Contribution of insulin resistance to vascular dysfunction

Association between metabolic score for insulin resistance (METS-IR) and hypertension: a cross-sectional study based on NHANES 2007-2018

BACKGROUND

Insulin resistance (IR) reduces insulin efficacy and heightens the danger of cardiovascular diseases including hypertension. The Metabolic Score for Insulin Resistance (METS-IR), which is based on triglyceride (TG) and high-density lipoprotein cholesterol (HDL-C), body mass index (BMI), and fasting glucose levels, provides a simpler way to assess IR. As the hypertension's prevalence increases, particularly in those with metabolic disorders, exploring the relationship between hypertension and METS-IR has become crucial.

METHODS

16,310 individuals from the 2007-2018 National Health and Nutrition Examination Survey dataset was included. Hypertension was defined by asking participants about their medical history and blood pressure measurements. METS-IR was calculated as follows: ln([ HDL-C (mg/dL)] × [2 × fasting glucose (mg/dL)] + TG (mg/dL) × BMI (kg/m2)). The study adjusted for covariates like sex; age; race; poverty-income ratio; marital status; educational background; total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), and serum creatinine levels; smoking; stroke; alcohol consumption; diabetes; and coronary heart disease (CHD). This study was conducted using a multi-factor regression model.

RESULTS

This research demonstrated a significant positive relationship between hypertension and METS-IR. Each 1-unit rise in METS-IR corresponds to a 3% higher chance of hypertension (odds ratio [OR], 1.03; 95% confidence interval [CI], 1.03-1.04). In model 3, METS-IR exhibited a notable correlation with hypertension (OR, 3.31; 95% CI, 2.64-4.14; P < 0.001). A threshold effect analysis demonstrated a nonlinear association. Finally, subgroup analyses supported the stability of the relationship between METS-IR and factors such as sex, race, alcohol consumption, CHD, smoking, and stroke (P > 0.05).

CONCLUSIONS

METS-IR showed a strong relationship with hypertension and may be an important marker for evaluating metabolic health and the early hypertension danger.

PCSK9 Expression in Vascular Smooth Muscle Cells: Role of Insulin Resistance and High Glucose

Beyond the regulation of cholesterol metabolism, a number of extrahepatic functions of proprotein convertase subtilisin/kexin type 9 (PCSK9) have been increasingly identified. The main purpose of this study was to verify whether PCSK9 expression in vascular smooth muscle cells (VSMC) is influenced by insulin resistance and high glucose (HG). In cultured rat aortic VSMC from lean insulin-sensitive Zucker rats (LZRs) and obese insulin-resistant Zucker rats (OZRs), a classical animal model of insulin resistance, we evaluated PCSK9 expression with or without the monoclonal antibodies against PCSK9 Alirocumab and Evolocumab or the synthetic PCSK9-binding peptide PEP 2-8. Effects and molecular mechanisms underlying altered PCSK9 expression were evaluated by proliferation and migration assay, reactive oxygen species (ROS) production, and involvement of PKC, NADPH-oxidase, MAPK/ERK-1/2 pathway activation. As a result, we found that, in comparison with LZR, VSMC from OZR showed basal PCSK9 overexpression mitigated by Alirocumab, Evolocumab, PEP 2-8, and the inhibitors of PKC, NADPH-oxidase, and MAPK. The finding of PCSK9 upregulation in VSMC from OZR paralleled with increased ROS production, proliferation, and migration. HG increased PCSK9 expression in VSMC from LZR, but not in OZR, via oxidative stress and with effects reduced by PCSK9 inhibitors. These findings suggest that a dysregulation of PCSK9 in VSMC could be involved in vascular damage in metabolic disorders, such as obesity and diabetes.

Leveraging IgG N-glycosylation to infer the causality between T2D and hypertension

BACKGROUND

Observational studies demonstrated a bidirectional association between type 2 diabetes (T2D) and hypertension, whereas Mendelian randomization (MR) analyses supported the causality from T2D to hypertension but not causal from hypertension to T2D. We previously found that IgG N-glycosylation is associated with both T2D and hypertension, and thus IgG N-glycosylation might link the causality between them.

METHODS

We carried out a genome-wide association study (GWAS) to identify IgG N-glycosylation-quantitative-trait loci (QTLs) integrating GWAS for T2D and hypertension and then performed bidirectional univariable and multivariable MR analyses to infer the causal association among them. The inverse-variance-weighted (IVW) analysis was performed as the primary analysis, followed by some sensitivity analyses to explore the stability of the results.

RESULTS

Six putatively causal IgG N-glycans for T2D and four for hypertension were identified in the IVW method. Genetically predicted T2D increased the risk of hypertension (odds ratio [OR] = 1.177, 95% confidence interval (95% CI) = 1.037-1.338, P = 0.012) and vice versa (OR = 1.391, 95% CI = 1.081-1.790, P = 0.010). Multivariable MR showed that T2D remained at risk effect with hypertension ([OR] = 1.229, 95% CI = 1.140-1.325, P = 7.817 × 10^-8) after conditioning on T2D-related IgG-glycans. Conversely, hypertension was associated with higher T2D risk (OR = 1.287, 95% CI = 1.107-1.497, P = 0.001) after adjusting for related IgG-glycans. No evidence of horizontal pleiotropy was observed, as MR‒Egger regression provided P values for intercept > 0.05.

CONCLUSION

Our study validated the mutual causality between T2D and hypertension from the perspective of IgG N-glycosylation, further validating the "common soil" hypothesis underlying the pathogenesis of T2D and hypertension.

Association of β-cell function and cognitive impairment in patients with abnormal glucose metabolism

Background

Insulin has been demonstrated to play an important role in the occurrence and development of Alzheimer’s disease, especially in those with diabetes. β cells are important insulin-producing cells in human pancreas. This study aimed to investigate the association between β-cell dysfunction and cognitive impairment among patients over 40-year-old with abnormal glucose metabolism in Chinese rural communities.

Methods

A sample of 592 participants aged 40 years or older from the China National Stroke Prevention Project (CSPP) between 2015 and 2017 were enrolled in this study. Abnormal glucose metabolism was defined when hemoglobin Alc ≥ 5.7%. Cognitive function was assessed by the Beijing edition of the Montreal Cognitive Assessment scale. Homeostasis assessment of β-cell function was performed and classified into 4 groups according to the quartiles. A lower value of HOMA-β indicated a worse condition of β-cell function. Multivariate logistic regression was used to analyze the association between β-cell function and cognitive impairment.

Results

In a total of 592 patients with abnormal glucose metabolism, the average age was 60.20 ± 7.63 years and 60.1% patients had cognitive impairment. After adjusting for all potential risk factors, we found the first quartile of β-cell function was significantly associated with cognitive impairment (OR: 2.27, 95%CI: 1.32–3.92), especially at the domains of language (OR: 1.64, 95%CI: 1.01–2.65) and abstraction (OR: 2.29, 95%CI: 1.46–3.58).

Conclusions

Our study showed that worse β-cell function is associated with cognitive impairment of people over 40-year-old with abnormal glucose metabolism in Chinese rural communities, especially in the cognitive domains of abstraction and language.

Single serine on TSC2 exerts biased control over mTORC1 activation mediated by ERK1/2 but not Akt

Both ERK1/2 and Akt kinases activate mTORC1, but only the former is bidirectionally regulated by the status of serine S1364 on TSC2 that confers input-selective mTORC1 amplification or attenuation.

Tuberous sclerosis complex-2 (TSC2) negatively regulates mammalian target of rapamycin complex 1 (mTORC1), and its activity is reduced by protein kinase B (Akt) and extracellular response kinase (ERK1/2) phosphorylation to activate mTORC1. Serine 1364 (human) on TSC2 bidirectionally modifies mTORC1 activation by pathological growth factors or hemodynamic stress but has no impact on resting activity. We now show this modification biases to ERK1/2 but not Akt-dependent TSC2-mTORC1 activation. Endothelin-1–stimulated mTORC1 requires ERK1/2 activation and is bidirectionally modified by phospho-mimetic (S1364E) or phospho-silenced (S1364A) mutations. However, mTORC1 activation by Akt-dependent stimuli (insulin or PDGF) is unaltered by S1364 modification. Thrombin stimulates both pathways, yet only the ERK1/2 component is modulated by S1364. S1364 also has negligible impact on mTORC1 regulation by energy or nutrient status. In vivo, diet-induced obesity, diabetes, and fatty liver couple to Akt activation and are also unaltered by TSC2 S1364 mutations. This contrasts to prior reports showing a marked impact of both on pathological pressure-stress. Thus, S1364 provides ERK1/2-selective mTORC1 control and a genetic means to modify pathological versus physiological mTOR stimuli.

A novel inflammatory signaling pathway in patients with slow coronary flow: NF-κB/IL-1β/nitric oxide

PURPOSE

The slow coronary flow (SCF) was identified as delayed opacification of epicardial coronary arteries in the absence of stenotic lesion. Metabolic syndrome (MetS), oxidative stress, and inflammation may be possible known insulting factors for the pathogenesis of SCF. This investigation aimed to assess the relationship between some inflammatory markers, oxidative stress parameters and MetS components with SCF phenomenon.

METHODS

A total of 35 patients with SCF and 35 subjects with normal coronary flow (NCF) were included in the study. We assessed some inflammatory markers (IL-1β, IL-18, TNF-α, and NF-κB mRNA expression in peripheral blood mononuclear cells (PBMCs)). Moreover, blood samples of the participants were tested for total antioxidant capacity (TAC), glutathione peroxidase (GPX) and nitric oxide (NO) levels using enzyme-linked immunosorbent assay (ELISA). Diagnosis of MetS was based on the National Cholesterol Education Program's Adult Treatment Panel III report (ATPIII) criteria, 2005. Diagnostic criteria for coronary flow rates of all subjects were documented by thrombolysis in myocardial infarction (TIMI) frame count method.

RESULTS

SCF patients had significantly higher prevalence of MetS (46%, p = 0.048).We found that the level of TAC was significantly higher in the NCF group (p = 0.006). Furthermore, the NO concentration was significantly lower in SCF groups (p = 0.001). A significant incremental difference was detected in IL-1β (fold change 2.82 ± 0.31, p < 0.05) and NF-κB (fold change 4.62 ± 0.32, p < 0.05) mRNA expression in the SCF group when compared with its level in the NCF group. Furthermore, according to logistic regression analysis, there were significant associations between IL-1β, NF-κB expression levels and the incidence of SCF (p < 0.05).

CONCLUSION

Based on the findings of this study, the pathogenesis of the SCF phenomenon may be closely associated with metabolic syndrome and inflammation. The NF-κB/IL-1β/nitric oxide & MetS signaling pathway might be considered as potential therapeutic targets in the management of SCF patients but further researches is required to guarantee these findings.

Endothelial dysfunction and transcriptome aberration in mouse aortas induced by black phosphorus quantum dots and nanosheets

Black phosphorus (BP) nanomaterials have shown great potential in versatile applications including biomedicine and potentially interact with vessel walls following intravenous injection in biomedical usage or environmental exposure. However, it remains unknown whether the exposure to BP nanomaterials induces alterations of the endothelium and further vascular injury. Herein, the endothelial function of human umbilical vein endothelial cells (HUVECs) and the structure and transcriptome of C57BL/6 mouse aortas are evaluated after the exposure to BP quantum dots (BPQDs) and nanosheets (BPNSs). BPNSs with irregular shapes and larger lateral size are more prone to inhibit in vitro angiogenesis at non-cytotoxic concentrations and markedly trigger platelet adhesion to HUVECs compared to BPQDs. Decreased nitric oxide (NO) production resulting from endothelial NO synthase (eNOS) dysregulation is involved in the BP-induced endothelial dysfunction. Both BPQDs and BPNSs at 0.8 and 6.4 μg mL-1 inhibit eNOS enzymatic activity through dephosphorylation of eNOS-Ser1177 and phosphorylation of eNOS-Thr495, but unlike BPQDs, BPNSs also downregulate eNOS expression. Despite no pathological damage in the structure of mouse aortas, BPQDs and BPNSs trigger aberration of aortic transcriptome involved in vasoconstriction abnormality, metabolic disturbance, and immune perturbation. This study demonstrates the adverse effect of BP nanomaterials on vasculature, and suggests that the morphological attribute of BP plays a crucial role in the vascular risks.

Dynamic changes in aortic stiffness after substantial weight loss by laparoscopic sleeve gastrectomy in patients with obesity: a 1-year follow-up study

Arterial stiffness has been identified as a powerful and independent risk factor for cardiovascular disease. Obesity is associated with an increased risk of aortic stiffness (AS) and adverse cardiovascular events. Herein, we aimed to evaluate the effects of weight loss after laparoscopic sleeve gastrectomy (LSG) on AS in individuals with morbid obesity by using the transthoracic echocardiography (TTE).A total of 53 patients with obesity (17 males, 36 females) who underwent LSG and did not have any known heart disease were included in the study. The AS parameters were measured with TTE. The demographic and echocardiographic data of the patients were studied before, at 1 month and 12 months after surgery.The mean age of the study group was 34.41±11.62, 68% of whom were female. There were no significant differences in terms of the standard echocardiography and Doppler measurements as compared with preoperative values (all p>0.05). When the elastic parameters of the aorta were compared, no significant differences were detected regarding aortic strain (%) ((16.28±4.11) vs (16.68±4.56), p=(0.998)), distensibility (cm²/dyn) ((6.74±1.78) vs (7.03±2.31), p=(0.997)) and Aortic Stiffness Index values ((10.73±3.84) vs (10.63±3.34), p=0.998) between baseline and first month after surgery. In the 12-month follow-up, it was determined that the aortic strain ((16.28±4.11) vs (22.74±5.79), p≤0.001) and distensibility ((6.74±1.78) vs (10.34±3.059), p<0.001)) values increased at significant levels.Weight loss by LSG improves arterial stiffness parameters in patients with obesity over a 1-year follow-up.

Mechanism Study of the Protective Effects of Sodium Tanshinone IIA Sulfonate Against Atorvastatin-Induced Cerebral Hemorrhage in Zebrafish: Transcriptome Analysis

Hemorrhage stroke is a severe vascular disease of the brain with a high mortality rate in humans. Salvia miltiorrhiza Bunge (Danshen) is a well-known Chinese Materia Medica for treating cerebral vascular and cardiovascular diseases in traditional Chinese medicine. Sodium tanshinone IIA sulfonate (STS) is a water-soluble derivative of tanshinone IIA, which is the main active ingredient of Danshen. In our previous study, we established a zebrafish model of cerebral hemorrhage and found that STS dramatically decreased both the hemorrhage rate and hemorrhage area, although the underlying mechanism was not fully elucidated. We conducted a transcriptome analysis of the protective effect of STS against atorvastatin (Ator)-induced cerebral hemorrhage in zebrafish using RNA-seq technology. RNA-seq revealed 207 DEGs between the Ator-treated group and control group; the expression levels of 53 DEGs between the Ator-treated group and control group were reversed between the STS + Ator-treated group and Ator-treated group. GO enrichment analysis indicated that these 53 DEGs encode proteins with roles in hemoglobin complexes, oxygen carrier activity and oxygen binding, etc. KEGG analysis suggested that these 53 DEGs were most enriched in three items, namely, porphyrin and chlorophyll metabolism, ferroptosis, and the HIF-1 signaling pathway. The PPI network analysis identified 12 hub genes, and we further verified that Ator elevated the mRNA expression levels of hemoglobin (hbae1.3, hbae3, hbae5, hbbe2, and hbbe3), carbonic anhydrase (cahz), HIF-1 (hif1al2) and Na+/H+ exchanger (slc4a1a and slc9a1) genes, while STS significantly suppressed these genes. In addition, we found that pharmacological inhibition of PI3K/Akt, MAPKs, and mTOR signaling pathways by specific inhibitors partially attenuated the protective effect of STS against Ator-induced cerebral hemorrhage in zebrafish, regardless of mTOR inhibition. We concluded that hemoglobin, carbonic anhydrase, Na+/H+ exchanger and HIF-1 genes might be potential biomarkers of Ator-induced cerebral hemorrhage in zebrafish, as well as pharmacological targets of STS. Moreover, HIF-1 and its regulators, i.e., the PI3K/Akt and MAPK signaling pathways, were involved in the protective effect of STS against Ator-induced cerebral hemorrhage. This study also provided evidence of biomarkers involved in hemorrhage stroke and improved understanding of the effects of HMG-COA reductase inhibition on vascular permeability and cerebral hemorrhage.

Study of correlations between metabolic risk factors, PWV and hypertension in college students

Objective: Obesity, dyslipidemia and diabetes have been recognized as risk factors of hypertension in the general population. This study focused on college students and correlations between serum lipids, serum uric acid, fasting plasma glucose, serum creatinine, body mass index, brachial-ankle pulse wave velocity and hypertension. The results suggested that there was no relevance between serum lipids and hypertension. However, it came out that hypertension is associated with normal fasting plasma glucose, BMI (thinness and normal weight), normal serum creatinine. Methods: A total of 5185 students were enrolled, and their blood pressure, height and weight were measured. 285 of the students were selected to take physical examinations including serum uric acid, total cholesterol, low-density lipoprotein cholesterol, triglyceride, high-density lipoprotein cholesterol, fasting plasma glucose, serum creatinine, blood urea nitrogen, ankle-brachial index and brachial-ankle pulse wave velocity measured. Results: The values of systolic blood pressure(SBP), diastolic blood pressure(DBP), serum uric acid, fasting plasma glucose(FPG), serum creatinine, body mass index(BMI), and brachial-ankle pulse wave velocity(baPWV) were higher in hypertension group than those in non-hypertension group (P < .001, <0.001, <0.001, = 0.009, = 0.07, <0.001, <0.001, respectively). Logistic regression showed correlations between hypertension and hyperuricemia (OR = 2.975, 95%CI: 1.672-5.291), obesity (OR = 2.814, 95%CI: 1.297-6.105), fasting plasma glucose (OR = 2.184, 95%CI: 1.090-4.378) and brachial-ankle pulse wave velocity (OR = 1.005, 95%CI: 1.003-1.007). The AUC was 0.786 (95%CI: 0.729-0.842, P < .0001). We can draw a conclusion that hyperuricemia, obesity, fasting plasma glucose and brachial-ankle pulse wave velocity, listed in descending order of influence, are risk factors for hypertension in college students.

Influence of Cardiometabolic Risk Factors on Platelet Function

Platelets are key players in the thrombotic processes. The alterations of platelet function due to the occurrence of metabolic disorders contribute to an increased trend to thrombus formation and arterial occlusion, thus playing a major role in the increased risk of atherothrombotic events in patients with cardiometabolic risk factors. Several lines of evidence strongly correlate metabolic disorders such as obesity, a classical condition of insulin resistance, dyslipidemia, and impaired glucose homeostasis with cardiovascular diseases. The presence of these clinical features together with hypertension and disturbed microhemorrheology are responsible for the prothrombotic tendency due, at least partially, to platelet hyperaggregability and hyperactivation. A number of clinical platelet markers are elevated in obese and type 2 diabetes (T2DM) patients, including the mean platelet volume, circulating levels of platelet microparticles, oxidation products, platelet-derived soluble P-selectin and CD40L, thus contributing to an intersection between obesity, inflammation, and thrombosis. In subjects with insulin resistance and T2DM some defects depend on a reduced sensitivity to mediators—such as nitric oxide and prostacyclin—playing a physiological role in the control of platelet aggregability. Furthermore, other alterations occur only in relation to hyperglycemia. In this review, the main cardiometabolic risk factors, all components of metabolic syndrome involved in the prothrombotic tendency, will be taken into account considering some of the mechanisms involved in the alterations of platelet function resulting in platelet hyperactivation.

The Postprandial Appearance of Features of Cardiometabolic Risk: Acute Induction and Prevention by Nutrients and Other Dietary Substances

The purpose of this review is to provide an overview of diets, food, and food components that affect postprandial inflammation, endothelial function, and oxidative stress, which are related to cardiometabolic risk. A high-energy meal, rich in saturated fat and sugars, induces the transient appearance of a series of metabolic, signaling and physiological dysregulations or dysfunctions, including oxidative stress, low-grade inflammation, and endothelial dysfunction, which are directly related to the amplitude of postprandial plasma triglycerides and glucose. Low-grade inflammation and endothelial dysfunction are also known to cluster together with insulin resistance, a third risk factor for cardiovascular diseases (CVD) and type-II diabetes, thus making a considerable contribution to cardiometabolic risk. Because of the marked relevance of the postprandial model to nutritional pathophysiology, many studies have investigated whether adding various nutrients and other substances to such a challenge meal might mitigate the onset of these adverse effects. Some foods (e.g., nuts, berries, and citrus), nutrients (e.g., l-arginine), and other substances (various polyphenols) have been widely studied. Reports of favorable effects in the postprandial state have concerned plasma markers for systemic or vascular pro-inflammatory conditions, the activation of inflammatory pathways in plasma monocytes, vascular endothelial function (mostly assessed using physiological criteria), and postprandial oxidative stress. Although the literature is fragmented, this topic warrants further study using multiple endpoints and markers to investigate whether the interesting candidates identified might prevent or limit the postprandial appearance of critical features of cardiometabolic risk.

Hypertension and Diabetes Mellitus: Coprediction and Time Trajectories

Type 2 diabetes mellitus and hypertension overlap in the population. In many subjects, development of diabetes mellitus is characterized by a relatively rapid increase in plasma glucose values. Whether a similar phenomenon occurs during the development of hypertension is not known. We analyzed the pattern of blood pressure (BP) changes during the development of hypertension in patients with or without diabetes mellitus using data from the MCDS (Mexico City Diabetes Study; a population-based study of diabetes mellitus in Hispanic whites) and in the FOS (Framingham Offspring Study, a community-based study in non-Hispanic whites) during a 7-year follow-up. Diabetes mellitus at baseline was a significant predictor of incident hypertension (in FOS, odds ratio, 3.14; 95% confidence interval, 2.17-4.54) independently of sex, age, body mass index, and familial diabetes mellitus. Conversely, hypertension at baseline was an independent predictor of incident diabetes mellitus (in FOS, odds ratio, 3.33; 95% CI, 2.50-4.44). In >60% of the converters, progression from normotension to hypertension was characterized by a steep increase in BP values, averaging 20 mm Hg for systolic BP within 3.5 years (in MCDS). In comparison with the nonconverters group, hypertension and diabetes mellitus converters shared a metabolic syndrome phenotype (hyperinsulinemia, higher body mass index, waist girth, BP, heart rate and pulse pressure, and dyslipidemia). Overall, results were similar in the 2 ethnic groups. We conclude that (1) development of hypertension and diabetes mellitus track each other over time, (2) transition from normotension to hypertension is characterized by a sharp increase in BP values, and (3) insulin resistance is one common feature of both prediabetes and prehypertension and an antecedent of progression to 2 respective disease states.

Quercetin improves endothelial function in diabetic rats through inhibition of endoplasmic reticulum stress-mediated oxidative stress

Endoplasmic reticulum (ER) stress attributes a crucial role in diabetes-induced endothelial dysfunction. The present study investigated the effects of quercetin, a potent antioxidant on the attenuation of ER stress-modulated endothelial dysfunction in streptozotocin (STZ)-induced diabetic rats. Oral administration of quercetin for six weeks to diabetic rats dose-dependently reduced the blood glucose levels and improved insulin secretion. Histopathological examination of pancreatic tissues in diabetic rats showed pathological changes such as shrunken islets, reduction in islet area and distorted β-cells, which were found to be restored by quercetin treatment. In addition, quercetin reduced the pancreatic ER stress-induced endothelial dysfunction as assessed by immunohistochemical analysis of C/ERB homologous protein (CHOP) and endothelin-1 (ET-1). Moreover, quercetin administration progressively increased the expression of vascular endothelial growth factor (VEGF) and its receptor, VEGFR2 in diabetes rats. Quercetin-mediated decrease in the nitric oxide (NO∙) and cyclic 3',5'- guanosine monophosphate (cGMP) levels were also observed in the diabetic rats. Quercetin treatment reduced the lipid peroxidation in the diabetic rats, meanwhile increased the total antioxidant capacity in the pancreas from diabetic rats. Altogether, these results demonstrated the vasoprotective effect of quercetin against STZ-induced ER stress in the pancreas of diabetic rats.

Tendinopathy in diabetes mellitus patients-Epidemiology, pathogenesis, and management

Chronic tendinopathy is a frequent and disabling musculo-skeletal problem affecting the athletic and general populations. The affected tendon is presented with local tenderness, swelling, and pain which restrict the activity of the individual. Tendon degeneration reduces the mechanical strength and predisposes it to rupture. The pathogenic mechanisms of chronic tendinopathy are not fully understood and several major non-mutually exclusive hypotheses including activation of the hypoxia-apoptosis-pro-inflammatory cytokines cascade, neurovascular ingrowth, increased production of neuromediators, and erroneous stem cell differentiation have been proposed. Many intrinsic and extrinsic risk/causative factors can predispose to the development of tendinopathy. Among them, diabetes mellitus is an important risk/causative factor. This review aims to appraise the current literature on the epidemiology and pathology of tendinopathy in diabetic patients. Systematic reviews were done to summarize the literature on (a) the association between diabetes mellitus and tendinopathy/tendon tears, (b) the pathological changes in tendon under diabetic or hyperglycemic conditions, and (c) the effects of diabetes mellitus or hyperglycemia on the outcomes of tendon healing. The potential mechanisms of diabetes mellitus in causing and exacerbating tendinopathy with reference to the major non-mutually exclusive hypotheses of the pathogenic mechanisms of chronic tendinopathy as reported in the literature are also discussed. Potential strategies for the management of tendinopathy in diabetic patients are presented.

Association of blood glucose level and hypertension in Elderly Chinese Subjects: a community based study

BACKGROUND

There is a scarcity of epidemiological researches examining the relationship between blood pressure (BP) and glucose level among older adults. The objective of the current study was to investigate the association of high BP and glucose level in elderly Chinese.

METHODS

A cross-sectional study of a population of 2092 Chinese individuals aged over 65 years was conducted. Multiple logistic analysis was used to explore the association between hypertension and hyperglycemia. Independent risk factors for systolic and diastolic BP were analyzed using stepwise linear regression.

RESULTS

Subjects in impaired fasting glucose group (IFG) (n = 144) and diabetes (n = 346), as compared with normal fasting glucose (NFG) (n = 1277), had a significant higher risk for hypertension, with odds ratios (ORs) of 1.81 (95 % CI, 1.39-2.35) (P = 0.000) and 1.40 (95 % CI, 1.09-1.80) (P = 0.009), respectively. Higher fasting plasma glucose (FPG) levels in the normal range were still significantly associated with a higher prevalence of hypertension in both genders, with ORs of 1.24 (95 % CI, 0.85-1.80), R (2) = 0.114, P = 0.023 in men and 1.61 (95 % CI, 1.12-2.30), R (2) = 0.082, P = 0.010 in women, respectively, when compared with lower FPG. Linear regression analysis revealed FPG was an independent factor of systolic and diastolic BP.

CONCLUSIONS

Our findings suggest that hyperglycemia as well as higher FPG within the normal range is associated with a higher prevalence of hypertension independent of other cardiovascular risk factors in elderly Chinese. Further studies are needed to explore the relationship between hyperglycemia and hypertension in a longitudinal setting.

Coordinated augmentation of NFAT and NOD signaling mediates proliferative VSMC phenotype switch under hyperinsulinemia

AIM

Although hyperglycemia has been demonstrated to play a significant role in the vascular disease associated with type 2 diabetes, the mechanisms underlying hyperinsulinemia mediated vascular dysfunction are not well understood. We have analyzed whether hyperinsulinemia could activate NFAT (Nuclear factor of activated T cells) signaling and thereby influence vascular smooth muscle cell (VSMC) migration and proliferation, a major event in the progression of atherosclerosis.

METHODS AND RESULTS

Human aortic VSMCs upon chronic insulin treatment exhibited increased expression of NFATc1 both at the mRNA and protein levels. The mechanistic role of NFAT in VSMC migration and proliferation was examined using 11R-VIVIT, a cell permeable NFAT specific inhibitor, where it reduced the insulin effect on VSMC, which was further substantiated by over expression or silencing of NFATc1gene (p < 0.05). This study also report for the first time the role of NFAT in NOD (Nucleotide oligomerization domain) mediated innate immune signaling and its significance in insulin effect on VSMCs. mRNA expression of NOD was up regulated when cells were treated with insulin or ligands whereas pretreatment with 11R-VIVIT reversed this effect (p < 0.05). Our study uphold the clinical significance as we observed an increased mRNA expression of NFATc1 in monocytes isolated from patients with type 2 diabetes which correlated positively with insulin resistance and glycemic load (p < 0.05).

DISCUSSION

This study suggests that targeted NFAT inhibition can be an effective strategy to coordinately quench insulin induced proliferative and inflammatory responses along with innate immunity alterations in vascular smooth muscle cells, which underlie atherosclerosis.

Impact of a lifestyle program on vascular insulin resistance in metabolic syndrome subjects: the RESOLVE study

CONTEXT AND OBJECTIVE

Impaired insulin-dependent vasodilation might contribute to microvascular dysfunction of metabolic syndrome (MetS). The aims of this study were to assess the insulin vasoreactivity in MetS, and to evaluate the effects of a lifestyle program. DESIGN, SETTING, PARTICIPANTS, AND OUTCOME MEASURES: Laser Doppler measurements were used to assess cutaneous blood flux (CBF) and flowmotion in response to iontophoresis of insulin and acetylcholine (ACh) in 38 MetS and 18 controls. Anthropometric, plasma insulin, glycemia, and inflammatory markers were measured. MetS subjects (n = 24) underwent a 6-month lifestyle intervention (M6) with a 3-week residential program (D21).

RESULTS

The absolute and relative peak insulin and ACh CBF were significantly higher in controls than in MetS subjects. Significant inverse correlations were found between peak insulin CBF and glycemia, insulin and glycated hemoglobin, active plasminogen activator inhibitor-1 (PAI-1), C-reactive protein (CRP), and IL-6. With respect to flowmotion, MetS subjects showed lower values in total spectrum CBF and in all its components (except respiratory one). At D21 and M6, peak insulin CBF increased and was no longer different from control values whereas peak ACh CBF did not change. From D21, all the different components and the total CBF spectrum became similar to the control values. The changes in peak insulin CBF and in endothelial component between M6 and baseline were inversely correlated with the change in CRP and PAI-1.

CONCLUSIONS

The local vasodilatory effects to insulin and its overall flowmotion are impaired in MetS subjects in relation to inflammation. The lifestyle intervention reversed this insulin-induced vascular dysfunction in parallel to decreased inflammation level.

Soluble DPP4 induces inflammation and proliferation of human smooth muscle cells via protease-activated receptor 2

DPP4 is an ubiquitously expressed cell-surface protease that is shedded to the circulation as soluble DPP4 (sDPP4). We recently identified sDPP4 as a novel adipokine potentially linking obesity to the metabolic syndrome. The aim of this study was to investigate direct effects of sDPP4 on human vascular smooth muscle cells (hVSMCs) and to identify responsible signaling pathways. Using physiological concentrations of sDPP4, we could observe a concentration-dependent activation of ERK1/2 (3-fold) after 6h, which remained stable for up to 24h. Additionally, sDPP4 treatment induced a 1.5-fold phosphorylation of the NF-κB subunit p65. In accordance with sDPP4-induced stress and inflammatory signaling, sDPP4 also stimulates hVSMC proliferation. Furthermore we could observe an increased expression and secretion of pro-inflammatory cytokines like interleukin (IL)-6, IL-8 and MCP-1 (2.5-, 2.4- and 1.5-fold, respectively) by the sDPP4 treatment. All direct effects of sDPP4 on signaling, proliferation and inflammation could completely be prevented by DPP4 inhibition. Bioinformatic analysis and signaling signature induced by sDPP4 suggest that sDPP4 might be an agonist for PAR2. After the silencing of PAR2, the sDPP4-induced ERK activation as well as the proliferation was totally abolished. Additionally, the sDPP4-induced upregulation of IL-6 and IL-8 could completely be prevented by the PAR2 silencing. In conclusion, we show for the first time that sDPP4 directly activates the MAPK and NF-κB signaling cascade involving PAR2 and resulting in the induction of inflammation and proliferation of hVSMC. Thus, our in vitro data might extend the current view of sDPP4 action and shed light on cardiovascular effects of DPP4-inhibitors.

Signal transduction in podocytes--spotlight on receptor tyrosine kinases

The mammalian kidney filtration barrier is a complex multicellular, multicomponent structure that maintains homeostasis by regulating electrolytes, acid-base balance, and blood pressure (via maintenance of salt and water balance). To perform these multiple functions, podocytes--an important component of the filtration apparatus--must process a series of intercellular signals. Integrating these signals with diverse cellular responses enables a coordinated response to various conditions. Although mature podocytes are terminally differentiated and cannot proliferate, they are able to respond to growth factors. It is possible that the initial response of podocytes to growth factors is beneficial and protective, and might include the induction of hypertrophic cell growth. However, extended and/or uncontrolled growth factor signalling might be maladaptive and could result in the induction of apoptosis and podocyte loss. Growth factors signal via the activation of receptor tyrosine kinases (RTKs) on their target cells and around a quarter of the 58 RTK family members that are encoded in the human genome have been identified in podocytes. Pharmacological inhibitors of many RTKs exist and are currently used in experimental and clinical cancer therapy. The identification of pathological RTK-mediated signal transduction pathways in podocytes could provide a starting point for the development of novel therapies for glomerular disorders.

Oleic acid increases synthesis and secretion of VEGF in rat vascular smooth muscle cells: role of oxidative stress and impairment in obesity

Obesity is characterized by poor collateral vessel formation, a process involving vascular endothelial growth factor (VEGF) action on vascular smooth muscle cells (VSMC). Free fatty acids are involved in the pathogenesis of obesity vascular complications, and we have aimed to clarify whether oleic acid (OA) enhances VEGF synthesis/secretion in VSMC, and whether this effect is impaired in obesity. In cultured aortic VSMC from lean and obese Zucker rats (LZR and OZR, respectively) we measured the influence of OA on VEGF-A synthesis/secretion, signaling molecules and reactive oxygen species (ROS). In VSMC from LZR we found the following: (a) OA increases VEGF-A synthesis/secretion by a mechanism blunted by inhibitors of Akt, mTOR, ERK-1/2, PKC-beta, NADPH-oxidase and mitochondrial electron transport chain complex; (b) OA activates the above mentioned signaling pathways and increases ROS; (c) OA-induced activation of PKC-beta enhances oxidative stress, which activates signaling pathways responsible for the increased VEGF synthesis/secretion. In VSMC from OZR, which present enhanced baseline oxidative stress, the above mentioned actions of OA on VEGF-A, signaling pathways and ROS are impaired: this impairment is reproduced in VSMC from LZR by incubation with hydrogen peroxide. Thus, in OZR chronically elevated oxidative stress causes a resistance to the action on VEGF that OA exerts in LZR by increasing ROS.

Lifestyle impact on meal-induced insulin sensitization in health and prediabetes: A focus on diet, antioxidants, and exercise interventions

The augmented whole-body glucose uptake response to insulin during the postprandial state is described as meal-induced insulin sensitization (MIS). MIS occurs when the presence of food in the upper gastrointestinal tract activates 2 feeding signals (activation of hepatic parasympathetic nerves and elevation of hepatic glutathione level), and causes insulin to release hepatic insulin sensitizing substance (HISS), which stimulates glucose uptake in skeletal muscle, heart, and kidneys. HISS action results in nutrient storage, primarily as glycogen. Impairment of HISS release results in the absence of meal-induced insulin sensitization (AMIS), which causes postprandial hyperglycemia and hyperinsulinemia, and chronically leads to the progression to a cluster of metabolic, vascular, and cardiac dysfunctions, which we refer to as components of the AMIS syndrome. Manipulation of the MIS process in health and in disease, by pharmacological and nonpharmacological interventions, is outlined in this review. High fat or sugar supplemented diet reduces MIS; exercise elevates MIS; and antioxidants protect MIS against reductions associated with diet and age.

The feto-placental endothelium in pregnancy pathologies

This review aims to provide a comprehensive summary of the aspects of endothelial and vascular dysfunction in the feto-placental vasculature occurring in pregnancy pathologies. This endothelium is continuous with the fetal circulation. Its function and potential dysfunction in pathologies will have a profound impact on fetal development. Gestational diabetes mellitus represents one of these pathologies, in which its associated metabolic derangements will alter feto-placental endothelial functions. These, in turn, may result in functional changes of the placenta, which may entail impaired fetal development. By contrast, changes in the feto-placental vasculature observed in cases of fetal growth restriction and preeclampsia may be causative (fetal growth restriction) or secondary (preeclampsia) for the pathology.

Diabetes and hypertension: the bad companions

High blood pressure is reported in over two-thirds of patients with type 2 diabetes, and its development coincides with the development of hyperglycaemia. Many pathophysiological mechanisms underlie this association. Of these mechanisms, insulin resistance in the nitric-oxide pathway; the stimulatory effect of hyperinsulinaemia on sympathetic drive, smooth muscle growth, and sodium-fluid retention; and the excitatory effect of hyperglycaemia on the renin-angiotensin-aldosterone system seem to be plausible. In patients with diabetes, hypertension confers an enhanced risk of cardiovascular disease. A blood pressure of lower than 140/85 mm Hg is a reasonable therapeutic goal in patients with type 2 diabetes according to clinical trial evidence. People with controlled diabetes have a similar cardiovascular risk to patients without diabetes but with hypertension. A renin-angiotensin system blocker combined with a thiazide-type diuretic might be the best initial antihypertensive regimen for most people with diabetes. In general, the positive effects of antihypertensive drugs on cardiovascular outcomes outweigh the negative effects of antihypertensive drugs on glucose metabolism.

Insulin regulates its own delivery to skeletal muscle by feed-forward actions on the vasculature

Insulin, at physiological concentrations, regulates the volume of microvasculature perfused within skeletal and cardiac muscle. It can also, by relaxing the larger resistance vessels, increase total muscle blood flow. Both of these effects require endothelial cell nitric oxide generation and smooth muscle cell relaxation, and each could increase delivery of insulin and nutrients to muscle. The capillary microvasculature possesses the greatest endothelial surface area of the body. Yet, whether insulin acts on the capillary endothelial cell is not known. Here, we review insulin's actions at each of three levels of the arterial vasculature as well as recent data suggesting that insulin can regulate a vesicular transport system within the endothelial cell. This latter action, if it occurs at the capillary level, could enhance insulin delivery to muscle interstitium and thereby complement insulin's actions on arteriolar endothelium to increase insulin delivery. We also review work that suggests that this action of insulin on vesicle transport depends on endothelial cell nitric oxide generation and that insulin's ability to regulate this vesicular transport system is impaired by inflammatory cytokines that provoke insulin resistance.

HISS, not insulin, causes vasodilation in response to administered insulin

Meal-induced sensitization to the dynamic actions of insulin results from the peripheral actions of a hormone released by the liver (hepatic insulin sensitizing substance or HISS). Absence of meal-induced insulin sensitization results in the pathologies associated with cardiometabolic risk. Using three protocols that have previously demonstrated HISS metabolic action, we tested the hypothesis that HISS accounts for the vasodilation that has been associated with insulin. The dynamic metabolic actions of insulin and HISS were determined using a euglycemic clamp in response to a bolus of 100 mU/kg insulin in pentobarbital-anesthetized Sprague-Dawley rats. Hindlimb blood flow was measured with an ultrasound flow probe on the aorta above the bifurcation of the iliac arteries. Fed rats showed tightly coupled metabolic and vascular responses, which were completed by 35 min after insulin administration. Blocking HISS release, with the use of atropine or hepatic surgical denervation, eliminated the HISS-dependent metabolic and vascular responses to insulin administration. Physiological suppression of HISS release occurs with fasting. In 24-h fasted rats, HISS metabolic and vascular actions were absent, and atropine had no effect on either action. Fed rats with liver denervation did not release HISS, but intraportal venous infusion of acetylcholine, to mimic the permissive parasympathetic nerve signal, restored the ability of insulin to cause HISS release and restored both the metabolic and vascular actions. These studies report vascular actions of HISS for the first time and demonstrate that HISS, not insulin action, results in the peripheral vasodilation generally attributed to insulin.

Adipocytokines in atherothrombosis: focus on platelets and vascular smooth muscle cells

Visceral obesity is a relevant pathological condition closely associated with high risk of atherosclerotic vascular disease including myocardial infarction and stroke. The increased vascular risk is related also to peculiar dysfunction in the endocrine activity of adipose tissue responsible of vascular impairment (including endothelial dysfunction), prothrombotic tendency, and low-grade chronic inflammation. In particular, increased synthesis and release of different cytokines, including interleukins and tumor necrosis factor-α (TNF-α), and adipokines—such as leptin—have been reported as associated with future cardiovascular events. Since vascular cell dysfunction plays a major role in the atherothrombotic complications in central obesity, this paper aims at focusing, in particular, on the relationship between platelets and vascular smooth muscle cells, and the impaired secretory pattern of adipose tissue.