Modification of Cytosolic Free Calcium Concentrations in Human Keratinocytes after Sulfur Mustard Exposure

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.

Antioxidant effect of genistein on ovarian tissue morphology, oxidant and antioxidant activity in rats with induced polycystic ovary syndrome

Background

Oxidative stress is the most frequent cause of female infertility disorders including polycystic ovary syndrome (PCOS). Genistein as a major component of soybean isoflavone scavenges free radicals by antioxidant activities.

Objective

The present study examines the antioxidant effects of genistein on ovarian tissue following experimental PCOS in rats.

Materials and Methods

Twenty female Wistar rat were randomly divided into the following groups (n=5 each group): (I) control group (no treatment); (II) induced PCOS (injection of estradiol valerate); (III) genistein-treated non-PCOS (received genistein); and (IV) genistein-treated PCOS groups. The weight of rats were measured and the blood samples collected and centrifuged. The oxidant and antioxidant activity of plasma and ovaries were measured. All rats were sacrificed under anesthesia, and ovaries were collected and weighted. Histological examination and follicular quality were assessed by staining.

Results

In histological observation, the induced PCOS rats displayed more number of atretic follicles and the follicular quality in genistein-treated rats was similar to the control groups. The plasma and ovaries malondialdehyde levels significantly increased in PCOS rats (p < 0.001), while the total antioxidant capacity levels, glutathione peroxidase, and superoxide dismutase activities significantly decreased (p < 0.001). The plasma and ovary malondialdehyde levels significantly decreased in PCOS rats that were treated with genistein (p < 0.001) and the total antioxidant capacity (p < 0.05), glutathione peroxidase, and superoxide dismutase activities significantly increased (p < 0.001).

Conclusion

Treatment with genistein preserved follicular quality by increasing antioxidant activities and scavenging oxidant levels in PCOS rats.

Transient Receptor Potential Channel A1 (TRPA1) Regulates Sulfur Mustard-Induced Expression of Heat Shock 70 kDa Protein 6 (HSPA6) In Vitro

The chemosensory transient receptor potential ankyrin 1 (TRPA1) ion channel perceives different sensory stimuli. It also interacts with reactive exogenous compounds including the chemical warfare agent sulfur mustard (SM). Activation of TRPA1 by SM results in elevation of intracellular calcium levels but the cellular consequences are not understood so far. In the present study we analyzed SM-induced and TRPA1-mediated effects in human TRPA1-overexpressing HEK cells (HEKA1) and human lung epithelial cells (A549) that endogenously exhibit TRPA1. The specific TRPA1 inhibitor AP18 was used to distinguish between SM-induced and TRPA1-mediated or TRPA1-independent effects. Cells were exposed to 600 µM SM and proteome changes were investigated 24 h afterwards by 2D gel electrophoresis. Protein spots with differential staining levels were analyzed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and nano liquid chromatography electrospray ionization tandem mass spectrometry. Results were verified by RT-qPCR experiments in both HEKA1 or A549 cells. Heat shock 70 kDa protein 6 (HSPA6) was identified as an SM-induced and TRPA1-mediated protein. AP18 pre-treatment diminished the up-regulation. RT-qPCR measurements verified these results and further revealed a time-dependent regulation. Our results demonstrate that SM-mediated activation of TRPA1 influences the protein expression and confirm the important role of TRPA1 ion channels in the molecular toxicology of SM.

Neuroprotective effect of Decalepis hamiltonii on cyclophosphamide-induced oxidative stress in the mouse brain

BACKGROUND

Cyclophosphamide (CP), one of the most widely used antineoplastic drugs, causes toxic side effects on vital organs including brain. In this study, we have investigated neuroprotective potential of the aqueous extract of the roots of Decalepis hamiltonii (DHA) against CP-induced oxidative stress in the mouse brain.

METHODS

Swiss albino male mice were pre-treated with DHA (50 and 100 mg/kg b.w.) for 10 consecutive days followed by an injection with CP intraperitoneally (25 mg/kg b.w.) for 10 days 1 h after DHA treatment; 16 h later, they were euthanized, their brains were immediately removed, and biochemical and molecular analyses were conducted.

RESULTS

The results indicated that injection of CP induced oxidative stress in the mouse brain as evident from the increased lipid peroxidation, reactive oxygen species, depletion of glutathione and reduced activities of the antioxidant enzymes such as superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase, and glutathione-S-transferase. Treatment with DHA significantly mitigated the CP-induced oxidative stress. Moreover, expression of genes for the antioxidant enzymes was downregulated by CP treatment which was reversed by DHA.

CONCLUSIONS

In conclusion, DHA protected the brain from oxidative stress induced by CP, and therefore, it could be a promising nutraceutical as a supplement in cancer chemotherapy in order to ameliorate the toxic side effects of cancer drugs.

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.

Amelioration of cyclophosphamide-induced hepatotoxicity by the root extract of Decalepis hamiltonii in mice

Hepatoprotective potential of the aqueous extract of the roots of Decalepis hamiltonii (DHA) against cyclophosphamide (CP)-induced oxidative stress has been investigated in mice. Administration of CP (25mg/kg b.w., i.p) for 10 days induced hepatic damage as indicated by the serum marker enzymes aspartate and alanine transaminases (AST, ALT), alkaline phosphatase (ALP) and lactate dehydrogenase (LDH). Parallel to these changes CP induced oxidative stress in the liver as evident from the increased lipid peroxidation (LPO), reactive oxygen species (ROS), depletion of glutathione (GSH), and reduced activities of the antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR), and glutathione-S-transferase (GST). Treatment with DHA (50 and 100 mg/kg b.w., po) mitigated the CP-induced oxidative stress. Moreover, expression of genes for the antioxidant enzymes, were down-regulated by CP treatment which was reversed by DHA. Our study shows the DHA protected the liver from toxicity induced by CP and therefore, it could be serve as a safe medicinal supplement during cyclophosphamide chemotherapy.

pH-dependent toxicity of sulphur mustard in vitro

The dependence of sulphur mustard (HD) toxicity on intracellular (pH(i)) and extracellular pH was examined in CHO-K1 cells. HD produced an immediate and significant concentration-dependent decline in cytosolic pH, and also inhibited the mechanisms responsible for restoring pH(i) to physiological values. The concentration-response of HD-induced cytosolic acidification, closely paralleled the acidification of the extracellular buffer through HD hydrolysis. A viability study was carried out in order to assess the importance of HD-induced cytosolic acidification. Cultures were exposed to HD for 1 h in media that were adjusted through a pH range (pH 5.0-10), and the 24 h LC(50) values were assessed using the viability indicator dye alamarBlue. The toxicity of HD was found to be dependent on extracellular pH, with a greater than eight-fold increase in LD(50) obtained in cultures treated with HD at pH 9.5, compared to those treated at pH 5.0. Assays of apoptotic cell death, including morphology, soluble DNA, caspase-3 activity and TUNEL also showed that as pH was increased, much greater HD concentrations were required to cause cell death. The modest decline in HD half-life measured in buffers of increasing pH, did not account for the protective effects of basic pH. The early event(s) that HD initiates to eventually culminate in cell death are not known. However, based on the data obtained in this study, we propose that HD causes an extracellular acidification through chemical hydrolysis and that this, in both a concentration and temporally related fashion, results in cytosolic acidification. Furthermore, HD also acts to poison the antiporter systems responsible for maintaining physiological pH(i), so that the cells are unable to recover from this insult. It is this irreversible decline in pH(i) that initiates the cascade of events that results in HD-induced cell death.

Dose- and time-dependent effects of sulfur mustard on antioxidant system in liver and brain of rat

This study investigates the dose- and time-dependent effects of sulfur mustard (SM) on antioxidant system and lipid peroxidation in liver and brain of rats. For this purpose, male Wistar rats were randomly divided into eight groups and treated as follows: group 1 as control and groups 2-8 as experimental groups that received SM (1-80 mg/kg) through intraperitoneal injection. Rats were killed after 2, 7 and 14 days of exposure. SM dose-dependently decreased body weight. Superoxide dismutase (SOD), catalase (CAT) and glutathione S-transferase (GST) activities in liver were significantly increased at SM doses lower than 10 mg/kg after 2 and 7 days of exposure. However, the recovery of these parameters was observed after 14 days. At these concentrations, no significant change in glutathione (GSH) and malondialdehyde (MDA) levels were observed. At doses higher than 10 mg/kg, SM significantly decreased SOD, CAT, glutathione peroxidase (GPX), and GST activities in liver and brain and decreased glutathione reductase (GR) activity in liver, which was associated with a depletion of GSH and increased MDA level. Present data indicate that the effect of SM is dose- and time-dependent and at higher doses (>10 mg/kg) induces an oxidative stress response by depleting the antioxidant defense systems and increasing lipid peroxidation in liver and brain of rats.

Effect of intracellular calcium modulation on sulfur mustard cytotoxicity in cultured human neonatal keratinocytes

Previous studies in human skin keratinocyte cultures have shown that sulfur mustard (HD) induces an immediate and irreversible increase in internal free calcium levels that was independent of external calcium concentrations. These findings suggested a role for calcium in the aetiology of HD-induced cell death and that modulation of intracellular calcium concentrations may assist in providing protection against this agent. In the current work, actively proliferating and confluent cultures of first passage neonatal human skin keratinocytes were used to assess the effect of altered intra- and extracellular calcium levels on HD toxicity. Treatment of cultures with the endoplasmic reticulum calcium ATPase inhibitor thapsigargin, or the calcium chelator BAPTA-AM, which reduce HD-induced elevation of intracellular free calcium, did not modulate the toxicity of HD. Furthermore, alteration of external calcium concentrations during these same experiments failed to elicit any change in the viability of HD-exposed cells. Treatment of confluent cultures with ionomycin at either low (100 microM) or high (1.2 mM) external calcium concentrations also failed to modulate the toxicity of HD in any way. It appears that in neonatal human skin keratinocytes in culture, HD-induced intracellular calcium perturbation does not play a major role in HD-induced cytotoxicity.

Synergistic protective effects of selected arginine analogues against sulphur mustard toxicity in neuron culture

Previous studies in this laboratory have shown that the arginine analogues L-thiocitrulline (L-TC) and L-nitroarginine methyl ester (L-NAME) have potent protective activity against sulphur mustard (HD) toxicity that was not related to their nitric oxide synthase inhibiting activities. Furthermore, their characteristics of action suggested that they act at different sites to exert their protection. L-TC acted rapidly (minutes of preincubation) and was equipotent in protecting either immature or mature cultures of chick embryo neurons against the toxicity of HD while L-NAME was only effective in mature cultures. Maximal protection occurred at mM drug concentrations and increased the LC50 of HD by approximately 200% (L-NAME) to approximately 800% (L-TC). L-NAME did not alter the efficacy of L-TC in immature cultures but increased the LC50 up to 1500% in mature cultures. Removal of L-NAME eliminated this synergism, leaving only the persistent protection of L-TC. L-Nitroarginine and d-NAME also increased the protective efficacy of L-TC in a concentration-related manner in mature cultures. The timing of drug administration before or after HD culture exposure was critical. Drug coadministration resulted in synergistic protection only when L-TC was added to the cultures prior to HD treatment. Thus, synergistic protective effects were also achieved when L-NAME was added up to 8 h after HD exposure, if they were pretreated with L-TC. Based on these findings, it is proposed that HD initiates its toxicity extremely rapidly through a cell surface-mediated event that can be blocked by L-TC. A signal is transduced into the cell that results in an additional event or lesion that manifests itself several hours downstream. This event/lesion progresses to cell death unless blocked reversibly by L-NAME.

l-thiocitrulline: A potent protective agent against the toxicity of sulphur mustard in vitro

Previous studies in this laboratory have shown that the well-characterized arginine analogue nitric oxide synthase (NOS) inhibitor, l-nitroarginine methyl ester (l-NAME) is protective against the cytotoxicity of the vesicating agent bis (2-chloroethyl) sulphide (HD). Furthermore, these protective effects were not mediated through the inhibition of NOS. In studies designed to investigate the efficacy of additional arginine analogue NOS inhibitors as protective agents against this compound, l-thiocitrullline (l-TC) was identified as being extremely potent. In contrast to the protection conferred by l-NAME, however, l-TC was found to protect immature cultures of neurons against HD, as well as mature cultures. In addition, l-TC was found to exert its effects prophylactically, as opposed to the therapeutic characteristics of l-NAME. l-TC gave approximately 800% protection against HD with a one-h pretreatment compared to approximately 1500% protection with a 24-h pretreatment. The protection conferred by l-TC against HD was persistent, and did not require the continued presence of l-TC after the initial HD lesion was expressed. The protective characteristics of l-TC against HD are very different than those of l-NAME and suggest that these closely related arginine analogues act at as yet unidentified and different sites to exert their effects.