Elevation of plasma free PAI-1 levels as an integrated endothelial response to severe burns

Factor XIII in major burns coagulation

BACKGROUND

In the days following a burn injury, major burn patients (MBP) present a multifactorial coagulation disorder known as acute burn-induced coagulopathy. Several studies have investigated coagulation in MBPs; however, Factor XIII (FXIII), which converts fibrin monomers into a stable clot and promotes wound healing, has not yet been studied.

OBJECTIVE

To determine the kinetics of FXIII and other coagulation factors and cofactors in MBPs in order to clarify coagulopathy in these patients and its potential relationship with surgical bleeding.

METHODS

Prospective observational pilot study of the kinetics of FXIII and other coagulation factors and cofactors in MBPs during the first 30 days of burn injury.

RESULTS

FXIII levels show a significant decline of 75.10% in the interval between the burn injury and surgery, and a decline of 87.70% in the 24 h following surgery. Patients undergo surgery with a median antigenic FXIII of 32%. Plasma levels of most factors decrease significantly 24 h after the burn injury.

CONCLUSION

MBPs experience a significant decrease in plasma levels of FXIII from the time of admission up to 24 h after surgery. Abnormally low levels were observed at the time of surgery that could not be detected by other coagulation tests. The decrease in most factors at 24 h seems to be associated with dilution due to intensive fluid resuscitation.

Serum Plasminogen Activator Inhibitor-1, α 1-Acid Glycoprotein, C-Reactive Protein, and Platelet Factor 4 Levels-Promising Molecules That Can Complete the "Puzzle" of the Biochemical Milieu in Severe Burns: Preliminary Results of a Cohort Prospective Study

Background: Burns represent a serious health problem, associated with multiple-organ failure, prolonged hospitalization, septic complications, and increased rate of mortality. The main aim of our study was to evaluate the levels of various circulating molecules in children with severe burns (more than 25% TBSA), in three different moments: 48 h, day 10, and day 21 post-burn. Materials and Methods: This study included 32 children with burns produced by flame, hot liquid, and electric arc and 21 controls. Serum plasminogen activator inhibitor-1 (PAI-1), α 1-acid glycoprotein (AGP), C-reactive protein (CRP), and platelet factor 4 (PF4) were detected using the Multiplex technique. Several parameters, such as fibrinogen, leucocyte count, thrombocyte count, triiodothyronine, thyroxine, and thyroid-stimulating hormone were also determined for each patient during hospitalization. Results: Significant statistical differences were obtained for CRP, AGP, and PF4 compared to the control group, in different moments of measurements. Negative correlations between CRP, AGP, and PF4 serum levels and burned body surface, and also the hospitalization period, were observed. Discussions: CRP levels increased in the first 10 days after burn trauma and then decreased after day 21. Serum PAI-1 levels were higher immediately after the burn and started decreasing only after day 10 post-burn. AGP had elevated levels 48 h after the burn, then decreased at 7-10 days afterwards, and once again increased levels after 21 days. PF4 serum levels increased after day 10 since the burning event. Conclusions: Serum CRP, AGP, PAI-1, and PF4 seem to be promising molecules in monitoring patients with a burn within the first 21 days.

Coagulation Alterations in Major Burn Patients: A Narrative Review

Major burn patients (MBP) can present multifactorial coagulation alterations induced by trauma and endothelial damage, fluid replacement therapy, hypothermia, hypoperfusion, acidosis, and activation of the inflammatory cascade. However, the multiple coagulation alterations that occur are still poorly defined. The aim of this review is to combine the results of the different coagulation tests currently used to study coagulation changes in these patients. The PubMed database was searched for articles reporting factor levels or coagulation tests using the keywords "Burns" and "Blood Coagulation". Of the 720 articles retrieved from the search, 20 were finally included in the review. Coagulopathy in the MBP differs from that of the trauma patient, insofar as the former present with an increase in factors VIII, IX, and vW on admission accompanied by an increase in fibrin and thrombin production. This is followed by activation of fibrinolysis and prolonged prothrombin (PT) and thromboplastin (aPTT) times in the first 24 hours, increased fibrinogen after 48 hours, and thrombocytosis between the second and third week. Viscoelastic testing shows a pattern that shifts from normal coagulation to a hypercoagulable state with no evidence of hyperfibrinolysis. Alterations in PT and aPTT together with elevated Factor VIII have been associated with mortality, while normalization of antithrombin, and protein C and S levels are associated with a good prognosis. Although standard coagulation tests initially show alterations, the MBP does not appear to be hypocoagulable, and viscoelastic testing shows a trend toward hypercoagulability over time. Coagulation disorders affect prognosis in the MBP.

Burn-Induced Coagulopathies: a Comprehensive Review

Burn-induced coagulopathy is not well understood, and consensus on diagnosis, prevention, and treatments are lacking. In this review, literature on burn-induced (and associated) coagulopathy is presented along with the current understanding of the effects of burn injury on the interactions among coagulation, fibrinolysis, and inflammation in the acute resuscitative phase and reconstructive phase of care. The role of conventional tests of coagulopathy and functional assays like thromboelastography or thromboelastometry will also be discussed. Finally, reported methods for the prevention and treatment of complications related to burn-induced coagulopathy will be reviewed.

Early abnormal fibrinolysis and mortality in patients with thermal injury: a prospective cohort study

INTRODUCTION

Abnormal fibrinolysis early after injury has been associated with increased mortality in trauma patients, but no studies have addressed patients with burn injury. This prospective cohort study aimed to characterize fibrinolytic phenotypes in burn patients and to see if they were associated with mortality.

METHODS

Patients presenting to a regional burn centre within 4 h of thermal injury were included. Blood was collected for sequential viscoelastic measurements using thromboelastography (RapidTEG™) over 12 h. The percentage decrease in clot strength 30 min after the time of maximal clot strength (LY30) was used to categorize patients into hypofibrinolytic/fibrinolytic shutdown (SD), physiological (PHYS) and hyperfibrinolytic (HF) phenotypes. Injury characteristics, demographics and outcomes were compared.

RESULTS

Of 115 included patients, just over two thirds were male. Overall median age was 40 (i.q.r. 28-57) years and median total body surface area (TBSA) burn was 13 (i.q.r. 6-30) per cent. Some 42 (36.5 per cent) patients had severe burns affecting over 20 per cent TBSA. Overall mortality was 18.3 per cent. At admission 60.0 per cent were PHYS, 30.4 per cent were SD and 9.6 per cent HF. HF was associated with increased risk of mortality on admission (odds ratio 12.61 (95 per cent c.i. 1.12 to 142.57); P = 0.041) but not later during the admission when its incidence also decreased. Admission SD was not associated with mortality, but incidence increased and by 4 h and beyond, SD was associated with increased mortality, compared with PHYS (odds ratio 8.27 (95 per cent c.i. 1.16 to 58.95); P = 0.034).

DISCUSSION

Early abnormal fibrinolytic function is associated with mortality in burn patients.

Alcohol Intoxication and the Postburn Gastrointestinal Hormonal Response

Gastrointestinal hormones are essential in postburn metabolism. Since near 50% of burn victims test positive for blood alcohol levels at hospital admission and have inferior outcomes compared to nonintoxicated burn patients; we hypothesized that the gastrointestinal hormone secretion is compromised in intoxicated burn victims. To test our theory, we quantified gastrointestinal hormones serum levels in a combine ethanol intoxication and burn injury mouse model. Thus, mice received a daily dose of ethanol for 3 days, rested 4 days, and were given ethanol 3 additional days. Mice underwent 15% TBSA scald burn 30 minutes after their last ethanol dose. Serum samples were collected 24 hours after burn injury. Nonintoxicated burned mice exhibited an increase in glucose, insulin, ghrelin, plasminogen activator inhibitor-1, leptin, and resistin by 1.4-, 3-, 13.5-, 6.2-, 9.4-, and 2.4-fold, respectively, compared to sham vehicle mice (P < .05). Burn injury also reduced serum gastric inhibitory polypeptide (GIP) by 32% compared to sham-injured, vehicle-treated mice. Leptin, resistin, glucagon-like peptide-1, as well as insulin, were not different from sham groups when intoxication preceded burn injury. Nevertheless, in burned mice treated with ethanol, gastric inhibitory polypeptide and glucagon serum levels exhibited a significant fold increase of 3.5 and 4.7, respectively. With these results, we conclude that 24 hours after burn injury, mice developed significant changes in gastrointestinal hormones, along with hyperglycemia. Moreover, the combined insult of burn and ethanol intoxication led to additional hormonal changes that may be attributed to a potential pancreatic dysfunction. Further multiday studies are required to investigate the etiology, behavior, and clinical significance of these hormonal changes.

The procoagulant molecule plasminogen activator inhibitor-1 is associated with injury severity and shock in patients with and without traumatic brain injury

BACKGROUND

Traumatic injury is associated with an increased risk of coagulopathy and venous thrombosis. plasminogen activator inhibitor-1 (PAI-1) is a procoagulant molecule that inhibits tPA/uPA, thrombomodulin, and activated protein C. We hypothesized that elevated PAI-1 levels would be associated with increased Injury Severity Score (ISS) in injured patients with and without traumatic brain injury and that PAI-1 levels would vary with injury type.

METHODS

We retrospectively analyzed demographic, ISS, and hemodynamic data from a prospectively collected database. Patients with traumatic injury requiring intensive care unit admission (n = 268) were classified as multiple injuries, isolated body, or isolated head based on Abbreviated Injury Severity score. Admission PAI-1 levels were quantified using a Luminex analyte platform. Univariate tests for association informed the construction of a multivariate model of the relationship between PAI-1 and ISS.

RESULTS

Plasminogen activator inhibitor-1 positively associated with ISS (p < 0.0001) and was highest in patients with ISS greater than 35 (p < 0.0001). Plasminogen activator inhibitor-1 was significantly different between multiple injuries, isolated body, and isolated head patients (p < 0.0001). On univariate analysis, age (p = 0.0011), hypotension (p = 0.0076), and alcohol intoxication (p = 0.0024) were all positively associated with PAI-1 level. Admission international normalized ratio was not associated with PAI-1 level (p = 0.638). After adjusting for age, sex, hypotension, and alcohol intoxication, higher PAI-1 levels were associated with higher ISS (p < 0.0001).

CONCLUSION

Elevated PAI-1 at admission is associated with higher ISS. This association is more pronounced in patients with hypotension. These findings suggest that PAI-1 levels may reflect the burden of endothelial damage and platelet activation after injury.

LEVEL OF EVIDENCE

Prognostic, level III.

Transforming growth factor-β in stem cells and tissue homeostasis

TGF-β 1-3 are unique multi-functional growth factors that are only expressed in mammals, and mainly secreted and stored as a latent complex in the extracellular matrix (ECM). The biological functions of TGF-β in adults can only be delivered after ligand activation, mostly in response to environmental perturbations. Although involved in multiple biological and pathological processes of the human body, the exact roles of TGF-β in maintaining stem cells and tissue homeostasis have not been well-documented until recent advances, which delineate their functions in a given context. Our recent findings, along with data reported by others, have clearly shown that temporal and spatial activation of TGF-β is involved in the recruitment of stem/progenitor cell participation in tissue regeneration/remodeling process, whereas sustained abnormalities in TGF-β ligand activation, regardless of genetic or environmental origin, will inevitably disrupt the normal physiology and lead to pathobiology of major diseases. Modulation of TGF-β signaling with different approaches has proven effective pre-clinically in the treatment of multiple pathologies such as sclerosis/fibrosis, tumor metastasis, osteoarthritis, and immune disorders. Thus, further elucidation of the mechanisms by which TGF-β is activated in different tissues/organs and how targeted cells respond in a context-dependent way can likely be translated with clinical benefits in the management of a broad range of diseases with the involvement of TGF-β.

Analysis of factor XIa, factor IXa and tissue factor activity in burn patients

INTRODUCTION

An elevated procoagulant activity observed in trauma patients is, in part, related to tissue factor (TF) located on blood cells and microparticles. However, analysis of trauma patient plasma indicates that there are other contributor(s) to the procoagulant activity. We hypothesize that factor (F)XIa and FIXa are responsible for an additional procoagulant activity in burn patients.

METHODS

Multiple time-point plasma samples from 56 burn patients (total number of samples was 471; up to 20 time-points/patient collected in 3 weeks following admission) were evaluated in a thrombin generation assay using inhibitory antibodies to TF, FIXa and FXIa.

RESULTS

Due to the limited volume of some samples, not all were analyzed for all three proteins. At admission, 10 of 53 patients (19%) had active TF, 53 of 55 (96%) had FXIa and 48 of 55 (87%) had FIXa in their plasma. 34 patients of 56 enrolled (61%) showed TF activity at one or more time-points. All patients had FXIa and 96% had FIXa at one or more time-points. Overall, TF was observed in 99 of 455 samples analyzed (22%), FXIa in 424 of 471 (90%) and FIXa in 244 of 471 (52%). The concentration of TF was relatively low and varied between 0 and 2.1pM, whereas that of FXIa was higher, exceeding 100pM in some samples. The majority of samples with FIXa had it at sub-nanomolar concentrations. No TF, FXIa and FIXa activity was detected in plasma from healthy individuals.

CONCLUSIONS

For the first time reported, the majority of plasma samples from burn patients have active FXIa and FIXa, with a significant fraction of them having active TF. The concentration of all three proteins varies in a wide range.

Coagulopathy and its management in patients with severe burns

Severe burn injury is associated with systemic coagulopathy. The changes in coagulation described in patients with severe burns resemble those found patients with sepsis or major trauma. Coagulopathy in patients with severe burns is characterized by procoagulant changes, and impaired fibrinolytic and natural anticoagulation systems. Both the timing of onset and the severity of hemostatic derangements are related to the severity of the burn. The exact pathophysiology and time course of coagulopathy are uncertain, but, at least in part, result from hemodilution and hypothermia. As the occurrence of coagulopathy in patients with severe burns is associated with increased comorbidity and mortality, coagulopathy could be seen as a potential therapeutic target. Clear guidelines for the treatment of coagulopathy in patients with severe burns are lacking, but supportive measures and targeted treatments have been proposed. Supportive measures are aimed at avoiding preventable triggers such as tissue hypoperfusion caused by shock, or hemodilution and hypothermia following the usually aggressive fluid resuscitation in these patients. Suggested targeted treatments that could benefit patients with severe burns include systemic treatment with anticoagulants, but sufficient randomized controlled trial evidence is lacking.

Fibrinolysis is essential for fracture repair and prevention of heterotopic ossification

Bone formation during fracture repair inevitably initiates within or around extravascular deposits of a fibrin-rich matrix. In addition to a central role in hemostasis, fibrin is thought to enhance bone repair by supporting inflammatory and mesenchymal progenitor egress into the zone of injury. However, given that a failure of efficient fibrin clearance can impede normal wound repair, the precise contribution of fibrin to bone fracture repair, whether supportive or detrimental, is unknown. Here, we employed mice with genetically and pharmacologically imposed deficits in the fibrin precursor fibrinogen and fibrin-degrading plasminogen to explore the hypothesis that fibrin is vital to the initiation of fracture repair, but impaired fibrin clearance results in derangements in bone fracture repair. In contrast to our hypothesis, fibrin was entirely dispensable for long-bone fracture repair, as healing fractures in fibrinogen-deficient mice were indistinguishable from those in control animals. However, failure to clear fibrin from the fracture site in plasminogen-deficient mice severely impaired fracture vascularization, precluded bone union, and resulted in robust heterotopic ossification. Pharmacological fibrinogen depletion in plasminogen-deficient animals restored a normal pattern of fracture repair and substantially limited heterotopic ossification. Fibrin is therefore not essential for fracture repair, but inefficient fibrinolysis decreases endochondral angiogenesis and ossification, thereby inhibiting fracture repair.

Wood bark smoke induces lung and pleural plasminogen activator inhibitor 1 and stabilizes its mRNA in porcine lung cells

Although aberrant fibrinolysis and plasminogen activator inhibitor 1 (PAI-1) are implicated in acute lung injury, the role of this serpin in the pathogenesis of wood bark smoke (WBS)-induced acute lung injury (SIALI) and its regulation in resident lung cells after exposure to smoke are unclear. A total of 22 mechanically ventilated pigs were included in this study. Immunohistochemical analyses were used to assess fibrin and PAI-1 in the lungs of pigs with SIALI in situ. Plasminogen activator inhibitor 1 was measured in bronchoalveolar lavage fluids by Western blotting. Induction of PAI-1 was determined at the protein and mRNA levels by Western and polymerase chain reaction analyses in primary porcine alveolar type II cells, fibroblasts, and pleural mesothelial cells. Plasminogen activator inhibitor 1 mRNA stability was determined by transcription chase studies. Gel shift analyses were used to characterize the mechanism regulating PAI-1 mRNA stability. Smoke-induced ALI induced PAI-1, with prominent extravascular fibrin deposition in large and small airways as well as alveolar and subpleural compartments. In pleural mesothelial cells, lung fibroblasts, and alveolar type II cells, PAI-1 mRNA was stabilized by WBS extract and contributed to induction of PAI-1. The mechanism involves dissociation of a novel 6-phospho-d-gluconate-NADP oxidoreductase-like PAI-1 mRNA binding protein from PAI-1 mRNA. Exposure to WBS induces prominent airway and mesothelial expression of PAI-1, associated with florid distribution of fibrin in SIALI in vivo Wood bark smoke components induce PAI-1 in vitro in part by stabilization of PAI-1 mRNA, a newly recognized pathway that may promote extravascular fibrin deposition and lung dysfunction in SIALI.

Coagulation abnormalities following thermal injury

Changes in coagulation may have a profound impact on outcomes following severe burns and the coagulation abnormalities after thermal injury are incompletely described. We postulated that thermal injury induces a systemic hypercoagulable state. With Institutional Review Board approval, five patients were consented for enrollment in this case series. After obtaining informed consent, blood was drawn on hospital days 1, 2, 3, 5, and 7 or until discharge if discharge was in less than 7 days. Standard coagulation testing was performed, as well as a battery of sophisticated specialized coagulation assays. Other data collected includes fluid resuscitation volumes, pharmacologic interventions, and general physiologic information. Results (n = 5) demonstrate that burns less than 6% total body surface area appear to have little effect on coagulation. Burns greater than 6% appear to induce a systemic hypercoagulable state with a phase and magnitude relationship proportional to total body surface area burned. Severe burns greater than 40% appear to induce a consumptive coagulopathy. Prothrombin fragment 1.2 may represent a useful screening test for a burn-induced hypercoagulable state.

Longitudinal changes in plasma Transforming growth factor beta-1 and post-burn scarring in children

Transforming growth factor beta1, a multifunctional growth factor, plays a pivotal role in wound healing and has been shown to accelerate impaired wound healing. However, high systemic levels of Transforming growth factor beta1 have generally been associated with fibrotic disease processes such as myelofibrosis and pulmonary fibrosis. Hypertrophic scarring occurring during childhood interferes with growth, impairs the function and causes immense psychological and aesthetic problems. Burns is the leading cause of hypertrophic scarring. We studied the longitudinal relationship between plasma Transforming growth factor beta-1 and post-burn wound healing and scarring in children. We discovered that the plasma levels of Transforming growth factor beta-1 rapidly increased to significantly higher levels in the first two weeks post-injury and fell thereafter, in patients who healed with good quality scars post-burn. By contrast, the increase in plasma TGFbeta1 levels in the early stages after-burn, was noticeably absent in patients who developed hypertrophic scarring. We propose that this change in the systemic levels of TGFbeta1 early after the burn may be used as an indicator of patients at risk of developing hypertrophic burn scars. This group of patients could then be targeted for early pharmacological/physical interventions to reduce/prevent scar-related morbidity in burn survivors.

In vitro and in vivo evidence for shear-induced activation of latent transforming growth factor-beta1

Transforming growth factor-beta1 (TGF-beta1) has potent physiologic and pathologic effects on a variety of cell types at subnanomolar concentrations. Platelets contain 40 times as much TGF-beta1 as other cells and secrete it as an inactive (latent) form in complex with latency-associated peptide (LAP), which is disulfide bonded via Cys33 to latent TGF-beta binding protein 1 (LTBP-1). Little is known about how latent TGF-beta1 becomes activated in vivo. Here we show that TGF-beta1 released from platelets or fibroblasts undergoes dramatic activation when subjected to stirring or shear forces, providing a potential mechanism for physiologic control. Thiol-disulfide exchange appears to contribute to the process based on the effects of thiol-reactive reagents and differences in thiol labeling of TGF-beta1 before and after stirring or shear. Activation required the presence of LTBP, as TGF-beta1 contained in complex with only LAP could not be activated by stirring when studied as either a recombinant purified protein complex or in the platelet releasates or sera of mice engineered to contain an LAP C33S mutation. Release and activation of latent TGF-beta1 in vivo was demonstrated in a mouse model 5 minutes after thrombus formation. These data potentially provide a novel mechanism for in vivo activation of TGF-beta1.

Combined anticoagulants ameliorate acute lung injury in sheep after burn and smoke inhalation

Burn and smoke inhalation-related multiple organ dysfunction is associated with a severe fall in the plasma concentration of antithrombin. Therefore the aim of the present study was to test the hypothesis that intravenous administration of recombinant human antithrombin in combination with aerosolized heparin will ameliorate acute lung injury in sheep exposed to cutaneous burn and smoke inhalation. Sheep were prepared operatively for study and, 7 days post-surgery, sheep were given a cutaneous burn (40% of total body surface area, third-degree burn) and insufflated with cotton smoke (48 breaths, <40 degrees C) under halothane anaesthesia. After injury, sheep were placed on a ventilator and resuscitated with Ringer's lactate solution. The animals were divided into three groups: sham group (non-injured and non-treated; n=6), saline group (injured and received saline; n=6) and rhAT.iv.+Hep group [injured and treated with rhAT (recombinant human antithrombin) and heparin; n=6]. In the rhAT.iv.+Hep group, rhAT was infused continuously for 48 h starting 1 h post-injury with a dose of 0.34 mg.h(-1).kg(-1) of body weight and heparin (10000 units) was aerosolized every 4 h starting at 1 h post-injury. The experiment lasted 48 h. Haemodynamics were stable in sham group, whereas the saline-treated sheep developed multiple signs of acute lung injury, including decreased pulmonary gas exchange, increased inspiratory pressures, extensive airway obstruction and increased pulmonary oedema. These pathological changes were associated with a severe fall in plasma antithrombin concentration, lung tissue accumulation of leucocytes and excessive production of NO. Treatment of injured sheep with anticoagulants attenuated all of the pulmonary pathophysiology observed. In conclusion, the results provide definitive evidence that anticoagulant therapy may be a novel and effective treatment tool in the management of burn patients with concomitant smoke inhalation injury.

Early coagulation disorders after severe burn injury: impact on mortality

OBJECTIVE

To evaluate the time course of coagulation markers in the early postburn period and clarify the role of coagulation alterations in organ failure and in mortality prognosis.

DESIGN AND SETTING

This prospective study was conducted in the burn ICU of a tertiary hospital.

PATIENTS

45 patients with severe thermal burn injury.

MEASUREMENTS AND RESULTS

Clinical data and coagulation and fibrinolysis parameters were measured during the first postburn week. The ICU 28-day mortality rate was 33%. Significant differences in the time course of coagulation markers were observed between survivors and nonsurvivors. SOFA score distinguished between patients with overt and nonovert disseminated intravascular coagulation (DIC) during the overall investigation period. Presence of overt DIC was related to mortality (OR=0.1). Antithrombin, protein S, plasminogen activator inhibitor 1, and SOFA score on day 3, protein C on day 5, and thrombin/antithrombin complexes on day 7 revealed a good prognostic value for ICU mortality, according to the area under ROC curves.

CONCLUSIONS

Severe thermal injury is associated with the early activation of coagulation cascade, presence of DIC, organ failure, and increased mortality.

Burn injuries

PURPOSE OF REVIEW

To summarize new advances and research findings that relate to the treatment of burn victims.

RECENT FINDINGS

Recent advances in burn resuscitation and critical care reflect a better understanding of the acute phase pathophysiology of severe burns. Aggressive management of the unstable burn airway is always the most important clinical priority. Emphasis has been placed on the early identification of inhalation injury and its impact on fluid resuscitation, as well as on a protective lung strategy to reduce the development of pulmonary edema, acute lung injury and pneumonia, and to reduce the risk of barotrauma. New blood markers, such as serum cholinesterase and inflammatory cytokines, have been introduced to assist in the prognosis of morbidity and mortality, beyond the traditional vital signs. At this time, however, these are available only for research purposes. Finally, early burn wound excision and coverage with new biodegradable materials results in less pain and more rapid healing for the patient.

SUMMARY

The combination of innovative approaches and a dedicated burn team is expected to continue to improve survival in the next few years even in the most severe cases.

Transforming growth factor-beta3 affects plasminogen activator inhibitor-1 expression in fetal mice and modulates fibroblast-mediated collagen gel contraction

For over two decades, the precise role of transforming growth factor-beta (TGF-beta) isoforms in scarless healing of mammalian fetal skin wounds has generated much interest. Although their exact role remains to be established, it has been suggested that high TGF-beta3 activity may correlate with a scarless phenotype. Previously, we showed that plasminogen activator inhibitor-1 (PAI-1), a known TGF-beta downstream molecule and marker of fibrosis, is also developmentally regulated during fetal skin development. In this study, the relationship between TGF-beta3 and PAI-1 was investigated using embryonic day 14.5 TGF-beta3 knockout (ko) mice. The results showed increased PAI-1 expression in the epidermis and dermis of ko mice, using an ex vivo limb-wounding study. Furthermore, increased PAI-1 expression and activity was seen in embryo extracts and conditioned media of ko dermal fibroblasts. When TGF-beta3 knockout fibroblasts were placed into three-dimensional collagen matrices, they were found to have decreased collagen gel contraction, suggesting altered cell-matrix interaction. These findings provide a further avenue for the interactive role of TGF-beta3 and PAI-1 during fetal scarless repair.

Prévention de la maladie thromboembolique veineuse chez le brûlé

Few studies deal with thromboembolic complications in burn patients. The review of the literature and current practice in burn centres point out low, average and high-risk patients, according to the characteristics of the burns wounds. In case of average risk, low molecular weight heparin prophylaxis is suggested. In high risk patients, low molecular weight heparin therapy or continuous intravenous heparin are recommended. This prevention should be continued until the recovery of a normal mobility and complete resolution of inflammation.

Endothelial thrombomodulin (CD 141) in a rabbit burn model

Thrombomodulin (CD 141) is an endothelial surface transmembrane glycoprotein. It is involved in the activation of protein C in the inactivation of thrombin. In severe sepsis CD 141 is shed from the endothelial surface. This leads to disseminated intravascular coagulation (DIC), disturbed organ functions and multi organ failure (MOF). In this study, we investigated if endothelial bound thrombomodulin is shed in thermal injuries.

MATERIAL AND METHODS

In 10 New Zealand white rabbits full thickness and superficial partial thickness burns were produced. Dermal blood flow was analyzed by measuring the fluorescence of intravenously injected indocyanine green. Skin-biopsies were taken from the burn wounds from the zones of stasis between full thickness burns and from unburned skin 72 h post burn. Specimens were processed for immunoperoxidase staining using a specific monoclonal antibody against CD 141.

RESULTS

Dermal blood flow was reduced in burned skin areas and in the zones of stasis. Thrombomodulin was only detectable on the surface of capillary endothelial cells in specimens taken from unburned skin areas. No thrombomodulin was detectable in specimens taken from burn wounds or from the zones of stasis. Thus, shedding of thrombomodulin was detectable in areas with reduced dermal blood flow.

CONCLUSION

Thermal injuries affect the dermal endothelial surfaces resulting in a shedding of thrombomodulin. This mechanism might be involved in the development of progressive skin damage in the zone of stasis. Disseminated intravascular coagulation following inactivation of thrombomodulin might lead to multiple organ dysfunctions in severe burn injuries.

The role of plasminogen activator inhibitor type 1 in the inflammatory response to local tissue injury

BACKGROUND

The plasma levels of the plasminogen activator-inhibitor type 1 (PAI-1) are consistently elevated in patients with sterile tissue injury, often accompanied by a systemic acute phase protein response. It remains unknown, however, whether and to what extent PAI-1 affects the host response to trauma.

METHODS AND RESULTS

By using the well-established murine model of turpentine-induced tissue injury we compared local and systemic inflammatory responses in PAI-1 gene-deficient (PAI-1-/-) and normal wild-type (Wt) mice. Subcutaneous turpentine injection elicited strong increases in PAI-1 protein concentration in plasma and at the site of injury, but not in liver. PAI-1 mRNA was locally increased and expressed mainly by macrophages and endothelial cells. PAI-1 deficiency greatly enhanced the early influx of neutrophils to the site of inflammation, which was associated with increased edema and necrosis at 8 h after injection. Furthermore, PAI-1-/- mice showed a reduced early interleukin (IL)-6 induction with subsequently lower acute phase protein levels and a much slower recovery of body weight loss.

CONCLUSION

These findings suggest that PAI-1 is not merely a marker of tissue injury but plays a functional role in the local and systemic host response to trauma.

Plasminogen Activator Inhibitor-1 4G Allele in the 4G/5G Promoter Polymorphism Increases the Occurrence of Cerebral Ischemia After Aneurysmal Subarachnoid Hemorrhage

BACKGROUND AND PURPOSE

In several acute life-threatening diseases, the 4G-allele in the 4G/5G-promotor polymorphism in the plasminogen activator inhibitor-1 (PAI-1) gene is associated with higher PAI-1 levels and increased poor outcome, probably by promoting the formation of microthrombi. The aim of the present study was to investigate whether the PAI-1 4G/5G polymorphism is associated with the occurrence of cerebral ischemia, rebleeding, and other events, and clinical outcome after aneurysmal subarachnoid hemorrhage.

METHODS

DNA was collected and analyzed in 126 patients with aneurysmal subarachnoid hemorrhage admitted to the Academic Medical Centre Amsterdam and University Medical Centre Utrecht in the Netherlands. All episodes of deterioration were classified according to predefined criteria. Causes of poor outcome and functional outcome were assessed 3 months after the initial bleeding according to the 5-point Glasgow Outcome Scale (GOS).

RESULTS

Secondary ischemia occurred more often in patients with the 4G genotype than in patients homozygous for the 5G allele (RR: 3.3; 95% CI: 1.1 to 10.0). No significant differences were found between the groups for rebleeding or other events. Patients with the 4G genotype tended to have a higher risk for poor outcome than patients with the 5G/5G genotype (RR 1.2; 95% CI 0.7 to 2.2).

CONCLUSIONS

The 4G allele in the PAI-1 gene increases the risk for cerebral ischemia after aneurysmal subarachnoid hemorrhage (SAH) and probably also the risk for poor outcome. After early aneurysm occlusion, treatment aimed at enhancing fibrinolysis might be effective to prevent and treat cerebral ischemia in patients with aneurysmal SAH.

Plasminogen activators in inflammation and sepsis

Mortality of severe sepsis remains at 40% to 50%. Intensive efforts over the past two decades have only marginally improved outcome. Improving outcome in sepsis depends on understanding its pathophysiology, which involves triggers, responses of the organism, and dysfunction. Stress, injury, or infection trigger host responses, including local and systemic orchestrated mechanisms. Dysfunction and outcome depend on both trigger and response. Blood coagulation, inflammation, immunity, and fibrinolysis are critical components of the organism's responses. Understanding their role in sepsis pathophysiology is the key to effective treatment. Relevant studies were identified by a systematic literature search, complemented by manual search of individual citations. Using PubMed, 'sepsis' yields more than 62,000 references, 'plasminogen activators' more than 21,000. The selection of citations was guided by preference for reviews that expand important threads of argumentation. Single original studies were included when relevant to critical points. This analytical review describes the essential elements of pathophysiology and the current status of sepsis treatment. Based on this context, an emerging therapeutic option will be discussed: plasminogen activators.

Correlation between QT dispersion and burn severity

QT dispersion, defined as the maximal-minus-minimal QT interval on a 12-lead electrocardiogram, has emerged as a non-invasive measurement for quantifying the spatial inhomogeneity of ventricular repolarization under various conditions, including acute stress. Because burn injuries elicit acute stress reactions, it was hypothesized that QT dispersion increases with the severity of the burn injury. To test the hypothesis, 13 burned patients (age range of 22-76 years, nine males, ranging from 4.0 to 75.0% of total body surface area burned) in whom a measurable 12-lead electrocardiogram had been obtained within 4h after arrival at the emergency department were identified retrospectively, and their QTc intervals, i.e. QT intervals corrected for heart rate by the standard Bazett formula, were measured. QTc dispersion (QTcd) was then calculated, and correlations were assessed with burn severity (burn index, BI; prognostic burn index, PBI). Of the 13 patients, nine patients had a prolonged QTcd (>40 ms), and linear correlation analyses showed significant positive correlations between QTcd and both BI and PBI (r=0.61 and 0.62, respectively). In conclusion, QT dispersion was greater in the burned patients, and although the pathophysiology was unclear from the present study, the findings suggested that acute stress contributed to the spatial inhomogeneity of ventricular repolarization.