IL-10 polymorphism associated with decreased risk for mortality after burn injury

Early expression of IL-10, IL-12, ARG1, and NOS2 genes in peripheral blood mononuclear cells synergistically correlate with patient outcome after burn injury

BACKGROUND

No methods exist to rapidly and accurately quantify the immune insult created by burn injuries. The development of a rapid, noninvasive clinical biomarker assay that evaluates a burn patient's underlying immune dysfunction and predicts clinical outcomes could transform burn care. We aimed to determine a set of peripheral biomarkers that correlates with clinical outcomes of burn patients.

METHODS

This prospective observational study enrolled two patient cohorts within a single burn center into an institutionally approved institutional review board study. Blood draws were performed <48 hours after injury. Initial unbiased immune gene expression analysis compared 23 burn patients and 6 healthy controls using multiplex immune gene expression analysis of RNA from peripheral blood mononuclear cells. We then performed confirmatory outcomes analysis in 109 burn patients and 19 healthy controls using a targeted rapid quantitative polymerase chain reaction. Findings were validated and modeled associations with clinical outcomes using a regression model.

RESULTS

A total of 149 genes with a significant difference in expression from burn patients compared with controls were identified. Pathway analysis identified pathways related to interleukin (IL)-10 and inducible nitric oxide synthase signaling to have significant z scores. quantitative polymerase chain reaction analysis of IL-10, IL-12, arginase 1 (ARG1), and inducible nitric oxide synthase demonstrated that burn injury was associated with increased expression of ARG1 and IL-10, and decreased expression of nitric oxide synthase 2 (NOS2) and IL-12. Burn severity, acute lung injury, development of infection, failure of skin autograft, and mortality significantly correlated with expression of one or more of these genes. Ratios of IL-10/IL-12, ARG1/NOS2, and (ARG1-IL-10)/(NOS2-IL-12) transcript levels further improved the correlation with outcomes. Using a multivariate regression model, adjusting for patient confounders demonstrated that (ARG1-IL-10)/(NOS2-IL-12) significantly correlated with burn severity and development of acute lung injury.

CONCLUSION

We present a means to predict patient outcomes early after burn injury using peripheral blood, allowing early identification of underlying immune dysfunction.

LEVEL OF EVIDENCE

Prognostic/Epidemiological; Level II.

Amnion bilayer for dressing and graft replacement for delayed grafting of full-thickness burns; A study in a rat model

Burn is a common case in developing countries, with over half of fire-related deaths reported in Southeast Asia and full-thickness burns as a high mortality risk. Human amnion has been used as a wound dressing for centuries. In this study, a decellularised amnion overlaid with fibrin, “amnion bilayer (AB),” was used as a dressing immediately after burn and as a graft to replace the scar in Sprague-Dawley rats subjected to full-thickness burn model. The aim was to observe whether amnion bilayer can reduce damages in third-grade burn when skin replacement is deemed impossible. The burn was induced using an electrical solder, heated for 5 mins, and contacted on the rat’s bare skin for 20 s. AB was applied as a (i) dressing immediately after induction and graft after eschar removal. Two groups (n = 6) were compared: AB and Sofra-Tulle ^®, the National Hospital of Indonesia (NHI) protocol. Sections were stained with hematoxylin and eosin and Masson trichrome stains. Immunohistochemistry labelling was used to indicate scars (α-smooth muscle actin [α-SMA] and collagen-1) and angiogenesis (von Willebrand factor). Also, the macrophages inflammatory protein-3α (MIP-3α) indicates an early inflammatory process. The post dressing of the AB group demonstrated hair follicle remains and adipose tissue development. The NHI group appeared with a denatured matrix. Complete healing was seen in the AB group after 28 days with skin appendages similar to normal, while the NHI group showed no appendages in the centre of the actively inflamed area. The α-SMA was found in both groups. Collagen-1 was highly expressed in the NHI group, which led to a scar. Angiogenesis was found more in the AB group. The AB group had shown the capacity to accelerate complete healing and recover skin appendages better than the current protocol.

Association of TLR4 gene polymorphisms with sepsis after a burn injury: findings of the functional role of rs2737190 SNP

Sepsis is a life-threatening organ dysfunction condition caused by a dysregulated response to an infection that is common among patients with moderate to severe burn injury. Previously, genomic variants in Toll-like receptor 4 (TLR4), a key innate immunity receptor, have been associated with sepsis and infection susceptibility. In this study, the association of six TLR4 SNPs with sepsis after burn injury was tested in the Mexican mestizo population. We found that the rs2737190 polymorphism is associated with sepsis after burn trauma. Interestingly, the G allele and GG genotype were associated with a lower risk of developing sepsis. Since the rs2737190 SNP is in the promoter region of the TLR4 gene, we analyzed the possibility that this polymorphism regulates the TLR4 pathway. We cultured peripheral blood mononuclear cells from different genotype carriers and found, after stimulation with LPS, that carriers of the GG genotype showed a higher expression of TLR4, IL6, and TNFα than AA genotype carriers. The results suggest that the GG genotype produces an increase in the TLR4 expression, and therefore an improvement in the immune response. We conclude that the rs2737190 polymorphism may become a useful marker for genetic studies of sepsis in patients after a burn injury.

Prevalence and prognostic impact of inhalation injury among burn patients: A systematic review and meta-analysis

BACKGROUND

The objective of our study was to perform a systematic review and meta-analysis aimed at assessing the prevalence of inhalation injury in burn patients and its prognostic value in relation to in-hospital mortality.

METHODS

We searched the PubMed and EMBASE databases for noninterventional studies published between 1990 and 2018 investigating in-hospital mortality predictors among burn patients.The primary meta-analysis evaluated the association between inhalation injury and mortality. A secondary meta-analysis determined the global estimate of the prevalence of inhalation injury and the rate of mortality. Random effects models were used, and univariate meta-regressions were used to assess sources of heterogeneity. This study is registered in the PROSPERO database with code CRD42019127356.

FINDINGS

Fifty-four studies including a total of 408,157 patients were selected for the analysis. A pooled inhalation prevalence of 15.7% (95% confidence interval, 13.4%-18.3%) was calculated.The summarized odds ratio of in-hospital mortality secondary to an inhalation injury was 3.2 (95% confidence interval, 2.5-4.3). A significantly higher odd of mortality was found among the studies that included all hospitalized burn patients, those that included a lower proportion of male patients, those with a lower mean total body surface area, and those with a lower prevalence of inhalation injury.

CONCLUSION

Despite our study's limitations due to the high risk of bias and the interstudy heterogeneity of some of our analyses, our results revealed a wide range of prevalence rates of inhalation injury and a significant association between this entity and in-hospital mortality in burn patients. However, this association is not significant if adjusted for disease severity.

LEVEL OF EVIDENCE

Systematic review/meta-analysis, level III.

Single Nucleotide Polymorphisms and Post-operative Complications Following Major Gastrointestinal Surgery: a Systematic Review and Meta-analysis

BACKGROUND

The human genome is an under-researched area of pre-operative risk stratification. Studies of genetic polymorphisms and their associations with acute post-operative complications in gastrointestinal surgery have reported statistically significant results, but have varied in methodology, genetic variations studied, and conclusions reached. To provide clarity, we conducted a systematic review and meta-analysis of single nucleotide polymorphisms and their association with post-operative complications after major gastrointestinal surgery.

METHODS

We performed a literature search using Ovid MEDLINE and Web of Science databases. Studies were included if they investigated genetic polymorphisms and their associations with post-operative complications after major gastrointestinal surgery. We extracted clinical and genetic data from each paper and assessed for quality against the STrengthening the REporting of Genetic Association Studies (STREGA) guidelines. Odds ratios were presented, with 95% confidence intervals, to assess strengths of association. We conducted a meta-analysis on TNF-α-308, which had been assessed in three papers.

RESULTS

Our search returned 68 papers, of which 5 were included after screening and full-text review. Twenty-two different single nucleotide polymorphisms (SNPs) were investigated in these studies. We found that all papers were genetic association studies, and had selected SNPs related to inflammation. The outcome investigated was most commonly post-operative infection, but also anastomotic leak and other non-infectious complications. Statistically significant associations were found for TNF-α-308, IL-10-819, PTGS2-765 and IFN-γ-874. There was significant variability in study quality and methodology. We conducted a meta-analysis on associations between the TNF-α-308 polymorphism and post-operative infection and report an OR of 1.18 (CI 0.27-5.21).

CONCLUSIONS

We found biologically plausible associations between SNPs involved in inflammation and post-operative infection, but the available data were too limited and of insufficient quality to reach definitive conclusions. Further work is needed, including genome-wide association studies (GWAS).

Interleukin-6 and interleukin-10 plasma levels and mRNA expression in polytrauma patients

PURPOSE

Host response to polytrauma occasionally has unpredictable outcomes. Immune response is a major factor influencing patient's outcome. This study evaluated the interaction of two main cytokines in immune response after major trauma, specifically interleukin-6 (IL-6) and interleukin-10 (IL-10). Plasma level of these cytokines is determined by mRNA expression of these cytokines genes which may decide the outcome of polytrauma patients.

METHODS

This prospective multicenter trial held at four trauma centers enrolled 54 polytrauma patients [Injury Severity Score (ISS) ≥ 16]. Plasma levels and mRNA expression of IL-6 and IL-10 were measured for 5 days after trauma. Clinical evaluation was conducted to observe whether patients endured multiple organ dysfunction syndrome (MODS) and death. MODS evaluation was performed using sequential organ failure assessment (SOFA). Trauma load which in this study is represented with ISS, plasma level, expression of cytokine genes and patient's outcome were examined with correlation test and statistical analysis.

RESULTS

The elevated IL-6/IL-10 ratio indicated increased activity of systemic inflammation response, especially pro-inflammation response which bears higher probability of progressing to MODS and death. The decline of IL-6/IL-10 ratio with heavy trauma load (ISS > 30) showed that compensatory anti-inflammation response syndrome (CARS) state was more dominant than systemic inflammatory response syndrome (SIRS), indicating that malfunction and failure of immune system eventually lead to MODS and deaths. The statistical significance in plasma level of cytokines was found in the outcome group which was defined as bearing a low trauma load but mortality.

CONCLUSION

The pattern of cytokine levels in inflammation response has great impact on the outcome of polytrauma patients. Further study at the genetic level is needed to investigate inflammation process which may influence patient's outcome.

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.

Association between interleukin-10 polymorphisms and sepsis: a meta-analysis

Genetic association studies of the cytokine interleukin-10 (IL-10) and sepsis have provided inconsistent results. This work attempts to further quantitatively assess the association of three widely evaluated polymorphisms of IL-10 (−592C/A, −819C/T, −1082A/G) with sepsis susceptibility through a meta-analysis. A search of Pubmed, Web of Science and EMBASE databases was performed. Overall, the three polymorphisms have no strong association with sepsis risk. Subgroup analysis by ethnicity showed there was association between sepsis susceptibility with −592C/A in Caucasians (A vs. C: OR 0·78, 95% CI 0·62–1·00, P = 0·05; AA + CA vs. CC: OR 0·75, 95% CI 0·56–1·00, P = 0·05), and with −1082A/G in Asians (G vs. A: OR 1·41, 95% CI 1·04–1·91, P = 0·03; GG + AG vs. AA: OR 2·11, 95% CI 1·07–4·16, P = 0·03). This meta-analysis suggests that −592C/A and −1082A/G polymorphisms are associated with sepsis susceptibility in Caucasian, and Asian populations, respectively.

Inhalation injury severity and systemic immune perturbations in burned adults

OBJECTIVE

We aimed to determine whether the severity of inhalation injury evokes an immune response measurable at the systemic level and to further characterize the balance of systemic pro- and anti-inflammation early after burn and inhalation injury.

BACKGROUND

Previously, we reported that the pulmonary inflammatory response is enhanced with worse grades of inhalation injury and that those who die of injuries have a blunted pulmonary immune profile compared with survivors.

METHODS

From August 2007 to June 2011, bronchoscopy was performed on 80 patients admitted to the burn intensive care unit when smoke inhalation was suspected. Of these, inhalation injury was graded into 1 of 5 categories (0, 1, 2, 3, and 4), with grade 0 being the absence of visible injury and grade 4 corresponding to massive injury. Plasma was collected at the time of bronchoscopy and analyzed for 28 immunomodulating proteins via multiplex bead array or enzyme-linked immunosorbent assay.

RESULTS

The concentrations of several plasma immune mediators were increased with worse inhalation injury severity, even after adjusting for age and % total body surface area (TBSA) burn. These included interleukin (IL)-1RA (P = 0.002), IL-6 (P = 0.002), IL-8 (P = 0.026), granulocyte colony-stimulating factor (P = 0.002), and monocyte chemotactic protein 1 (P = 0.007). Differences in plasma immune mediator concentrations in surviving and deceased patients were also identified. Briefly, plasma concentrations of IL-1RA, IL-6, IL-8, IL-15, eotaxin, and monocyte chemotactic protein 1 were higher in deceased patients than in survivors (P < 0.05 for all), whereas IL-4 and IL-7 were lower (P < 0.05). After adjusting for the effects of age, % TBSA burn, and inhalation injury grade, plasma IL-1RA remained significantly associated with mortality (odds ratio, 3.12; 95% confidence interval, 1.03-9.44). Plasma IL-1RA also correlated with % TBSA burn, inhalation injury grade, fluid resuscitation, Baux score, revised Baux score, Denver score, and the Sequential Organ Failure Assessment score.

CONCLUSIONS

The severity of smoke inhalation injury has systemically reaching effects, which argue in favor of treating inhalation injury in a graded manner. In addition, several plasma immune mediators measured early after injury were associated with mortality. Of these, IL-1RA seemed to have the strongest correlation with injury severity and outcomes measures, which may explain the blunted pulmonary immune response we previously found in nonsurvivors.

A TREM-1 Polymorphism A/T within the Exon 2 Is Associated with Pneumonia in Burn-Injured Patients

Background. The triggering receptor expressed in myeloid cells (TREM-1) is a key mediator in the activation of the local inflammatory response during lung infections. We aimed to evaluate the effect of a functionally relevant TREM-1 single nucleotide polymorphism within the exon 2 (A→T) on the development of pneumonia in burn patients. Objective. To determine whether a single nucleotide polymorphism (SNP) within the exon 2 (A→T) in the TREM-1 gene is associated with ventilator-associated pneumonia (VAP) in burn-injured patients. Methods. 540 patients with ≥10% total body surface area (TBSA) burn injuries or inhalation injury were prospectively enrolled. The influence of a polymorphism (A→T) in exon 2 of the TREM-1 gene was evaluated for association with increased risk of pneumonia by logistic regression analysis. Measurements and Main Results. 209 patients met criteria for VAP. Multivariate regression analysis showed that, after adjustment for potential confounders, we found that carriage of the TREM-1 T allele is associated with more than a 3-fold increased risk of VAP (OR 6.3, 95% CI 4–9). Conclusions. A TREM-1 single nucleotide polymorphism within the exon 2 (A→T) is associated with the development of pneumonia in burn patients.

Early pulmonary immune hyporesponsiveness is associated with mortality after burn and smoke inhalation injury

This prospective study aims to address mortality in the context of the early pulmonary immune response to burn and inhalation injury. The authors collected bronchoalveolar lavage fluid from 60 burn patients within 14 hours of their injury when smoke inhalation was suspected. Clinical and laboratory parameters and immune mediator profiles were compared with patient outcomes. Patients who succumbed to their injuries were older (P = .005), had a larger % TBSA burn (P < .001), and required greater 24-hour resuscitative fluids (P = .002). Nonsurvivors had lower bronchoalveolar lavage fluid concentrations of numerous immunomodulators, including C5a, interleukin (IL)-1β, IL-1RA, IL-8, IL-10, and IL-13 (P < .05 for all). Comparing only those with the highest Baux scores to account for the effects of age and % TBSA burn on mortality, nonsurvivors also had reduced levels of IL-2, IL-4, granulocyte colony-stimulating factor, interferon-γ, macrophage inflammatory protein-1β, and tumor necrosis factor-α (P < .05 for all). The apparent pulmonary immune hyporesponsiveness in those who died was confirmed by in vitro culture, which revealed that pulmonary leukocytes from nonsurvivors had a blunted production of numerous immune mediators. This study demonstrates that the early pulmonary immune response to burn and smoke inhalation may be attenuated in patients who succumb to their injuries.

The year in burns 2010

For 2010, roughly 1446 original burn research articles were published in scientific journals using the English language. This article reviews those with the most impact on burn treatment according to the Editor of one of the major journals (Burns) and his colleagues. As in previous reviews, articles were divided into the following topic areas: epidemiology, demographics of injury, wound characterisation and treatment, critical care, inhalation injury, infection, metabolism and nutrition, psychological considerations, pain and itching management, rehabilitation and long-term outcomes, and burn reconstruction. Each paper is considered very briefly, and the reader is referred to full manuscripts for details.

Pathway genetic load allows simultaneous evaluation of multiple genetic associations

OBJECTIVE

Despite the general success of genome-wide association studies, much heritability remains unidentified in many disease states. Some of this 'missing' heritability may lie in epistatic interactions among multiple loci, which are typically ignored. We utilized a method for simultaneous evaluation of epistatic interactions between allelic variations within genes confined to a single pathway, which we have termed as pathway genetic load (PGL).

METHODS

In separate analyses, we evaluated the risk for sepsis and for death associated with alleles at six loci in the TLR4 signaling and response pathway previously known or suspected to be linked to the development of sepsis after traumatic injury. We evaluated 155 patients with > or =15% TBSA burns and without significant non-burn trauma [ISS < or =16], traumatic or anoxic brain injury or spinal cord injury, who survived > 48 h post-admission. Clinical data were collected prospectively and candidate genotypes were determined by TaqMan assay.

RESULTS

After adjustment for burn size, inhalation injury, age, gender and race, PGL was associated with increased probability for complicated sepsis (aOR=1.59; 95%CI=1.11-2.29; p=0.011) and death (aOR=1.75; 95%CI=1.11-2.76; p=0.017).

CONCLUSION

Relative size and variability of aORs indicate greater power to detect genetic associations with PGL compared to the analysis of loci individually by multivariate logistic regression.