Changes in levels of serum IL-8 in burned patients

Biomarkers of sepsis in burn injury: an update

Sepsis, a dysregulated response to infection, is a leading cause of death after burn injury. Changes in the immune response as well as the loss of the skin, the primary barrier to infection, contribute to the increased risk for infection and sepsis in burn patients. This higher risk is further compounded by the development of the systemic inflammatory response and hypermetabolic state, which limit the utility of commonly used infection markers. As such, the development of sepsis biomarkers after burn injury is an imperative. A sepsis biomarker would facilitate earlier diagnosis and treatment of sepsis, thus decreasing length of stay, morbidity, and mortality after burn injury. Numerous different biomarkers, ranging from acute phase reactants, cytokines, and inflammatory markers to omics analyses and extracellular vesicles have been assessed as potential biomarkers in burn sepsis. To date no single biomarker has proven useful as the sole indicator for sepsis. The future of burn sepsis biomarkers will likely require a panel of biomarkers from all categories. The purpose of this review article is to list the various biomarkers that have been studied in burn sepsis and describe their clinical utility and future use in patients with burn injury.

The dynamic changes of monocytes and cytokines during wound healing post-burn injury

BACKGROUND

Burn injury is a sudden and traumatic injury that affects a large part of the population worldwide, who are placed at high risk of developing hypertrophic scars (HTS). HTS are a fibrotic scar resulting in painful contracted and raised scarring, affecting mobility in joints and work life, as well as cosmetically. The aim of this research was to enhance our understanding of the systematic response of monocytes and cytokines in wound healing after burn injury, in order to develop novel approaches to prevention and treatment of HTS.

METHODS

Twenty-seven burn patients and thirteen healthy individuals were recruited in this study. Burn patients were stratified by burn total body surface area (TBSA). Peripheral blood samples were taken post-burn injury. Serum and peripheral blood mononuclear cells (PBMCs) were separated from the blood samples. This research investigated cytokines IL-6, IL-8, IL1RA, IL-10, and chemokine pathways SDF-1/CXCR4, MCP-1/CCR2, RANTES/CCR5 during the wound healing process in burn patients with varying severity of injuries by using enzyme-linked immunosorbent assays. PBMCs were stained for monocytes and the chemokine receptors by flow cytometry. Statistical analysis was done by one-way ANOVA with a Tukey correction, and regression analysis was performed using Pearson's Correlation analysis.

RESULTS

The CD14⁺CD16^- monocyte subpopulation is larger in patients who developed HTS at 4-7 days. The CD14⁺CD16⁺ monocyte subpopulation is smaller in the first week of injury, where it is similar after 8 days. Burn injury increased CXCR4, CCR2, and CCR5 expressions in CD14⁺ CD16⁺ monocytes. Increases in MCP-1 at 0-3 days after burn injury was positively correlated with burn severity. IL-6, IL-8, RANTES, and MCP-1 significantly increased with increasing burn severity.

CONCLUSIONS

Monocytes and their chemokine receptors, as well as systemic levels of cytokines in wound healing of burn patients and scar development will require ongoing assessment to enhance our understanding of the abnormal wound healing after burn injury.

A 3D In Vitro Model for Burn Wounds: Monitoring of Regeneration on the Epidermal Level

Burns affect millions every year and a model to mimic the pathophysiology of such injuries in detail is required to better understand regeneration. The current gold standard for studying burn wounds are animal models, which are under criticism due to ethical considerations and a limited predictiveness. Here, we present a three-dimensional burn model, based on an open-source model, to monitor wound healing on the epidermal level. Skin equivalents were burned, using a preheated metal cylinder. The healing process was monitored regarding histomorphology, metabolic changes, inflammatory response and reepithelialization for 14 days. During this time, the wound size decreased from 25% to 5% of the model area and the inflammatory response (IL-1β, IL-6 and IL-8) showed a comparable course to wounding and healing in vivo. Additionally, the topical application of 5% dexpanthenol enhanced tissue morphology and the number of proliferative keratinocytes in the newly formed epidermis, but did not influence the overall reepithelialization rate. In summary, the model showed a comparable healing process to in vivo, and thus, offers the opportunity to better understand the physiology of thermal burn wound healing on the keratinocyte level.

Soluble Suppression Of Tumorigenicity-2 Predicts Hospital Mortality in Burn Patients: An Observational Prospective Cohort Pilot Study

BACKGROUND

The IL33/ST2 pathway has been implicated in the pathogenesis of different inflammatory diseases. Our aim was to analyze whether plasma levels of biomarkers involved in the IL33/ST2 axis might help to predict mortality in burn patients.

METHODS

Single-center prospective observational cohort pilot study performed at the Burns Unit of the Plastic and Reconstructive Surgery Department of the Vall d'Hebron University Hospital (Barcelona). All patients aged ≥18 years old with second or third-degree burns requiring admission to the Burns Unit were considered for inclusion. Blood samples were taken to measure levels of interleukins (IL)6, IL8, IL33, and soluble suppression of tumorigenicity-2 (sST2) within 24 h of admission to the Burns Unit and at day 3. Results are expressed as medians and interquartile ranges or as frequencies and percentages.

RESULTS

Sixty-nine patients (58 [84.1%] male, mean age 52 [35-63] years, total body surface area burned 21% [13%-30%], Abbreviated Burn Severity Index 6 [4-8]) were included. Thirteen (18.8%) finally died in the Burns Unit. Plasma levels of sST2 measured at day 3 after admission demonstrated the best prediction accuracy for survival (area under the receiver-operating curve 0.85 [0.71-0.99]; P < 0.001). The best cutoff point for the area under the receiver-operating curve index was estimated to be 2,561. In the Cox proportional hazards model, after adjusting for potential confounding, a plasma sST2 level ≥2,561 measured at day 3 was significantly associated with mortality (hazard ratio 6.94 [1.73-27.74]; P = 0.006).

CONCLUSIONS

Plasma sST2 at day 3 predicts hospital mortality in burn patients.

Increased serum concentrations of soluble ST2 predict mortality after burn injury

Background:

Large burn injuries induce a systemic response in affected patients. Soluble ST2 (sST2) acts as a decoy receptor for interleukin-33 (IL-33) and has immunosuppressive effects. sST2 has been described previously as a prognostic serum marker. Our aim was to evaluate serum concentrations of sST2 and IL-33 after thermal injury and elucidate whether sST2 is associated with mortality in these patients.

Methods:

We included 32 burn patients (total body surface area [TBSA] >10%) admitted to our burn intensive care unit and compared them to eight healthy probands. Serum concentrations of sST2 and IL-33 were measured serially using an enzyme-linked immunosorbent assay (ELISA) technique.

Results:

The mean TBSA was 32.5%±19.6%. Six patients (18.8%) died during the hospital stay. Serum analyses showed significantly increased concentrations of sST2 and reduced concentrations of IL-33 in burn patients compared to healthy controls. In our study cohort, higher serum concentrations of sST2 were a strong independent predictor of mortality.

Conclusions:

Burn injuries cause an increment of sST2 serum concentrations with a concomitant reduction of IL-33. Higher concentrations of sST2 are associated with increased in-hospital mortality in burn patients.

Blockade of IgM-Mediated Inflammation Alters Wound Progression in a Swine Model of Partial-Thickness Burn

In a mouse model, a second-degree burn elicits a severe inflammatory response that is mediated by circulating autoantibody specific for a neoantigen (nonmuscle myosin). Nonmuscle myosin is expressed by injured tissue, leading to amplified ulceration and scarring. We hypothesize that a synthetic peptide (N2) can mimic the neoantigen and competitively inhibit the autoantibody, decreasing inflammation, and reducing the extent of burn injury in a preclinical swine model of burn. Second-degree burns were created on young swine using brass cylinders, warmed to varying temperatures before skin contact. Animals were treated in double-blind fashion with normal saline, control peptide, or blocking peptide. Biopsies were taken at 2 hours, 1, 4, 7, and 14 days after burn injury. Burn wound healing parameters were assessed. Immunohistochemical staining for Ki-67, immunoglobulin (Ig)M, and interleukin (IL)-8 were also performed. N2 blocking peptide administration decreased dermal injury at 4 days with increased reepithelization, indicating more rapid healing. N2 normalized skin histology by 14 days and showed improved epidermal healing. Granulation tissue thickness was decreased, and there was an accompanying decrease in neutrophil infiltration. The basal layer of epidermis in N2-treated animals displayed more cells positive for Ki-67, suggesting a prompter regenerative capacity. Immunohistochemical staining demonstrated decreased deposition of immunoglobulin M and interleukin-8 after thermal injury in animals treated with N2 peptide, in comparison to controls. The findings of this study identify N2 blocking a specific inflammatory pathway, as a novel therapeutic approach, preventing the evolution of cutaneous burn injuries in a preclinical animal model.

Predicting and managing sepsis in burn patients: current perspectives

Modern burn care has led to unprecedented survival rates in burn patients whose injuries were fatal a few decades ago. Along with improved survival, new challenges have emerged in the management of burn patients. Infections top the list of the most common complication after burns, and sepsis is the leading cause of death in both adult and pediatric burn patients. The diagnosis and management of sepsis in burns is complex as a tremendous hypermetabolic response secondary to burn injury can be superimposed on systemic infection, leading to organ dysfunction. The management of a septic burn patient represents a challenging scenario that is commonly encountered by providers caring for burn patients despite preventive efforts. Here, we discuss the current perspectives in the diagnosis and treatment of sepsis and septic shock in burn patients.

Can leukocyte antisedimentation rate (LAR) predict septic complications and critical care survival early in polytrauma and burn victims?

BACKGROUND

In polytrauma and burn injury Systemic Inflammatory Response Syndrome (SIRS) develops. SIRS is presented in many hospitalized patients, including those who never develop infection or sepsis. Both in SIRS and sepsis the leukocyte activation occurs. In acute phase reaction leukocytes' upward flotation i.e. leukocyte antisedimentation rate (LAR) can indicate infectious origin.

OBJECTIVE

To evaluate the predictive power of LAR, serum C-reactive protein (CRP) and procalcitonin (PCT) levels regarding mortality risk and development of septic complications.

METHODS

In a prospective, observational study, 36 patients were followed for 5 days (T1-T5) after admission to a critical care unit immediately with severe polytrauma or burn injury. Eleven patients developed septic complications, their LAR, CRP and PCT levels were analyzed before and after 3 days of sepsis was declared.

RESULTS

Ten patients died due to septic complications. In survivors LAR at T1 (p < 0.001) and T2 (p < 0.001) as well as CRP at T1 (p < 0.05) were significantly higher compared to controls and non survivors. In septic patients LAR (p < 0.05) and CRP (p < 0.05) showed a significant drop one day before sepsis was declared. PCT levels failed to predict this.

CONCLUSIONS

Drop in LAR and CRP levels may be warning signs regarding the onset of septic complications after severe polytrauma and burn injury.

Effects of fluid resuscitation methods on the pro- and anti-inflammatory cytokines and expression of adhesion molecules after burn injury

Fluid resuscitation management can influence inflammatory response after burn injury. The aim of this study was to analyze the effects of two fluid resuscitation methods on the cytokine production and on the expression of the leukocyte surface markers. Thirty patients were included in this prospective randomized study with burn injury affecting more than 20% of the body surface area. Fluid resuscitation was guided by hourly urine output (HUO, n = 15) or by intrathoracic blood volume index (ITBVI, n = 15). Blood samples were taken on admission and on the next five consecutive mornings. Concentrations of interleukin (IL)-1beta, IL-6, IL-8, IL-10, IL-12p70, and tumor necrosis factor-alpha were measured in phorbol myristate acetate-stimulated and -nonstimulated samples. Leukocyte surface marker expressions (CD11a, CD11b, CD14, CD18, CD49d, and CD97) were also determined. In the ITBVI group, IL-6 levels on days 2 to 3 and IL-6/IL-10 ratios on days 2 to 3, and the IL-8/IL-10 ratios on days 3 to 5 were significantly higher than those in HUO group (P < .05). In the HUO group, IL-10 levels were significantly higher (P < .05) on days 4 and 5. Granulocyte CD11a levels on day 2, CD11b levels on days 4 to 6, lymphocyte CD11a on days 5 to 6, CD11b on days 3 to 6, CD49d on days 2 to 6, CD97 on day 6, monocyte CD11a, CD11b, CD18 levels on days 4 to 6, and CD14 levels on days 3 to 5 were significantly higher in the HUO group (P < .05). Our study suggests that ITBVI-guided fluid resuscitation of burned patients suppresses the shift toward anti-inflammatory imbalance and the expression of leukocyte surface markers more than HUO-guided resuscitation.

Burn trauma induces early HMGB1 release in patients: its correlation with cytokines

High-mobility group box protein 1 (HMGB1) is a nuclear protein that may be released actively from monocytes and macrophages or passively from necrotic or damaged cells. Several experimental data suggest that burn injury is accompanied by elevated plasma HMGB, but there are only few data available about its changes in burned patients. The aim of this study was to follow the time course and the prognostic value of plasma HMGB1 and cytokine changes in patients with severe burn injury affecting more than 10% of body surface area (n = 26). Blood samples were taken on admission and on the following 5 days. Plasma HMGB1 concentration was measured by the enzyme-linked immunosorbent assay method, whereas IL-6, IL-8, and IL-10 were assayed by the cytometric bead array kit. The HMGB1 and IL-10 concentrations were elevated on admission and gradually decreased thereafter. Significant differences were observed between survivors and nonsurvivors in HMGB1 (P < 0.01) and IL-10 (P < 0.001) concentrations on admission with higher levels in nonsurvivors. IL-6 and IL-8 started to increase markedly from day 2. Positive correlation (r = 0.669, P < 0.01) was found between burned body surface and HMGB1 on admission. Receiver operating characteristic analysis of data on admission showed that at a level of 16 ng/mL, HMGB1 indicated lethality, with 75.0% sensitivity and 85.7% specificity. Using the cutoff level of 14 pg/mL, IL-10 predicted intensive care unit mortality, with 85.7% sensitivity and 84.2% specificity. Very early HMGB1 and IL-10 release may have an important impact on the immune function of patients after burn trauma.

Metabolic response to injury and role of anabolic hormones

PURPOSE OF REVIEW

To provide a short review of the literature describing the hypermetabolic response to injury and potential treatments. Associated findings include changes in inflammatory mediators and secreted hormones.

RECENT FINDINGS

Treatments should be aimed at decreasing the response and potentially the use of anabolic agents. Of note, recent interest in the hyperglycemic response to injury and insulin treatment will be highlighted.

SUMMARY

The current metabolic care of the burned patient including nutrition is now being unfolded. It is relatively clear that anabolic treatment should be considered in all those with severe injury. Timing of the treatment, however, is still a topic of discussion.

Serum Levels of Prolactin, Growth Hormone, and Cortisol in Burn Patients: Correlations with Severity of Burn, Serum Cytokine Levels, and Fatality

In this study, we measured serum prolactin (PRL), cortisol, growth hormone, interleukin (IL)-1beta, IL-6, IL-8, IL-10, IL-12, and tumor necrosis factor-alpha in patients admitted with small-to-moderate burn injuries. Serum samples were obtained at the time of admission from 49 adult male burn patients with ages ranging from 18 to 91 years and TBSA ranging from 0.001 to 60%. The levels of serum PRL, IL-8, IL-6, and IL-1beta correlated positively with the TBSA, whereas only serum IL-8 levels correlated positively with fatality. Each of these factors were increased at least 2-fold at the higher burn severity. Not surprisingly, there was a large degree of variability in the hormone and cytokine levels in this patient population, which presumably reflects individual levels of stress, as well as other physiological variables. We also studied relationships between serum hormone levels and serum cytokine levels in this context. Linear regression analysis revealed a significant positive correlation between the serum PRL level and the levels of IL-10, IL-6, and IL-8. These results indicate that PRL responds to burn injury at early time points and that a subset of cytokines are involved in the early response to burn injury.

Cytokine response to diabetic ketoacidosis and its treatment

The objectives of this study were to monitor plasma cytokines as markers of cellular activation and as potential markers for the progression of the acute complications of diabetic ketoacidosis (DKA). Blood samples were obtained prior to, during and after treatment of severe DKA (pH < 7.2) in six children and adolescents. Plasma IL-10, IL-1beta, TNF-alpha, IL-6, IL-8 and IL-2 cytokine levels were assayed by ELISA at each of the time points. Prior to treatment, elevations of multiple cytokines were found, the highest being IL-10. Treatment of DKA resulted in a significant decrease of IL-10 at 6-8 h (p = 0.0062), and further increases in the inflammatory cytokines at 6-8 h and/or 24 h vs 120 h (baseline): IL-1beta (p =.0048); TNF-alpha (p =.0188) and IL-8 (p =.0048). This study strengthens the hypothesis that the metabolic crisis of DKA, and its treatment, have differential effects on cellular activation and cytokine release. The time frame for the increase in inflammatory cytokines correlates with the reported progression of subclinical brain edema, interstitial pulmonary edema and the development of clinical brain edema.

Deficient transforming growth factor beta and interleukin-10 responses contribute to the septic death of burned patients

In order to understand the roles of pro-inflammatory and anti-inflammatory cytokines in burn injury and sepsis post-burn, serial changes in serum levels of transforming growth factor beta-1 (TGF-beta-1) were determined and compared to those of IL-6 and IL-10 in 15 burned patients. Among these 15 patients, 8 recovered without sepsis. The other seven, who were septic, expired. Our results showed that an initial peak serum TGF-beta-1 response was detected within 1 day post-burn. Peak serum IL-6 and IL-10 responses were also detected within 4 days after the burn injury of these patients. Significant differences in peak serum IL-6, IL-10 and TGF-beta-1 levels were not found between patients with total body surface area (TBSA) of greater or less than 50% and between patients who survived or expired from burn injury. Afterwards, levels of circulating IL-6 and IL-10 remained low in the survivors. However, a second peak response in serum TGF-beta-1 levels was observed in all burned patients analyzed. The second peak serum TGF-beta-1 levels post-burn of the eight survivors and the seven non-survivors were from 28,542 to 76,554 pg/ml (a mean value of 51,256+/-14,264 pg/ml) and from 8616 to 40,851 pg/ml (a mean value of 24,079+/-10,399 pg/ml), respectively. A significant difference (P<0.01) in mean values of the second peak TGF-beta-1 responses between groups of survivors and non-survivors was detected. Levels of circulating IL-6 in the septic non-surviving patients showed a tendency to increase 1-2 weeks post-burn and reached high levels before the expiration of these patients. After an initial peak response, the serum IL-10 level remained low in one of the seven non-survivors, while it increased in the other six non-survivors. However, marked increases in circulating IL-10 levels were observed only just before the death of these non-survivors. In conclusion, an initial increase in serum levels of IL-6, IL-10 and TGF-beta-1 was detected post-burn. A marked increase in serum levels of IL-6 before death suggests its role in the pathophysiology of sepsis in burned patients. In addition, a low secondary TGF-beta-1 response and a lack and/or delay in the increase of circulating IL-10 in the non-survivors may all contribute to the pathophysiology of septic death in burned patients.

Changes in circulating levels of an anti-inflammatory cytokine interleukin 10 in burned patients

In order to understand the role of an anti-inflammatory cytokine interleukin 10 (IL-10) in the pathophysiology of burn injury, IL-10 levels in serial serum samples of 22 burned patients were analyzed. The total body surface areas (TBSA) of the burn injury ranged from 30 to 90%. Among these 22 patients, 14 recovered and the other eight, who were septic, expired. A significant difference in serum IL-10 values on admission (5-20 h postburn) was found (P<0.05) between patients who survived or died from burn injury as analyzed by the Student's t test. In addition, a significant difference in serum IL-10 on admission was also found (P<0.05) between patients with TBSA of greater or less than 50%. An initial peak serum IL-10 response was detected within 2.5 days postburn. Significant differences in the peak serum IL-10 levels were not found between patients with TBSA of greater or less than 50% and patients who survived or expired from burn injury. Afterwards, serum IL-10 remained low in the survivors, while an increase in serum IL-10 could be detected in the non-survivors with proven sepsis. Levels of circulating IL-6 in these non-surviving patients showed a tendency to increase starting from about 1-2 weeks postburn which coincided temporally with the detection of infections. However, marked increases in circulating IL-10 levels were observed just before death in four of the eight non-survivors. The serum samples of these four patients were collected at 31 h (404.8 pg/ml), 2 h (773.9 pg/ml), 5 days (150.7 pg/ml) and 12 h (177.1 pg/ml) before the expiration of these patients, respectively. IL-10 levels of 28.6, 27. 5 and 13.5 pg/ml were detected in sera of three of the remaining four non-survivors that were collected at 2.5 h, 36 h and 30 h before the expiration of these patients, respectively. There was one non-surviving patient who suffered an 80% burn (patient D4 in Table 1 and Fig. 4) and his IL-10 level at 20 days postburn was 13.4 pg/ml. The serum sample of this patient was collected 22 days before death and he was not suffering from sepsis at this stage. In conclusion, an initial increase in serum levels of IL-10 was detected postburn. A marked increase in serum levels of IL-10 was detected in four of the eight septic patients just before their death. It was considered that a lack and/or a delay in the increase of circulating IL-10 may play a significant role in the pathophysiology of sepsis in burned patients.

Cardiac troponin I: a marker for post-burn cardiac injury

Cardiac troponin I (cTnI) was measured by chemiluminescent immunoassay following burn injury. Thirty patients [total body surface area (TBSA) of burn 15-98%] were included in this study and each had four to six blood samples collected at 2-day intervals between the 5th and 14th days post-burn. All patients were found to have increased cTnI on two or more occasions. The mean cTnI concentration was significantly higher in patients with TBSA of burn > 30% (0.34 microg/L compared with 0.09 microg/L, P<0.001) and in those with obvious burn wound exudation (0.32 microg/L compared with 0.12 microg/L, P<0.01). cTnI concentrations peaked at the time when there was obvious burn wound exudation or spontaneous separation of eschar, then decreased after surgical excision. Two patients with persistently high cTnI concentrations developed tachycardia. We conclude that burned patients have varying degrees of non-ischaemic cardiac injury, manifesting as leakage of cTnI from myocytes into the circulation.

Changes in circulating levels of interleukin 6 in burned patients

Interleukin 6 (IL-6) levels in serial serum samples of 10 burned patients were analyzed. The total body surface areas (TBSA) of the burn injury varied from 30 to 85%. Among these 10 patients, five recovered and the other five, who were septic, expired. A significant difference in serum IL-6 values on admission (5-13 h postburn) was found (p < 0.05) between patients who survived or died from burn injury as analyzed by the Wilcoxon's rank sum test. In addition, a significant difference in serum IL-6 on admission was also found (p < 0.05) between patients with TBSA of greater or less than 50%. Afterwards, an initial peak serum IL-6 response was detected within 4 days postburn. Significant differences in the peak serum IL-6 levels were not found between patients with TBSA of greater or less than 50% and patients who survived or expired from burn injury. In the survivors, serum IL-6 remained low, while IL-6 increased markedly starting at about one to two weeks postburn in four of the five nonsurvivors with proven sepsis. Except for the patient who expired 42 days postburn, the maximum serum IL-6 values of the other four nonsurvivors were all greater than those of the five survivors from burn injury. Significant correlation (p < 0.05) relating the change in serum IL-6 and body temperature was observed in only two (one survivor and one nonsurvivor) of the ten patients. Changes in serum IL-6 were also compared with changes in circulating TNF-alpha and IL-8 determined previously. A similar pattern in the dynamic changes of circulating TNF-alpha, IL-8 and IL-6 was observed in the individual burned patient. An increase in serum levels of all three cytokines was detected postburn. Serum levels of three cytokines were significantly higher in the septic patients, who all died. It was considered that all three cytokines analyzed may play a significant role in the pathophysiology of sepsis in burned patients.