Endothelial Surface Layer Degradation by Chronic Hyaluronidase Infusion Induces Proteinuria in Apolipoprotein E-Deficient Mice

Functional studies show that disruption of endothelial surface layer (ESL) is accompanied by enhanced sensitivity of the vasculature towards atherogenic stimuli. However, relevance of ESL disruption as causal mechanism for vascular dysfunction remains to be demonstrated. We examined if loss of ESL through enzymatic degradation would affect vascular barrier properties in an atherogenic model. Eight week old male apolipoprotein E deficient mice on Western-type diet for 10 weeks received continuous active or heat-inactivated hyaluronidase (10 U/hr, i.v.) through an osmotic minipump during 4 weeks. Blood chemistry and anatomic changes in both macrovasculature and kidneys were examined. Infusion with active hyaluronidase resulted in decreased ESL (0.32±0.22 mL) and plasma volume (1.03±0.18 mL) compared to inactivated hyaluronidase (0.52±0.29 mL and 1.28±0.08 mL, p<0.05 respectively).Active hyaluronidase increased proteinuria compared to inactive hyaluronidase (0.27±0.02 vs. 0.15±0.01 µg/µg protein/creatinin, p<0.05) without changes in glomerular morphology or development of tubulo-interstitial inflammation. Atherosclerotic lesions in the aortic branches showed increased matrix production (collagen, 32±5 vs. 18±3%; glycosaminoglycans, 11±5 vs. 0.1±0.01%, active vs. inactive hyaluronidase, p<0.05). ESL degradation in apoE deficient mice contributes to reduced increased urinary protein excretion without significant changes in renal morphology. Second, the induction of compositional changes in atherogenic plaques by hyaluronidase point towards increased plaque vulnerability. These findings support further efforts to evaluate whether ESL restoration is a valuable target to prevent (micro) vascular disease progressio

Glycocalyx, cardiometabolic disease and inflammation

De glycocalyx is een laag moleculen tussen het endotheel (de binnenbekleding van de bloedvaten) en het bloed. De glycocalyx zorgt ervoor dat er geen lekkage ontstaat en voorkomt dat bloedplaatjes en afweercellen vastplakken aan de vaatwand. Dit maakt de glycocalyx een interessant aangrijpingspunt voor nieuwe medicijnen tegen aderverkalking (atherosclerose). Vroege schade aan het endotheel kan atherosclerose versterken. Lysette Broekhuizen onderzocht technieken om de glycocalyx in vivo te bekijken en manieren om schade aan de glycocalyx te herstellen

Endothelial glycocalyx as potential diagnostic and therapeutic target in cardiovascular disease

Purpose of review The endothelial glycocalyx has emerged as a potential orchestrator of vascular homeostasis. Under physiological conditions, the glycocalyx is an important contributor to the regulation of vascular permeability for macromolecules as well for the adhesion of circulating cells. In line, the potential role of the glycocalyx in maintaining the antiatherogenic properties of the vessel wall may have important clinical implications. In the present review, we provide an overview of recent developments and a glance at the future of establishing endothelial glycocalyx as a crucial player in cardiovascular protection. Recent findings Novel methods to estimate glycocalyx dimensions in vivo (using Orthogonal Polarization Spectral imaging or Sideview Darkfield imaging) as well as progressive insight into the enzymes involved in glycocalyx synthesis will be crucial in the assessment of this structure as a potential surrogate marker or therapeutic target for cardiovascular risk. The validation of these 'imaging' techniques and the integration with glycocalyx degradation products in plasma will allow us to test the value of the endothelial glycocalyx in estimating cardiovascular risk. Summary The endothelial glycocalyx, protecting the vascular wall against atherogenic influents, could be used for cardiovascular risk stratification. For this purpose, new methods to estimate glycocalyx dimension are promisin

The association between the gene encoding 5-lipoxygenase activating protein and abdominal aortic aneurysms

Background: Genetic variation in the gene ALOX5AP, encoding arachidonate 5-lipoxygenase-activating protein, have been suggested to increase risk for myocardial infarction and stroke. Leukotrienes (LTs) that derive from the 5-lipoxygenase (5-LO) cascade have been implicated in the pathogenesis of abdominal aortic aneurysm (AAA).\ud \ud Methods and results: The association of the ALOX5AP haplotypes with AAA was assessed in a large population-based cohort of 613 men aged ≥65 years with screen-detected AAAs and 707 randomly selected age-matched controls without AAA. Taqman assays were used to assess seven previously described single nucleotide polymorphisms (SNPs) of ALOX5AP. Haplotypes A and B were defined by the four SNPs (SG13S25, SG13S114, SG13S89, SG13S32) and (SG13S377, SG13S114, SG13S41, SG13S35), respectively. After adjustment for cardiovascular risk factors, there were no significant differences in the distribution of ALOX5AP haplotypes between cases and controls.\ud \ud Conclusion: A genetic predisposition to up-regulation of LT mediators is unlikely to play a dominant role in the pathogenesis of AAA

Measuring endothelial glycocalyx dimensions in humans: a potential novel tool to monitor vascular vulnerability

The endothelial glycocalyx is increasingly considered as an intravascular compartment that protects the vessel wall against pathogenic insults. The purpose of this study was to translate an established experimental method of estimating capillary glycocalyx dimension into a clinically useful tool and to assess its reproducibility in humans. We first evaluated by intravital microscopy the relation between the distance between the endothelium and erythrocytes, as a measure of glycocalyx thickness, and the transient widening of the erythrocyte column on glycocalyx compression by passing leukocytes in hamster cremaster muscle capillaries. We subsequently assessed sublingual microvascular glycocalyx thickness in 24 healthy men using orthogonal polarization spectral imaging. In parallel, systemic glycocalyx volume (using a previously published tracer dilution technique) as well as cardiovascular risk profiles were assessed. Estimates of microvascular glycocalyx dimension from the transient erythrocyte widening correlated well with the size of the erythrocyte-endothelium gap (r = 0.63). Measurements in humans were reproducible (0.58 +/- 0.16 and 0.53 +/- 0.15 microm, coefficient of variance 15 +/- 5%). In univariate analysis, microvascular glycocalyx thickness significantly correlated with systemic glycocalyx volume (r = 0.45), fasting plasma glucose (r = 0.43), and high-density lipoprotein-cholesterol (r = 0.40) and correlated negatively with low-density lipoprotein-cholesterol (r = -0.41) as well as body mass index (r = -0.45) (all P < 0.05). In conclusion, the dimension of the endothelial glycocalyx can be measured reproducibly in humans and is related to cardiovascular risk factors. It remains to be tested whether glycocalyx dimension can be used as an early marker of vascular damage and whether therapies aimed at glycocalyx repair can protect the vasculature against pathogenic challenge

Physical activity, metabolic syndrome, and coronary risk: the EPIC-Norfolk prospective population study

Objective: We investigated the association between physical activity, metabolic syndrome (MS), and the risk of future coronary heart disease (CHD) and mortality due to CHD in middle-aged men and women. Design: Prospective cohort study. Subjects: A total of 10,134 men and women aged 45-79 years at baseline, were selected from the European Prospective Investigation into Cancer and Nutrition (EPIC)-Norfolk cohort. Cardiovascular risk factors and physical activity levels were recorded at baseline. Rates of CHD and CHD mortality were recorded during a follow-up of 10.9 years. Results: The prevalence of MS was 37.6% in men and 30.2% in women. Hazard ratios (HRs) for future CHD were 1.95 (95% CI 1.65-2.31) for men with MS and 3.17 (95% CI 2.53-3, 97) for women with MS, compared to those without MS. HRs adjusted for age and smoking were 1.52 (95% CI 1.29-1.81) for men and 1.76 (95% CI 1.39-2.23) for women. Additional adjustment for physical activity did not attenuate these risk estimates further [ HRs 1.51 (95% CI 1.27-1.79) and 1.74 (95% CI 1.38-2.21), respectively]. CHD risk associated with MS was substantially lower among participants who were physically active. There was no longer a significant difference in CHD event rate between men with MS who were active and men without MS who were inactive (11.5% vs. 12.8%). For women, similar associations were observed (5.3% vs. 5.6%). We found evidence for significant effect modification (p for interaction = 0.006) such that physical activity affected the association between MS and CHD risk. Conclusion: Middle-aged men and women with MS have an increased risk for future CHD. This CHD risk associated with MS is substantially lower among those who are physically active. Participants with MS who were physically active had a lower CHD risk than people without MS who were physically inactiv

Reduction of monocyte chemoattractant protein 1 and macrophage migration inhibitory factor by a polyphenol-rich extract in subjects with clustered cardiometabolic risk factors

Inflammation is a hallmark of the metabolic syndrome, which also contributes to a pro-atherogenic state. NF-κB activation, a critical step in regulating inflammatory reactions, can be inhibited by polyphenol (PF) extracts, at least in vitro. In the present study, we set out to study whether a PF-rich extract could attenuate the chronic inflammatory state and/or an acute immune response in vivo in subjects with clustered metabolic risk factors. A commercially available, PF-rich extract (500 mg daily) or placebo was administered for 4 weeks to thirty-four subjects with two or more metabolic risk factors using a randomised, double-blind, cross-over design. During the final study visit, an acute inflammatory challenge (lipopolysaccharide (LPS) 1 ng/kg body weight) was administered to a random subgroup of subjects (PF-rich extract (n 12) and placebo (n 12)). The PF-rich extract modestly reduced the inflammatory chemokines monocyte chemoattractant protein 1 (MCP-1) and macrophage migration inhibitory factor (MIF) (MCP-1 - 6.5 % (PF, median 116 (interquartile range 97-136) pg/ml v. placebo, median 124 (interquartile range 105-153) pg/ml; P < 0.05); MIF - 10.8 % (PF, median 2512 (interquartile range 1898-3972) pg/ml v. placebo, median 2814.5 (interquartile range 2296-3852) pg/ml; P < 0.05); however, other measured markers of inflammation and cardiometabolic disease, such as C-reactive protein, IL-6, HDL-cholesterol, adiponectin and oxidised LDL, remained unaffected. Following the LPS challenge, we found a statistically significant 48 % reduction of MCP-1 production in the PF-rich extract group (n 12) v. placebo (n 12) over 6 h (PF 766 (sd 155) v. placebo 1466 (sd 989) ng/ml; P < 0.05, area under the curve). In conclusion, short-term oral administration of the PF-rich extract caused a modest anti-inflammatory effect in subjects with clustered metabolic risk factors. Further dose-ranging studies are needed to evaluate whether and to what extent PF-rich extracts can be used to reduce the pro-inflammatory state in subjects with metabolic diseases at increased cardiovascular ris