12; macrophages expressing inducible nitric oxide synthase (iNOS), cyclooxygenase (COX)-2 and tumor necrosis factor (TNF)α protein were also reduced in histologic sections. Conversely, NAC had no effect on macrophages expressing the anti-inflammatory proteins arginase-1 or mannose receptor, or on NM-induced increases in matrix metalloproteinase (MMP)-9 or proliferating cell nuclear antigen (PCNA), markers of tissue repair. Following NM exposure, lung macrophage basal and maximal glycolytic activity increased, while basal respiration decreased indicating greater reliance on glycolysis to generate ATP. NAC increased both glycolysis and oxidative phosphorylation. Additionally, in macrophages from both control and NM treated animals, NAC treatment resulted in increased S-nitrosylation of ATP synthase, protecting the enzyme from oxidative damage. Taken together, these data suggest that alterations in NM-induced macrophage activation and bioenergetics contribute to the efficacy of NAC in mitigating lung injury.

Mesna Improves Outcomes of Sulfur Mustard Inhalation Toxicity in an Acute Rat Model

Inhalation of high levels of sulfur mustard (SM), a potent vesicating and alkylating agent used in chemical warfare, results in acutely lethal pulmonary damage. Sodium 2-mercaptoethane sulfonate (mesna) is an organosulfur compound that is currently Food and Drug Administration (FDA)-approved for decreasing the toxicity of mustard-derived chemotherapeutic alkylating agents like ifosfamide and cyclophosphamide. The nucleophilic thiol of mesna is a suitable reactant for the neutralization of the electrophilic group of toxic mustard intermediates. In a rat model of SM inhalation, treatment with mesna (three doses: 300 mg/kg intraperitoneally 20 minutes, 4 hours, and 8 hours postexposure) afforded 74% survival at 48 hours, compared with 0% survival at less than 17 hours in the untreated and vehicle-treated control groups. Protection from cardiopulmonary failure by mesna was demonstrated by improved peripheral oxygen saturation and increased heart rate through 48 hours. Additionally, mesna normalized arterial pH and pACO2 Airway fibrin cast formation was decreased by more than 66% in the mesna-treated group at 9 hour after exposure compared with the vehicle group. Finally, analysis of mixtures of a mustard agent and mesna by a 5,5'-dithiobis(2-nitrobenzoic acid) assay and high performance liquid chromatography tandem mass spectrometry demonstrate a direct reaction between the compounds. This study provides evidence that mesna is an efficacious, inexpensive, FDA-approved candidate antidote for SM exposure. SIGNIFICANCE STATEMENT: Despite the use of sulfur mustard (SM) as a chemical weapon for over 100 years, an ideal drug candidate for treatment after real-world exposure situations has not yet been identified. Utilizing a uniformly lethal animal model, the results of the present study demonstrate that sodium 2-mercaptoethane sulfonate is a promising candidate for repurposing as an antidote, decreasing airway obstruction and improving pulmonary gas exchange, tissue oxygen delivery, and survival following high level SM inhalation exposure, and warrants further consideration.

Acteoside attenuates acute lung injury following administration of cobra venom factor to mice

Background

Acteoside, a water-soluble active constituent of diverse valuable medicinal vegetation, has shown strong anti-inflammatory property. However, studies on the anti-inflammatory property of acteoside in complement-induced acute lung injury (ALI) are limited. Therefore, this study aims to evaluate the anti-inflammatory activity of acteoside in cobra venom factor (CVF)-stimulated human microvascular endothelial cells (HMEC) and in ALI mice model.

Methods

In this study, we investigated the effects of acteoside (20, 10, and 5 μg/mL) in vitro in CVF induced HMECs and the activity of acteoside (100, 50, and 20 mg/kg/day bodyweight) in vivo in CVF induced ALI mice. Each eight male mice were orally administered acteoside or the positive drug PDTC (100 mg/kg/day) for 7 days before CVF (35 μg/kg) injection. After injection for 1 h, the pharmacological effects of acteoside were investigated by spectrophotometry, pathological examination, enzyme-linked immunosorbent assay, and immunohistochemistry.

Results

In vitro, acteoside (20, 10, and 5 μg/mL) reduced the protein expression of adhesion molecules and pro-inflammatory cytokines and transcriptional activity of NF-κB (P < 0.01). In vivo studies showed that acteoside dose-dependently alleviated lung histopathologic lesion, inhibited the production of the protein content of BALF, leukocyte cell number, lung MPO activity, and expression levels of IL-6, TNF-α, and ICAM-1, and suppressed the C5b-9 deposition and NF-κB activation in CVF-induced acute lung inflammation in mice (P < 0.05, 0.01).

Conclusion

This study demonstrates that acteoside exerts strong anti-inflammatory activities in the CVF-induced acute lung inflammation model and suggests that acteoside is a potential therapeutic agent for complement-related inflammatory diseases.

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.

Vitamin D3 protects against nitrogen mustard-induced apoptosis of the bronchial epithelial cells via activating the VDR/Nrf2/Sirt3 pathway

Respiratory system injury is the main cause of mortality for nitrogen mustard (NM)-induced damage. Previous studies indicate that reactive oxygen species (ROS) participates in NM-mediated respiratory injuries, but the detailed mechanism is not quite clear. Human bronchial epithelial cell lines 16HBE and BEAS-2B were treated with HN2, a type of NM. In detail, it was shown that HN2 treatment induced impaired cell viability, excessive mitochondrial ROS production and enhanced cellular apoptosis in bronchial epithelial cells. Moreover, impaired Sirt3/SOD2 axis was observed upon HN2 treatment, with decreased Sirt3 and increased acetylated SOD2 expression levels. Sirt3 overexpression partially ameliorated HN2-induced cell injury. Meanwhile, vitamin D3 treatment partially attenuated HN2-induced apoptosis and improved the mitochondrial functions upon HN2 intervention. In addition, HN2 exposure decreased VDR expression, thus inhibiting the Nrf2 phosphorylation and Sirt3 activation. Inhibition of Nrf2 or Sirt3 could decrease the protective effects of vitamin D3 and enhance mitochondrial ROS production via modulating mitochondrial redox balance. In conclusion, impaired VDR/Nrf2/Sirt3 axis contributed to NM-induced apoptosis, while vitamin D3 supplementation provides protective effects via the activation of VDR and the improvement of mitochondrial functions. This study provides novel mechanism and strategy for NM exposure-induced pulmonary injuries.

Deciphering the role of microRNAs in mustard gas-induced toxicity

Mustard gas (sulfur mustard, SM), a highly vesicating chemical warfare agent, was first deployed in warfare in 1917 and recently during the Iraq-Iran war (1980s) and Syrian conflicts (2000s); however, the threat of exposure from stockpiles and old artillery shells still looms large. Whereas research has been long ongoing on SM-induced toxicity, delineating the precise molecular pathways is still an ongoing area of investigation; thus, it is important to attempt novel approaches to decipher these mechanisms and develop a detailed network of pathways associated with SM-induced toxicity. One such avenue is exploring the role of microRNAs (miRNAs) in SM-induced toxicity. Recent research on the regulatory role of miRNAs provides important results to fill in the gaps in SM toxicity-associated mechanisms. In addition, differentially expressed miRNAs can also be used as diagnostic markers to determine the extent of toxicity in exposed individuals. Thus, in our review, we have summarized the studies conducted so far in cellular and animal models, including human subjects, on the expression profiles and roles of miRNAs in SM- and/or SM analog-induced toxicity. Further detailed research in this area will guide us in devising preventive strategies, diagnostic tools, and therapeutic interventions against SM-induced toxicity.

N-Acetylcysteine as a treatment for sulphur mustard poisoning

In the long and intensive search for effective treatments to counteract the toxicity of the chemical warfare (CW) agent sulphur mustard (H; bis(2-chloroethyl) sulphide), the most auspicious and consistent results have been obtained with the drug N-acetylcysteine (NAC), particularly with respect to its therapeutic use against the effects of inhaled H. It is a synthetic cysteine derivative that has been used in a wide variety of clinical applications for decades and a wealth of information exists on its safety and protective properties against a broad range of toxicants and disease states. Its primary mechanism of action is as a pro-drug for the synthesis of the antioxidant glutathione (GSH), particularly in those circumstances where oxidative stress has exhausted intracellular GSH stores. It impacts a number of pathways either directly or through its GSH-related antioxidant and anti-inflammatory properties, which make it a prime candidate as a potential treatment for the wide range of deleterious cellular effects that H is acknowledged to cause in exposed individuals. This report reviews the available literature on the protection afforded by NAC against the toxicity of H in a variety of model systems, including its efficacy in treating the long-term chronic lung effects of H that have been demonstrated in Iranian veterans exposed during the Iran-Iraq War (1980-1988). Although there is overwhelming evidence supporting this drug as a potential medical countermeasure against this CW agent, there is a requirement for carefully controlled clinical trials to determine the safety, efficacy and optimal NAC dosage regimens for the treatment of inhaled H.

Chemical warfare agent research in precision-cut tissue slices-a useful alternative approach

The use of chemical warfare agents (CWAs) in military conflicts and against civilians is a recurrent problem. Despite ongoing CWA research using in vitro or in vivo models, progress to elucidate mechanisms of toxicity and to develop effective therapies, decontamination procedures, and general countermeasures is still limited. Novel scientific approaches to address these questions are needed to expand perspectives on existing knowledge and gain new insights. To achieve this, the use of ex vivo techniques like precision-cut tissue slices (PCTSs) can be a valuable approach. Existing studies employing this economical and relatively easy to implement method show model suitability and comparability with the use of in vitro and in vivo models. In this article, we review research on CWAs in PCTSs to illustrate the advantages of the approach and to promote future applications.

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.

MicroRNA-mediated inflammation and coagulation effects in rats exposed to an inhaled analog of sulfur mustard

Exposure of rats to 2-chloroethyl ethyl sulfide (CEES), an analog of sulfur mustard, can cause acute lung injury (ALI), resulting in increased inflammation and coagulation and altered levels of plasma microRNAs (miRNAs). Rats were exposed to aerosolized CEES and euthanized 12 h later for collection of tissue and plasma. Profiling of miRNAs in plasma, using a TaqMan-based RT-PCR array, revealed 14 differentially expressed miRNAs. Target gene prediction and pathway analysis revealed miRNA-mediated regulation of organismal injury, inflammation, and respiratory diseases. miR-140-5p, a marker of ALI, was downregulated in the plasma, lung, liver, and kidney of CEES-exposed rats, with a concomitant increase in the expression of the inflammation markers IL-6 and IL-1α and the coagulation marker tissue factor (F3). Exposure of rat airway epithelial cells (RL-65) to CEES (0.5 mM) caused cell death and a decrease in miR-140-5p both in cells and media supernatant. This was accompanied by an increase in cellular mRNA levels of IL-6, IL-1α, and F3, as well as FGF9 and EGR2, putative targets of miR-140. Knockdown of miR-140 by specific oligos in RL-65 cells mimicked the in vivo CEES-mediated effects, leading to significantly increased mRNA levels of IL-6, IL-1α, F3, FGF9, and EGR2. Our study identifies miR-140-5p as a mediator of CEES-induced ALI, which could potentially be targeted for therapy.

Pulmonary protective efficacy of S-2[2-aminoethylamino] ethyl phenyl sulphide (DRDE-07) and its analogues against sulfur mustard induced toxicity in mice

Our previous study showed that percutaneous sulfur mustard (SM) exposure induced pulmonary toxicity, which was attenuated by DRDE-07 (S-2[2-aminoethylamino] ethyl phenyl sulphide) pretreatment. The present study aimed to evaluate the protective efficacy of DRDE-07 and its analogues viz., DRDE-30 (S-2(2-aminoethyl amino)ethyl propyl sulphide) and DRDE-35 (S-2(2-aminoethyl amino)ethyl butyl sulphide) against SM. Thirty minutes before percutaneous SM (0.8 LD₅₀) exposure, female Swiss mice were orally gavaged with DRDE-07 and its analogues(0.2 LD₅₀). Animals were sacrificed on day 3 and 7, BAL fluid (BALF) and lung tissue were collected for biochemical, histopathological studies. As results, DRDE-07 and its analogues were beneficial in reducing the number of BALF inflammatory cells, protein level, lactate dehydrogenase (LDH) activity, myeloperoxidase (MPO) and β-glucuronidase activity, while content of BALF and lung reduced glutathione level (GSH) were significantly protected. The pretreatment of DRDE-07 and its analogues inhibited the recruitment of inflammatory cells into the lung. The beneficial effects of DRDE-07 and its analogues were attributed to their antioxidant and anti-inflammatory activity. Among the analogues, DRDE-30 exhibited significant beneficial effects as compared to the other two compounds. These analogues may be considered as prototype candidate molecules as there is no effective antidote for SM toxicity.

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.

Extracellular nucleic acid scavenging rescues rats from sulfur mustard analog-induced lung injury and mortality

Sulfur mustard (SM) is a highly toxic war chemical that causes significant morbidity and mortality and lacks any effective therapy. Rats exposed to aerosolized CEES (2-chloroethyl ethyl sulfide; 10% in ethanol), an analog of SM, developed acute respiratory distress syndrome (ARDS), which is characterized by increased inflammation, hypoxemia and impaired gas exchange. We observed elevated levels of extracellular nucleic acids (eNA) in the bronchoalveolar lavage fluid (BALF) of CEES-exposed animals. eNA can induce inflammation, coagulation and barrier dysfunction. Treatment with hexadimethrine bromide (HDMBr; 10 mg/kg), an eNA neutralizing agent, 2 h post-exposure, reduced lung injury, inhibited disruption of alveolar-capillary barrier, improved blood oxygenation (PaO₂/FiO₂ ratio), thus reversing ARDS symptoms. HDMBr treatment also reduced lung inflammation in the CEES-exposed animals by decreasing IL-6, IL-1A, CXCL-1 and CCL-2 mRNA levels in lung tissues and HMGB1 protein in BALF. Furthermore, HDMBr treatment also reduced levels of lung tissue factor and plasminogen activator inhibitor-1 indicating reduction in clot formation and increased fibrinolysis. Fibrin was reduced in BALF of the HDMBr-treated animals. This was further confirmed by histology that revealed diminished airway fibrin, epithelial sloughing and hyaline membrane in the lungs of HDMBr-treated animals. HDMBr completely rescued the CEES-associated mortality 12 h post-exposure when the survival rate in CEES-only group was just 50%. Experimental eNA treatment of cells caused increased inflammation that was reversed by HDMBr. These results demonstrate a role of eNA in the pathogenesis of CEES/SM-induced injury and that its neutralization can serve as a potential therapeutic approach in treating SM toxicity.

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.

Polyethylene Glycol-Poly-Lactide-co-Glycolide Block Copolymer-Based Nanoparticles as a Potential Tool for Off-Label Use of N-Acetylcysteine in the Treatment of Diastrophic Dysplasia

Potential off-label therapeutic role of N-acetylcysteine (N-Ac) was recently demonstrated in the treatment of diastrophic dysplasia (DTD) using mutant mice; its main drawback is the rapid clearance from blood due to the liver metabolism. Our goal was to investigate the potential of polyethylene glycol polylactide-co-glycolide block copolymer (PLGA-PEG)-based nanoparticles (NPs) in order to improve in vivo biodistribution performances and N-Ac pharmacokinetic profile after subcutaneous administration in mice. Results suggest that N-Ac can be effectively loaded into NPs (about 99 μg/mg NPs) using a suitably optimized nanoprecipitation method. Thanks to the good physical characteristics (mean diameter <100 nm, zeta potential about -8 mV) NPs can reach skeletal tissue in particular femoral head and proximal tibia epiphysis at the sixth hour after injection, remaining in the tissues till 24 h. Furthermore, pharmacokinetic study revealed a sustained N-Ac concentration in plasma with a peak concentration of 2.48 ± 1.72 μM at the 24th hour after injection. Overall, results highlight the actual interest of N-Ac-loaded PLGA-PEG NPs as useful platform for N-Ac parenteral administration.

Attenuation of Multiple Organ Damage by Continuous Low-Dose Solvent-Free Infusions of Resveratrol after Severe Hemorrhagic Shock in Rats

Therapeutic effects of continuous intravenous infusions of solvent-free low doses of resveratrol on organ injury and systemic consequences resulting from severe hemorrhagic shock in rats were studied. Hemorrhagic shock was induced by withdrawing arterial blood until a mean arterial blood pressure (MAP) of 25-30 mmHg was reached. Following a shock phase of 60 min, rats were resuscitated with the withdrawn blood plus lactated Ringer's. Resveratrol (20 or 60 μg/kg × h) was continuously infused intravenously starting with the resuscitation phase (30 min) and continued until the end of the experiment (total treatment time 180 min). Animals of the shock control group received 0.9% NaCl solution. After the observation phase (150 min), rats were sacrificed. Resveratrol significantly stabilized the MAP and peripheral oxygen saturation after hemorrhagic shock, decreased the macroscopic injury of the small intestine, significantly attenuated the shock-induced increase in tissue myeloperoxidase activity in the small intestine, liver, kidney and lung, and diminished tissue hemorrhages (particularly in the small intestine and liver) as well as the rate of hemolysis. Already very low doses of resveratrol, continuously infused during resuscitation after severe hemorrhagic shock, can significantly improve impaired systemic parameters and attenuate multiple organ damage in rats.

Mustard vesicant-induced lung injury: Advances in therapy

Most mortality and morbidity following exposure to vesicants such as sulfur mustard is due to pulmonary toxicity. Acute injury is characterized by epithelial detachment and necrosis in the pharynx, trachea and bronchioles, while long-term consequences include fibrosis and, in some instances, cancer. Current therapies to treat mustard poisoning are primarily palliative and do not target underlying pathophysiologic mechanisms. New knowledge about vesicant-induced pulmonary disease pathogenesis has led to the identification of potentially efficacious strategies to reduce injury by targeting inflammatory cells and mediators including reactive oxygen and nitrogen species, proteases and proinflammatory/cytotoxic cytokines. Therapeutics under investigation include corticosteroids, N-acetyl cysteine, which has both mucolytic and antioxidant properties, inducible nitric oxide synthase inhibitors, liposomes containing superoxide dismutase, catalase, and/or tocopherols, protease inhibitors, and cytokine antagonists such as anti-tumor necrosis factor (TNF)-α antibody and pentoxifylline. Antifibrotic and fibrinolytic treatments may also prove beneficial in ameliorating airway obstruction and lung remodeling. More speculative approaches include inhibitors of transient receptor potential channels, which regulate pulmonary epithelial cell membrane permeability, non-coding RNAs and mesenchymal stem cells. As mustards represent high priority chemical threat agents, identification of effective therapeutics for mitigating toxicity is highly significant.

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.

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 1β (IL) 1β, 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.

Effects of CEES and LPS synergistically stimulate oxidative stress inactivates OGG1 signaling in macrophage cells

2-chloroethyl ethyl sulphide (CEES), a monofunctional analogue of sulfur mustard, is a strong vesicant and an alkylating chemical warfare agent. We studied the molecular mechanism of oxidative stress triggered signaling cascades in murine macrophages exposed to CEES with lipopolysaccharide (LPS). Exposure of CEES with specific dose of LPS stimulates oxidative stress caused increasing level of intracellular ROS and RNS, decreased antioxidant enzymes, increasing bimolecular damage, reduced cell viability, and cell cycle arrest. Synergistic exposure of CEES and LPS provoked significant increase in phosphorylation of MAPKs, Akt, tuberin, that down regulate OGG1 expression and 8-OHdG accumulations. Treatment with Akt and ERK1/2 inhibitors, the cells with constitutively active inhibiting activity of Akt and ERK1/2MAPK significant reduce CEES and LPS challenge tuberin but not the OGG1. In addition, the N-acetylcysteine inhibited ROS/RNS generation, elevation of antioxidants level, expression of ERK1/2, Akt, tuberin phosphorylation, resulted in deceased 8-OHdG accumulation and upregulation of OGG1 protein expression suggesting no involvement of Akt and ERK1/2MAPK pathways after CEES and LPS challenge. Collectively, our results indicate that exposure of CEES and LPS induces oxidative stress and the activation of tuberin, and 8-OHdG accumulation via upstream signaling pathways including Akt and ERK1/2MAPK pathway in macrophages but not the down regulation of OGG1.

Role of nicotinamide adenine dinucleotide phosphate oxidase in mediating vesicant-induced interleukin-6 secretion in human airway epithelial cells

Aerosolized exposure to the chemical warfare vesicant sulfur mustard and its analog nitrogen mustard (HN2) is known to induce airway lesions associated with secretion of proinflammatory cytokines such as IL-6. We have shown recently that HN2 challenge induced IL-6 secretion in human airway epithelial cells, a process mediated via epidermal growth factor receptor (EGFR) signaling. In this study, we evaluated the role of redox signaling in regulating HN2-induced, EGFR-mediated IL-6 secretions in primary cultured normal human bronchial epithelial cells (NHBECs) in the air-liquid interface. HN2-induced EGFR phosphorylation and IL-6 secretion in NHBECs were inhibited by the antioxidant N-acetyl-L-cysteine (NAC) and by the flavoprotein inhibitor diphenyleneiodonium chloride (DPI). These observations suggested that the inflammatory response in NHBECs after HN2 challenge was mediated via oxidative stress. HN2 exposure induced increased reactive oxygen species (ROS) formation and nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activity in NHBECs, findings that were inhibited by NAC and DPI treatment. Among NADPH oxidase isoforms, mRNA expression of dual oxidase (DUOX)1 and DUOX2 were up-regulated by HN2. Furthermore, knockdown of DUOX1 or DUOX2 by short hairpin RNA resulted in inhibition of ROS generation, EGFR pathway activation, and IL-6 secretion in NHBECs. These results provide evidence that redox signaling plays a pivotal role in the HN2-induced airway inflammation and underscore the importance of DUOX1 and DUOX2 in vesicant-induced IL-6 secretion in human airway epithelial cells.

Pentoxifylline attenuates nitrogen mustard-induced acute lung injury, oxidative stress and inflammation

Nitrogen mustard (NM) is a toxic alkylating agent that causes damage to the respiratory tract. Evidence suggests that macrophages and inflammatory mediators including tumor necrosis factor (TNF)α contribute to pulmonary injury. Pentoxifylline is a TNFα inhibitor known to suppress inflammation. In these studies, we analyzed the ability of pentoxifylline to mitigate NM-induced lung injury and inflammation. Exposure of male Wistar rats (150-174 g; 8-10 weeks) to NM (0.125 mg/kg, i.t.) resulted in severe histopathological changes in the lung within 3d of exposure, along with increases in bronchoalveolar lavage (BAL) cell number and protein, indicating inflammation and alveolar-epithelial barrier dysfunction. This was associated with increases in oxidative stress proteins including lipocalin (Lcn)2 and heme oxygenase (HO)-1 in the lung, along with pro-inflammatory/cytotoxic (COX-2(+) and MMP-9(+)), and anti-inflammatory/wound repair (CD163+ and Gal-3(+)) macrophages. Treatment of rats with pentoxifylline (46.7 mg/kg, i.p.) daily for 3d beginning 15 min after NM significantly reduced NM-induced lung injury, inflammation, and oxidative stress, as measured histologically and by decreases in BAL cell and protein content, and levels of HO-1 and Lcn2. Macrophages expressing COX-2 and MMP-9 also decreased after pentoxifylline, while CD163+ and Gal-3(+) macrophages increased. This was correlated with persistent upregulation of markers of wound repair including pro-surfactant protein-C and proliferating nuclear cell antigen by Type II cells. NM-induced lung injury and inflammation were associated with alterations in the elastic properties of the lung, however these were largely unaltered by pentoxifylline. These data suggest that pentoxifylline may be useful in treating acute lung injury, inflammation and oxidative stress induced by vesicants.

Mustard Gas Inhalation Injury

Mustard gas (sulfur mustard [SM], bis-[2-chloroethyl] sulfide) is a vesicating chemical warfare agent and a potential chemical terrorism agent. Exposure of SM causes debilitating skin blisters (vesication) and injury to the eyes and the respiratory tract; of these, the respiratory injury, if severe, may even be fatal. Therefore, developing an effective therapeutic strategy to protect against SM-induced respiratory injury is an urgent priority of not only the US military but also the civilian antiterrorism agencies, for example, the Homeland Security. Toward developing a respiratory medical countermeasure for SM, four different classes of therapeutic compounds have been evaluated in the past: anti-inflammatory compounds, antioxidants, protease inhibitors and antiapoptotic compounds. This review examines all of these different options; however, it suggests that preventing cell death by inhibiting apoptosis seems to be a compelling strategy but possibly dependent on adjunct therapies using the other drugs, that is, anti-inflammatory, antioxidant, and protease inhibitor compounds.

Tissue factor pathway inhibitor prevents airway obstruction, respiratory failure and death due to sulfur mustard analog inhalation

Sulfur mustard (SM) inhalation causes airway injury, with enhanced vascular permeability, coagulation, and airway obstruction. The objective of this study was to determine whether recombinant tissue factor pathway inhibitor (TFPI) could inhibit this pathogenic sequence.

METHODS

Rats were exposed to the SM analog 2-chloroethyl ethyl sulfide (CEES) via nose-only aerosol inhalation. One hour later, TFPI (1.5mg/kg) in vehicle, or vehicle alone, was instilled into the trachea. Arterial O2 saturation was monitored using pulse oximetry. Twelve hours after exposure, animals were euthanized and bronchoalveolar lavage fluid (BALF) and plasma were analyzed for prothrombin, thrombin-antithrombin complex (TAT), active plasminogen activator inhibitor-1 (PAI-1) levels, and fluid fibrinolytic capacity. Lung steady-state PAI-1 mRNA was measured by RT-PCR analysis. Airway-capillary leak was estimated by BALF protein and IgM, and by pleural fluid measurement. In additional animals, airway cast formation was assessed by microdissection and immunohistochemical detection of airway fibrin.

RESULTS

Airway obstruction in the form of fibrin-containing casts was evident in central conducting airways of rats receiving CEES. TFPI decreased cast formation, and limited severe hypoxemia. Findings of reduced prothrombin consumption, and lower TAT complexes in BALF, demonstrated that TFPI acted to limit thrombin activation in airways. TFPI, however, did not appreciably affect CEES-induced airway protein leak, PAI-1 mRNA induction, or inhibition of the fibrinolytic activity present in airway surface liquid.

CONCLUSIONS

Intratracheal administration of TFPI limits airway obstruction, improves gas exchange, and prevents mortality in rats with sulfur mustard-analog-induced acute lung injury.

Therapeutic effect of liposomal-N-acetylcysteine against acetaminophen-induced hepatotoxicity

BACKGROUND

Acetaminophen (APAP) is an antipyretic analgesic drug that when taken in overdose causes depletion of glutathione (GSH) and hepatotoxicity. N-acetylcysteine (NAC) is the antidote of choice for the treatment of APAP toxicity; however, due to its short-half-life repeated dosing of NAC is required.

PURPOSE

To determine whether a NAC-loaded liposomal formulation (Lipo-NAC) is more effective than the conventional NAC in protecting against acute APAP-induced hepatotoxicity.

METHODS

Male Sprague-Dawley rats were challenged with an intragastric dose of APAP (850 mg/kg b.wt.); 4 h later, animals were administered saline, NAC, Lipo-NAC or empty liposomes and sacrificed 24 h post-APAP treatment.

RESULTS

APAP administration resulted in hepatic injury as evidenced by increases in plasma bilirubin, alanine (AST) and aspartate (ALT) aminotransferase levels and tissue levels of lipid peroxidation and myeloperoxidase as well as decreases in hepatic levels of reduced GSH, GSH peroxidase and GSH reductase. Treatment of animals with Lipo-NAC was significantly more effective than free NAC in reducing APAP-induced hepatotoxicity. Histological evaluation showed that APAP caused periacinar hepatocellular apoptosis and/or necrosis of hepatocytes around the terminal hepatic venules which was reduced by NAC treatment, the degree of reduction being greater for Lipo-NAC.

CONCLUSION

These data suggest that administration of Lipo-NAC ameliorated the APAP-induced hepatotoxicity.

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

CONTEXT

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSION

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

Attenuation of acute nitrogen mustard-induced lung injury, inflammation and fibrogenesis by a nitric oxide synthase inhibitor

Nitrogen mustard (NM) is a toxic vesicant known to cause damage to the respiratory tract. Injury is associated with increased expression of inducible nitric oxide synthase (iNOS). In these studies we analyzed the effects of transient inhibition of iNOS using aminoguanidine (AG) on NM-induced pulmonary toxicity. Rats were treated intratracheally with 0.125 mg/kg NM or control. Bronchoalveolar lavage fluid (BAL) and lung tissue were collected 1 d-28 d later and lung injury, oxidative stress and fibrosis assessed. NM exposure resulted in progressive histopathological changes in the lung including multifocal lesions, perivascular and peribronchial edema, inflammatory cell accumulation, alveolar fibrin deposition, bronchiolization of alveolar septal walls, and fibrosis. This was correlated with trichrome staining and expression of proliferating cell nuclear antigen (PCNA). Expression of heme oxygenase (HO)-1 and manganese superoxide dismutase (Mn-SOD) was also increased in the lung following NM exposure, along with levels of protein and inflammatory cells in BAL, consistent with oxidative stress and alveolar-epithelial injury. Both classically activated proinflammatory (iNOS⁺ and cyclooxygenase-2⁺) and alternatively activated profibrotic (YM-1⁺ and galectin-3⁺) macrophages appeared in the lung following NM administration; this was evident within 1d, and persisted for 28 d. AG administration (50 mg/kg, 2×/day, 1d-3 d) abrogated NM-induced injury, oxidative stress and inflammation at 1d and 3d post exposure, with no effects at 7 d or 28 d. These findings indicate that nitric oxide generated via iNOS contributes to acute NM-induced lung toxicity, however, transient inhibition of iNOS is not sufficient to protect against pulmonary fibrosis.

Airway tissue factor-dependent coagulation activity in response to sulfur mustard analog 2-chloroethyl ethyl sulfide

Acute lung injury is a principal cause of morbidity and mortality in response to mustard gas (SM) inhalation. Obstructive, fibrin-containing airway casts have recently been reported in a rat inhalation model employing the SM analog 2-chloroethyl ethyl sulfide (CEES). The present study was designed to identify the mechanism(s) causing activation of the coagulation cascade after CEES-induced airway injury. Here we report that CEES inhalation elevates tissue factor (TF) activity and numbers of detached epithelial cells present in lavage fluid (BALF) from rats after exposure (18 h). In vitro studies using 16HBE cells, or with rat BALF, indicated that detached epithelial cells could convert factor X (FX) to the active form FXa when incubated with factor VII and could elicit rapid clotting of plasma. In addition, immunocytochemical analysis demonstrated elevated cell surface (TF) expression on CEES-exposed 16HBE cells as a function of time. However, total cell TF expression did not increase. Since membrane surfaces bearing TF are important determinants of clot initiation, anticoagulants directed against these entities were tested for ability to limit plasma clotting or FX activation capacity of BALF or culture media. Addition of tifacogin, a TF pathway inhibitor, effectively blocked either activity, demonstrating that the procoagulant actions of CEES were TF pathway dependent. Lactadherin, a protein capable of competing with clotting factors for phospholipid-binding sites, was partially effective in limiting these procoagulant actions. These findings indicate that TF pathway inhibition could be an effective strategy to prevent airway obstruction after SM or CEES inhalation.

Estimation of the action of three different mechlorethamine doses on biochemical parameters during experimentally induced pleuritis in rats

Nitrogranulogen (NTG) may modify the character of inflammatory reactions. These modifications are a result of cytotoxic and mutagenic effects. NTG has high affinity to DNA and causes disorders in the synthesis of acute phase proteins (e.g., haptoglobin, transferrin, fibrinogen, and complement protein C3). Our previous studies have shown that small doses of NTG can enhance immunological defense reactions in the organism. The aim of the current studies was to determine how different NTG doses cause changes in the values of biochemical parameters in pleuritis-induced rats. The animals were randomized into five groups: Group I - control group; Group II - IP (induced pleuritis) group; Group III - NTG5 group; Group IV - NTG50 group; Group V - NTG600 group. Blood was collected from all groups of animals at 24, 48, and 72 h after the initiation of the carrageenin-induced inflammatory reaction. These investigations revealed that a dose of 5 μg NTG/kg b.w. (body weight) can change the character of the inflammation. Our studies also show that a dose of 600 μg NTG/kg b.w. causes a rapid decrease in the level of C3 at the 72 h of the experiment (after 3 applications every 24 h), which indicates a cytotoxic action of such a large NTG dose. NTG used at doses of 50 and 600 μg/kg b.w. causes the opposite metabolism of albumins and other serum proteins. Our studies show that the different doses of NTG have distinct effects on the inflammatory reaction.

The effect of Nigella sativa alone, and in combination with dexamethasone, on tracheal muscle responsiveness and lung inflammation in sulfur mustard exposed guinea pigs

ETHNOMEDICAL RELEVANCE: The anti-inflammatory activity of both systemic and local administrations of essential oil from Nigella sativa L. has been shown.

AIM OF THE STUDY

Therefore, the effect of Nigella sativa on tracheal responsiveness (TR) and lung inflammation of sulfur mustard (SM) exposed guinea pigs was examined.

MATERIALS AND METHODS

Guinea pigs were exposed to diluent solution (control group), inhaled SM (SME group), SME treated with Nigella sativa (SME+N), SME treated with dexamethasone (SME+D) and SME treated with both drugs (SME+N+D), (n=7 for each group). TR to methacholine, total white blood cell (WBC) and differential WBC count of lung lavage, and serum cytokines were measured 14 days post-exposure.

RESULTS

The values of TR, eosinophil, monocyte, lymphocyte, interleukine-4 (IL-4) and interferon gamma (IFN-γ) of SME group were significantly higher than those of controls (p<0.05 to p<0.001). The TR in SME+N, SME+D and SME+N+D was significantly lower compared to that of SME group (p<0.01 for all cases). The percentage of eosinophil in SME+D, and the percentage of monocyte in SME+N+D (p<0.05 to p<0.01) were significantly lower than those in SME group. The neutrophil number was decreased in SME+N and SME+N+D groups compared to SME animals (p<0.05 to p<0.01). IL-4 levels in serum of SME+N (p<0.01), SME+D (p<0.05), SME+N+D (p<0.01) and IFN-γ in SME+N (p<0.05) were greater than those in SME animals.

CONCLUSIONS

These results showed a preventive effect of Nigella sativa on TR and lung inflammation of SM exposed guinea pigs.

Liposomal Antioxidants for Protection against Oxidant-Induced Damage

Reactive oxygen species (ROS), including superoxide anion, hydrogen peroxide, and hydroxyl radical, can be formed as normal products of aerobic metabolism and can be produced at elevated rates under pathophysiological conditions. Overproduction and/or insufficient removal of ROS result in significant damage to cell structure and functions. In vitro studies showed that antioxidants, when applied directly and at relatively high concentrations to cellular systems, are effective in conferring protection against the damaging actions of ROS, but results from animal and human studies showed that several antioxidants provide only modest benefit and even possible harm. Antioxidants have yet to be rendered into reliable and safe therapies because of their poor solubility, inability to cross membrane barriers, extensive first-pass metabolism, and rapid clearance from cells. There is considerable interest towards the development of drug-delivery systems that would result in the selective delivery of antioxidants to tissues in sufficient concentrations to ameliorate oxidant-induced tissue injuries. Liposomes are biocompatible, biodegradable, and nontoxic artificial phospholipid vesicles that offer the possibility of carrying hydrophilic, hydrophobic, and amphiphilic molecules. This paper focus on the use of liposomes for the delivery of antioxidants in the prevention or treatment of pathological conditions related to oxidative stress.

Role of reactive oxygen and nitrogen species in olfactory epithelial injury by the sulfur mustard analogue 2-chloroethyl ethyl sulfide

The inhalation of sulfur mustard (SM) causes substantial deposition in the nasal region. However, specific injury has not been characterized. 2-chloroethyl ethyl sulfide (CEES) is an SM analogue used to model injury and screen potential therapeutics. After the inhalation of CEES, damage to the olfactory epithelium (OE) was extensive. Terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling-positive cells were present by 4 hours, and maximal at 18-72 hours. Cleaved caspase 3 immunohistochemistry (IHC) was maximal at 18 hours after the inhalation of 5% CEES. Olfactory marker protein (OMP)-positive olfactory neurons were markedly decreased at 18 hours. IHC-positive cells for 3-nitrotyrosine (3-NT) within epithelium were elevated by 8 hours, waning by 18 hours, and absent by 72 hours. AEOL 10150, a catalytic manganoporphyrin antioxidant, administered both subcutaneously (5 mg/kg) and intranasally (50 μM, "combined treatment"), decreased OE injury. CEES-induced increases in markers of cell death were decreased by combined treatment involving AEOL 10150. CEES-induced changes in OMP and 3-NT immunostaining were markedly improved by combined treatment involving AEOL 10150. The selective inducible nitric oxide synthase inhibitor 1400W (5 mg/kg, subcutaneous), administered 1 hour after inhalation and thereafter every 4 hours (five doses), also reduced OE damage with improved OMP and 3-NT staining. Taken together, these data indicate that reactive oxygen and nitrogen species are important mediators in CEES-induced nasal injury.

Protective effect of liposome-encapsulated glutathione in a human epidermal model exposed to a mustard gas analog

Sulfur mustard or mustard gas (HD) and its monofunctional analog, 2-chloroethyl ethyl sulfide (CEES), or "half-mustard gas," are alkylating agents that induce DNA damage, oxidative stress, and inflammation. HD/CEES are rapidly absorbed in the skin causing extensive injury. We hypothesize that antioxidant liposomes that deliver both water-soluble and lipid-soluble antioxidants protect skin cells from immediate CEES-induced damage via attenuating oxidative stress. Liposomes containing water-soluble antioxidants and/or lipid-soluble antioxidants were evaluated using in vitro model systems. Initially, we found that liposomes containing encapsulated glutathione (GSH-liposomes) increased cell viability and attenuated production of reactive oxygen species (ROS) in HaCaT cells exposed to CEES. Next, GSH-liposomes were tested in a human epidermal model, EpiDerm. In the EpiDerm, GSH-liposomes administered simultaneously or 1 hour after CEES exposure (2.5 mM) increased cell viability, inhibited CEES-induced loss of ATP and attenuated changes in cellular morphology, but did not reduce caspase-3 activity. These findings paralleled the previously described in vivo protective effect of antioxidant liposomes in the rat lung and established the effectiveness of GSH-liposomes in a human epidermal model. This study provides a rationale for use of antioxidant liposomes against HD toxicity in the skin considering further verification in animal models exposed to HD.

Role of TNFR1 in lung injury and altered lung function induced by the model sulfur mustard vesicant, 2-chloroethyl ethyl sulfide

Lung toxicity induced by sulfur mustard is associated with inflammation and oxidative stress. To elucidate mechanisms mediating pulmonary damage, we used 2-chloroethyl ethyl sulfide (CEES), a model sulfur mustard vesicant. Male mice (B6129) were treated intratracheally with CEES (3 or 6 mg/kg) or control. Animals were sacrificed 3, 7 or 14 days later and bronchoalveolar lavage (BAL) fluid and lung tissue collected. Treatment of mice with CEES resulted in an increase in BAL protein, an indication of alveolar epithelial damage, within 3 days. Expression of Ym1, an oxidative stress marker also increased in the lung, along with inducible nitric oxide synthase, and at 14 days, cyclooxygenase-2 and monocyte chemotactic protein-1, inflammatory proteins implicated in tissue injury. These responses were attenuated in mice lacking the p55 receptor for TNFα (TNFR1-/-), demonstrating that signaling via TNFR1 is key to CEES-induced injury, oxidative stress, and inflammation. CEES-induced upregulation of CuZn-superoxide dismutase (SOD) and MnSOD was delayed or absent in TNFR1-/- mice, relative to WT mice, suggesting that TNFα mediates early antioxidant responses to lung toxicants. Treatment of WT mice with CEES also resulted in functional alterations in the lung including decreases in compliance and increases in elastance. Additionally, methacholine-induced alterations in total lung resistance and central airway resistance were dampened by CEES. Loss of TNFR1 resulted in blunted functional responses to CEES. These effects were most notable in the airways. These data suggest that targeting TNFα signaling may be useful in mitigating lung injury, inflammation and functional alterations induced by vesicants.

Protective actions of des-aspartate-angiotensin I in mice model of CEES-induced lung intoxication

The present study investigated the protective actions of des-aspartate-angiotensin I (DAA-I) in mice that were intranasally administered 2-chloroethyl ethyl sulfide (CEES), a half sulfur mustard. The protection was dose-dependent, and an oral dose of 75 mg kg⁻¹ per day administered 18 h post exposure and for the following 13 days, offered maximum protection that increased survival by a third. DAA-I attenuated the early processes of inflammation seen in the CEES-inoculated mice. DAA-I attenuated (i) elevated pulmonary ROS, and gp91-phox protein of NADPH oxidase, a non phagocytic enzyme that generates superoxide and subsequent ROS; (ii) intercellular adhesion molecule-1 (ICAM⁻¹) that is involved in the extravasation of circulating leucocytes; and (iii) myeloperoxidase activity, which is a surrogate enzymatic measurement of neutrophil infiltration. These actions led to improved histological lung structures, and survival of type-1 pneumocytes. The action of DAA-I on animal survival was blocked by losartan, a selective angiotensin AT1 receptor blocker, indicting that the AT1 receptor mediates the protection. The presence of elevated PGE2 and PGI2 in lung supernatants of DAA-I treated CEES-inoculated mice indicates that the two prostaglandins are involved in signaling the protective actions of DAA-I. This finding complements earlier studies showing that DAA-I acts on an indomethacin-sensitive angiotensin AT1 receptor. The findings of the present study are the first demonstration of an angiotensin peptide as an effective antidote for CEES intoxication. DAA-I is also an effective therapeutic intervention against CEES that was instituted at 18 h post exposure, and challenges conventional assumptions of limited efficacy with delayed action against alkylating agents.