Vasoregression: A Shared Vascular Pathology Underlying Macrovascular And Microvascular Pathologies?

Excess adiponectin in eyes with progressive ocular vascular diseases

Anti-vascular endothelial growth factor (VEGF) therapies are now the first-line treatment for many ocular diseases, but some patients are non-responders to these therapies. The purpose of this study was to determine whether the level of adiponectin increased the pathogenesis of retinal edema and neovascularization in the retina of progressive ocular vascular diseases. We examined the role played by adiponectin in two types of cells and animal models which are retinal vein occlusion (RVO) and oxygen-induced retinopathy (OIR) mice. Our results showed that an injection of anti-adiponectin antibody ameliorated the retinal edema and ischemia through the depression of the expression level of VEGF-related factors and tight junction-related proteins in the retina of RVO mice. The intravitreal injection of anti-adiponectin antibody also decreased the degree of retinal neovascularization in an OIR mice. In addition, exposure of human retinal microvascular endothelial cells and human brain microvascular pericytes in culture to adiponectin increased both the vascular permeability and neovascularization through the increase of inflammatory factor and the dropout of the pericytes. These findings indicate that adiponectin plays a critical role in retinal edema and neovascularization, and adiponectin is a potential therapeutic target for the treatment of diabetic macular edema, proliferative diabetic retinopathy, and RVO.

Intravitreal injection of peptides PnPa11 and PnPa13, derivatives of Phoneutria nigriventer spider venom, prevents retinal damage

Background:

PnPa11 and PnPa13 are synthetic peptides derived from Phoneutria nigriventer spider venom, which display antinociceptive and neuroprotective properties. In this work, we evaluated the safety of intravitreal use and the neuroprotective effect of these peptides.

Methods:

The cytotoxicity and the antiangiogenic activity of these peptides were evaluated by the sulforhodamine-B method and chicken chorioallantoic membrane (CAM) assay, respectively. The in vivo safety was analyzed in Wistar rats that were intravitreally injected with different doses (0.50; 1.25; 2.50; 3.75 and 5.00 µg/mL) of these peptides (right eye, n = 6). The retinal function was assessed by electroretinography exams (ERG), intraocular pressure (IOP), and histological analyzes. In order to investigate the neuroprotective effect, Wistar rats received intravitreal injections (right eye, n = 6) of peptides at 1.25 µg/mL and then were exposed to blue LED light. In addition, the visual function and the retinal microstructure were verified.

Results:

Cytotoxicity analyses demonstrated that the peptides did not present any toxicity over ARPE-19 (adult retinal pigmented epithelial) cell line and the antiangiogenic study highlighted that the peptides promoted the reduction of blood vessels. The intravitreal injection did not cause major changes, neither induced any irreversible damage. In the retinal degeneration assay, the ERG records demonstrated that the prior treatment with PnPa11 and PnPa13 protected the retina from damage. Morphological analyses confirmed the ERG findings. Immunoblotting analyses revealed that PnPa11 increased Erk1/2, NR2A, and NR2B retinal expression after the light stress model, but did not cause Akt1 activation, while PnPa13 prevented Erk1/2 and Akt1 dephosphorylation.

Conclusions:

The intraocular administration of these peptides was well tolerated and presented protective activity against retinal degeneration, suggesting the potential use of these peptides as neuroprotectors in the ophthalmological field.

Oscillatory fluid-induced mechanobiology in heart valves with parallels to the vasculature

Forces generated by blood flow are known to contribute to cardiovascular development and remodeling. These hemodynamic forces induce molecular signals that are communicated from the endothelium to various cell types. The cardiovascular system consists of the heart and the vasculature, and together they deliver nutrients throughout the body. While heart valves and blood vessels experience different environmental forces and differ in morphology as well as cell types, they both can undergo pathological remodeling and become susceptible to calcification. In addition, while the plaque morphology is similar in valvular and vascular diseases, therapeutic targets available for the latter condition are not effective in the management of heart valve calcification. Therefore, research in valvular and vascular pathologies and treatments have largely remained independent. Nonetheless, understanding the similarities and differences in development, calcific/fibrous pathologies and healthy remodeling events between the valvular and vascular systems can help us better identify future treatments for both types of tissues, particularly for heart valve pathologies which have been understudied in comparison to arterial diseases.

Characterization of Retinal Microvascular Complications and the Effects of Endoplasmic Reticulum Stress in Mouse Models of Diabetic Atherosclerosis

Purpose

Recent evidence suggests that there is a correlation between the micro- and macrovascular complications of diabetes mellitus. The aim of this study is to investigate the molecular mechanisms by which diabetes promotes the development of microvascular disease (diabetic retinopathy [DR]) through characterization of the effects of hyperglycemia in the retina of mouse models of diabetic atherosclerosis.

Methods

Hyperglycemia was induced in apolipoprotein E-deficient (ApoE-/-) mice, a model of accelerated atherosclerosis, either through streptozotocin (STZ) injection or introduction of the Ins2Akita mutation (ApoE-/-Ins2+/Akita). Another subset of ApoE-/- mice was supplemented with glucosamine (GlcN). To attenuate atherosclerosis, subsets of mice from each experimental group were treated with the chemical chaperone, 4-phenylbutyric acid (4PBA). Eyes from 15-week-old mice were either trypsin digested and stained with periodic acid-Schiff (PAS) or frozen for cryostat sectioning and immunostained for endoplasmic reticulum (ER) stress markers, including C/EBP homologous protein (CHOP) and 78-kDa glucose-regulated protein (GRP78). PAS-stained retinal flatmounts were analyzed for microvessel density, acellular capillaries, and pericyte ghosts.

Results

Features of DR, including pericyte ghosts and reduced microvessel density, were observed in hyperglycemic and GlcN-supplemented mice. Treatment with 4PBA reduced ER stress in the retinal periphery and attenuated DR in the experimental groups.

Conclusions

Mouse models of diabetic atherosclerosis show characteristic pathologies of DR that correlate with atherosclerosis. The increased magnitude of these changes and responses to 4PBA in the peripheral retina suggest that future studies should be aimed at assessing regional differences in mechanisms of ER stress-related pathways in these mouse models.

Berendschot T, S.A.G. Schouten J, Kroon AA, van der Kallen CJ, Henry RM, van Dongen MC, J.P.M. Eussen S, H.C.M. Savelberg H, van der Berg JD, Schaper NC, Schram MT, Stehouwer CD. Higher levels of daily physical activity are associated with better skin microvascular function in type 2 diabetes-The Maastricht Study

OBJECTIVE

Physical activity may provide a means for the prevention of cardiovascular disease via improving microvascular function. Therefore, this study investigated whether physical activity is associated with skin and retinal microvascular function.

METHODS

In The Maastricht Study, a population-based cohort study enriched with type 2 diabetes (n = 1298, 47.3% women, aged 60.2 ± 8.1 years, 29.5% type 2 diabetes), we studied whether accelerometer-assessed physical activity and sedentary time associate with skin and retinal microvascular function. Associations were studied by linear regression and adjusted for major cardiovascular risk factors. In addition, we investigated whether associations were stronger in type 2 diabetes.

RESULTS

In individuals with type 2 diabetes, total physical activity and higher-intensity physical activity were independently associated with greater heat-induced skin hyperemia (regression coefficients per hour), respectively, 10 (95% CI: 1; 18) and 36 perfusion units (14; 58). In individuals without type 2 diabetes, total physical activity and higher-intensity physical activity were not associated with heat-induced skin hyperemia. No associations with retinal arteriolar %-dilation were identified.

CONCLUSION

Higher levels of total and higher-intensity physical activity were associated with greater skin microvascular vasodilation in individuals with, but not in those without, type 2 diabetes.

Cardiovascular risk factors as determinants of retinal and skin microvascular function: The Maastricht Study

Objective

Microvascular dysfunction is an important underlying mechanism of microvascular diseases. Determinants (age, sex, hypertension, dyslipidemia, hyperglycemia, obesity, and smoking) of macrovascular diseases affect large-artery endothelial function. These risk factors also associate with microvascular diseases. We hypothesized that they are also determinants of microvascular (endothelial) function.

Methods

In The Maastricht Study, a type 2 diabetes-enriched population-based cohort study (n = 1991, 51% men, aged 59.7±8.2 years), we determined microvascular function as flicker light-induced retinal arteriolar %-dilation and heat-induced skin %-hyperemia. Multiple linear regression analyses were used to assess the associations of cardiovascular risk factors (age, sex, waist circumference, total-to-high-density lipoprotein (HDL) cholesterol ratio, fasting plasma glucose (FPG), 24-h systolic blood pressure, and cigarette smoking) with retinal and skin microvascular function.

Results

In multivariate analyses, age and FPG were inversely associated with retinal and skin microvascular function (regression coefficients per standard deviation (SD) were -0.11SD (95%CI: -0.15;-0.06) and -0.12SD (-0.17;-0.07) for retinal arteriolar %-dilation and -0.10SD (-0.16;-0.05) and -0.11SD (-0.17;-0.06) for skin %-hyperemia, respectively. Men and current smokers had -0.43SD (-0.58;-0.27) and -0.32SD (-0.49;-0.15) lower skin %-hyperemia, respectively. 24-h systolic blood pressure, waist circumference, and total-to-HDL cholesterol ratio were not statistically significantly associated with these microvascular functions.

Conclusions

Associations between cardiovascular risk factors and retinal and skin microvascular function show a pattern that is partly similar to the associations between cardiovascular risk factors and macrovascular function. Impairment of microvascular function may constitute a pathway through which an adverse cardiovascular risk factor pattern may increase risk of diseases that are partly or wholly of microvascular origin.