Current Status Of Burn Wound Pathophysiology

Morphine concentrations in fatalities after palliative treatment of acute burn injury

The evaluation of a morphine concentration in postmortem blood is routine for a forensic toxicologist. We here report three fatal cases where we found high morphine concentrations with 7.96, 4.30, and 5.82 mg/l in femoral blood that have to be estimated as unusually high. All these individuals died due to severe burn injuries and obtained morphine in the context of their palliative care in the last hours of their lives. According to the autopsy results, the cause of death in case 1 was burn disease with burns of about 90% of the body surface area (BSA), case 2 burn trauma, and case 3 burn shock. Besides morphine, propofol, fentanyl, sufentanil, midazolam, diazepam, lorazepam, cefazolin, and rocuronium were detected in femoral blood. The findings fitted well with the detailed clinical documentation. Further evidence of therapeutic concentrations of quetiapine, duloxetine, and melperone could be matched to preexisting medication of the individuals. Physiologically based pharmacokinetic modelling (PBPK) was applied, developed for the intravenous administration of morphine, to find an explanation for the high morphine concentrations in femoral blood. Quantification of morphine in body fluids and tissue was performed to calculate morphine tissue concentration ratios to the morphine concentration in femoral blood. The presented cases show that pharmacokinetic simulations can reflect decreased renal clearance and decreased hepatic metabolism in general. However, this prediction is not sufficient to explain the high morphine concentrations in femoral blood measured here. It can be assumed that burn shock in particular leads to altered pharmacokinetics, namely decreased distribution of morphine.

Accelerated burn wound healing with photobiomodulation therapy involves activation of endogenous latent TGF-β1

The severity of tissue injury in burn wounds from associated inflammatory and immune sequelae presents a significant clinical management challenge. Among various biophysical wound management approaches, low dose biophotonics treatments, termed Photobiomodulation (PBM) therapy, has gained recent attention. One of the PBM molecular mechanisms of PBM treatments involves photoactivation of latent TGF-β1 that is capable of promoting tissue healing and regeneration. This work examined the efficacy of PBM treatments in a full-thickness burn wound healing in C57BL/6 mice. We first optimized the PBM protocol by monitoring tissue surface temperature and histology. We noted this dynamic irradiance surface temperature-monitored PBM protocol improved burn wound healing in mice with elevated TGF-β signaling (phospho-Smad2) and reduced inflammation-associated gene expression. Next, we investigated the roles of individual cell types involved in burn wound healing following PBM treatments and noted discrete effects on epithelieum, fibroblasts, and macrophage functions. These responses appear to be mediated via both TGF-β dependent and independent signaling pathways. Finally, to investigate specific contributions of TGF-β1 signaling in these PBM-burn wound healing, we utilized a chimeric TGF-β1/β3 knock-in (TGF-β1^Lβ3/Lβ3) mice. PBM treatments failed to activate the chimeric TGF-β1^Lβ3/Lβ3 complex and failed to improve burn wound healing in these mice. These results suggest activation of endogenous latent TGF-β1 following PBM treatments plays a key role in burn wound healing. These mechanistic insights can improve the safety and efficacy of clinical translation of PBM treatments for tissue healing and regeneration.

C1 Esterase Inhibitor Activity Is Reduced in the Acute Phase Following Burn Injury: A Prospective Observational Study

Hereditary angioedema has been attributed to an inherited deficiency of C1 esterase inhibitor that increases vascular permeability. The role of C1 esterase inhibitor in burn patients has not been described previously. In this study, we attempted to identify the relationship between serial changes of C1 esterase inhibitor activity and the clinical course in major burn patients. This study was a single-center, prospective, observational study. C1 esterase inhibitor activity values were serially examined in major burn patients admitted into the burn center from April 2014 to December 2016. Inclusion criteria were age ≥16 years old and %TBSA burned ≥20%. This study included 38 patients with major burn. C1 esterase inhibitor activity after burn dropped acutely on days 1 and 2 but increased immediately until days 3 to 5, after which it continued to gradually increase to above the reference value. C1 esterase inhibitor activity on admission showed significant inverse correlation with the volume of infusion per body weight required in the first 24 hours after injury and %TBSA burned (r = -0.405, P = 0.01; r = -0.375, P = 0.02, respectively). C1 esterase inhibitor activity on admission was significantly lower in the nonsurvivors than in the survivors during the 28-day evaluation period (59% vs 90%, P = 0.01). These findings suggest that C1 esterase inhibitor may play a critical role in regulating vascular permeability in the acute phase following the burn injury.

Fat Injection for Cases of Severe Burn Outcomes: A New Perspective of Scar Remodeling and Reduction

BACKGROUND

Despite civilization and progress, burns occur frequently in the world. Remarkable discoveries of wound healing mechanisms have been reported. On the other hand, long-term outcomes from burn injuries represent a barrier to improvement of patients' social, functional, and psychological condition. Lipofilling, described since the 1980s, currently is used for several clinical applications. This study aimed to verify whether lipofilling could ameliorate scar remodeling in three clinical cases.

METHODS

Three adult patients with hemifacial hypertrophic scars and keloids resulting from severe burns 2 to 13 years previously were selected. The patients were treated by injection of adipose tissue harvested from abdominal subcutaneous fat and processed according to Coleman's technique. Two injections (with a 13-month interval between) were administered at the dermohypodermal junction. Histologic examination of scar tissue punch biopsies (hematoxylin-eosin staining) before and after the treatment was performed as well as magnetic resonance scan with contrast.

RESULTS

The clinical appearance and subjective patient feelings after a 6-month follow-up period suggest considerable improvement in the mimic features, skin texture, and thickness. Histologic examination shows patterns of new collagen deposition, local hypervascularity, and dermal hyperplasia in the context of new tissue, with high correspondence to the original.

CONCLUSIONS

The preliminary results show that lipofilling improves scar quality and suggest a tissue regeneration enhancing process.

Volume Resuscitation in Patients With High-Voltage Electrical Injuries

Volume resuscitation of patients with high-voltage electrical injuries (>1000 V) is a more complex challenge than standard burn resuscitation. High voltages penetrate deep tissues. These deep injuries are not accounted for in resuscitation formulae dependent on percentage of cutaneous burn. Myonecrosis occurring from direct electrical injury and secondary compartment syndromes can result in rhabdomyolysis, compromising renal function and urine output. Urine output is the primary end point, with a goal of 1 mL/kg/h for adult patients with high-voltage electrical injuries. As such, secondary resuscitation end points of laboratory values, such as lactate, base deficit, hemoglobin, and creatinine, as well as hemodynamic monitoring, such as mean arterial pressure and thermodilution techniques, can become crucial in guiding optimum administration of resuscitation fluids. Mannitol and bicarbonates are available but have limited support in the literature. High-voltage electrical injury patients often develop acute kidney injury requiring dialysis and have increased risks of chronic kidney disease and mortality. Continuous venovenous hemofiltration is a well-supported adjunct to clear the myoglobin load that hemodialysis cannot from circulation.

Delivery systems of current biologicals for the treatment of chronic cutaneous wounds and severe burns

While wound therapy remains a clinical challenge in current medical practice, much effort has focused on developing biological therapeutic approaches. This paper presents a comprehensive review of delivery systems for current biologicals for the treatment of chronic wounds and severe burns. The biologicals discussed here include proteins such as growth factors and gene modifying molecules, which may be delivered to wounds free, encapsulated, or released from living systems (cells, skin grafts or skin equivalents) or biomaterials. Advances in biomaterial science and technologies have enabled the synthesis of delivery systems such as scaffolds, hydrogels and nanoparticles, designed to not only allow spatially and temporally controlled release of biologicals, but to also emulate the natural extracellular matrix microenvironment. These technologies represent an attractive field for regenerative wound therapy, by offering more personalised and effective treatments.

Current and Emerging Topical Antibacterials and Antiseptics: Agents, Action, and Resistance Patterns

Bacterial skin infections represent some of the most common infectious diseases globally. Prevention and treatment of skin infections can involve application of a topical antimicrobial, which may be an antibiotic (such as mupirocin or fusidic acid) or an antiseptic (such as chlorhexidine or alcohol). However, there is limited evidence to support the widespread prophylactic or therapeutic use of topical agents. Challenges involved in the use of topical antimicrobials include increasing rates of bacterial resistance, local hypersensitivity reactions (particularly to older agents, such as bacitracin), and concerns about the indiscriminate use of antiseptics potentially coselecting for antibiotic resistance. We review the evidence for the major clinical uses of topical antibiotics and antiseptics. In addition, we review the mechanisms of action of common topical agents and define the clinical and molecular epidemiology of antimicrobial resistance in these agents. Moreover, we review the potential use of newer and emerging agents, such as retapamulin and ebselen, and discuss the role of antiseptic agents in preventing bacterial skin infections. A comprehensive understanding of the clinical efficacy and drivers of resistance to topical agents will inform the optimal use of these agents to preserve their activity in the future.

Keratinocyte growth factor and the expression of wound-healing-related genes in primary human keratinocytes from burn patients

PURPOSE

To evaluate the effect of keratinocyte growth factor (KGF) treatment on the expression of wound-healing-related genes in cultured keratinocytes from burn patients.

METHODS

Keratinocytes were cultured and divided into 4 groups (n=4 in each group): TKB (KGF-treated keratinocytes from burn patients), UKB (untreated keratinocytes from burn patients), TKC (KGF-treated keratinocytes from controls), and UKC (untreated keratinocytes from controls). Gene expression analysis using quantitative polymerase chain reaction (qPCR) array was performed to compare (1) TKC versus UKC, (2) UKB versus UKC, (3) TKB versus UKC, (4) TKB versus UKB, (5) TKB versus TKC, and (6) UKB versus TKC.

RESULTS

Comparison 1 showed one down-regulated and one up-regulated gene; comparisons 2 and 3 resulted in the same five down-regulated genes; comparison 4 had no significant difference in relative gene expression; comparison 5 showed 26 down-regulated and 7 up-regulated genes; and comparison 6 showed 25 down-regulated and 11 up-regulated genes.

CONCLUSION

There was no differential expression of wound-healing-related genes in cultured primary keratinocytes from burn patients treated with keratinocyte growth factor.

Healing of canine skin incisions made with monopolar electrosurgery versus scalpel blade

OBJECTIVE

To determine the influence of monopolar electrosurgery in cutting mode set at 10, 20, or 30 W on surgery time, hemostasis, and healing of cutaneous wounds compared to scalpel incisions.

STUDY DESIGN

Randomized blinded control trial.

ANIMALS

Dogs (n = 15).

METHODS

Four skin incisions were created on either side of the dorsal midline with a scalpel, or monopolar electrosurgery at 10, 20, and 30 W. Surgical time and incisional bleeding were measured. Each incision was assessed daily for edema, erythema and discharge, and complications. Healing was evaluated via histology at 7 days. Results were analyzed for significance at P ≤ .05.

RESULTS

Surgical time and hemostasis were improved in all electrosurgery groups. Erythema was reduced in all electrosurgical incisions for days 1-4, but was greater in wounds created via electrosurgery at 20 W than those made with a scalpel blade by day 7. No difference was noted in the degree of edema or presence of wound discharge. All histologic variables of tissue healing were lower in electrosurgical incisions than scalpel incisions (P < .001). Ten incisional complications occurred, all associated with electrosurgery.

CONCLUSIONS

The use of monopolar electrosurgery at 10, 20, and 30 W in a cutting waveform improved hemostasis and surgical time when incising canine skin, but delayed healing and increased complications within the first 7 days compared to scalpel incisions.

Methanol Extract from Anogeissus leiocarpus (DC) Guill. et Perr. (Combretaceae) Stem Bark Quenches the Quorum Sensing of Pseudomonas aeruginosa PAO1

Background: Due to its extensive arsenal of virulence factors and inherent resistance to antibiotics, Pseudomonas aeruginosa is a threat particularly in immunocompromised patients. Considering the central role of quorum sensing in the production of virulence factors, inhibition of bacterial communication mechanism constitute an opportunity to attenuate pathogenicity of bacteria resistant to available antibiotics. Our study aimed to assess the anti-quorum sensing activity of Anogeissus leiocarpus, traditionally used in Burkina Faso, for the treatment of infected burn wounds. Methods: Investigations were carried out on methanol extract from A. leiocarpus stem bark. The reporter strains Chromobacterium violaceum CV026 and P. aeruginosa PAO1 derivatives were used to evidence any interference with the bacterial quorum sensing and expression of related genes. P. aeruginosa PAO1 was used to measure the impact on pyocyanin production. Results: At a sub-inhibitory concentration (100 µg/mL), A. leiocarpus methanol extract quenched the quorum sensing mechanism of P. aeruginosa PAO1 by down-streaming the rhlR gene, with a subsequent reduction of pyocyanin production. Moreover, the antioxidant polyphenols evidenced are able to reduce the oxidative stress induced by pyocyanin. Conclusion: The antioxidant and anti-quorum sensing activities of A. leiocarpus stem bark could justify its traditional use in the treatment of infected burn wounds.

The Burn Wound Microenvironment

Significance: While the survival rate of the severely burned patient has improved significantly, relatively little progress has been made in treatment or prevention of burn-induced long-term sequelae, such as contraction and fibrosis. Recent Advances: Our knowledge of the molecular pathways involved in burn wounds has increased dramatically, and technological advances now allow large-scale genomic studies, providing a global view of wound healing processes. Critical Issues: Translating findings from a large number of in vitro and preclinical animal studies into clinical practice represents a gap in our understanding, and the failures of a number of clinical trials suggest that targeting single pathways or cytokines may not be the best approach. Significant opportunities for improvement exist. Future Directions: Study of the underlying molecular influences of burn wound healing progression will undoubtedly continue as an active research focus. Increasing our knowledge of these processes will identify additional therapeutic targets, supporting informed clinical studies that translate into clinical relevance and practice.

Update in the management of critically ill burned patients

The management of critically ill burn patients is challenging. These patients have to be managed in specialized centers, where the expertise of physicians and nursing personnel guarantees the best treatment. Mortality of burn patients has improved over the past decades due to a better understanding of burn shock pathophysiology, optimal surgical management, infection control and nutritional support. Indeed, a more aggressive resuscitation, early excision and grafting, the judicious use of topical antibiotics, and the provision of an adequate calorie and protein intake are key to attain best survival results. General advances in critical care have also to be implemented, including protective ventilation, glycemic control, selective decontamination of the digestive tract, and implementation of sedation protocols.

Mesenchymal stem cells: potential for therapy and treatment of chronic non-healing skin wounds

Wound healing is a complex physiological process including overlapping phases (hemostatic/inflammatory, proliferating and remodeling phases). Every alteration in this mechanism might lead to pathological conditions of different medical relevance. Treatments for chronic non-healing wounds are expensive because reiterative treatments are needed. Regenerative medicine and in particular mesenchymal stem cells approach is emerging as new potential clinical application in wound healing. In the past decades, advance in the understanding of molecular mechanisms underlying wound healing process has led to extensive topical administration of growth factors as part of wound care. Currently, no definitive treatment is available and the research on optimal wound care depends upon the efficacy and cost-benefit of emerging therapies. Here we provide an overview on the novel approaches through stem cell therapy to improve cutaneous wound healing, with a focus on diabetic wounds and Systemic Sclerosis-associated ulcers, which are particularly challenging. Current and future treatment approaches are discussed with an emphasis on recent advances.

Caffeic acid phenethyl ester improves burn healing in rats through anti-inflammatory and antioxidant effects

Although caffeic acid phenethyl ester (CAPE) has beneficial properties, its anti-inflammatory and antioxidant effects on healing burn injury have not been investigated as yet. Female Wistar rats were divided in two groups: burn and burn + CAPE. A scald injury (burn) was performed. CAPE treatment (10 µmol kg) began immediately after the burn and lasted for 14 days. Euthanasia was performed 14 or 70 days after burning. Seven, 21, and 70 days after burning, burn + CAPE group presented smaller wound area. Increase in reepithelialization was observed in burn + CAPE group 28 and 63 days after burning. Fourteen days after wounding, burn + CAPE group presented diminished myeloperoxidase activity and nitrite levels, reduced CD68 and platelet endothelial cell adhesion molecule 1 protein expression, and less oxidative damage (decrease in malondialdehyde (MDA) and carbonyl levels in plasma and lesion extracts). Seventy days after burning, the amount of myofibroblasts and macrophages (CD68 positive) was decreased and the amount of hydroxyproline was increased in burn + CAPE group. Treatment with CAPE improved burn wound healing, showing decrease in inflammatory parameters and in oxidative damage.

Microvascular endothelial cell hyperpermeability induced by endogenous caspase 3 activator staurosporine

BACKGROUND

Microvascular hyperpermeability following conditions such as hemorrhagic shock occurs mainly owing to disruption of the adherens junctional protein complex in endothelial cells. The objective of this study was to examine the action of staurosporine, a potent activator of endogenous caspase 3 on the adherens junction and the cellular pathway through which it causes possible endothelial cell barrier dysfunction.

METHODS

Rat lung microvascular endothelial cell (RLMEC) permeability was measured by fluorescein isothiocyanate-albumin flux across the monolayer in a Transwell plate. Integrity of the endothelial cell adherens junctions was studied using immunofluorescence of β-catenin and vascular endothelial-cadherin. Mitochondrial reactive oxygen species formation was determined by using dihydrorhodamine 123 and mitochondrial transmembrane potential by JC-1 fluorescent probe and flow cytometry. Caspase 3 enzyme activity was assayed fluorometrically. Cell death assay in RLMECs was performed using propidium iodide staining and analyzed by flow cytometry.

RESULTS

Staurosporine (1 µM)-treated RLMEC monolayers showed significant increase in permeability, which was decreased by pretreatment with caspase 3 specific inhibitor, Z-DEVD-FMK (p < 0.05). Immunofluorescence studies showed staurosporine induced disruption of the adherens junction, which was reversed by Z-DEVD-FMK. Staurosporine treatment led to an increase in mitochondrial reactive oxygen species formation and a decrease in mitochondrial transmembrane potential. Furthermore, staurosporine induced a significant increase in caspase 3 activity (p < 0.05) but not cell death in RLMECs (p < 0.05).

CONCLUSION

Staurosporine-induced disruption of the adherens junction and microvascular endothelial cell hyperpermeability is associated with the activation of mitochondrial "intrinsic" apoptotic signaling cascade but without causing endothelial cell death. Our results suggest that prevention of mitochondrial-mediated activation of caspase 3 has therapeutic potential against microvascular hyperpermeability.

Effects of puerarin on the inflammatory role of burn-related procedural pain mediated by P2X(7) receptors

BACKGROUND

Burn injury can induce an inflammatory response in the blood and wound of patients. Procedural activities in burn patients are particularly problematic in burn care due to their high intensity and frequency; hence, procedural pain evoked by burn dressing changes is a common severe issue. Previous studies demonstrated that purinergic signalling is one of the major pathways involved in the initiation, progression and down-regulation of the inflammatory response. Adenosine 5'-triphosphate (ATP) contributes to inflammation, and increased extracellular ATP levels amplify inflammation in vivo via the P2X7 receptor. In the present study, the effect of puerarin, an active ingredient extracted from Chinese herbal medicine Ge Gen, on pain relief of burn patients during dressing change and the mechanism related to the regulation of the purinergic signalling pathway were investigated.

METHODS

Burn patients were randomly divided into the normal saline group (NS-treated burn patients) and the puerarin-treated group (PUE-treated burn patients), and healthy volunteers were recruited as a control group. The visual Analogue Scale (VAS) scores, heart rate (HR) and respiratory rate (RR) of NS- and PUE-treated burn patients were observed. In addition, interleukin (IL)-1 and IL-4 levels in blood samples, as well as expression of P2X7 receptor messenger RNA (mRNA) and protein in peripheral blood mononuclear cells (PBMCs) were determined.

RESULTS

The IL-1 levels in the PUE-treated burn patients at post-dressing changes were significantly decreased in comparison with those in NS-treated burn patients; in contrast, the IL-4 levels in PUE-treated burn patients were increased. The expression levels of P2X7 protein and mRNA in PBMCs of PUE-treated burn patients were significantly decreased in comparison with those in NS-treated burn patients.

CONCLUSIONS

The inflammation and associated pain involved in dressing changes of burn patients were relieved by puerarin treatment. The effects were correlated with the decreased expression level of P2X7 receptor mRNA and protein in PBMCs of burn patients.

Article Commentary: OB-GYN Surgeries: Why We Should Recommend to Our Patients a Preventive Management for Keloids and Hypertrophic Scars

As with all surgical specialties, gynecologists and obstetricians routinely employ surgical interventions, depending on the exact nature of the problem that they are treating. Surgery is the mainstay of gynecological therapies, and in obstetrics, surgery is frequent.

Myosin light chain kinase signaling in endothelial barrier dysfunction

Microvascular barrier dysfunction is a serious problem that occurs in many inflammatory conditions, including sepsis, trauma, ischemia-reperfusion injury, cardiovascular disease, and diabetes. Barrier dysfunction permits extravasation of serum components into the surrounding tissue, leading to edema formation and organ failure. The basis for microvascular barrier dysfunction is hyperpermeability at endothelial cell-cell junctions. Endothelial hyperpermeability is increased by actomyosin contractile activity in response to phosphorylation of myosin light chain by myosin light chain kinase (MLCK). MLCK-dependent endothelial hyperpermeability occurs in response to inflammatory mediators (e.g., activated neutrophils, thrombin, histamine, tumor necrosis factor alpha, etc.), through multiple cell signaling pathways and signaling molecules (e.g., Ca(++) , protein kinase C, Src kinase, nitric oxide synthase, etc.). Other signaling molecules protect against MLCK-dependent hyperpermeability (e.g., sphingosine-1-phosphate or cAMP). In addition, individual MLCK isoforms play specific roles in endothelial barrier dysfunction, suggesting that isoform-specific inhibitors could be useful for treating inflammatory disorders and preventing multiple organ failure. Because endothelial barrier dysfunction depends upon signaling through MLCK in many instances, MLCK-dependent signaling comprises multiple potential therapeutic targets for preventing edema formation and multiple organ failure. The following review is a discussion of MLCK-dependent mechanisms and cell signaling events that mediate endothelial hyperpermeability.

Lycopene inhibits caspase-3 activity and reduces oxidative organ damage in a rat model of thermal injury

Oxidative stress has been implicated in various pathological processes including burn induced multiple organ damage. This study investigated the effects of lycopene treatment against oxidative injury in rats with thermal trauma. Under ether anesthesia, shaved dorsum of the rats was exposed to 90°C bath for 10s to induce burn and treated either vehicle (olive oil) or lycopene (50mg/kg orally). Rats were decapitated 48 h after injury and the tissue samples from lung and kidney were taken for histological analysis and the determination of malondialdehyde (MDA) and glutathione (GSH) levels, myeloperoxidase (MPO), superoxide dismutase (SOD), catalase (CAT) and caspase-3 activities. Proinflammatory cytokines, TNF-α and IL-1β, were assayed in blood samples. Severe skin scald injury caused a significant decrease in GSH levels, SOD and CAT activities, and significant increases in MDA levels, MPO and caspase-3 activities of tissues. Similarly, plasma TNF-α and IL-1β were elevated in the burn group as compared to the control group. Lycopene treatment reversed all these biochemical indices. According to the findings of the present study, lycopene possesses antiinflammatory, antiapoptotic and antioxidant effects that prevents burn-induced oxidative damage in remote organs.

Tigecycline accelerates staphylococcal-infected burn wound healing through matrix metalloproteinase-9 modulation

OBJECTIVES

We investigated the in vivo efficacy of tigecycline, a new glycylcycline (a tetracycline derivative), in the management of methicillin-resistant Staphylococcus aureus (MRSA)-infected experimental surgical wounds in rats. The main outcome measures were quantitative bacterial culture, histological examination and immunohistochemical expression of matrix metalloproteinase-9 (MMP-9) and collagen IV.

METHODS

An animal model was used to compare the in vivo efficacy of teicoplanin and tigecycline in the treatment of burn wound infections by S. aureus. A copper bar, heated in boiling water, was placed on the paraspinal site of each rat, resulting in full thickness burns. A small gauze was placed over each burn and then inoculated with 5 × 10(7) cfu of S. aureus ATCC 43300. To mimic the clinical situation in burn patients, surgical debridement was performed 48 h after the injury. The wounds were left to heal by secondary intention. The study included an uninfected control group that did not receive any treatment, a contaminated group that did not receive any treatment, and two contaminated groups treated with intraperitoneal tigecycline (2 mg/kg) and teicoplanin (7 mg/kg), respectively.

RESULTS

All antibiotic treatments were significantly effective. Tigecycline showed the highest antimicrobial activity, with a better impact on histological results. Infected rats treated with tigecycline showed a significant decrease in MMP-9 expression both in epithelium and in dermis compared with rats treated with teicoplanin.

CONCLUSIONS

Tigecycline, besides its antimicrobial activity, exerts an important modulatory effect on MMP-9, accelerating wound healing in staphylococcal-infected burns.

High-dose vitamin C treatment reduces capillary leakage after burn plasma transfer in rats

Oxidative stress after burn injuries leads to systemic capillary leakage and leukocyte activation. This study evaluates whether antioxidative treatment with high-dose vitamin C leads to burn edema reduction and prevention of leukocyte activation after burn plasma transfer. Donor rats underwent a burn (n = 7; 100 degrees C water, 12 seconds, 30% body surface area) or sham burn (37 degrees C water; n = 2) procedure and were killed after 4 hours for plasma harvest. This plasma was administered to study rats (continuous infusion). Rats were randomized to four groups (n = 8 each; burn plasma alone [BP]; burn plasma/vitamin C-bolus 66 mg/kg and maintenance dose 33 mg/kg/hr [VC66]; burn plasma/vitamin C-bolus 33 mg/kg and maintenance dose 17.5 mg/kg/hr [VC33]; and sham burn plasma [SB]). Intravital fluorescence microscopy in the mesentery was performed at 0, 60, and 120 minutes for microhemodynamic parameters, leukocyte adherence, and fluorescein isothiocyanate-albumin extravasation. No differences were observed in microhemodynamics at any time. Burn plasma induced capillary leakage, which was significantly higher compared with sham burn controls (P < .001). VC66 treatment reduced microvascular barrier dysfunction to sham burn levels, whereas VC33 had no significant effect. Leukocyte sticking increased after burn plasma infusion, which was not found for sham burn. Vitamin C treatment did not influence leukocyte activation (P > .05). Burn plasma transfer leads to systemic capillary leakage. High-dose vitamin C treatment (bolus 66 mg/kg and maintenance dose 33 mg/kg/hr) reduces endothelial damage to sham burn levels, whereas half the dose is inefficient. Leukocyte activation is not influenced by antioxidative treatment. Therefore, capillary leakage seems to be independent from leukocyte-endothelial interactions after burn plasma transfer. High-dose vitamin C should be considered for parenteral treatment in every burn patient.

Wound trauma mediated inflammatory signaling attenuates a tissue regenerative response in MRL/MpJ mice

Background

Severe trauma can induce pathophysiological responses that have marked inflammatory components. The development of systemic inflammation following severe thermal injury has been implicated in immune dysfunction, delayed wound healing, multi-system organ failure and increased mortality.

Methods

In this study, we examined the impact of thermal injury-induced systemic inflammation on the healing response of a secondary wound in the MRL/MpJ mouse model, which was anatomically remote from the primary site of trauma, a wound that typically undergoes scarless healing in this specific strain. Ear-hole wounds in MRL/MpJ mice have previously displayed accelerated healing and tissue regeneration in the absence of a secondary insult.

Results

Severe thermal injury in addition to distal ear-hole wounds induced marked local and systemic inflammatory responses in the lungs and significantly augmented the expression of inflammatory mediators in the ear tissue. By day 14, 61% of the ear-hole wounds from thermally injured mice demonstrated extensive inflammation with marked inflammatory cell infiltration, extensive ulceration, and various level of necrosis to the point where a large percentage (38%) had to be euthanized early during the study due to extensive necrosis, inflammation and ear deformation. By day 35, ear-hole wounds in mice not subjected to thermal injury were completely closed, while the ear-hole wounds in thermally injured mice exhibited less inflammation and necrosis and only closed partially (62%). Thermal injury resulted in marked increases in serum levels of IL-6, TNFα, KC (CXCL1), and MIP-2α (CXCL2). Interestingly, attenuated early ear wound healing in the thermally injured mouse resulted in incomplete tissue regeneration in addition to a marked inflammatory response, as evidenced by the histological appearance of the wound and increased transcription of potent inflammatory mediators.

Conclusion

These findings suggest that the observed systemic inflammatory response of a severe thermal injury undoubtedly has an adverse effect on wound healing and tissue regeneration.

Myosin light chain kinase in microvascular endothelial barrier function

Microvascular barrier dysfunction is implicated in the initiation and progression of inflammation, posttraumatic complications, sepsis, ischaemia-reperfusion injury, atherosclerosis, and diabetes. Under physiological conditions, a precise equilibrium between endothelial cell-cell adhesion and actin-myosin-based centripetal tension tightly controls the semi-permeability of microvascular barriers. Myosin light chain kinase (MLCK) plays an important role in maintaining the equilibrium by phosphorylating myosin light chain (MLC), thereby inducing actomyosin contractility and weakening endothelial cell-cell adhesion. MLCK is activated by numerous physiological factors and inflammatory or angiogenic mediators, causing vascular hyperpermeability. In this review, we discuss experimental evidence supporting the crucial role of MLCK in the hyperpermeability response to key cell signalling events during inflammation. At the cellular level, in vitro studies of cultured endothelial monolayers treated with MLCK inhibitors or transfected with specific inhibiting peptides have demonstrated that induction of endothelial MLCK activity is necessary for hyperpermeability. Ex vivo studies of live microvessels, enabled by development of the isolated, perfused venule method, support the importance of MLCK in endothelial permeability regulation in an environment that more closely resembles in vivo tissues. Finally, the role of MLCK in vascular hyperpermeability has been confirmed with in vivo studies of animal disease models and the use of transgenic MLCK210 knockout mice. These approaches provide a more complete view of the role of MLCK in vascular barrier dysfunction.

Impact of thermal injury on wound infiltration and the dermal inflammatory response

Healing of the burn wound is a critical component of the burn patient's successful recovery. While inflammation is a critical component of the healing process, it is unknown whether the inflammatory response differs between non-burn and burn wounds. To study this, mice were subjected to major burn injury or sham procedure. Wound cells were collected by implantation of polyvinyl alcohol sponges beneath the burn site in injured mice or beneath uninjured skin in sham mice (i.e., non-burn wound). Three days thereafter, skin, wound fluid, and infiltrating cells were collected for analysis. Significant levels of tumor necrosis factor (TNF)-alpha, interleukin (IL-6), monocyte chemoattractant protein (MCP)-1, and keratinocyte-derived chemokine (KC) were observed in burn wound tissue and the wound fluid from both non-burn and burn wounds. Burn injury induced 3-fold higher levels of KC and 50-fold higher levels of IL-6 in the wound fluid compared with non-burn injury. Significant numbers of the cells from both burn and non-burn wounds were CD11b(+), GR1(+), and F4/80(+), suggestive of a myeloid suppressor cell phenotype, whereas CD3(+) T-cells were negligible under both conditions. LPS induced TNF-alpha, IL-6, IL-10, MCP-1, KC, and nitric oxide production in both cell populations, however, IL-6, IL-10, MCP-1, and KC levels were suppressed in burn wound cell cultures. These findings indicate that significant differences in the wound inflammatory response exist between burn and non-burn cutaneous wounds and that the unique characteristics of the inflammatory response at the burn site may be an important contributing factor to post-burn wound healing complications.

A microarray analysis of temporal gene expression profiles in thermally injured human skin

Partial-thickness burns incite a multitude of responses which eventually culminate in cutaneous wound repair. We hypothesized that these events would evoke extensive alterations in gene expression thereby orchestrating the complexity of spatial and temporal events that characterize "normal" human wound healing. In the present study, gene expression from partial-thickness areas at defined temporal periods (1-3 days, 4-6 days, and 7-18 days) after injury were compared to normal non-wounded skin. Gene alterations proved extensive (2286 genes). Statistically significant alterations were noted among increased and decreased genes expressed in the three different temporal groupings. Our foundational data (based on samples from 45 individuals) provide a comprehensive molecular gene expression portrait of the cutaneous reparative responses that are initiated during the first 17 days after injury. Our efforts also represent an initial endeavor to move beyond the historically defined "morphological phases" of wound repair toward reporting molecular clues that define the temporal sequence of healing in human subjects. Further analysis of genes that are either affected or remain not affected following injury to normal skin is expected to identify potential targets for therapeutic augmentation or silencing.

[Burn trauma. Part 1: pathophysiology, preclinical care and emergency room management]

Severe burn injuries are rare and represent less than 1% of all medical emergencies. At the scene of the accident self-protection is important. The progress of thermal injury should be stopped, while cold water therapy is usually not indicated as the resulting hypothermia severely reduces the prognosis. A thorough body check reveals the burn size, depth and presence of co-injuries. Volume depletion is the main pathophysiological reason for burn shock. Early infusion therapy is of prognostic significance. Sufficient analgesia has to be established. Intubation is not generally indicated even with extensive burns, whereas early intubation can be life-saving in the case of circular thoracic burns, face burns and inhalation trauma. Local or systemic administration of corticosteroids is not indicated. Transfer to a specialized burn unit depends on burn size and depth. Emergency room management includes stabilization of vital functions, evaluation of co-injuries and initiation of the specific surgical and intensive care therapy.

Tangential excision of burn wounds

Mortality from burns has significantly declined during the last few decades. The decline in mortality is attributed to number of factors that improved over the years including the surgical technique of tangential excision. Since its introduction, the procedure has been under continuous scrutiny in efforts to determine the efficacy of the procedure. Tangential excision must be performed with careful attention to blood loss, patient body temperature, and viable tissue in order to be successful. The procedure has shown signs of improvement of the more conservative methods of burn treatment. The results, however, have some differing efficacy among the different body areas. It has been indicated that tangential excision provides better cosmetic results in facial burns. For hand burns, however, the results have not been significantly better than the conservative methods of treatment.

Gammadelta T-cells: potential regulators of the post-burn inflammatory response

Severe burn induces an immunopathological response that contributes to the development of a systemic inflammatory response (SIRS) and subsequent multiple organ failure. While, multiple immune cells type (T-cells, macrophages, neutrophils) are involved in this response, recent evidence suggests that a unique T-cell subset, gammadelta T-cells are central in the response to injury. While gammadelta T-cells represent only a small percentage of the total T-cell population, they display specific functional characteristics that uniquely position them in the immune/inflammatory axis to influence a number of important aspects of the body's response to burn. This review will focus on the potential regulator role of gammadelta T-cells in immunopathological response following burn and thereby their potential as therapeutic targets for affecting inflammation and healing.

Burn injury-induced alterations in wound inflammation and healing are associated with suppressed hypoxia inducible factor-1alpha expression

A major complication associated with burn injury is delayed wound healing. While healing of the burn injury site is essential, healing of distal injury sites caused by surgical interventions and other processes also is important. The impact of burn injury on healing of these distal wound sites is not understood clearly. To study this, mice were subjected to major burn injury or a sham procedure. Immediately following, excisional wounds were made on the dorsal surface caudal to the burn site and wound closure was monitored over a 7-d period by planimetry. In a second series of experiments, plasma and excisional wounds were collected for in vitro analysis of cyto- and chemokine levels, L-arginine metabolism, and hypoxia-inducible factor (HIF)-1alpha expression. At 1-7 d post-injury, a significant inflammatory response was evident in both groups, but the healing process was delayed in the burn-injured mice. At 3 d post-injury, wound levels of tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6), and keratinocyte-derived chemokine were suppressed in the burn group. This difference in the wound inflammatory response was independent of changes in L-arginine metabolism (nitrate levels, inducible nitric oxide synthase expression, arginase activity), but correlated with a marked reduction in HIF-1alpha protein levels. In conclusion, these findings suggest that HIF-1alpha and the inflammatory response play a significant role in wound healing, and reduced levels of HIF-1alpha contribute to the impaired healing response post-burn.

Toll-like receptor 4 contributes to microvascular inflammation and barrier dysfunction in thermal injury

Systemic and microvascular inflammation plays a key role in the development of multiple organ failure after infection, sepsis, and traumatic injury. Toll-like receptors (TLRs) regulate host responses to pathogens and sterile, injury-associated inflammatory responses. We investigated whether TLR-4 contributes to microvascular dysfunction during thermal injury in vivo in anesthetized wild-type or TLR-4 (-/-) mice receiving either a 25% total body surface area full-thickness scald burn or sham treatment on the dorsal skin. Using intravital microscopy, we assessed the hemodynamics and leukocyte dynamics in the mesenteric microvasculature as representative of the splanchnic microcirculation at a site remote from the burn wound. The transvascular flux of fluorescein isothiocyanate-albumin across mesenteric venules was measured as an indicator of microvascular permeability. Furthermore, cultured microvascular endothelial cell models were used to evaluate the endothelial-specific mechanisms involved in TLR-4-mediated barrier dysfunction. The results showed significantly elevated microvascular permeability in wild-type mice after burn, whereas this response was markedly attenuated in TLR-4 (-/-) mice. Burn injury also increased leukocyte adhesion in mesenteric venules of wild-type mice, and a blunted leukocyte response was seen in the TLR-4 mice. Treatment of endothelial cell monolayers with burn plasma induced a rapid reduction in the transendothelial electrical resistance measured by electric cell-substrate impedance sensing, indicative of endothelial cell-cell adhesive barrier dysfunction. Reducing expression of TLR-4 with siRNA treatment attenuated this response. Taken together, these data indicate that TLR-4 plays an important role in microvascular leakage and leukocyte adhesion under the inflammatory condition associated with nonseptic thermal injury.

Fat injection for cases of severe burn outcomes: a new perspective of scar remodeling and reduction

BACKGROUND

Despite civilization and progress, burns occur frequently in the world. Remarkable discoveries of wound healing mechanisms have been reported. On the other hand, long-term outcomes from burn injuries represent a barrier to improvement of patients' social, functional, and psychological condition. Lipofilling, described since the 1980s, currently is used for several clinical applications. This study aimed to verify whether lipofilling could ameliorate scar remodeling in three clinical cases.

METHODS

Three adult patients with hemifacial hypertrophic scars and keloids resulting from severe burns 2 to 13 years previously were selected. The patients were treated by injection of adipose tissue harvested from abdominal subcutaneous fat and processed according to Coleman's technique. Two injections (with a 13-month interval between) were administered at the dermohypodermal junction. Histologic examination of scar tissue punch biopsies (hematoxylin-eosin staining) before and after the treatment was performed as well as magnetic resonance scan with contrast.

RESULTS

The clinical appearance and subjective patient feelings after a 6-month follow-up period suggest considerable improvement in the mimic features, skin texture, and thickness. Histologic examination shows patterns of new collagen deposition, local hypervascularity, and dermal hyperplasia in the context of new tissue, with high correspondence to the original.

CONCLUSIONS

The preliminary results show that lipofilling improves scar quality and suggest a tissue regeneration enhancing process.

Proinflammatory cytokines mediating burn-injury pain

Thermal burns induce pain at the site of injury, mechanical hyperalgesia, associated with a complex time-dependent inflammatory response. To determine the contribution of inflammatory mediators to burn injury-induced mechanical hyperalgesia, we measured dynamic changes in the levels of three potent hyperalgesic cytokines, interleukin IL-1 beta, IL-6, and tumor necrosis factor-alpha (TNFalpha), in skin of the rat, following a partial-thickness burn injury. Only IL-6 demonstrated a sustained increase ipsilateral but not contralateral to the burn, correlating with the prolonged ipsilateral mechanical hyperalgesia. Spinal intrathecal injection of oligodeoxynucleotides antisense for gp130, a receptor subunit shared by members of the IL-6 family of cytokines, attenuated both burn- and intradermal IL-6-induced hyperalgesia, as did intradermal injection of anti-IL-6 function blocking antibodies. These studies suggest that IL-6 is an important mediator of burn-injury pain.

Regulation of the postburn wound inflammatory response by gammadelta T-cells

Healing of the burn injury site is a critical component of the patient's successful recovery from this form of trauma. Previous studies from our laboratory have demonstrated that gammadelta T-cells via the production of growth factors are important in burn wound healing. Nonetheless, the role of these cells in burn wound inflammation remains unknown. To study this, wild-type (WT) and gammadelta T-cell receptor-deficient (delta TCR) C57BL/6 male mice were subjected to burn injury or sham procedure. Wound cells were collected by implantation of polyvinyl alcohol sponges beneath the burn site in injured mice or beneath uninjured skin in sham mice. At 3 days after injury, infiltrating cells, wound fluid, and skin were collected for analysis. Burn injury markedly increased skin tumor necrosis factor-alpha (TNF-alpha) and monocyte chemoattractant protein 1 levels. In WT mice, the numbers of infiltrating cells were similar between nonburn wounds and burn wounds. In contrast, deltaTCRmice displayed a 6-fold reduction in the cellular infiltrate. Burn injury in WT mice caused a marked increase in burn wound TNF-alpha, monocyte chemoattractant protein 1, and interleukin 6 content as compared with nonburn wounds, whereas in delta TCRmice, the burn-induced increase of TNF-alpha and interleukin 6 was not observed. The wound cell infiltrate at 3 days postinjury was devoid of gammadelta T-cells in WT mice. It was predominately of myeloid origin expressing high levels of CD11b and F4/80. In conclusion, these findings suggest that resident gammadelta T-cells are important in the recruitment of inflammatory cells and regulation of the inflammatory response at the wound site after thermal injury.

Serum enzymes in thermal injury

Various metabolic and biological changes follow burn injury. Serum Thio-barbituric acid reactive substances (TBARS), transaminases, alkaline phosphatase and amylase were measured in 43 patients with thermal injury over the first 10 days of post burn period. No clear correlation between elevated serum enzymes except amylase and the burn size was observed on admission. Mean serum TBARS were significantly increased in the burn patients. Transaminases values increased till 5(th) day then declined on 10(th) day, whereas alkaline phosphatase and amylase activities continued to rise till day 10. It is concluded that functional disturbances occur in liver and pancreas around a week after thermal injury. Monitoring serum ALP and amylase in postburn period has valuable prognostic importance.

Topical p38 MAPK inhibition reduces bacterial growth in an in vivo burn wound model

BACKGROUND

Although the inflammatory response is a prerequisite for wound healing, excessive activation of the innate immune system can induce epithelial cell damage and apoptosis, which may further compromise dermal integrity. In a noninfectious burn wound model, we previously demonstrated that topical inhibition of p38 MAPK, an important inflammatory signaling pathway, attenuated epithelial cell damage and apoptosis. We now question whether attenuating local inflammation would weaken bacterial wound resistance and compromise host defense.

METHODS

Rats received 30% total body surface area burn, and the wound was treated with topical application of a p38 MAPK inhibitor or vehicle. At 24 hours after injury, burn wounds were inoculated with Pseudomonas aeruginosa. At 48 hours postinjury, animals were sacrificed, and the burn wound was analyzed.

RESULTS

Inoculating burn wounds induced significant bacterial growth. Dermal inflammatory changes were markedly accentuated in the inoculated animals. Topical p38 MAPK inhibition reduced the proinflammatory cytokine expression in the burn wounds and neutrophil sequestration with or without bacterial inoculation. Interestingly, the bacterial wound growth was significantly attenuated in animals treated with topical p38 MAPK inhibitor.

CONCLUSIONS

Topical p38 MAPK inhibition attenuated wound inflammation without interfering with bacterial host defense. Attenuation of excessive burn wound inflammatory signaling may prevent secondary damage of the dermal barrier and reduce the growth of opportunistic pathogens.

Proteomic investigation of human burn wounds by 2D-difference gel electrophoresis and mass spectrometry

BACKGROUND

In humans, thermal cutaneous injury represents a serious traumatic event that induces a host of dynamic alterations. Unfortunately the molecular mechanisms that underlie these serious perturbations remain poorly understood. We applied a global analysis method to identify dynamically changing proteins within the burn environment, which could eventually become biomarkers or targets for treatment.

MATERIALS AND METHODS

Protein extracts of normal/unwounded skin and burn wounds were assayed by 2D-difference gel electrophoresis (DIGE), a proteomic technology by which abundance levels of intact proteins (including isoforms) were simultaneously quantified from multiple samples with statistical confidence. Through unsupervised multivariate principal component analysis, protein expression patterns from individual samples were appropriately clustered into their correct temporal healing periods grouped into postburn periods of 1-3 days, 4-6 days, or 7-10 days after injury. Forty-six proteins were subsequently selected for identification by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

RESULTS

Proteins identified with differential temporal patterns of expression included predictable cytoskeletal proteins such as vimentin, and keratins 1, 5, 6, 16, and 17. Other candidate proteins with potential involvement in healing included heat shock protein 90, members of the serpin family (Serpin B1, SCCA1 and -2), haptoglobin, gelsolin, eIF4A1, IQGAP1, and translationally controlled tumor protein.

CONCLUSIONS

We have used the combined technique, DIGE/mass spectrometry, to capture new insights into cutaneous responses to burn trauma and subsequent processes of early wound healing in humans. This pilot study provides a proteomic snapshot of temporal events that can be used to weave together the interconnected processes that define the response to serious cutaneous injury.