A cardiologist view of vascular disease in diabetes

Complement Factor C1q Mediates Vascular Endothelial Dysfunction in STZ-Induced Diabetic Mice

Diabetes is a significant global public health issue with implications for vascular endothelial cells (ECs) dysfunction and the subsequent development and advancement of diabetes complications. This study aims to compare the cellular and molecular properties of the aorta in normal and streptozotocin (STZ)-induced diabetic mice, with a focus on elucidating potential mechanism underlying EC dysfunction. Here, we performed a single-cell RNA sequencing survey of 32,573 cells from the aorta of normal and STZ-induced diabetic mice. We found a compendium of 10 distinct cell types, mainly ECs, smooth muscle cells, fibroblast, pericyte, immune cells, and stromal cells. As the diabetes condition progressed, we observed a subpopulation of aortic ECs that exhibited significantly elevated expression of complement (C) molecule C1qa compared with their healthy counterparts. This increased expression of C1qa was found to induce reactive oxygen species (ROS) production, facilitate EC migration and increased permeability, and impair the vasodilation within the aortic segment of mice. Furthermore, AAV-Tie2-shRNA-C1qa was administered into diabetic mice by tail vein injection, showing that inhibition of C1qa in the endothelium led to a reduction in ROS production, decreased vascular permeability, and improved vasodilation. Collectively, these findings highlight the crucial involvement of C1qa in endothelial dysfunction associated with diabetes.

ARTICLE HIGHLIGHTS

Serotonin and Interleukin 10 Can Influence the Blood and Urine Viscosity in Gestational Diabetes Mellitus and Pregnancy-Specific Urinary Incontinence

Serotonin and interleukin 10 (IL-10) may play a role in gestational diabetes mellitus. Hyperglycemic environment, the detrusor musculature of the bladder and pelvic floor muscles may become damaged, leading to urination problems and urine viscosity in pregnant women with gestational diabetes mellitus and pregnancy-specific urinary incontinence. Urine and blood samples were collected from pregnant women between 24 and 28 weeks of gestation. The serotonin concentration and cytokine IL-10 levels were evaluated in plasma and urine. In the total blood and urine, the viscosity was evaluated in the presence and absence of exogenous serotonin and IL-10. The plasma serotonin levels decreased, while the urine serotonin levels increased in the normoglycemic incontinent (NG-I), hyperglycemic continent (GDM-C), and hyperglycemic incontinent (GDM-I) groups. The IL-10 in the plasma decreased in the GDM-I group and was higher in the urine in the NG-I and GDM-I groups. The blood viscosity was higher, independently of urinary incontinence, in the GDM groups. The serotonin increased the blood viscosity from women with GDM-C and urine in the NG-I, GDM-C, and GDM-I groups. Blood and urine in the presence of IL-10 showed a similar viscosity in all groups studied. Also, no difference was observed in the viscosity in either the blood or urine when in the presence of serotonin and IL-10. These findings suggest that serotonin and IL-10 have the potential to reduce blood viscosity in pregnant women with gestational diabetes and specific urinary incontinence, maintaining values similar to those in normoglycemic women's blood.

Ameliorating diabetes-associated atherosclerosis and diabetic nephropathy through modulation of soluble guanylate cyclase

Diabetes mellitus (DM) is an independent risk factor for micro- and macrovascular complications such as nephropathy and atherosclerosis respectively, which are the major causes of premature morbidity and mortality in Type 1 and Type 2 diabetic patients. Endothelial dysfunction is the critical first step of vascular disease and is characterized by reduced bioavailability of the essential endothelial vasodilator, nitric oxide (NO), coupled with an elevation in inflammation and oxidative stress. A novel pathway to bolster NO activity is to upregulate soluble guanylate cyclase (sGC), an enzyme responsible for mediating the protective actions of NO. Two classes of sGC modulators exist, activators and stimulators, with differing sensitivity to oxidative stress. In this study, we investigated the therapeutic effects of the sGC stimulator BAY 41-2272 (Bay 41) and the sGC activator BAY 60-2770 (Bay 60) on endpoints of atherosclerosis and renal disease as well as inflammation and oxidative stress in diabetic Apolipoprotein E knockout (ApoE-/-) mice. We hypothesized that under oxidative conditions known to accompany diabetes, sGC activation might be more efficacious than sGC stimulation in limiting diabetic vascular complications. We demonstrate that Bay 60 not only significantly decreased nitrotyrosine staining (P < 0.01) and F4/80 positive cells by 75% (P < 0.05), but it also significantly reduced total plaque area (P < 0.05) and improved endothelial function (P < 0.01). Our data suggest an important anti-atherogenic role for Bay 60 accompanied by reduced oxidative stress and inflammation under diabetic settings. Treatment with the stimulator Bay 41, on the other hand, had minimal effects or caused no changes with respect to cardiovascular or renal pathology. In the kidneys, treatment with Bay 60 significantly lessened urinary albuminuria, mesangial expansion and nitrotyrosine staining under diabetic conditions. In summary, our head-to-head comparator is the first preclinical study to show that a sGC activator is more efficacious than a sGC stimulator for the treatment of diabetes-associated vascular and renal complications.

ERK-containing microparticles from a diabetic mouse induce endothelial dysfunction

Endothelial dysfunction is a hallmark of diabetic vascular complications. Microparticles (MPs) are small vesicles shed from the surface of blood and vascular cells that act as stimuli and during apoptosis. Circulating MPs of diabetic rats have been shown to induce endothelial dysfunction. However, the underlying mechanisms require further study. In this study, we investigated how MPs from diabetic mice affect endothelial function. MPs were collected from streptozotocin-induced diabetic mice and Institute of Cancer Research (ICR) mice as controls. The levels of MPs were assessed and characterized by flow cytometry, enzyme-linked immunosorbent assay and dot blotting. Normal mice aortas were incubated with MPs and expressions of enzymes and vascular relaxation were analyzed. We found that (1) circulating MPs level increased in diabetic mice; (2) MPs impaired endothelial-dependent relaxation in mice aorta, but diabetic mice-derived MPs (diabetes mellitus (DM) MPs) were easier to attach to the endothelial cells than were control MPs; (3) DM MPs had more extracellular signal-regulated kinase (ERK)1/2 than did control mice-derived MPs, and they induced ERK1/2 activation in mice aortas; (4) DM MPs decreased endothelial nitric oxide synthase (eNOS) in mice aortas, and eNOS was emitted from endothelial cells to blood in the shape of endothelial MPs. DM MPs significantly altered endothelial function by activation of ERK1/2, which might provide a therapeutic target for diabetic vascular complications.

Novel links among peroxiredoxins, endothelial dysfunction, and severity of atherosclerosis in type 2 diabetic patients with peripheral atherosclerotic disease

Peroxiredoxins, a group of antioxidant protein enzymes (PRDX1 to 6), are reported as antiatherogenic factors in animals; however, human studies are lacking. The present work aims to provide baseline data regarding the phenotype of PRDX1, 2, 4, and 6 in diabetic patients with peripheral atherosclerosis disease (PAD) and their relation to endothelial dysfunction (ED) and disease severity. Plasma levels of PRDX1, 2, 4, and 6 and markers of endothelial dysfunction (ICAM-1 and VCAM-1) were measured using ELISA in 55 type 2 diabetic patients having PAD and 25 healthy subjects. Ankle-brachial index (ABI), body mass index (BMI), triglycerides (TG), total cholesterol, HbA1c, and insulin resistance (HOMA IR) were measured. PRDX1, 2, 4, and 6 levels were significantly higher in patients compared to controls (PRDX1 21.9 ± 5.71 vs 16.8 ± 3.9 ng/ml, P < 0.001, PRDX2 36.5 ± 14.83 vs 20.4 ± 8.61 ng/ml, P < 0.001, PRDX4 3,840 ± 1,440 vs 2,696 ± 1,972 pg/ml, P < 0.005, PRDX6 311 ± 110 vs 287.9 ± 114 pg/ml, P < 0.05). PRDX1 and PRDX4 correlated negatively with ABI (r = -0.273, P < 0.05 and r = -0.28, P < 0.05, respectively), while PRDX1 and PRDX2 correlated positively with HOMA/IR and TG (r = 0.276, P < 0.01 and r = 0.295, P < 0.01, respectively). ICAM-1 was associated with PRDX2 and log PRDX6 (r = 0.345, P = 0.0037 and r = 0.344, P = 0.0038). Our results provide strong links among PRDXs, ED, and severity of PAD in diabetic patients which warrants further evaluation to clarify whether high circulating levels of PRDXs are a consequence of chronic atherosclerotic disease or a predisposing factor for later cardiovascular events.

Effects of Momordica charantia L. on the blood rheological properties in diabetic patients

An evaluation of the rheological properties and the effects of Momordica. charantia L. (M. charantia) nanoparticles and polyethylene glycol (PEG) microspheres adsorbed with M. charantia nanoparticles on the blood of hyperglycemic patients is presented. Blood samples were collected according to glycemic status: normoglycemic (N = 56) and hyperglycemic (N = 26). General and hematological characteristics were determined. Blood rheological parameters were determined at room temperature and under a temperature scan. We determined the effects on whole blood viscosity of treatment with an extract of M. charantia, PEG, or PEG microspheres adsorbed with plant extract. The viscosity of the blood of hyperglycemic patients is greater than that of normoglycemic patients. Nanoparticles of M. charantia extracts lowered blood viscosity at equivalent rates in normo- and hyperglycemic individuals. PEG microspheres did not reduce blood viscosity in hyperglycemic individuals. However, PEG microspheres adsorbed with nanofraction extracts of M. charantia reduced blood viscosity. These data suggest that the effects of diabetes on the viscosity of the blood should be considered. The use of a nanoparticles extract of M. charantia and its adsorption on PEG microspheres may represent an alternative for the control and treatment of blood disorders in diabetic patients.

Targeting endothelial dysfunction in vascular complications associated with diabetes

Cardiovascular complications associated with diabetes remain a significant health issue in westernized societies. Overwhelming evidence from clinical and laboratory investigations have demonstrated that these cardiovascular complications are initiated by a dysfunctional vascular endothelium. Indeed, endothelial dysfunction is one of the key events that occur during diabetes, leading to the acceleration of cardiovascular mortality and morbidity. In a diabetic milieu, endothelial dysfunction occurs as a result of attenuated production of endothelial derived nitric oxide (EDNO) and augmented levels of reactive oxygen species (ROS). Thus, in this review, we discuss novel therapeutic targets that either upregulate EDNO production or increase antioxidant enzyme capacity in an effort to limit oxidative stress and restore endothelial function. In particular, endogenous signaling molecules that positively modulate EDNO synthesis and mimetics of endogenous antioxidant enzymes will be highlighted. Consequently, manipulation of these unique targets, either alone or in combination, may represent a novel strategy to confer vascular protection, with the ultimate goal of improved outcomes for diabetes-associated vascular complications.

Role of brainstem thyrotropin-releasing hormone-triggered sympathetic overactivation in cardiovascular mortality in type 2 diabetic Goto-Kakizaki rats

Sympathetic hyperactivity has an important role in cardiovascular mortality in patients with type 2 diabetes (T2D). Thyrotropin-releasing hormone (TRH)-containing fibers innervate autonomic motor and premotor nuclei of the brainstem and spinal cord that regulate cardiovascular functions. We compared cardiovascular responses to application of TRH-analog in the brainstem of Wistar and T2D Goto-Kakizaki (GK) rats. GK rats exhibited basal systolic hypertension (152±2 mm Hg) and had a significantly potentiated, dose-related hypertensive response to intracisternal (i.c.) injection of the TRH-analog RX77368 (10-60 ng). In GK rats only, i.c. RX77368 (30-60 ng) markedly increased heart rate (HR; +88 b.p.m.) and induced acute cardiac mortality (100%), concurrent with extreme hyperglycemia (>26 mmol l(-1)), increased plasma H(2)O(2) and 8-isoprostane, and enhanced heart expression of NADPH oxidase 4 and vascular cell adhesion molecule-1 mRNAs. GK rats also had elevated basal plasma epinephrine, higher adrenal gene expression of tyrosine hydroxylase and dopamine β-hydroxylase (DβH), and greater plasma catecholamine and adrenal DβH responses to i.c. TRH-analog, compared with Wistar rats. In GK rats, hexamethonium blocked i.c. RX77368-induced hypertensive and tachycardic responses, and reduced mortality by 86%, whereas phentolamine abolished the hypertensive response but enhanced tachycardia (+160 b.p.m.), and reduced mortality by 50%. The angiotensin II type 1 receptor antagonist irbesartan prevented i.c. RX77368-induced increases in blood pressure, HR and mortality. In conclusion, sympathetic overactivation triggered by brainstem TRH contributes to the mechanism of cardiovascular morbidity and mortality in T2D, which involves heightened cardiac inflammation and peripheral oxidative stress responses to sympathetic drive, and a mediating role of the renin-angiotensin system.

Angiogenic peptides improve blood flow and promote capillary growth in a diabetic and ischaemic mouse model

OBJECTIVES

It is a common clinical observation that collateral vessel development is impaired in diabetic patients with ischaemic vascular diseases. Consequently, alternative revascularisation strategies in diabetic patients are needed. This study presents the effect and mechanism of new peptide therapeutic angiogenesis in an ischaemic and diabetic mouse model.

DESIGN

Streptozocin-injected mice that had undergone hind-limb ischaemia were treated with angiogenic peptides. Blood flow restoration was calculated by laser Doppler imager and corroborated by histological section. For the mechanism study, endothelial cells were exposed to hypoxia and high glucose concentrations to study the effect of the peptides on proliferation and anti-apoptosis.

RESULTS

The peptides significantly restored blood perfusion 21 days after surgery in the diabetic mice (p < 0.01) by neo-vascularisation, corroborated by an increase in capillary density. In addition, the peptides induced the proliferation of hypoxic endothelial cells (p < 0.01) and protected the cells from apoptosis in high glucose cultures.

CONCLUSIONS

This is the first approach for treatment of ischaemic vascular disease with peptides in a diabetic mouse model.

Occupational therapy in diabetic care-areas of need perceived by older adults with diabetes

This study explored the perception of older adults with diabetes regarding the areas of service considered helpful to their daily activities and routines. A survey questionnaire was designed and given to 52 community-dwelling older adults with diabetes. Results showed that cholesterol control, managing blood sugar, foot care, fatigue management and pacing, and pain management/reduction were the areas of most concern that deserve services. The findings suggest that, in providing holistic client-centered interventions to individuals with diabetes, occupational therapists need to be able to prioritize clients' concerns and help them incorporate diabetes management into their routines and lifestyle.