Effect of sulfur mustard on murine lymphocytes

A Rodent Model of Sulfur Mustard Hematologic Toxicity for the Efficacy Evaluation of Candidate Medical Countermeasures

INTRODUCTION

While exposure to sulfur mustard (SM) is commonly associated with the production of vesicating dermal, ocular, and respiratory injuries, systemic damage to bone marrow and lymphatic tissue can decrease critical immune cell populations leading to higher susceptibility to life-threatening infection and septicemia. There are currently no approved medical countermeasures for SM-induced myelosuppression. An intravenous SM challenge model was developed in adult rats as a preliminary proof-of-principle platform to evaluate the efficacy of candidate immunostimulants.

MATERIALS AND METHODS

Adult male and female Sprague Dawley rats were exposed to SM through tail vein injection. Toxicity progression was monitored through clinical observations, body weights, body temperatures, hematology, serum clinical chemistry, and flow cytometry of blood and bone marrow samples.

RESULTS

Following SM exposure, overt toxicity progression was characterized by weight loss, changes in body temperature, and manifestation of toxic clinical signs (diarrhea, lethargy, hunched posture, rough hair coat, respiratory distress, and death). Drastic alterations in complete blood cell profiles included an early-onset lymphopenia followed by a delayed-onset neutropenia and thrombocytopenia. Only transient changes in serum clinical chemistry parameters were observed. Flow cytometry analysis of circulating blood revealed that B-cells were more predominantly affected by SM exposure than T-cells. Challenge with SM resulted in loss of hematopoietic and mesenchymal stem cell populations in the bone marrow.

CONCLUSIONS

The small animal model developed in this study replicates many key aspects of human SM exposures and should serve as a relevant, rapid, and cost-effective platform to screen candidate medical countermeasures for SM-induced hematologic toxicity.

Long-term health effects of chemical warfare agents on children following a single heavy exposure

In the 1980s, villages in the Kurdistan region of Iraq were exposed to chemical weapons (CWs), which killed and injured thousands of civilians. There has been no clinical assessment of the long-term effects of CWs exposure on those injured. We report the first such evaluation of CW effects on long-term health of children. Patients from the CW-exposed areas were interviewed to assess previous and current clinical history and underwent clinical examination. The status of organs known to be targets of CWs, including skin, eyes, respiratory and neuromuscular systems, was assessed. Children of similar age and social background, but with no history of CW exposure, were selected as a control population. Results showed that 70% of children in the CWs group had chronic health problems in contrast to 3.3% in the unexposed group ( p < 0.0001). Fifty-five per cent of the CW-exposed group had long-term visual impairment but none in the unexposed population. Thirty-six per cent of the CW-exposed group had chronic dermatological conditions compared with 0.8% of the unexposed group ( p < 0.0001), 31% of the CWs group had neurological sequelae compared with 0.4% of the unexposed group ( p < 0.0001) and 51% of the CWs group had long-term respiratory problems compared with 1.5% of the unexposed group ( p < 0.0001). Respiratory complaints including asthma, chronic bronchitis and bronchiectasis were particularly common. Our study suggests that CWs used were probably a combination of sulphur mustard and organophosphate nerve agents. Results also indicate that the prevalence of acute and chronic health problems following exposure to CW agents appear to be higher in children compared with reported data in adults.

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.

Topical nitrogen mustard exposure causes systemic toxic effects in mice

Vesicating agents sulfur mustard (SM) and nitrogen mustard (NM) are reported to be easily absorbed by skin upon exposure causing severe cutaneous injury and blistering. Our studies show that topical exposure of NM (3.2mg) onto SKH-1 hairless mouse skin, not only caused skin injury, but also led to significant body weight loss and 40-80% mortality (120 h post-exposure), suggesting its systemic effects. Accordingly, further studies herein show that NM exposure initiated an increase in circulating white blood cells by 24h (neutrophils, eosinophils and basophils) and thereafter a decrease (neutrophils, lymphocytes and monocytes). NM exposure also reduced both white and red pulp areas of the spleen. In the small intestine, NM exposure caused loss of membrane integrity of the surface epithelium, abnormal structure of glands and degeneration of villi. NM exposure also resulted in the dilation of glomerular capillaries of kidneys, and an increase in blood urea nitrogen/creatinine ratio. Our results here with NM are consistent with earlier reports that exposure to higher SM levels can cause damage to the hematopoietic system, and kidney, spleen and gastrointestinal tract toxicity. These outcomes will add to our understanding of the toxic effects of topical vesicant exposure, which might be helpful towards developing effective countermeasures against injuries from acute topical exposures.

The injury progression of T lymphocytes in a mouse model with subcutaneous injection of a high dose of sulfur mustard

BACKGROUND

In clinical studies, the findings on sulfur mustard (SM) toxicity for CD3(+)CD4(+) and CD3(+)CD8(+) T lymphocyte subsets are contradictory. In animal experiments, the effect of SM on the T cell number and proliferation is incompatible and is even the opposite of the results in human studies. In this study, we observed the dynamic changes of T lymphocytes in the first week in a high-dose SM-induced model.

METHODS

Mice were exposed to SM by subcutaneous injection (20 mg/kg) and were sacrificed 4 h, 24 h, 72 h and 168 h later. Spleen T lymphocyte proliferation was evaluated by (3)H-TdR. Flow cytometric analysis was used to observe the percentage of CD3(+)CD4(+) and CD3(+)CD8(+) T lymphocyte subsets. The IL-1β, IL-6, IL-10 and TNF-α levels in plasma were assayed using the Luminex method. DNA damage in bone marrow cells was observed with the single cell gel electrophoresis technique (SCGE).

RESULTS

SM continuously inhibited the proliferation of lymphocytes for 7 days, and there was a significant rebound of Con A-induced T lymphocyte proliferation only at 24 h. The percentage of CD3(+)CD4(+) and CD3(+)CD8(+) lymphocytes was upregulated, which was accompanied by increased IL-1β and TNF-α and decreased IL-10. The IL-6 level was gradually decreased in the PG group at 4 h. The peak of lymphocytic apoptosis and DNA damage occurred at 24 h and 72 h, respectively.

CONCLUSION

Our results show that SM significantly inhibited T lymphocyte proliferation as well as induced CD3(+)CD4(+) and CD3(+)CD8(+) upregulation. SM intoxication also significantly increased the levels of pro-inflammatory cytokines (IL-1β, IL-6 and TNF-α) and inhibited the level of anti-inflammatory cytokine IL-10. Our results may partly be due to the significant SM induced significant apoptosis and necrosis of lymphocytes as well as DNA damage of bone marrow cells. The results provided a favorable evaluation of SM immune toxicity in an animal model.

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.

Mustard gas toxicity: the acute and chronic pathological effects

Ever since it was first used in armed conflict, mustard gas (sulfur mustard, MG) has been known to cause a wide range of acute and chronic injuries to exposure victims. The earliest descriptions of these injuries were published during and in the immediate aftermath of the First World War, and a further series of accounts followed the Second World War. More recently, MG has been deployed in warfare in the Middle East and this resulted in large numbers of victims, whose conditions have been studied in detail at hospitals in the region. In this review, we bring together the older and more recent clinical studies on MG toxicity and summarize what is now known about the acute and chronic effects of the agent on the eyes, skin, respiratory tract and other physiological systems. In the majority of patients, the most clinically serious long-term consequences of MG poisoning are on the respiratory system, but the effects on the skin and other systems also have a significant impact on quality of life. Aspects of the management of these patients are discussed.

Cutaneous challenge with chemical warfare agents in the SKH-1 hairless mouse. (I) Development of a model for screening studies in skin decontamination and protection

Exposure to lethal chemical warfare agents (CWAs) is no longer only a military issue due to the terrorist threat. Among the CWAs of concern are the organophosphorus nerve agent O-ethyl-S-(2[di-isopropylamino]ethyl)methyl-phosphonothioate (VX) and the vesicant sulfur mustard (SM). Although efficient means of decontamination are available, most of them lose their efficacy when decontamination is delayed after exposure of the bare skin. Alternatively, CWA skin penetration can be prevented by topical skin protectants. Active research in skin protection and decontamination is thus paramount. In vivo screening of decontaminants or skin protectants is usually time consuming and may be expensive depending on the animal species used. We were thus looking for a suitable, scientifically sound and cost-effective model, which is easy to handle. The euthymic hairless mouse Crl: SKH-1 (hr/hr) BR is widely used in some skin studies and has previously been described to be suitable for some experiments involving SM or SM analogs. To evaluate the response of this species, we studied the consequences of exposing male anaesthetized SKH-1 mice to either liquid VX or to SM, the latter being used in liquid form or as saturated vapours. Long-term effects of SM burn were also evaluated. The model was then used in the companion paper (Taysse et al.(1)).

Delayed haematological complications of mustard gas

Haematopoiesis could be affected by mustard gas. We randomly selected 318 chemical victims exposed to mustard gas and compared their cell blood counts and peripheral blood smears (PBS) with those of 377 healthy men, and also various haematological indices of 57 of these victims compared with previous data 5 years ago. The average number of red blood cells and haemoglobin of victims compared with the controls was not significantly different, but they were increased compared with data from 5 years ago. White blood cell counts, neutrophils and lymphocytes did not show any clinically meaningful difference compared with the control group but 20 cases with atypical lymphocytes in their PBS have been found. Change in lymphocyte shape may be related to committed stem cell involvement. Further studies on bone marrow cells and cell markers are needed to document this hypothesis. The mild increase in erythroid cells and haemoglobin concentration may be due to chronic obstructive pulmonary disorder and other respiratory diseases in these patients.

[Acute poisoning by chemical warfare agent: sulfur mustard]

OBJECTIVE

To review story, mechanism of action, clinical and therapeutic bases of a sulfur mustard poisoning, by accidental, terrorism or war exposure.

DATA SOURCES

References were obtained from computerised bibliographic research (Medline), from personnel data (academic memoir, documents under approbation of the National Defense Office) and from the Library of Military Medical Service.

DATA SYNTHESIS

Sulfur mustard is a chemical warfare agent with peace time results: leak, accidental handling, acts of terrorism. Sulfur mustard is a vesicant agent, an organochlorine agent, who alkylate DNA. Under liquid or gas form its main target are skin and lungs. Clinical effects are like burns with loss of immunity, with respiratory failure, ophthalmic, gastrointestinal and haematological signs. The last studies have improved knowledge about the mechanism of action, detection, protection and treatment. Methods for determination of sulfur mustard are based on gas chromatographic method and mass spectrometry. During sulfur mustard contamination the first priorities of treatment are to remove victims from the contaminated place and to initiate decontamination. Emergency workers and materials must take protection to avoid secondary contamination of emergency unit. With treatment of vital functions and respiratory failure, the new ways of treatment are about N-acetyl cysteine for lung injury, poly (ADP-ribose) polymerase inhibitors, calmodulin antagonists and Ca(++) chelators. Interactions between sulfur mustard and anaesthetic agents are not well known and are based on clinical observations.

CONCLUSION

Emergency care unit can be confronted with sulfur mustard during accidental contamination or acts of terrorism. First and most efficacy priorities of treatment are to remove and to decontaminate victims. New means of detection and treatment are studied since several years but are not still appropriate to human victims or mass treatment.

Modeling for immunosupression by sulfur mustard

The treatment and cure of patients exposed to sulfur mustard is a remaining challenge despite on-going research in this field. A severe suppression of the immune system still remains the major cause of opportunistic infections, septicemia and death in patients injured by sulfur mustard. In this report, we present a model of sulfur mustard contamination in mice, which exhibit clinical signs similar to that exhibited by patients during the Iran-Iraq war. Dose response studies were performed to determine the most appropriate dose for our model i.e., 6.35 micrograms/kg. Animals contaminated with sulfur mustard intraperitoneally showed symptoms of anorexia, diarrhea, loss of weight and blindness. Autopsy of animals showed a severe necrosis in gut and degeneration of spleen. Results shows that sulfur mustard caused an over all suppression of the immune response to sRBC as indicated by agglutination titer and DTH tests. These studies present a rodent model of sulfur mustard exposure, which can be used for further studies in this area.

Apoptosis as a mechanism of 2-chloroethylethyl sulfide-induced cytotoxicity

Apoptosis is a mode of active cell death. We have examined whether 2-chloroethylethyl sulfide (CEES), a sulfur vesicating agent, triggers apoptosis as a cytotoxic mechanism. Incubation of thymocytes with CEES, resulted in an induction of apoptotic features of cell death. Treatment of cells with 100 microM CEES for 5 h increased DNA fragmentation to approximately 40% of control. The fragmentation of DNA was visualized by agarose gel electrophoresis. It showed ladder pattern of DNA fragmentation, which indicates internucleosomal cleavage of DNA. Further evidence of apoptosis was observed in morphological changes of nuclei by using the terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL) method. The percentage of TUNEL positive cells was dependent upon CEES concentrations. CEES induced the classical morphological features of apoptosis in nucleus. These features were accompanied by condensation of chromatin, which arranged in sharply declined clumps and fragmentation of nucleus. To study requirement for synthesis of new protein in CEES-induced apoptosis, we studied the effect of cycloheximide for apoptotic activity. This protein synthesis inhibitor did not suppress the CEES-induced apoptotic activity. Taken together, these results suggest that CEES-induced apoptosis as a cytotoxicmechanism and this process occurs independent of synthesis of new protein.

Change in glutathione S-transferase and glyceraldehyde-3-phosphate dehydrogenase activities in the organs of mice treated with 2-chloroethyl ethyl sulfide or its oxidation products

Various organs or skin from male ICR mice treated intraperitoneally with 2-chloroethyl ethyl sulfide (CEES) or its oxidation derivatives 2-chloroethyl ethyl sulfoxide (CESSO) and 2-chloroethyl ethyl sulfone were analysed for changes in two thiol-containing enzymes, namely glutathione S-transferase (GST) and glyceraldehyde-3-phosphate dehydrogenase (GAPDH). CEES was more potent than its oxidation derivatives with respect to the decrease in organ weight and the loss in GAPDH activity, although the reverse was found in GST induction. Whereas the induction of GST was highest in the lung after multiple intraperitoneal intoxication with CEESO (8 and 32 mg/kg), the decrease in GAPDH activity after exposure to CEES (8 mg/kg body weight) was most remarkable in the spleen, the most susceptible organ to toxicity of CEES. GST and GAPDH activities in the skin of male hairless mice exposed subcutaneously to CEES (2 mg/kg body weight) were not altered significantly at 2-hr exposure, but decreased up to 60% of that of controls at 8 hr, when oedema formation was greatest. Taken together, it appears that GAPDH activity is a more sensitive biochemical parameter than GST activity in organs of mice treated with CEES or its oxidation products.

Dose dependent effects on lymphoid organs following a single dermal application of sulphur mustard in mice

The effects of a single dermal application of sublethal doses [15.5, 7.75 and 3.88 mg kg-1] of bis(2-chloroethyl)sulphide [sulphur mustard, SM] on body weight, organ/body weight ratio, haematology, histology and cellularity of spleen and thymus were studied after 7 days, in Balb/c mice. A progressive fall in body weight was noticed from the fifth day onwards after SM treatment. A dose-dependent decrease in the relative weights of spleen, liver and peripheral lymph nodes, and an increase in adrenal weight were also seen. An increase in red blood cell count, packed cell volume and haemoglobin concentration following SM intoxication were also dose dependent. These changes, together with a significant reduction in the cellularity of the spleen and thymus and degenerative histological changes, show that a single sublethal dermal dose of SM can cause considerable dose dependent systemic effects in Balb/c mice.