The glycocalyx and its significance in human medicine

Endothelial cell metabolism in cardiovascular physiology and disease

Endothelial cells are multifunctional cells that form the inner layer of blood vessels and have a crucial role in vasoreactivity, angiogenesis, immunomodulation, nutrient uptake and coagulation. Endothelial cells have unique metabolism and are metabolically heterogeneous. The microenvironment and metabolism of endothelial cells contribute to endothelial cell heterogeneity and metabolic specialization. Endothelial cell dysfunction is an early event in the development of several cardiovascular diseases and has been shown, at least to some extent, to be driven by metabolic changes preceding the manifestation of clinical symptoms. Diabetes mellitus, hypertension, obesity and chronic kidney disease are all risk factors for cardiovascular disease. Changes in endothelial cell metabolism induced by these cardiometabolic stressors accelerate the accumulation of dysfunctional endothelial cells in tissues and the development of cardiovascular disease. In this Review, we discuss the diversity of metabolic programmes that control endothelial cell function in the cardiovascular system and how these metabolic programmes are perturbed in different cardiovascular diseases in a disease-specific manner. Finally, we discuss the potential and challenges of targeting endothelial cell metabolism for the treatment of cardiovascular diseases.

Comparative electron microscopic visualization of the lung alveolar epithelial glycocalyx with different staining and labeling methods

The alveolar surface of the lung is lined by an epithelium consisting of type I (AECI) and type II alveolar epithelial cells (AECII). This epithelium is covered by a liquid alveolar lining layer (ALL). Besides intra-alveolar surfactant, ALL also contains the alveolar epithelial glycocalyx on the apical side of AECI and AECII. To better understand the alveolar epithelial glycocalyx, its ultrastructural visualization by transmission electron microscopy is required. The aim of this study was to systematically re-evaluate routine cytochemical methods for visualization of the alveolar epithelial glycocalyx and specifically its glycan components. For this purpose, we used chemical fixation by vascular perfusion with aldehydes as a common routine approach in mice. After fixation, staining is needed for glycocalyx visualization. Cytochemical staining agents such as alcian blue, ruthenium red, and lanthanum nitrate were compared. In addition, SNL (Sambucus nigra lectin) and UEA1 (Ulex europaeus agglutinin I) were used for sialic acid and fucose-specific labeling. Alcian blue showed the strongest staining, with cloud-like structures, whereas ruthenium red appeared as thread-like structures. On the other hand, lanthanum nitrate did not stain the alveolar epithelial glycocalyx. For specific sialic acid and fucose labeling, both lectins presented a specific signal. In conclusion, these methods can be used routinely for assessing ultrastructural changes of the alveolar epithelial glycocalyx in experimental in vivo models under different physiological and pathological conditions. In addition, cytochemical staining by tissue massage and post-embedding lectin labeling after vascular perfusion support 3R (reduction, refinement, replacement) principles of animal welfare.

Co-therapy with S1P and heparan sulfate derivatives to restore endothelial glycocalyx and combat pro-atherosclerotic endothelial dysfunction

AIMS

Endothelial cell (EC) glycocalyx (GCX) shedding from disturbed blood flow and chemical factors leads to low-density lipoprotein infiltration, reduced nitric oxide synthesis, vascular dysfunction and atherosclerosis. This study evaluates a therapy combining sphingosine-1-phosphate (S1P) and heparin (heparan sulfate derivative). We hypothesized that heparin/S1P co-treatment repairs mechanically damaged EC GCX in disturbed flow (DF) regions and restores anti-atherosclerotic mechanotransduction to treat cardiovascular disease.

MATERIALS AND METHODS

We used a parallel-plate flow chamber to simulate flow conditions in vitro and a partial carotid ligation mouse model to mimic DF in vivo. Heparin and albumin-bound S1P were administered to assess their reparative effects on the endothelial GCX. Fluorescent staining, confocal microscopy, and ultrasound evaluated endothelial cell function and endothelial-dependent vascular function. Barrier functionality was assessed via macrophage uptake. Heparin/S1P mechanism-of-action insights were gained through fluid dynamics simulations and staining of GCX synthesis enzyme and S1P receptor. Statistical analyses validated the results.

KEY FINDINGS

The in vitro data showed that heparin/S1P therapy improves DF-conditioned ECs by restoring GCX and elevating vasodilator eNOS (endothelial-type nitric oxide synthase) expression. In vivo studies confirmed GCX degradation, vessel inflammation, hyperpermeability, and wall thickening in the mouse model's partially ligated left carotid artery. Heparin/S1P treatment restored GCX thickness and coverage, reduced inflammation and hyperpermeability, and inhibited vessel wall thickening.

SIGNIFICANCE

This work introduces a new approach to regenerating the EC GCX and restoring its function in ECs under DF conditions, offering a groundbreaking solution for preventing cardiovascular diseases like atherosclerosis.

Cellular Signaling at the Nano-Bio Interface: Spotlighting Membrane Curvature

No longer viewed as a passive consequence of cellular activities, membrane curvature-the physical shape of the cell membrane-is now recognized as an active constituent of biological processes. Nanoscale topographies on extracellular matrices or substrate surfaces impart well-defined membrane curvatures on the plasma membrane. This review examines biological events occurring at the nano-bio interface, the physical interface between the cell membrane and surface nanotopography, which activates intracellular signaling by recruiting curvature-sensing proteins. We encompass a wide range of biological processes at the nano-bio interface, including cell adhesion, endocytosis, glycocalyx redistribution, regulation of mechanosensitive ion channels, cell migration, and differentiation. Despite the diversity of processes, we call attention to the critical role of membrane curvature in each process. We particularly highlight studies that elucidate molecular mechanisms involving curvature-sensing proteins with the hope of providing comprehensive insights into this rapidly advancing area of research.

Experimental and clinical perspectives on glycocalyx integrity and its relation to acute respiratory distress syndrome

The development of microcirculation imaging devices has significantly advanced our comprehension of the capillary environment's dynamics. Early research suggested that erythrocytes did not contact the vessel's inner surface due to the Fåhraeus effect, implying the presence of a covering on the endothelial cell surface. Subsequent electron microscopy studies revealed this layer to be a complex part of the vessel wall, now known as the endothelial glycocalyx (EG). The EG is a network of proteoglycans and glycoproteins bound to the endothelial membrane, incorporating soluble molecules from the endothelium and plasma. Over time, studies have elucidated the structure, function, and therapeutic targets of the glycocalyx, underscoring its pivotal role in vascular biology. The presence of cellular extensions of lung tissue cells in both vascular and nonvascular areas demonstrates the pivotal role of the glycocalyx in pulmonary vascular leak, surfactant dysfunction, impaired lung compliance and gas exchange abnormalities, which are hallmarks of acute respiratory distress syndrome (ARDS). It is of the utmost importance to elucidate the mechanisms underlying alveolocapillary glycocalyx degradation to develop efficacious treatments for ARDS, which has a mortality rate of 35 %. An understanding of the glycocalyx's role in vascular integrity provides a foundation for exploring new therapeutic avenues to mitigate lung injury and improve clinical outcomes in ARDS patients.

Evaluation of circulating glypican 4 as a novel biomarker in disease - A comprehensive review

Glypican 4 (GPC4), a member of the cell surface heparan sulfate proteoglycan family, plays a crucial role in regulating various cell signaling and developmental processes. Its ability to be released from the cell surface into the bloodstream through shedding makes it a promising blood-based biomarker in health and disease. In this context, circulating GPC4 has been initially proposed as an insulin-sensitizing adipokine being linked with various conditions of insulin resistance. In addition, serum levels of GPC4 can indicate glycocalyx shedding and associated pathophysiological states, such as systemic inflammation. Particularly in a morbid and elderly population, increased GPC4 concentrations may reflect general organ dysfunction and an advanced state of multimorbidity, showing a strong association with the prognosis of severe conditions such as heart failure or advanced cancer. This comprehensive review is the first to summarize the existing scientific knowledge on the role of circulating GPC4 as a novel diagnostic and prognostic biomarker across different pathologic conditions. We also discuss in detail the putative underlying pathophysiological mechanisms behind these findings.

Flow-sensitive ion channels in vascular endothelial cells: Mechanisms of activation and roles in mechanotransduction

The purpose of this review is to evaluate the current knowledge about the mechanisms by which mechanosensitive ion channels are activated by fluid shear stress in endothelial cells. We focus on three classes of endothelial ion channels that are most well studied for their sensitivity to flow and roles in mechanotransduction: inwardly rectifying K+ channels, Piezo channels, and TRPV channels. We also discuss the mechanisms by which these channels initiate and contribute to mechanosensitive signaling pathways. Three types of mechanisms have been described for flow-induced activation of ion channels: 1) through interaction with apical membrane flow sensors, such as glycocalyx, which is likely to be deformed by flow, 2) directly by sensing membrane stretch that is induced by shear stress, or 3) via flow-sensitive channel-channel or lipid channel interactions. We also demonstrate the physiological role of these channels and how they are related to cardiovascular and neurological diseases. Further studies are needed to determine how these channels function cooperatively to mediate the endothelial response to flow.

Burn-Related Glycocalyx Derangement and the Emerging Role of MMP8 in Syndecan Shedding

Burn injuries often lead to severe complications, including acute respiratory distress syndrome (ARDS), driven in part by systemic inflammation and glycocalyx disruption. In this study, we analyzed the sera of 28 patients after burn trauma and utilized single-cell RNA sequencing (scRNA-seq) along with microarray transcriptomic analysis to decipher the impact of burn injury on glycocalyx derangement. We observed the significant upregulation of immune cell-derived degrading enzymes, particularly matrix metalloproteinase-8 (MMP8), which correlated with increased immune cell infiltration and glycocalyx derangement. Serum analyses of burn patients revealed significantly elevated levels of shed glycocalyx components and MMP8, both correlating with the presence of inhalation injury. Consequently, the treatment of human in vitro lung tissue models with MMP8 induced significant glycocalyx shedding in alveolar epithelial cells. Together, based on these findings, we propose that MMP8 plays a previously unrecognized role in glycocalyx disruption and subsequent lung injury post-burn, which implies that inhibiting MMP8 may represent a promising therapeutic strategy for alleviating lung injury after burn trauma.

Activation of the Voltage-Gated Potassium Channel by Amphiphilic Glycopeptides

Voltage-gated ion channels (VGICs) are allosterically modulated by glycosaminoglycan proteoglycans and sialic acid glycans. However, the structural diversity and heterogeneity of these biomolecules pose significant challenges to precisely delineate their underlying structure-activity relationships. Herein, we demonstrate how heparan sulfate (HS) and sialic acid synthetic glycans appended on amphiphilic glycopeptide backbone influence cell membrane persistence and modulate the gating of the Kv2.1 channel. Utilizing a panel of amphiphilic glycopeptides comprising HS disaccharides and sialic acid trisaccharide glycans, we observed that sulfation of HS and flexible α(2-6) sialylation result in prolonged persistence of glycopeptides on the cell membrane compared to non-sulfated HS and α(2-3) sialylation respective. This variation in glycocalyx composition was associated with a noticeable difference in the effects of these compounds on the activation and deactivation properties of the voltage-gated Kv2.1 channel with our strongest membrane associating compound demonstrating the most potent channel-activation propensity. Our findings demonstrate that sulfation charges on glycopeptide play a critical role in their membrane association propensities and endow them with VGIC activation properties. These results provide a valuable insight into the role of cell surface glycans in VGIC activities.

Evidence that the cell glycocalyx envelops respiratory syncytial virus (RSV) particles that form on the surface of RSV-infected human airway cells

We examined how respiratory syncytial virus (RSV) particles circumvent the overlying glycocalyx on virus-infected A549 cells. The glycocalyx was detected using the lectin WGA-AL488 probe, and the antibodies anti-HS and anti-syndecan-4 that detect heparin sulphate (HS) and the syndecan-4 protein (SYND4) respectively. Imaging of RSV-infected cells provided evidence that the glycocalyx envelopes the virus filaments as they form, and that components of the glycocalyx such as HS moieties and SYND4 are displayed on the surface of the mature virus filaments. Recombinant expression of the G protein in these cells suggested that the G protein was trafficked into pre-existing filamentous cellular structures with a well-defined glycocalyx, further suggesting that the glycocalyx is maintained at the site of virus particle assembly. These data provide evidence that during RSV particle assembly the virus filaments become enveloped by the glycocalyx, and that the glycocalyx should be considered as a structural component of virus filaments.

Syndecan-1 in the Serum of Deceased Kidney Donors as a Potential Biomarker of Kidney Function

BACKGROUND

The process of kidney transplantation remains the optimal treatment for end-stage renal disease, offering improved quality of life and increased survival rates compared to long-term dialysis. However, despite advances in surgical techniques, immunosuppression regimens, and post-operative care, there are still significant challenges in predicting the organ's status and long-term outcomes of transplantation. Among the many factors that influence graft survival, the quality of the donated organ plays a fundamental role. There is an ongoing need for accurate and reliable biomarkers. Syndecan-1 is found in the endothelial glycocalyx and shed at a higher rate into the blood during systemic pathological conditions. The aim of this study is to evaluate the potential of serum syndecan-1 levels as a biomarker for assessing donor kidney quality and to investigate its correlation with donor characteristics and short-term outcomes in kidney recipients.

MATERIAL AND METHODS

We investigated serum syndecan-1 levels in 80 deceased donors and correlated them with donor characteristics and short-term outcomes (defined as delayed graft function - defined as the need for dialysis within the first week post-transplantation and renal function at 3 months post-transplantation - assessed using serum creatinine levels) in 104 corresponding kidney recipients. This single-center retrospective observational cohort study was conducted from April to December 2021.

RESULTS

The donor pool consisted of 65% males with a median age of 53 years. Of these, 45 donors (56%) were classified as extended criteria donors. Higher syndecan-1 levels correlated with the last creatinine levels before organ procurement (R = 0.32, p = 0.01) and were marginally higher in donors with acute kidney injury (p = 0.07). However, syndecan-1 levels were not associated with short-term outcomes in kidney recipients (renal function at 3 months).

CONCLUSIONS

The data suggests syndecan-1 could be a potential biomarker for assessing donor kidney quality, although its implications on recipient outcomes require further study. This pilot investigation underscores the importance of syndecan-1 in evaluating organ quality but highlights the necessity for more extensive research to validate these findings and explore their implications in transplant success.

Analysis of the prognostic efficacy of syndecan-1 for patients with ACLF and its functional role in liver regeneration

BACKGROUND

Acute-on-chronic liver failure (ACLF) is a syndrome characterized by systemic inflammation with a high short-term mortality rate. Syndecan-1 (SDC-1) can independently predict the 90-day mortality of patients with septic shock. However, the role of SDC-1 in ACLF remains unknown.

METHODS

In this study, serum SDC-1 levels were examined in 2 cohorts, which included 174 ACLF patients. And a mouse ACLF model induced by tetrachloride, lipopolysaccharide, and D-galactosamine was established, to evaluate the effects of sulodexide and heparan sulfate (side chains of SDC-1) on ACLF in vivo.

RESULTS

Baseline serum SDC-1 levels in 101 ACLF patients (847.72, 499.79-1511.37 ng/ml) were significantly higher than in healthy controls (33.58, 27.08-43.34 ng/ml) (P < 0.0001). The baseline SDC-1 levels of patients who died or accepted a liver transplantation within 90 days were markedly higher than those of patients who survived (P < 0.05). A novel prognostic model (UIAS) based on upper gastrointestinal bleeding, INR, age, and SDC-1 was developed. The AUROC of the UIAS score for 28-day deterioration in ACLF patients was 0.884, indicating an obviously greater predictive performance for the outcomes of ACLF than those of the Child-Pugh (AUROC = 0.646), MELD (AUROC = 0.713), and COSSH-ACLF II scores (AUROC = 0.713). Moreover, we found that heparan sulfate and sulodexide could increase the expression of SDC-1 and attenuate liver injury, by promoting liver regeneration and inhibiting cell apoptosis through the activation of JAK1/STAT3 signalling.

CONCLUSIONS

Collectively, our findings suggest that SDC-1 represents a potential prognostic and therapeutic target for ACLF and should be further investigated.

Repetitive Low-Level Blast Exposure Alters Circulating Myeloperoxidase, Matrix Metalloproteinases, and Neurovascular Endothelial Molecules in Experienced Military Breachers

Repeated exposure to low-level blast overpressure, frequently experienced during explosive breaching and heavy weapons use in training and operations, is increasingly recognised as a serious risk to the neurological health of military personnel. Although research on the underlying pathobiological mechanisms in humans remains limited, this study investigated the effects of such exposure on circulating molecular biomarkers associated with inflammation, neurovascular damage, and endothelial injury. Blood samples from military breachers were analysed for myeloperoxidase (MPO), matrix metalloproteinases (MMPs), and junctional proteins indicative of blood-brain barrier (BBB) disruption and endothelial damage, including occludin (OCLN), zonula occludens-1 (ZO-1), aquaporin-4 (AQP4), and syndecan-1 (SD-1). The results revealed significantly elevated levels of MPO, MMP-3, MMP-9, and MMP-10 in breachers compared to unexposed controls, suggesting heightened inflammation, oxidative stress, and vascular injury. Increased levels of OCLN and SD-1 further indicated BBB disruption and endothelial glycocalyx degradation in breachers. These findings highlight the potential for chronic neurovascular unit damage/dysfunction from repeated blast exposure and underscore the importance of early targeted interventions-such as reducing oxidative stress, reinforcing BBB integrity, and managing inflammation-that could be essential in mitigating the risk of long-term neurological impairment associated with blast exposure.

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.

Cadmium promotes hyaluronan synthesis by inducing hyaluronan synthase 3 expression in cultured vascular endothelial cells via the c-Jun N-terminal kinase-c-Jun pathway

Cadmium is a heavy metal risk factor for various cardiovascular diseases, such as atherosclerosis. In atherosclerotic lesions, hyaluronan, a glycosaminoglycan consisting of β4-glucuronic acid-β3-N-acetylglucosamine disaccharides repeats, is highly accumulated, regulating signal transduction, cell migration, and angiogenesis. Hyaluronan is synthesized by hyaluronan synthase (HAS)1-3 in the plasma membrane and secreted into the extracellular space. Hyaluronan derived from HAS3 promotes inflammatory responses. Recently, we found that cadmium elongates chondroitin/dermatan sulfate chains in vascular endothelial cells and that glycosaminoglycan sugar chains are potential targets for the vascular toxicity of cadmium. Therefore, hyaluronan, a glycosaminoglycan sugar chain, may also affected by cadmium; however, this has not yet been clarified. In this study, we aimed to analyze the effect of cadmium on hyaluronan synthesis using cultured aortic endothelial cells. Cadmium at a concentration of 2 µM upregulated hyaluronan synthesis in the medium and specifically induced HAS3 mRNA and protein expression. However, cadmium-mediated HAS3 induction was abolished by the inhibition of the c-Jun N-terminal kinase (JNK)-c-Jun pathway. Moreover, JNK inhibition prevented the increase in hyaluronan levels in the medium. These results revealed that the JNK-c-Jun pathway was involved in HAS3-mediated hyaluronan synthesis by cadmium in vascular endothelial cells, suggesting that endothelial HAS3 induction contributes to atherosclerotic lesion formation by promoting inflammatory responses.

Vascular endothelial cell injury: causes, molecular mechanisms, and treatments

Vascular endothelial cells form a single layer of flat cells that line the inner surface of blood vessels, extending from large vessels to the microvasculature of various organs. These cells are crucial metabolic and endocrine components of the body, playing vital roles in maintaining circulatory stability, regulating vascular tone, and preventing coagulation and thrombosis. Endothelial cell injury is regarded as a pivotal initiating factor in the pathogenesis of various diseases, triggered by multiple factors, including infection, inflammation, and hemodynamic changes, which significantly compromise vascular integrity and function. This review examines the causes, underlying molecular mechanisms, and potential therapeutic approaches for endothelial cell injury, focusing specifically on endothelial damage in cardiac ischemia/reperfusion (I/R) injury, sepsis, and diabetes. It delves into the intricate signaling pathways involved in endothelial cell injury, emphasizing the roles of oxidative stress, mitochondrial dysfunction, inflammatory mediators, and barrier damage. Current treatment strategies-ranging from pharmacological interventions to regenerative approaches and lifestyle modifications-face ongoing challenges and limitations. Overall, this review highlights the importance of understanding endothelial cell injury within the context of various diseases and the necessity for innovative therapeutic methods to improve patient outcomes.

Correlation of Hyaluronic Acid (HA), Syndecan-1 (SDC-1), Heparan Sulfate (HS) With Early Stage End Organ Dysfunction in Sepsis Patients

ABSTRACT

The aim of this study was to explore the relationship between the changes in early degradation products of polysaccharide coatings [such as hyaluronic acid (HA), syndecan-1 (SDC-1), and heparan sulfate (HS)] and the development of organ dysfunction in sepsis patients. We conducted a retrospective analysis on 140 sepsis patients admitted from January 2021 to June 2022, who formed the study group; 100 healthy individuals who underwent health checks during the same period were included as the control group. The study found that the expression levels of HA, SDC-1, and HS on admission and within 24 hours of admission in sepsis patients, as well as the early change rates, were positively correlated with organ dysfunction ( P < 0.05). Through receiver operating characteristic curve analysis, we discovered that the early change rates of HA, SDC-1, and HS have high predictive value for organ dysfunction in sepsis patients, with the combined predictive value being the most significant. The study conclusion points out that the increased levels of HA, SDC-1, HS, and other degradation products of polysaccharide coatings in the early stage of sepsis are positively associated with the occurrence of organ dysfunction. Clinicians can use the early expression changes of these biomarkers to predict the risk of organ dysfunction in sepsis patients, enabling timely implementation of preventive measures that may improve patient outcomes.

The modulation of endothelial glycocalyx by sulodexide on the porcine model of enzymatic endothelial glycocalyx damage - a pilot study

BackgroundSulodexide is a glycosaminoglycan-based drug prescribed to patients with angiopathy. We performed a pilot study to investigate whether sulodexide positively modulates the endothelial glycocalyx (EG) layer and the microcirculation in a porcine model of EG enzymatic damage. The EG is a sugar-based endothelial lining that is involved in the physiology of the capillary wall and the pathogenesis of many diseases.MethodsEG damage was induced in eight piglets by hyaluronidase III and heparanase I given intravenously. Four animals received sulodexide 600 IU intravenously before the enzymes and four animals after the enzymes were administered. Four animals constituted a control group. Sublingual microcirculation by side-stream dark field imaging and plasmatic concentration of syndecan-1 by ELISA were measured at baseline, 20 min after intervention, and at the 40th, and 60th minute onwards. The statistics were performed with a one-way ANOVA test with Turkey's correction for multiple comparisons testing. Timepoint comparison was performed by Student t-test or Mann-Whitney test.ResultsAt baseline, there were no statistically significant differences between the animal groups. After the intervention, the levels of syndecan-1 were significantly lower in the control group. While there were no differences between the two intervention groups. The sublingual microcirculation analysis showed that the DeBacker score was significantly higher in the control group. At 60 min, there was also a statistically significant difference in DeBacker score between the groups (8.1 ± 1.6 mm-1 in the group with enzymes given first and 11 ± 0.92 mm-1 in the group with sulodexide given first, p = 0.03). The analysis of the proportion of perused vessels did not show any statistically significant differences.ConclusionThe results of the study demonstrated a working model of EG damage but no specific action of sulodexide on EG modulation. In the sublingual microcirculation analysis, the sulodexide reduced the fall in absolute tissue perfusion in 60 min.

Deciphering mechanical cues in the microenvironment: from non-malignant settings to tumor progression

The tumor microenvironment functions as a dynamic and intricate ecosystem, comprising a diverse array of cellular and non-cellular components that precisely orchestrate pivotal tumor behaviors, including invasion, metastasis, and drug resistance. While unraveling the intricate interplay between the tumor microenvironment and tumor behaviors represents a tremendous challenge, recent research illuminates a crucial biological phenomenon known as cellular mechanotransduction. Within the microenvironment, mechanical cues like tensile stress, shear stress, and stiffness play a pivotal role by activating mechanosensitive effectors such as PIEZO proteins, integrins, and Yes-associated protein. This activation initiates cascades of intrinsic signaling pathways, effectively linking the physical properties of tissues to their physiological and pathophysiological processes like morphogenesis, regeneration, and immunity. This mechanistic insight offers a novel perspective on how the mechanical cues within the tumor microenvironment impact tumor behaviors. While the intricacies of the mechanical tumor microenvironment are yet to be fully elucidated, it exhibits distinct physical attributes from non-malignant tissues, including elevated solid stresses, interstitial hypertension, augmented matrix stiffness, and enhanced viscoelasticity. These traits exert notable influences on tumor progression and treatment responses, enriching our comprehension of the multifaceted nature of the microenvironment. Through this innovative review, we aim to provide a new lens to decipher the mechanical attributes within the tumor microenvironment from non-malignant contexts, broadening our knowledge on how these factors promote or inhibit tumor behaviors, and thus offering valuable insights to identify potential targets for anti-tumor strategies.

Mapping the FGF2 Interactome Identifies a Functional Proteoglycan Coreceptor

Fibroblast growth factor 2 (FGF2) is a multipotent growth factor and signaling protein that exhibits broad functions across multiple cell types. These functions are often initiated by binding to growth factor receptors and fine-tuned by glycosaminoglycan (GAG)-modified proteins called proteoglycans. The various outputs of FGF2 signaling and functions arise from a dynamic and cell type-specific set of binding partners. However, the interactome of FGF2 has yet to be comprehensively determined. Moreover, the identity of the proteoglycan proteins carrying GAG chains is often overlooked and remains unknown in most cell contexts. Here, we perform peroxidase-catalyzed live cell proximity labeling using an engineered APEX2-FGF2 fusion protein to map the interactome of FGF2. Across two cell lines with established and distinct FGF2-driven functions, we greatly expand upon the known FGF2 interactome, identifying >600 new putative FGF2 interactors. Notably, our results demonstrate a key role for the GAG binding capacity of FGF2 in modulating its interactome.

Sodium, the Vascular Endothelium, and Hypertension: A Narrative Review of Literature

The vascular endothelium and its endothelial glycocalyx contribute to the protection of the endothelial cells from exposure to high levels of sodium and help these structures maintain normal function by regulating vascular permeability due to its buffering effect. The endothelial glycocalyx has negative surface charges that bind sodium and limit sodium entry into cells and the interstitial space. High sodium levels can disrupt this barrier and allow the movement of sodium into cells and extravascular fluid. This can generate reactive oxygen species that inhibit nitric oxide production. This leads to vasospasm and increases intravascular pressures. Overtime vascular remodeling occurs, and this changes the anatomy of blood vessels, their intrinsic stiffness, and their response to vasodilators and results in hypertension. Patients with increased salt sensitivity are potentially at more risk for this sequence of events. Studies on the degradation of the glycocalyx provide insight into the pathogenesis of clinical disorders with vascular involvement, but there is limited information available in the context of higher concentrations of sodium. Data on higher intake of sodium and the imbalance between nitric oxide and reactive oxygen species have been obtained in experimental studies and provide insights into possible outcomes in humans. The current western diet with sodium intake above recommended levels has led to the assessment of sodium sensitivity, which has been used in different populations and could become a practical tool to evaluate patients. This would potentially allow more focused recommendations regarding salt intake. This review will consider the structure of the vascular endothelium, its components, the effect of sodium on it, and the use of the salt blood test mini.

Glycocalyx disruption, endothelial dysfunction and vascular remodeling as underlying mechanisms and treatment targets of chronic venous disease

The glycocalyx is an essential structural and functional component of endothelial cells. Extensive hemodynamic changes cause endothelial glycocalyx disruption and vascular dysfunction, leading to multiple arterial and venous disorders. Chronic venous disease (CVD) is a common disorder of the lower extremities with major health and socio-economic implications, but complex pathophysiology. Genetic aberrations accentuated by environmental factors, behavioral tendencies, and hormonal disturbances promote venous reflux, valve incompetence, and venous blood stasis. Increased venous hydrostatic pressure and changes in shear-stress cause glycocalyx injury, endothelial dysfunction, secretion of adhesion molecules, leukocyte recruitment/activation, and release of cytokines, chemokines, and hypoxia-inducible factor, causing smooth muscle cell switch from contractile to synthetic proliferative phenotype, imbalance in matrix metalloproteinases (MMPs), degradation of collagen and elastin, and venous tissue remodeling, leading to venous dilation and varicose veins. In the advanced stages of CVD, leukocyte infiltration of the vein wall causes progressive inflammation, fibrosis, disruption of junctional proteins, accumulation of tissue metabolites and reactive oxygen and nitrogen species, and iron deposition, leading to skin changes and venous leg ulcer (VLU). CVD management includes compression stockings, venotonics, and surgical intervention. In addition to its antithrombotic and fibrinolytic properties, literature suggests sulodexide benefits in reducing inflammation, promoting VLU healing, improving endothelial function, exhibiting venotonic properties, and inhibiting MMP-9. Understanding the role of glycocalyx, endothelial dysfunction, and vascular remodeling should help delineate the underlying mechanisms and develop improved biomarkers and targeted therapy for CVD and VLU.

Effect on Syndecan-1 and Hyaluronan Levels Depending on Multiple Organ Failure, Coagulopathy and Survival: An Observational Study in Major Trauma Patients

Background: Major trauma, as well as traumatic hemorrhagic shock go along with early damage to the endothelial glycocalyx (EG). Shed glycocalyx constituents can activate the innate immune system and aggravate secondary injury. Subsequently, we investigated the relationship between glycocalyx shedding and the occurrence of coagulopathy, multiple organ failure (MOF) and outcome in our cohort after severe trauma. Methods: We included multiple trauma patients, as defined by Injury Severity Score (ISS). Polytraumatized patients must have arrived in our level 1 trauma center within 60 min after trauma. Retrospectively, patients were assigned to predefined clinical conditions, based on injury severity (ISS ≥ 16 points), multiple organ failure (MOF score ≥ 6 points), need for massive transfusion (≥10 RBC units/first 24 h), coagulopathy (prothrombin time < 70% at 0 h) and survival (90-day survival). Syndecan-1 (Sdc-1) and hyaluronan (HA) plasma concentrations were evaluated immediately (0 h), 6 h and 12 h after trauma. Results: 49 patients (mean ISS 35.7 ± 12.1 SD, mean age 45.78 ± 15.6 SD) were included in this study. A total of 37 patients (75.5%) survived, while 12 patients died within the observation period of 90 days after trauma (24.5%). A total of 77% of all patients suffered multiple organ failure (MOF score ≥ 6, n = 30). Initial prothrombin time at 0 h was <70% in 31 patients. Plasma concentrations of circulating both glycocalyx constituents showed a significant increase over the first 12 h after trauma (p = 0.001; p = 0.008). Patients with multiple organ failure showed significantly increased hyaluronan concentrations at all three time points (p = 0.007/0.006/<0.001), and the syndecan-1 levels were significantly elevated 12 h after trauma in the MOF group (p = 0.01). Patients with coagulopathy on admission exhibited significantly higher hyaluronan levels at 12 h (p = 0.042). Non-survivors showed significantly increased syndecan-1 levels at 12 h after trauma (p = 0.024). Conclusions: Glycocalyx shedding occurs immediately after major trauma. Coagulopathy is associated with significantly increased plasma hyaluronan. Further, significant changes in plasma concentrations within the first 12 h help to identify subgroups at risk for developing MOF and death.

Co-Therapy with S1P and Heparan Sulfate Derivatives to Restore Endothelial Glycocalyx and Combat Pro-Atherosclerotic Endothelial Dysfunction

Endothelial cell (EC) glycocalyx (GCX) shedding due to disturbed blood flow and chemical factors leads to low-density lipoprotein infiltration and reduced nitric oxide synthesis, causing vascular dysfunction and atherosclerosis. This study evaluates a novel therapy combining sphingosine-1-phosphate (S1P) and heparin (heparan sulfate derivative). We hypothesized that heparin/S1P would repair mechanically damaged EC GCX in disturbed flow (DF) regions and restore anti-atherosclerotic mechanotransduction function, addressing cardiovascular disease. We used a parallel-plate flow chamber to simulate flow conditions in vitro and a partial carotid ligation mouse model to mimic DF in vivo. Heparin and albumin-bound S1P were administered to assess their reparative effects on the endothelial GCX. Immunocytochemistry, fluorescent staining, confocal microscopy, cellular alignment studies, and ultrasound were performed to evaluate EC function and endothelial-dependent vascular function. Barrier functionality was assessed via macrophage uptake. Heparin/S1P mechanism-of-action insights were gained through fluid dynamics simulations and staining of GCX synthesis enzyme as well as S1P receptor. Statistical analyses validated results. In vitro data showed that heparin/S1P therapy improves the function of DF-conditioned ECs by restoring EC GCX and promoting EC alignment and elevated vasodilator eNOS (endothelial-type nitric oxide synthase) expression. The in vivo studies confirmed GCX degradation, increased vessel inflammation and hyperpermeability, and vessel wall thickening in the partially ligated left carotid artery. Heparin/S1P treatment restored GCX in the left carotid artery, enhancing GCX thickness and coverage of the blood vessel wall. This work advances a new approach to regenerating the EC GCX and restoring its function in ECs under DF conditions.

Prospective Evaluation of the Peripheral Perfusion Index in Assessing the Organ Dysfunction and Prognosis of Adult Patients With Sepsis in the ICU

Background: The peripheral perfusion index (PI) reflects microcirculatory blood flow perfusion and indicates the severity and prognosis of sepsis. Method: The cohort comprised 208 patients admitted to the intensive care unit (ICU) with infection, among which 117 had sepsis. Demographics, medication history, ICU variables, and laboratory indexes were collected. Primary endpoints were in-hospital mortality and 28-day mortality. Secondary endpoints included organ function variables (coagulation function, liver function, renal function, and myocardial injury), lactate concentration, mechanical ventilation time, and length of ICU stay. Univariate and multivariate analyses were conducted to assess the associations between the PI and clinical outcomes. Sensitivity analyses were performed to explore the associations between the PI and organ functions in the sepsis and nonsepsis groups. Result: The PI was negatively associated with in-hospital mortality (odds ratio [OR] 0.29, 95% confidence interval [CI] 0.15 to 0.55), but was not associated with 28-day mortality. The PI was negatively associated with the coagulation markers prothrombin time (PT) (β -0.36, 95% CI -0.59 to 0.13) and activated partial thromboplastin time (APTT) (β -1.08, 95% CI -1.86 to 0.31), and the myocardial injury marker cardiac troponin I (cTnI) (β -2085.48, 95% CI -3892.35 to 278.61) in univariate analysis, and with the PT (β -0.36, 95% CI -0.60 to 0.13) in multivariate analysis. The PI was negatively associated with the lactate concentration (β -0.57, 95% CI -0.95 to 0.19), mechanical ventilation time (β -23.11, 95% CI -36.54 to 9.69), and length of ICU stay (β -1.28, 95% CI -2.01 to 0.55). Sensitivity analyses showed that the PI was significantly associated with coagulation markers (PT and APTT) and a myocardial injury marker (cTnI) in patients with sepsis, suggesting that the associations between the PI and organ function were stronger in the sepsis group than the nonsepsis group. Conclusion: The PI provides new insights for assessing the disease severity, short-term prognosis, and organ function damage in ICU patients with sepsis, laying a theoretical foundation for future research.

Glycocalyx cleavage boosts erythrocytes aggregation

The glycocalyx is a complex layer of carbohydrate and protein molecules that surrounds the cell membrane of many types of mammalian cells. It serves several important functions, including cell adhesion and communication, and maintain cell shape and stability, especially in the case of erythrocytes. Alteration of glycocalyx composition represents a cardiovascular health threatening. For example, in diabetes mellitus glycocalyx of erythrocytes and of endothelial cells is known to be impaired, a potential source of blood occlusion in microcirculation, which may lead to blindness, and renal failure of patients. The impact of glycocalyx impairment on erythrocyte aggregation remains a largely unexplored research area. We conduct here in vitro-experiments in microfluidic devices in order to investigate erythrocytes aggregation incubated with amylase, an enzyme that partially breaks down glycocalyx molecules. It is found that incubation of erythrocytes by amylase leads to a dramatic increase of their aggregation and stability and alters the aggregates morphologies. Confocal microscopy analysis reveals a significant degradation of the glycocalyx layer, correlated with enhanced erythrocytes aggregation. An increased erythrocyte aggregation in vivo should affect oxygen and other metabolites delivery to organs and tissues. This study brings new elements about elucidation of microscopic origins of erythrocyte aggregation and their potential impact on cardiovascular pathologies.

The Crucial Triad: Endothelial Glycocalyx, Oxidative Stress, and Inflammation in Cardiac Surgery-Exploring the Molecular Connections

Since its introduction, the number of heart surgeries has risen continuously. It is a high-risk procedure, usually involving cardiopulmonary bypass, which is associated with an inflammatory reaction that can lead to perioperative and postoperative organ dysfunction. The extent of complications following cardiac surgery has been the focus of interest for several years because of their impact on patient outcomes. Recently, numerous scientific efforts have been made to uncover the complex mechanisms of interaction between inflammation, oxidative stress, and endothelial dysfunction that occur after cardiac surgery. Numerous factors, such as surgical and anesthetic techniques, hypervolemia and hypovolemia, hypothermia, and various drugs used during cardiac surgery trigger the development of systemic inflammatory response and the release of oxidative species. They affect the endothelium, especially endothelial glycocalyx (EG), a thin surface endothelial layer responsible for vascular hemostasis, its permeability and the interaction between leukocytes and endothelium. This review highlights the current knowledge of the molecular mechanisms involved in endothelial dysfunction, particularly in the degradation of EG. In addition, the major inflammatory events and oxidative stress responses that occur in cardiac surgery, their interaction with EG, and the clinical implications of these events have been summarized and discussed in detail. A better understanding of the complex molecular mechanisms underlying cardiac surgery, leading to endothelial dysfunction, is needed to improve patient management during and after surgery and to develop effective strategies to prevent adverse outcomes that complicate recovery.

Developing and Benchmarking Sulfate and Sulfamate Force Field Parameters via Ab Initio Molecular Dynamics Simulations To Accurately Model Glycosaminoglycan Electrostatic Interactions

Glycosaminoglycans (GAGs) are negatively charged polysaccharides found on cell surfaces, where they regulate transport pathways of foreign molecules toward the cell. The structural and functional diversity of GAGs is largely attributed to varied sulfation patterns along the polymer chains, which makes understanding their molecular recognition mechanisms crucial. Molecular dynamics (MD) simulations, thanks to their unmatched microscopic resolution, have the potential to be a reference tool for exploring the patterns responsible for biologically relevant interactions. However, the capability of molecular dynamics force fields used in biosimulations to accurately capture sulfation-specific interactions is not well established, partly due to the intrinsic properties of GAGs that pose challenges for most experimental techniques. In this work, we evaluate the performance of molecular dynamics force fields for sulfated GAGs by studying ion pairing of Ca2+ to sulfated moieties─N-methylsulfamate and methylsulfate─that resemble N- and O-sulfation found in GAGs, respectively. We tested available nonpolarizable (CHARMM36 and GLYCAM06) and explicitly polarizable (Drude and AMOEBA) force fields, and derived new implicitly polarizable models through charge scaling (prosECCo75 and GLYCAM-ECC75) that are consistent with our developed "charge-scaling" framework. The calcium-sulfamate/sulfate interaction free energy profiles obtained with the tested force fields were compared against reference ab initio molecular dynamics (AIMD) simulations, which serve as a robust alternative to experiments. AIMD simulations indicate that the preferential Ca2+ binding mode to sulfated GAG groups is solvent-shared pairing. Only our scaled-charge models agree satisfactorily with the AIMD data, while all other force fields exhibit poorer agreement, sometimes even qualitatively. Surprisingly, even explicitly polarizable force fields display a notable disagreement with the AIMD data, likely attributed to difficulties in their optimization and possible inherent limitations in depicting high-charge-density ion interactions accurately. Finally, the underperforming force fields lead to unrealistic aggregation of sulfated saccharides, which qualitatively disagrees with our understanding of the soft glycocalyx environment. Our results highlight the importance of accurately treating electronic polarization in MD simulations of sulfated GAGs and caution against over-reliance on currently available models without thorough validation and optimization.

Low or oscillatory shear stress and endothelial permeability in atherosclerosis

Endothelial shear stress is a tangential stress derived from the friction of the flowing blood on the endothelial surface of the arterial wall and is expressed in units of force/unit area (dyne/cm2). Branches and bends of arteries are exposed to complex blood flow patterns that generate low or oscillatory endothelial shear stress, which impairs glycocalyx integrity, cytoskeleton arrangement and endothelial junctions (adherens junctions, tight junctions, gap junctions), thus increasing endothelial permeability. The lipoproteins and inflammatory cells penetrating intima due to the increased endothelial permeability characterizes the pathological changes in early stage of atherosclerosis. Endothelial cells are critical sensors of shear stress, however, the mechanisms by which the complex shear stress regulate endothelial permeability in atherosclerosis remain unclear. In this review, we focus on the molecular mechanisms of the endothelial permeability induced by low or oscillatory shear stress, which will shed a novel sight in early stage of atherosclerosis.

Extracellular glypican-1 affects tumor progression and prognosis in esophageal cancer

INTRODUCTION

Cells are covered with a glycan surface layer that is referred to as the glycocalyx (GCX). It has been reported that the formation of the GCX is promoted on cancer cells and is associated with tumor growth and metastasis. Heparan sulfate proteoglycan glypican-1 (GPC1) is a core protein of the GCX that is overexpressed in esophageal squamous cell carcinoma (ESCC) and is involved in the development and progression of cancer cells. The purpose of the present study is to analyze the utility of GPC1 as a new biomarker ralated to glycocalyx that reflects therapeutic effect and prognosis of ESCC.

METHODS

We measured the concentration of GPC1 protein in preoperative plasma from advanced esophageal cancer patients and examined its relationships with clinicopathological factors and therapeutic efficacy, and the effects of extracellular GPC1 were investigated.

RESULTS

The following clinical factors were significantly correlated with the preoperative high GPC1 concentration: male, tumor size ≥30 mm, venous invasion, pT factor ≥2, pStage ≥3, residual tumor, and distant metastatic recurrence. Both overall and recurrence-free survival were significantly worse in the high GPC1 group. Extracellular GPC1 protein concentration reflected intracellular GPC1 expression. Furthermore, we examined the effects of extracellular recombinant human (rh)GPC1 on ESCC cells, and found that extracellular rhGPC1 affects cell motility, including migration and invasion.

CONCLUSIONS

These results demonstrated the utility of extracellular GPC1 as a biomarker, which can be assayed from a less invasive blood sample-based liquid biopsy. Extracellular GPC1 protein plays a role in both tumor cell motility and cancer progression. Thus, plasma GPC1 is a useful biomarker for esophageal cancer progression and may be a potential candidate of therapeutic target.

A comprehensive physics-based model for the brachial Artery's full flow mediated dilation (FMD) response observed during the FMD test

In this study, a physics-based model is developed to describe the entire flow mediated dilation (FMD) response. A parameter quantifying the arterial wall's tendency to recover arises from the model, thereby providing a more elaborate description of the artery's physical state, in concert with other parameters characterizing mechanotransduction and structural aspects of the arterial wall. The arterial diameter's behavior throughout the full response is successfully reproduced by the model. Experimental FMD response data were obtained from healthy volunteers. The model's parameters are then adjusted to yield the closest match to the observed experimental response, hence delivering the parameter values pertaining to each subject. This study establishes a foundation based on which future potential clinical applications can be introduced, where endothelial function and general cardiovascular health are inexpensively and noninvasively quantified.

ECM Microenvironment in Vascular Homeostasis: New Targets for Atherosclerosis

Alterations in vascular extracellular matrix (ECM) components, interactions, and mechanical properties influence both the formation and stability of atherosclerotic plaques. This review discusses the contribution of the ECM microenvironment in vascular homeostasis and remodeling in atherosclerosis, highlighting Cartilage oligomeric matrix protein (COMP) and its degrading enzyme ADAMTS7 as examples, and proposes potential avenues for future research aimed at identifying novel therapeutic targets for atherosclerosis based on the ECM microenvironment.

Polyphenol-Reinforced Glycocalyx-Like Hydrogel Coating Induced Myocardial Regeneration and Immunomodulation

Although minimally invasive interventional occluders can effectively seal heart defect tissue, they still have some limitations, including poor endothelial healing, intense inflammatory response, and thrombosis formation. Herein, a polyphenol-reinforced medicine/peptide glycocalyx-like coating was prepared on cardiac occluders. A coating consisting of carboxylated chitosan, epigallocatechin-3-gallate (EGCG), tanshinone IIA sulfonic sodium (TSS), and hyaluronic acid grafted with 3-aminophenylboronic acid was prepared. Subsequently, the mercaptopropionic acid-GGGGG-Arg-Glu-Asp-Val peptide was grafted by the thiol-ene "click" reaction. The coating showed good hydrophilicity and free radical-scavenging ability and could release EGCG-TSS. The results of biological experiments suggested that the coating could reduce thrombosis by promoting endothelialization, and promote myocardial repair by regulating the inflammatory response. The functions of regulating cardiomyocyte apoptosis and metabolism were confirmed, and the inflammatory regulatory functions of the coating were mainly dependent on the NF-kappa B and TNF signaling pathway.

Cardiovascular Risk in Patients with Inflammatory Bowel Diseases-The Role of Endothelial Dysfunction

Inflammatory bowel disease (IBD) is associated with an increased risk of cardiovascular disease (CVD). Cardiovascular pathology in people with IBD has not been well studied to date, and a direct link between cardiovascular events and IBD has not been established. The mechanisms underlying this association include the parallel and dynamic interaction of inflammation, modulation of the composition of the gut microbiota, endothelial dysfunction, thrombogenicity, and increased endothelial and epithelial permeability. Endothelial dysfunction is a common aspect of the pathogenesis of IBD and atherosclerotic CVD and can be considered one of the most important factors leading to the development and progression of cardiovascular pathology in patients with IBD. The purpose of this literature review is to describe the mechanisms underlying the development of endothelial dysfunction and disorders of the structure and function of the gut-vascular barrier in the pathogenesis of the cardiovascular manifestation of IBD.

Biomimetic strategies for the deputization of proteoglycan functions

Proteoglycans (PGs), which have glycosaminoglycan chains attached to their protein cores, are essential for maintaining the morphology and function of healthy body tissues. Extracellular PGs perform various functions, classified into the following four categories: i) the modulation of tissue mechanical properties; ii) the regulation and protection of the extracellular matrix; iii) protein sequestration; and iv) the regulation of cell signaling. The depletion of PGs may significantly impair tissue function, encompassing compromised mechanical characteristics and unregulated inflammatory responses. Since PGs play critical roles in the function of healthy tissues and their synthesis is complex, the development of PG mimetic molecules that recapitulate PG functions for tissue engineering and therapeutic applications has attracted the interest of researchers for more than 20 years. These approaches have ranged from semisynthetic graft copolymers to recombinant PG domains produced by cells that have undergone genetic modifications. This review discusses some essential extracellular PG functions and approaches to mimicking these functions.

The Glycocalyx: The Importance of Sugar Coating the Blood-Brain Barrier

The endothelial glycocalyx (GCX), located on the luminal surface of vascular endothelial cells, is composed of glycoproteins, proteoglycans, and glycosaminoglycans. It plays a pivotal role in maintaining blood-brain barrier (BBB) integrity and vascular health within the central nervous system (CNS), influencing critical processes such as blood flow regulation, inflammation modulation, and vascular permeability. While the GCX is ubiquitously expressed on the surface of every cell in the body, the GCX at the BBB is highly specialized, with a distinct composition of glycans, physical structure, and surface charge when compared to GCX elsewhere in the body. There is evidence that the GCX at the BBB is disrupted and partially shed in many diseases that impact the CNS. Despite this, the GCX has yet to be a major focus of therapeutic targeting for CNS diseases. This review examines diverse model systems used in cerebrovascular GCX-related research, emphasizing the importance of selecting appropriate models to ensure clinical relevance and translational potential. This review aims to highlight the importance of the GCX in disease and how targeting the GCX at the BBB specifically may be an effective approach for brain specific targeting for therapeutics.

Impaired instructive and protective barrier functions of the endothelial cell glycocalyx pericellular matrix is impacted in COVID-19 disease

The aim of this study was to review the roles of endothelial cells in normal tissue function and to show how COVID-19 disease impacts on endothelial cell properties that lead to much of its associated symptomatology. This places the endothelial cell as a prominent cell type to target therapeutically in the treatment of this disorder. Advances in glycosaminoglycan analytical techniques and functional glycomics have improved glycosaminoglycan mimetics development, providing agents that can more appropriately target various aspects of the behaviour of the endothelial cell in-situ and have also provided polymers with potential to prevent viral infection. Thus, promising approaches are being developed to combat COVID-19 disease and the plethora of symptoms this disease produces. Glycosaminoglycan mimetics that improve endothelial glycocalyx boundary functions have promising properties in the prevention of viral infection, improve endothelial cell function and have disease-modifying potential. Endothelial cell integrity, forming tight junctions in cerebral cell populations in the blood-brain barrier, prevents the exposure of the central nervous system to circulating toxins and harmful chemicals, which may contribute to the troublesome brain fogging phenomena reported in cognitive processing in long COVID disease.

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.

Syndecan-1 Levels in Females with Active Rheumatoid Arthritis

Background: The relationship between serum glycoprotein syndecan-1 and disease activity in rheumatoid arthritis (RA) is still unknown. This study aimed to evaluate whether serum syndecan-1 concentrations are associated with moderate/severe disease activity. Methods: Study Design: This was a cross-sectional study. Seventy-five adult women with RA were classified into (a) moderate/severe RA based on the disease activity score, using the erythrocyte sedimentation rate (DAS28-ESR ≥ 3.2, n = 50), and (b) RA in remission (DAS28-ESR < 2.6, n = 25). Twenty-five healthy women were taken as the reference group. Syndecan-1 levels were determined using enzyme-linked immunosorbent assay (ELISA). High values of serum syndecan-1 levels (≥24 ng/mL) were used to identify the utility values of this biomarker. Results: The patients with RA had higher levels of syndecan-1 than the controls (p < 0.001). RA patients with active disease had higher syndecan-1 levels than RA patients in remission (57.6 vs. 23.5 ng/mL, respectively; p = 0.002). High syndecan-1 concentrations demonstrated the following utility values for identifying disease activity: sensitivity, 84% (95%CI: 71-93); specificity, 52% (95%CI: 31-72); positive predictive value, 78% (95%CI: 70-84); and negative predictive value, 62% (95%CI: 44-77). Conclusions: High syndecan-1 levels have good sensitivity and positive predictive value for identifying disease activity; however, their specificity is limited. Future prospective studies are needed to assess whether syndecan-1 levels can predict treatment failure in RA.

Unraveling neurovascular mysteries: the role of endothelial glycocalyx dysfunction in Alzheimer's disease pathogenesis

While cardiovascular disease, cancer, and human immunodeficiency virus (HIV) mortality rates have decreased over the past 20 years, Alzheimer's Disease (AD) deaths have risen by 145% since 2010. Despite significant research efforts, effective AD treatments remain elusive due to a poorly defined etiology and difficulty in targeting events that occur too downstream of disease onset. In hopes of elucidating alternative treatment pathways, now, AD is commonly being more broadly defined not only as a neurological disorder but also as a progression of a variety of cerebrovascular pathologies highlighted by the breakdown of the blood-brain barrier. The endothelial glycocalyx (GCX), which is an essential regulator of vascular physiology, plays a crucial role in the function of the neurovascular system, acting as an essential vascular mechanotransducer to facilitate ultimate blood-brain homeostasis. Shedding of the cerebrovascular GCX could be an early indication of neurovascular dysfunction and may subsequently progress neurodegenerative diseases like AD. Recent advances in in vitro modeling, gene/protein silencing, and imaging techniques offer new avenues of scrutinizing the GCX's effects on AD-related neurovascular pathology. Initial studies indicate GCX degradation in AD and other neurodegenerative diseases and have begun to demonstrate a possible link to GCX loss and cerebrovascular dysfunction. This review will scrutinize the GCX's contribution to known vascular etiologies of AD and propose future work aimed at continuing to uncover the relationship between GCX dysfunction and eventual AD-associated neurological deterioration.

Metabolic-Glycoengineering-Enabled Molecularly Specific Acoustic Tweezing Cytometry for Targeted Mechanical Stimulation of Cell Surface Sialoglycans

In this study, we developed a novel type of dibenzocyclooctyne (DBCO)-functionalized microbubbles (MBs) and validated their attachment to azide-labelled sialoglycans on human pluripotent stem cells (hPSCs) generated by metabolic glycoengineering (MGE). This enabled the application of mechanical forces to sialoglycans on hPSCs through molecularly specific acoustic tweezing cytometry (mATC), that is, displacing sialoglycan-anchored MBs using ultrasound (US). It was shown that subjected to the acoustic radiation forces of US pulses, sialoglycan-anchored MBs exhibited significantly larger displacements and faster, more complete recovery after each pulse than integrin-anchored MBs, indicating that sialoglycans are more stretchable and elastic than integrins on hPSCs in response to mechanical force. Furthermore, stimulating sialoglycans on hPSCs using mATC reduced stage-specific embryonic antigen-3 (SSEA-3) and GD3 expression but not OCT4 and SOX2 nuclear localization. Conversely, stimulating integrins decreased OCT4 nuclear localization but not SSEA-3 and GD3 expression, suggesting that mechanically stimulating sialoglycans and integrins initiated distinctive mechanoresponses during the early stages of hPSC differentiation. Taken together, these results demonstrated that MGE-enabled mATC uncovered not only different mechanical properties of sialoglycans on hPSCs and integrins but also their different mechanoregulatory impacts on hPSC differentiation, validating MGE-based mATC as a new, powerful tool for investigating the roles of glycans and other cell surface biomolecules in mechanotransduction.

Multivalent, calcium-independent binding of surfactant protein A and D to sulfated glycosaminoglycans of the alveolar epithelial glycocalyx

Lung surfactant collectins, surfactant protein A (SP-A) and D (SP-D), are oligomeric C-type lectins involved in lung immunity. Through their carbohydrate recognition domain, they recognize carbohydrates at pathogen surfaces and initiate lung innate immune response. Here, we propose that they may also be able to bind to other carbohydrates present in typical cell surfaces, such as the alveolar epithelial glycocalyx. To test this hypothesis, we analyzed and quantified the binding affinity of SP-A and SP-D to different sugars and glycosaminoglycans (GAGs) by microscale thermophoresis (MST). In addition, by changing the calcium concentration, we aimed to characterize any consequences on the binding behavior. Our results show that both oligomeric proteins bind with high affinity (in nanomolar range) to GAGs, such as hyaluronan (HA), heparan sulfate (HS) and chondroitin sulfate (CS). Binding to HS and CS was calcium-independent, as it was not affected by changing calcium concentration in the buffer. Quantification of GAGs in bronchoalveolar lavage (BAL) fluid from animals deficient in either SP-A or SP-D showed changes in GAG composition, and electron micrographs showed differences in alveolar glycocalyx ultrastructure in vivo. Taken together, SP-A and SP-D bind to model sulfated glycosaminoglycans of the alveolar epithelial glycocalyx in a multivalent and calcium-independent way. These findings provide a potential mechanism for SP-A and SP-D as an integral part of the alveolar epithelial glycocalyx binding and interconnecting free GAGs, proteoglycans, and other glycans in glycoproteins, which may influence glycocalyx composition and structure.NEW & NOTEWORTHY SP-A and SP-D function has been related to innate immunity of the lung based on their binding to sugar residues at pathogen surfaces. However, their function in the healthy alveolus was considered as limited to interaction with surfactant lipids. Here, we demonstrated that these proteins bind to glycosaminoglycans present at typical cell surfaces like the alveolar epithelial glycocalyx. We propose a model where these proteins play an important role in interconnecting alveolar epithelial glycocalyx components.

EFFECT OF MIR-21-3P ON INTESTINAL INJURY IN RATS WITH TRAUMATIC HEMORRHAGIC SHOCK RESUSCITATED WITH THE SODIUM BICARBONATE RINGER'S SOLUTION

ABSTRACT

Background : This study aims to determine the impact and mechanism of miR-21-3p on intestinal injury and intestinal glycocalyx during fluid resuscitation in traumatic hemorrhagic shock (THS), and the different impacts of sodium lactate Ringer's solution (LRS) and sodium bicarbonate Ringer's solution (BRS) for resuscitation on intestinal damage. Methods : A rat model of THS was induced by hemorrhage from the left femur fracture. The pathological changes of intestinal tissues and glycocalyx structure were observed by hematoxylin-eosin staining and transmission electron microscope. MiR-21-3p expression in intestinal tissues was detected by real-time quantitative polymerase chain reaction. The expression of glycocalyx-, cell junction-, and PI3K/Akt/NF-κB signaling pathway-related proteins was analyzed by western blot. Results : MiR-21-3p expression was increased in THS rats, which was suppressed by resuscitation with BRS. BRS or LRS aggravated the intestinal injury and damaged intestinal glycocalyx in THS rats. The expression of SDC-1, HPA, β-catenin, MMP2, and MMP9 was upregulated, the expression of E-cad was downregulated, and the PI3K/Akt/NF-κB signaling pathway was activated in THS rats, which were further aggravated by BRS or LRS. The adverse effect of LRS was more serious than BRS. MiR-21-3p overexpression deteriorated the injury of intestinal tissues and intestinal glycocalyx; increased the expression of SDC-1, HPA, β-catenin, MMP2, and MMP9 while decreasing E-cad expression; and activated the PI3K/Akt/NF-κB signaling pathway in BRS-resuscitated THS rats. Conclusion : MiR-21-3p aggravated intestinal tissue injury and intestinal glycocalyx damage through activating PI3K/Akt/NF-κB signaling pathway in rats with THS resuscitated with BRS.

Insights into the Molecular Mechanism of Endothelial Glycocalyx Dysfunction during Heart Surgery

The endothelial glycocalyx (EGC) is a layer of proteoglycans (associated with glycosaminoglycans) and glycoproteins, which adsorbs plasma proteins on the luminal surface of endothelial cells. Its main function is to participate in separating the circulating blood from the inner layers of the vessels and the surrounding tissues. Physiologically, the EGC stimulates mechanotransduction, the endothelial charge, thrombocyte adhesion, leukocyte tissue recruitment, and molecule extravasation. Hence, severe impairment of the EGC has been implicated in various pathological conditions, including sepsis, diabetes, chronic kidney disease, inflammatory disorders, hypernatremia, hypervolemia, atherosclerosis, and ischemia/reperfusion injury. Moreover, alterations in EGC have been associated with altered responses to therapeutic interventions in conditions such as cardiovascular diseases. Investigation into the function of the glycocalyx has expanded knowledge about vascular disorders and indicated the need to consider new approaches in the treatment of severe endothelial dysfunction. This review aims to present the current understanding of the molecular mechanisms underlying cardiovascular diseases and to elucidate the impact of heart surgery on EGC dysfunction.

Conformational changes in the Niemann-Pick type C1 protein NCR1 drive sterol translocation

The membrane protein Niemann-Pick type C1 (NPC1, named NCR1 in yeast) is central to sterol homeostasis in eukaryotes. Saccharomyces cerevisiae NCR1 is localized to the vacuolar membrane, where it is suggested to carry sterols across the protective glycocalyx and deposit them into the vacuolar membrane. However, documentation of a vacuolar glycocalyx in fungi is lacking, and the mechanism for sterol translocation has remained unclear. Here, we provide evidence supporting the presence of a glycocalyx in isolated S. cerevisiae vacuoles and report four cryo-EM structures of NCR1 in two distinct conformations, named tense and relaxed. These two conformations illustrate the movement of sterols through a tunnel formed by the luminal domains, thus bypassing the barrier presented by the glycocalyx. Based on these structures and on comparison with other members of the Resistance-Nodulation-Division (RND) superfamily, we propose a transport model that links changes in the luminal domains with a cycle of protonation and deprotonation within the transmembrane region of the protein. Our model suggests that NPC proteins work by a generalized RND mechanism where the proton motive force drives conformational changes in the transmembrane domains that are allosterically coupled to luminal/extracellular domains to promote sterol transport.

Lack of Laminar Shear Stress Facilitates the Endothelial Uptake of Very Small Superparamagnetic Iron Oxide Nanoparticles by Modulating the Endothelial Surface Layer

Purpose

To study whether the absence of laminar shear stress (LSS) enables the uptake of very small superparamagnetic iron oxide nanoparticles (VSOP) in endothelial cells by altering the composition, size, and barrier function of the endothelial surface layer (ESL).

Methods and Results

A quantitative particle exclusion assay with living human umbilical endothelial cells using spinning disc confocal microscopy revealed that the dimension of the ESL was reduced in cells cultivated in the absence of LSS. By combining gene expression analysis, flow cytometry, high pressure freezing/freeze substitution immuno-transmission electron microscopy, and confocal laser scanning microscopy, we investigated changes in ESL composition. We found that increased expression of the hyaluronan receptor CD44 by absence of shear stress did not affect the uptake rate of VSOPs. We identified collagen as a previously neglected component of ESL that contributes to its barrier function. Experiments with inhibitor halofuginone and small interfering RNA (siRNA) demonstrated that suppression of collagen expression facilitates VSOP uptake in endothelial cells grown under LSS.

Conclusion

The absence of laminar shear stress disturbs the barrier function of the ESL, facilitating membrane accessibility and endocytic uptake of VSOP. Collagen, a previously neglected component of ESL, contributes to its barrier function.

Cell Surface Parameters for Accessing Neutrophil Activation Level with Atomic Force Microscopy

In this study, we examine the topography and adhesion images of the cell surface of neutrophils during the activation process. Our analysis of cell surface parameters indicates that the most significant changes in neutrophils occur within the first 30 min of activation, suggesting that reactive oxygen species may require approximately this amount of time to activate the cells. Interestingly, we observed surface granular structure as early as 10 min after neutrophil activation when examining atomic force microscopy images. This finding aligns with the reorganization observed within the cells under confocal laser scanning microscopy. By analyzing the cell surface images of adhesion, we identified three spatial surface parameters that correlate with the activation time. This finding enables us to estimate the degree of activation by using atomic force microscopy maps of the cell surface.

The mitochondrial signature of cultured endothelial cells in sepsis: Identifying potential targets for treatment

Sepsis is the most common cause of death from infection in the world. Unfortunately, there is no specific treatment for patients with sepsis, and management relies on infection control and support of organ function. A better understanding of the underlying pathophysiology of this syndrome will help to develop innovative therapies. In this regard, it has been widely reported that endothelial cell activation and dysfunction are major contributors to the development of sepsis. This review aims to provide a comprehensive overview of emerging findings highlighting the prominent role of mitochondria in the endothelial response in in vitro experimental models of sepsis. Additionally, we discuss potential mitochondrial targets that have demonstrated protective effects in preclinical investigations against sepsis. These promising findings hold the potential to pave the way for future clinical trials in the field.

Hyaluronan-arginine enhanced and dynamic interaction emerges from distinctive molecular signature due to electrostatics and side-chain specificity

Hyaluronan is a natural carbohydrate polymer with a negative charge that fosters gel-like conditions crucial for its cellular functions and industrial applications. As a recognized ligand for proteins, understanding their mutual interactions provides solid ground to tune hyaluronan's gel properties using biocompatible peptides. This work employs NMR and molecular dynamics simulations to identify molecular motifs relevant to hyaluronan-peptide interactions using arginine, lysine, and glycine oligopeptides. Arginine-rich peptides exhibit the strongest binding to hyaluronan according to chemical shift perturbation measurements, followed distantly by the similarly charged lysine. This difference highlights the significance of electrostatics and the peculiarities of the guanidinium side chain in arginine, capable of non-polar interactions that further stabilize the binding. Additional nuclear Overhauser effect measurements do not show stable interaction partners, precluding strong and well-defined complexes. Finally, molecular simulations support our findings and show an extended but significant interaction region, especially for arginine, responsible for the observed enhanced binding, which can also promote cross-linking of hyaluronan polymers. Our findings pave the way for optimizing biocompatible peptides to alter hyaluronan gels' properties efficiently and also explain why hyaluronan-protein interaction typically involves positively charged arginine-rich regions also capable of forming hydrogen bonds and non-polar interactions.

Heparan Sulfate Modulation Affects Breast Cancer Cell Adhesion and Transmigration across In Vitro Blood-Brain Barrier

The disruption of endothelial heparan sulfate (HS) is an early event in tumor cell metastasis across vascular barriers, and the reinforcement of endothelial HS reduces tumor cell adhesion to endothelium. Our recent study showed that while vascular endothelial growth factor (VEGF) greatly reduces HS at an in vitro blood-brain barrier (BBB) formed by human cerebral microvascular endothelial cells (hCMECs), it significantly enhances HS on a breast cancer cell, MDA-MB-231 (MB231). Here, we tested that this differential effect of VEGF on the HS favors MB231 adhesion and transmigration. We also tested if agents that enhance endothelial HS may affect the HS of MB231 and reduce its adhesion and transmigration. To test these hypotheses, we generated an in vitro BBB by culturing hCMECs on either a glass-bottom dish or a Transwell filter. We first quantified the HS of the BBB and MB231 after treatment with VEGF and endothelial HS-enhancing agents and then quantified the adhesion and transmigration of MB231 across the BBB after pretreatment with these agents. Our results demonstrated that the reduced/enhanced BBB HS and enhanced/reduced MB231 HS increase/decrease MB231 adhesion to and transmigration across the BBB. Our findings suggest a therapeutic intervention by targeting the HS-mediated breast cancer brain metastasis.