Advanced age results in a diminished endothelial glycocalyx

Age-related microvascular dysfunction is well characterized in rodents and humans, but little is known about the properties of the microvascular endothelial glycocalyx in advanced age. We examined the glycocalyx in microvessels of young and old male C57BL6 mice (young: 6.1 ± 0.1 mo vs. old: 24.6 ± 0.2 mo) using intravital microscopy and transmission electron microscopy and in human participants (young: 29 ± 1 yr vs. old: 60 ± 2 yr) using intravital microscopy. Glycocalyx thickness in mesenteric and skeletal muscle microvessels was 51–54% lower in old compared with young mice. We also observed 33% lower glycocalyx thickness in the sublingual microcirculation of humans in advanced age. The perfused boundary region, a marker of glycocalyx barrier function, was also obtained using an automated capture and analysis system. In advanced age, we observed a 10–22% greater perfused boundary region in mice and humans, indicating a more penetrable glycocalyx. Finally, using this automated analysis system, we examined perfused microvascular density and red blood cell (RBC) fraction. Perfused microvascular density is a marker of microvascular function that reflects the length of perfused microvessel segments in a given area; RBC fraction represents the heterogeneity in RBC presence between microvessel segments. Compared with young, the perfused microvascular density was 16–21% lower and RBC fraction was 5–14% lower in older mice and in older humans. These data provide novel evidence that, across mammalian species, a diminished glycocalyx is present in advanced age and is accompanied by markers of impaired microvascular perfusion. Age-related glycocalyx deterioration may be an important contributor to microvascular dysfunction in older adults and subsequent pathophysiology. NEW & NOTEWORTHY Advanced age is characterized by microvascular dysfunction that contributes to age-related cardiovascular diseases, but little is known about endothelial glycocalyx properties in advanced age. This study reveals, for the first time, lower glycocalyx thickness and barrier function that is accompanied by impaired microvascular perfusion in both mice and humans in advanced age.

Download Full-text

Microcirculatory and glycocalyx properties are lowered by high salt diet but augmented by western diet in genetically heterogeneous mice

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.00656.2021 ◽

2022 ◽

Author(s):

Xiangyu Zheng ◽

Christina Deacon ◽

Abigail J King ◽

Daniel R Machin

Keyword(s):

Barrier Function ◽

Boundary Region ◽

Microvascular Density ◽

Western Diet ◽

High Salt ◽

Chow Diet ◽

Male And Female ◽

Female Mice ◽

Normal Chow ◽

Analysis System

Many individuals in industrialized societies consume a high salt, western diet, however, the effects of this diet on microcirculatory properties and glycocalyx barrier function are unknown. Young genetically heterogeneous male and female mice underwent 12 weeks of normal chow diet (NC), NC diet with 4% salt (NC4%), western diet (WD), or WD with 4% salt (WD4%). Microcirculatory properties and glycocalyx barrier function were evaluated in the mesenteric microcirculation using an intravital microscope equipped with an automated capture and analysis system. Total microvascular density summed across 4-25 μm microvessel segment diameters was lower in NC4% compared to NC and WD (P<0.05). Perfused boundary region (PBR), a marker of glycocalyx barrier function, averaged across 4-25 μm microvessel segment diameters was similar between NC and NC4%, as well as between WD and WD4% (P>0.05). PBR was lower in WD and WD4% compared to NC and NC4% (P<0.05), indicating augmented glycocalyx barrier function in WD and WD4%. There were strong, inverse relationships between PBR and adiposity and blood glucose (r=-0.44 to -0.61, P<0.05). In summary, NC4% induces deleterious effects on microvascular density, whereas WD augments glycocalyx barrier function. Interestingly, the combination of high salt, western diet in WD4% resulted in lower total microvascular density like NC4% and augmented glycocalyx barrier function like WD. These data suggest distinct microcirculatory adaptations to high salt and western diets that coincide when these diets are combined in young genetically heterogeneous male and female mice.

Download Full-text

Automated Measurement of Microvascular Function Reveals Dysfunction in Systemic Sclerosis: A Cross-sectional Study

The Journal of Rheumatology ◽

10.3899/jrheum.170120 ◽

2017 ◽

Vol 44 (11) ◽

pp. 1603-1611 ◽

Cited By ~ 11

Author(s):

Daniel R. Machin ◽

Phillip E. Gates ◽

Hans Vink ◽

Tracy M. Frech ◽

Anthony J. Donato

Keyword(s):

Systemic Sclerosis ◽

Barrier Properties ◽

Boundary Region ◽

Cross Sectional Study ◽

Microvascular Density ◽

Endothelial Glycocalyx ◽

Inverse Association ◽

Healthy Controls ◽

Cross Sectional ◽

Sublingual Microcirculation

Objective.The aim of our study was to determine whether an automated capture and analysis system could detect differences in structure and function of sublingual microvessels in patients with systemic sclerosis (SSc) compared to healthy controls.Methods.Intravital microscopy of the sublingual microcirculation was automatically captured and analyzed in 40 patients with SSc and 10 age-matched healthy controls.Results.Total and perfused microvascular density were lower in patients with SSc compared with controls (total microvascular density: 2471 ± 134 µm/mm2 vs 3067 ± 197 µm/mm2, p = 0.020; perfused microvascular density: 1708 ± 92 µm/mm2 vs 2192 ± 144 µm/mm2, p = 0.009). However, the relative percentage of perfused to total microvascular density was similar between SSc and controls (72 ± 2% vs 71 ± 2%, respectively, p = 0.429). Mean red blood cell (RBC) fraction, which indicates the longitudinal tube hematocrit of microvessel segments, was lower in patients with SSc compared with controls (69 ± 1% vs 77 ± 1%, respectively, p < 0.001). Perfused boundary region (PBR), a marker of endothelial glycocalyx barrier properties, was higher in patients with SSc compared with controls (2.1 ± 0.0 µm vs 1.9 ± 0.0 µm, respectively, p = 0.012), suggestive of a dysfunctional glycocalyx. There was an inverse association of PBR with perfused microvascular density (r = −0.40, p = 0.004) and RBC fraction (r = −0.80, p < 0.001).Conclusion.Our results indicate that automated capture and analysis of sublingual microvessel segments produces detailed, objective microvascular structural and functional data that have allowed us to distinguish patients with SSc from controls. These data suggest that microvascular structural and functional abnormalities present in patients with SSc could be at least partly due to a dysfunctional glycocalyx.

Download Full-text

Association of endothelial glycocalyx integrity and microvascular perfusion with novel echocardiographic markers and carotid intima-media thickness in patients with psoriasis

European Heart Journal - Cardiovascular Imaging ◽

10.1093/ehjci/jeaa356.136 ◽

2021 ◽

Vol 22 (Supplement_1) ◽

Author(s):

P Rafouli-Stergiou ◽

I Ikonomidis ◽

G Makavos ◽

J Thymis ◽

G Pavlidis ◽

...

Keyword(s):

Myocardial Dysfunction ◽

Intima Media Thickness ◽

Carotid Intima Media Thickness ◽

Microvascular Density ◽

Microvascular Perfusion ◽

Myocardial Deformation ◽

Endothelial Glycocalyx ◽

Media Thickness ◽

Flow Reserve ◽

Glycocalyx Thickness

Abstract Funding Acknowledgements Type of funding sources: None. Introduction Psoriasis has been associated with vascular and myocardial dysfunction through mechanisms of inflammation and oxidative stress. Purpose We aimed to evaluate sublingual microvascular perfusion and glycocalyx barrier properties in psoriasis patients, as well as their correlation with coronary microcirculatory function, markers of myocardial deformation and atherosclerosis (carotid intima-media thickness, IMT). Methods We examined 241 patients with psoriasis and 160 controls, adjusted for age, sex, BMI, smoking, LV mass, heart rate, hyperlipidemia, and office SBP. Perfusion boundary region (PBR), a marker of glycocalyx barrier function, was measured non-invasively in sublingual microvessels with a diameter ranging from 5-25 µm using a dedicated camera (Side field dark imaging, Micrsoscan, Nedelrands). Increased PBR indicates reduced glycocalyx thickness. Indexes of microvascular perfusion, including red blood cell (RBC) filling percentage and functional microvascular density, were also calculated. We measured coronary flow reserve (CFR), carotid IMT and markers of myocardial deformation by speckle tracking imaging utilizing echocardiography [peak twisting, the percentage changes between peak twisting, and untwisting at mitral valve opening (%dpTw – UtwMVO), at peak (%dpTw – UtwPEF), and the end of early LV diastolic filling (%dpTw – UtwEDF)]. Results Psoriasis patients had higher PBR (PBR5-25: 2.131 ± 0.296 vs. 1.769 ± 0.306; PBR5-9: 1.183 ± 0.150 vs. 1.051 ± 0.132; PBR10-19: 2.318 ± 0.581 vs. 1.993 ± 0.365; PBR20-25: 2.650 ± 0.461 vs. 2.269 ± 0.492, all p < 0.05) and impaired LV twisting-untwisting markers compared to controls (pTw: 14.8 ± 7.8 vs. 13.9 ± 3.5; UtwMVO: 10.3 ± 7.3 vs. 9 ± 4.3; %dpTw – UtwMVO: 31 ± 4.1 vs. 38 ± 7; pTwVel: 105 ± 83 vs. 89 ± 21; pUtwVel: -100 ± 53 vs. -93 ± 31, all p < 0.05). In psoriatic population, levels of PBR5-25 and PBR10-19 were inversely correlated to CFR (r=-0.15 and r=-0.17). The first one was also reversely related to peak LV untwisting at aortic valve closure (r=-0.14). Increased levels of PBR5-9 were associated with reduced untwisting at end of the mitral inflow E wave (UtwEDF, r=-0.13) and reduced percentage difference between peak twisting and untwisting at MVO (%dpTw-UntwMVO) (r=-0.15). Furthermore, decreased RBC filling percentage and perfused microvascular density were related to worse LV longitudinal strain (4-chamber) (r=-0.15), and increased IMT (r=-0.14). Finally, a positive correlation between perfused microvascular density and %dpTw-UntwMVO was observed in patients with psoriasis (r = 0.14). All correlations were statistically significant (p < 0.05). Conclusion Endothelial glycocalyx thickness is reduced in patients with psoriasis and is associated with impaired coronary and myocardial function, and vascular atherosclerosis.

Download Full-text

Microvascular dysfunction in COVID-19: the MYSTIC study

Angiogenesis ◽

10.1007/s10456-020-09753-7 ◽

2020 ◽

Author(s):

Alexandros Rovas ◽

Irina Osiaevi ◽

Konrad Buscher ◽

Jan Sackarnd ◽

Phil-Robin Tepasse ◽

...

Keyword(s):

Microvascular Dysfunction ◽

Boundary Region ◽

Dark Field ◽

Endothelial Glycocalyx ◽

Vascular Involvement ◽

Enzyme Linked Immunosorbent Assay ◽

Blood Levels ◽

Vascular Density ◽

Sidestream Dark Field ◽

Cross Sectional

Abstract Rationale Pre-clinical and autopsy studies have fueled the hypothesis that a dysregulated vascular endothelium might play a central role in the pathogenesis of ARDS and multi-organ failure in COVID-19. Objectives To comprehensively characterize and quantify microvascular alterations in patients with COVID-19. Methods Hospitalized adult patients with moderate-to-severe or critical COVID-19 (n = 23) were enrolled non-consecutively in this prospective, observational, cross-sectional, multi-center study. Fifteen healthy volunteers served as controls. All participants underwent intravital microscopy by sidestream dark field imaging to quantify vascular density, red blood cell velocity (VRBC), and glycocalyx dimensions (perfused boundary region, PBR) in sublingual microvessels. Circulating levels of endothelial and glycocalyx-associated markers were measured by multiplex proximity extension assay and enzyme-linked immunosorbent assay. Measurements and main results COVID-19 patients showed an up to 90% reduction in vascular density, almost exclusively limited to small capillaries (diameter 4–6 µm), and also significant reductions of VRBC. Especially, patients on mechanical ventilation showed severe glycocalyx damage as indicated by higher PBR values (i.e., thinner glycocalyx) and increased blood levels of shed glycocalyx constituents. Several markers of endothelial dysfunction were increased and correlated with disease severity in COVID-19. PBR (AUC 0.75, p = 0.01), ADAMTS13 (von Willebrand factor-cleaving protease; AUC 0.74, p = 0.02), and vascular endothelial growth factor A (VEGF-A; AUC 0.73, p = 0.04) showed the best discriminatory ability to predict 60-day in-hospital mortality. Conclusions Our data clearly show severe alterations of the microcirculation and the endothelial glycocalyx in patients with COVID-19. Future therapeutic approaches should consider the importance of systemic vascular involvement in COVID-19.

Download Full-text

Outer retinal tubulation formation and clinical course of advanced age-related macular degeneration

Scientific Reports ◽

10.1038/s41598-021-94310-5 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Alessandro Arrigo ◽

Emanuela Aragona ◽

Ottavia Battaglia ◽

Andrea Saladino ◽

Alessia Amato ◽

...

Keyword(s):

Macular Degeneration ◽

Müller Cells ◽

Geographic Atrophy ◽

Age Related Macular Degeneration ◽

Advanced Age ◽

Age Related ◽

Dry Amd ◽

Foveal Sparing ◽

Wet Amd

AbstractOuter retinal tubulations (ORT) are a relatively new finding characterizing outer retinal atrophy. The main aim of the present study was to describe ORT development in advanced age-related macular degeneration (AMD) and to assess its relationship with disease’s severity. Patients with advanced AMD characterized either by macular neovascularization or geographic atrophy, showing signs of outer retinal disruption or retinal pigment epithelium atrophy on structural optical coherence tomography (OCT) at the inclusion examination were prospectively recruited. All the patients underwent complete ophthalmologic evaluation, structural OCT scans and fundus autofluorescence imaging. The planned follow-up was of 3-years. Main outcome measures were ORT prevalence, mechanism of ORT formation, mean time needed for complete ORT formation, best-corrected visual acuity (BCVA), definitely decreased autofluorescence (DDAF) area, questionably decreased autofluorescence (QDAF) area, retinal layer thickness, foveal sparing, number of intravitreal injections. We also assessed the possible role of external limiting membrane (ELM) and Müller cells in ORT pathogenesis. Seventy eyes (70 patients) were included; 43 showed dry AMD evolving to geographic atrophy, while 27 displayed the features of wet AMD. Baseline BCVA was 0.5 ± 0.5 LogMAR, decreasing to 0.9 ± 0.5 LogMAR at the 3-year follow-up (p < 0.01). We detected completely formed ORT in 26/70 eyes (37%), subdivided as follows: 20 eyes (77%) wet AMD and 6 eyes (23%) dry AMD (p < 0.01). ORT took 18 ± 8 months (range 3–35 months) to develop fully. We described the steps leading to ORT development, characterized by progressive involvement of, and damage to the photoreceptors, the ELM and the RPE. Eyes displaying ORT were associated with a smaller QDAF area, less retinal layers damage and lower rate of foveal sparing than eyes free of ORT (p < 0.01). We also described pigment accumulations simulating ORT, which were detected in 16/70 eyes (23%), associated with a greater loss of foveal sparing, increased DDAF area and smaller QDAF area at the 3-year follow-up (p < 0.01). In conclusion, this study provided a description of the steps leading to ORT development in AMD. ELM and Müller cells showed a role in ORT pathogenesis. Furthermore, we described a subtype of pigment hypertrophy mimicking ORT, evaluating its clinical utility.

Download Full-text

Bone Morphogenetic Proteins and Diabetic Retinopathy

Biomolecules ◽

10.3390/biom11040593 ◽

2021 ◽

Vol 11 (4) ◽

pp. 593

Author(s):

Khaled Elmasry ◽

Samar Habib ◽

Mohamed Moustafa ◽

Mohamed Al-Shabrawey

Keyword(s):

Diabetic Retinopathy ◽

Bone Morphogenetic Proteins ◽

Potential Role ◽

Microvascular Dysfunction ◽

Cardiovascular Complications ◽

Bmp Signaling ◽

Age Related Macular Degeneration ◽

Age Related ◽

Retinal Inflammation ◽

Underlying Mechanisms

Bone morphogenetic proteins (BMPs) play an important role in bone formation and repair. Recent studies underscored their essential role in the normal development of several organs and vascular homeostasis in health and diseases. Elevated levels of BMPs have been linked to the development of cardiovascular complications of diabetes mellitus. However, their particular role in the pathogenesis of microvascular dysfunction associated with diabetic retinopathy (DR) is still under-investigated. Accumulated evidence from our and others’ studies suggests the involvement of BMP signaling in retinal inflammation, hyperpermeability and pathological neovascularization in DR and age-related macular degeneration (AMD). Therefore, targeting BMP signaling in diabetes is proposed as a potential therapeutic strategy to halt the development of microvascular dysfunction in retinal diseases, particularly in DR. The goal of this review article is to discuss the biological functions of BMPs, their underlying mechanisms and their potential role in the pathogenesis of DR in particular.

Download Full-text

Methylation Marks of Blood Leukocytes of Native Hucul Mares Differentiated in Age

International Journal of Genomics ◽

10.1155/2019/2839614 ◽

2019 ◽

Vol 2019 ◽

pp. 1-9

Author(s):

T. Ząbek ◽

E. Semik-Gurgul ◽

T. Szmatoła ◽

A. Gurgul ◽

A. Fornal ◽

...

Keyword(s):

Cancer Progression ◽

Late Onset ◽

Advanced Age ◽

Farm Animals ◽

Blood Leukocytes ◽

Data Set ◽

Reduced Representation ◽

Cellular Signal

Horses are one of the longest-living species of farm animals. Advanced age is often associated with a decrease in body condition, dysfunction of immune system, and late-onset disorders. Due to this, the search for new solutions in the prevention and treatment of pathological conditions of the advanced age of horses is desirable. That is why the identification of aging-related changes in the horse genome is interesting in this respect. In the recent years, the research on aging includes studies of age-related epigenetic effects observed on the DNA methylation level. We applied reduced representation bisulfite sequencing (RRBS) to uncover a range of age DMR sites in genomes of blood leukocytes derived from juvenile and aged horses of native Hucul breed. Genes colocated with age-related differentially methylated regions (age DMRs) are the members of pathways involved in cellular signal transduction, immune response, neurogenesis, differentiation, development, and cancer progression. A positive correlation was found between methylation states and gene expression in particular loci from our data set. Some of described age DMR-linked genes were also reported elsewhere. Obtained results contribute to the knowledge about the molecular basis of aging of equine blood cells.

Download Full-text

Age-related changes in barrier function in mouse brain

Archives of Gerontology and Geriatrics ◽

10.1016/s0167-4943(97)00022-8 ◽

1997 ◽

Vol 25 (3) ◽

pp. 321-331 ◽

Cited By ~ 6

Author(s):

Masaki Ueno ◽

Ichiro Akiguchi ◽

Masanori Hosokawa ◽

Masahiko Shinnou ◽

Haruhiko Sakamoto ◽

...

Keyword(s):

Mouse Brain ◽

Barrier Function ◽

Age Related ◽

Age Related Changes

Download Full-text

Heightened self-reactivity associated with selective survival, but not expansion, of naïve virus-specific CD8+ T cells in aged mice

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1525167113 ◽

2016 ◽

Vol 113 (5) ◽

pp. 1333-1338 ◽

Cited By ~ 30

Author(s):

Kylie M. Quinn ◽

Sophie G. Zaloumis ◽

Tania Cukalac ◽

Wan-Ting Kan ◽

Xavier Y. X. Sng ◽

...

Keyword(s):

T Cells ◽

T Cell ◽

Influenza A ◽

Cytotoxic T Lymphocyte ◽

Clonal Diversity ◽

Cell Receptor ◽

Advanced Age ◽

Age Related ◽

Self Recognition ◽

Underlying Mechanisms

In advanced age, decreased CD8+ cytotoxic T-lymphocyte (CTL) responses to novel pathogens and cancer is paralleled by a decline in the number and function of naïve CTL precursors (CTLp). Although the age-related fall in CD8+ T-cell numbers is well established, neither the underlying mechanisms nor the extent of variation for different epitope specificities have been defined. Furthermore, naïve CD8+ T cells expressing high levels of CD44 accumulate with age, but it is unknown whether this accumulation reflects their preferential survival or an age-dependent driver of CD8+ T-cell proliferation. Here, we track the number and phenotype of four influenza A virus (IAV)-specific CTLp populations in naïve C57BL/6 (B6) mice during aging, and compare T-cell receptor (TCR) clonal diversity for the CD44hi and CD44lo subsets of one such population. We show differential onset of decline for several IAV-specific CD8+ T-cell populations with advanced age that parallel age-associated changes in the B6 immunodominance hierarchy, suggestive of distinct impacts of aging on different epitope-specific populations. Despite finding no evidence of clonal expansions in an aged, epitope-specific TCR repertoire, nonrandom alterations in TCR usage were observed, along with elevated CD5 and CD8 coreceptor expression. Collectively, these data demonstrate that naïve CD8+ T cells expressing markers of heightened self-recognition are selectively retained, but not clonally expanded, during aging.

Download Full-text