Mustard lung and COPD: common features and treatment?

Divinyl sulfone, an oxidative metabolite of sulfur mustard, induces caspase-independent pyroptosis in hepatocytes

Sulfur mustard (SM) is a highly toxic blister agent which has been used many times in several wars and conflicts and caused heavy casualties. Ease of production and lack of effective therapies make SM a potential threat to public health. SM intoxication causes severe damage on various target organs, such as the skin, eyes, and lungs. In addition, SM exposure can also lead to hepatotoxicity and severe liver injuries. However, despite decades of research, the molecular mechanism underlying SM-induced liver damage remains obscure. SM can be converted into various products via complex hepatic metabolism in vivo. There are some pieces of evidence that one of the oxidation products of SM, divinyl sulfone (DVS), exhibits even more significant toxicity than SM. Nevertheless, the molecular toxicology of DVS is still hardly known. In the present study, we confirmed that DVS is even more toxic than SM in the human hepatocellular carcinoma cell line HepG2. Further mechanistic study revealed that DVS exposure (200 μM) promotes pyroptosis in HepG2 cells, while SM (400 μM) mainly induces apoptosis. DVS induces gasdermin D (GSDMD) mediated pyroptosis, which is independent of caspases activation but depends on the large amounts of reactive oxygen species (ROS) and severe oxidative stress produced during DVS exposure. Our findings may provide novel insights for understanding the mechanism of SM poisoning and may be helpful to discover promising therapeutic strategies for SM intoxication.

The role of sulfur compounds in chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is a common respiratory disease that brings about great social and economic burden, with oxidative stress and inflammation affecting the whole disease progress. Sulfur compounds such as hydrogen sulfide (H₂S), thiols, and persulfides/polysulfides have intrinsic antioxidant and anti-inflammatory ability, which is engaged in the pathophysiological process of COPD. Hydrogen sulfide mainly exhibits its function by S-sulfidation of the cysteine residue of the targeted proteins. It also interacts with nitric oxide and acts as a potential biomarker for the COPD phenotype. Thiols’ redox buffer such as the glutathione redox couple is a major non-enzymatic redox buffer reflecting the oxidative stress in the organism. The disturbance of redox buffers was often detected in patients with COPD, and redressing the balance could delay COPD exacerbation. Sulfane sulfur refers to a divalent sulfur atom bonded with another sulfur atom. Among them, persulfides and polysulfides have an evolutionarily conserved modification with antiaging effects. Sulfur compounds and their relative signaling pathways are also associated with the development of comorbidities in COPD. Synthetic compounds which can release H₂S and persulfides in the organism have gradually been developed. Naturally extracted sulfur compounds with pharmacological effects also aroused great interest. This study discussed the biological functions and mechanisms of sulfur compounds in regulating COPD and its comorbidities.

DNA damage and telomere length shortening in the peripheral blood leukocytes of 20 years SM-exposed veterans

Sulfur mustard (SM) is a vesicant chemical warfare agent, and a very potent alkylating agent. SM exerts its cytotoxicity via direct alkylation of biomacromolecules, and overproduction of reactive oxygen species (ROS). Previous studies have shown that SM-induced oxidative stress has adverse effects on antioxidant defense system, and damages lipids and proteins. The aim of this study was to investigate the effect of SM-induced oxidative stress on DNA damage, and cellular senescence in SM-exposed victims. For this purpose, MDA levels as a measure of oxidative stress in the serum, 8-oxo-dG content of the genomic DNA, and OGG1 expression as two biomarkers of oxidative DNA damage, as well as, telomere length, and p16^INK4a expression as two biomarkers of cellular senescence were measured in the peripheral blood leukocytes of 215 males who were exposed to SM 20 to 25 years ago, and 53 unexposed healthy males as the control group. Our results indicated that the levels of 8-oxo-dG, and OGG1 mRNA expression were significantly higher in SM-exposed individuals. Furthermore, a significant increase in the expression of p16^INK4a was observed in SM-exposed patients, and leukocyte telomere length (LTL) was also significantly shorter in severe/very severe cases of SM-exposed patients when compared with unexposed controls. In conclusion, our data indicate that oxidative DNA damage is higher in SM-exposed patients, and their immune system has subjected to cellular senescence.

Prooxidant-antioxidant balance in Iranian veterans exposed to mustard gas and its correlation with biochemical and hematological parameters

The present study aimed to evaluate serum prooxidant -antioxidant balance (PAB) in an Iranian population exposed to sulfur mustard (SM) more than 20 years ago. In this study, 42 SM-exposed subjects and 30 unexposed subjects (as controls) were recruited. Serum PAB, biochemical, and hematological parameters were measured in all subjects. Correlation of PAB with biochemical and hematological parameters was determined. The mean PAB values in the SM-exposed group (82.5 ± 34.8 HK) were significantly higher than that in the control group [47.5 ± 17.8 HK] (p < 0.001). The results demonstrated that serum PAB values were positively correlated with alkaline phosphatase activities in the SM-exposed group. Furthermore, PAB values showed a significant negative correlation with hepatic enzymes (AST, ALT), triglycerides, total bilirubin, and mean corpuscular hemoglobin concentrations. PAB values showed a borderline significant negative correlation with uric acid. The present results suggest that late oxidative stress and alterations in biochemical and hematological parameters may be a consequence of the frequent respiratory infections rather than direct toxic effects of SM.

Risks of on-pump coronary artery bypass grafting surgery in patients with chronic obstructive pulmonary disease due to sulfur mustard

Sulfur mustard (SM) is a toxic chemical agent that belongs to a class of vesicant compounds. In the 1980s it was used by the Iraqi army against Iranian forces. Sulfur mustard severely irritates the skin, eyes and lungs. The highest side effects seen in patients affected by this gas are pulmonary complications including different types of lung diseases such as bronchiolitis. It has also led to a certain type of chronic obstructive pulmonary disease called mustard lung. Similar extra-pulmonary, molecular and hormonal effects can be observed in these patients and patients with chronic obstructive pulmonary disease. Here cardiovascular complications may be one of the most dangerous visible effects. And atherosclerosis is probable following the direct effects or consequential long-term effects of SM. The development of atherosclerosis in these patients is associated with an increased risk of cardiovascular and coronary artery disease. Coronary artery bypass grafting surgery is the treatment of coronary artery disease. Doing this surgery by bypass pump has its own morbidity and due to local and systemic inflammation changes in patients with SM pulmonary disorders it may have more side effects. Therefore, detailed knowledge of inflammatory diseases as well as the serum level or even the local lung fluid of the inflammatory factors in these patients before surgery are needed so that it would be possible to reduce the rate of morbidity and mortality by normalizing the inflammatory conditions of the patients before cardiac surgery.