The role of endothelial glycocalyx in health and disease

The endothelial surface layer-glycocalyx - Universal nano-infrastructure is fundamental to physiology, cell traffic and a complementary neural network

The glycocalyx and its associated endothelial surface layer which lines all cell membranes and most tissues, dwarfs the phospholipid membrane of cells in extent. Its major components are sulphated polymers like heparan and chondroitin sulphates and hyaluronic acid. These form a fuzzy layer of unknown structure and function. It has become increasingly clear that the ESL-GC complex must play many roles. We postulate it has a self-organised infrastructure that directs cell traffic, acts in defence against pathogens and other cells, and in diseases like diabetes, and heart disease, besides being a playground for a host of biochemical activity. Based on an analogous sulphated polymeric system Nafion, the fuel cell polymer, we suggest a model for the structure of the ESL-GC complex and how it functions. Taken together with parallel developments in physical chemistry, in nanobubbles, their stability in physiological media, and reactivity, we believe the model may throw light on a variety of phenomena, diabetes and some other diseases.

The emerging role of glycans and the importance of sialylation in cardiovascular disease

Glycosylation is the process by which glycans (i.e. 'sugars') are enzymatically attached to proteins or lipids to form glycoconjugates. Growing evidence points to glycosylation playing a central role in atherosclerosis. Glycosylation occurs in all human cells and post-translationally modifies many signalling molecules that regulate cardiovascular disease, affecting their binding and function. Glycoconjugates are present in abundance on the vascular endothelium and on circulating lipoproteins, both of which have well-established roles in atherosclerotic plaque development. Sialic acid is a major regulator of glycan function and therefore the process of sialylation, in which sialic acid is added to glycans, is likely to be entwined in any regulation of atherosclerosis. Glycans and sialylation regulators have the potential to present as new biomarkers that predict atherosclerotic disease or as targets for pharmacological intervention, as well as providing insights into novel cardiovascular mechanisms. Moreover, the asialoglycoprotein receptor 1 (ASGR1), a glycan receptor, is emerging as an exciting new regulator of lipid metabolism and coronary artery disease. This review summarises the latest advances in the growing body of evidence that supports an important role for glycosylation and sialylation in the regulation of atherosclerosis.

Neutrophils and NETs in kidney disease

Neutrophils, conventionally regarded as a homogeneous immune cell population, have emerged as a heterogeneous group of cells with distinct gene profiles and immune properties. Activated neutrophils release a spectrum of bioactive substances, including cytokines, chemokines, proteolytic enzymes, reactive oxygen species and neutrophil extracellular traps (NETs), which are composed of decondensed DNA and antimicrobial proteins. NETs have a pivotal role in innate immunity, including in preventing the ascent of uropathogenic bacteria into the kidneys, as they efficiently trap pathogenic microorganisms. However, although indispensable for defence against pathogens, NETs also pose risks of self-damage owing to their cytotoxicity, thrombogenicity and autoantigenicity. Accordingly, neutrophils and NETs have been implicated in the pathogenesis of various disorders that affect the kidneys, including acute kidney injury, vasculitis, systemic lupus erythematosus, thrombotic microangiopathy and in various aetiologies of chronic kidney disease. Pathological alterations in the glomerular vascular wall can promote the infiltration of neutrophils, which can cause tissue damage and inflammation through their interactions with kidney-resident cells, including mesangial cells and podocytes, leading to local cell death. Targeting neutrophil activation and NET formation might therefore represent a new therapeutic strategy for these conditions.

Mineralocorticoid receptor blockage in kidney transplantation: too much of a good thing or not?

Although, kidney transplantation (KT) is the best treatment option for patients with end-stage kidney disease, long-term complications including chronic kidney allograft disease (CKAD) and major adverse cardiovascular events (MACE) are common. To decrease these complications new therapeutic options are necessary. Mineralocorticoid receptor antagonists (MRAs) are one of the promising drugs in this context. In the general population, MRAs had favorable effects on blood pressure regulation, MACE, proteinuria and progression of chronic kidney disease. In the context of KT, there are limited studies showing beneficial effects such as reducing proteinuria and oxidative stress. In this review, we performed a narrative review to assess the use and impact of MRAs in kidney transplant recipients. We found that in KTRs, MRAs are safe and they have favorable or neutral impact on blood pressure, glomerular filtration rate, urinary protein/albumin excretion, and oxidative stress. No data was found regarding major cardiovascular adverse events.

Multiplexed Lectin-PAINT super-resolution microscopy enables cell glycotyping

Glycosylation profoundly influences cellular function, yet deciphering its intricate patterns remains a formidable challenge. Current techniques often compromise sensitivity, multiplexing, or the ability to capture in-situ cell-to-cell variations. To address these limitations, we introduce 'Lectin-PAINT,' a super-resolution imaging method enabling multiplexed live-cell visualization of the cellular glycocalyx at the single-cell and single-molecule levels. Lectin-PAINT leverages the reversible binding of lectins to specific carbohydrate families to perform point accumulation in nanoscale topography (PAINT), enabling the identification, mapping, and tracking of carbohydrates with a resolution beyond the diffraction limit. Our technique harnesses a tailored lectin library, spanning key carbohydrate recognition, offering insights into their abundance, affinity, and mobility. Through 8-color super-resolution imaging, we extract more than 350 glycosylation parameters with single-cell resolution, creating a cell's 'glycotype' or glycan fingerprint. We showcase the power of this approach by glycotyping and categorizing a diverse set of cancer cell types, shedding light on the heterogeneity and variability of the glycocalyx in cancer. In the future, this research will contribute to the more fundamental understanding of changes in the glycocalyx due to disease.

Permeability Benchmarking: Guidelines for Comparing in Silico, in Vitro, and in Vivo Measurements

Permeability is a measure of the degree to which cells can transport molecules across biological barriers. Units of permeability are distance per unit time (typically cm/s), where accurate measurements are needed to define drug delivery in homeostasis and to model dysfunction occurring during disease. This perspective offers a set of community-led guidelines to benchmark permeability data across multidisciplinary approaches and different biological contexts. First, we lay out the analytical framework for three methodologies to calculate permeability: in silico assays using either transition-based counting or the inhomogeneous-solubility diffusion approaches, in vitro permeability assays using cells cultured in 2D or 3D geometries, and in vivo assays utilizing in situ brain perfusion or multiple time-point regression analysis. Then, we demonstrate a systematic benchmarking of in silico to both in vitro and in vivo, depicting the ways in which each benchmarking is sensitive to the choices of assay design. Finally, we outline seven recommendations for best practices in permeability benchmarking and underscore the significance of tailored permeability assays in driving advancements in drug delivery research and development. Our exploration encompasses a discussion of "generic" and tissue-specific biological barriers, including the blood-brain barrier (BBB), which is a major hurdle for the delivery of therapeutic agents into the brain. By addressing challenges in reconciling simulated data with experimental assays, we aim to provide insights essential for optimizing accuracy and reliability in permeability modeling.

The Mycobacterium ulcerans toxin mycolactone causes destructive Sec61-dependent loss of the endothelial glycocalyx and vessel basement membrane to drive skin necrosis

The drivers of tissue necrosis in Mycobacterium ulcerans infection (Buruli ulcer disease) have historically been ascribed solely to the directly cytotoxic action of the diffusible exotoxin, mycolactone. However, its role in the clinically evident vascular component of disease aetiology remains poorly explained. We have now dissected mycolactone's effects on human primary vascular endothelial cells in vitro. We show that mycolactone-induced changes in endothelial morphology, adhesion, migration, and permeability are dependent on its action at the Sec61 translocon. Unbiased quantitative proteomics identified a profound effect on proteoglycans, driven by rapid loss of type II transmembrane proteins of the Golgi, including enzymes required for glycosaminoglycan (GAG) synthesis, combined with a reduction in the core proteins themselves. Loss of the glycocalyx is likely to be of particular mechanistic importance, since knockdown of galactosyltransferase II (beta-1,3-galactotransferase 6; B3GALT6), the GAG linker-building enzyme, phenocopied the permeability and phenotypic changes induced by mycolactone. Additionally, mycolactone depleted many secreted basement membrane components and microvascular basement membranes were disrupted in vivo during M. ulcerans infection in the mouse model. Remarkably, exogenous addition of laminin-511 reduced endothelial cell rounding, restored cell attachment and reversed the defective migration caused by mycolactone. Hence supplementing mycolactone-depleted extracellular matrix may be a future therapeutic avenue, to improve wound healing rates.

Hydrogen sulfide alleviates endothelial glycocalyx damage and promotes placental angiogenesis in rats exposed to cigarette smoke

Our previous study has shown that hydrogen sulfide (H2S) can attenuate cigarette smoke exposure (CSE)-induced placental injury in rats. This study investigated whether H2S alleviates CSE-induced endothelial glycocalyx (eGC) impairment and promotes placental angiogenesis in rats. Twenty-four pregnant rats were randomly divided into four groups: control, NaHS (a donor of H2S), CSE, and CSE + NaHS. On gestational day 21, rat placentas were collected to detect H2S levels and protein expression of the H2S-synthesizing enzymes, cystathionine beta synthase (CBS), cystathionine gamma-lyase (CGL), and 3-mercaptopyruvate sulfurtransferase (3-MST), using a C-7Az fluorescent probe, H2S testing kit, and western blotting, respectively. Transmission electron microscopy and double immunofluorescence staining were performed to observe the placental eGC alterations. Placental angiogenesis, vascular endothelial proliferation and apoptosis, and protein expression levels of the PI3K/AKT/mTOR signaling pathway were assessed in rat placentas. The results showed that the administration of NaHS markedly attenuated the reduction in H2S levels and the decrease in CBS, CGL, and 3-MST expression caused by CSE in rat placentas. Notably, NaHS treatment distinctly alleviated eGC damage and facilitated placental angiogenesis in CSE-treated rats. NaHS administration effectively promoted placental vascular endothelial proliferation and suppressed endothelial apoptosis in CSE-treated rats. Furthermore, NaHS treatment markedly elevated the phosphorylation of PI3K, AKT, and mTOR in the placenta of CSE-treated rats. Taken together, these results indicate that exogenous administration of H2S can alleviate CSE-induced eGC damage and promote placental angiogenesis in CSE-treated rats, suggesting that H2S may be a novel therapeutic agent for the treatment of CSE-associated vascular disease.

Endothelial Dysfunction and Cardiovascular Disease: Hyperbaric Oxygen Therapy as an Emerging Therapeutic Modality?

Maintaining the physiological function of the vascular endothelium and endothelial glycocalyx is crucial for the prevention of cardiovascular disease, which is one of the leading causes of morbidity and mortality worldwide. Damage to these structures can lead to atherosclerosis, hypertension, and other cardiovascular problems, especially in individuals with risk factors such as diabetes and obesity. Endothelial dysfunction is associated with ischemic disease and has a negative impact on overall cardiovascular health. The aim of this review was to comprehensively summarize the crucial role of the vascular endothelium and glycocalyx in cardiovascular health and associated thrombo-inflammatory conditions. It highlights how endothelial dysfunction, influenced by factors such as diabetes, chronic kidney disease, and obesity, leads to adverse cardiovascular outcomes, including heart failure. Recent evidence suggests that hyperbaric oxygen therapy (HBOT) may offer therapeutic benefits in the treatment of cardiovascular risk factors and disease. This review presents the current evidence on the mechanisms by which HBOT promotes angiogenesis, shows antimicrobial and immunomodulatory effects, enhances antioxidant defenses, and stimulates stem cell activity. The latest findings on important topics will be presented, including the effects of HBOT on endothelial dysfunction, cardiac function, atherosclerosis, plaque stability, and endothelial integrity. In addition, the role of HBOT in alleviating cardiovascular risk factors such as hypertension, aging, obesity, and glucose metabolism regulation is discussed, along with its impact on inflammation in cardiovascular disease and its potential benefit in ischemia-reperfusion injury. While HBOT demonstrates significant therapeutic potential, the review also addresses potential risks associated with excessive oxidative stress and oxygen toxicity. By combining information on the molecular mechanisms of HBOT and its effects on the maintenance of vascular homeostasis, this review provides valuable insights into the development of innovative therapeutic strategies aimed at protecting and restoring endothelial function to prevent and treat cardiovascular diseases.

Mycolactone causes destructive Sec61-dependent loss of the endothelial glycocalyx and vessel basement membrane: a new indirect mechanism driving tissue necrosis in Mycobacterium ulcerans infection

The drivers of tissue necrosis in Mycobacterium ulcerans infection (Buruli ulcer disease) have historically been ascribed solely to the directly cytotoxic action of the diffusible exotoxin, mycolactone. However, its role in the clinically-evident vascular component of disease aetiology remains poorly explained. We have now dissected mycolactone's effects on primary vascular endothelial cells in vitro and in vivo. We show that mycolactone-induced changes in endothelial morphology, adhesion, migration, and permeability are dependent on its action at the Sec61 translocon. Unbiased quantitative proteomics identified a profound effect on proteoglycans, driven by rapid loss of type II transmembrane proteins of the Golgi, including enzymes required for glycosaminoglycan (GAG) synthesis, combined with a reduction in the core proteins themselves. Loss of the glycocalyx is likely to be of particular mechanistic importance, since knockdown of galactosyltransferase II (beta-1,3-galactotransferase 6; B3GALT6), the GAG linker-building enzyme, phenocopied the permeability and phenotypic changes induced by mycolactone. Additionally, mycolactone depleted many secreted basement membrane components and microvascular basement membranes were disrupted in vivo. Remarkably, exogenous addition of laminin-511 reduced endothelial cell rounding, restored cell attachment and reversed the defective migration caused by mycolactone. Hence supplementing mycolactone-depleted extracellular matrix may be a future therapeutic avenue, to improve wound healing rates.

Endothelial glycocalyx degradation in critically ill foals

BACKGROUND

Endothelial glycocalyx (EG) degradation occurs in septic humans and EG products can be used as biomarkers of endothelial injury. Information about EG biomarkers and their association with disease severity is lacking in hospitalized foals.

OBJECTIVES

Measure serum syndecan-1 (SDC-1), heparan sulfate (HS), angiopoietin-2 (ANG-2), aldosterone (ALD), and plasma atrial natriuretic peptide (ANP) concentrations and to determine their association with disease severity and death in hospitalized foals.

ANIMALS

Ninety foals ≤3 days old.

METHODS

Prospective, multicenter, longitudinal study. Foals were categorized into hospitalized (n = 74; 55 septic; 19 sick nonseptic) and 16 healthy foals. Serum ([SDC-1], [HS], [ANG-2], [ALD]) and plasma (ANP) were measured over 72 hours using immunoassays.

RESULTS

Serum ([SDC-1], [HS], [ANG-2], [ALD]) and plasma (ANP) were significantly higher in hospitalized and septic than healthy foals (P < .05). Serum (ANG-2) and plasma (ANP) were significantly higher in hospitalized nonsurvivors than in survivors (P < .05). On admission, hospitalized foals with serum (HS) > 58.7 ng/mL had higher odds of nonsurvival (odds ratio [OR] = 6.1; 95% confidence interval [CI] = 1.02-36.7). Plasma (ANP) >11.5 pg/mL was associated with the likelihood of nonsurvival in hospitalized foals (OR = 7.2; 95% CI = 1.4-37.4; P < .05). Septic foals with serum (ANG-2) >1018 pg/mL on admission had higher odds of nonsurvival (OR = 6.5; 95% CI =1.2-36.6; P < .05).

CONCLUSION AND CLINICAL IMPORTANCE

Critical illness in newborn foals is associated with EG degradation and injury, and these biomarkers are related to the severity of disease on admission and the outcome of sick foals.

Syndecan 4 is a marker of endothelial inflammation in pathological aging and predicts long-term cardiovascular outcomes in type 2 diabetes

BACKGROUND

Endothelial cellular senescence is emerging as a key mechanism of age-related vascular dysfunction. Disruption of the endothelium glycocalyx and shedding of the syndecan (SDC) ectodomains have been associated with several age-related diseases. Although SDC4 is highly expressed in endothelial cells, its levels and shedding in senescent endothelial cells and vascular endothelial dysfunction associated with aging are still unknown.

METHODS

To assess whether SDC4 expression was affected by inflammatory conditions, we evaluated its levels in young human umbilical vein endothelial cells (HUVECs) treated with TNF-α at a concentration of 50 ng/mL for 24 h and in cells undergoing replicative senescence. Plasma levels of SDC4 were evaluated in two previously recruited cohorts of (i) subjects with type 2 diabetes (T2D, n = 110) followed for a median of 16.8 years and age- and gender-matched healthy subjects (n = 100), and (ii) middle-aged subjects with mild-to-moderate dyslipidemia. Binomial logistic regression was used to assess whether SDC4 levels could be prognostic for major adverse cardiovascular events (MACE).

RESULTS

In the in vitro study, we showed that HUVECs, when exposed to TNF-α or undergoing replicative senescence, exhibited elevated expression levels of SDC4 and matrix metallopeptidase 9 (MMP-9), as well as increased shedding of SDC4 into the extracellular microenvironment, in comparison to actively proliferating young HUVECs. Analysis of human samples revealed that patients with T2D without complications exhibited higher SDC4 levels compared to healthy controls and those with T2D vascular complications. In particular, patients with a history of major adverse cardiovascular events (MACE) had lower SDC4 levels. The longitudinal evaluation revealed that higher SDC4 levels predict the onset of new MACE during a 16.8-year follow-up. In the second cohort, no significant association was observed between SDC4 and endothelial dysfunction, assessed by flow-mediated dilation (FMD) or nitric oxide metabolites. SDC4 levels correlated positively with C-reactive protein (CRP) in both cohorts and with PAI-1 in the cohort of patients with T2D.

CONCLUSION

Overall, we conclude that the shedding of SDC4 from endothelial cells increases under acute (TNF-α treatment) and chronic (senescence) inflammatory conditions and that increased circulating SDC4 levels are associated with systemic inflammation in pathological aging.

Cascading renal injury after brain death: Unveiling glycocalyx alteration and the potential protective role of tacrolimus

Brain death (BD) is a complex medical state that triggers systemic disturbances and a cascade of pathophysiological processes. This condition significantly impairs both kidney function and structural integrity, thereby presenting considerable challenges to graft viability and the long-term success of transplantation endeavors. Tacrolimus (FK506), an immunosuppressive drug, was used in this study to assess its impact as a pretreatment on brain death-induced renal injury. This study aimed to investigate changes associated with brain death-induced renal injury in a 4-month-old female porcine model. The experimental groups included brain death placebo-pretreated (BD; n = 9), brain death tacrolimus-pretreated using the clinical dose of 0.25 mg/kg the day before surgery, followed by 0.05 mg/kg/day 1 hour before the procedure (BD + FK506; n = 8), and control (ctrl, n = 7) piglets, which did not undergo brain death induction. Furthermore, we aimed to assess the effect of FK506 on these renal alterations through graft preconditioning. We hypothesized that immunosuppressive properties of FK506 reduce tissue inflammation and preserve the glycocalyx. Our findings revealed a series of interconnected events triggered by BD, leading to a deterioration of renal function and increased proteinuria, increased apoptosis in the vessels, glomeruli and tubules, significant leukocyte infiltration into renal tissue, and degradation of the glycocalyx in comparison with ctrl group. Importantly, treatment with FK506 demonstrated significant efficacy in attenuating these adverse effects. FK506 helped reduce apoptosis, maintain glycocalyx integrity, regulate neutrophil infiltration, and mitigate renal injury following BD. This study offers new insights into the pathophysiology of BD-induced renal injury, emphasizing the potential of FK506 pretreatment as a promising therapeutic intervention for organ preservation, through maintaining endothelial function with the additional benefit of limiting the risk of rejection.

The Effect of 4-Month Treatment with Glycocalyx Dietary Supplement on Endothelial Glycocalyx Integrity and Vascular Function in Patients with Psoriasis

Psoriasis predisposes to cardiovascular dysfunction. We investigated whether glycocalyx dietary supplement (GDS), which contains glycosaminoglycans and fucoidan, improves endothelial glycocalyx and arterial stiffness in psoriatic patients. Fifty participants with psoriasis under biological agents were randomly assigned to GDS (n = 25) or placebo (n = 25) for 4 months. We measured at baseline and at follow-up: (a) perfused boundary region (PBR) of the sublingual microvessels (range 4 to 25 μm), a marker of endothelium glycocalyx integrity; (b) carotid-femoral pulse wave velocity (PWV-Complior SP-ALAM) and augmentation index (AIx), markers of arterial stiffness and (c) psoriasis area and severity index (PASI) score. Both groups displayed a similar decrease in PASI at four months (p < 0.05), and no significant differences were found between groups (p > 0.05). Compared to the placebo, participants in the GDS showed a greater percentage reduction in PBR4-25 μm (-9.95% vs. -0.87%), PBR 4-9 μm (-6.50% vs. -0.82%), PBR10-19 μm (-5.12% vs. -1.60%), PBR 20-25 μm (-14.9% vs. -0.31%), PWV (-15.27% vs. -4.04%) and AIx (-35.57% vs. -21.85%) (p < 0.05). In the GDS group, the percentage reduction in PBR 4-25 μm was associated with the corresponding decrease in PWV (r = 0.411, p = 0.015) and AΙx (r = 0.481, p = 0.010) at follow-up. Four-month treatment with GDS improves glycocalyx integrity and arterial stiffness in patients with psoriasis. Clinical trial Identifier: NCT05184699.

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.

Trauma promotes heparan sulfate modifications and cleavage that disrupt homeostatic gene expression in microvascular endothelial cells

Introduction: Heparan sulfate (HS) in the vascular endothelial glycocalyx (eGC) is a critical regulator of blood vessel homeostasis. Trauma results in HS shedding from the eGC, but the impact of trauma on HS structural modifications that could influence mechanisms of vascular injury and repair has not been evaluated. Moreover, the effect of eGC HS shedding on endothelial cell (EC) homeostasis has not been fully elucidated. The objectives of this work were to characterize the impact of trauma on HS sulfation and determine the effect of eGC HS shedding on the transcriptional landscape of vascular ECs. Methods: Plasma was collected from 25 controls and 49 adults admitted to a level 1 trauma center at arrival and 24 h after hospitalization. Total levels of HS and angiopoietin-2, a marker of pathologic EC activation, were measured at each time point. Enzymatic activity of heparanase, the enzyme responsible for HS shedding, was determined in plasma from hospital arrival. Liquid chromatography-tandem mass spectrometry was used to characterize HS di-/tetrasaccharides in plasma. In vitro work was performed using flow conditioned primary human lung microvascular ECs treated with vehicle or heparinase III to simulate human heparanase activity. Bulk RNA sequencing was performed to determine differentially expressed gene-enriched pathways following heparinase III treatment. Results: We found that heparanase activity was increased in trauma plasma relative to controls, and HS levels at arrival were elevated in a manner proportional to injury severity. Di-/tetrasaccharide analysis revealed lower levels of 3-O-sulfated tetramers with a concomitant increase in ΔIIIS and ΔIIS disaccharides following trauma. Admission levels of total HS and specific HS sulfation motifs correlated with 24-h angiopoietin-2 levels, suggesting an association between HS shedding and persistent, pathological EC activation. In vitro pathway analysis demonstrated downregulation of genes that support cell junction integrity, EC polarity, and EC senescence while upregulating genes that promote cell differentiation and proliferation following HS shedding. Discussion: Taken together, our findings suggest that HS cleavage associated with eGC injury may disrupt homeostatic EC signaling and influence biosynthetic mechanisms governing eGC repair. These results require validation in larger, multicenter trauma populations coupled with in vivo EC-targeted transcriptomic and proteomic analyses.

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.

Clinical evidence and rationale of mesoglycan to treat chronic venous disease and hemorrhoidal disease: a narrative review

Chronic venous disease (CVD) and hemorrhoidal disease (HD) are among the most common vascular diseases in the world, with CVD affecting 22-41% of the population in Europe and HD having a point prevalence of 11-39%. The burden is substantial in terms of the effect of symptoms on patients' health-related quality of life (HRQoL) and direct/indirect medical costs. Treatment begins with lifestyle changes, compression in CVD and topical therapies in HD, and escalates as needed through oral therapies first and eventually to surgery for severe disease. CVD and HD share etiological features and pathological changes affecting the structure and function of the tissue extracellular matrix. Mesoglycan, a natural glycosaminoglycan (GAG) preparation composed primarily of heparan sulfate and dermatan sulfate, has been demonstrated to positively impact the underlying causes of CVD and HD, regenerating the glycocalyx and restoring endothelial function, in addition to having antithrombotic, profibrinolytic, anti-inflammatory, antiedema and wound-healing effects. In clinical trials, oral mesoglycan reduced the severity of CVD signs and symptoms, improved HRQoL, and accelerated ulcer healing. In patients with HD, mesoglycan significantly reduced the severity of signs and symptoms and the risk of rectal bleeding. In patients undergoing excisional hemorrhoidectomy, adding mesoglycan to standard postoperative care reduced pain, improved HRQoL, reduced incidence of thrombosis, and facilitated an earlier return to normal activities/work, compared with standard postoperative care alone. The clinical effects of mesoglycan in patients with CVD or HD are consistent with the agent's known mechanisms of action.

Recent Developments and Application of Mass Spectrometry Imaging in N-Glycosylation Studies: An Overview

Among the most typical posttranslational modifications is glycosylation, which often involves the covalent binding of an oligosaccharide (glycan) to either an asparagine (N-linked) or a serine/threonine (O-linked) residue. Studies imply that the N-glycan portion of a glycoprotein could serve as a particular disease biomarker rather than the protein itself because N-linked glycans have been widely recognized to evolve with the advancement of tumors and other diseases. N-glycans found on protein asparagine sites have been especially significant. Since N-glycans play clearly defined functions in the folding of proteins, cellular transport, and transmission of signals, modifications to them have been linked to several illnesses. However, because these N-glycans' production is not template driven, they have a substantial morphological range, rendering it difficult to distinguish the species that are most relevant to biology and medicine using standard techniques. Mass spectrometry (MS) techniques have emerged as effective analytical tools for investigating the role of glycosylation in health and illness. This is due to developments in MS equipment, data collection, and sample handling techniques. By recording the spatial dimension of a glycan's distribution in situ, mass spectrometry imaging (MSI) builds atop existing methods while offering added knowledge concerning the structure and functionality of biomolecules. In this review article, we address the current development of glycan MSI, starting with the most used tissue imaging techniques and ionization sources before proceeding on to a discussion on applications and concluding with implications for clinical research.

Prevention of vincristine-induced peripheral neuropathy by protecting the endothelial glycocalyx shedding

Vincristine-induced peripheral neuropathy (VIPN) adversely affects the quality of life and treatment continuity of patients. The endothelial glycocalyx (eGCX) protects nerves from harmful substances released from the capillary vessels, but its role in peripheral neuropathy remains unclear. We investigated the impact of eGCX protection on VIPN. Using a murine model of VIPN, we administered nafamostat mesylate to protect the eGCX shedding, and analyzed the eGCX integrity and manifestation of peripheral neuropathy. Nafamostat treatment suppressed allodynia associated with neuropathy. Additionally, nafamostat administration resulted in the suppression of increased vascular permeability in capillaries of peripheral nerves, further indicating its positive influence on eGCX in VIPN model mice. This study provided the importance of eGCX in VIPN. With the potential for rapid clinical translation through drug repositioning, nafamostat may be a new promising treatment for the prevention of VIPN.

The impact of vascular endothelial glycocalyx on the pathogenesis and treatment of disseminated intravascular coagulation

Disseminated intravascular coagulation (DIC) is a complex disorder characterized by widespread activation of blood clotting mechanisms throughout the body. Understanding the role of vascular endothelial glycocalyx in the pathogenesis and treatment of DIC is crucial for advancing our knowledge in this field. The vascular endothelial glycocalyx is a gel-like layer that coats the inner surface of blood vessels. It plays a significant role in maintaining vascular integrity, regulating fluid balance, and preventing excessive clotting. In the pathogenesis of DIC, the disruption of the vascular endothelial glycocalyx is a key factor. Pathological conditions trigger the activation of enzymes, including heparanase, hyaluronase, and matrix metalloproteinase. This activation leads to glycocalyx degradation, subsequently exposing endothelial cells to procoagulant stimuli. Additionally, the ANGPTs/Tie-2 signaling pathway plays a role in the imbalance between the synthesis and degradation of VEG, exacerbating endothelial dysfunction and DIC. Understanding the mechanisms behind glycocalyx degradation and its impact on DIC can provide valuable insights for the development of targeted therapies. Preservation of the glycocalyx integrity may help prevent the initiation and propagation of DIC. Strategies such as administration of exogenous glycocalyx components, anticoagulant agents, or Tie-2 antibody agents have shown promising results in experimental models. In conclusion, the vascular endothelial glycocalyx plays a crucial role in the pathogenesis and treatment of DIC. Further research in this field is warranted to unravel the complex interactions between the glycocalyx and DIC, ultimately leading to the development of novel therapies.

The role of glycosaminoglycans in blood pressure regulation

Essential hypertension (HT) is the global health problem and is a major risk factor for the development of cardiovascular and kidney disease. High salt intake has been associated with HT and impaired kidney sodium excretion is considered to be a major mechanism for the development of HT. Although kidney has a very important role in regulation of BP, this traditional view of BP regulation was challenged by recent findings suggesting that nonosmotic tissue sodium deposition is very important for BP regulation. This new paradigm indicates that sodium can be stored and deposited nonosmotically in the interstitium without water retention and without increased BP. One of the major determinants of this deposition is glycosaminoglycans (GAGs). By binding to GAGs found in the endothelial surface layer (ESL) which contains glycocalyx, sodium is osmotically inactivated and not induce concurrent water retention. Thus, GAGs has important function for homeostatic BP and sodium regulation. In the current review, we summarized the role of GAGs in ESL and BP regulation.

Plasma glycocalyx pattern: a mirror of endothelial damage in chronic kidney disease

Background

Endothelial damage and cardiovascular disease complicate chronic kidney disease (CKD). The increased atherogenicity observed in patients with CKD can be linked to microinflammation and endothelial damage. Circulating endothelial glycocalyx degradation products, such as perlecan and decorin, tend to be elevated in CKD. We aimed to explore the association between the plasma perlecan and decorin levels and this pro-inflammatory and atherogenic state by studying monocyte subpopulations and intracellular adhesion molecule (ICAM)-1 expression in patients with CKD.

Methods

We studied 17 healthy controls, 23 patients with advanced CKD, 25 patients on haemodialysis, 23 patients on peritoneal dialysis and 20 patients who underwent kidney transplantation. Perlecan and decorin levels were evaluated using enzyme-linked immunosorbent assays, and the monocyte phenotype was analysed using direct immunofluorescence and flow cytometry.

Results

The plasma perlecan levels were higher in patients with CKD than in the healthy controls. These levels were associated with a higher prevalence of ICAM-1+ monocytes. Conversely, patients with advanced CKD (pre-dialysis) had higher plasma decorin levels, which were associated with a reduced ICAM-1 expression per monocyte.

Conclusions

Elevated perlecan levels in CKD may be associated with a higher prevalence of ICAM-1+ monocytes and a pro-inflammatory phenotype. Elevated decorin levels may act as a negative regulator of ICAM-1 expression in monocytes. Therefore, perlecan and decorin may be related to inflammation and monocyte activation in CKD and may act as potential markers of endothelial damage.

Influence of the vessel wall geometry on the wall-induced migration of red blood cells

The geometry of the blood vessel wall plays a regulatory role on the motion of red blood cells (RBCs). The overall topography of the vessel wall depends on many features, among which the endothelial lining of the endothelial surface layer (ESL) is an important one. The endothelial lining of vessel walls presents a large surface area for exchanging materials between blood and tissues. The ESL plays a critical role in regulating vascular permeability, hindering leukocyte adhesion as well as inhibiting coagulation during inflammation. Changes in the ESL structure are believed to cause vascular hyperpermeability and entrap immune cells during sepsis, which could significantly alter the vessel wall geometry and disturb interactions between RBCs and the vessel wall, including the wall-induced migration of RBCs and the thickening of a cell-free layer. To investigate the influence of the vessel wall geometry particularly changed by the ESL under various pathological conditions, such as sepsis, on the motion of RBCs, we developed two models to represent the ESL using the immersed boundary method in two dimensions. In particular, we used simulations to study how the lift force and drag force on a RBC near the vessel wall vary with different wall thickness, spatial variation, and permeability associated with changes in the vessel wall geometry. We find that the spatial variation of the wall has a significant effect on the wall-induced migration of the RBC for a high permeability, and that the wall-induced migration is significantly inhibited as the vessel diameter is increased.

Syndecan-1 predicts hemodynamic instability in critically ill patients under intermittent hemodialysis

Introduction

Up to 70% of intermittent hemodialysis (IHD) sessions in critically ill patients are complicated by hemodynamic instability. Although several clinical characteristics have been associated with hemodynamic instability during IHD, the discriminatory capacity of predicting such events during IHD sessions is less defined. In the present study, we aimed to analyse endothelium-related biomarkers collected before IHD sessions and their capacity to predict hemodynamic instability related to IHD in critically ill patients.

Methods

In this prospective observational study, we enrolled adult critically ill patients with acute kidney injury who required fluid removal with IHD. We screened each included patient daily for IHD sessions. Thirty minutes before each IHD session, each patient had a 5-mL blood collection for measurement of endothelial biomarkers-vascular cell adhesion molecule-1 (VCAM-1), angiopoietin-1 and -2 (AGPT1 and AGPT2) and syndecan-1. Hemodynamic instability during IHD was the main outcome. Analyses were adjusted for variables already known to be associated with hemodynamic instability during IHD.

Results

Plasma syndecan-1 was the only endothelium-related biomarker independently associated with hemodynamic instability. The accuracy of syndecan-1 for predicting hemodynamic instability during IHD was moderate [area under the receiver operating characteristic curve 0.78 (95% confidence interval 0.68-0.89)]. The addition of syndecan-1 improved the discrimination capacity of a clinical model from 0.67 to 0.82 (P < .001) and improved risk prediction, as measured by net reclassification improvement.

Conclusion

Syndecan-1 is associated with hemodynamic instability during IHD in critically ill patients. It may be useful to identify patients who are at increased risk for such events and suggests that endothelial glycocalyx derangement is involved in the pathophysiology of IHD-related hemodynamic instability.

Expanding the Horizons of Pre-Transplant Renal Vascular Assessment Using Ex Vivo Perfusion

Recently, immense efforts have focused on improving the preservation of (sub)optimal donor organs by means of ex vivo perfusion, which enables the opportunity for organ reconditioning and viability assessment. However, there is still no biomarker that correlates with renal viability. Therefore, it is essential to explore new techniques for pre-transplant assessment of organ quality to guarantee successful long-term transplantation outcomes. The renal vascular compartment has received little attention in machine perfusion studies. In vivo, proper renal vascular and endothelial function is essential for maintaining homeostasis and long-term graft survival. In an ex vivo setting, little is known about vascular viability and its implications for an organ's suitability for transplant. Seeing that endothelial damage is the first step in a cascade of disruptions and maintaining homeostasis is crucial for positive post-transplant outcomes, further research is key to clarifying the (patho)physiology of the renal vasculature during machine perfusion. In this review, we aim to summarize key aspects of renal vascular physiology, describe the role of the renal vasculature in pathophysiological settings, and explain how ex vivo perfusion plays a role in either unveiling or targeting such processes. Additionally, we discuss potentially new vascular assessment tools during ex vivo renal perfusion.

Endothelial Glycocalyx Preservation-Impact of Nutrition and Lifestyle

The endothelial glycocalyx (eGC) is a dynamic hair-like layer expressed on the apical surface of endothelial cells throughout the vascular system. This layer serves as an endothelial cell gatekeeper by controlling the permeability and adhesion properties of endothelial cells, as well as by controlling vascular resistance through the mediation of vasodilation. Pathogenic destruction of the eGC could be linked to impaired vascular function, as well as several acute and chronic cardiovascular conditions. Defining the precise functions and mechanisms of the eGC is perhaps the limiting factor of the missing link in finding novel treatments for lifestyle-related diseases such as atherosclerosis, type 2 diabetes, hypertension, and metabolic syndrome. However, the relationship between diet, lifestyle, and the preservation of the eGC is an unexplored territory. This article provides an overview of the eGC's importance for health and disease and describes perspectives of nutritional therapy for the prevention of the eGC's pathogenic destruction. It is concluded that vitamin D and omega-3 fatty acid supplementation, as well as healthy dietary patterns such as the Mediterranean diet and the time management of eating, might show promise for preserving eGC health and, thus, the health of the cardiovascular system.

Endothelial Glycocalyx and Cardiomyocyte Damage Is Prevented by Recombinant Syndecan-1 in Acute Myocardial Infarction

The outer layer of endothelial cells (ECs), consisting of the endothelial glycocalyx (eGC) and the cortex (CTX), provides a protective barrier against vascular diseases. Structural and functional impairments of their mechanical properties are recognized as hallmarks of endothelial dysfunction and can lead to cardiovascular events, such as acute myocardial infarction (AMI). This study investigated the effects of AMI on endothelial nanomechanics and function and the use of exogenous recombinant syndecan-1 (rSyn-1), a major component of the eGC, as recovering agent. ECs were exposed in vitro to serum samples collected from patients with AMI. In addition, in situ ECs of ex vivo aorta preparations derived from a mouse model for AMI were employed. Effects were quantified by using atomic force microscopy-based nanoindentation measurements, fluorescence staining, and histologic examination of the mouse hearts. AMI serum samples damaged eGC/CTX and augmented monocyte adhesion to the endothelial surface. In particular, the anaphylatoxins C3a and C5a played an important role in these processes. The impairment of endothelial function could be prevented by rSyn-1 treatment. In the mouse model of myocardial infarction, pretreatment with rSyn-1 alleviated eGC/CTX deterioration and reduced cardiomyocyte damage in histologic analyses. However, echocardiographic measurements did not indicate a functional benefit. These results provide new insights into the underlying mechanisms of AMI-induced endothelial dysfunction and perspectives for future studies on the benefit of rSyn-1 in post-AMI treatment.

Effect of permeability on the initiation of Atherosclerosis modeled as an inflammatory process

This work presents a mathematical model, based on partial differential equations, that analyzes the inflammatory stage of atherosclerosis. Four leading players are taken into consideration: Low Density Lipoproteins, oxidized Low Density Lipoproteins, immune cells and the inflammatory cytokines. In addition to this, the permeability of the endothelial layer is taken into account in the model. A stability analysis of the fixed points of the kinetic system is presented in details followed by the proof of existence of traveling wave solutions of the system of partial differential equations. The mathematical analysis leads to a biological interpretation. We distinguish three main cases of the disease state that correlate with the permeability of the endothelial layer. In fact, having a low permeability indicates the disease free state since no chronic inflammatory reaction occurs due to the non initiation of the inflammation. With intermediate permeability, a wave propagation corresponding to a chronic inflammatory reaction might occur whether the initial perturbation overcomes a threshold or not. With high permeability, even a small perturbation of the disease free state leads to a chronic inflammatory reaction represented by a wave propagation. We perform numerical simulations of the solutions to illustrate the biological results.

Mineralocorticoid receptor antagonism in diabetes reduces albuminuria by preserving the glomerular endothelial glycocalyx

The glomerular endothelial glycocalyx (GEnGlx) forms the first part of the glomerular filtration barrier. Previously, we showed that mineralocorticoid receptor (MR) activation caused GEnGlx damage and albuminuria. In this study, we investigated whether MR antagonism could limit albuminuria in diabetes and studied the site of action. Streptozotocin-induced diabetic Wistar rats developed albuminuria, increased glomerular albumin permeability (Ps'alb), and increased glomerular matrix metalloproteinase (MMP) activity with corresponding GEnGlx loss. MR antagonism prevented albuminuria progression, restored Ps'alb, preserved GEnGlx, and reduced MMP activity. Enzymatic degradation of the GEnGlx negated the benefits of MR antagonism, confirming their dependence on GEnGlx integrity. Exposing human glomerular endothelial cells (GEnC) to diabetic conditions in vitro increased MMPs and caused glycocalyx damage. Amelioration of these effects confirmed a direct effect of MR antagonism on GEnC. To confirm relevance to human disease, we used a potentially novel confocal imaging method to show loss of GEnGlx in renal biopsy specimens from patients with diabetic nephropathy (DN). In addition, patients with DN randomized to receive an MR antagonist had reduced urinary MMP2 activity and albuminuria compared with placebo and baseline levels. Taken together, our work suggests that MR antagonists reduce MMP activity and thereby preserve GEnGlx, resulting in reduced glomerular permeability and albuminuria in diabetes.

Applications and continued evolution of glycan imaging mass spectrometry

Glycosylation is an important posttranslational modifier of proteins and lipid conjugates critical for the stability and function of these macromolecules. Particularly important are N-linked glycans attached to asparagine residues in proteins. N-glycans have well-defined roles in protein folding, cellular trafficking and signal transduction, and alterations to them are implicated in a variety of diseases. However, the non-template driven biosynthesis of these N-glycans leads to significant structural diversity, making it challenging to identify the most biologically and clinically relevant species using conventional analyses. Advances in mass spectrometry instrumentation and data acquisition, as well as in enzymatic and chemical sample preparation strategies, have positioned mass spectrometry approaches as powerful analytical tools for the characterization of glycosylation in health and disease. Imaging mass spectrometry expands upon these strategies by capturing the spatial component of a glycan's distribution in-situ, lending additional insight into the organization and function of these molecules. Herein we review the ongoing evolution of glycan imaging mass spectrometry beginning with widely adopted tissue imaging approaches and expanding to other matrices and sample types with potential research and clinical implications. Adaptations of these techniques, along with their applications to various states of disease, are discussed. Collectively, glycan imaging mass spectrometry analyses broaden our understanding of the biological and clinical relevance of N-glycosylation to human disease.

Human collecting lymphatic glycocalyx identification by electron microscopy and immunohistochemistry

Blood flow is translated into biochemical inflammatory or anti-inflammatory signals based onshear stress type, by means of sensitive endothelial receptors. Recognition of the phenomenon is of paramount importance for enhanced insights into the pathophysiological processes of vascular remodeling. The endothelial glycocalyx is a pericellular matrix, identified in both arteries and veins, acting collectively as a sensor responsive to blood flow changes. Venous and lymphatic physiology is interconnected; however, to our knowledge, a lymphatic glycocalyx structure has never been identified in humans. The objective of this investigation is to identify glycocalyx structures from ex vivo lymphatic human samples. Lower limb vein and lymphatic vessels were harvested. The samples were analyzed by transmission electron microscopy. The specimens were also examined by immunohistochemistry. Transmission electron microscopy identified a glycocalyx structure in human venous and lymphatic samples. Immunohistochemistry for podoplanin, glypican-1, mucin-2, agrin and brevican characterized lymphatic and venous glycocalyx-like structures. To our knowledge, the present work reports the first identification of a glycocalyx-like structure in human lymphatic tissue. The vasculoprotective action of the glycocalyx could become an investigational target in the lymphatic system as well, with clinical implications for the many patients affected by lymphatic disorders.

Modeling C3 glomerulopathies: C3 convertase regulation on an extracellular matrix surface

Introduction

C3 glomerulopathies (C3G) are ultra-rare complement-mediated diseases that lead to end-stage renal disease (ESRD) within 10 years of diagnosis in ~50% of patients. Overactivation of the alternative pathway (AP) of complement in the fluid phase and on the surface of the glomerular endothelial glycomatrix is the underlying cause of C3G. Although there are animal models for C3G that focus on genetic drivers of disease, in vivo studies of the impact of acquired drivers are not yet possible.

Methods

Here we present an in vitro model of AP activation and regulation on a glycomatrix surface. We use an extracellular matrix substitute (MaxGel) as a base upon which we reconstitute AP C3 convertase. We validated this method using properdin and Factor H (FH) and then assessed the effects of genetic and acquired drivers of C3G on C3 convertase.

Results

We show that C3 convertase readily forms on MaxGel and that this formation was positively regulated by properdin and negatively regulated by FH. Additionally, Factor B (FB) and FH mutants impaired complement regulation when compared to wild type counterparts. We also show the effects of C3 nephritic factors (C3Nefs) on convertase stability over time and provide evidence for a novel mechanism of C3Nef-mediated C3G pathogenesis.

Discussion

We conclude that this ECM-based model of C3G offers a replicable method by which to evaluate the variable activity of the complement system in C3G, thereby offering an improved understanding of the different factors driving this disease process.

Setting the stage for universal pharmacological targeting of the glycocalyx

All cells in the human body are covered by a complex meshwork of sugars as well as proteins and lipids to which these sugars are attached, collectively termed the glycocalyx. Over the past few decades, the glycocalyx has been implicated in a range of vital cellular processes in health and disease. Therefore, it has attracted considerable interest as a therapeutic target. Considering its omnipresence and its relevance for various areas of cell biology, the glycocalyx should be a versatile platform for therapeutic intervention, however, the full potential of the glycocalyx as therapeutic target is yet to unfold. This might be attributable to the fact that glycocalyx alterations are currently discussed mainly in the context of specific diseases. In this perspective review, we shift the attention away from a disease-centered view of the glycocalyx, focusing on changes in glycocalyx state. Furthermore, we survey important glycocalyx-targeted drugs currently available and finally discuss future steps. We hope that this approach will inspire a unified, holistic view of the glycocalyx in disease, helping to stimulate novel glycocalyx-targeted therapy strategies.

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.

Endothelial glycocalyx and microvascular perfusion are associated with carotid intima-media thickness and impaired myocardial deformation in psoriatic disease

Psoriatic disease is associated with vascular and myocardial dysfunction. We aimed to evaluate endothelial glycocalyx barrier properties and microvascular perfusion in psoriatic patients, as well as their correlation with carotid intima-media thickness (cIMT) and markers of left ventricular (LV) myocardial deformation. We examined 297 psoriatic patients and 150 controls, adjusted for age, sex, and atherosclerotic risk factors. The severity of psoriatic disease was estimated using the psoriasis area and severity index (PASI). Perfused boundary region (PBR), a marker of glycocalyx barrier function, was measured non-invasively in sublingual microvessels with a diameter 5-25 μm using Sidestream Dark Field camera (Microscan, GlycoCheck). Increased PBR indicates reduced glycocalyx thickness. Indexes of microvascular perfusion, including red blood cells filling (RBCF) and functional microvascular density, were also calculated. We measured cIMT, coronary flow reserve (CFR) and markers of myocardial deformation by speckle-tracking imaging, namely global longitudinal strain (GLS) and percentage changes between peak twisting and untwisting at mitral valve opening (%dpTw-Utw_MVO). Compared to controls, psoriatic patients had higher PBR_5-25μm (2.13 ± 0.29μm versus 1.78 ± 0.25μm, p < 0.001) and lower RBCF and functional microvascular density (p < 0.001). Increased PASI was associated with elevated PBR and more impaired cIMT and GLS (p < 0.05). There was an inverse association of PBR with RBCF and functional microvascular density (p < 0.001). In psoriatic population, increased PBR was related to increased cIMT, reduced CFR, impaired GLS and decreased %dpTw-Utw_MVO (p < 0.001). Glycocalyx thickness is reduced in psoriatic patients, which in turn impairs microvascular perfusion, and is associated with carotid IMT and impaired coronary and myocardial function.Clinical Trial Registration-URL: http://www.clinicaltrials.gov . Unique identifier: NCT02144857.

Isolation of Conditionally Immortalized Mouse Glomerular Endothelial Cells with Fluorescent Mitochondria

Glomerular endothelial cell (GEC) dysfunction can initiate and contribute to glomerular filtration barrier breakdown. Increased mitochondrial oxidative stress has been suggested as a mechanism resulting in GEC dysfunction in the pathogenesis of some glomerular diseases. Historically the isolation of GECs from in vivo models has been notoriously challenging due to difficulties in isolating pure cultures from glomeruli. GECs have complex growth requirements in vitro and a very limited lifespan. Here, we describe the procedure for isolating and culturing conditionally immortalized GECs with fluorescent mitochondria, enabling the tracking of mitochondrial fission and fusion events. GECs were isolated from the kidneys of a double transgenic mouse expressing the thermolabile SV40 TAg (from the Immortomouse), conditionally promoting proliferation and suppressing cell differentiation, and a photo-convertible fluorescent protein (Dendra2) in all mitochondria (from the photo-activatable mitochondria [PhAMexcised] mouse). The stable cell line generated allows for cell differentiation after inactivation of the immortalizing SV40 TAg gene and photo-activation of a subset of mitochondria causing a switch in fluorescence from green to red. The use of mitoDendra2-GECs allows for live imaging of fluorescent mitochondria's distribution, fusion, and fission events without staining the cells.

Arterial hypertension as a consequence of endothelial glycocalyx dysfunction: a modern view of the problem of cardiovascular diseases

Arterial hypertension (AH) is a leading risk factor for the development of cardiovascular, cerebrovascular, and renal diseases, which are among the top 10 most common causes of death in the world. The etiology of hypertension has not been fully elucidated, but it has been established that endothelial dysfunction is the most significant pathogenetic link in the formation and progression of the disease. The data obtained in the last 10-15 years on endothelial glycocalyx (eGC) studies indicate that endothelial dysfunction is preceded 

by destabilization and shedding of eGC with the appearance of its soluble components in the blood, which is equivalent to a process that can be designated as eGC dysfunction. Signs of eGC dysfunction are expressed in the development of hypertension, diseases of the cardiovascular system, and their complications. The purpose of this review is to analyze and substantiate the pathophysiological role of eGC dysfunction in hypertension and cardiovascular diseases and to describe approaches for its assessment and pharmacological correction. Abstracts and full-size articles of 425 publications in Pubmed/MEDLINE databases over 20 years were studied. The review discusses the role of eGC in the regulation of vascular tone, endothelial barrier function, and anti-adhesive properties of eGC. Modifications of eGC under the influence of pro-inflammatory stimuli, changes in eGC with age, and with increased salt load are considered. The aspect associated with eGC dysfunction in atherosclerosis, hyperglycemia and hypertension is covered. Assessment of eGC dysfunction is difficult but can be performed by indirect methods, in particular by detecting eGC components in blood. A brief description of the main approaches to pharmacoprevention and pharmacocorrection of hypertension is given from the position of exposure effects on eGC, which currently has more a fundamental than practical orientation. This opens up great opportunities for clinical studies of eGC dysfunction for the prevention and treatment of hypertension and justifies a new direction in the clinical pharmacology of antihypertensive drugs.

The VEGF Inhibitor Soluble Fms-like Tyrosine Kinase 1 Does Not Promote AKI-to-CKD Transition

(1) Background: Soluble Fms-like tyrosine kinase 1 (sFLT1) is an endogenous VEGF inhibitor. sFLT1 has been described as an anti-inflammatory treatment for diabetic nephropathy and heart fibrosis. However, sFLT1 has also been related to peritubular capillary (PTC) loss, which promotes fibrogenesis. Here, we studied whether transfection with sFlt1 aggravates experimental AKI-to-CKD transition and whether sFLT1 is increased in human kidney fibrosis. (2) Methods: Mice were transfected via electroporation with sFlt1. After confirming transfection efficacy, mice underwent unilateral ischemia/reperfusion injury (IRI) and were sacrificed 28 days later. Kidney histology and RNA were analyzed to study renal fibrosis, PTC damage and inflammation. Renal sFLT1 mRNA expression was measured in CKD biopsies and control kidney tissue. (3) Results: sFlt1 transfection did not aggravate renal fibrosis, PTC loss or macrophage recruitment in IRI mice. In contrast, higher transfection efficiency was correlated with reduced expression of pro-fibrotic and pro-inflammatory markers. In the human samples, sFLT1 mRNA levels were similar in CKD and control kidneys and were not correlated with interstitial fibrosis or PTC loss. (4) Conclusion: As we previously found that sFLT1 has therapeutic potential in diabetic nephropathy, our findings indicate that sFLT1 can be administered at a dose that is therapeutically effective in reducing inflammation, without promoting maladaptive kidney damage.

Glycosylated gold nanoparticles in point of care diagnostics: from aggregation to lateral flow

Current point-of-care lateral flow immunoassays, such as the home pregnancy test, rely on proteins as detection units (e.g. antibodies) to sense for analytes. Glycans play a fundamental role in biological signalling and recognition events such as pathogen adhesion and hence they are promising future alternatives to antibody-based biosensing and diagnostics. Here we introduce the potential of glycans coupled to gold nanoparticles as recognition agents for lateral flow diagnostics. We first introduce the concept of lateral flow, including a case study of lateral flow use in the field compared to other diagnostic tools. We then introduce glycosylated materials, the affinity gains achieved by the cluster glycoside effect and the current use of these in aggregation based assays. Finally, the potential role of glycans in lateral flow are explained, and examples of their successful use given.

Antibody-based lateral flow (immune) assays are well established, but here the emerging concept and potential of using glycans as the detection agents is reviewed.

Pleiotropic effects of SGLT2 inhibitors and heart failure outcomes

Heart failure (HF) represents a major public health concern with increasing prevalence among aging populations, with multifactorial pathophysiology including inflammation, oxidative stress, endothelial dysfunction, and fibrosis, among others. Lately, the use of sodium-glucose cotransporter-2 (SGLT2) inhibitors, originally destined for the treatment of type 2 diabetes mellitus, have revolutionized the treatment of HF. In this review article, we provide the milestones and the latest mechanistic evidence of SGLT2 inhibition in HF. Owing to the results of experimental studies, several pleiotropic effects of SGLT2 inhibitors have been proposed, including the restoration of autophagy which may be significant in the reversal of the aforementioned HF pathophysiology according to a latest hypotheses. Additional mechanisms consist of the regulation of inflammatory, oxidative, and fibrotic pathways, together with the improvement of endothelial function and reduction of epicardial adipose tissue. Other than their role as antidiabetic agents, a reduction in heart failure hospitalizations has been noted following their use in clinical trials, irrespective of DM status and degree of systolic dysfunction. Upcoming randomized trials are expected to additional clinical and mechanistic evidence regarding the diverse effects of SGLT2 inhibition across the spectrum of heart failure.

P-selectin mobility undergoes a sol-gel transition as it diffuses from exocytosis sites into the cell membrane

In response to vascular damage, P-selectin molecules are secreted onto the surface of cells that line our blood vessels. They then serve as mechanical anchors to capture leucocytes from the blood stream. Here, we track individual P-selectin molecules released at the surface of live endothelial cells following stimulated secretion. We find P-selectin initially shows fast, unrestricted diffusion but within a few minutes, movement becomes increasingly restricted and ~50% of the molecules become completely immobile; a process similar to a sol-gel transition. We find removal of the extracellular C-type lectin domain (ΔCTLD) and/or intracellular cytoplasmic tail domain (ΔCT) has additive effects on diffusive motion while disruption of the adapter complex, AP2, or removal of cell-surface heparan sulphate restores mobility of full-length P-selectin close to that of ΔCT and ΔCTLD respectively. We have found P-selectin spreads rapidly from sites of exocytosis and evenly decorates the cell surface, but then becomes less mobile and better-suited to its mechanical anchoring function.

P-selectin recruits leucocytes to regions of blood vessel damage. Using single molecule imaging, we find newly secreted P-selectin spreads rapidly across the plasma membrane and then becomes immobilized and better-suited to leucocyte capture.

Updated Pathways in Cardiorenal Continuum after Kidney Transplantation

Cardiovascular disease (CVD) remains one of the leading causes for increased morbidity and mortality in chronic kidney disease (CKD). Kidney transplantation is the preferred treatment option for CKD G5. Improved perioperative and postoperative care, personalized immunosuppressive regimes, and refined matching procedures of kidney transplants improves cardiovascular health in the early posttransplant period. However, the long-term burden of CVD is considerable. Previously underrecognized, the role of the complement system alongside innate immunity, inflammaging, structural changes in the glomerular filtration barrier and early vascular ageing also seem to play an important role in the posttransplant management. This review provides up-to-date knowledge on these pathways that may influence the cardiovascular and renal continuum and identifies potential targets for future therapies. Arterial destiffening strategies and the applicability of sodium-glucose cotransporter 2 inhibitors and their role in cardiovascular health after kidney transplantation are also addressed.

Preclinical atherosclerosis and cardiovascular events: Do we have a consensus about the role of preclinical atherosclerosis in the prediction of cardiovascular events?

Atherosclerosis has a long preclinical phase, and the risk of cardiovascular (CV) events may be high in asymptomatic subjects. Conventional risk factors provide information for the statistical probability of developing CV events, but they lack precision in asymptomatic subjects. This review aims to summarize the role of some widely publicized indicators of early atherosclerosis in predicting CV events. The earliest measurable indicator of the atherosclerotic process is endothelial dysfunction, measured by flow-mediated dilation (FMD) of the brachial artery. However, reduced FMD is a stronger predictor of future CV events in patients with existing CV disease than in apparently healthy persons. Alternatively, measurement of carotid artery intima-media thickness does not improve the predictive value of risk factor scores, while detection of asymptomatic atherosclerotic plaques in carotid or common femoral arteries by ultrasound indicates high CV risk. Coronary calcium is a robust and validated help in the estimation of vascular changes and risk, which may improve risk stratification beyond traditional risk factors with relatively low radiation exposure. Arterial stiffness of the aorta, measured as the carotid-femoral pulse wave velocity is an independent marker of CV risk at the population level, but it is not recommended as a routine procedure because of measurement difficulties. Low ankle-brachial index (ABI) indicates flow-limiting atherosclerosis in the lower limbs and indicates high CV risk, while normal ABI does not rule out advanced asymptomatic atherosclerosis. Novel circulating biomarkers are associated with the atherosclerotic process. However, because of limited specificity, their ability to improve risk classification at present remains low.

The role of the cell surface glycocalyx in drug delivery to and through the endothelium

Cell membranes are key interfaces where materials engineering meets biology. Traditionally regarded as just the location of receptors regulating the uptake of molecules, we now know that all mammalian cell membranes are 'sugar coated'. These sugars, or glycans, form a matrix bound at the cell membrane via proteins and lipids, referred to as the glycocalyx, which modulate access to cell membrane receptors crucial for interactions with drug delivery systems (DDS). Focusing on the key blood-tissue barrier faced by most DDS to enable transport from the place of administration to target sites via the circulation, we critically assess the design of carriers for interactions at the endothelial cell surface. We also discuss the current challenges for this area and provide opportunities for future research efforts to more fully engineer DDS for controlled, efficient, and targeted interactions with the endothelium for therapeutic application.

The Importance of Nutraceuticals in COVID-19: What's the Role of Resveratrol?

Since COVID-19 has affected global public health, there has been an urgency to find a solution to limit both the number of infections, and the aggressiveness of the disease once infected. The main characteristic of this infection is represented by a strong alteration of the immune system which, day by day, increases the risk of mortality, and can lead to a multiorgan dysfunction. Because nutritional profile can influence patient’s immunity, we focus our interest on resveratrol, a polyphenolic compound known for its immunomodulating and anti-inflammatory properties. We reviewed all the information concerning the different roles of resveratrol in COVID-19 pathophysiology using PubMed and Scopus as the main databases. Interestingly, we find out that resveratrol may exert its role through different mechanisms. In fact, it has antiviral activity inhibiting virus entrance in cells and viral replication. Resveratrol also improves autophagy and decreases pro-inflammatory agents expression acting as an anti-inflammatory agent. It regulates immune cell response and pro-inflammatory cytokines and prevents the onset of thrombotic events that usually occur in COVID-19 patients. Since resveratrol acts through different mechanisms, the effect could be enhanced, making a totally natural agent particularly effective as an adjuvant in anti COVID-19 therapy.

Acute coronary syndromes in diabetes: Biomarkers of endothelial injury improve risk stratification and help identify predictors of risk

BACKGROUND AND AIMS

Patients with diabetes mellitus (DM) are at an increased risk of acute coronary syndrome (ACS); however, the factors predicting those at highest risk are not well understood. We identified risk factors in those with DM that best predict high ACS risk based on a multiple endothelial injury biomarker algorithm.

METHODS

We studied adults with DM from a clinical registry with measures of a coronary artery disease prediction algorithm (CADPA) score identifying 5-year ACS risk from nine markers. Stepwise logistic regression provided odds ratios for the relationship of age, gender, and individual risk factors not part of the CADPA algorithm with the likelihood of a high risk CADPA score.

RESULTS

We studied 1,613 adults with DM (women: 47.3%, ages 22 to 100, mean age 63.2 years). Of these, 6.1% had a low, 13.2% intermediate, and 80.7% high risk CADPA score. From stepwise logistic regression, women were less likely to have a high risk CADPA score (odds ratio [OR] 0.21, 95% confidence intervals [CI] 0.15-0.29, p<.0001), while age (per standard deviation [SD]) (OR 5.04, [4.12-6.17], p<.0001), body mass index (BMI per SD) (OR 1.34, [1.14-1.58], p = 0.004), hypertension (OR 1.60, [1.15-2.24], p = 0.006), current smoking (OR 2.55, [1.56-4.16], p = 0.0002), hsCRP (per SD) (OR 1.24, [1.01-1.53], p = 0.04), and triglycerides (per SD) (OR 1.26, [1.04-1.54], p = 0.02) were more likely to have a high risk CADPA score.

CONCLUSIONS

Age, men, hypertension, BMI, current smoking, hsCRP, and triglycerides are key factors in those with DM associated with higher ACS risk.

Apremilast Improves Endothelial Glycocalyx Integrity, Vascular and Left Ventricular Myocardial Function in Psoriasis

The phosphodiesterase 4 inhibitor apremilast is used for the treatment of psoriasis. We investigated the effects of apremilast on endothelial glycocalyx, vascular and left ventricular (LV) myocardial function in psoriasis. One hundred and fifty psoriatic patients were randomized to apremilast (n = 50), anti-tumor necrosis factor-α (etanercept; n = 50), or cyclosporine (n = 50). At baseline and 4 months post-treatment, we measured: (1) Perfused boundary region (PBR), a marker of glycocalyx integrity, in sublingual microvessels with diameter 5–25 μm using a Sidestream Dark Field camera (GlycoCheck). Increased PBR indicates damaged glycocalyx. Functional microvascular density, an index of microvascular perfusion, was also measured. (2) Pulse wave velocity (PWV-Complior) and (3) LV global longitudinal strain (GLS) using speckle-tracking echocardiography. Compared with baseline, PBR5–25 μm decreased only after apremilast (−12% at 4 months, p < 0.05) whereas no significant changes in PBR5–25 μm were observed after etanercept or cyclosporine treatment. Compared with etanercept and cyclosporine, apremilast resulted in a greater increase of functional microvascular density (+14% versus +1% versus −1%) and in a higher reduction of PWV. Apremilast showed a greater increase of GLS (+13.5% versus +7% versus +2%) than etanercept and cyclosporine (p < 0.05). In conclusion, apremilast restores glycocalyx integrity and confers a greater improvement of vascular and myocardial function compared with etanercept or cyclosporine after 4 months.