A preliminary exploration of the relationship between tumour necrosis factor (TNF) and monocytic in vitro production of interleukin-1 (IL-1) and internal organ dysfunction in severely burned patients

Hepatic functional pathophysiology and morphological damage following severe burns: a systematic review and meta-analysis

INTRODUCTION

Severe burns are devastating injuries affecting multiple organ systems. Little is known about the influence on the hepatic system and its physiology. This systematic review aimed to assess the current state of research on morphologic liver damage following severe burns.

METHODS

A search was conducted in Pubmed, Web of Science and Cochrane databases using PRISMA guidelines. Outcomes included serum levels of transaminases, fatty infiltration and necrosis. Weighted individual study estimates were used to calculate pooled transaminase levels and necrosis/fatty infiltration rates using a random-effects approach. Risk ratios (RRs) or Odds ratios (ORs) and 95% confidence intervals (CIs) were used to describe pooled estimates for risk factors.

RESULTS

The literature search retrieved 2548 hits, of which 59 studies were included into qualitative synthesis, and finally ten studies were included into meta-analysis. Studies were divided into those reporting autopsies and those reporting changes of serum transaminase levels. The majority of liver autopsies showed fatty infiltration 82% (95% CI39%-97%) or necrosis of the liver 18% (95% CI13%-24%).

DISCUSSION

Heterogeneity in studies on hepatic functional damage following severe burns was high. Only few were well-designed and published in recent years. Many studies could not be included because of insufficient numerical data. There is a high number of patients deceasing from burns that present with fatty infiltration or necrosis of hepatic tissue. Transaminases were elevated during the first days after burn. Further research on how severe burns affect the hepatic function and outcome, especially long-term, is necessary.

Cardiac Dysfunction in Severely Burned Patients: Current Understanding of Etiology, Pathophysiology, and Treatment

Patients who experience severe burn injuries face a massive inflammatory response resulting in hemodynamic and cardiovascular complications. Even after immediate and appropriate resuscitation, removal of burn eschar and covering of open areas, burn patients remain at high risk for serious morbidity and mortality. As a result of the massive fluid shifts following the initial injury, along with large volume fluid resuscitation, the cardiovascular system is critically affected. Further, increased inflammation, catecholamine surge, and hypermetabolic syndrome impact cardiac dysfunction, which worsens outcomes of burn patients. This review aimed to summarize the current knowledge about the effect of burns on the cardiovascular system.A comprehensive search of the PubMed and Embase databases and manual review of articles involving effects of burns on the cardiovascular system was conducted.Many burn units use multimodal monitors (e.g., transpulmonary thermodilution) to assess hemodynamics and optimize cardiovascular function. Echocardiography is often used for additional evaluations of hemodynamically unstable patients to assess systolic and diastolic function. Due to its noninvasive character, echocardiography can be repeated easily, which allows us to follow patients longitudinally.The use of anabolic and anticatabolic agents has been shown to be beneficial for short- and long-term outcomes of burn survivors. Administration of propranolol (non-selective β-receptor antagonist) or oxandrolone (synthetic testosterone) for up to 12 months post-burn counteracts hypermetabolism during hospital stay and improves cardiac function.A comprehensive understanding of how burns lead to cardiac dysfunction and new therapeutic options could contribute to better outcomes in this patient population.

Evaluation of the Treatment Effect of Aloe vera Fermentation in Burn Injury Healing Using a Rat Model

Burn injury is a growing medical problem associated with public health, and few effective agents are available for treatment of this disease. In the present study, a burn injury rat model was developed and the accelerated effect of Aloe vera fermentation on burn injury healing was evaluated. Our results indicated that Aloe vera fermentation could markedly reduce the DPPH (56.12%), O^2·− (93.5%), ^·OH (76.12%), Fe²⁺ chelation (82%), and oxygen-reduction activity (0.28 μg/ml) and significantly inhibited the growth of pathogens S. typhimurium ATCC 13311 (inhibition zone diameter: 14 mm), S. enteritidis ATCC13076 (IZD: 13 mm), S. flexneri ATCC 12022 (IZD: 18 mm), E. coli 44102 (IZD: 10 mm), L. monocytogenes ATCC 19111 (IZD: 18 mm), S. dysenteriae 301 (IZD: 20 mm), S. aureus COWAN1 (IZD: 19 mm), and P. acnes ATCC 11827 (IZD: 25 mm) in vitro. The in vivo results indicated that Aloe vera fermentation produced more eosinophils and fibroblasts and less vessel proliferation compared with the model group on the 14^th day, which had greatly accelerated burn injury healing via shedding of the scab and promoting hair growth. ELISA results indicated that Aloe vera fermentation had significantly reduced the production of proinflammatory factors TNF-α and IL-1β (p < 0.05) and greatly enhanced the yield of anti-inflammatory factor IL-4 in animal serum (p < 0.05). In addition, the high-throughput sequencing results indicated that Aloe vera fermentation obviously increased the percentage of Firmicutes (65.86% vs. 49.76%), while reducing the number of Bacteroidetes (27.60% vs. 45.15%) compared with the M group at the phylum level. At the genus level, Aloe vera fermentation increased the probiotic bacteria Lactobacillus (3.13% vs. 2.09%) and reduced the pathogens Prevotella (10.60% vs.18.24%) and Blautia (2.91% vs. 16.41%) compared with the M group. Therefore, we concluded that the use of Aloe vera fermentation significantly accelerates burn injury healing via reduction of the severity of inflammation and through modification of gut microbiota.

Inhibition of p38 MAP kinase improves survival of cardiac myocytes with hypoxia and burn serum challenge

This study was aimed to investigate the effects of SB203580, the specific p38 mitogen-activated protein (MAP) kinase inhibitor, on cardiac myocyte survival and secretion of cytokines in an in vitro model of hypoxia and burn serum challenge. Results demonstrated that hypoxia and burn serum induced a persistent activation of p38 MAP kinase in primary cultured neonatal rat cardiomyocytes during the 12h period of stimulation, concomitant with a time-dependent increased expression of tumor necrosis factor (TNF)-alpha and inducible nitric oxide (iNOS), a progressively developed oxidative stress reflected by malondialdehyde (MDA) production, and myocytes injury evidenced by the increased levels of released lactate dehydrogenase (LDH) and the decreased myocyte viability. Furthermore, hypoxia and burn serum resulted in a significant increase in myocyte apoptosis, which may account for the impairment of myocyte viability as observed. SB203580 abolished p38 MAP kinase activation, blunted the upregulation of TNF-alpha, iNOS and the subsequent nitric oxide (NO) production, reduced oxidative stress, and alleviated hypoxia and burn serum-induced myocytes injury or apoptosis. These results demonstrated for the first time that inhibition of p38 MAP kinase improves survival of cardiac myocytes with hypoxia and burn serum challenge possibly via reducing the production of cytokines, such as TNF-alpha and NO, and the subsequent oxidative stress, providing strong evidence that the excessive inflammatory cytokines produced by cardiomyocytes themselves may be sufficient to cause myocardial injury after burn.

Preconditioning: Gender Effects1

Preconditioning is injury induced protection from subsequent injury. During preconditioning protective cellular responses to injury are up regulated resulting in acute and delayed defense against further damage. Several studies indicate that females experience a protective advantage after acute insult compared to males. Despite evidence of gender differences in acute injury, relatively few studies have evaluated whether there are sex differences in preconditioning. Variations in patients' pre-morbid preconditioning status may explain outcome variations that are not apparent in small animal studies. This review discusses the differences in response to acute injury experienced by males and females, the basic mechanisms of preconditioning, and the sex differences in the mechanisms of preconditioning.

Antioxidant vitamin therapy alters burn trauma-mediated cardiac NF-kappaB activation and cardiomyocyte cytokine secretion

BACKGROUND

This study examined the effects of antioxidant vitamins A, C, and E on nuclear transcription factor-kappa B (NF-kappaB) nuclear translocation, on secretion of inflammatory cytokines by cardiac myocytes, and on cardiac function after major burn trauma.

METHODS

Adult rats were divided into four experimental groups: group I, shams; group II, shams given oral antioxidant vitamins (vitamin C, 38 mg/kg; vitamin E, 27 U/kg; vitamin A, 41 U/kg 24 hours before and immediately after burn); group III, burns (third-degree scald burn over 40% total body surface area) given lactated Ringer's solution (4 mL/kg/% burn); and group IV, burns given lactated Ringer's solution plus vitamins as described above. Hearts were collected 4, 8, 12, and 24 hours after burn to assay for NF-kappaB nuclear translocation, and hearts collected 24 hours after burn were examined for cardiac contractile function or tumor necrosis factor-alpha secretion by cardiomyocytes.

RESULTS

Compared with shams, left ventricular pressure was lower in burns given lactated Ringer's solution (group III) (88 +/- 3 vs. 64 +/- 5 mm Hg, p < 0.01) as was +dP/dt max (2,190 +/- 30 vs. 1,321 +/- 122 mm Hg/s) and -dP/dt max (1,775 +/- 71 vs. 999 +/- 96 mm Hg, p < 0.01). Burn injury in the absence of vitamin therapy (group III) produced cardiac NF-kappaB nuclear migration 4 hours after burn and cardiomyocyte secretion of tumor necrosis factor-alpha, interleukin-1beta, and interleukin-6 by 24 hours after burn. Antioxidant therapy in burns (group IV) improved cardiac function, producing left ventricular pressure and +/-dP/dt (82 +/- 2 mm Hg, 1,880 +/- 44 mm Hg, and 1,570 +/- 46 mm Hg/s) comparable to those measured in shams. Antioxidant vitamins in burns inhibited NF-kappaB nuclear migration at all times after burn and reduced burn-mediated cytokine secretion by cardiomyocytes.

CONCLUSION

These data suggest that antioxidant vitamin therapy in burn trauma provides cardioprotection, at least in part, by inhibiting translocation of the transcription factor NF-kappaB and interrupting cardiac inflammatory cytokine secretion.

Protective effect of early enteral feeding on postburn impairment of liver function and its mechanism in rats

AIM: To study the protective effect of early enteral feeding (EEF) on the postburn impairment of liver function and its mechanism.

METHODS: Wistar rats with 30% of total body surface area (TBSA) full-thickness burn were employed. The effects of EEF on the postburn changes of gastric intramucosal pH, endotoxin levels in portal vein, water contents of hepatic tissue, blood concentrations of tumor necrosis factor (TNF-α), plasma activities of alanine aminotransferase (ALT) and asparate amin otransferase (AST), as well as the blood contents of total (TB) and direct bilirubin (DB), total protein (TP) and albumin (ALB) were serially determined within 48 h postburn.

RESULTS: EEF could significantly improve gastric mucosalacidos is, reduce portal vein endotoxin level and water content of hepatic tissue, as w ell as plasma concentrations of TNF-α at all timepoints after seve re burns (P < 0.01); postburn elevation of the plasma activities of ALT, AST and the contents of TB, DB were effectively prevented, whereas the plasma conce ntrations of TP and ALB were markedly increased 24 h and 48 h posturn in EEF group compared with that of the burn without EEF group (P < 0.01).

CONCLUSION: EEF has significant beneficial effects on the impro vement of hepatic function in rats after severe burn, and is probably related with an increase in splanchnic blood flow, reduction of the absorption of gut-origin endotoxin and the consequent release of inflammatory mediators.

The effect of severe burn injury on proinflammatory cytokines and leukocyte behavior: its modulation with granulocyte colony-stimulating factor

Severe injury causes immunosuppression. The main contributors are impaired leukocyte function and a cytokine dysbalance. GCSF increases PMN count, function and modulates the inflammatory response. However GCSF may overactivate leukocytes. The purpose of this study is to investigate whether GCSF is able to restore immune competence after severe injury. Lewis rats were divided into three groups: 30% TBSA burn + vehicle; 30% TBSA burn + GCSF (150 microg rhGCSF); Control. Blood samples were taken for total white cell count, PMNs, TNFalpha and IFNgamma. Leukocyte rolling and sticking were measured in the cremaster muscle microcirculation. Leukocyte diapedesis was investigated by lavage of the abdominal cavity and the lungs. Total white cell and PMN counts in the burn + GCSF group were significantly higher (P<0.001) than in burn+vehicle animals. Leukocyte adherence and diapedesis were not elevated in the burn + GCSF group as compared to the burn + vehicle group. TNFalpha (P<0.05) and IFNgamma (P<0.001) levels were significantly increased in the burn + vehicle animals compared to the burn + GCSF animals. GCSF modifies the immune system, as shown by an increase in white cell and PMN counts and by balancing the overall immune response from proinflammatory to normal, as shown by decreased TNFalpha and IFNgamma levels. GCSF does not overactivate PMNs.

Pathogenesis of early cardiac myocyte damage after severe burns

BACKGROUND

The importance of early cardiac myocyte damage during postburn trauma has been emphasized in recent years. However, its pathogenesis, prevention, and treatment have not been fully clarified. The aim of this study is to define its pathogenesis.

METHODS

Rats with 30% third-degree burns were used. Cardiac biochemical markers reflecting cardiac myocyte damage including troponin T, cardiac myosin light chain 1, creatinine kinase and its cardiac-specific isoenzyme compound, as well as inflammatory mediators such as tumor necrosis factor, endothelin/nitric oxide ratio, malondialdehyde, and superoxide dismutase, were determined.

RESULTS

Cardiac biochemical markers reflecting cardiac myocyte damage, including troponin T, cardiac myosin light chain 1, cardiac-specific isoenzyme compound, were all significantly elevated between 3 hours and 24 hours after burn. Changes in tumor necrosis factor, endothelin/nitric oxide ratio, and malondialdehyde were similar to those of cardiac biochemical markers. In contrast, levels of superoxide dismutase declined markedly after burn.

CONCLUSION

The findings of this study showed that considerable amounts of myocardial constructive protein degradation and release due to destruction of cardiac myocytes occurred early after severe burns. The inflammatory mediators released after burn injury may be involved in the pathogenesis of myocardial destruction.

Plasma tumor necrosis factor-alpha, its soluble receptors and interleukin-1beta levels in critically burned patients

Levels of plasma TNF-alpha, interleukin-1beta(IL-1beta ), soluble TNF-receptor I (sTNF-R I) and soluble TNF-receptor II (sTNF-R II) were determined in 16 critically burned patients. Seven of the 16 patients showed hypovolemic shock (shock group), 9 with sepsis (sepsis group), 8 with multiple organ dysfunction syndrome (MODS group) and 6 of them died (non-survival group). Plasma TNF-alpha, sTNF-R I and R II were significantly higher in the shock group, the MODS group and the non-survival group than each of the control groups. TNF-alpha and sTNF-Rs increased gradually in the MODS group and the non-survival group from 1 to 5 days postburn. TNF-alpha, sTNF-R I and R II correlated positively with Goris' multiple organ failure score. Molecular sTNF-Rs/TNF-alpha ratios were lower in the sepsis group than in the non-sepsis group. These results suggest that circulating TNF and soluble TNF receptors system play an important role in the development of burn shock and MODS; high molecular ratios of endogenous sTNF-Rs might not reduce the morbidity of MODS and the mortality in critically burned patients.

Aspiration pneumonia-induced sepsis increases cardiac dysfunction after burn trauma

Pneumonia occurs in approximately 50% of incubated patients in burn intensive care units and carries a mortality as high as 40%. A model was developed to study altered cardiopulmonary function in burn complicated by pneumococcal pneumonia. Sprague-Dawley rats were given a 43% total body surface area scald burn or sham burn; 24 h later they were transtracheally inoculated with either 10(7) Streptococcus pneumoniae in 0.5 ml phosphate buffer solution (PBS) or 0.5 ml PBS alone. The four groups were: Sham (N = 7), Burn alone (N = 10), Pneumonia alone (N = 11), and Burn and Pneumonia ( N = 12). A fifth group of burned rats (N = 10), given an identical fluid resuscitation regimen, was sacrificed 24 h postburn to examine the early cardiac responses to burn injury alone. Shams and burned animals had normal lung histology, negative bronchoalveolar lavage (BAL) cultures, and negative blood cultures. Pneumonia and burn plus pneumonia animals had abnormal lung histology, positive BAL cultures, and positive blood cultures. Cardiac function was assessed 24 h after S.pneumoniae challenge (48 h after burn) (Langendorff preparation). Compared to the Sham group, Pneumonia group, and Burn group, the Burn plus Pneumonia group had the lowest left ventricular pressure (LVP: 94 +/- 4, 71 +/- 3, and 87 +/- 3 mm Hg vs 63 +/- 4 mm Hg, P < 0.05), the lowest maximal rate of LVP rise (+dP/dt[max]:1932 +/- 115, 1419 +/- 71, and 1772 +/- 96 mm Hg vs 1309 +/- 59 mm Hg/s, P < 0.05), and the lowest maximal rate of LVP fall (-dP/dt[max]:1704 +/- 120, 1263 +/- 73, and 1591 +/- 83 mm Hg vs 1025 +/- 98 mm Hg/s, P < 0.05). Cardiac contraction and relaxation deficits were confirmed in animals 24 h postburn (group 5), as indicated by a significantly lower LVP and +/-dP/dt(max) (62 +/- 3 mm Hg 1210 +/- 60, and 909 +/- 50 mm Hg/s, respectively, P < 0.05 compared to Sham group). Tumor necrosis factor-alpha (TNF-alpha) concentrations in serum, but not bronchoalveolar lavage, were greater in burned animals with aspiration pneumonia-induced sepsis than in animals with either burn alone or aspiration pneumonia-induced sepsis alone. While our data suggest that elevated circulating TNF-alpha levels may contribute, in part, to depressed cardiac function, further studies are needed to fully define the mechanisms underlying cardiac contractile deficits in this model. We speculate that depressed cardiopulmonary function due to burn complicated by pneumonia and sepsis contributes to the high mortality of this patient population.

Changes in serum tumour necrosis factor-alpha in burned patients

Dynamic tumour necrosis factor-alpha (TNF-alpha) changes in serial serum samples of 10 burned patients were analysed in this study. The total body surface areas (TBSA) of the burn injury were from 30 to 85 per cent. Among these 10 patients, five recovered and another five died with proved sepsis. On admission which was about 5-13 h postburn, eight of the 10 patients showed their serum TNF-alpha levels to be higher than the mean serum TNF-alpha value of five healthy laboratory personnel. Furthermore, an initial peak serum TNF-alpha response which could be detected within 2.5 days after burn injury has also been observed. However, significant differences in both the serum TNF-alpha values on admission, as well as the first peak serum TNF-alpha levels, were not found (P > 0.05) between patients with TBSA of greater or less than 50 per cent and patients who survived or died from burn injury. In the survivors, serum TNF-alpha stayed at low levels, while it increased markedly in four of the five non-survivors with proven sepsis starting at about 1 week postburn. A significant difference in the maximum serum TNF-alpha levels (P < 0.05) was detected between patients who recovered and died from the thermal injury. In conclusion, great increases in serum TNF-alpha levels have been detected in burned patients with the occurrence of bacterial infection postburn. It is suggested that strategies for the inhibition of TNF-alpha production or in the neutralization of TNF-alpha activity should also be considered in the better treatment of burned patients.

Pathophysiology of the burn wound and pharmacological treatment. The Rudi Hermans Lecture, 1995

The body's reaction to thermal injury is much more than an initial, local inflammatory response. The burn wound is a continuous, severe threat against the rest of the body due to invasion of infectious agents, antigen challenge and repeated additional trauma caused by wound cleaning and excision. The inflammatory mediators which control blood supply and microvascular permeability in the wound have been extensively studied and are largely understood. Attempts to suppress the inflammatory reaction by different drugs, have, however, been less successful. Extensive thermal injury and sepsis also results in immunosuppression. The defects causing immunosuppression are still very much under consideration. An understanding of these defects is essential for the development of therapies. The increasing interest in the control of the inflammatory reactions by cytokines may, in the near future, be of great importance.