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

Pachymic Acid Protects Against Bleomycin-Induced Pulmonary Fibrosis by Suppressing Fibrotic, Inflammatory, and Oxidative Stress Pathways in Mice

Pachymic acid (PA), a natural extract from Poria cocos (Schw.) Wolf, possesses anti-inflammatory and anti-oxidative properties. However, it is still unknown whether PA can protect against bleomycin (BLM)-induced pulmonary fibrosis (PF). In this study, we investigated the effects of PA in mice administered BLM. Our results showed that PA significantly improved lung damage and pathological manifestations. Additionally, PA reduced the levels of interleukin (IL)-6 and tumor necrosis factor (TNF)-α, while increasing the level of IL-10. PA also decreased the levels of hydroxyproline and malondialdehyde, and increased the activities of superoxide dismutase and glutathione peroxidase in lung tissue. Furthermore, PA inhibited the increases in pyrin domain-containing protein 3 (NLRP3), ASC, IL-1β, P20, and TXNIP induced by BLM. In conclusion, our study demonstrated the protective effects of PA against BLM-induced PF in mice by suppressing fibrotic, inflammatory, and oxidative stress pathways.

Respiratory function after 30+ years following sulfur mustard exposure in survivors in Sweden

Background

Sulfur mustard (SM) exposure causes acute and chronic respiratory diseases. The extent of small airway dysfunction (SAD) in individuals exposed to SM is unclear. This study evaluated and compared SAD in SM-exposed and SM-unexposed participants using noninvasive lung function tests assessing small airway function.

Methods

This retrospective cohort study involved SM-exposed (n = 15, mean age: 53 ± 8 years) and SM-unexposed (n = 15, mean age: 53 ± 7 years) Kurdish-Swedish individuals in Sweden. Small airway resistance and reactance were assessed using impulse oscillometry (IOS). Nitrogen (N2) multiple breath washout (MBW) was employed to assess lung ventilation heterogeneity. The gas-exchanging capacity of the lungs was assessed using the diffusing capacity of the lungs for the carbon monoxide (DLCO) test. Lung function outcomes were reported as absolute values and z-scores. Group comparisons were performed using the Mann-Whitney U test.

Results

No statistically significant differences in age, height, or body mass index were observed between the two groups. IOS showed significantly increased small airway resistance, while N2MBW exhibited significantly increased global and acinar ventilation heterogeneity in SM-exposed individuals compared to that in unexposed individuals. SAD was identified in 14 of 15 SM-exposed individuals, defined as at least one abnormal IOS difference between resistance at 5 and 20 Hz (R5-R20) and/or area of reactance (AX) or N2MBW lung's acinar zone (Sacin), and DLCO adjusted to the alveolar volume (DLCO/VA) outcome. Of these 14 individuals, only 5 demonstrated concordant findings across the IOS and N2MBW tests.

Conclusion

Exposure to SM was positively associated with long-term impairment of respiratory tract function in the small airways in the majority of the previously SM-exposed individuals in the present study. Furthermore, both IOS and N2MBW should be employed to detect SAD in SM-exposed survivors as they provide complementary information. Identifying and characterizing the remaining pathology of the small airways in survivors of SM exposure is a first step toward improved treatment and follow-up.

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.

Evaluation of the effects of dexamethasone in modulating breathing pattern decomplexification in rats with 2-chloroethyl ethyl sulfide-induced lung injury

"Background and Objectives: Sulfur mustard is a functional alkylating chemical warfare agent that gives rise to appalling lung injury. In people with pulmonary diseases, including asthma, the complication of respirational dynamics is reduced. However, the complexity of breathing patterns in lung injury caused by chemical agents is not clear. In the current study, the outcome of 2-chloroethyl ethyl sulfide (CEES), and mustard analogue, upon breathing pattern of rats without or with treatment were reviewed. Methods: The interbeat interval (IBI) and respiratory volume (RV) data have been acquired from spontaneous respiration rats with lung injury by CEES using a whole-body plethysmograph. We calculated mean and coefficient of variation, alpha exponent derived from detrended fluctuation analysis (DFA), and sample entropy of IBI and RV. Finding: Entropy examination of respiratory variation displayed reduced inconsistency (less complication) in the breathing pattern of this rat model of lung injury. The mustard analogue also led to increased lung inflammation in damaged rats. However, treatment by NAC and dexamethasone had a compelling impact on the complication of the breathing rhythm and lung inflammation of rats with lung injury. Conclusion: Our findings show that inflammation could be the possible origin of respiratory dynamics shifting apart from the normal variation in CEES-induced lung injury"

Possible Treatment Approaches of Sulfur Mustard-Induced Lung Disorders, Experimental and Clinical Evidence, an Updated Review

Sulfur mustard (SM) is one of the major potent chemical warfare that caused the death of victims in World War I and the Iraq-Iran conflict (1980-1988). The respiratory system is the main target of SM exposure and there are no definitive therapeutic modalities for SM-induced lung injury. The effects of the new pharmaceutical drugs on lung injury induced by SM exposure were summarized in this review. Literature review on PubMed, ScienceDirect, and Google Scholar databases was performed to find papers that reported new treatment approach on SM-exposure-induced injury in the respiratory system until October 2019. The search was restricted to sulfur mustard AND induced injury (in vitro studies, animal experiments, and clinical trials) AND respiratory system OR lung, AND treatment in all fields. Two hundred and eighty-three relevant articles were identified that 97 retrieved articles were eligible and were included in the review. Some new pharmaceutical drugs have shown therapeutic potential in controlling various characteristics of lung injury due to SM exposure. Recent studies showed therapeutic effects of mucolytic drugs, non-steroidal drugs, and antibiotics on reducing lung inflammation, oxidative stress responses, and modulating of the immune system as well as improving of respiratory symptoms and pulmonary function tests. Studies on the therapeutic effects of new agents with amelioration or treatment of SM-induced lung injury were reviewed and discussed.

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

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

Possible treatment with medicinal herbs and their ingredients of lung disorders induced by sulfur mustard exposures: a review

Chemical warfare (CW) agents are toxic synthetic chemicals that affect human's health, and sulfur mustard (SM) is a well-known chemical weapon that caused deaths of victims. The lung is the main target of SM exposure, and there are no definitive therapeutic modalities for lung injury induced by this agent. The possible therapeutic effects of medicinal plants and their active ingredients on lung injury induced by SM were reviewed in this article until the end of June 2021. Medicinal plants including Crocus sativus, Curcuma longa, Thymus vulgaris, Nigella sativa, and Zataria multiflora and also natural compounds showed therapeutic potential in improving of various features of lung injury induced by SM and other related chemical agents. Several studies showed therapeutic effects of some medicinal plants and natural products on lung inflammation, oxidative stress, and immune responses in experimental studies in SM-induced lung injury. In addition, clinical studies also showed the effect of medicinal plants and natural compounds on respiratory symptoms, pulmonary function tests (PFTs), and inflammatory markers. The therapeutic effects of medicinal plants and natural products on lung disorder induced by SM and related chemical agents were shown through amelioration of various features of lung injury.

Therapeutic Effect of Neuraminidase-1-Selective Inhibition in Mouse Models of Bleomycin-Induced Pulmonary Inflammation and Fibrosis

Pulmonary fibrosis remains a serious biomedical problem with no cure and an urgent need for better therapies. Neuraminidases (NEUs), including NEU1, have been recently implicated in the mechanism of pulmonary fibrosis by us and others. We now have tested the ability of a broad-spectrum neuraminidase inhibitor, 2,3-dehydro-2-deoxy-N-acetylneuraminic acid (DANA), to modulate the in vivo response to acute intratracheal bleomycin challenge as an experimental model of pulmonary fibrosis. A marked alleviation of bleomycin-induced body weight loss and notable declines in accumulation of pulmonary lymphocytes and collagen deposition were observed. Real-time polymerase chain reaction analyses of human and mouse lung tissues and primary human lung fibroblast cultures were also performed. A predominant expression and pronounced elevation in the levels of NEU1 mRNA were observed in patients with idiopathic pulmonary fibrosis and bleomycin-challenged mice compared with their corresponding controls, whereas NEU2, NEU3, and NEU4 were expressed at far lower levels. The levels of mRNA for the NEU1 chaperone, protective protein/cathepsin A (PPCA), were also elevated by bleomycin. Western blotting analyses demonstrated bleomycin-induced elevations in protein expression of both NEU1 and PPCA in mouse lungs. Two known selective NEU1 inhibitors, C9-pentyl-amide-DANA (C9-BA-DANA) and C5-hexanamido-C9-acetamido-DANA, dramatically reduced bleomycin-induced loss of body weight, accumulation of pulmonary lymphocytes, and deposition of collagen. Importantly, C9-BA-DANA was therapeutic in the chronic bleomycin exposure model with no toxic effects observed within the experimental timeframe. Moreover, in the acute bleomycin model, C9-BA-DANA attenuated NEU1-mediated desialylation and shedding of the mucin-1 ectodomain. These data indicate that NEU1-selective inhibition offers a potential therapeutic intervention for pulmonary fibrotic diseases. SIGNIFICANCE STATEMENT: Neuraminidase-1-selective therapeutic targeting in the acute and chronic bleomycin models of pulmonary fibrosis reverses pulmonary collagen deposition, accumulation of lymphocytes in the lungs, and the disease-associated loss of body weight-all without observable toxic effects. Such therapy is as efficacious as nonspecific inhibition of all neuraminidases in these models, thus indicating the central role of neuraminidase-1 as well as offering a potential innovative, specifically targeted, and safe approach to treating human patients with a severe malady: pulmonary fibrosis.

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.

The effect of Zataria multiflora on inflammatory cytokine and respiratory symptoms in veterans exposed to sulfur mustard

The effect of Zataria multiflora (Z. multiflora) on serum cytokine, chemokines, and respiratory symptoms in the veterans exposed to sulfur mustard (SM) more than two decades (27-30 years) ago was conducted in 2018. Thirty-four patients were randomly assigned to the placebo group (P, mean age (54.40 ± 5.51)) and two treated groups with Z. multiflora extract 5 and 10 mg/kg/day (Z5 and 10; mean age, 58.50 ± 3.60 and 55.18 ± 4.11, respectively). Serum levels of tumor necrosis factor (TNF-α), monocyte chemotactic protein 1 (MCP-1), vascular endothelial growth factor (VEGF), epidermal growth factor (EGF), forced expiratory volume-one second (FEV₁), and respiratory symptoms including chest wheeze (CW), night wheeze (NW), night cough (NC), and cough and wheeze during exercise (ECW) were assessed at the baseline (phase 0), 1 and 2 months after starting treatment (phase I and II, respectively). The value of FEV₁ was significantly increased in Z10 in phase I and II compared with that in phase 0 (p < 0.01 for both) and in Z5 in phase II compared with phase I and 0 (p < 0.001for both). All respiratory symptoms significantly decreased in Z5 and 10 in phase I and II compared with those in phase 0 (p < 0.05 to p < 0.001). Serum levels of TNF-α and VEGF were decreased in Z5 and 10 in phase I and II compared with those in phase 0 (p < 0.05 to p < 0.001). Serum levels of MCP-1 and EGF were decreased in Z10 in phase I and II compared with those in phase 0 (p < 0.05 to p < 0.001). The percent change of respiratory symptoms, serum levels of cytokines during the treatment period, was significantly improved in the treated groups compared with that in the placebo group. Two months' of treatment with Z. multiflora improved cytokine levels, respiratory symptom, and FEV₁ values in SM-exposed patients.

Effect of Zataria multiflora on serum cytokine levels and pulmonary function tests in sulfur mustard-induced lung disorders: A randomized double-blind clinical trial

ETHNOPHARMACOLOGICAL RELEVANCE

Zataria multiflora (Z. multiflora) belongs to the Lamiaceae family and has several traditional uses owing to its antiseptic, aesthetic, antispasmodic, analgesic, and antidiarrheal properties.

AIM OF THE STUDY

We aimed to investigate the effect of Z. multiflora on serum cytokine levels and pulmonary function tests (PFT) in patients exposed to sulfur mustard (SM) for a long term (27-30 years).

MATERIALS AND METHODS

Thirty-five patients were randomly assigned to the placebo group (P) and two experimental groups treated with Z. multiflora extracts, i.e., 5 and 10 mg/kg/day (Z5 and Z10). Serum levels of cytokines including IL (2, 4, 6, 8, and 10) and IFN-γ as well as PFT indices such as maximum mid-expiratory flow (MMEF) and maximum expiratory flow at 25, 50, and 75% of vital capacity (VC) (MEF25, 50, and 75) were assessed at the beginning (phase 0) and at the end of 4 and 8 weeks (phases I and II, respectively) after starting the treatment.

RESULTS

Serum levels of IL-2, IL-6, and IL-8 were significantly decreased, while serum levels of IL-10 and IFN-γ were significantly increased in the Z5 and Z10 treatment groups in phases I and II as compared to those in phase 0 (p < 0.05 to p < 0.001). MMEF and MEF25, 50, and 75 values were significantly increased in the Z5 group in phase II and in the Z10 group in phases I and II compared to those in phase 0 (p < 0.05 to p < 0.001). The percent change in serum cytokine levels and the change in MEF25, 50, and 75 during the two-month treatment period were significantly higher in the treatment groups than in the placebo group.

CONCLUSIONS

Two months of treatment with Z. multiflora reduced inflammation, while it enhanced anti-inflammatory cytokines and improved PFT indices in SM-exposed patients.

Acute intensive care unit management of mustard gas victims: the Turkish experience. Cutan Ocul Toxicol 2018;37:332-337. [PMID: 29648477 DOI: 10.1080/15569527.2018.1464018]

PURPOSE

Sulphur mustard (SM) is an highly toxic and vesicant chemical weapon that was used in various military conflicts several times in the history. The severity of ocular, dermal, and pulmonary symptoms that may appear following a characteristic asymptomatic period are depending on the SM concentration and exposure duration. The aim of this study is to present the clinical features and share the intensive care unit (ICU) experiences for the medical management of mustard gas victims.

MATERIALS AND METHODS

Thirteen Free Syrian Army soldiers near Al-Bab region of North Syria were reportedly exposed to oily blackish smoke with garlic smell due to the explosion of a trapped bomb without causing any blast or thermal effect on 26th November 2016. None of them wore any chemical protective suits or gas masks during explosion. Since they observed skin lesions including bullous formation next day, they were admitted to the Turkish Field Hospital at the Turkish - Syrian border and then evacuated to the State Hospital of Gaziantep Province, Turkey for further management. Eight victims who were very close to point of explosion suffered burning eyes, sore throat, dry cough and dyspnoea after the chemical attack.

RESULTS

On admission to hospital, all cases had conjunctivitis, hoarseness and bullae on various body areas. Blepharospasm and opacity were found in 8 patients and 5 of them had corneal erosions and periorbital oedema. Temporary loss of vision in 4 cases lasted for 24 h. Multiple fluid-filled blisters were observed especially on the scalp, neck, arms and hands, where direct skin exposure to the agent occurred. A definitive clinical care and infection prophylaxis measures along with the burn treatment and bronchodilators for respiratory effects were applied in ICU. Two patients received granulocyte-colony-stimulating factor due to the SM-mediated bone marrow suppression on the 16th day of exposure and one of them died because of necrotic bronchial pseudomembrane obstruction resulting in cardiopulmonary arrest.

CONCLUSIONS

SM was first used during the First World War and it is still considered one of the major chemical weapons recently used by non-state actors in Syria and Iraq. In case of SM exposure, medical treatment of SM-induced lesions is symptomatic because no antidote or causal therapy does exist even though SM is very well known for over 100 years. However, clinical management in intensive care medicine of SM victims have improved since the 1980s, this study which is one of the largest recent SM-exposed case series since that time is important for the contribution to the clinical experience.

Free Radical Production and Oxidative Stress in Lung Tissue of Patients Exposed to Sulfur Mustard: An Overview of Cellular and Molecular Mechanisms

Sulfur mustard (SM) is a chemical alkylating compound that primary targets lung tissue. It causes a wide variety of pathological effects in respiratory system such as chronic bronchitis, bronchiolitis obliterans, necrosis of the mucosa and inflammation, chronic obstructive pulmonary disease (COPD), and pulmonary fibrosis. However, molecular and cellular mechanisms for these pathologies are still unclear. Oxidative stress (OS) induced by reactive oxygen species (ROS) is likely a significant mechanism by which SM leads to cell death and tissues injury. SM can trigger various molecular and cellular pathways that are linked to ROS generation, OS, and inflammation. Hypoxia-induced oxidative stress, reduced activity of enzymatic antioxidants, depletion of intercellular glutathione (GSH), decreased productivity of GSH-dependent antioxidants, mitochondrial dysfunction, accumulation of leukocytes and proinflammatory cytokines, and increased expression of ROS producing-related enzymes and inflammatory mediators are the major events in which SM leads to massive production of ROS and OS in pulmonary system. Therefore, understanding of these molecules and signaling pathways gives us valuable information about toxicological effects of SM on injured tissues and the way for developing a suitable clinical treatment. In this review, we aim to discuss the possible mechanisms by which SM induces excessive production of ROS, OS, and antioxidants depletion in lung tissue of exposed patients.

Carvacrol ameliorates haematological parameters, oxidant/antioxidant biomarkers and pulmonary function tests in patients with sulphur mustard-induced lung disorders: A randomized double-blind clinical trial

WHAT IS KNOWN AND OBJECTIVE

In this study, the effect of carvacrol (CAR) on pulmonary function tests (PFT), haematological indices and oxidant/antioxidant biomarkers in patients with sulphur mustard (SM)-induced lung disorders was examined.

METHODS

Twenty patients exposed to SM 27-30 years ago were divided into two groups and treated with either placebo (P) or CAR (1.2 mg/kg per day) (n = 10 for each group). Forced vital capacity (FVC), peak expiratory flow (PEF), total and different white blood cell (WBC), haematological parameters and oxidant/antioxidant biomarkers were measured at the baseline (step 0), one and two months (steps I and II, respectively) after starting the treatment.

RESULTS AND DISCUSSION

PEF was significantly increased in the CAR-treated group in step II compared to step 0 (P < .01). Total WBC (P < .01) and neutrophil (P < .05) count in the CAR-treated group were significantly decreased in the group in steps I and II (P < .01 for both cases) compared to step 0. The levels of thiol, superoxide dismutase and catalase in the CAR-treated group were significantly increased (P < .05 to P < .001) in steps I and II, but malondialdehyde significantly decreased in step II compared to step 0 (P < .01). The percentage of total and differential WBC, oxidant/antioxidant biomarkers, FVC and PEF values following a two-month treatment period were significantly improved in the CAR-treated group compared to the placebo group (P < .05 to P < .001).

WHAT IS NEW AND CONCLUSION

Two-month treatment with CAR reduced inflammatory cells and oxidant biomarkers, whereas increased antioxidant biomarkers and improved PFT tests in SM-exposed patients.

Th17/Treg immunoregulation and implications in treatment of sulfur mustard gas-induced lung diseases

INTRODUCTION

Sulfur mustard (SM) is an extremely toxic gas used in chemical warfare to cause massive lung injury and death. Victims exposed to SM gas acutely present with inhalational lung injury, but among those who survive, some develop obstructive airway diseases referred to as SM-lung syndrome. Pathophysiologically, SM-lung shares many characteristics with smoking-induced chronic obstructive pulmonary disease (COPD), including airway remodeling, goblet cell metaplasia, and obstructive ventilation defect. Some of the hallmarks of COPD pathogenesis, which include dysregulated lung inflammation, neutrophilia, recruitment of interleukin 17A (IL -17A) expressing CD4⁺T cells (Th17), and the paucity of lung regulatory T cells (Tregs), have also been described in SM-lung. Areas covered: A literature search was performed using the MEDLINE, EMBASE, and Web of Science databases inclusive of all literature prior to and including May 2017. Expert commentary: Here we review some of the recent findings that suggest a role for Th17 cell-mediated inflammatory changes associated with pulmonary complications in SM-lung and suggest new therapeutic approaches that could potentially alter disease progression with immune modulating biologics that can restore the lung Th17/Treg balance.

From the Cover: Catalytic Antioxidant Rescue of Inhaled Sulfur Mustard Toxicity

Sulfur mustard (bis 2-chloroethyl ethyl sulfide, SM) is a powerful bi-functional vesicating chemical warfare agent. SM tissue injury is partially mediated by the overproduction of reactive oxygen species resulting in oxidative stress. We hypothesized that using a catalytic antioxidant (AEOL 10150) to alleviate oxidative stress and secondary inflammation following exposure to SM would attenuate the toxic effects of SM inhalation. Adult male rats were intubated and exposed to SM (1.4 mg/kg), a dose that produces an LD₅₀ at approximately 24 h. Rats were randomized and treated via subcutaneous injection with either sterile PBS or AEOL 10150 (5 mg/kg, sc, every 4 h) beginning 1 h post-SM exposure. Rats were euthanized between 6 and 48 h after exposure to SM and survival and markers of injury were determined. Catalytic antioxidant treatment improved survival after SM inhalation in a dose-dependent manner, up to 52% over SM PBS at 48 h post-exposure. This improvement was sustained for at least 72 h after SM exposure when treatments were stopped after 48 h. Non-invasive monitoring throughout the duration of the studies also revealed blood oxygen saturations were improved by 10% and clinical scores were reduced by 57% after SM exposure in the catalytic antioxidant treatment group. Tissue analysis showed catalytic antioxidant therapy was able to decrease airway cast formation by 69% at 48 h post-exposure. To investigate antioxidant induced changes at the peak of injury, several biomarkers of oxidative stress and inflammation were evaluated at 24 h post-exposure. AEOL 10150 attenuated SM-mediated lung lipid oxidation, nitrosative stress and many proinflammatory cytokines. The findings indicate that catalytic antioxidants may be useful medical countermeasure against inhaled SM exposure.