Protective effect of trapidil against oxidative organ damage in burn injury

Kinetics of Inflammatory Mediators in the Immune Response to Burn Injury: Systematic Review and Meta-Analysis of Animal Studies

Burns are often accompanied by a dysfunctional immune response, which can lead to systemic inflammation, shock, and excessive scarring. The objective of this study was to provide insight into inflammatory pathways associated with burn-related complications. Because detailed information on the various inflammatory mediators is scattered over individual studies, we systematically reviewed animal experimental data for all reported inflammatory mediators. Meta-analyses of 352 studies revealed a strong increase in cytokines, chemokines, and growth factors, particularly 19 mediators in blood and 12 in burn tissue. Temporal kinetics showed long-lasting surges of proinflammatory cytokines in blood and burn tissue. Significant time-dependent effects were seen for IL-1β, IL-6, TGF-β1, and CCL2. The response of anti-inflammatory mediators was limited. Burn technique had a profound impact on systemic response levels. Large burn size and scalds further increased systemic, but not local inflammation. Animal characteristics greatly affected inflammation, for example, IL-1β, IL-6, and TNF-α levels were highest in young, male rats. Time-dependent effects and dissimilarities in response demonstrate the importance of appropriate study design. Collectively, this review presents a general overview of the burn-induced immune response exposing inflammatory pathways that could be targeted through immunotherapy for burn patients and provides guidance for experimental set-ups to advance burn research.

Inhalation injury and burn trauma: an experimental investigation of oxidative stress and histopathology

Smoke inhalation injury is associated with high incidence of pulmonary complications as it represents a major cause of mortality after major burn injury. Burn is associated with release of inflammatory mediators which ultimately cause local and distant pathophysiological effects. The present study investigated the effect of smoke inhalation or\and burn injury on the antioxidants status in the lungs in a rat model to simulate an inhalation injury as might be encountered by firefighters and burn victims. Seventy five rats were equally randomized to five groups: Sham group, smoke inhalation injury group, burn group, sham burn group, and smoke burn group. At the end of the exposure protocol rats were killed by cervical decapitation and the lungs were removed completely and processed for histopathological and biochemical analysis by measuring lung antioxidant enzyme activities: Malondialdehyde (MDA), superoxide dismutase (SOD) and glutathione peroxidase (GPs) level, as an index of lipid peroxidation. Grossly, results showed that rats´lungs in the smoke inhalation group and the smoke burn group showed multiple hemorrhagic spots. Light microscopic examination showed localized and diffuse alveolar hemorrhage. Two rats in the burn group had evidence of pneumonia and lung abscesses. Biochemically, results showed that both smoke inhalation and burn injury significantly elevated lung MDA and glutathione peroxidase levels when compared with controls. The combined smoke and burn group resulted in a more significant rise in both antioxidant levels indicating a higher level of lipid peroxidation. SOD level was significantly lowered on exposure to both conditions when compared to control. SOD level was significantly lower in the combined injury group when compared to either smoke or burn alone. In conclusion; the above data provide evidence that inhalation injury with and without burn decrease tissue antioxidant capacity and increase tissue peroxidative injury.

Markers of oxidative stress after ablation of atrial fibrillation are associated with inflammation, delivered radiofrequency energy and early recurrence of atrial fibrillation

BACKGROUND

The role of oxidative stress after radiofrequency ablation of atrial fibrillation (AF) has not yet been well characterized. We sought to evaluate the time course of biomarkers of oxidative stress and inflammation after AF ablation and their association with clinical variables.

METHODS

Thirty consecutive patients (57.9 ± 1.7 years, 63% males) with paroxysmal AF underwent pulmonary vein isolation and ablation of complex fractionated atrial electrograms. Biomarkers were determined in blood samples before ablation and 6 h, 1, 2, 7, 30, 90 and 180 days post-ablation.

RESULTS

The pro-oxidant enzyme myeloperoxidase and oxidized low-density lipoprotein reflecting oxidant damage of lipoproteins increased 2.9 ± 0.2-fold and 1.2 ± 0.1-fold, respectively, and were significantly up-regulated until day 2 post-ablation. The anti-oxidant enzyme copper/zinc superoxide dismutase did not change significantly. Inflammatory markers significantly increased (high-sensitivity C-reactive protein (hs-CRP): 41 ± 8-fold; interleukin-6: 4.4 ± 0.7-fold) for 7 and 2 days, respectively. The increase of myeloperoxidase and hs-CRP was interrelated and both predicted early recurrence of AF within the first post-ablation week (both p < 0.05). The increase of both markers was associated with the amount of delivered radiofrequency energy (p < 0.05). The up-regulation of hs-CRP correlated with troponin T (p = 0.008), while myeloperoxidase and troponin T were borderline associated (p = 0.054). However, the oxidative and inflammatory responses did not predict long-term ablation outcome (p > 0.05).

CONCLUSIONS

Markers of oxidative stress showed a significant up-regulation during the first 2 days after AF ablation. Their up-regulation was linked to inflammation, delivered radiofrequency energy, and early recurrence of AF, but did not predict long-term ablation outcome.

Remote thermal injury increases LPS-induced intestinal IL-6 production

BACKGROUND

Patients suffering from burn injury are at high risk for subsequent infection. Thermal injury followed by endotoxemia may result in a "second hit," causing an exaggerated inflammatory response with increased morbidity and mortality. The role of the intestine in this "second hit" response is unknown. We hypothesized that remote thermal injury increases the inflammatory response of intestinal mucosa to subsequent treatment with lipopolysaccharide (LPS).

METHODS

Mice underwent sham or scald injury. Seven days after injury, mice were treated with LPS. Blood and bowel specimens were obtained. Serum and intestinal inflammatory cytokines were measured by enzyme-linked immunosorbent assay (ELISA). Changes in TLR-4 pathway components in intestine were measured by reverse transcription-polymerase chain reaction (RT-PCR), Western blot, and electrophoretic mobility shift assay (EMSA). Intestinal leukocyte infiltration was analyzed by myeloperoxidase assay.

RESULTS

A "second hit" of injected LPS resulted in increased IL-6 in intestine of burned mice compared with sham. Similarly, jejunal IL-6 mRNA levels increased in mice with prior thermal injury, suggesting a transcriptional mechanism. Of transcription factors known to drive IL-6 expression, only AP-1 activation was significantly elevated by a "second hit" of LPS.

CONCLUSION

Prior thermal injury potentiates LPS-induced IL-6 cytokine production in intestine. These results indicate a heightened inflammatory response to a second hit by intestine after burn injury.

The role of trapidil on neuronal apoptosis in neonatal rat model of hypoxic ischemic brain injury

BACKGROUND

Hypoxic ischemic brain injury (HIBI) is a common cause of neonatal mortality and morbidity. Trapidil is an antiplatelet agent and several studies demonstrate the beneficial effect of trapidil in various forms of tissue injury. The effects of trapidil on neuronal apoptosis in HIBI have not been reported previously.

AIMS

The aim of this study is to evaluate the effect of trapidil on neuronal apoptosis in neonatal rat model of HIBI.

STUDY DESIGN

Seven-day-old Wistar rat pups were subjected to right common carotid artery ligation and hypoxia (92% nitrogen and 8% oxygen) for 2h. They were treated with trapidil or saline either immediately before or after hypoxia. In sham group animals, neither ligation, nor hypoxia were performed. Neuronal apoptosis was evaluated by the terminal deoxynucleotidyltransferase-mediated dUTP nick-end labeling (TUNEL) and caspase-3 staining methods.

RESULTS

Trapidil treatment either before or after hypoxia results in significant reduction of the numbers of apoptotic cells in both hemispheres, when it is compared with saline treatment group. The numbers of apoptotic cells in right hemispheres in all groups are significantly higher than that in the left hemispheres.

CONCLUSIONS

These results show that trapidil administration either before or after hypoxia reduces neuronal apoptosis and we propose that trapidil may be a novel approach for the therapy of HIBI.

Oxidative stress-induced leaky sarcoplasmic reticulum underlying acute heart failure in severe burn trauma

Burn trauma causes cardiac dysfunction. However, much of the underlying cellular and molecular mechanisms remain elusive. In the present study, we demonstrate the roles of excessive sarcoplasmic reticulum (SR) Ca(2+) leakage and oxidative stress in burn-associated acute heart failure. In cardiomyocytes from failing rat hearts 12 h after full-thickness cutaneous burn of about 40% of the total body surface area, we found that Ca(2+) transients and contractility were impaired, but the triggering L-type Ca(2+) channel current density was unaltered, giving rise to a significantly reduced gain of excitation-contraction coupling. This deficiency in SR Ca(2+) release was accompanied by a reduction in Ca(2+) content in the SR. Surprisingly, the frequency of spontaneous Ca(2+) sparks was increased by 1.4-fold; Ca(2+) tolerance test (10 mM extracellular Ca(2+)) further showed 2.0- and 1.5-fold more frequent Ca(2+) waves and Ca(2+) sparks, respectively. Myofilament sensitivity to Ca(2+), however, seemed to be unaffected. These results suggest hyperactivity of the ryanodine receptor (RyR) Ca(2+) release channel and a leaky SR in burn. Importantly, pretreatment with antioxidant vitamins C and E seemed to prevent burn-induced RyR hypersensitivity and SR leakage and thereby normalize Ca(2+) transients and contractility. Concomitantly, the in vivo cardiac functions were also more tolerant of traumatic burn. Collectively, our findings suggest that SR leakage due to oxidative stress is likely a major candidate mechanism underlying burn-associated acute heart failure. Antioxidant therapy in burn trauma provides cardioprotection, at least in part, by protecting RyR's from oxidative stress-induced hypersensitivity.