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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., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Sulfur mustard (SM) inhalation causes debilitating pulmonary injury in humans which progresses to fibrosis. Herein, we developed a rat model of SM toxicity which parallels pathological changes in the respiratory tract observed in humans. SM vapor inhalation caused dose (0.2-0.6 mg/kg)-related damage to the respiratory tract within 3 days of exposure. At 0.4-0.6 mg/kg, ulceration of the proximal bronchioles, edema and inflammation were observed, along with a proteinaceous exudate containing inflammatory cells in alveolar regions. Time course studies revealed that the pathologic response was biphasic. Thus, changes observed at 3 days post-SM were reduced at 7-16 days; this was followed by more robust aberrations at 28 days, including epithelial necrosis and hyperplasia in the distal bronchioles, thickened alveolar walls, enlarged vacuolated macrophages, and interstitial fibrosis. Histopathologic changes were correlated with biphasic increases in bronchoalveolar lavage (BAL) cell and protein content and proliferating cell nuclear antigen expression. Proinflammatory proteins receptor for advanced glycation end product (RAGE), high-mobility group box protein (HMGB)-1, and matrix metalloproteinase (MMP)-9 also increased in a biphasic manner following SM inhalation, along with surfactant protein-D (SP-D). Tumor necrosis factor (TNF)-α and inducible nitric oxide synthase (iNOS), inflammatory proteins implicated in mustard lung toxicity, and the proinflammatory/profibrotic protein, galectin (Gal)-3, were upregulated in alveolar macrophages and in bronchiolar regions at 3 and 28 days post-SM. Inflammatory changes in the lung were associated with oxidative stress, as reflected by increased expression of heme oxygenase (HO)-1. These data demonstrate a similar pathologic response to inhaled SM in rats and humans suggesting that this rodent model can be used for mechanistic studies and for the identification of efficacious therapeutics for mitigating toxicity., (© The Author(s) 2020. Published by Oxford University Press on behalf of the Society of Toxicology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

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., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Sulfur mustard (SM) and nitrogen mustard (NM) are cytotoxic alkylating agents that cause severe and progressive injury to the respiratory tract, resulting in significant morbidity and mortality. Evidence suggests that macrophages and the inflammatory mediators they release play roles in both acute and long-term pulmonary injuries caused by mustards. In this article, we review the pathogenic effects of SM and NM on the respiratory tract and potential inflammatory mechanisms contributing to this activity., Competing Interests: The authors declare no conflicts of interest., (© 2016 New York Academy of Sciences.)

Pulmonary toxicity induced by sulfur mustard and related vesicants is associated with oxidative stress. In the present studies we analyzed the role of reactive nitrogen species (RNS) generated via inducible nitric oxide synthase (iNOS) in lung injury and inflammation induced by vesicants using 2-chloroethyl ethyl sulfide (CEES) as a model. C57Bl/6 (WT) and iNOS-/- mice were sacrificed 3 days or 14 days following intratracheal administration of CEES (6 mg/kg) or control. CEES intoxication resulted in transient (3 days) increases in bronchoalveolar lavage (BAL) cell and protein content in WT, but not iNOS-/- mice. This correlated with expression of Ym1, a marker of oxidative stress in alveolar macrophages and epithelial cells. In contrast, in iNOS-/- mice, Ym1 was only observed 14 days post-exposure in enlarged alveolar macrophages, suggesting that they are alternatively activated. This is supported by findings that lung tumor necrosis factor and lipocalin Lcn2 expression, mediators involved in tissue repair were also upregulated at this time in iNOS-/- mice. Conversely, CEES-induced increases in the proinflammatory genes, monocyte chemotactic protein-1 and cyclooxygenase-2, were abrogated in iNOS-/- mice. In WT mice, CEES treatment also resulted in increases in total lung resistance and decreases in compliance in response to methacholine, effects blunted by loss of iNOS. These data demonstrate that RNS, generated via iNOS play a role in the pathogenic responses to CEES, augmenting oxidative stress and inflammation and suppressing tissue repair. Elucidating inflammatory mechanisms mediating vesicant-induced lung injury is key to the development of therapeutics to treat mustard poisoning., (Copyright © 2012 Elsevier Inc. All rights reserved.)

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., (Copyright © 2010 Elsevier Inc. All rights reserved.)

Sulfur mustard (SM) is highly toxic to the lung inducing both acute and chronic effects including upper and lower obstructive disease, airway inflammation, and acute respiratory distress syndrome, and with time, tracheobronchial stenosis, bronchitis, and bronchiolitis obliterans. Thus it is essential to identify effective strategies to mitigate the toxicity of SM and related vesicants. Studies in animals and in cell culture models have identified key mechanistic pathways mediating their toxicity, which may be relevant targets for the development of countermeasures. For example, following SM poisoning, DNA damage, apoptosis, and autophagy are observed in the lung, along with increased expression of activated caspases and DNA repair enzymes, biochemical markers of these activities. This is associated with inflammatory cell accumulation in the respiratory tract and increased expression of tumor necrosis factor-α and other proinflammatory cytokines, as well as reactive oxygen and nitrogen species. Matrix metalloproteinases are also upregulated in the lung after SM exposure, which are thought to contribute to the detachment of epithelial cells from basement membranes and disruption of the pulmonary epithelial barrier. Findings that production of inflammatory mediators correlates directly with altered lung function suggests that they play a key role in toxicity. In this regard, specific therapeutic interventions currently under investigation include anti-inflammatory agents (e.g., steroids), antioxidants (e.g., tocopherols, melatonin, N-acetylcysteine, nitric oxide synthase inhibitors), protease inhibitors (e.g., doxycycline, aprotinin, ilomastat), surfactant replacement, and bronchodilators. Effective treatments may depend on the extent of lung injury and require a multi-faceted pharmacological approach., (Copyright © 2010 Elsevier Ltd. All rights reserved.)

Inhalation of sulfur mustard (SM), a bifunctional alkylating agent that causes severe lung damage, is a significant threat to both military and civilian populations. The mechanisms mediating its cytotoxic effects are unknown and were investigated in the present studies. Male rats Crl:CD(SD) were anesthetized, and then intratracheally intubated and exposed to 0.7-1.4mg/kg SM by vapor inhalation. Animals were euthanized 6, 24, 48h or 7days post-exposure and bronchoalveolar lavage fluid (BAL) and lung tissue collected. Exposure of rats to SM resulted in rapid pulmonary toxicity, including focal ulceration and detachment of the trachea and bronchial epithelia from underlying mucosa, thickening of alveolar septal walls and increased numbers of inflammatory cells in the tissue. There was also evidence of autophagy and apoptosis in the tissue. This was correlated with increased BAL protein content, a marker of injury to the alveolar epithelial lining. SM exposure also resulted in increased expression of markers of inflammation including cyclooxygenase-2 (COX-2), tumor necrosis factor-α (TNFα), inducible nitric oxide synthase (iNOS), and matrix metalloproteinase-9 (MMP-9), each of which has been implicated in pulmonary toxicity. Whereas COX-2, TNFα and iNOS were mainly localized in alveolar regions, MMP-9 was prominent in bronchial epithelium. In contrast, expression of the anti-oxidant hemeoxygenase, and the anti-inflammatory collectin, surfactant protein-D, decreased in the lung after SM exposure. These data demonstrate that SM-induced oxidative stress and injury are associated with the generation of cytotoxic inflammatory proteins which may contribute to the pathogenic response to this vesicant., (Copyright © 2010. Published by Elsevier Inc.)