Glycocalyx Shedding is Enhanced by Age and Correlates with Increased Fluid Requirement in Patients with Major Burns

Pathophysiology of Severe Burn Injuries: New Therapeutic Opportunities From a Systems Perspective

Severe burn injury elicits a profound stress response with the potential for high morbidity and mortality. If polytrauma is present, patient outcomes appear to be worse. Sex-based comparisons indicate females have worse outcomes than males. There are few effective drug therapies to treat burn shock and secondary injury progression. The lack of effective drugs appears to arise from the current treat-as-you-go approach rather than a more integrated systems approach. In this review, we present a brief history of burns research and discuss its pathophysiology from a systems' perspective. The severe burn injury phenotype appears to develop from a rapid and relentless barrage of damage-associated molecular patterns, pathogen-associated molecular patterns, and neural afferent signals, which leads to a state of hyperinflammation, immune dysfunction, coagulopathy, hypermetabolism, and intense pain. We propose that if the central nervous system control of cardiovascular function and endothelial-glycocalyx-mitochondrial coupling can be restored early, these secondary injury processes may be minimized. The therapeutic goal is to switch the injury phenotype to a healing phenotype by reducing fluid leak and maintaining tissue O2 perfusion. Currently, no systems-based therapies exist to treat severe burns. We have been developing a small-volume fluid therapy comprising adenosine, lidocaine, and magnesium (ALM) to treat hemorrhagic shock, traumatic brain injury, and sepsis. Our early studies indicate that the ALM therapy holds some promise in supporting cardiovascular and pulmonary functions following severe burns. Future research will investigate the ability of ALM therapy to treat severe burns with polytrauma and sex disparities, and potential translation to humans.

Advancements in Regenerative Hydrogels in Skin Wound Treatment: A Comprehensive Review

This state-of-the-art review explores the emerging field of regenerative hydrogels and their profound impact on the treatment of skin wounds. Regenerative hydrogels, composed mainly of water-absorbing polymers, have garnered attention in wound healing, particularly for skin wounds. Their unique properties make them well suited for tissue regeneration. Notable benefits include excellent water retention, creating a crucially moist wound environment for optimal healing, and facilitating cell migration, and proliferation. Biocompatibility is a key feature, minimizing adverse reactions and promoting the natural healing process. Acting as a supportive scaffold for cell growth, hydrogels mimic the extracellular matrix, aiding the attachment and proliferation of cells like fibroblasts and keratinocytes. Engineered for controlled drug release, hydrogels enhance wound healing by promoting angiogenesis, reducing inflammation, and preventing infection. The demonstrated acceleration of the wound healing process, particularly beneficial for chronic or impaired healing wounds, adds to their appeal. Easy application and conformity to various wound shapes make hydrogels practical, including in irregular or challenging areas. Scar minimization through tissue regeneration is crucial, especially in cosmetic and functional regions. Hydrogels contribute to pain management by creating a protective barrier, reducing friction, and fostering a soothing environment. Some hydrogels, with inherent antimicrobial properties, aid in infection prevention, which is a crucial aspect of successful wound healing. Their flexibility and ability to conform to wound contours ensure optimal tissue contact, enhancing overall treatment effectiveness. In summary, regenerative hydrogels present a promising approach for improving skin wound healing outcomes across diverse clinical scenarios. This review provides a comprehensive analysis of the benefits, mechanisms, and challenges associated with the use of regenerative hydrogels in the treatment of skin wounds. In this review, the authors likely delve into the application of rational design principles to enhance the efficacy and performance of hydrogels in promoting wound healing. Through an exploration of various methodologies and approaches, this paper is poised to highlight how these principles have been instrumental in refining the design of hydrogels, potentially revolutionizing their therapeutic potential in addressing skin wounds. By synthesizing current knowledge and highlighting potential avenues for future research, this review aims to contribute to the advancement of regenerative medicine and ultimately improve clinical outcomes for patients with skin wounds.

Lung Protection After Severe Thermal Burns With Adenosine, Lidocaine, and Magnesium (ALM) Resuscitation and Importance of Shams in a Rat Model

The management of severe burns remains a complex challenge. Adenosine, lidocaine, and magnesium (ALM) resuscitation therapy has been shown to protect against hemorrhagic shock and traumatic injury. The aim of the present study was to investigate the early protective effects of small-volume ALM fluid resuscitation in a rat model of 30% total body surface area (TBSA) thermal injury. Male Sprague-Dawley rats (320-340 g; n = 25) were randomly assigned to: 1) Sham (surgical instrumentation and saline infusion, without burn, n = 5), 2) Saline resuscitation group (n = 10), or 3) ALM resuscitation group (n = 10). Treatments were initiated 15-min after burn trauma, including 0.7 mL/kg 3% NaCl ± ALM bolus and 0.25-0.5 mL/kg/h 0.9% NaCl ± ALM drip, with animals monitored to 8.25-hr post-burn. Hemodynamics, cardiac function, blood chemistry, hematology, endothelial injury markers and histopathology were assessed. Survival was 100% for Shams and 90% for both ALM and Saline groups. Shams underwent significant physiological, immune and hematological changes over time as a result of surgical traums. ALM significantly reduced malondialdehyde levels in the lungs compared to Saline (P = .023), and showed minimal alveolar destruction and inflammatory cell infiltration (P < .001). ALM also improved cardiac function and oxygen delivery (21%, P = .418 vs Saline), reduced gut injury (P < .001 vs Saline), and increased plasma adiponectin (P < .001 vs baseline). Circulating levels of the acute phase protein alpha 1-acid glycoprotein (AGP) increased 1.6-times (P < .001), which may have impacted ALM's therapeutic efficacy. We conclude that small-volume ALM therapy significantly reduced lung oxidative stress and preserved alveolar integrity following severe burn trauma. Further studies are required to assess higher ALM doses with longer monitoring periods.

Systemic immune response of burns from the acute to chronic phase

Immune responses that occur following burn injury comprise a series of reactions that are activated in response to damaged autologous tissues, followed by removal of damaged tissues and foreign pathogens such as invading bacteria, and tissue repair. These immune responses are considered to be programmed in living organisms. Developments of modern medicine have led to the saving of burned patients who could not be cured previously; however, the programmed response is no longer able to keep up, and various problems have arisen. This paper describes the mechanism of immune response specific to burn injury and the emerging concept of persistent inflammation, immunosuppression, and catabolism syndrome.

Neutrophil Count in Severe Burns Is Useful for Predicting Prognosis

Background

Burn injuries, particularly extensive severe burns, often have a fatal prognosis. However, many prognostic predictors are based on changes in the clinical course of treatment, and no prognostic predictors can be estimated in the early phases of injury. Using the Burn Index (BI) for evaluations requires familiarity with daily burn treatment, such as being able to evaluate the change from a second degree burn to a third degree burn appropriately. We sought to find a simpler and more quantitative prognostic prediction index.

Methods We hypothesized that, in addition to the current prognostic predictors, the number of neutrophils in severe burns may correlate with the prognosis, and analyzed its usefulness. The neutrophil and white blood cell counts were measured within 48 hours of injury in 35 burn patients who required inpatient treatment at our own institution. Mann-Whitney test was used to determine the significant of differences between the Survivor and Non-survivor groups.

Results

Compared to the Survivor group, neutrophil (P = 0.038) and white blood cell counts were increased significantly in the Non-survivor group (P = 0.004). Neutrophil counts and white blood cell counts correlated positively with the length of hospital stay, total body surface area, Prognostic Burn Index (PBI), and BI. The BI and PBI correlated with patient prognosis, as did neutrophil and white blood cell counts.

Conclusion

These results suggested that neutrophil and white blood cell counts in the early phases of burn injuries might be another factor in the prognosis of burn patients in addition to the current predictors.

Combination of HBA1, TTR, and SERPINF2 in plasma defines phenotype correlated with severe burn outcome

Recent advancements in proteomics allow for the concurrent identification and quantification of multiple proteins. This study aimed to identify proteins associated with severe burn pathology and establish a clinically useful molecular pathology classification. In a retrospective observational study, blood samples were collected from severe burn patients. Proteins were measured using mass spectrometry, and prognosis-related proteins were extracted by comparing survivors and non-survivors. Enrichment and ROC analyses evaluated the extracted proteins, followed by latent class analysis. Measurements were performed on 83 burn patients. In the non-survivor group, ten proteins significantly changing on the day of injury were associated with metabolic processes and toxin responses. ROC analysis identified HBA1, TTR, and SERPINF2 with AUCs > 0.8 as predictors of 28-day mortality. Latent class analysis classified three molecular pathotypes, and plasma mass spectrometry revealed ten proteins associated with severe burn prognosis. Molecular pathotypes based on HBA1, TTR, and SERPINF2 significantly correlated with outcomes.

Implications of the Regulation of Endothelial Glycocalyx Breakdown and Reconstitution in Severe Burn Injury

INTRODUCTION

Effective initial fluid resuscitation is the cornerstone intervention in the setting of severe burn injury. Critically, few major advances in burn resuscitation have been made since the 1970s, and since that time there has been only modest improvement in overall morbidity and mortality. Recently, investigations regarding the dynamic changes of vascular endothelium, and more specifically the vascular endothelial glycocalyx, in the setting of severe burn injury and resuscitation have offered insight into the possibility of more tightly controlling fluid shifts and understanding the consequences thereof during this critical period.

METHODS

We conducted a literature search of the PubMed database using the terms "burn", and "glycocalyx" limited to studies published in the English language over the past 10 y. A total of 31 articles were initially identified. Abstracts and full text were manually reviewed to identify suitable articles. Of the identified articles, 10 were deemed relevant and included within this review, along with additional articles necessary to provide background on glycocalyx structure and function as well as principles of burn injury management.

RESULTS

Glycocalyx shedding is a process known to occur early in the setting of severe burn injury and resuscitation. The degree of shedding tends to increase with age and severity of injury. Though the role and regulation of this shedding is incompletely understood, it has direct consequences on vascular unction and permeability and likely coagulation as well.

CONCLUSIONS

Here in this research review, we examine what is known regarding the dynamic breakdown and reconstitution of the glycocalyx during burn injury and how it may be impacted by fluid resuscitation strategies. We further explore the need to more completely understand this mechanism and the consequences of its manipulation.

The role of hyaluronan in endothelial glycocalyx and potential preventative lifestyle strategy with advancing age

The endothelial glycocalyx (EG) is a gel-like structure that forms a layer in between the surface of the endothelium and lumen. EG was once thought to be merely a structural support for the endothelium. However, in recent years, the importance of EG as a first line of defense and a key regulator to endothelial integrity has been illuminated. With advanced age, EG deterioration becomes more noticeable and at least partially associated with endothelial dysfunction. Hyaluronan (HA), one of the critical components of the EG, has distinct properties and roles to the maintenance of EG and endothelial function. Therefore, given the intimate relationship between the EG and endothelium during the aging process, HA may serve as a promising therapeutic target to prevent endothelial dysfunction.

The Tissue Factor Pathway in Cancer: Overview and Role of Heparan Sulfate Proteoglycans

Historically, the only focus on tissue factor (TF) in clinical pathophysiology has been on its function as the initiation of the extrinsic coagulation cascade. This obsolete vessel-wall TF dogma is now being challenged by the findings that TF circulates throughout the body as a soluble form, a cell-associated protein, and a binding microparticle. Furthermore, it has been observed that TF is expressed by various cell types, including T-lymphocytes and platelets, and that certain pathological situations, such as chronic and acute inflammatory states, and cancer, may increase its expression and activity. Transmembrane G protein-coupled protease-activated receptors can be proteolytically cleaved by the TF:FVIIa complex that develops when TF binds to Factor VII (PARs). The TF:FVIIa complex can activate integrins, receptor tyrosine kinases (RTKs), and PARs in addition to PARs. Cancer cells use these signaling pathways to promote cell division, angiogenesis, metastasis, and the maintenance of cancer stem-like cells. Proteoglycans play a crucial role in the biochemical and mechanical properties of the cellular extracellular matrix, where they control cellular behavior via interacting with transmembrane receptors. For TFPI.fXa complexes, heparan sulfate proteoglycans (HSPGs) may serve as the primary receptor for uptake and degradation. The regulation of TF expression, TF signaling mechanisms, their pathogenic effects, and their therapeutic targeting in cancer are all covered in detail here.

Shedding of the Endothelial Glycocalyx Independent of Systemic Tryptase Release during Oncologic Oral Surgery: An Observational Study

The endothelial glycocalyx and endothelial surface layer are crucial for several functions of the vasculature. Damage to the glycocalyx (“shedding”) occurs during diverse clinical conditions, including major surgery. Mast cell tryptase has been proposed as one possible “sheddase”. During oncologic oral surgery, glycocalyx shedding could be detrimental due to loss of vascular barrier function and consequent oedema in the musculocutaneous flap graft. Concentrations of the glycocalyx components heparan sulphate and syndecan-1, as well as of tryptase in blood serum before and after surgery, were measured in 16 patients undergoing oncologic oral surgery. Secondary measures were the concentrations of these substances on postoperative days 1 and 2. Heparan sulphate rose from 692 (median, interquartile range: 535–845) to 810 (638–963) ng/mL during surgery. Syndecan-1 increased from 35 (22–77) ng/mL to 138 (71–192) ng/mL. Tryptase remained virtually unchanged with 4.2 (3–5.6) before and 4.2 (2.5–5.5) ng/mL after surgery. Concentrations of heparan sulphate and syndecan-1 in serum increased during surgery, indicating glycocalyx shedding. Tryptase concentration remained equal, suggesting other sheddases than systemic tryptase release to be responsible for damage to the glycocalyx. Investigating strategies to protect the glycocalyx during oncologic oral surgery might hold potential to improve flap viability and patient outcome.

The endothelial glycocalyx in critical illness: A pediatric perspective

The vascular endothelium is the interface between circulating blood and end organs and thus has a critical role in preserving organ function. The endothelium is lined by a glycan-rich glycocalyx that uniquely contributes to endothelial function through its regulation of leukocyte and platelet interactions with the vessel wall, vascular permeability, coagulation, and vasoreactivity. Degradation of the endothelial glycocalyx can thus promote vascular dysfunction, inflammation propagation, and organ injury. The endothelial glycocalyx and its role in vascular pathophysiology has gained increasing attention over the last decade. While studies characterizing vascular glycocalyx injury and its downstream consequences in a host of adult human diseases and in animal models has burgeoned, studies evaluating glycocalyx damage in pediatric diseases are relatively few. As children have unique physiology that differs from adults, significant knowledge gaps remain in our understanding of the causes and effects of endothelial glycocalyx disintegrity in pediatric critical illness. In this narrative literature overview, we offer a unique perspective on the role of the endothelial glycocalyx in pediatric critical illness, drawing from adult and preclinical data in addition to pediatric clinical experience to elucidate how marked derangement of the endothelial surface layer may contribute to aberrant vascular biology in children. By calling attention to this nascent field, we hope to increase research efforts to address important knowledge gaps in pediatric vascular biology that may inform the development of novel therapeutic strategies.

Burn Shock and Resuscitation: Review and State of the Science

Burn shock and acute fluid resuscitation continue to spark intense interest and debate among burn clinicians. Following a major burn injury, fluid resuscitation of burn shock is life-saving, but paradoxically can also be a source of increased morbidity and mortality because of the unintended consequence of systemic edema formation. Considerable research over the past two decades has been devoted to understanding the mechanisms of edema formation, and to develop strategies to curb resuscitation fluids and limit edema development. Recognition of burn endotheliopathy - injury to the endothelium's glycocalyx layer- is one of the most important recent developments in our understanding of burn shock pathophysiology. Newer monitoring approaches and resuscitation endpoints, along with alternative resuscitation strategies to crystalloids alone, such as administration of albumin, or plasma, or high dose ascorbic acid, have had mixed results in limiting fluid creep. Clear demonstration of improvements in outcomes with all of these approaches remains elusive. This comprehensive review article on burn shock and acute resuscitation accompanies the American Burn Association's State of the Science meeting held in New Orleans, LA on November 2-3, 2021 and the Proceedings of that conference published in this journal.

A Prospective Observational Study Comparing Clinical Sepsis Criteria to Protein Biomarkers Reveals a Role for Vascular Dysfunction in Burn Sepsis

OBJECTIVES

To compare the diagnostic value of clinical sepsis criteria to novel protein biomarkers in the burn patient.

DESIGN

Prospective observational study.

SETTING

American Burn Association verified Burn Center ICU.

PATIENTS

Burn patients (n = 24) and healthy volunteers (n = 10).

INTERVENTIONS

Enrolled burn patients (n = 24) were stratified based on whether or not they met a clinical definition of sepsis. Four separate clinical criteria for sepsis were analyzed for their diagnostic sensitivity and specificity, which were compared to a panel of protein biomarkers. The most significant protein biomarkers were further analyzed via the area under the receiver operating characteristic curves (AUROCs).

MEASUREMENTS AND MAIN RESULTS

Of the clinical criteria, SEPSIS-2 criteria led to the highest AUROC (0.781; p < 0.001), followed by the quick Sequential Organ Failure Assessment score (AUROC = 0.670; p = 0.022). Multiplexing revealed a number of inflammatory proteins (complement C5) and matrix metalloproteinases (MMP1, MMP7) that were significantly elevated in septic samples compared with both healthy controls and nonseptic burn samples. Furthermore, three proteins associated with endothelial dysfunction and glycocalyx shedding revealed diagnostic potential. Specifically, syndecan-1, p-selectin, and galectin-1 were all significantly elevated in sepsis, and all resulted in an AUROC greater than 0.7; analyzing the sum of these three markers led to an AUROC of 0.808.

CONCLUSIONS

These data reveal several potential biomarkers that may help with sepsis diagnosis in the burn patient. Furthermore, the role of endotheliopathy as a mechanistic etiology for sepsis after burns warrants further investigation.

Resistin forms a network with inflammatory cytokines and is associated with prognosis in major burns

BACKGROUND

In current intensive care treatment, some patients with severe burns cannot be saved due to progressive organ failure. Further investigation of the pathogenesis of severe burns is needed to improve the mortality rate. In burns, inflammatory cytokines form a network that leads to an inflammatory response. Adipocytes secrete physiologically active substances (adipokines). The roles of adipokines have not been completely clarified in burn patients. This study aimed to determine the relation between serial changes of adipokines and clinical course in severely burned patients.

METHODS

This was a single-center, retrospective, observational study. Patients' blood samples were collected on the day of injury and around 1 week later. Adipokines (adiponectin, angiotensinogen, chemerin, CXCL-12/SDF-1, leptin, resistin, vaspin, visfatin), various inflammatory cytokines, syndecan-1 and C1 esterase inhibitor were measured.

RESULTS

Thirty-eight patients were included. Resistin levels were significantly higher in the non-survivors versus survivors on Day 1 after burn injury. Hierarchical clustering analysis showed common clusters on Day 1 and at 1 Week after burn injury (resistin, IL-6, IL-8, IL10 and MCP-1). The correlation coefficient of resistin to SOFA score at 1 Week was significant. Logistic regression analysis showed a significant relation of resistin levels on Day 1 with prognosis; the area under the ROC curve for resistin was 0.801.

CONCLUSIONS

In the acute phase of burns, resistin was associated with other pro-inflammatory cytokines and was related to the severity and prognosis of major burns.

Neutrophil-derived heparin binding protein triggers vascular leakage and synergizes with myeloperoxidase at the early stage of severe burns (With video)

Background

Burn shock caused by vascular leakage is one of the main causes of high mortality in severe burn injury. However, the pathophysiological mechanism of vascular leakage is still unclear. The purpose of this study was to explore the molecular mechanism of vascular leakage in the early stage of severe burn and provide a new target for the treatment of severe burns.

Methods

Neutrophils were isolated from human peripheral blood by magnetic beads sorting. ELISA was used to detect neutrophil-derived granule proteins and glycocalyx injury products in plasma. The vascular leakage and neutrophil movement were assessed by in vivo laser confocal imaging in mice, and high-quality video were provided.. Adhesion-related molecules were investigated by qRT-PCR. The damage to glycocalyx of mice vascular endothelial cells was observed by transmission electron microscope and scanning electron microscope. Proteomic analysis, flow cytometry and immunofluorescence were used to further study the relationship between human peripheral blood neutrophil-derived hypochlorite (HOCl) and CD44 of human vascular endothelial cells.

Results

In this study, we found that rapidly increasing activated neutrophils secrete heparin binding protein (HBP) and myeloperoxidase (MPO) after severe burn injury. Increased HBP triggers vascular leakage with synergy of MPO, results in systemic edema and burn shock. Furthermore, we found that the MPO catalytic product HOCl but not MPO triggers CD44 extracellular domain shedding from vascular endothelial cells to damage the glycocalyx. Damage to the glycocalyx results in firm adhesion of neutrophils and increases vascular leakage. However, MPO inhibitors partially protect the glycocalyx of vascular endothelial cells. The combination of HBP and MPO inhibitors markedly reduces vascular leakage and systemic edema in the early stage of severe burns.

Conclusions

Taken together, these data reveal that neutrophil-derived HBP and MPO play an important synergies role in triggering vascular leakage at the early stage of severe burns. Targeted intervention in these two biomolecules may introduce new strategies for helping to reduce large amount of fluid loss and subsequent burn shock.

Matrix Stiffness Affects Glycocalyx Expression in Cultured Endothelial Cells

Rationale: The endothelial cell glycocalyx (GCX) is a mechanosensor that plays a key role in protecting against vascular diseases. We have previously shown that age/disease mediated matrix stiffness inhibits the glycocalyx glycosaminoglycan heparan sulfate and its core protein Glypican 1 in human umbilical vein endothelial cells, rat fat pad endothelial cells and in a mouse model of age-mediated stiffness. Glypican 1 inhibition resulted in enhanced endothelial cell dysfunction. Endothelial cell culture typically occurs on stiff matrices such as plastic or glass. For the study of the endothelial GCX specifically it is important to culture cells on soft matrices to preserve GCX expression. To test the generality of this statement, we hypothesized that stiff matrices inhibit GCX expression and consequently endothelial cell function in additional cell types: bovine aortic endothelial cells, mouse aortic endothelial cell and mouse brain endothelial cells. Methods and Results: All cell types cultured on glass showed reduced GCX heparan sulfate expression compared to cells cultured on either soft polyacrylamide (PA) gels of a substrate stiffness of 2.5 kPa (mimicking the stiffness of young, healthy arteries) or on either stiff gels 10 kPa (mimicking the stiffness of old, diseased arteries). Specific cell types showed reduced expression of GCX protein Glypican 1 (4 of 5 cell types) and hyaluronic acid (2 of 5 cell types) on glass vs soft gels. Conclusion: Matrix stiffness affects GCX expression in endothelial cells. Therefore, the study of the endothelial glycocalyx on stiff matrices (glass/plastic) is not recommended for specific cell types.

Circulating Syndecan-1 and Tissue Factor Pathway Inhibitor, Biomarkers of Endothelial Dysfunction, Predict Mortality in Burn Patients

OBJECTIVE

The aim of this study is to evaluate the association between burn injury and admission plasma levels of Syndecan-1 (SDC-1) and Tissue Factor Pathway Inhibitor (TFPI), and their ability to predict 30-day mortality.

BACKGROUND

SDC-1 and TFPI are expressed by vascular endothelium and shed into the plasma as biomarkers of endothelial damage. Admission plasma biomarker levels have been associated with morbidity and mortality in trauma patients, but this has not been well characterized in burn patients.Methods: This cohort study enrolled burn patients admitted to a regional burn center between 2013 and 2017. Blood samples were collected within 4 h of admission and plasma SDC-1 and TFPI were quantified by ELISA. Demographics and injury characteristics were collected prospectively. The primary outcome was 30-day in-hospital mortality.

RESULTS

Of 158 patients, 74 met inclusion criteria. Most patients were male with median age of 41.5 years and burn TBSA of 20.5%. The overall mortality rate was 20.3%. Admission SDC-1 and TFPI were significantly higher among deceased patients. Plasma SDC-1 >34 ng/mL was associated with a 32-times higher likelihood of mortality [OR: 32.65 (95% CI, 2.67-399.78); P = 0.006] and a strong predictor of mortality (area under the ROC [AUROC] 0.92). TFPI was associated with a nine-times higher likelihood of mortality [OR: 9.59 (95% CI, 1.02-89.75); P = 0.002] and a fair predictor of mortality (AUROC 0.68).

CONCLUSIONS

SDC-1 and TFPI are associated with a higher risk of 30-day mortality. We propose the measurement of SDC-1 on admission to identify burn patients at high risk of mortality. However, further investigation with a larger sample size is warranted.

High Na+ Salt Diet and Remodeling of Vascular Smooth Muscle and Endothelial Cells

Our knowledge on essential hypertension is vast, and its treatment is well known. Not all hypertensives are salt-sensitive. The available evidence suggests that even normotensive individuals are at high cardiovascular risk and lower survival rate, as blood pressure eventually rises later in life with a high salt diet. In addition, little is known about high sodium (Na⁺) salt diet-sensitive hypertension. There is no doubt that direct and indirect Na⁺ transporters, such as the Na/Ca exchanger and the Na/H exchanger, and the Na/K pump could be implicated in the development of high salt-induced hypertension in humans. These mechanisms could be involved following the destruction of the cell membrane glycocalyx and changes in vascular endothelial and smooth muscle cells membranes’ permeability and osmolarity. Thus, it is vital to determine the membrane and intracellular mechanisms implicated in this type of hypertension and its treatment.

Resuscitative Strategies to Modulate the Endotheliopathy of Trauma: From Cell to Patient

Clinical data has supported the early use of plasma in high ratios of plasma to red cells to patients in hemorrhagic shock. The benefit from plasma seems to extend beyond its hemostatic effects to include protection to the post-shock dysfunctional endothelium. Resuscitation of the endothelium by plasma and one of its major constituents, fibrinogen, involves cell surface stabilization of syndecan-1, a transmembrane proteoglycan and the protein backbone of the endothelial glycocalyx. The pathogenic role of miRNA-19b to the endothelium is explored along with the PAK-1-mediated intracellular pathway that may link syndecan-1 to cytoskeletal protection. Additionally, clinical studies using fibrinogen and cyroprecipitate to aid in hemostasis of the bleeding patient are reviewed and new data to suggest a role for plasma and its byproducts to treat the dysfunctional endothelium associated with nonbleeding diseases is presented.

The glycocalyx core protein Glypican 1 protects vessel wall endothelial cells from stiffness-mediated dysfunction and disease

AIMS

Arterial stiffness is an underlying risk factor and a hallmark of cardiovascular diseases. The endothelial cell (EC) glycocalyx is a glycan rich surface layer that plays a key role in protecting against EC dysfunction and vascular disease. However, the mechanisms by which arterial stiffness promotes EC dysfunction and vascular disease are not fully understood, and whether the mechanism involves the protective endothelial glycocalyx is yet to be determined. We hypothesized that endothelial glycocalyx protects the endothelial cells lining the vascular wall from dysfunction and disease in response to arterial stiffness.

METHODS AND RESULTS

Cells cultured on polyacrylamide (PA) gels of substrate stiffness 10 kPa (mimicking the subendothelial stiffness of aged, unhealthy arteries) showed a significant inhibition of glycocalyx expression compared to cells cultured on softer PA gels (2.5 kPa, mimicking the subendothelial stiffness of young, healthy arteries). Specifically, gene and protein analyses revealed that a glycocalyx core protein Glypican 1 was inhibited in cells cultured on stiff PA gels. These cells had enhanced endothelial cell dysfunction as determined by enhanced cell inflammation (enhanced inflammatory gene expression, monocyte adhesion, and inhibited nitric oxide expression), proliferation, and EndMT. Removal of Glypican 1 using gene-specific silencing with siRNA or gene overexpression using a plasmid revealed that Glypican 1 is required to protect against stiffness-mediated endothelial cell dysfunction. Consistent with this, using a model of age-mediated stiffness, older mice exhibited a reduced expression of Glypican 1 and enhanced endothelial cell dysfunction compared to young mice. Glypican 1 gene deletion in knockout mice (GPC1-/-) exacerbated endothelial dysfunction in young mice, which normally had high endothelial expression, but not in old mice that normally expressed low levels. Endothelial cell dysfunction was exacerbated in young, but not aged, Glypican 1 knockout mice (GPC1-/-).

CONCLUSION

Arterial stiffness promotes EC dysfunction and vascular disease at least partly through the suppression of the glycocalyx protein Glypican 1. Glypican 1 contributes to the protection against endothelial cell dysfunction and vascular disease in endothelial cells.

Human glycocalyx shedding: Systematic review and critical appraisal

BACKGROUND

The number of studies measuring breakdown products of the glycocalyx in plasma has increased rapidly during the past decade. The purpose of the present systematic review was to assess the current knowledge concerning the association between plasma concentrations of glycocalyx components and structural assessment of the endothelium.

METHODS

We performed a literature review of Pubmed to determine which glycocalyx components change in a wide variety of human diseases and conditions. We also searched for evidence of a relationship between plasma concentrations and the thickness of the endothelial glycocalyx layer as obtained by imaging methods.

RESULTS

Out of 3,454 publications, we identified 228 that met our inclusion criteria. The vast majority demonstrate an increase in plasma glycocalyx products. Sepsis and trauma are most frequently studied, and comprise approximately 40 publications. They usually report 3-4-foldt increased levels of glycocalyx degradation products, most commonly of syndecan-1. Surgery shows a variable picture. Cardiac surgery and transplantations are most likely to involve elevations of glycocalyx degradation products. Structural assessment using imaging methods show thinning of the endothelial glycocalyx layer in cardiovascular conditions and during major surgery, but thinning does not always correlate with the plasma concentrations of glycocalyx products. The few structural assessments performed do not currently support that capillary permeability is increased when the plasma levels of glycocalyx fragments in plasma are increased.

CONCLUSIONS

Shedding of glycocalyx components is a ubiquitous process that occurs during both acute and chronic inflammation with no sensitivity or specificity for a specific disease or condition.

Elevated Plasma Concentrations of Syndecan-1 Do Not Correlate With Increased Capillary Leakage of 20% Albumin

BACKGROUND

Preclinical experiments show that an inflammatory reaction causes degradation of the endothelial glycocalyx layer and accelerated capillary leakage of albumin and fluid. The hypothesis in the present study was that elevated plasma concentrations of glycocalyx degradation products are associated with greater capillary leakage in humans.

METHODS

This open clinical trial involved administration of an intravenous infusion of 20% albumin at 3 mL/kg over 30 minutes to 15 postburn patients who showed an activated inflammatory response. Blood samples and urine were collected for 300 minutes. The plasma concentrations of 2 biomarkers of glycocalyx degradation-syndecan-1 and heparan sulfate-were measured at 0, 60, and 300 minutes and compared to the capillary leakage of albumin and fluid obtained by mass balance calculations and population kinetic analysis.

RESULTS

Patients were studied at 7 days (median) after a burn injury that covered 15% (maximum 48%) of the body surface area. The median plasma syndecan-1 concentration was 71 (25th-75th percentiles, 41-185) ng/mL. The 2 patients with highest values showed 2279 and 2395 ng/mL (normal 15 ng/mL). Heparan sulfate concentrations averaged 915 (673-1539) ng/mL. The infused amount of albumin was 57 (48-62) g, and 6.3 (5.1-7.7)% of that leaked from the plasma per hour.Linear correlation analysis of the relationship between the 10logarithm of the mean syndecan-1 and the albumin leakage showed a slope coefficient of -1.3 (95% confidence interval [CI], -3.6 to 1.0) and a correlation coefficient of -0.33 (P = .24). The kinetic analysis revealed that syndecan-1 served as a statistically significant covariate to the albumin leakage, but the relationship was inverse (power exponent -0.78, 95% CI, -1.50 to -0.05; P < .02). Heparan sulfate levels did not correlate with the capillary leakage of albumin or fluid in any of the analyses.

CONCLUSIONS

A raised plasma concentration of syndecan-1 alone cannot be extrapolated to indicate increased capillary leakage of albumin and fluid.

Plasma syndecan-1 is associated with fluid requirements and clinical outcomes in emergency department patients with sepsis

BACKGROUND

Degradation of the endothelial glycocalyx is recognized as a major part of the pathophysiology of sepsis. Previous clinical studies, mostly conducted in intensive care settings, showed associations between glycocalyx shedding and clinical outcomes. We aimed to explore the association of plasma syndecan-1, a marker of glycocalyx degradation, with the subsequent fluid requirements and clinical outcomes of emergency department patients with sepsis.

METHODS

This was a post hoc analysis of a randomized trial of fluid resuscitation in the emergency department. The study was conducted in the emergency department of an urban 1500-bed tertiary care center. The data of 95 adults who were diagnosed with sepsis-induced hypoperfusion and had undergone baseline syndecan-1 measurement were included. The syndecan-1 levels at baseline (T0) and hour 6 (T6) were studied to characterize their association with clinical outcomes, including subsequent fluid administration, organ failure outcomes and mortality.

RESULTS

The median syndecan-1 levels at T0 and T6 were 207 (IQR 135-438) and 207 (IQR 128-490) ng/ml, respectively. Syndecan-1 levels at T0 were correlated with baseline sequential organ failure assessment (SOFA) score (ρ = 0.35, p < 0.001). Syndecan-1 levels at both T0 and T6 were correlated with subsequent fluid administration over 24 and 72 h and associated with the diagnosis of septic shock, the maximum dose of vasopressors and the need for renal replacement therapy (p < 0.05). Higher syndecan-1 levels at T6 were associated with higher 90-day mortality (p = 0.03).

CONCLUSIONS

In the emergency department, syndecan-1 levels were associated with fluid requirements, sepsis severity, organ dysfunction, and mortality.

Low-soluble TREM-like transcript-1 levels early after severe burn reflect increased coagulation disorders and predict 30-day mortality

BACKGROUND

Patients with severe burns often show systemic coagulation changes in the early stage and even develop extensive coagulopathy. Previous studies have confirmed that soluble TREM-like transcript-1 (sTLT-1) mediates a novel mechanism of haemostasis and thrombosis in inflammatory vascular injury. At present, the role of sTLT-1 in patients with severe burns is not well known.

OBJECTIVE

To investigate the early association between sTLT-1 levels and markers of burn severity, coagulation disorders, endothelial permeability, shock and prognosis in patients with severe burns.

METHODS

A prospective, observational study was conducted with 60 severe burn patients (divided into a death group and a survival group according to 30-day prognosis) admitted to our hospital. Twenty-eight healthy volunteers were recruited as the control group. Blood components at 48 h after burn were analysed for sTLT-1 and biomarkers reflecting platelet activation, shock, endothelial glycocalyx damage, capillary leakage, haemostasis, fibrinolytic activity, natural anticoagulation and blood cells. We compared the three groups, analysed the correlation between sTLT-1 and biomarkers, and investigated the predictive value of sTLT-1 for 30-day prognosis.

RESULT

Compared with the surviving patients, the patients who died had a lower degree of platelet activation [lower sTLT-1, platelet factor 4 (PF-4) and platelet counts] and a higher degree of burn [higher abbreviated burn severity index score (ABSI score)], shock (higher lactate), endothelial glycocalyx damage [higher syndecan-1 and soluble thrombomodulin (sTM)] and capillary leakage [higher resuscitation fluid (0-48 h), lower albumin] as well as decreased haemostasis [higher activated partial prothrombin time (APTT), lower fibrinogen and thrombin-antithrombin III complex (TAT)], increased fibrinolytic activity [higher D-dimer and tissue-type plasminogen activator (tPA)] and decreased natural anticoagulation [lower protein C (PC) and protein S (PS)]. Higher D-dimer (P = 0.013) and lower PF-4 (P = 0.001) were significantly independently associated with lower sTLT-1. Low circulating sTLT-1 (a unit is 50 pg/mL) (odds ratio [OR] 2.08 [95% CI 1.11-3.92], P = 0.022) was an independent predictor of increased 30-day mortality.

CONCLUSION

Low sTLT-1 levels at 48 h after burn in patients with severe burns is associated with increased coagulation disorders. Low circulating sTLT-1 levels were an independent predictor of increased 30-day mortality.

C1 Esterase Inhibitor Activity Is Reduced in the Acute Phase Following Burn Injury: A Prospective Observational Study

Hereditary angioedema has been attributed to an inherited deficiency of C1 esterase inhibitor that increases vascular permeability. The role of C1 esterase inhibitor in burn patients has not been described previously. In this study, we attempted to identify the relationship between serial changes of C1 esterase inhibitor activity and the clinical course in major burn patients. This study was a single-center, prospective, observational study. C1 esterase inhibitor activity values were serially examined in major burn patients admitted into the burn center from April 2014 to December 2016. Inclusion criteria were age ≥16 years old and %TBSA burned ≥20%. This study included 38 patients with major burn. C1 esterase inhibitor activity after burn dropped acutely on days 1 and 2 but increased immediately until days 3 to 5, after which it continued to gradually increase to above the reference value. C1 esterase inhibitor activity on admission showed significant inverse correlation with the volume of infusion per body weight required in the first 24 hours after injury and %TBSA burned (r = -0.405, P = 0.01; r = -0.375, P = 0.02, respectively). C1 esterase inhibitor activity on admission was significantly lower in the nonsurvivors than in the survivors during the 28-day evaluation period (59% vs 90%, P = 0.01). These findings suggest that C1 esterase inhibitor may play a critical role in regulating vascular permeability in the acute phase following the burn injury.

Is the Parkland formula still the best method for determining the fluid resuscitation volume in adults for the first 24 hours after injury? - A retrospective analysis of burn patients in Germany

BACKGROUND

R Rapid fluid resuscitation is a crucial therapy during the treatment of patients with extensive burns. In 1968, the Parkland Formula was introduced for the calculation of the estimated volume of the resuscitation fluid. Since then, different methods for the calculation of fluid resuscitation volume have been developed. We aimed to evaluate if the Parkland formula is still the most effective method for fluid resuscitation volume calculation in burn patients.

METHODS

In the period between January 2015 and January 2019, data from 569 patients over 16 years old with burns of more than 20% total body surface area (TBSA) and at least 15% TBSA full thickness burns were entered in the German burn registry. The patients were divided into 5 groups (0, +1, -1, +2, -2) according to the volume of the resuscitation fluid they received. Group 0 patients received the amount of fluid calculated according to the Parkland formula (n = 83). The 4 other groups received reduced (-1, -2) or increased (+1, +2) fluid volumes in comparison to the value obtained by the Parkland formula.

RESULTS

Patients in Group 0 presented a significantly lower mortality in the first week (4.5%) compared to groups -2 (16.7%) and group +2 (19.5%) (p = 0.021). Furthermore, the mean number of operations in group +2 (5.81) was higher than in group -2 (3.81). Surviving patients from group +2 presented a longer hospital stay (68.1 days) compared to the other groups. Additionally, the logistic regression analysis showed a higher survival of patients in groups -2 and -1 (regression coefficients -0.11 and -0.086; Odds Ratio 0.896 and 0.918; 95% Confidence Interval (CI) 0,411-1.951 and 0.42-2.004).

CONCLUSION

In this retrospective study, register based analysis a restrictive fluid regime was associated with a higher survival compared to the liberal Parkland guided fluid regime.

Influence of burn severity on endothelial glycocalyx shedding following thermal trauma: A prospective observational study

OBJECTIVE

Severe burns cause hypermetabolic and inflammatory responses are treated with significant volume resuscitation. This study aimed to evaluate correlations between glycocalyx metabolites and the burn size as well as certain clinical parameters such as administered fluid volumes.

STUDY DESIGN

Severely burned patients with a total body surface area (TBSA) burned smaller and larger than 20% were included. Clinical parameters including length of stay, mortality, fluid administration and Sequential Organ Failure Assessment (SOFA) score as well as syndecan and heparansulfate, as laboratory parameters for endothelial damage, were obtained.

RESULTS

A total of 39 patients (32 males, 7 females) with a mean age at burn of 45 ± 21 years were included. Syndecan levels decreased and heparansulfate levels increased over time. In both heparansulfate and syndecan, there was no significant difference between burns smaller and larger than 20% TBSA at any time point. Syndecan levels at 24 h after burn correlated significantly with IL-10 levels at admission (R = 0.58 and p < 0.05). There were significant linear correlations of %TBSA and cumulative administration of fluids after 24 h on syndecan levels after 48 h. Correlations between clinical parameters and syndecan or heparansulfate levels over time were not found.

CONCLUSIONS

This study shows that even though there are moderate correlations with burn size and administered fluid volume, levels of syndecan and heparansulfate are not predictive for clinical outcomes of burned patients in our cohort. Further studies with higher numbers evaluating the effect of large burns on glycocalyx shedding over a longer period of time are needed. Showing significant glycocalyx shedding in large burn including potentially correlations with clinical outcomes may yield new therapeutic targets.

1.2% Hydrogen gas inhalation protects the endothelial glycocalyx during hemorrhagic shock: a prospective laboratory study in rats

PURPOSE

Hydrogen gas (H₂) inhalation improved the survival rate of hemorrhagic shock. However, its mechanisms are unknown. We hypothesized that H₂ protected the endothelial glycocalyx during hemorrhagic shock and prolonged survival time.

METHODS

83 Sprague-Dawley rats were anesthetized with isoflurane. The animals were randomly assigned to 5 groups: room air with no shock, 1.2% H₂ with no shock, room air with shock (Control-S), 1.2% H₂ with shock (H₂1.2%-S), and 3.0% H₂ with shock (H₂3.0%-S). Shock groups were bled to a mean arterial pressure of 30-35 mmHg and held for 60 min, then resuscitated with normal saline at fourfold the amount of the shed blood volume.

RESULTS

The syndecan-1 level was significantly lower in the H₂1.2%-S [8.3 ± 6.6 ng/ml; P = 0.01; 95% confidence interval (CI), 3.2-35.8] than in the Control-S (27.9 ± 17.0 ng/ml). The endothelial glycocalyx was significantly thicker in the H₂1.2%-S (0.15 ± 0.02 µm; P = 0.007; 95% CI, 0.02-0.2) than in the Control-S (0.06 ± 0.02 µm). The survival time was longer in the H₂1.2%-S (327 ± 67 min, P = 0.0160) than in the Control-S (246 ± 69 min). The hemoglobin level was significantly lower in the H₂1.2%-S (9.4 ± 0.5 g/dl; P = 0.0034; 95% CI, 0.6-2.9) than in the Control-S (11.1 ± 0.8 g/dl). However, the H₂3.0%-S was not significant.

CONCLUSIONS

Inhalation of 1.2% H₂ gas protected the endothelial glycocalyx and prolonged survival time during hemorrhagic shock. Therapeutic efficacy might vary depending on the concentration.

Endothelial glycocalyx in acute care surgery - what anaesthesiologists need to know for clinical practice

The endothelial glycocalyx (EG) is the thin sugar-based lining on the apical surface of endothelial cells. It has been linked to the physiological functioning of the microcirculation and has been found to be damaged in critical illness and after acute care surgery. This review aims to describe the role of EG in severely injured patients undergoing surgery, discuss specific situations (e.G. major trauma, hemorrhagic shock, trauma induced coagulopathy) as well as specific interventions commonly applied in these patients (e.g. fluid therapy, transfusion) and specific drugs related to perioperative medicine with regard to their impact on EG.EG in acute care surgery is exposed to damage due to tissue trauma, inflammation, oxidative stress and inadequate fluid therapy. Even though some interventions (transfusion of plasma, human serum albumin, hydrocortisone, sevoflurane) are described as potentially EG protective there is still no specific treatment for EG protection and recovery in clinical medicine.The most important principle to be adopted in routine clinical practice at present is to acknowledge the fragile structure of the EG and avoid further damage which is potentially related to worsened clinical outcome.

A Critical Update of the Assessment and Acute Management of Patients with Severe Burns

Significance: Burns are debilitating, life threatening, and difficult to assess and manage. Recent advances in assessment and management have occurred since a comprehensive review of the care of patients with severe burns was last published, which may influence research and clinical practice. Recent Advances: Recent advances have occurred in the understanding of burn pathophysiology, which has led to the identification of potential biomarkers of burn severity, such as protein C. There is new evidence about the potential superiority of natural colloids over crystalloids during fluid resuscitation, and new evidence about components of initial and perioperative management, including an improved understanding of pain following burns. Critical Issues: The limitations of the clinical examination highlight the need for imaging and biomarkers to assist in estimations of burn severity. Fluid resuscitation reduces mortality, although there is conjecture over the ideal method. The subsequent perioperative period is associated with significant morbidity and the evidence for preventing and treating pain, infection, and fluid overload while maximizing wound healing potential is described. Future Directions: Promising developments are ongoing in imaging technology, histopathology, biomarkers, and wound healing adjuncts such as hyperbaric oxygen therapy, topical negative pressure therapy, stem cell treatments, and skin substitutes. The greatest benefit from further research on management of patients with burns would most likely be derived from the elucidation of optimal fluid resuscitation protocols, pain management protocols, and surgical techniques from randomized controlled trials.

Plasma for burn shock resuscitation: is it time to go back to the future?

Patients with burn shock can be challenging to resuscitate. Burn shock produces a variety of physiologic derangements: Patients are hypovolemic from volume loss, have a increased systemic vascular resistance, and may have a depressed cardiac output depending on the extent of the thermal injury. Additionally, the burn wound produces a significant inflammatory cascade of events that contributes to the shock state. Fluid resuscitation is foundational for the initial treatment of burn shock. Typical resuscitation is with intravenous lactated Ringer's in accordance with well-established formulas based on burn wound size. In the past century, as therapies to treat thermal injuries were being developed, plasma was the fluid used for burn resuscitation; in fact, plasma was used in World War II and throughout the 1950s and 1960s. Plasma was abandoned because of infectious risks and complications. Despite huge strides in transfusion medicine and the increased safety of blood products, plasma has never been readopted for burn resuscitation. Over the past 15 years, there has been a paradigm shift in trauma resuscitation: Less crystalloid and more blood products are used; this strategy has demonstrated improved outcomes. Plasma is a physiologic fluid that stabilizes the endothelium. The endotheliopathy of trauma has been described and is mitigated by transfusion strategies with a 1:1 ratio of RBCs to plasma. Thermal injury also results in endothelial dysfunction: the endotheliopathy of burns. Plasma is likely a better resuscitation fluid for patients with significant burn wounds because of its capability to restore intravascular volume status and treat the endotheliopathy of burns.

On-the-Scene Hyaluronan and Syndecan-1 Serum Concentrations and Outcome after Cardiac Arrest and Resuscitation

Background

It is not predictable which patients will develop a severe inflammatory response after successful cardiopulmonary resuscitation (CPR), also known as “postcardiac arrest syndrome.” This pathology affects only a subgroup of cardiac arrest victims. Whole body ischemia/reperfusion and prolonged shock states after return of spontaneous circulation (ROSC) may both contribute to this devastating condition. The vascular endothelium with its glycocalyx is especially susceptible to initial ischemic damage and may play a detrimental role in the initiation of postischemic inflammatory reactions. It is not known to date if an immediate early damage to the endothelial glycocalyx, detected by on-the-scene blood sampling and measurement of soluble components (hyaluronan and syndecan-1), precedes and predicts multiple organ failure (MOF) and survival after ROSC.

Methods

15 patients after prehospital resuscitation were included in the study. Serum samples were collected on the scene immediately after ROSC and after 6 h, 12 h, 24 h, and 48 h. Hyaluronan and syndecan-1 were measured by ELISA. We associated the development of multiple organ failure and 30-day survival rates with these serum markers of early glycocalyx damage.

Results

Immediate serum hyaluronan concentrations show significant differences depending on 30-day survival. Further, the hyaluronan level is significantly higher in patients developing MOF during the initial and intermediate resuscitation period. Also, the syndecan-1 levels are significantly different according to MOF occurrence.

Conclusion

Serum markers of glycocalyx shedding taken immediately on the scene after ROSC can predict the occurrence of multiple organ failure and adverse clinical outcome in patients after cardiac arrest.

Early Hemodynamic Management of Critically Ill Burn Patients

The challenge of initial hemodynamic resuscitation of severe burn patients is in avoiding under- and over-resuscitation associated with bad outcome. This review aims to propose strategies for the initial hemodynamic management of severe burns.

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