Burn-induced Oxidative Stress Research Articles

Combination of sodium butyrate and probiotics ameliorates severe burn-induced intestinal injury by inhibiting oxidative stress and inflammatory response

Burns are a common traumatic injuries with considerable morbidity and mortality rates. Post-burn intestinal injuries are closely related to oxidative stress and inflammatory response. The aim of the current study was to investigate the combined effect of sodium butyrate (NaB) and probiotics (PROB) on severe burn-induced oxidative stress and inflammatory response and the underlying mechanism of action. Sprague-Dawley rats with severe burns were treated with NaB with or without PROB. Pathomorphology of skin and small intestine tissue was observed using hematoxylin and eosin staining and severe burn-induced apoptosis in small intestine tissue was examined via terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling assay. The release of factors related to inflammation was quantified using ELISA kits and qRT-PCR and levels of oxidative stress markers were evaluated using biochemical assays. Furthermore, mitochondrial morphological changes in small intestinal epithelial cells were observed using transmission electron microscopy. In addition, the underlying mechanism associated with the combined effect of NaB and PROB on severe burn-induced oxidative stress and inflammatory response was investigated using western blotting. The combination of NaB and PROB exerted protective effects against severe burn-induced intestinal barrier injury by reducing the levels of diamine oxidase and intestinal fatty acid binding protein. Combined NaB and PROB treatment inhibited severe burn-induced oxidative stress by increasing superoxide dismutase levels and decreasing those of malondialdehyde and myeloperoxidase levels. Severe burn-induced inflammation was suppressed by combined NaB and PROB administration, as demonstrated by the decreased mRNA expression of tumor necrosis factor-α, interleukin-6, interleukin-1β, and high mobility group box-1 in the small intestine. In addition, this study showed that combined NaB and PROB administration increased nuclear factor-erythroid 2-related factor 2 (Nrf2) protein expression and decreased the phosphorylation of nuclear factor (NF)-κB and extracellular signal-regulated kinase 1/2 (ERK 1/2). In conclusion, our findings indicate that combined NaB and PROB treatment may inhibit severe burn-induced inflammation and oxidative stress in the small intestine by regulating HMGB1/NF-κB and ERK1/2/Nrf2 signaling, thereby providing a new therapeutic strategy for intestinal injury induced by severe burn.

Prevention of Burn Wound Progression by Mesenchymal Stem Cell Transplantation: Deeper Insights Into Underlying Mechanisms.

Burns are dynamic wounds that may present a progressive expansion of necrosis into the initially viable zone of stasis. Therefore, salvage of this zone is a major subject of focus in burn research. The beneficial effects of mesenchymal stem cells (MSCs) on the survival of the zone of stasis have been previously documented. However, many gaps still exist in our knowledge regarding the underlying protective mechanisms. Hence, this study was designed to evaluate the pathophysiological basis of MSCs in the prevention of burn wound progression. Wistar rats received thermal trauma on the back according to the "comb burn" model. Animals were randomly divided into sham, control, and stem cell groups with sacrifice and analysis at 72 hours after the burn. The stasis zones were evaluated using histochemistry, immunohistochemistry, biochemistry, real-time polymerase chain reaction assay, and scintigraphy to evaluate the underlying mechanisms. Gross evaluation of burn wounds revealed that vital tissue percentage of the zone of stasis was significantly higher in the stem cell group. Semiquantitative grading of the histopathologic findings showed that MSCs alleviated burn-induced histomorphological alterations in the zone of stasis. According to CC3a staining and expression analysis of Bax (B-cell leukemia 2-associated X) and Bcl-2 (B-cell leukemia 2) genes, MSCs attenuated increases in apoptosis postburn. In addition, these transplants showed an immunomodulatory effect that involves reduced neutrophilic infiltration, down-regulation of proinflammatory cytokines (tumor necrosis factor α, interleukin 1β [IL-1β], and IL-6), and up-regulation of the anti-inflammatory cytokine IL-10 in the zone of stasis. Burn-induced oxidative stress was significantly relieved with MSCs, as shown by increased levels of malondialdehyde, whereas the expression and activity of the antioxidant enzyme superoxide dismutase were increased. Finally, MSC-treated interspaces had enhanced vascular density with higher expression levels for vascular endothelial growth factor A, platelet-derived growth factor, fibroblast growth factor, and transforming growth factor β. Gamma camera images documented better tissue perfusion in animals treated with MSCs. The protective effects of MSCs are mediated by the inhibition of apoptosis through immunomodulatory, antioxidative, and angiogenic actions.

Protective antioxidant effect of melanin against chemical burn-induced esophageal injury

Background: Oxidative stress is the main cause of mortality in chemical burn-induced esophageal injury. Melanin, a natural antioxidant compound from yeast-like fungus Nadsoniella nigra strain X- 1, has been shown to decrease the content of lipid peroxidation products after burn. The aim of this study was to investigate the protective effect of melanin in the treatment of esophageal injury after a chemical burn.
 Methods: A alkali burn model was used to induce injury to the esophagus in immature rats. Changes in the levels of malondialdehyde, secondary products of lipid peroxidation (thiobarbituric acid reactive substances), superoxidase dismutase, and catalase in the blood, as well as changes in the esophagus tissue, were examined.
 Results: Melanin decreased the content of lipid peroxidation products following burn injury. Melanin increased the activity of superoxidase dismutase and reduced the activity of catalase, as well as reduced esophagus oxidative injury in our chemical burn model.
 Conclusion: Melanin treatment may protect against chemical burninduced esophageal injury, possibly by inhibiting burn-induced oxidative stress.

Burn-induced Oxidative Stress and Serum Glutathione Depletion; a Cross Sectional Study.

Several studies have shown the role of oxidative stress in pathophysiology of burn injuries. This study aimed to evaluate the changes of oxidant-antioxidant levels during the week following burn injuries and its correlation with grade of burn. In this prospective cross-sectional study, changes of total glutathione, reduced glutathione (GSH), oxidized GSH (GSSG), GSH/GSSG ratio, as well as Pro-oxidant-antioxidant balance (PAB) were investigated on the 1st, 2nd and 7th days of admission in patients with > 15 % burns. 40 patients with the mean age of 21.1 ± 14.5 were studied (47.5% male). More than 50% of patients were in the 18 - 55 years age range and over 70% had 20% - 60% grade of burn. Total serum glutathione level and GSH had significant decreasing trends (P < 0.001) and GSSG and GSH/GSSG ratio had increasing trends (p < 0.001). No significant correlation was observed between serum GSH level and the total body surface area (TBSA) of burn injury (r = 0.047; p = 0.779). The evaluation of PAB and its correlation with TBSA showed a significant and direct association between them on the 1st (coefficient = 0.516; p = 0.001), 2nd (coefficient = 0.62; p <0.001), and 3rd (coefficient = 0.471; p = 0.002) day of follow up. According to this study, the redox perturbation occurred in burn injury which was measured and proved by decreased GSH/GSSG ratio as well as the shift of PAB in favour of oxidants. Besides, since PAB positively correlated with the severity of dermal damage, it might suggest the application of antioxidants as a part of therapeutic protocol for which the dosage should be proportionate to the surface area of the damaged skin.

Hepatoprotective effect of melatonin via activation of Nrf2 and anti-apoptotic proteins in burn rats

Abstract Objective: Burn- induced acute hepatic injury due to increased production of lipid peroxides and increased cellular apoptosis. The nuclear factor erythroid 2-related factor 2 (Nrf2) pathway is essential for cytoprotection against oxidative stress. We hypothesized that melatonin by activation of Nrf2 may shift Bax/Bcl-2 ratio to protect rat hepatocytes against apoptosis and progressive liver injury. The aim of this experimental study was to investigate the protective effects of melatonin against burn-induced apoptotic injury and the relationship between lipid peroxides expression of transcription factor Nrf2 and apoptotic protein in burn rat model. Methods: Melatonin was applied immediately after the burn. The expression of hepatic 4-hydroxynonenal (4-HNE), as a marker of liver peroxidative injury, Nrf2, as a marker of antioxidant defense and apoptosis-related genes Bcl-2 and Bax were evaluated using light immunоhistochemistry. Results: Burns caused an increased expression of 4-HNE, Bax and Bax/Bcl-2 ratio and induced apoptosis of sinusoidal endothelial cells (SECs) in liver tissue. Melatonin treatment augmented the increase in Nrf2 expression, decreased both burn-induced peroxidative damage and hepatic apoptosis as evidenced by reduced expression of Bax, enhanced expression of Bcl-2. In conclusion, our data suggest that activation of transcription factor Nrf2 by melatonin is protective against oxidative stress, apoptosis and hepatic injury in burns. The available information by melatonin`s effect on the redox sensing transcription factor Nrf2, as a regulator of antioxidant enzymes, antioxidants and antioxidant protection of the liver is limited. Melatonin activates the Nrf2/signaling pathway and acts as a natural inducer of anti-apoptotic and antioxidant protection under condition of burn-induced oxidative stress. This is a new cellular mechanism for protection against progressive burn-induced liver damage not only in animals but also in humans.

Protective effect of crocetin against burn-induced intestinal injury

BackgroundOxidative stress and inflammation exert central roles in burn-induced intestinal injury. Crocetin, a natural carotenoid compound from gardenia fruits and saffron, has been shown to inhibit oxidative stress and inflammatory response. However, the possibility of crocetin to be used in the treatment of intestinal injury after burn injury has not been investigated. The purpose of the present study was to investigate the effects and potential mechanisms of crocetin in burn-induced intestinal injury. Materials and methodsSeveral free radical–generating and lipid peroxidation models were used to systematically assess the antioxidant activities of crocetin in vitro. A common burn model was used to induce the intestinal injury in rats. Changes in the levels of malondialdehyde, superoxidase dismutase, catalase, glutathione peroxidase, tumor necrosis factor α, interleukin 6, polymorphonuclear neutrophil accumulation, intestinal permeability, and intestinal histology were examined. ResultsIn several models of antioxidant activity, crocetin exhibited marked inhibitory action against free radicals and lipid peroxidation. Crocetin increased levels of antioxidant enzymes and reduced intestinal oxidative injury in burn models. In addition, crocetin inhibited polymorphonuclear neutrophil accumulation, ameliorated tumor necrosis factor α and interleukin 6 levels, intestinal permeability, and histological changes. ConclusionsCrocetin treatment may protect against burn-induced small intestinal injury, possibly by inhibiting burn-induced oxidative stress and inflammatory response.

Protective effect of melatonin on myocardial injury in severely- burned rats

To investigate the protective effect of melatonin (MLT) on myocardial injury in severely-burned rats and its mechanism. A total of 30 Sprague-Dawley (SD) rats were randomly assigned to three groups: sham group, burn group and MLT group, each n=10. The dorsal skin of animal was immersed into boiling water for 15 seconds to induce 30% total body surface area (TBSA) full-thickness burn, or immersed into 37 centigrade water for sham operation. Immediately after burn, the animals in burn group and MLT group were given intraperitoneally vehicle (1% alcohol in normal saline) or MLT (10 mg/kg) respectively. Six hours postburn, the blood from tail vessel was collected for serum preparation. After sacrificed, the myocardial tissues of rats were collected for the determination of malondialdehyde (MDA) and reduced glutathione (GSH) as well as glutathione peroxidase (GSH-Px) and myeloperoxidase (MPO) activities. Serum levels of creatine kinase (CK) and lactate dehydrogenase (LDH) were also estimated. Compared with the sham control, burn injury increased MDA by 66.7% (1.55±0.17 nmol/mg vs. 0.93±0.05 nmol/mg) and decreased GSH by 27.8% (13.58±0.33 nmol/mg vs. 18.82±0.55 nmol/mg, both P<0.01) in myocardial tissues, GSH-Px activity was also slightly inhibited (74.04±3.42 nmol×min(-1)×mg(-1) vs. 93.79±3.76 nmol×min(-1)×mg(-1), P<0.05), but MPO level was found to increase to 2.8 folds (9.43±1.15 U/g vs. 3.41±0.27 U/g, P<0.01). These changes indicated the occurrence of oxidative stress in myocardial tissues after severe burn. MLT treatment relieved most of the abnormality with significant statistical significances (MDA: 0.89±0.08 nmol/mg vs. 1.55±0.17 nmol/mg, GSH: 17.23±0.54 nmol/mg vs. 13.58±0.33 nmol/mg, MPO: 6.91±0.51 U/g vs. 9.43±1.15 U/g, P<0.05 or P<0.01). In addition, the serum levels of CK and LDH in burn group increased to 37.8 folds and 7.4 folds respectively (both P<0.01). MLT treatment reduced CK by 32.9% and reduced LDH by 21.2% (P<0.05 and P<0.01). MLT treatment exerts the protective effect on myocardial injury in severely-burned rats, which is attributed predominantly to its inhibition on burn-induced oxidative stress injury.

Burn-induced Oxidative Stress is Altered by a Low Zinc Status: Kinetic Study in Burned Rats Fed a Low Zinc Diet

As an initial subdeficient status of zinc, considered as an essential antioxidant trace element, is frequent in burned patients, we aim to assess the effects of low zinc dietary intakes on burn-induced oxidative stress, in an animal model. After 8 weeks of conditioning diets containing 80 ppm (control group) or 10 ppm of zinc (depleted group), Wistar rats were 20% TBSA burned and sampled 1-10 days after injury. Kinetic evolutions of zinc status, plasma oxidative stress parameters, and antioxidant enzymes were also studied in blood and organs. The zinc-depleted diet induced, before injury, a significant decrease in zinc bone level and the increase of oxidative stress markers without stimulation of antioxidant enzyme activity. After burn, more markedly in zinc depleted animals than in controls, zinc levels decreased in plasma and bone, while increasing in liver. The decrease of thiol groups and GSH/GSSG ratio and the depression of GPx activity in liver are also moderately emphasized. Nevertheless, depleted zinc status could not be considered as determining for oxidative damages after burn injury. Further investigations must also be done to enlighten the mechanism of beneficial effects of zinc supplementation reported in burned patients.

Cardiac mitochondrial damage and loss of ROS defense after burn injury: the beneficial effects of antioxidant therapy.

Mechanisms of burn-related cardiac dysfunction may involve defects in mitochondria. This study determined 1) whether burn injury alters myocardial mitochondrial integrity and function; and 2) whether an antioxidant vitamin therapy prevented changes in cardiac mitochondrial function after burn. Sprague-Dawley rats were given a 3 degrees burn over 40% total body surface area and fluid resuscitated. Antioxidant vitamins or vehicle were given to sham and burn rats. Mitochondrial and cytosolic fractions were prepared from heart tissues at several times postburn. In mitochondria, lipid peroxidation was measured to assess oxidative stress, mitochondrial outer membrane damage and cytochrome-c translocation were determined to estimate mitochondrial integrity, and activities of SOD and glutathione peroxidase were examined to evaluate mitochondrial antioxidant defense. Cardiac function was measured by Langendorff model in sham and burn rats given either vitamins or vehicle. Twenty-four hours postburn, mitochondrial outer membrane damage was progressively increased to approximately 50%, and cytosolic cytochrome-c gradually accumulated to approximately three times more than that measured in shams, indicating impaired mitochondrial integrity. Maximal decrease of mitochondrial SOD activity occurred 8 h postburn ( approximately 63.5% of shams), whereas maximal decrease in glutathione peroxidase activity persisted 2-24 h postburn ( approximately 60% of shams). In burn animals, lipid peroxidation in cardiac mitochondria increased 30-50%, suggesting burn-induced oxidative stress. Antioxidant vitamin therapy prevented burn-related loss of membrane integrity and antioxidant defense in myocardial mitochondria and prevented cardiac dysfunction. These data suggest that burn-mediated mitochondrial dysfunction and loss of reactive oxygen species defense may play a role in postburn cardiac dysfunction.

Kinetic Changes of Oxidative Stress and Selenium Status in Plasma and Tissues following Burn Injury in Selenium-Deficient and Selenium-Supplemented Rats

This study investigates the relationship between the burn-induced oxidative stress and the selenium status. The rats were fed with a selenium-adequate diet or a selenium-depleted diet for 5 weeks, before a third-degree thermal injury was applied to the animals. One group of selenium-depleted animals received injections of sodium selenite after the injury. The selenium status and the oxidative stress parameters were measured for 5 days. The selenium-deficient diet leads to oxidative stress with a high stimulation of the superoxide dismutase activity. After the burn injury, the oxidative stress appears important because the initial selenium status is already impaired and, in all animals, the selenium levels and the antioxidant seleno-dependent glutathione peroxidase (GPx) activity decrease in the plasma and the tissues. A treatment with daily selenium injections is efficient in normalizing selenium levels and restores the GPx activity, but fails to counteract the initial oxidative damages induced by the selenium-deficient diet. The selenium status before the burn injury is a modulating factor of the burn-induced oxidative stress. A single selenium supplement is not sufficient to counteract these oxidative damages and henceforth combined antioxidant supplementations should be investigated to improve the early treatment of the burn patients.