The Endothelial Glycocalyx: A Fundamental Determinant of Vascular Permeability in Sepsis

The Mechanisms of Sepsis Induced Coagulation Dysfunction and Its Treatment

Sepsis is a critical condition characterized by organ dysfunction due to a dysregulated response to infection that poses significant global health challenges. Coagulation dysfunction is nearly ubiquitous among sepsis patients. Its mechanisms involve platelet activation, coagulation cascade activation, inflammatory reaction imbalances, immune dysregulation, mitochondrial damage, neuroendocrine network disruptions, and endoplasmic reticulum (ER) stress. These factors not only interact but also exacerbate one another, leading to severe organ dysfunction. This review illustrates the mechanisms of sepsis-induced coagulopathy, with a focus on tissue factor activation, endothelial glycocalyx damage, and the release of neutrophil extracellular traps (NETs), all of which are potential targets for therapeutic interventions.

Unveiling key predictors of sepsis mortality in intermediate care units: a decision tree study

BACKGROUND

Sepsis remains a leading cause of mortality, especially among patients admitted to non-ICU settings like intermediate care units (IMCUs). Current prognostic tools have limitations in predicting outcomes in these patients. This study aimed to identify key predictors of mortality using decision tree analysis.

METHODS

We conducted a prospective observational study from January 2023 to June 2024, enrolling 254 septic patients admitted to the IMCU of Santorso Hospital, Italy. Clinical, laboratory, and demographic data were collected, and decision tree analysis was performed to identify factors associated with 30-day mortality. Variables were compared using univariate and multivariate analyses, and significant predictors were incorporated into the decision tree model.

RESULTS

The 30-day mortality rate was 14.6%. Serum albumin was identified as the root node of the decision tree, with lower levels (≤2.3 g/dL) strongly associated with mortality. Additional predictors were identified as higher NEWS scores (OR 1.153, p = 0.002) and older age (OR 1.062, p = 0.021). Traditional scoring systems like SOFA and APACHE did not significantly predict outcomes in this setting.

CONCLUSIONS

Serum albumin is a key prognostic marker in septic patients admitted to IMCUs, alongside NEWS and age. These findings suggest that albumin levels at admission may aid in early risk stratification and clinical decision-making in non-ICU environments. Future studies should validate these results across different healthcare settings to optimize sepsis management.

Continuous renal replacement therapy with vitamin E-coated polysulfone hemofilter reduces inflammatory responses in a porcine lipopolysaccharide-treated model

INTRODUCTION

Biological invasions may promote the onset of systemic inflammatory response syndrome in patients eligible for continuous renal replacement therapy (CRRT), leading to poor prognosis. Hence, we aimed to examine the inflammatory reactions in circulation using vitamin E-coated polysulfone hollow fiber membrane (ViLIFE).

METHODS

Lipopolysaccharides were intravenously administered to pigs (2 μg/kg/30 min) to establish an acute inflammation model. Extracorporeal circulation was performed for 6 h in continuous venovenous hemodiafiltration mode using a hemofilter for CRRT filled with a polysulfone hollow fiber membrane or ViLIFE, and the differences in inflammatory reactions were evaluated.

RESULTS

The ViLIFE group exhibited low platelet and cytokine levels (p < 0.05 vs. sham-CRRT group). Additionally, the ViLIFE group had lower lactate and high mobility group box 1 levels than the other groups.

CONCLUSION

ViLIFE represents a promising CRRT modality that can inhibit the inflammatory response in circulation and inhibit further biological invasions.

Dipeptidyl peptidase-4 inhibitor linagliptin reduces inflammatory response, ameliorates tissue edema formation, and improves survival in severe sepsis

BACKGROUND

Excessive inflammation in sepsis causes microvascular dysfunction associated with organ dysfunction and high mortality. The present studies aimed to examine the therapeutic potential of linagliptin, a dipeptidyl peptidase-4 (DPP-4) inhibitor in a clinically relevant polymicrobial sepsis model in mice.

METHODS

Sepsis was induced by cecal ligation and puncture (CLP). Mice were grouped into: Sham control+vehicle; Group 2: CLP+vehicle; Group 3: CLP+dexamethasone (10 mg/kg, s.c.) given 6 h after CLP; Group 4: CLP+linagliptin (1 mg/kg, s.c.) given 6 h after CLP. The experiment was terminated 24 hours after CLP in two experimental sets. Seven-day survival following CLP was determined in a third experimental set.

RESULTS

Treatment with linagliptin inhibited DPP-4 activity, increased the levels of active forms of endogenous gastric inhibitory polypeptide and glucagon-like peptide-1, without affecting the blood glucose levels in CLP mice. Compared to vehicle treatment, administration of linagliptin reduced sepsis-induced tissue hyper permeability as evidenced by a reduction in vascular Evans blue leakage, prevented edema formation in the lung, heart, liver and kidney. Furthermore, linagliptin or dexamethasone reduced sepsis-induced proinflammatory cytokine and chemokine production, such as IL-1β, IL-2, IL-10, IL-23, IL-27, VCAM-1, eotaxin, MDC, MCSF1, GCP-2, and NGAL. Importantly, administration of linagliptin improved the 7-day survival rate following CLP in mice. RNA sequencing in lung and heart revealed that linagliptin attenuated key inflammatory pathways including TNF alpha (via NFκB) and IL6/JAK/STAT3 signaling and activated interferon signaling in the heart.

CONCLUSIONS

Linagliptin treatment can attenuate the inflammatory response, protect against severe sepsis-induced vascular hyperpermeability, reduce multiorgan injury, and most importantly, improve the survival.

Characterization of microcirculatory endothelial functions in a D-Galactose-induced aging model

BACKGROUND

Microcirculation health is critical to human health, and aging is an important factor affecting microcirculation health. Although D-Galactose has been widely used in aging research models, there is a lack of relevant studies on D-Galactose simulating microcirculatory aging. Here, we explored microcirculatory endothelial function in D-Galactose-induced aging mice.

METHODS

Intraperitoneal injection of 150 mg/(kg·d) of D-Galactose was given to cause senescence in mice. Aging was evaluated by SA-β-gal (senescence-associated β-galactosidase) staining. The auricular skin and hepatic microcirculation of mice were observed and detected by enzyme-linked immunosorbent assay (ELISA), immunohistochemistry (IHC) and microcirculation apparatus. The aging of microcirculation was analyzed from oxidative stress, endothelial impairment, inflammation, microvascular morphology and hemodynamics.

RESULTS

In aging mice, percentage of SA-β-gal positive area, oxidative stress products reactive oxygen species (ROS) and nitric oxide (NO), endothelial impairment marker syndecan-1 (SDC-1), stromal cell derived factor-1 (SDF-1), intercellular cell adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) in the senescence-associated secretory phenotype (SASP) were all up-regulated. The tortuosity of microvessels increased in aging mice, the linear density did not change significantly, but the total length of narrow microvessels (TLNMV) increased and wide microvessels (TLWMV) decreased, speculate that vasomotor dysfunction may be present. Hemodynamically, both perfusion and velocity of blood flow were reduced in senescent mice, presumably due to endothelial dysfunction.

CONCLUSION

Microcirculatory endothelial dysfunction is induced by D-Galactose, leading to microcirculatory aging. In vivo, this is manifested by elevated levels of oxidative stress, impaired endothelial glycocalyx (eGC), and a greater production of chemokines and adhesive molecules. These changes cause vasomotor dysfunction and remodeling, ultimately leading to hemodynamic impairment.

The anti-inflammatory effects of Fuzapladib in an endotoxemic porcine model

Endotoxemia is a systemic inflammatory condition caused by lipopolysaccharide (LPS) stimulation, which produces inflammatory cytokines. Fuzapladib (FZP) inhibits the activation of adhesion molecules found on the surface of inflammatory cells, mitigating inflammation. In this study, we evaluated the therapeutic effects of fuzapladib on inflammatory cytokines and cardio-respiratory function using an LPS-induced endotoxemic porcine model. Fifteen pigs were separated into three groups: low-FZP (n=5), high-FZP (n=5), and control (n=5). Pigs were administered LPS under general anesthesia, and complete blood cell count, blood biochemistry, inflammatory cytokines, and cardio-respiratory function were evaluated. Statistical analysis was performed using a linear mixed-effects model and the Steel-Dwass test, with a significance threshold of P<0.05. During the 4 hr experimental period, one pig in the control group and two pigs in the low-FZP group died due to hypoxemia and hypotension. In the early acute changes following LPS administration, the high-FZP group maintained significantly higher arterial oxygen partial pressure and normal blood pressure compared to the control group. Although interleukin-6 levels increased in all groups during the experiment, they were significantly lower in the high-FZP group compared to the control group. Other parameters showed no clinically significant differences. In conclusion, while high-dose fuzapladib did not reduce organ damage in the porcine endotoxemia model, it suppressed interleukin-6 production, delayed the progression of deterioration, and contributed to a reduction in mortality during the observation period.

Immunological alterations in the endothelial barrier: a new predictive and therapeutic paradigm for sepsis

INTRODUCTION

Despite the fact incidence and mortality vary widely among regions, sepsis remains a major cause of morbidity and cost worldwide. The importance of the endothelial barrier in sepsis and infectious diseases is increasingly recognized; however, the underlying pathophysiology of the endothelial barrier in sepsis remains poorly understood.

AREAS COVERED

Here we review the advances in basic and clinical research for relevant papers in PubMed database. We attempt to provide an updated overview of immunological alterations in endothelial dysfunction, discussing the central role of endothelial barrier involved in sepsis to provide new predictive and therapeutic paradigm for sepsis.

EXPERT OPINION

Given its physiological and immunological functions in infectious diseases, the endothelial barrier has been dramatically altered in sepsis, suggesting that endothelial dysfunction may play a critical role in the pathogenesis of sepsis. Although many reliable biomarkers have been investigated to monitor endothelial activation and injury in an attempt to find diagnostic and therapeutic tools, there are no specific therapies to treat sepsis due to its complex pathophysiology. Since sepsis is initiated by both hyperinflammation and immunoparalysis occurring simultaneously, a 'one-treatment-fits-all' strategy for sepsis-induced immune injury and immunoparalysis is bound to fail, and an individualized 'precision medicine' approach is required.

Dynamics of Endothelial Cell Diversity and Plasticity in Health and Disease

Endothelial cells (ECs) are vital structural units of the cardiovascular system possessing two principal distinctive properties: heterogeneity and plasticity. Endothelial heterogeneity is defined by differences in tissue-specific endothelial phenotypes and their high predisposition to modification along the length of the vascular bed. This aspect of heterogeneity is closely associated with plasticity, the ability of ECs to adapt to environmental cues through the mobilization of genetic, molecular, and structural alterations. The specific endothelial cytoarchitectonics facilitate a quick structural cell reorganization and, furthermore, easy adaptation to the extrinsic and intrinsic environmental stimuli, known as the epigenetic landscape. ECs, as universally distributed and ubiquitous cells of the human body, play a role that extends far beyond their structural function in the cardiovascular system. They play a crucial role in terms of barrier function, cell-to-cell communication, and a myriad of physiological and pathologic processes. These include development, ontogenesis, disease initiation, and progression, as well as growth, regeneration, and repair. Despite substantial progress in the understanding of endothelial cell biology, the role of ECs in healthy conditions and pathologies remains a fascinating area of exploration. This review aims to summarize knowledge and concepts in endothelial biology. It focuses on the development and functional characteristics of endothelial cells in health and pathological conditions, with a particular emphasis on endothelial phenotypic and functional heterogeneity.

Rapid cellular uptake of citrate-coated iron oxide nanoparticles unaffected by cell-surface glycosaminoglycans

Citrate-coated iron oxide nanoparticles, specifically Synomag®-COOH (SynC), are promising tracers in magnetic particle imaging (MPI) due to their high magnetic moments and rapid cellular uptake. The mechanisms driving efficient SynC uptake remain unclear. Previous observations suggest a role of the extracellular glycocalyx during nanoparticle uptake. Here, we ascertain whether the cell-surface glycosaminoglycans (GAGs) regulate the uptake of SynC. Using transmission electron microscopy (TEM), we visualized SynC uptake by THP-1 cells, a human acute monocytic leukemia cell line. We investigated the interaction of SynC with GAGs in living cells using click-chemistry-based labeling. Upon treating THP-1 cells with chondroitinase or hyaluronidase and with a xylosyltransferase-deficient cell line, we quantified SynC uptake and measured interactions of SynC with cells in real time using magnetic particle spectroscopy (MPS). The THP-1 cell membrane engulfed or formed extensions around SynC, indicating uptake through pinocytosis and phagocytosis. We measured an increased MPS signal of SynC within seconds of cell contact, suggesting an interaction with extracellular components like the glycocalyx. Upon adding SynC to THP-1 cells, we could not observe disruption of fluorescently labeled GAGs or an enhanced intracellular fluorescence, implying that SynC does not accelerate the turnover of GAGs by binding. Lack of chondroitin sulfate, heparan sulfate, and hyaluronic acid did not affect the rapid magnetic behavior increase of SynC upon cell contact. Accordingly, we measured no significant differences in SynC uptake between wild type cells and our GAG-deficient models. These findings suggest that GAGs act as a permeable bandpass for SynC nanoparticles with a minor negative surface charge of -13.8 mV. This finding has significant implications for MPI-based cell tracking because it facilitates efficient tracking of cell types that lack a strong repulsion by cell-surface GAGs. It will be crucial to investigate whether the rapid uptake of SynC is cell-type specific and influenced by different extracellular matrix compositions.

Glycosaminoglycans: Participants in Microvascular Coagulation of Sepsis

Sepsis represents a syndromic response to infection and frequently acts as a common pathway leading to fatality in the context of various infectious diseases globally. The pathology of severe sepsis is marked by an excess of inflammation and activated coagulation. A substantial contributor to mortality in sepsis patients is widespread microvascular thrombosis-induced organ dysfunction. Multiple lines of evidence support the notion that sepsis induces endothelial damage, leading to the release of glycosaminoglycans, potentially causing microvascular dysfunction. This review aims to initially elucidate the relationship among endothelial damage, excessive inflammation, and thrombosis in sepsis. Following this, we present a summary of the involvement of glycosaminoglycans in coagulation, elucidating interactions among glycosaminoglycans, platelets, and inflammatory cells. In this section, we also introduce a reasoned generalization of potential signal pathways wherein glycosaminoglycans play a role in clotting. Finally, we discuss current methods for detecting microvascular conditions in sepsis patients from the perspective of glycosaminoglycans. In conclusion, it is imperative to pay closer attention to the role of glycosaminoglycans in the mechanism of microvascular thrombosis in sepsis. Dynamically assessing glycosaminoglycan levels in patients may aid in predicting microvascular conditions, enabling the monitoring of disease progression, adjustment of clinical treatment schemes, and mitigation of both acute and long-term adverse outcomes associated with sepsis.

Vascular leak in sepsis: physiological basis and potential therapeutic advances

Sepsis is a life-threatening condition characterised by endothelial barrier dysfunction and impairment of normal microcirculatory function, resulting in a state of hypoperfusion and tissue oedema. No specific pharmacological therapies are currently used to attenuate microvascular injury. Given the prominent role of endothelial breakdown and microcirculatory dysfunction in sepsis, there is a need for effective strategies to protect the endothelium. In this review we will discuss key mechanisms and putative therapeutic agents relevant to endothelial barrier function.

Endothelial Glycocalyx Degradation Patterns in Sepsis-Associated Pediatric Acute Respiratory Distress Syndrome: A Single Center Retrospective Observational Study

BACKGROUND

Sepsis-associated destruction of the pulmonary microvascular endothelial glycocalyx (EGCX) creates a vulnerable endothelial surface, contributing to the development of acute respiratory distress syndrome (ARDS). Constituents of the EGCX shed into circulation, glycosaminoglycans and proteoglycans, may serve as biomarkers of endothelial dysfunction. We sought to define the patterns of plasma EGCX degradation products in children with sepsis-associated pediatric ARDS (PARDS), and test their association with clinical outcomes.

METHODS

We retrospectively analyzed a prospective cohort (2018-2020) of children (≥1 month to <18 years of age) receiving invasive mechanical ventilation for acute respiratory failure for ≥72 h. Children with and without sepsis-associated PARDS were selected from the parent cohort and compared. Blood was collected at time of enrollment. Plasma glycosaminoglycan disaccharide class (heparan sulfate, chondroitin sulfate, and hyaluronan) and sulfation subtypes (heparan sulfate and chondroitin sulfate) were quantified using liquid chromatography tandem mass spectrometry. Plasma proteoglycans (syndecan-1) were measured through an immunoassay.

RESULTS

Among the 39 mechanically ventilated children (29 with and 10 without sepsis-associated PARDS), sepsis-associated PARDS patients demonstrated higher levels of heparan sulfate (median 639 ng/mL [interquartile range, IQR 421-902] vs 311 [IQR 228-461]) and syndecan-1 (median 146 ng/mL [IQR 32-315] vs 8 [IQR 8-50]), both p = 0.01. Heparan sulfate subtype analysis demonstrated greater proportions of N-sulfated disaccharide levels among children with sepsis-associated PARDS (p = 0.01). Increasing N-sulfated disaccharide levels by quartile were associated with severe PARDS (n = 9/29) with the highest quartile including >60% of the severe PARDS patients (test for trend, p = 0.04). Higher total heparan sulfate and N-sulfated disaccharide levels were independently associated with fewer 28-day ventilator-free days in children with sepsis-associated PARDS (all p < 0.05).

CONCLUSIONS

Children with sepsis-associated PARDS exhibited higher plasma levels of heparan sulfate disaccharides and syndecan-1, suggesting that EGCX degradation biomarkers may provide insights into endothelial dysfunction and PARDS pathobiology.

Association between fluid overload and mortality in children with sepsis: a systematic review and meta-analysis

BACKGROUND

Sepsis is one of the main causes of morbidity and mortality worldwide. Fluid resuscitation is among the most common interventions and is associated with fluid overload (FO) in some patients. The objective of this systematic review and meta-analysis was to summarise the available evidence on the association between FO and morbimortality in children with sepsis.

METHODS

A systematic search was carried out in PubMed/Medline, Embase, Cochrane and Google Scholar up to December 2022 (PROSPERO 408148), including studies in children with sepsis which reported more than 10% FO 24 hours after admission to intensive care. The risk of bias was assessed using the Newcastle-Ottawa scale. Heterogeneity was assessed using I2, considering it absent if <25% and high if >75%. A sensitivity analysis was run to explore the impact of the methodological quality on the size of the effect. Mantel-Haenszel's model of random effects was used for the analysis. The primary outcome was to determine the risk of mortality associated with FO and the secondary outcomes were the need for mechanical ventilation (MV), multiple organ dysfunction syndrome (MODS) and length of hospital stay associated with FO.

RESULTS

A total of 9 studies (2312 patients) were included, all of which were observational. Children with FO had a higher mortality than patients without overload (46% vs 26%; OR 5.06; 95% CI 1.77 to 14.48; p<0.01). We found no association between %FO and the risk of MODS (OR: 0.97; 95% CI 0.13 to 7.12; p=0.98). Children with FO required MV more often (83% vs 47%; OR: 4.78; 95% CI 2.51 to 9.11; p<0.01) and had a longer hospital stay (8 days (RIQ 6.5-13.2) vs 7 days (RIQ 6.1-11.5); p<0.01).

CONCLUSION

In children with sepsis, more than 10% FO 24 hours after intensive care admission is associated with higher mortality, the need for MV and length of hospital stay.

The association between hypoalbuminemia and microcirculation, endothelium, and glycocalyx disorders in children with sepsis

OBJECTIVE

The objective of this study was to evaluate the association between serum albumin levels and microcirculation changes, glycocalyx degradation, and the clinical outcomes of interest.

METHODS

Observational, prospective study in children with sepsis. The primary outcome was the association between hypoalbuminemia and microcirculation disorders, endothelial activation and glycocalyx degradation using a perfused boundary region (PBR) (abnormal >2.0 μm on sublingual video microscopy) or plasma biomarkers (syndecan-1, angiopoietin-2).

RESULTS

A total of 125 patients with sepsis were included. The median age was 2.0 years (IQR 0.5-12.5). Children with hypoalbuminemia had more abnormal microcirculation with a higher PBR (2.16 μm [IQR 2.03-2.47] vs. 1.92 [1.76-2.28]; p = .01) and more 4-6 μm capillaries recruited (60% vs. 40%; p = .04). The low albumin group that had the worst PBR had the most 4-6 μm capillaries recruited (rho 0.29; p < .01), 48% higher Ang-2 (p = .04), worse annexin A5 (p = 0.03) and no syndecan-1 abnormalities (p = .21). Children with hypoalbuminemia and a greater percentage of blood volume in their capillaries needed mechanical ventilation more often (56.3% vs. 43.7%; aOR 2.01 95% CI 1.38-3.10: p < .01).

CONCLUSIONS

In children with sepsis, an association was found between hypoalbuminemia and microcirculation changes, vascular permeability, and greater endothelial glycocalyx degradation.

End organ perfusion and pediatric microcirculation assessment

Cardiovascular instability and reduced oxygenation are regular perioperative critical events associated with anesthesia requiring intervention in neonates and young infants. This review article addresses the current modalities of assessing this population's adequate end-organ perfusion in the perioperative period. Assuring adequate tissue oxygenation in critically ill infants is based on parameters that measure acceptable macrocirculatory hemodynamic parameters such as vital signs (mean arterial blood pressure, heart rate, urinary output) and chemical parameters (lactic acidosis, mixed venous oxygen saturation, base deficit). Microcirculation assessment represents a promising candidate for assessing and improving hemodynamic management strategies in perioperative and critically ill populations. Evaluation of the functional state of the microcirculation can parallel improvement in tissue perfusion, a term coined as "hemodynamic coherence". Less information is available to assess microcirculatory disturbances related to higher mortality risk in critically ill adults and pediatric patients with septic shock. Techniques for measuring microcirculation have substantially improved in the past decade and have evolved from methods that are limited in scope, such as velocity-based laser Doppler and near-infrared spectroscopy, to handheld vital microscopy (HVM), also referred to as videomicroscopy. Available technologies to assess microcirculation include sublingual incident dark field (IDF) and sublingual sidestream dark field (SDF) devices. This chapter addresses (1) the physiological basis of microcirculation and its relevance to the neonatal and pediatric populations, (2) the pathophysiology associated with altered microcirculation and endothelium, and (3) the current literature reviewing modalities to detect and quantify the presence of microcirculatory alterations.

Bacterial lipopolysaccharide-induced endothelial activation and dysfunction: a new predictive and therapeutic paradigm for sepsis

BACKGROUND

Lipopolysaccharide, a highly potent endotoxin responsible for severe sepsis, is the major constituent of the outer membrane of gram-negative bacteria. Endothelial cells participate in both innate and adaptive immune responses as the first cell types to detect lipopolysaccharide or other foreign debris in the bloodstream. Endothelial cells are able to recognize the presence of LPS and recruit specific adaptor proteins to the membrane domains of TLR4, thereby initiating an intracellular signaling cascade. However, lipopolysaccharide binding to endothelial cells induces endothelial activation and even damage, manifested by the expression of proinflammatory cytokines and adhesion molecules that lead to sepsis.

MAIN FINDINGS

LPS is involved in both local and systemic inflammation, activating both innate and adaptive immunity. Translocation of lipopolysaccharide into the circulation causes endotoxemia. Endothelial dysfunction, including exaggerated inflammation, coagulopathy and vascular leakage, may play a central role in the dysregulated host response and pathogenesis of sepsis. By discussing the many strategies used to treat sepsis, this review attempts to provide an overview of how lipopolysaccharide induces the ever more complex syndrome of sepsis and the potential for the development of novel sepsis therapeutics.

CONCLUSIONS

To reduce patient morbidity and mortality, preservation of endothelial function would be central to the management of sepsis.

How Do Minerals, Vitamins, and Intestinal Microbiota Affect the Development and Progression of Heart Disease in Adult and Pediatric Patients?

Cardiovascular diseases (CVDs) are the leading cause of death worldwide, far ahead of cancer. Epidemiological data emphasize the participation of many risk factors that increase the incidence of CVDs, including genetic factors, age, and sex, but also lifestyle, mainly nutritional irregularities and, connected with them, overweight and obesity, as well as metabolic diseases. Despite the importance of cardiovascular problems in the whole society, the principles of prevention of CVDs are not widely disseminated, especially among the youngest. As a result, nutritional neglect, growing from childhood and adolescence, translates into the occurrence of numerous disease entities, including CVDs, in adult life. This review aimed to draw attention to the role of selected minerals and vitamins in health and the development and progression of CVDs in adults and children. Particular attention was paid to the effects of deficiency and toxicity of the analyzed compounds in the context of the cardiovascular system and to the role of intestinal microorganisms, which by interacting with nutrients, may contribute to the development of cardiovascular disorders. We hope this article will draw the attention of society and the medical community to emphasize promoting healthy eating and proper eating habits in children and adults, translating into increased awareness and a reduced risk of CVD.

Endothelial dysfunction triggers acute respiratory distress syndrome in patients with sepsis: a narrative review

Acute respiratory distress syndrome (ARDS) is a severe organ failure occurring mainly in critically ill patients as a result of different types of insults such as sepsis, trauma or aspiration. Sepsis is the main cause of ARDS, and it contributes to a high mortality and resources consumption both in hospital setting and in the community. ARDS develops mainly an acute respiratory failure with severe and often refractory hypoxemia. ARDS also has long term implications and sequelae. Endothelial damage plays an important role in the pathogenesis of ARDS. Understanding the mechanisms of ARDS presents opportunities for novel diagnostic and therapeutic targets. Biochemical signals can be used in concert to identify and classify patients into ARDS phenotypes allowing earlier effective treatment with personalised therapies. This is a narrative review where we aimed to flesh out the pathogenetic mechanisms and heterogeneity of ARDS. We examine the links between endothelium damage and its contribution to organ failure. We have also investigated future strategies for treatment with a special emphasis in endothelial damage.

Endothelial and Glycocalyx Biomarkers in Children With Sepsis After One Bolus of Unbalanced or Balanced Crystalloids

OBJECTIVES

To assess the disruption of endothelial glycocalyx integrity in children with sepsis receiving fluid resuscitation with either balanced or unbalanced crystalloids. The primary outcome was endothelial glycocalyx disruption (using perfused boundary region >2 µm on sublingual video microscopy and syndecan-1 greater than 80 mg/dL) according to the type of crystalloid. The secondary outcomes were increased vascular permeability (using angiopoietin-2 level), apoptosis (using annexin A5 level), and associated clinical changes.

DESIGN

A single-center prospective cohort study from January to December 2021.

SETTING

Twelve medical-surgical PICU beds at a university hospital.

PATIENTS

Children with sepsis/septic shock before and after receiving fluid resuscitation with crystalloids for hemodynamic instability.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

We included 106 patients (3.9 yr [interquartile range, 0.60-13.10 yr]); 58 of 106 (55%) received boluses of unbalanced crystalloid. This group had greater odds of endothelial glycocalyx degradation (84.5% vs 60.4%; adjusted odds ratio, 3.78; 95% CI, 1.49-9.58; p < 0.01) 6 hours after fluid administration, which correlated with increased angiopoietin-2 (rho = 0.4; p < 0.05) and elevated annexin A5 ( p = 0.04). This group also had greater odds of metabolic acidosis associated with elevated syndecan-1 (odds ratio [OR], 4.88; 95% CI, 1.23-28.08) and acute kidney injury (OR, 1.7; 95% CI, 1.12-3.18) associated with endothelial glycocalyx damage. The perfused boundary region returned to baseline 24 hours after receiving the crystalloid boluses.

CONCLUSIONS

Children with sepsis, particularly those who receive unbalanced crystalloid solutions during resuscitation, show loss and worsening of endothelial glycocalyx. The abnormality peaks at around 6 hours after fluid administration and is associated with greater odds of metabolic acidosis and acute kidney injury.

The Endothelial Glycocalyx and Neonatal Sepsis

Sepsis carries a substantial risk of morbidity and mortality in newborns, especially preterm-born neonates. Endothelial glycocalyx (eGC) is a carbohydrate-rich layer lining the vascular endothelium, with important vascular barrier function and cell adhesion properties, serving also as a mechano-sensor for blood flow. eGC shedding is recognized as a fundamental pathophysiological process generating microvascular dysfunction, which in turn contributes to multiple organ failure and death in sepsis. Although the disruption of eGC and its consequences have been investigated intensively in the adult population, its composition, development, and potential mechanisms of action are still poorly studied during the neonatal period, and more specifically, in neonatal sepsis. Further knowledge on this topic may provide a better understanding of the molecular mechanisms that guide the sepsis pathology during the neonatal period, and would increase the usefulness of endothelial glycocalyx dysfunction as a diagnostic and prognostic biomarker. We reviewed several components of the eGC that help to deeply understand the mechanisms involved in the eGC disruption during the neonatal period. In addition, we evaluated the potential of eGC components as biomarkers and future targets to develop therapeutic strategies for neonatal sepsis.

The Role of IGL-2 Preservation Solution on Rat Livers during SCS and HOPE

The scarcity of livers for transplantation is rising, and new strategies to extend the donor pool are being explored. One solution is to use marginal grafts from extended criteria donors, presenting, for example, liver steatosis. As current preservation solutions (UW, HTK, and IGL-1) were mainly designed for static cold storage (SCS) only, IGL-2, a modified version of IGL-1, was developed to be suitable for SCS and dynamic preservation, such as hypothermic oxygenated perfusion (HOPE). In this study, we investigated the combined effect of IGL-2, SCS, and HOPE and compared it to the most used preservation solution (UW and Belzer MPS). Four experimental groups with six rats each were designed using Zucker rats. All groups underwent 24 h of SCS (in IGL-2 or UW) + 2 h of normothermic machine perfusion (NMP) at 37 °C to mimic transplantation. HOPE (IGL-2 or Belzer MPS) was performed before NMP on half of the rats. The IGL-2 group demonstrated lower transaminases and a significantly low level of glycocalyx proteins, CASP3, and HMGB1 in the perfusates. These data suggest the protective role of IGL-2 for fatty livers in preserving the endothelial glycocalyx, apoptosis, and inflammation.

Vascular Endothelial Glycocalyx Damage and Potential Targeted Therapy in COVID-19

COVID-19 is a highly infectious respiratory disease caused by a new coronavirus known as SARS-CoV-2. COVID-19 is characterized by progressive respiratory failure resulting from diffuse alveolar damage, inflammatory infiltrates, endotheliitis, and pulmonary and systemic coagulopathy forming obstructive microthrombi with multi-organ dysfunction, indicating that endothelial cells (ECs) play a central role in the pathogenesis of COVID-19. The glycocalyx is defined as a complex gel-like layer of glycosylated lipid–protein mixtures, which surrounds all living cells and acts as a buffer between the cell and the extracellular matrix. The endothelial glycocalyx layer (EGL) plays an important role in vascular homeostasis via regulating vascular permeability, cell adhesion, mechanosensing for hemodynamic shear stresses, and antithrombotic and anti-inflammatory functions. Here, we review the new findings that described EGL damage in ARDS, coagulopathy, and the multisystem inflammatory disease associated with COVID-19. Mechanistically, the inflammatory mediators, reactive oxygen species (ROS), matrix metalloproteases (MMPs), the glycocalyx fragments, and the viral proteins may contribute to endothelial glycocalyx damage in COVID-19. In addition, the potential therapeutic strategies targeting the EGL for the treatment of severe COVID-19 are summarized and discussed.

Biomarkers of Glycocalyx Injury and Endothelial Activation are Associated with Clinical Outcomes in Patients with Sepsis: A Systematic Review and Meta-Analysis

OBJECTIVE

Sepsis is one of the main causes of morbidity and mortality worldwide. Microcirculatory impairment, especially damage to the endothelium and glycocalyx, is often not assessed. The objective of this systematic review and meta-analysis was to summarize the available evidence of the risk of unsatisfactory outcomes in patients with sepsis and elevated glycocalyx injury and endothelial activation biomarkers.

DESIGN

A systematic search was carried out on PubMed/MEDLINE, Embase, Cochrane and Google Scholar up to December 31, 2021, including studies in adults and children with sepsis which measured glycocalyx injury and endothelial activation biomarkers within 48 hours of hospital admission. The primary outcome was the risk of mortality from all causes and the secondary outcomes were the risk of developing respiratory failure (RF) and multiple organ dysfunction syndrome (MODS) in patients with elevations of these biomarkers.

MEASUREMENTS AND MAIN RESULTS

A total of 17 studies (3,529 patients) were included: 11 evaluated syndecan-1 (n=2,397) and 6 endocan (n=1,132). Syndecan-1 was higher in the group of patients who died than in those who survived [255 ng/mL (IQR: 139-305) vs. 83 ng/mL (IQR:40-111); p=0.014]. Patients with elevated syndecan-1 had a greater risk of death (OR 2.32; 95% CI 1.89, 3.10: p<0.001), MODS (OR 3.3; 95% CI 1.51, 7.25: p=0.003;), or RF (OR 7.53; 95% CI 1.86-30.45: p=0.005). Endocan was higher in patients who died [3.1 ng/mL (IQR 2.3, 3.7) vs. 1.62 ng/mL (IQR 1.2, 5.7); OR 9.53; 95% CI 3.34, 27.3; p<0.001], who had MODS (OR 8.33; 95% CI 2.07, 33.58; p=0.003) and who had RF (OR 9.66; 95% CI 2.26, 43.95; p=0.002).

CONCLUSION

Patients with sepsis and abnormal glycocalyx injury and endothelial activation biomarkers have a greater risk of developing respiratory failure, multiple organ failure, and death. Microcirculatory impairment should be routinely evaluated in patients with sepsis, using biomarkers to stratify risk groups.

Case Report: Tachycardia, Hypoxemia and Shock in a Severely Burned Pediatric Patient

Background

Severely burned children are at high risk of secondary intraabdominal hypertension and abdominal compartment syndrome (ACS). ACS is a life-threatening condition with high mortality and requires an effective, minimally invasive treatment to improve the prognosis when the condition is refractory to conventional therapy.

Case presentation

A 4.5-year-old girl was admitted to our hospital 30 h after a severe burn injury. Her symptoms of burn shock were relieved after fluid resuscitation. However, her bloating was aggravated, and ACS developed on Day 5, manifesting as tachycardia, hypoxemia, shock, and oliguria. Invasive mechanical ventilation, vasopressors, and percutaneous catheter drainage were applied in addition to medical treatments (such as gastrointestinal decompression, diuresis, sedation, and neuromuscular blockade). These treatments did not improve the patient's condition until she received continuous renal replacement therapy. Subsequently, her vital signs and laboratory data improved, which were accompanied by decreased intra-abdominal pressure, and she was discharged after nutrition support, antibiotic therapy, and skin grafting.

Conclusion

ACS can occur in severely burned children, leading to rapid deterioration of cardiopulmonary function. Patients who fail to respond to conventional medical management should be considered for continuous renal replacement therapy.

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.

Visualising the endothelial glycocalyx in dogs

The endothelial glycocalyx (eGlx) lines the luminal surface of endothelial cells. It is critical in maintaining vascular health and when damaged contributes to many diseases. Its fragility makes studying the eGlx technically challenging. The current reference standard for eGlx visualisation, by electron microscopy using glutaraldehyde/Alcian blue perfusion fixation, has not been previously reported in dogs. Established techniques were applied to achieve visualisation of the eGlx in the microvasculature of reproductive tissue in five healthy dogs undergoing elective neutering. Uterine and testicular artery samples underwent perfusion fixation, in the presence of Alcian blue, prior to transmission electron microscopy imaging. Image processing software was used to determine eGlx depth. EGlx was visualised in the arteries of two dogs, one testicular and one uterine, with median (range) eGlx depths of 68.2 nm (32.1–122.9 nm) and 47.6 nm (26.1–129.4 nm) respectively. Study of the eGlx is technically challenging, particularly its direct visualisation in clinical samples. Further research is needed to develop more clinically applicable techniques to measure eGlx health.

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Canine glycocalyx has not previously been visualised using the reference technique.

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The endothelial glycocalyx was visualised in dog uterine and testicular arteries.

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Direct visualisation of the endothelial glycocalyx was technically challenging.

Direct Thrombin Inhibitor Dabigatran Compromises Pulmonary Endothelial Integrity in a Murine Model of Breast Cancer Metastasis to the Lungs; the Role of Platelets and Inflammation-Associated Haemostasis

Activation of the coagulation cascade favours metastatic spread, but antithrombotic therapy might also have detrimental effects on cancer progression. In this study, we characterized the effects of dabigatran, a direct reversible thrombin inhibitor, on the pulmonary endothelial barrier and metastatic spread in a murine model of breast cancer metastasis. Dabigatran etexilate (100 mg kg−1) was administered to mice twice daily by oral gavage. Pulmonary metastasis, pulmonary endothelium permeability in vivo, and platelet reactivity were evaluated after intravenous injection of 4T1 breast cancer cells into BALB/c mice. The effect of dabigatran on platelet-dependent protection of pulmonary endothelial barrier in the presence of an inflammatory stimulus was also verified in vitro using human lung microvascular endothelial cell (HLMVEC) cultures. Dabigatran-treated mice harbored more metastases in their lungs and displayed increased pulmonary endothelium permeability after cancer cell injection. It was not associated with altered lung fibrin deposition, changes in INFγ, or complement activation. In the in vitro model of the pulmonary endothelial barrier, dabigatran inhibited platelet-mediated protection of pulmonary endothelium. In a murine model of breast cancer metastasis, dabigatran treatment promoted pulmonary metastasis by the inhibition of platelet-dependent protection of pulmonary endothelial barrier integrity.

Endothelial Damage in Sepsis: The Importance of Systems Biology

The early diagnosis and appropriate stratification of sepsis continues to be one of the most important challenges in modern medicine. Single isolated biomarkers have not been enough to improve diagnostic and prognostic strategies and to progress toward therapeutic goals. The information generated by the human genome project has allowed a more holistic approach to the problem. The integration of genomics, transcriptomics, proteomics and metabolomics in sepsis has allowed us to progress in the knowledge of new pathways which are pathophysiologically involved in this disease. Thus, we have understood the importance of and complex interaction between the inflammatory response and the endothelium. Understanding the role of important parts of the microcirculation, such as the endothelial glycocalyx and its interaction with the inflammatory response, has provided early recognition elements for clinical practice that allow the rational use of traditional medical interventions in sepsis. This comprehensive approach, which differs from the classical mechanistic approach, uses systems biology to increase the diagnostic and prognostic spectrum of endothelial damage biomarkers in sepsis, and to provide information on new pathways involved in the pathophysiology of the disease. This, in turn, provides tools for perfecting traditional medical interventions, using them at the appropriate times according to the disease's pathophysiological context, while at the same time discovering new and improved therapeutic alternatives. We have the challenge of transferring this ideal scenario to our daily clinical practice to improve our patients' care. The purpose of this article is to provide a general description of the importance of systems biology in integrating the complex interaction between the endothelium and the inflammatory response in sepsis.

Protection and rebuilding of the endothelial glycocalyx in sepsis - Science or fiction?

The endothelial glycocalyx (eGC), a delicate carbohydrate-rich structure lining the luminal surface of the vascular endothelium, is vital for maintenance of microvascular homeostasis. In sepsis, damage of the eGC triggers the development of vascular hyperpermeability with consecutive edema formation and organ failure. While there is evidence that protection or rebuilding of the eGC might counteract sepsis-induced vascular leakage and improve outcome, approved therapeutics are not yet available. This narrative review aims to outline possible therapeutic strategies to ameliorate organ dysfunction caused by eGC impairment.

Endothelial dysfunction: a therapeutic target in bacterial sepsis?

INTRODUCTION

Endothelial cells maintain vascular integrity, tone, and patency and have important roles in hemostasis and inflammatory responses. Although some degree of endothelial dysfunction with increased vascular permeability may be necessary to control local infection, excessive dysfunction plays a central role in the pathogenesis of sepsis-related organ dysfunction and failure as it results in dysregulated inflammation, vascular leakage, and abnormal coagulation. The vascular endothelium has thus been proposed as a potential target for therapeutic intervention in patients with sepsis.

AREAS COVERED

Different mechanisms underlying sepsis-related dysfunction of the vascular endothelium are discussed, including glycocalyx shedding, nitrosative stress, and coagulation factors. Potential therapeutic implications of each mechanism are mentioned.

EXPERT OPINION

Multiple targets to protect or restore endothelial function have been suggested, but endothelium-driven treatments remain a future potential at present. As some endothelial dysfunction and permeability may be necessary to remove infection and repair damaged tissue, targeting the endothelium may be a particular challenge. Ideally, therapies should be guided by biomarkers related to that specific pathway to ensure they are given only to patients most likely to respond. This enrichment based on biological plausibility and theragnostics will increase the likelihood of a beneficial response in individual patients and enable more personalized treatment.

Time-Dependent Dynamics Required for the Degradation and Restoration of the Vascular Endothelial Glycocalyx Layer in Lipopolysaccharide-Treated Septic Mice

The endothelial glycocalyx (GCX) plays a key role in the development of organ failure following sepsis. Researchers have investigated GCX degradation caused by pathological conditions. Nonetheless, the GCX restoration process remains poorly understood. Herein, we developed a model in which GCX restoration could be reproduced in mice using in vivo imaging and a dorsal skinfold chamber (DSC). The severity of sepsis was controlled by adjusting the dose of lipopolysaccharide (LPS) used to trigger GCX degradation in BALB/c mice. We evaluated the GCX thickness, leukocyte-endothelial interactions, and vascular permeability using in vivo imaging through DSC under intravital microscopy. The plasma concentration of syndecan-1(Sdc-1), a GCX structural component, was also determined as a marker of GCX degradation. Thus, we developed a reproducible spontaneous GCX recovery model in mice. Degraded GCX was restored within 24 h by the direct visualization of the endothelial GCX thickness, and leukocyte-endothelial interactions. In contrast, indirectly related indicators of recovery from sepsis, such as body weight and blood pressure, required a longer recovery time. This model can be used to study intractable angiopathy following sepsis.

Glycocalyx Impairment in Vascular Disease: Focus on Inflammation

The glycocalyx is a complex polysaccharide-protein layer lining the lumen of vascular endothelial cells. Changes in the structure and function of the glycocalyx promote an inflammatory response in blood vessels and play an important role in the pathogenesis of many vascular diseases (e.g., diabetes, atherosclerosis, and sepsis). Vascular endothelial dysfunction is a hallmark of inflammation-related diseases. Endothelial dysfunction can lead to tissue swelling, chronic inflammation, and thrombosis. Therefore, elimination of endothelial inflammation could be a potential target for the treatment of vascular diseases. This review summarizes the key role of the glycocalyx in the inflammatory process and the possible mechanism by which it alleviates this process by interrupting the cycle of endothelial dysfunction and inflammation. Especially, we highlight the roles of different components of the glycocalyx in modulating the inflammatory process, including components that regulate leukocyte rolling, L-selectin binding, inflammasome activation and the signaling interactions between the glycocalyx components and the vascular cells. We discuss how the glycocalyx interferes with the development of inflammation and the importance of preventing glycocalyx impairment. Finally, drawing on current understanding of the role of the glycocalyx in inflammation, we consider a potential strategy for the treatment of vascular diseases.

Optimizing Fluid Resuscitation and Preventing Fluid Overload in Patients with Septic Shock

Intravenous fluid administration remains an important component in the care of patients with septic shock. A common error in the treatment of septic shock is the use of excessive fluid in an effort to overcome both hypovolemia and vasoplegia. While fluids are necessary to help correct the intravascular depletion, vasopressors should be concomitantly administered to address vasoplegia. Excessive fluid administration is associated with worse outcomes in septic shock, so great care should be taken when deciding how much fluid to give these vulnerable patients. Simple or strict "recipes" which mandate an exact amount of fluid to administer, even when weight based, are not associated with better outcomes and therefore should be avoided. Determining the correct amount of fluid requires the clinician to repeatedly assess and consider multiple variables, including the fluid deficit, organ dysfunction, tolerance of additional fluid, and overall trajectory of the shock state. Dynamic indices, often involving the interaction between the cardiovascular and respiratory systems, appear to be superior to traditional static indices such as central venous pressure for assessing fluid responsiveness. Point-of-care ultrasound offers the bedside clinician a multitude of applications which are useful in determining fluid administration in septic shock. In summary, prevention of fluid overload in septic shock patients is extremely important, and requires the careful attention of the entire critical care team.

Association Between Unbalanced Solutions and Acute Kidney Injury During Fluid Resuscitation in Children With Sepsis

OBJECTIVE

To evaluate the outcomes of patients with sepsis-associated organ dysfunction and septic shock who receive fluid resuscitation with balanced and unbalanced solutions in a middle-income country.

DESIGN

An observational, analytical cohort study with propensity score matching (PSM) in children admitted to a pediatric intensive care unit (PICU). Patients from one month to 17 years old who required fluid boluses due to hemodynamic instability were included. The primary outcome was the presence of acute kidney injury and the secondary outcomes were the need to begin continuous renal replacement therapy (CRRT), metabolic acidosis, PICU length of stay and mortality.

MEASUREMENTS AND MAIN RESULTS

Out of the 1,074 admissions to the PICU during the study period, 99 patients had sepsis-associated organ dysfunction and septic shock. Propensity score matching was performed including each patient´s baseline characteristics. The median age was 9.9 months (IQR 4.9-22.2) with 55.5% of the patients being male. Acute kidney injury was seen less frequently in children who received a balanced solution than in those who received an unbalanced solution (20.3% vs 25.7% P = 0.006 ORa, 0.75; 95% CI, 0.65-0.87), adjusted for disease severity. In addition, the group that received balanced solutions had less need for CRRT (3.3 % vs 6.5%; P = 0.02 ORa 0.48; 95% CI, 0.36-0.64) and a shorter PICU stay (6 days IQR 4.4-20.2 vs 10.2 days IQR 4.7-26; P < 0.001) than the group with unbalanced solutions. We found no difference in the frequency of metabolic acidosis (P = 0.37), hyperchloremia (P = 0.11) and mortality (P = 0.25) between the 2 groups.

CONCLUSION

In children with sepsis-associated organ dysfunction and septic shock, the use of unbalanced solutions for fluid resuscitation is associated with a higher frequency of acute kidney injury, a greater need for continuous renal support and a longer PICU stay compared to the use of balanced solutions, in a middle-income country.

Paediatric inflammatory multisystem syndrome temporally associated with COVID-19 (PIMS-TS): a narrative review and the viewpoint of the Latin American Society of Pediatric Intensive Care (SLACIP) Sepsis Committee

Background

In this review, we discuss some important aspects of paediatric inflammatory multisystem syndrome temporally associated with COVID-19 (PIMS-TS), a new syndrome that is temporally related to previous exposure to SARS-CoV-2 infection. This virus has a broad spectrum of presentation that may overlap with Kawasaki disease in terms of presenting symptoms and laboratory and cardiac findings. Our objective was to review and summarise published evidence regarding the most important aspects of PIMS-TS, with special emphasis on the treatment strategies suggested for middle-income and low-income countries.

Methods

A systematic review of the literature was performed in the principal medical databases including PubMed, Embase (OVID) and Google Scholar between December 2019 and August 2020.

Results

A total of 69 articles were identified in the described databases. Altogether, 13 articles met the inclusion criteria and were eligible. The most frequently described symptoms of PIMS-TS include fever (82%), shock (67%) and gastrointestinal (87%), skin (71%) and cardiac disorders (75%). In most series, it has been observed between 4 and 6 weeks after the pandemic appears in the general population. Multisystem inflammatory syndrome in children is presented as a great systemic inflammatory response syndrome, which sometimes presents as shock requiring fluid resuscitation and vasoactive drug support (26%). Several treatment strategies have been used, including immunoglobulin, steroids, aspirin, anakinra and anticoagulation among others. These general and specific interventions should be guided by an interdisciplinary and multidisciplinary team, especially in settings with limited resources.

Conclusions

PIMS-TS COVID-19 is a new type of presentation of SARS-CoV-2 infection, with an exaggerated inflammatory response and frequent-but not exclusive-digestive and myocardial involvement. It is important to describe the clinical course and outcomes in countries with limited resources as well as establish the role of biomarkers for early diagnosis, effective therapeutic strategies and outpatient follow-up schemes.

The glycocalyx: a central regulator of vascular function

The endothelial glycocalyx is a specialized extracellular matrix that covers the apical side of vascular endothelial cells, projecting into the lumen of blood vessels. The composition of the glycocalyx has been studied in great detail, and it is known to be composed of a mixture of proteoglycans, glycosaminoglycans, and glycoproteins. Although this structure was once believed to be a passive physical barrier, it is now recognized as a multifunctional and dynamic structure that participates in many vascular processes, including but not limited to vascular permeability, inflammation, thrombosis, mechanotransduction, and cytokine signaling. Because of its participation in many physiological and pathophysiological states, comprehensive knowledge of the glycocalyx will aid future vascular biologists in their research. With that in mind, this review discusses the biochemical structure of the glycocalyx and its function in many vascular physiological processes. We also briefly review a more recent discovery in glycocalyx biology, the placental glycocalyx.

Case Report: Endothelial Glycocalyx Damage in Critically ill Patients With SARS-CoV-2-Related Multisystem Inflammatory Syndrome (MIS-C)

Endothelial insult and damage is one of the reported consequences of SARS-CoV-2 infection. It has been associated with severe inflammation, thrombotic phenomena and profound hypoxemia in critically ill patients. Endothelial activation leads to a loss of the endothelium's antithrombotic properties which, under normal conditions, are maintained by the endothelial glycocalyx, a carbohydrate-rich layer that covers the luminal surface of endothelial cells. In children, one of the serious forms of SARS-CoV-2 virus disease (COVID-19) is multisystem inflammatory syndrome (MIS-C). This new disease is characterized by a large inflammatory response and frequent cardiovascular, cutaneous and gastrointestinal disorders. We describe the first two cases of critically ill children with MIS-C who evidenced a large inflammatory response associated with elevated plasma and imaging biomarkers of endothelial activation and endothelial glycocalyx degradation. This microcirculation involvement in MIS-C could, at least partially, explain some of the clinical manifestations and laboratory and imaging alterations found in these patients. These findings contribute to a better understanding of this disease and suggest that medications to modulate the inflammatory response and protect or restore the endothelial glycocalyx should be considered in future studies.

Vitamin C and Cardiovascular Disease: An Update

The potential beneficial effects of the antioxidant properties of vitamin C have been investigated in a number of pathological conditions. In this review, we assess both clinical and preclinical studies evaluating the role of vitamin C in cardiac and vascular disorders, including coronary heart disease, heart failure, hypertension, and cerebrovascular diseases. Pitfalls and controversies in investigations on vitamin C and cardiovascular disorders are also discussed.

Targeting of G-protein coupled receptors in sepsis

The Third International Consensus Definitions (Sepsis-3) define sepsis as life-threatening multi-organ dysfunction caused by a dysregulated host response to infection. Sepsis can progress to septic shock-an even more lethal condition associated with profound circulatory, cellular and metabolic abnormalities. Septic shock remains a leading cause of death in intensive care units and carries a mortality of almost 25%. Despite significant advances in our understanding of the pathobiology of sepsis, therapeutic interventions have not translated into tangible differences in the overall outcome for patients. Clinical trials of antagonists of various pro-inflammatory mediators in sepsis have been largely unsuccessful in the past. Given the diverse physiologic roles played by G-protein coupled receptors (GPCR), modulation of GPCR signaling for the treatment of sepsis has also been explored. Traditional pharmacologic approaches have mainly focused on ligands targeting the extracellular domains of GPCR. However, novel techniques aimed at modulating GPCR intracellularly through aptamers, pepducins and intrabodies have opened a fresh avenue of therapeutic possibilities. In this review, we summarize the diverse roles played by various subfamilies of GPCR in the pathogenesis of sepsis and identify potential targets for pharmacotherapy through these novel approaches.

Childhood Obesity, Endothelial Cell Activation, and Critical Illness

Pediatric obesity is increasing in prevalence and is frequently an antecedent to adult obesity and adult obesity-associated morbidities such as atherosclerosis, type II diabetes, and chronic metabolic syndrome. Endothelial cell activation, one aspect of inflammation, is present in the early stages of atherosclerosis, often prior to the onset of symptoms. Endothelial activation is a pathological condition in which vasoconstricting, pro-thrombotic, and proliferative mediators predominate protective vasodilating, anti-thrombogenic, and anti-mitogenic mediators. Many studies report poor outcomes among obese children with systemic endothelial activation. Likewise, the link between childhood obesity and poor outcomes in critical illness is well-established. However, the link between obesity and severity of endothelial activation specifically in the setting of critical illness is largely unstudied. Although endothelial cell activation is believed to worsen disease in critically ill children, the nature and extent of this response is poorly understood due to the difficulty in measuring endothelial cell dysfunction and destruction. Based on the data available for the obese, asymptomatic population and the obese, critically ill population, the authors posit that obesity, and obesity-associated chronic inflammation, including oxidative stress and insulin resistance, may contribute to endothelial activation and associated worse outcomes among critically ill children. A research agenda to examine this hypothesis is suggested.