Increased proliferation of hepatic periportal ductal progenitor cells contributes to persistent hypermetabolism after trauma

Prolonged and persistent hypermetabolism and excessive inflammatory response after severe trauma is detrimental and associated with poor outcome. The predisposing pathology or signals mediating this complex response are essentially unknown. As the liver is the central organ mediating the systemic metabolic responses and considering that adult hepatic stem cells are on top of the hierarchy of cell differentiation and may pass epigenetic information to their progeny, we asked whether liver progenitor cells are activated, signal hypermetabolism upon post-traumatic cellular stress responses, and pass this to differentiated progeny. We generated Sox9CreERT2 : ROSA26 EYFP mice to lineage-trace the periportal ductal progenitor cells (PDPCs) and verify the fate of these cells post-burn. We observed increased proliferation of PDPCs and their progeny peaking around two weeks post-burn, concomitant with the hepatomegaly and the cellular stress responses. We then sorted out PDPCs, PDPC-derived hepatocytes and mature hepatocytes, compared their transcriptome and showed that PDPCs and their progeny present a significant up-regulation in signalling pathways associated with inflammation and metabolic activation, contributing to persistent hypermetabolic and hyper-inflammatory state. Furthermore, concomitant down-regulation of LXR signalling in PDPCs and their progeny implicates the therapeutic potential of early and short-term administration of LXR agonists in ameliorating such persistent hypermetabolism.

Alternatively Activated Macrophages Drive Browning of White Adipose Tissue in Burns

OBJECTIVE

The aim of this study was to uncover the mediators and mechanistic events that facilitate the browning of white adipose tissue (WAT) in response to burns.

BACKGROUND

In hypermetabolic patients (eg, burns, cancer), the browning of WAT has presented substantial clinical challenges related to cachexia, atherosclerosis, and poor clinical outcomes. Browning of the adipose tissue has recently been found to induce and sustain hypermetabolism. Although browning appears central in trauma-, burn-, or cancer-induced hypermetabolic catabolism, the mediators are essentially unknown.

METHODS

WAT and blood samples were collected from patients admitted to the Ross Tilley Burn Centre at Sunnybrook Hospital. Wild type, CCR2 KO, and interleukin (IL)-6 KO male mice were purchased from Jax laboratories and subjected to a 30% total body surface area burn injury. WAT and serum collected were analyzed for browning markers, macrophages, and metabolic state via histology, gene expression, and mitochondrial respiration.

RESULTS

In the present study, we show that burn-induced browning is associated with an increased macrophage infiltration, with a greater type 2 macrophage profile in the fat of burn patients. Similar to our clinical findings in burn patients, both an increase in macrophage recruitment and a type 2 macrophage profile were also observed in post burn mice. Genetic loss of the chemokine CCR2 responsible for macrophage migration to the adipose impairs burn-induced browning. Mechanistically, we show that macrophages recruited to burn-stressed subcutaneous WAT (sWAT) undergo alternative activation to induce tyrosine hydroxylase expression and catecholamine production mediated by IL-6, factors required for browning of sWAT.

CONCLUSION

Together, our findings uncover macrophages as the key instigators and missing link in trauma-induced browning.

Anabolic and anticatabolic agents used in burn care: What is known and what is yet to be learned

Major thermal injury induces profound metabolic derangements secondary to an inflammatory "stress-induced" hormonal environment. Several pharmacological interventions have been tested in an effort to halt the hypermetabolic response to severe burns. Insulin, insulin growth factor 1, insulin growth factor binding protein 3, metformin, human growth hormone, thyroid hormones, testosterone, oxandrolone, and propranolol, among others, have been proposed to have anabolic or anticatabolic effects. The aim of this broad analysis of pharmacological interventions was to raise awareness of treatment options and to help establishing directions for future clinical research efforts. A PubMed search was conducted on the anabolic and anticatabolic agents used in burn care. One hundred and thirty-five human studies published between 1999 and 2017 were included in this review. The pharmacological properties, rationale for the treatments, efficacy considerations and side effect profiles are summarized in the article. Many of the drugs tested for investigational purposes in the severely thermally injured are not yet gold-standard therapies in spite of their potential benefit. Propranolol and oxandrolone have shown great promise but further evidence is still needed to clarify their potential use for anabolic and anticatabolic purposes.

Genome-wide comparisons of gene expression in adult versus elderly burn patients

Purpose

Mortality and morbidity rates of elderly burn patients remain high despite numerous advancements in modern burn care. While prior studies have offered first insights on the biochemical changes in elderly burn patients compared to adults, the underlying cellular responses remain largely unknown. In this study, we aim to characterize the transcriptome of elderly burn patients and compare it to adult burn patients to obtain insights into the underlying molecular responses post-burn and to elucidate the effect of advanced age on the acute burn response.

Materials and methods

Microarray data obtained from the Glue Grant Trauma-Related Database was obtained from blood specimens for ten elderly patients (n = 10), each with a set of two sex and total body surface area (TBSA) matched adult controls (n = 20), during the acute phase post-burn. Adult and elderly demographics and clinical outcomes were contrasted using using the Chi-Square test, Fisher’s Exact Test, or two-sample t-tests, as appropriate (p<0.05). Enrichment and heat maps were generated to compare gene expression in elderly versus adult burn patients.

Results

Supervised analysis identified multiple genes that were differentially expressed between the elderly and adult groups. Pathway analysis and heatmap generation suggest that elderly patients share a distinct hypo-inflammatory response in the acute post-burn phase with downregulation of a number of immune-related pathways, including those related to antigen processing, specifically via MHC class I, ubiquitination and proteasome degradation (p<0.001, FDR < .001). Cell signalling pathways, such as NF-κB, C-type lectin receptor, and T cell receptor signalling were also significantly downregulated in elderly burn patients, as well as those relating to antiviral immunity (p<0.001, FDR < .001). Many genes which were observed to be upregulated in elderly patients with high TBSA burn injuries were associated with destruction-related cellular pathways such as complement activation and immunoglobulin production (p<0.005, FDR <0.01).

Conclusions

The altered inflammatory and immune responses at the transcriptome level in elderly patients after burn are indicative of a failure in elderly burn patients to initiate an appropriate inflammatory and stress response during the acute phase post-burn.

Allogeneic mesenchymal stem cells for treatment of severe burn injury

The most important determinant of survival post-burn injury is wound healing. For decades, allogeneic mesenchymal stem cells (MSCs) have been suggested as a potential treatment for severe burn injuries. This report describes a patient with a severe burn injury whose wounds did not heal with over 18 months of conventional burn care. When treated with allogeneic MSCs, wound healing accelerated with no adverse treatment complications. Wound sites showed no evidence of keloids or hypertrophic formation during a 6-year follow-up period. This therapeutic use of allogeneic MSCs for large non-healing burn wounds was deemed safe and effective and has great treatment potential.

Browning of white adipose tissue after a burn injury promotes hepatic steatosis and dysfunction

Burn patients experiencing hypermetabolism develop hepatic steatosis, which is associated with liver failure and poor outcomes after the injury. These same patients also undergo white adipose tissue (WAT) browning, which has been implicated in mediating post-burn cachexia and sustained hypermetabolism. Despite the clinical presentation of hepatic steatosis and WAT browning in burns, whether or not these two pathological responses are linked remains poorly understood. Here, we show that the burn-induced WAT browning and its associated increased lipolysis leads to the accelerated development of hepatic steatosis in mice. Deletion of interleukin 6 (IL-6) and the uncoupling protein 1 (UCP1), regulators of burn-induced WAT browning completely protected mice from hepatic steatosis after the injury. Treatment of post-burn mice with propranolol or IL-6 receptor blocker attenuated burn-induced WAT browning and its associated hepatic steatosis pathology. Lipidomic profiling in the plasma of post-burn mice and burn patients revealed elevated levels of damage-inducing lipids (palmitic and stearic acids), which induced hepatic endoplasmic reticulum (ER) stress and compromised hepatic fat oxidation. Mechanistically, we show that hepatic ER stress after a burn injury leads to a greater ER-mitochondria interaction, hepatocyte apoptosis, oxidative stress, and impaired fat oxidation. Collectively, our findings uncover an adverse "cross-talk" between the adipose and liver tissue in the context of burn injury, which is critically mediated by WAT browning.

Promotion of dermal regeneration using pullulan/gelatin porous skin substitute

Tissue-engineered dermal substitutes represent a promising approach to improve wound healing and provide more sufficient regeneration, compared with current clinical standards on care of large wounds, early excision, and grafting of autografts. However, inadequate regenerative capacity, impaired regeneration/degradation profile, and high cost of current commercial tissue-engineered dermal regeneration templates hinder their utilization, and the development of an efficient and cost-effective tissue-engineered dermal substitute remains a challenge. Inspired from our previously reported data on a pullulan/gelatin scaffold, here we present a new generation of a porous pullulan/gelatin scaffold (PG2) served as a dermal substitute with enhanced chemical and structural characteristics. PG2 shows excellent biocompatibility (viability, migration, and proliferation), assessed by in vitro incorporation of human dermal fibroblasts in comparison with the Integra® dermal regeneration template (Control). When applied on a mouse full-thickness excisional wound, PG2 shows rapid scaffold degradation, more granulation tissue, more collagen deposition, and more cellularity in comparison with Control at 20 days post surgery. The faster degradation is likely due to the enhanced recruitment of inflammatory macrophages to the scaffold from the wound bed, and that leads to earlier maturation of granulation tissue with less myofibroblastic cells. Collectively, our data reveal PG2's characteristics as an applicable dermal substitute with excellent dermal regeneration, which may attenuate scar formation.

NLRP3 inflammasome mediates white adipose tissue browning after burn

A hallmark after burn is the stress and inflammatory-induced hypermetabolic response. Recently, we and others found that browning of white adipose tissue (WAT) is a critical component of this complex detrimental response. Although browning and inflammation have been independently delineated to occur after injury, their interaction is currently not well defined. One of the master regulators of inflammation and adipose tissue remodeling after burns is nucleotide-binding and oligomerization domain, leucine rich repeat and pyrin domain containing 3 (NLRP3) inflammasome. The aim of this this study was to determine whether NLRP3 modulates and activates WAT browning after burn. To obtain molecular and mechanistic insights, we used an NLRP3 knockout (NLRP3^-/-) murine burn model. We demonstrated that genetic deletion of NLRP3 promoted persistent and augmented browning in adipocytes, evidenced by increased gene expression of peroxisome proliferator-activated receptor γ and CIDEA at 3 days (5.74 vs. 0.29, P < 0.05; 26.0 vs. 0.71, P < 0.05) and uncoupling protein 1 (UCP1) and PGC1α at 7 days (7,406 vs. 3,894, P < 0.05; 20.6 vs. 2.52, P < 0.01) and enhanced UCP1 staining and multilocularity. Additionally, the main regulator of postburn WAT browning, IL-6, was elevated in the plasma acutely after burn in NLRP3^-/- compared with wild-type counterparts (478.9 vs. 67.1 pg/mL, P < 0.05 at 3 days). These results suggest that NLRP3 has antibrowning effects and that blocking NLRP3 increases thermogenesis and augments browning via increased levels of IL-6. Our findings provide insights into targeting innate inflammatory systems for regulation of adaptive thermogenesis, a critical response after burns and other hypermetabolic conditions.

Aggregated and Hyperstable Damage-Associated Molecular Patterns Are Released During ER Stress to Modulate Immune Function

Chronic ER stress occurs when protein misfolding in the Endoplasmic reticulum (ER) lumen remains unresolved despite activation of the unfolded protein response. We have shown that traumatic injury such as a severe burn leads to chronic ER stress in vivo leading to systemic inflammation which can last for more than a year. The mechanisms linking chronic ER stress to systemic inflammatory responses are not clear. Here we show that induction of chronic ER stress leads to the release of known and novel damage-associated molecular patterns (DAMPs). The secreted DAMPs are aggregated and markedly protease resistant. ER stress-derived DAMPs activate dendritic cells (DCs) which are then capable of polarizing naïve T cells. Our findings indicate that induction of chronic ER stress may lead to the release of hyperstable DAMPs into the circulation resulting in persistent systemic inflammation and adverse outcomes.

Metformin prevents the pathological browning of subcutaneous white adipose tissue

Objective

Browning, the conversion of white adipose tissue (WAT) to a beige phenotype, has gained interest as a strategy to induce weight loss and improve insulin resistance in metabolic disorders. However, for hypermetabolic conditions stemming from burn trauma or cancer cachexia, browning is thought to contribute to energy wasting and supraphysiological nutritional requirements. Metformin's impact on this phenomenon and underlying mechanisms have not been explored.

Methods

We used both a murine burn model and human ex vivo adipose explants to assess metformin and 5-aminoimidazole-4-carboxamide ribonucleotide (AICAR)'s effects on the development of subcutaneous beige adipose. Enzymes involved in fat homeostasis and browning, as well as mitochondrial dynamics, were assessed to determine metformin's effects.

Results

Treatment with the biguanide metformin lowers lipolysis in beige fat by inducing protein phosphatase 2A (PP2A) independently of adenosine monophosphate kinase (AMPK) activation. Increased PP2A activity catalyzes the dephosphorylation of acetyl-CoA carboxylase (Ser 79) and hormone sensitive lipase (Ser 660), thus promoting fat storage and the “whitening” of otherwise lipolytic beige adipocytes. Moreover, co-incubation of metformin with the PP2A inhibitor okadaic acid countered the anti-lipolytic effects of this biguanide in human adipose. Additionally, we show that metformin does not activate this pathway in the WAT of control mice and that AICAR sustains the browning of white adipose, offering further evidence that metformin acts independently of this cellular energy sensor.

Conclusions

This work provides novel insights into the mechanistic underpinnings of metformin's therapeutic benefits and potential as an agent to reduce the lipotoxicity associated with hypermetabolism and adipose browning.

•

Metformin prevents the catabolism of murine iWAT tissue post-burn injury.

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Mitochondrial respiration and uncoupling in adipose are decreased by metformin.

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Metformin, independently of AMPK, reduces adipose lipolysis and β-oxidation via PP2A.

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AICAR treatment activates AMPK in peripheral adipose leading to sustained browning.

•

PP2A is directly induced by metformin in scWAT, lowering ACC/HSL phosphorylation.

Management and prevention of drug resistant infections in burn patients

Introduction: Despite modern advances, the primary cause of death after burns remains infection and sepsis. A key factor in determining outcomes is colonization with multi-drug resistant (MDR) organisms. Infections secondary to MDR organisms are challenging due to lack of adequate antibiotic treatment, subsequently prolonging hospital stay and increasing risk of adverse outcomes. Areas covered: This review highlights the most frequent organisms colonizing burn wounds as well as the most common MDR bacterial infections. Additionally, we discuss different treatment modalities and MDR infection prevention strategies as their appropriate management would minimize morbidity and mortality in this population. We conducted a search for articles on PubMed, Web of Science, Embase, Cochrane, Scopus and UpToDate with applied search strategies including a combination of: "burns, 'thermal injury,' 'infections,' 'sepsis,' 'drug resistance,' and 'antimicrobials.' Expert opinion: Management and prevention of MDR infections in burns is an ongoing challenge. We highlight the importance of preventative over therapeutic strategies, which are easy to implement and cost-effective. Additionally, targeted, limited use of antimicrobials can be beneficial in burn patients. A promising future area of investigation within this field is post-trauma microbiome profiling. Currently, the best treatment strategy for MDR in burn patients is prevention.

Acute and long-term clinical, neuropsychological and return-to-work sequelae following electrical injury: a retrospective cohort study

OBJECTIVE

To determine acute and long-term clinical, neuropsychological, and return-to-work (RTW) effects of electrical injuries (EIs). This study aims to further contrast sequelae between low-voltage and high-voltage injuries (LVIs and HVIs). We hypothesise that all EIs will result in substantial adverse effects during both phases of management, with HVIs contributing to greater rates of sequelae.

DESIGN

Retrospective cohort study evaluating EI admissions between 1998 and 2015.

SETTING

Provincial burn centre and rehabilitation hospital specialising in EI management.

PARTICIPANTS

All EI admissions were reviewed for acute clinical outcomes (n=207). For long-term outcomes, rehabilitation patients, who were referred from the burn centre (n=63) or other burn units across the province (n=65), were screened for inclusion. Six patients were excluded due to pre-existing psychiatric conditions. This cohort (n=122) was assessed for long-term outcomes. Median time to first and last follow-up were 201 (68-766) and 980 (391-1409) days, respectively.

OUTCOME MEASURES

Acute and long-term clinical, neuropsychological and RTW sequelae.

RESULTS

Acute clinical complications included infections (14%) and amputations (13%). HVIs resulted in greater rates of these complications, including compartment syndrome (16% vs 4%, p=0.007) and rhabdomyolysis (12% vs 0%, p<0.001). Rates of acute neuropsychological sequelae were similar between voltage groups. Long-term outcomes were dominated by insomnia (68%), anxiety (62%), post-traumatic stress disorder (33%) and major depressive disorder (25%). Sleep difficulties (67%) were common following HVIs, while the LVI group most frequently experienced sleep difficulties (70%) and anxiety (70%). Ninety work-related EIs were available for RTW analysis. Sixty-one per cent returned to their preinjury employment and 19% were unable to return to any form of work. RTW rates were similar when compared between voltage groups.

CONCLUSIONS

This is the first investigation to determine acute and long-term patient outcomes post-EI as a continuum. Findings highlight substantial rates of neuropsychological and social sequelae, regardless of voltage. Specialised and individualised early interventions, including screening for mental health concerns, are imperative to improvingoutcomes of EI patients.

Examining the contribution of surrounding intact skin during cutaneous healing

Severe cutaneous wounds expose the body to the external environment, which may lead to impairments in bodily functions and increased risk of infection. There is a need to develop skin substitutes which could effectively promote complete skin regeneration following an injury. Murine models are used to test such skin substitutes, but their healing involves contraction of the dermis not found in human wounds. We have previously described a device called a dome, which comes in two models, that is used to prevent skin contraction in mice. One model provides a physical barrier to minimize contraction, and the other model has additional perforations in the barrier to allow cellular contribution from the surrounding intact skin. Taking advantage of an enhanced version of these two models, we compared granulation tissue formation, the extent of vascularization, and the transition to myofibroblastic phenotype between the models. We enhanced the dome by developing a twist open cap dome and applied the two models of the dome into the excisional wound biopsy in mice. We demonstrate that the dome can be used to prevent skin contraction in mice. The control model prevented skin contraction while barricading the contribution of surrounding intact skin. When not barricaded, the intact skin enhances wound healing by increasing the number of myofibroblasts and neovascularization. Using a novel model of inhibition of skin contraction in rodents, we examined the contribution from the surrounding intact skin to granulation tissue formation, myofibroblastic differentiation, and neovascularization during the course of skin healing in mice.

The effect of diabetes on burn patients: a retrospective cohort study

BACKGROUND

Hyperglycemia during the acute phase after burn is associated with increased morbidity and mortality. There is little knowledge regarding the effect of pre-existing hyperglycemia in the form of diabetes on the outcomes after severe burns. The objective is to determine the impact of diabetes on clinical outcomes after burns.

METHODS

Single-center cohort study where adult diabetic (n = 76) and non-diabetic (n = 1186) burn patients admitted between 2006 and 2016 were included. Diabetic patients were stratified into those with well-controlled diabetes (n = 24) and poorly controlled diabetes (n = 33) using a HbA1c of 7% as a cutoff; additionally, diabetics were divided into well-controlled glycemia (n = 47) and poorly controlled glycemia (n = 22) based on daily blood glucose measurements during hospitalization.

RESULTS

On univariate analysis, diabetics had a significantly increased median length of stay per percent total body surface area burn (2.1 vs. 1.6 days; p = 0.0026) and a greater number of overall morbidity (1.39 ± 1.63 vs. 0.8 ± 1.24; p = 0.001). After adjustment for patient characteristics, diabetics were associated with significantly increased total morbidity (RR 1.5; 95% CI 1.1-1.9). At discharge, almost two thirds of diabetics needed an escalation of anti-diabetic medication and a quarter had newly developed insulin dependency. There were no differences in morbidity or mortality in the diabetic subgroups.

CONCLUSIONS

Diabetics had a longer hospitalization and increased morbidity, regardless of the quality of their anti-diabetic therapy prior to injury. Additionally, diabetes in burn patients is associated with an increased risk of total morbidity.

5-HT1A Receptor Function Makes Wound Healing a Happier Process

Skin wound healing is a multistage phenomenon that is regulated by cell–cell interplay and various factors. Endogenous serotonin is an important neurotransmitter and cytokine. Its interaction with the serotonin 1A receptor (5-HTR1A) delivers downstream cellular effects. The role of serotonin (5-hydroxytryptamine, 5-HT) and the 5-HT1A receptor has been established in the regeneration of tissues such as the liver and spinal motor neurons, prompting the investigation of the role of 5-HT1A receptor in skin healing. This study assessed the role of 5-HT1A receptor in excisional wound healing by employing an excisional punch biopsy model on 5-Ht1a receptor knockout mice. Post-harvest analysis revealed 5-Ht1a receptor knockout mice showed impaired skin healing, accompanied by a greater number of F4/80 macrophages, which prolongs the inflammatory phase of wound healing. To further unravel this phenomenon, we employed the 5-HT1A receptor agonist [(R)-(+)-8-Hydroxy-DPAT hydrobromide] as a topical cream treatment in an excisional punch biopsy model. The 5-HT1A receptor agonist treated group showed a smaller wound area, scar size, and improved neovascularization, which contributed to improve healing outcomes as compared to the control. Collectively, these findings revealed that serotonin and 5-HT1A receptor play an important role during the healing process. These findings may open new lines of investigation for the potential treatment alternatives to improve skin healing with minimal scarring.

Burn injury and multiple sclerosis: A retrospective case-control study

OBJECTIVES

The purpose of this study was to determine whether having a previous diagnosis of multiple sclerosis (MS) changed acute care needs in burn-injured patients.

METHODS

This was a retrospective case-control study that included adult (aged ≥18years) patients with an acute burn injury. Control patients were matched with eleven patients with a history of MS at a 4:1 ratio. Outcomes included fluid resuscitation volumes, temperature, heart rate, mean arterial pressure, in-hospital complications, and hospital length of stay (LOS).

RESULTS

There were fifty-five patients included and of those, eleven had a documented history of MS. Fluid resuscitation volumes, temperature, heart rate, and mean arterial pressure were similar between groups during the resuscitation period (p>0.05). LOS was similar between both groups (12, IQR: 2-17 vs. median 16, IQR: 12-21; p=0.090). However, when normalized to % TBSA burn, patients with MS had a significantly higher median LOS/% TBSA burned (1.2, IQR: 0.7-2.0 vs. 2.1, IQR: 1.1-7.1; p=0.031).

CONCLUSIONS

Patients with concurrent burn injuries and MS have a significantly longer LOS/% TBSA burn suggesting that more time is required to heal their wounds. Surprisingly, there were no other significant differences in the after the burn acute phase between these two cohorts.

Stem cells derived from burned skin - The future of burn care

BACKGROUND

Thermal injuries affect millions of adults and children worldwide and are associated with high morbidity and mortality. The key determinant for the survival of burns is rapid wound healing. Large wounds exceed intrinsic wound-healing capacities, and the currently available coverage materials are insufficient due to lack of cellularity, availability or immunological rejection.

METHODS

Using the surgically debrided tissue, we isolated viable cells from burned skin. The isolated cells cultured in tissue culture dishes and characterized.

FINDINGS

We report here that debrided burned skin, which is routinely excised from patients and otherwise considered medical waste and unconsciously discarded, contains viable, undamaged cells which show characteristics of mesenchymal skin stem cells. Those cells can be extracted, characterized, expanded, and incorporated into created epidermal-dermal substitutes to promote wound healing in immune-compromised mice and Yorkshire pigs without adverse side effects.

INTERPRETATION

These findings are of paramount importance and provide an ideal cell source for autologous skin regeneration. Furthermore, this study highlights that skin contains progenitor cells resistant to thermal stress. FUND: Canadian Institutes of Health Research # 123336. CFI Leader's Opportunity Fund: Project # 25407 National Institutes of Health 2R01GM087285-05A1. EMHSeed: Fund: 500463, A generous donation from Toronto Hydro. Integra© Life Science Company provided the meshed bilayer Integra© for porcine experiments.

NLRP3 Inflammasome Modulates Post-Burn Lipolysis and Hepatic Fat Infiltration via Fatty Acid Synthase

Burns result in generalized catabolism, lipolysis, and hyperinflammation. NLRP3 inflammasome, a mediator of hyperinflammation, is upregulated in burn patients' adipose tissue within 7 days post-burn. However, its role during the acute phase is unknown. Here, wild-type (WT) and NLRP3 knockout (NLRP3^-/-) mice were exposed to 25% TBSA scald burn. Flow cytometric analysis demonstrated greater liver macrophage infiltration in NLRP3^-/- yet decreased protein expression of NLRP3 components, ER stress, and apoptosis. NLRP3^-/- had increased circulating free fatty acids (FFA), fatty deposition and liver weight 1 hour post-burn. Alterations in adipose fatty acid synthase (Fasn) expression affects FFA levels post-burn; WT have an early peak in Fasn gene and protein expression that is lost in NLRP3^-/-, resulting in increased lipolysis and hepatic fatty deposition. In summary, our findings reveal that NLRP3 inflammasome activation is a double-edged sword. While prolonged inflammation and long-term effects of macrophage activation are associated with poor outcomes, acute inflammation may be beneficial. These results highlight the important metabolic role that NLRP3 inflammasome plays in the acute phase, ultimately affecting survival post-burn.

Severe Physical Complications among Survivors of Stevens-Johnson Syndrome and Toxic Epidermal Necrolysis

INTRODUCTION

Few studies have reported the physical complications among Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) survivors.

OBJECTIVE

The aim of this study was to comprehensively characterize the physical complications among SJS/TEN survivors and to learn about patients' perspectives of surviving SJS/TEN.

METHODS

SJS/TEN survivors older than 18 years of age were assessed by different methods: a medical interview; a questionnaire assessing patients' perspectives; thorough skin, oral mucous membrane, and ophthalmic examinations; and a retrospective assessment of medical records.

RESULTS

Our cohort consisted of 17 patients with a mean time of 51.6 ± 74.7 months (median 9, range 1-228) following SJS/TEN. The most common physical complications identified in the medical examination were post-inflammatory skin changes (77%), cutaneous scars (46%), dry eyes (44%), symblepharon, and chronic ocular surface inflammation (33% each). Novel physical sequelae included chronic fatigue (76%) and pruritus (53%). We also found a novel association between the number of mucous membranes affected in the acute phase of SJS/TEN and hair loss during the 6 months following hospital discharge; hair loss was reported in 88% of the group of patients who had three or more mucous membranes affected versus 29% of patients who had less than three mucous membranes involved (p = 0.0406). Following hospital discharge due to SJS/TEN, 59% of patients were followed by a dermatologist, although 88% had dermatological complications; 6% were followed by an ophthalmologist, even though 67% had ophthalmological complications; and 6% of female survivors were followed by a gynecologist, even though 27% had gynecological complications.

CONCLUSION

Survivors of SJS/TEN suffer from severe physical complications impacting their health and lives that are mostly under recognized and not sufficiently treated by medical professionals.

Contributors to the length-of-stay trajectory in burn-injured patients

OBJECTIVES

Burn patients have a highly variable length-of-stay (LOS) due to the complexity of the injury itself. The LOS for burn patients is estimated as one day per percent total body surface area (TBSA) burn. To focus care expectation and prognosis we aimed to identify key factors that contribute to prolonged LOS.

METHODS

This was a retrospective cohort-study (2006-2016) in an adult burn-centre that included patients with ≥10% TBSA burn. Patients were stratified into expected-LOS (<2 days LOS/%TBSA) and longer-than-expected-LOS (≥2 days LOS/%TBSA). We assessed demographics, comorbidities, and in-hospital complications. Logistic regression and propensity matching was utilized.

RESULTS

Of the 583 total patients, 477 had an expected-LOS whereas 106 a longer-than-expected-LOS. Non-modifiable factors such as age, 3rd degree TBSA%, inhalation injuries and comorbidities were greater in the exceeded LOS patients. Subsequent matched analysis revealed factors like number of procedures performed, days ventilated and in-hospital complications (bacteremia, pneumonia, sepsis, graft loss, and respiratory failure) were significantly increased in the longer-than-expected-LOS group.

CONCLUSIONS

Progress has been made to update the conventional one day/%TBSA to better aid health care providers in giving appropriate outcomes for patients and their families and to supply intensive care units with valuable data to assess quality of care and to improve patient prognosis.