ß-Adrenergic blockade attenuates adverse adipose tissue responses after burn.

Severe burn injuries are defined by a prolonged hypermetabolic response characterized by increases in resting energy expenditure, systemic catabolism, and multi-organ dysfunction. The sustained elevation of catecholamines following a burn injury is thought to significantly contribute to this hypermetabolic response, leading to changes in adipose tissue such as increased lipolysis and the browning of subcutaneous white adipose tissue (WAT). Failure to mitigate these adverse changes within the adipose tissue has been shown to exacerbate the post-burn hypermetabolic response and lead to negative outcomes. Propranolol, a non-selective ß-blocker, has been clinically administered to improve outcomes of pediatric and adult burn patients, but there is inadequate knowledge of its effects on the distinct adipose tissue depots. In this study, we investigated the adipose depot-specific alterations that occur in response to burn injury. Moreover, we explored the therapeutic effects of ß-adrenoceptor blockade via the drug propranolol in attenuating these burn-induced pathophysiological changes within the different fat depots. Using a murine model of thermal injury, we show that burn injury induces endoplasmic reticulum (ER) stress in the epididymal (eWAT) but not in the inguinal (iWAT) WAT depot. Conversely, burn injury induces the activation of key lipolytic pathways in both eWAT and iWAT depots. Treatment of burn mice with propranolol effectively mitigated adverse burn-induced alterations in the adipose by alleviating ER stress in the eWAT and reducing lipolysis in both depots. Furthermore, propranolol treatment in post-burn mice attenuated UCP1-mediated subcutaneous WAT browning following injury. Overall, our findings suggest that propranolol serves as an effective therapeutic intervention to mitigate the adverse changes induced by burn injury, including ER stress, lipotoxicity, and WAT browning, in both adipose tissue depots. KEY MESSAGES: Burn injury adversely affects adipose tissue metabolism via distinct changes in both visceral and subcutaneous adipose depots. Propranolol, a non-selective ß-adrenergic blocker, attenuates many of the adverse adipose tissue changes mediated by burn injury.

BURNS INDUCE ALTERATIONS IN THE ACYL PROTEOME OF MICE AND HUMANS.

ABSTRACT: Hypermetabolic reprogramming triggered by thermal injury causes substantial morbidity and mortality. Despite the therapeutic potential of targeting this response, the underlying mechanisms remain poorly understood. Interestingly, protein S-acylation is a reversible posttranslational modification induced by metabolic alterations via DHHC acyltransferases. While this modification aids in the regulation of cellular functions, deregulated S-acylation contributes to various diseases by altering protein structure, stability, and localization. However, whether and how S-acylation may impact morbidity and mortality during postburn hypermetabolism is unknown. In this study, we discovered that alterations in the acyl proteome play a key role in mediating adverse outcomes that occur after burn injury. Using a murine model, we show that burn injury induces profound changes in the expression of various DHHC isoforms in metabolic organs central to regulating postburn hypermetabolism, the adipose tissue, and liver. This was accompanied by increased levels of S-acylated proteins in several pathways involved in mediating the adverse hypermetabolic response, including ER stress, lipolysis, and browning. In fact, similar results were also observed in adipose tissue from severely burned patients, as reflected by increased S-acylation of ERK1/2, eIF2a, ATGL, FGF21, and UCP1 relative to nonburn controls. Importantly, pharmacologically targeting this posttranslational modification using a nonselective DHHC inhibitor effectively attenuated burn-induced ER stress, lipolysis, and browning induction in an ex vivo explant model. Together, these findings suggest that S-acylation may facilitate the protein activation profile that drives burn-induced hypermetabolism and that targeting it could potentially be an effective strategy to restore metabolic function and improve outcomes after injury.

The long-term intercorrelation between post-burn pain, anxiety, and depression: a post hoc analysis of the "RE-ENERGIZE" double-blind, randomized, multicenter placebo-controlled trial.

BACKGROUND: Despite the growing prevalence of burn survivors, a gap persists in our understanding of the correlation between acute burn trauma and the long-term impact on psychosocial health. This study set out to investigate the prevalence of long-term pain and symptoms of anxiety and depression in survivors of extensive burns, comparing this to the general population, and identify injury and demographic-related factors predisposing individuals to psychosocial compromise. METHODS: RE-ENERGIZE was an international, double-blinded, randomized-controlled trial that enrolled 1200 patients with partial- or full-thickness burns that required surgical treatment. For the post hoc analysis, we excluded participants who did not complete the Short Form Health Survey (SF-36) questionnaire. Normative data were taken from the 2021 National Health Interview Survey dataset. Propensity score matching was performed using the nearest-neighbor 1-to-1 method, and the two cohorts were compared in terms of chronic pain, and symptoms of anxiety and depression. A multivariable analysis was performed on the burns cohort to identify factors predicting post-discharge pain and symptoms of anxiety and depression. RESULTS: A total of 600 burn patients and 26,666 general population adults were included in this study. Following propensity score matching, both groups comprised 478 participants each, who were predominately male, white, overweight and between 20 and 60 years old. Compared to the general population, burn patients were significantly more likely to report the presence of moderate and a lot of pain (p = 0.002). Symptoms of anxiety were significantly higher in the burn population in two of four levels (most of the time; some of the time; p < 0.0001 for both). Responders in the burn population were significantly less likely to report the absence of depressive symptoms (p < 0.0001). Burn patients were also significantly more likely to report that their mental health affects their social life. TBSA, history of depression, and female sex were identified as independently associated factors for pain, anxiety, and depressive symptoms. The presence of chronic pain and anxiety symptoms independently predicted for symptoms of depression. CONCLUSIONS: Analyzing the largest multicenter cohort of patients with extensive burns, we find that burn injury is associated with chronic pain, and symptoms of anxiety and depression. In addition, TBSA-burned and history of depression directly correlate with the prevalence of chronic pain, and symptoms of anxiety and depression. Finally, pain, and symptoms of anxiety and depression are interrelated and may have interactive effects on the process of recovery following burn injury. Burn patients would, therefore, benefit from a multidisciplinary team approach with early mobilization of pain and mental health experts, in order to promptly prevent the development of psychosocial challenges and their consequences.

Dermal Regeneration Template in the Management and Reconstruction of Burn Injuries and Complex Wounds: A Review.

Background: Dermal scaffolds have created a paradigm shift for burn and wound management by providing improved healing and less scarring, while improving cosmesis and functionality. Dermal regeneration template (DRT) is a bilayer membrane for dermal regeneration developed by Yannas and Burke in the 1980s. The aim of this review is to summarize clinical evidence for dermal scaffolds focusing on DRT for the management and reconstruction of burn injuries and complex wounds. Methods: A comprehensive search of PubMed was performed from the start of indexing through November 2022. Articles reporting on DRT use in patients with burns, limb salvage, and wound reconstruction were included with focus on high-level clinical evidence. Results: DRT has become an established alternative option for the treatment of full-thickness and deep partial-thickness burns, with improved outcomes in areas where cosmesis and functionality are important. In the management of diabetic foot ulcers, use of DRT is associated with high rates of complete wound healing with a low risk of adverse outcomes. DRT has been successfully used in traumatic and surgical wounds, showing particular benefit in deep wounds and in the reconstruction of numerous anatomical sites. Conclusions: Considerable clinical experience has accrued with the use of DRT beyond its original application for thermal injury. A growing body of evidence from clinical studies reports the successful use of DRT to improve clinical outcomes and quality of life across clinical indications at a number of anatomical sites.

Subcutaneous white adipose tissue independently regulates burn-induced hypermetabolism via immune-adipose crosstalk.

Severe burns induce a chronic hypermetabolic state that persists well past wound closure, indicating that additional internal mechanisms must be involved. Adipose tissue is suggested to be a central regulator in perpetuating hypermetabolism, although this has not been directly tested. Here, we show that thermogenic adipose tissues are activated in parallel to increases in hypermetabolism independent of cold stress. Using an adipose tissue transplantation model, we discover that burn-derived subcutaneous white adipose tissue alone is sufficient to invoke a hypermetabolic response in a healthy recipient mouse. Concomitantly, transplantation of healthy adipose tissue alleviates metabolic dysfunction in a burn recipient. We further show that the nicotinic acetylcholine receptor signaling pathway may mediate an immune-adipose crosstalk to regulate adipose tissue remodeling post-injury. Targeting this pathway could lead to innovative therapeutic interventions to counteract hypermetabolic pathologies.