Vascular insulin resistance: a potential link between cardiovascular and metabolic diseases

Molecular chemical structure of fetuin and its effect on atherosclerosis: TyG index and insulin resistance in different sexes

Atherosclerosis is a common cardiovascular disease, the mechanism of which is complex and related to many factors. Changes in the molecular chemical structure of fetoglobulin may play a key role in the development of atherosclerosis. The aim of this study was to reveal how the chemical structure of fetoglobulin affects atherosclerosis and to analyze its association with TyG index and insulin resistance in different sexes. Subjects were patients with confirmed atherosclerosis and were grouped according to carotid color ultrasound and clinical criteria. The chemical structure of fetoglobulin, TyG index, and the role of insulin resistance in atherosclerosis were evaluated by collecting baseline data and conducting corresponding statistical analyses, including multivariate logistic regression analysis. The results showed that the molecular chemical structure of fetoglobulin was significantly different in patients with atherosclerosis. Multivariate logistic regression analysis showed that fetoglobulin level was significantly correlated with the occurrence of carotid atherosclerosis. TyG index and the association between insulin resistance and the incidence of carotid atherosclerosis were also significantly different in different genders.

The relationship between triglyceride-glucose index and serum neurofilament light chain: Findings from NHANES 2013-2014

BACKGROUND

The Triglyceride-Glucose (TyG) index has become a reliable indicator for evaluating the level of insulin resistance, a pivotal factor in both metabolic and neurodegenerative disorders. Serum neurofilament light chain (sNfL) serves as a responsive biomarker for detecting neuroaxonal injury. Despite this, the interplay between the TyG index and sNfL levels has not been sufficiently investigated. The aim of this research is to scrutinize the correlation between TyG index and sNfL levels across a substantial, population-based cohort.

METHODS

Our study involved an examination of the dataset from the 2013-2014 round of the National Health and Nutrition Examination Survey (NHANES), encompassing a total of 2029 enrolled subjects. The TyG index was calculated using fasting triglycerides and glucose levels. Multivariable linear regression models were conducted to evaluate the relationship between TyG index and sNfL levels, adjusting for potential confounders such as age, sex, race, BMI, hypertension, stroke, congestive heart failure, alcohol consumption and NHHR (Non-High-Density Lipoprotein Cholesterol to High-Density Lipoprotein Cholesterol Ratio). Nonlinear associations were investigated using regression models based on restricted cubic splines (RCS).

RESULTS

Both the unadjusted and adjusted regression analyses revealed a substantial positive correlation between the TyG index and ln-sNfL levels. After accounting for all covariates, each unit increase in the TyG index was associated with a 0.15 (95% CI: 0.02-0.27, p =  0.04) increase in ln-sNfL levels. RCS analysis revealed a nonlinear relationship, with a threshold around a TyG index value of 9.63, beyond which ln-sNfL levels increased more rapidly. The association was consistent across subgroups.

CONCLUSION

Our study links higher TyG index with increased sNfL levels, indicating insulin resistance's role in neuroaxonal injury. The nonlinear relationship implies a heightened risk of neurodegeneration beyond a certain insulin resistance threshold. This underscores the need for early metabolic interventions to prevent neurodegenerative processes.

Modelling the effects of elevated methylglyoxal levels on vascular and metabolic complications

Methylglyoxal (MGO), a glycolysis by-product and precursor to advanced glycation endproducts (AGEs), is associated with glucose intolerance, type 2 diabetes, and vascular dysfunction. This study examined the long-term effects of elevated MGO on blood pressure, insulin sensitivity, and vascular function in healthy mice. Male C57Bl/6J mice were assigned to control (n = 16) or MGO-treated groups (50 mM in drinking water for 13 weeks, n = 16). Measurements included body weight, fasting plasma glucose, water consumption, blood pressure, and analysis of plasma/tissue for MGO, AGEs, glyoxalase activity, and inflammation markers. Endothelial function was assessed using wire myography, and the response of human placental arteries to MGO-modified insulin was evaluated. MGO treatment significantly increased plasma MGO (123.3%, p < 0.001), AGEs MG-H1 (208.6%, p < 0.001) and CEL (64.3%, p < 0.001), and AGEs in the heart, kidney, and liver, along with body weight (+ 6.4%, p = 0.032) and blood pressure (systolic + 5.0%, p = 0.046; diastolic + 6.5%, p = 0.043). Glucose sensitivity and endothelial function remained unaffected. CRP levels rose, and MGO-modified insulin enhanced vascular contraction. In conclusion, chronic MGO exposure increased plasma MGO to diabetic-like levels, raised body weight and blood pressure, and did not alter glucose sensitivity or endothelial function. Modification of insulin by MGO may contribute to MGO-related changes in blood pressure.

Association of the triglyceride glucose index with myocardial ischemia in patients with minimal to moderate coronary artery disease

The triglyceride glucose (TyG) index has been suggested as a reliable substitute to indicate insulin resistance. Several studies have identified the association between the TyG index and cardiovascular disease. However, the association between the TyG index and the incidence of myocardial ischemia in patients with minimal to moderate coronary artery disease (CAD) has not been clearly assessed. We aimed to investigate the association between the TyG index and the incidence of myocardial ischemia in patients with minimal to moderate CAD. A total of 1,697 patients who underwent coronary computed tomography angiography (CTA) examinations and had minimal to moderate CAD were retrospectively included in the study. The TyG index and computed tomography-derived fractional flow reserve (CT-FFR) were used to assess insulin resistance (IR) and myocardial ischemia, respectively. Myocardial ischemia was defined as a CT-FFR value ≤ 0.80. Logistic regression models were used to explore the associations between the TyG index and myocardial ischemia. The incidence of myocardial ischemia was higher in the highest TyG index tertile (T3) group than in the lowest TyG index tertile (T1) group. After adjusting for other variables, the T3 group remained associated with a higher risk of myocardial ischemia than the T1 group did (OR, 1.43; 95% CI, 1.01-2.04; p = 0.047). A 1- standard deviation (SD) increase in the TyG index was correlated with a 19-24% elevated risk of myocardial ischemia when regarding the TyG index was considered as a continuous variable. Subgroup analysis revealed similar effects. A TyG index is associated with a higher risk of myocardial ischemia detected by CT-FFR in patients with minimal to moderate CAD.

Vascular Impairment, Muscle Atrophy, and Cognitive Decline: Critical Age-Related Conditions

The triad of vascular impairment, muscle atrophy, and cognitive decline represents critical age-related conditions that significantly impact health. Vascular impairment disrupts blood flow, precipitating the muscle mass reduction seen in sarcopenia and the decline in neuronal function characteristic of neurodegeneration. Our limited understanding of the intricate relationships within this triad hinders accurate diagnosis and effective treatment strategies. This review analyzes the interrelated mechanisms that contribute to these conditions, with a specific focus on oxidative stress, chronic inflammation, and impaired nutrient delivery. The aim is to understand the common pathways involved and to suggest comprehensive therapeutic approaches. Vascular dysfunctions hinder the circulation of blood and the transportation of nutrients, resulting in sarcopenia characterized by muscle atrophy and weakness. Vascular dysfunction and sarcopenia have a negative impact on physical function and quality of life. Neurodegenerative diseases exhibit comparable pathophysiological mechanisms that affect cognitive and motor functions. Preventive and therapeutic approaches encompass lifestyle adjustments, addressing oxidative stress, inflammation, and integrated therapies that focus on improving vascular and muscular well-being. Better understanding of these links can refine therapeutic strategies and yield better patient outcomes. This study emphasizes the complex interplay between vascular dysfunction, muscle degeneration, and cognitive decline, highlighting the necessity for multidisciplinary treatment approaches. Advances in this domain promise improved diagnostic accuracy, more effective therapeutic options, and enhanced preventive measures, all contributing to a higher quality of life for the elderly population.

Prognostic value of the triglyceride-glucose index for adverse cardiovascular outcomes in young adult hypertension

BACKGROUND

The triglyceride-glucose (TyG) index is a reliable marker of insulin resistance that is involved in the progression of hypertension. This study aimed to evaluate the association of the TyG index with the risk for major cardiovascular events (MACE) in young adult hypertension.

METHODS

A total of 2,651 hypertensive patients aged 18-40 years were consecutively enrolled in this study. The TyG index was calculated as Ln [triglycerides × fasting plasma glucose/2]. The cutoff value for an elevated TyG index was determined to be 8.43 by receiver-operating characteristic curve analysis. The primary endpoint was MACE, which was a composite of all-cause death, non-fatal myocardial infarction, coronary revascularization, non-fatal stroke, and end-stage renal dysfunction. The secondary endpoints were individual MACE components.

RESULTS

During the median follow-up time of 2.6 years, an elevated TyG index was associated with markedly increased risk of MACE (adjusted hazard ratio [HR] 3.440, P < 0.001) in young hypertensive adults. In subgroup analysis, the elevated TyG index predicted an even higher risk of MACE in women than men (adjusted HR 6.329 in women vs. adjusted HR 2.762 in men, P for interaction, 0.001); and in patients with grade 2 (adjusted HR 3.385) or grade 3 (adjusted HR 4.168) of hypertension than those with grade 1 (P for interaction, 0.024). Moreover, adding the elevated TyG index into a recalibrated Systematic COronary Risk Evaluation 2 model improved its ability to predict MACE.

CONCLUSIONS

An elevated TyG index is associated with a higher risk of MACE in young adult hypertension, particularly in women and those with advanced hypertension. Regular evaluation of the TyG index facilitates the identification of high-risk patients.

Predictive value of the triglyceride-glucose index for short- and long-term all-cause mortality in patients with critical coronary artery disease: a cohort study from the MIMIC-IV database

BACKGROUND

Triglyceride-glucose (TyG) index is linked to a poor prognosis for cardiovascular condition and is a valid indicator of insulin resistance. This study evaluated the potential predicting usefulness of the TyG index for all-cause mortality, both short- and long-term, for those concerning critical coronary artery disease (CAD).

METHODS

In this study, information from 5452 critically-ill individuals with CAD in intensive care units were gathered from the Medical Information Marketplace in Intensive Care (MIMIC-IV) database. Depending on the TyG index degree, the patients were categorized into three categories. Clinical outcomes included short-term (30-day) and long-term (365-day) all-cause mortality. The corresponding relationships involving the TyG index and clinical outcomes were examined by deploying restricted cubic spline (RCS) regression analysis and Cox proportional risk regression.

RESULTS

An increased TyG index was associated with increased 30-day (Tertile 1: 6.1%, Tertile 2: 7.3%, Tertile 3: 9.2%, P = 0.001) and 365-day (Tertile 1: 15.2%, Tertile 2: 17.0%, Tertile 3: 19.6%, P = 0.002) death rates across all causes. Cox regression with multiple variables indicates that higher TyG indices were linked to higher all-caused mortality hazard ratios throughout the short and long terms, with a larger predictive value for the former. RCS regression analyses suggested that the risk of death was notably and linearly that is associated with TyG index.

CONCLUSIONS

The TyG index is a reliable predictor of all-cause mortality at different stages in critically ill CAD patients, with a higher predictive ability for short-term mortality. Early intervention in patients with elevated TyG index may improve their survival outcomes. Future research should delve into understanding its pathophysiological mechanisms and develop intervention strategies based on the TyG index, providing new insights and strategies to enhance the outlook for critically ill CAD patients.

Association between surrogate marker of insulin resistance and bone mineral density in US adults without diabetes

This study examines the relationship between TyG-BMI, an indicator of insulin resistance, and bone mineral density in US adults without diabetes, revealing a positive association. The findings suggest that higher TyG-BMI levels may be linked to a lower risk of osteoporosis, providing a basis for future research in this area.

OBJECTIVE

Patients with osteoporosis are often diagnosed with type 2 diabetes or prediabetes. Insulin resistance is a prediabetic state, and triglyceride glucose-body mass index (TyG-BMI) has been recognized as a potential predictor of it, valuable in assessing prediabetes, atherosclerosis, and other diseases. However, the validity of TyG-BMI in osteoporosis studies remains inadequate.

PURPOSE

The purpose of this study was to evaluate the relationship between TyG-BMI and BMD as well as the effect of TyG-BMI on the odds of developing osteoporosis in US adults without diabetes.

METHODS

National Health and Nutrition Examination Survey data were obtained. The relationship between TyG-BMI and BMD was evaluated via multivariate linear regression models. Smoothed curve fitting and threshold effect analysis explored potential non-linear relationships, and age, gender, and race subgroup analyses were performed. In addition, multivariate logistic regression models were employed to analyze its potential role in the development of osteoporosis.

RESULTS

In a study of 6501 participants, we observed a significant positive correlation between the TyG-BMI index and BMD, even after adjusting for covariates and categorizing TyG-BMI. The study identified specific TyG-BMI folding points-112.476 for the total femur BMD, 100.66 for the femoral neck BMD, 107.291 for the intertrochanter BMD, and 116.58 for the trochanter BMD-indicating shifts in the relationship's strength at these thresholds. While the association's strength slightly decreased after the folding points, it remained significant. Subgroup analyses further confirmed the positive TyG-BMI and BMD correlation. Multivariate linear regression analyses indicated a lower osteoporosis risk in participants with higher TyG-BMI levels, particularly in menopausal women over 40 and men over 60.

CONCLUSION

This study suggests a positive correlation between BMD and TyG-BMI in US adults without diabetes. Individuals with higher levels of TyG-BMI may have a lower risk of osteoporosis.

Triglyceride glucose index is associated with functional coronary artery stenosis in hypertensive patients

Background

The triglyceride glucose (TyG) index is an effective method for determining insulin resistance (IR). Limited research has explored the connection between the TyG index and functionally significant stenosis in hypertensive patients. Furthermore, the connections between the TyG index, fat attenuation index (FAI) and atherosclerotic plaque characteristics are also worth exploring.

Methods

The study screened 1622 hypertensive participants without coronary artery disease history who underwent coronary computed tomography angiography. The TyG index was calculated as ln (fasting glucose [mg/dL] * fasting TG [mg/dL]/2). Adverse plaque characteristics (HRPCs), high-risk plaques (HRPs), FAI, and CT-derived fractional flow reserve (FFRCT) were analyzed and measured for all patients. Functionally significant stenosis causing ischemia is defined as FFRCT ≤ 0.80. Two patient groups were created based on the FFRCT: the FFRCT < 0.80 group and the FFRCT > 0.80 group. In hypertensive patients, the association between the TyG index and FFRCT was examined applying a logistic regression model.

Results

The TyG index was higher for people with FFRCT ≤ 0.80 contrast to those with FFRCT > 0.80. After controlling for additional confounding factors, the logistic regression model revealed a clear connection between the TyG index and FFRCT ≤ 0.80 (OR = 1.718, 95% CI 1.097-2.690, p = 0.018). The restricted cubic spline analysis displayed a nonlinear connection between the TyG index and FFRCT ≤ 0.80 (p for nonlinear = 0.001). The TyG index increased the fraction of individuals with HRPs and HRPCs, FAI raised, and FFRCT decreased (p < 0.05). The multivariate linear regression analysis illustrated a powerfulcorrelation between high TyG index levels and FAI, FFRCT, positive remodeling (PR), and low-attenuation plaque (LAPs) (standardized regression coefficients: 0.029 [p = 0.007], -0.051 [p < 0.001], 0.029 [p = 0.027], and 0.026 [p = 0.046], separately).

Conclusion

In hypertensive patients, the TyG index showed an excellent association with a risk of FFRCT ≤ 0.80. Additionally, the TyG index was also linked to FAI, FFRCT, PR, and LAPs.

Association of the metabolic score for insulin resistance with cardiovascular diseases, cardiovascular and all-cause mortality in Chinese hypertensive population

Importance

Little is known about the relationship between the metabolic score for insulin resistance (METS-IR) and the prognosis of hypertensive patients in China.

Objective

To investigate the association between the novel non-insulin-based METS-IR index and the cardiovascular composite endpoints and all-cause mortality in Chinese hypertensive participants.

Design setting and participants

This cohort study used data from the China H-Type Hypertension Project, a long-term prospective cohort consisting of 14234 hypertensive patients in southern China, with a baseline from March to August 2018. The median follow-up period for participants was 3.94 years, as of 2022. The data analysis period is from July 2023 to September 2023.

Exposures

METS-IR index of participants in the Chinese H-type hypertension project. The calculation formula for METS-IR is (Ln (2 × FPG) +TG) × BMI/Ln (HDL-C).

Main outcomes and measures

Cardiovascular events and cardiovascular, all-cause mortality were identified by linking the cohort database with the health care system through October, 2023.

Results

A total of 14220 participants were included in this study. The prevalence rates of cardiovascular disease (CVD), cardiovascular death, and all-cause death were 2.59% (369/14220), 2.79% (397/14220), and 5.66% (805/14220), respectively. After adjusting for confounding factors in the multivariate logistic regression analysis models, the METS-IR index was significantly positively correlated with CVD, and cardiovascular, all-cause mortality, whether as a categorical or continuous variable. Layered analysis showed that the METS-IR index of hypertensive participants in different subgroups was positively correlated with the endpoint event.

Conclusions and relevance

This large, prospective cohort study demonstrated that the METS-IR index, a new IR evaluation index, were independently associated with a higher risk of the cardiovascular composite endpoint and all-cause mortality among Chinese hypertensive population. Importantly, our finding provides an independent indicator for evaluating the prognosis of hypertensive patients.

Gut Microbiota and Insulin Resistance: Understanding the Mechanism of Better Treatment of Type 2 Diabetes Mellitus

Gut microbiota refers to the population of trillions of microorganisms present in the human intestine. The gut microbiota in the gastrointestinal system is important for an individual's good health and well-being. The possibility of an intrauterine colonization of the placenta further suggests that the fetal environment before birth may also affect early microbiome development. Various factors influence the gut microbiota. Dysbiosis of microbiota may be associated with various diseases. Insulin regulates blood glucose levels, and disruption of the insulin signaling pathway results in insulin resistance. Insulin resistance or hyperinsulinemia is a pathological state in which the insulin-responsive cells have a diminished response to the hormone compared to normal physiological responses, resulting in reduced glucose uptake by the tissue cells. Insulin resistance is an important cause of type 2 diabetes mellitus. While there are various factors responsible for the etiology of insulin resistance, dysbiosis of gut microbiota may be an important contributing cause for metabolic disturbances. We discuss the mechanisms in skeletal muscles, adipose tissue, liver, and intestine by which insulin resistance can occur due to gut microbiota's metabolites. A better understanding of gut microbiota may help in the effective treatment of type 2 diabetes mellitus and metabolic syndrome.

Metabolic Syndrome: A Narrative Review from the Oxidative Stress to the Management of Related Diseases

Metabolic syndrome (MS) is a growing disorder affecting thousands of people worldwide, especially in industrialised countries, increasing mortality. Oxidative stress, hyperglycaemia, insulin resistance, inflammation, dysbiosis, abdominal obesity, atherogenic dyslipidaemia and hypertension are important factors linked to MS clusters of different pathologies, such as diabesity, cardiovascular diseases and neurological disorders. All biochemical changes observed in MS, such as dysregulation in the glucose and lipid metabolism, immune response, endothelial cell function and intestinal microbiota, promote pathological bridges between metabolic syndrome, diabesity and cardiovascular and neurodegenerative disorders. This review aims to summarise metabolic syndrome's involvement in diabesity and highlight the link between MS and cardiovascular and neurological diseases. A better understanding of MS could promote a novel strategic approach to reduce MS comorbidities.

The Role of Perivascular Adipose Tissue in the Pathogenesis of Endothelial Dysfunction in Cardiovascular Diseases and Type 2 Diabetes Mellitus

Cardiovascular diseases (CVDs) and type 2 diabetes mellitus (T2DM) are two of the four major chronic non-communicable diseases (NCDs) representing the leading cause of death worldwide. Several studies demonstrate that endothelial dysfunction (ED) plays a central role in the pathogenesis of these chronic diseases. Although it is well known that systemic chronic inflammation and oxidative stress are primarily involved in the development of ED, recent studies have shown that perivascular adipose tissue (PVAT) is implicated in its pathogenesis, also contributing to the progression of atherosclerosis and to insulin resistance (IR). In this review, we describe the relationship between PVAT and ED, and we also analyse the role of PVAT in the pathogenesis of CVDs and T2DM, further assessing its potential therapeutic target with the aim of restoring normal ED and reducing global cardiovascular risk.

Psyllium is a natural nonfermented gel-forming fiber that is effective for weight loss: A comprehensive review and meta-analysis

BACKGROUND

Psyllium is a natural, predominantly soluble fiber that forms a viscous gel when hydrated and is not digested or fermented. In the small intestine, psyllium gel increases chyme viscosity, slowing the degradation and absorption of nutrients. Psyllium has a significant effect in patients with metabolic syndrome and type-2 diabetes on glycemic control, while lowering serum cholesterol in hypercholesterolemic patients. Some randomized controlled studies have shown that psyllium also facilitates weight loss in overweight and obese participants.

OBJECTIVES

A comprehensive review and meta-analysis assessing psyllium's impact on body weight, body mass index (BMI), and waist circumference in overweight and obese participants.

DATA SOURCES

A comprehensive search was performed (Medline, Scopus, Cochrane Database) through March 21, 2022, using search terms to identify randomized, controlled, clinical studies designed to assess weight loss in overweight and obese participants over at least 2 months. Data were analyzed using the inverse variance method with random effects models.

CONCLUSIONS

Six studies meeting inclusion criteria were identified (total n = 354). The meta-analysis showed that psyllium, dosed just before meals (mean dose 10.8 g/day, mean duration 4.8 months), was effective for decreasing body weight (MD = -2.1 kg [95% confidence interval [CI]: -2.6 to -1.6]; p < .001), BMI (MD = -0.8 kg/m2 [95% CI: -1.0 to -0.6]; p < .001) and waist circumference (MD = -2.2 cm [95% CI: -2.9 to -1.4]; p < .001) in overweight and obese populations.

IMPLICATIONS FOR PRACTICE

Gel-forming nonfermented psyllium fiber, dosed just before meals, is effective in facilitating weight loss in overweight and obese participants.

The relationship of insulin resistance and diabetes to tau PET SUVR in middle-aged to older adults

BACKGROUND

Insulin resistance (IR) and type 2 diabetes have been found to increase the risk for Alzheimer's clinical syndrome in epidemiologic studies but have not been associated with tau tangles in neuropathological research and have been inconsistently associated with cerebrospinal fluid P-tau181. IR and type 2 diabetes are well-recognized vascular risk factors. Some studies suggest that cardiovascular risk may act synergistically with cortical amyloid to increase tau measured using tau PET. Utilizing data from largely nondemented middle-aged and older adult cohorts enriched for AD risk, we investigated the association of IR and diabetes to tau PET and whether amyloid moderated those relationships.

METHODS

Participants were enrolled in either the Wisconsin Registry for Alzheimer's Prevention (WRAP) or Wisconsin Alzheimer's Disease Research Center (WI-ADRC) Clinical Core. Two partially overlapping samples were studied: a sample characterized using HOMA-IR (n=280 WRAP participants) and a sample characterized on diabetic status (n=285 WRAP and n=109 WI-ADRC). IR was measured using the homeostasis model assessment of insulin resistance (HOMA-IR). Tau PET employing the radioligand 18F-MK-6240 was used to detect AD-specific aggregated tau. Linear regression tested the relationship of IR and diabetic status to tau PET standardized uptake value ratio (SUVR) within the entorhinal cortex and whether relationships were moderated by amyloid assessed by amyloid PET distribution volume ratio (DVR) and amyloid PET positivity status.

RESULTS

Neither HOMA-IR nor diabetic status was significantly associated with tau PET SUVR. The relationship between IR and tau PET SUVR was not moderated by amyloid PET DVR or positivity status. The association between diabetic status and tau PET SUVR was not significantly moderated by amyloid PET DVR but was significantly moderated by amyloid PET positivity status. Among the amyloid PET-positive participants, the estimated marginal tau PET SUVR mean was higher in the diabetic (n=6) relative to the nondiabetic group (n=88).

CONCLUSION

Findings indicate that IR may not be related to tau in generally healthy middle-aged and older adults who are in the early stages of the AD clinicopathologic continuum but suggest the need for additional research to investigate whether a synergistic relationship between type 2 diabetes and amyloid is associated with increased tau levels.

New insights into mechanisms of endothelial insulin resistance in type 2 diabetes

Insulin resistance in the vasculature is a hallmark of type 2 diabetes (T2D), and blunting of insulin-induced vasodilation is its primary consequence. Individuals with T2D exhibit a marked impairment in insulin-induced dilation in resistance arteries across vascular beds. Importantly, reduced insulin-stimulated vasodilation and blood flow to skeletal muscle limits glucose uptake and contributes to impaired glucose control in T2D. The study of mechanisms responsible for the suppressed vasodilatory effects of insulin has been a growing topic of interest for not only its association with glucose control and extension to T2D but also its relationship with cardiovascular disease development and progression. In this mini-review, we integrate findings from recent studies by our group with the existing literature focused on the mechanisms underlying endothelial insulin resistance in T2D.

Progress in the Preclinical and Clinical Study of Resveratrol for Vascular Metabolic Disease

Vascular metabolic dysfunction presents in various diseases, such as atherosclerosis, hypertension, and diabetes mellitus. Due to the high prevalence of these diseases, it is important to explore treatment strategies to protect vascular function. Resveratrol (RSV), a natural polyphenolic phytochemical, is regarded as an agent to regulate metabolic pathways. Many studies have proven that RSV has beneficial effects on improving metabolism in endothelial cells (ECs) and vascular smooth muscle cells (VSMCs), which provide new directions to treat vascular metabolic diseases. Herein, we overviewed that RSV could regulate cell metabolism activity by inhibiting glucose uptake, suppressing glycolysis, preventing cells from fatty acid-related damages, reducing lipogenesis, increasing fatty acid oxidation, enhancing lipolysis, elevating uptake and synthesis of glutamine, and increasing NO release. Furthermore, in clinical trials, although the results from different studies remain controversial, we proposed that RSV had better therapeutic effects at high concentrations and for patients with metabolic disorders.

ADAM17 cleaves the insulin receptor ectodomain on endothelial cells and causes vascular insulin resistance

Inflammation and vascular insulin resistance are hallmarks of type 2 diabetes (T2D). However, several potential mechanisms causing abnormal endothelial insulin signaling in T2D need further investigation. Evidence indicates that the activity of ADAM17 (a disintegrin and metalloproteinase-17) and the presence of insulin receptor (IR) in plasma are increased in subjects with T2D. Accordingly, we hypothesized that in T2D, increased ADAM17 activity sheds the IR ectodomain from endothelial cells and impairs insulin-induced vasodilation. We used small visceral arteries isolated from a cross-sectional study of subjects with and without T2D undergoing bariatric surgery, human cultured endothelial cells, and recombinant proteins to test our hypothesis. Here, we demonstrate that arteries from subjects with T2D had increased ADAM17 expression, reduced presence of tissue inhibitor of metalloproteinase-3 (TIMP3), decreased extracellular IRα, and impaired insulin-induced vasodilation versus those from subjects without T2D. In vitro, active ADAM17 cleaved the ectodomain of the IRβ subunit. Endothelial cells with ADAM17 overexpression or exposed to the protein kinase-C activator, PMA, had increased ADAM17 activity, decreased IRα presence on the cell surface, and increased IR shedding. Moreover, pharmacological inhibition of ADAM17 with TAPI-0 rescued PMA-induced IR shedding and insulin-signaling impairments in endothelial cells and insulin-stimulated vasodilation in human arteries. In aggregate, our findings suggest that ADAM17-mediated shedding of IR from the endothelial surface impairs insulin-mediated vasodilation. Thus, we propose that inhibition of ADAM17 sheddase activity should be considered a strategy to restore vascular insulin sensitivity in T2D.NEW & NOTEWORTHY To our knowledge, this is the first study to investigate the involvement of ADAM17 in causing impaired insulin-induced vasodilation in T2D. We provide evidence that ADAM17 activity is increased in the vasculature of patients with T2D and support the notion that ADAM17-mediated shedding of endothelial IRα ectodomains is a novel mechanism causing vascular insulin resistance. Our results highlight that targeting ADAM17 activity may be a potential therapeutic strategy to correct vascular insulin resistance in T2D.

Biological Potential of Polyphenols in the Context of Metabolic Syndrome: An Analysis of Studies on Animal Models

Metabolic syndrome (MetS) is a disease that has a complex etiology. It is defined as the co-occurrence of several pathophysiological disorders, including obesity, hyperglycemia, hypertension, and dyslipidemia. MetS is currently a severe problem in the public health care system. As its prevalence increases every year, it is now considered a global problem among adults and young populations. The treatment of choice comprises lifestyle changes based mainly on diet and physical activity. Therefore, researchers have been attempting to discover new substances that could help reduce or even reverse the symptoms when added to food. These attempts have resulted in numerous studies. Many of them have investigated the bioactive potential of polyphenols as a "possible remedy", stemming from their antioxidative and anti-inflammatory effects and properties normalizing carbohydrate and lipid metabolism. Polyphenols may be supportive in preventing or delaying the onset of MetS or its complications. Additionally, the consumption of food rich in polyphenols should be considered as a supplement for antidiabetic drugs. To ensure the relevance of the studies on polyphenols' properties, mechanisms of action, and potential human health benefits, researchers have used laboratory animals displaying pathophysiological changes specific to MetS. Polyphenols or their plant extracts were chosen according to the most advantageous mitigation of pathological changes in animal models best reflecting the components of MetS. The present paper comprises an overview of animal models of MetS, and promising polyphenolic compounds whose bioactive potential, effect on metabolic pathways, and supplementation-related benefits were analyzed based on in vivo animal models.

Association Between Hyperhomocysteinemia Combined with Metabolic Syndrome and Higher Prevalence of Stroke in Chinese Adults Who Have Elevated Blood Pressure

Background

Hyperhomocysteinemia (HHcy) and metabolic syndrome (MS) are established cardiovascular risk factors of stroke and are frequently associated with hypertension. However, studies on the association between HHcy combined with MS and stroke risk in hypertensive patients were absent.

Material/Methods

In 14 059 selected participants with elevated blood pressure, we assessed the prevalence of the MS and stroke. We defined HHcy as plasma total homocysteine >15 μmol/L. MS was defined according to the Chinese Diabetes Society (CDS) criterion. Multivariable analysis was used to examine the association of HHcy or (and) MS with stroke risk in different models.

Results

The prevalence rates of HHcy and MS were 49.96% and 42.21%, respectively. Patients with stroke had higher plasma total homocysteine levels and a higher prevalence of MS (P<0.001). Multivariable analyses indicated that HHcy and MS are independently associated with higher prevalence of stroke (adjusted-odds ratio (OR): 1.36, 95% CI 1.17 to 1.58, P<0.001; adjusted-OR: 1.68, 95% CI 1.44 to 1.96, P<0.001, respectively). Those with combined HHcy and MS had higher odds of stroke than those with isolated HHcy or MS (adjusted-OR: 1.78, 95% CI 1.47 to 2.15, P<0.001; adjusted-OR: 1.39, 95% CI 1.13 to 1.70, P=0.002, respectively).

Conclusions

HHcy combined with MS was associated with higher prevalence of stroke in Chinese adults with elevated blood pressure.

Diabetes and COVID-19: Role of insulin resistance as a risk factor for COVID-19 severity

Patients with diabetes are more susceptible to coronavirus disease 2019 (COVID-19), and as a consequence, develop more severe form of disease. This is partly due to a systemic inflammatory state and pro thrombotic milieu seen in metabolic syndrome. In this review, we attempt to explore the pathogenetic links between insulin resistance and COVID-19 disease severity. Insulin resistance is an underlying condition for metabolic syndromes, including type 2 diabetes, which impairs insulin signaling pathways affecting metabolic and cardiovascular homeostasis. A high concentration of circulating insulin shifts the balance to mitogen activated protein kinase (MAPK)-dependent signaling and causes endothelial cell damage. The phosphatidylinositol 3 kinase and MAPK dependent signaling pathways maintain a balance between nitric oxide-dependent vasodilator and endothelin-1 dependent vasoconstriction actions of insulin. Vascular smooth muscle cell dysfunction is responsible for inflammation and blood coagulation leading to microvascular and macrovascular complications in diabetes. Hyperactivity in renin-angiotensin system is implicated in development of islet oxidative stress and subsequent β-cell dysfunction, as it alters the islet blood flow. These deleterious effects of insulin resistance involving altered blood pressure, vascular dysfunction, and inflammation could be associated with increased severity in COVID-19 patients. We conclude that clinical and/or biochemical markers of insulin resistance should be included as prognostic markers in assessment of acute COVID-19 disease.

Hyperuricemia-induced endothelial insulin resistance: the nitric oxide connection

Hyperuricemia, defined as elevated serum concentrations of uric acid (UA) above 416 µmol L^-1, is related to the development of cardiometabolic disorders, probably via induction of endothelial dysfunction. Hyperuricemia causes endothelial dysfunction via induction of cell apoptosis, oxidative stress, and inflammation; however, it's interfering with insulin signaling and decreased endothelial nitric oxide (NO) availability, resulting in the development of endothelial insulin resistance, which seems to be a major underlying mechanism for hyperuricemia-induced endothelial dysfunction. Here, we elaborate on how hyperuricemia induces endothelial insulin resistance through the disruption of insulin-stimulated endothelial NO synthesis. High UA concentrations decrease insulin-induced NO synthesis within the endothelial cells by interfering with insulin signaling at either the receptor or post-receptor levels (i.e., proximal and distal steps). At the proximal post-receptor level, UA impairs the function of the insulin receptor substrate (IRS) and phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt) in the insulin signaling pathway. At the distal level, high UA concentrations impair endothelial NO synthase (eNOS)-NO system by decreasing eNOS expression and activity as well as by direct inactivation of NO. Clinically, UA-induced endothelial insulin resistance is translated into impaired endothelial function, impaired NO-dependent vasodilation, and the development of systemic insulin resistance. UA-lowering drugs may improve endothelial function in subjects with hyperuricemia.

Current Status of Endoplasmic Reticulum Stress in Type II Diabetes

The endoplasmic reticulum (ER) plays a multifunctional role in lipid biosynthesis, calcium storage, protein folding, and processing. Thus, maintaining ER homeostasis is essential for cellular functions. Several pathophysiological conditions and pharmacological agents are known to disrupt ER homeostasis, thereby, causing ER stress. The cells react to ER stress by initiating an adaptive signaling process called the unfolded protein response (UPR). However, the ER initiates death signaling pathways when ER stress persists. ER stress is linked to several diseases, such as cancer, obesity, and diabetes. Thus, its regulation can provide possible therapeutic targets for these. Current evidence suggests that chronic hyperglycemia and hyperlipidemia linked to type II diabetes disrupt ER homeostasis, thereby, resulting in irreversible UPR activation and cell death. Despite progress in understanding the pathophysiology of the UPR and ER stress, to date, the mechanisms of ER stress in relation to type II diabetes remain unclear. This review provides up-to-date information regarding the UPR, ER stress mechanisms, insulin dysfunction, oxidative stress, and the therapeutic potential of targeting specific ER stress pathways.

Inhibition of Angiotensin-I Converting Enzyme by Ginsenosides: Structure-Activity Relationships and Inhibitory Mechanism

Ginseng (Panax ginseng C. A. Meyer) extract has been reported to inhibit the angiotensin converting enzyme (ACE); however, the possible inhibitory action of most of its constituents (ginsenosides) against ACE remains unknown. Thus, in this study, we investigated ginsenoside derivatives' inhibitory effect on ACE. We assessed the activities of 22 ginsenosides, most of which inhibited ACE significantly. Notably, protopanaxatriol, protopanaxadiol, and ginsenoside Rh2 exhibited the most potent ACE inhibitory potential, with IC₅₀ values of 1.57, 2.22, and 5.60 μM, respectively. Further, a kinetic study revealed different modes of inhibition against ACE. Molecular docking studies have confirmed that ginsenosides inhibit ACE via many hydrogen bonds and hydrophobic interactions with catalytic residues and zinc ion of C- and N-domain ACE that block the catalytic activity of ACE. In addition, we found that the active ginsenosides stimulated glucose uptake in insulin-resistant C2C12 skeletal muscle cells in a dose-dependent manner. Moreover, the most active ginsenosides' reactive oxygen species (ROS) and peroxynitrite (ONOO^-) scavenging properties were evaluated, in which IC₅₀ values ranged from 1.44-43.83 to 2.36-39.56 μM in ONOO^- and ROS, respectively. The results derived from these computational and in vitro experiments provide additional scientific support for the anecdotal use of ginseng in traditional medicine to treat cardiovascular diseases such as hypertension.

The effect of psyllium supplementation on blood pressure: a systematic review and meta-analysis of randomized controlled trials

BACKGROUND/AIMS

Global incidence of hypertension is estimated to be, in excess of, one billion people, and given the efficacy of soluble dietary fibers, in particular, Psyllium, to positively impact blood pressure in patients with hypertension, it is of clinical importance that consensus on its supplementation be established. Therefore, the aim of the study was systematically review and meta-analyze the effect of psyllium supplementation on blood pressure of hypertensive patients in randomized controlled trials.

METHODS

We searched six universal databases including; Pubmed/Medline, Ovid, Cochrane Library, Google Scholar, Embase, and Scopus until November 2018. Both combined and stratified analyzes were conducted. A fixed-effects or random- effects model was used to assess the mean effect sizes.

RESULTS

An eventual 11 trials with 592 participants were considered as eligible for inclusion in the present meta-analysis. The meta-analysis revealed a significant reduction of 2.04 mmHg in systolic blood pressure (weighted mean difference, -2.04; 95% confidence interval, -2.82 to -1.63; p < 0.001). Whilst meta-regression highlighted that the hypotensive effect of psyllium was stronger in subjects with higher baseline blood pressure.

CONCLUSION

Given the overarching benefits and lack of reported side effects, particularly for hypertensive patients, health care providers and clinicians should consider the use of psyllium supplementation for the treatment or abatement of hypertension, or hypertensive symptoms.

Regulation of IRS-1, insulin signaling and glucose uptake by miR-143/145 in vascular smooth muscle cells

Regulation of insulin signaling by microRNAs in smooth muscle cells may contribute to diabetic vascular disease. The two smooth muscle enriched miRNAs miR-143 and miR-145 have been reported to target mediators of insulin signaling in non-smooth muscle cells. In this study, we aimed to determine the importance of this regulation in vascular smooth muscle cells, where expression of miR-143/145 is much higher than in other cell types. Smooth muscle cells deficient of the miR-143/145 cluster were used, as well as smooth muscle cells transfected with mimics/inhibitors for either miR-143 or miR-145. We found that deletion of miR-143/145 in smooth muscle results in a dramatic upregulation IRS-1 expression and insulin signaling, and an increased insulin-induced glucose uptake. Furthermore, specific modulation of either miR-145 or miR-143 expression regulated specific targets (IRS-1, ORP8 and the IGF-1 receptor) in the insulin signaling pathway. Consequently, transient inhibition or overexpression of either miR-143 or miR-145 was sufficient to regulate insulin signaling in smooth muscle cells. In conclusion, the results of this study support an important role for both miR-143 and miR-145 in the regulation of insulin signaling and glucose uptake in vascular smooth muscle cells.

Macrophage Depletion Improves Endothelial Insulin Resistance and Protects against Cardiovascular Injury in Salt-Sensitive Hypertension

Vascular endothelial insulin signaling is critical for the maintenance of vascular and metabolic homeostasis. We have previously shown that in hypertensive Dahl rats, impaired vascular insulin action is linked to angiotensin II activation of the NFκB inflammatory pathway. Macrophage polarization (M1) has implicated in hypertensive and metabolic diseases. Here, we investigated the effect of macrophage depletion using liposome-encapsulated clodronate (LEC) on endothelial insulin resistance and cardiovascular remodeling in Dahl salt-sensitive (DS) rats. High salt intake (HS) for 5 weeks increased systolic blood pressure (SBP: 192 ± 5 vs. 144 ± 4 mmHg in NS, p < 0.05), aortic and cardiac hypertrophy, cardiac fibrosis, and impaired acetylcholine- and insulin-induced vasorelaxation, accompanied by impaired insulin activation of endothelial nitric oxide synthases (eNOS)/NO signaling. HS rats had a significant increase in CD68 (a monocyte/macrophage marker) expression in the aorta and the heart. LEC reduced SBP (168 ± 5 mmHg, p < 0.05) and cardiovascular injury and improved acetylcholine- and insulin-mediated vasorelaxation and insulin signaling molecules with a reduction in the macrophage infiltration in the aorta and the heart. HS rats also manifested an increase in the aortic expressions of inflammatory cytokines, including the ratio of phosphorylated inhibitory kappa B (Iκb)/Iκb, tumor necrosis factor α, and phosphorylated c-Jun N-terminal kinase (JNK) and oxidative stress, which were reduced in HS/LEC rats. Our results suggest that in salt-sensitive hypertension, macrophage may importantly contribute to endothelial insulin resistance, vascular inflammation, and injury. These findings support the idea that macrophages may be a new target for immunotherapy of vasculopathy in hypertensive and metabolic disorders.

Surrogate indexes of insulin resistance and risk of metabolic syndrome in non-Hispanic White, non-Hispanic Black and Mexican American

AIM

To compare the strength of associations between surrogate indexes of insulin resistance (sIR) and risk of metabolic syndrome (MetS) in non-Hispanic White (NHW), non-Hispanic Black (NHB) and Mexican American (MA) adults.

METHODS

The 2013-2016 US National Health and Nutrition Examination Survey data (n = 3435) were used for this study. The associations between sIR that includes Triglyceride/HDL cholesterol ratio (TG/HDL-C), triglyceride glucose (TG) index, visceral adiposity index (VAI), lipid accumulation product (LAP), TG-body mass index (TG-BMI), and TG-waist circumference (TG-WC) and risk for MetS were determined using the prevalence odds ratio (OR) from the logistic regression analyses. Pseudo-R-squared tests were used to estimate the proportion of variance in MetS accounted for by each sIR. Akaike Information Criterion and Bayesian Information Criterion from the multinomial logistic regression analysis were used to compare models that included each sIR and its components separately as predictors of MetS. Areas under curves (AUC) from the receiver-operating characteristic (ROC) were used to detect their diagnostic capabilities.

RESULTS

Compared with other sIR, TG-WC (AUC = 0.899; 95% CI: 0.884-0.913 in NHW) and (AUC = 0.893; 95% CI:0.871-0.915 in NHB), and LAP (AUC = 877; 95% CI: 0.861-0.894 in MA) exhibited the highest diagnostic and predictive accuracy for MetS. Compared with other sIR, TG-WC (OR = 22.8; 95% CI:16.6-31.0 in NHW) and (OR = 22.7; 95% CI:13.1-39.3 in NHB), and LAP (OR = 10.6; 95%:6.6-17.0 in MA) were most significantly associated with increased odds of MetS, adjusting for eGFR, age, marital status, CHD, CHF, income, education, physical activity, alcohol use, smoking and use of cholesterol-lowering medication.

CONCLUSIONS

TG-WC in NHW and NHB, and LAP in MA are more powerful than other proxies of IR in predicting MetS. TG-WC and LAP can serve as adjunctive tools for screening for MetS in NHW, NHB, and MA.

The triglycerides and glucose index is associated with elevated blood pressure in apparently healthy children and adolescents

Prevalence of elevated blood pressure in pediatric population has been increasing worldwide. Thus, the aim of this study was to examine whether the triglycerides and glucose (TyG) index is associated with the presence of prehypertension or hypertension in children and adolescents. Apparently healthy children aged 6 to 15 years were enrolled in a population-based cross-sectional study. Participants were allocated into groups with normal blood pressure (NBP), prehypertension, and hypertension. Smoking, alcohol intake, pregnancy, previous diagnosis of diabetes, kidney, hepatic, or endocrine diseases were exclusion criteria. NBP was defined by systolic and/or diastolic blood pressure < 90th percentile, prehypertension by systolic and/or diastolic blood pressure ≥ 90th < 95th percentile, and hypertension by systolic and/or diastolic blood pressure ≥ 95th percentile, according to age, sex, and height percentiles. A total of 3589 children were enrolled, 1748 (49%) girls and 1841 (51%) boys, and allocated into groups with NBP (n = 2874), prehypertension (n = 271), and hypertension (n = 444). The multiple logistic regression analysis stratified by age and adjusted by the Z-score/SDS of body mass index and waist circumference showed that elevated TyG index was significantly associated with prehypertension (OR = 1.48; 95% CI: 1.08-2.05) and hypertension (OR = 1.63; 95% CI: 1.26-2.11).Conclusion: The results of the present study shows that the elevated TyG index is significantly associated with the presence of prehypertension and hypertension in children and adolescents. What is Known: • Prevalence of elevated blood pressure in children and adolescents has been increasing worldwide. • Insulin resistance plays a key role in the pathogenesis of hypertension. What is New: • The elevated TyG index is significantly associated with the presence of prehypertension in children aged 6-9 years and adolescents aged 10-15 years. • The elevated TyG index is significantly associated with the presence of hypertension in children aged 6-9 years and adolescents aged 10-15 years.

The Association Between Six Surrogate Insulin Resistance Indexes and Hypertension: A Population-Based Study

Background: The relationship between insulin resistance and hypertension is well established, but the association of different surrogate insulin resistance indexes with the presence of hypertension is still under debate. The aim of this study was to compare the strength of the association between the presence of hypertension and six indexes: triglyceride/HDL cholesterol ratio (TG/HDL-C), Triglyceride Glucose (TyG) Index, Visceral adiposity index (VAI), Lipid accumulation product (LAP), TyG-Body mass index (TyG-BMI), and TyG-Waist circumference (TyG-WC). Methods: Data from a cross-sectional epidemiological study enrolling a sample representative for the Romanian population aged 18-80 years, excluding those with diabetes or requiring treatment for hypertriglyceridemia, were used to calculate the six indexes. The association with the presence of hypertension was examined with binomial and multinomial logistic regression. Results: In multinomial logistic models, which included age, gender, smoking, drinking, sedentary lifestyle, estimated glomerular filtration rate, urinary sodium, urinary albumin creatinine ratio, and use of medications known to influence insulin resistance as covariates, all individual components and surrogate insulin resistance indexes were independently associated with the presence of hypertension. Values of pseudo R square ranged from 0.342 for the multivariate model including TG/HDL-C to 0.357 for the model including TyG-WC, but with no clear superiority of any of the tested indexes over all others. Models including BMI and WC had a similar ability to predict the presence of hypertension as most of the surrogate indexes and they were slightly superior to TG/HDL-C and TyG. Conclusions: Although TG/HDL-C, VAI, LAP, TyG, TyG-BMI, and TyG-WC were independently associated with the presence of hypertension, no superiority could be demonstrated over the use of BMI and WC as predictors of hypertension in this cross-sectional study.

Pathophysiology of essential hypertension: an update

INTRODUCTION

Hypertension is caused by increased cardiac output and/or increased peripheral resistance. Areas covered: The various mechanisms affecting cardiac output/peripheral resistance involved in the development of essential hypertension are covered. These include genetics; sympathetic nervous system overactivity; renal mechanisms: excess sodium intake and pressure natriuresis; vascular mechanisms: endothelial cell dysfunction and the nitric oxide pathway; hormonal mechanisms: the renin-angiotensin-aldosterone system (RAAS); obesity, obstructive sleep apnea (OSA); insulin resistance and metabolic syndrome; uric acid; vitamin D; gender differences; racial, ethnic, and environmental factors; increased left ventricular ejection force and hypertension and its association with increased basal sympathetic activity - cortical connections. Expert commentary: Maximum association of hypertension is found with sympathetic overactivity which is directly or indirectly involved in different mechanisms of hypertension including RAAS, OSA, obesity, etc.. It is not overt sympathetic activity but disturbed basal sympathetic tone. Basal sympathetic tone arises from hypothalamus; possibly affected by cortical influences. Therefore, hypertension is not merely a disease of circulatory system alone. Its pathogenesis involves alteration in ANS (autonomic nervous system) and likely in cortical-hypothalamic connections. Assessment of ANS and cortical-hypothalamic connections may be required for better understanding of hypertension.

Increased endothelial shear stress improves insulin-stimulated vasodilatation in skeletal muscle

KEY POINTS

It has been postulated that increased blood flow-associated shear stress on endothelial cells is an underlying mechanism by which physical activity enhances insulin-stimulated vasodilatation. This report provides evidence supporting the hypothesis that increased shear stress exerts insulin-sensitizing effects in the vasculature and this evidence is based on experiments in vitro in endothelial cells, ex vivo in isolated arterioles and in vivo in humans. Given the recognition that vascular insulin signalling, and associated enhanced microvascular perfusion, contributes to glycaemic control and maintenance of vascular health, strategies that stimulate an increase in limb blood flow and shear stress have the potential to have profound metabolic and vascular benefits mediated by improvements in endothelial insulin sensitivity.

ABSTRACT

The vasodilator actions of insulin contribute to glucose uptake by skeletal muscle, and previous studies have demonstrated that acute and chronic physical activity improves insulin-stimulated vasodilatation and glucose uptake. Because this effect of exercise primarily manifests in vascular beds highly perfused during exercise, it has been postulated that increased blood flow-associated shear stress on endothelial cells is an underlying mechanism by which physical activity enhances insulin-stimulated vasodilatation. Accordingly, herein we tested the hypothesis that increased shear stress, in the absence of muscle contraction, can acutely render the vascular endothelium more insulin-responsive. To test this hypothesis, complementary experiments were conducted using (1) cultured endothelial cells, (2) isolated and pressurized skeletal muscle arterioles from swine, and (3) humans. In cultured endothelial cells, 1 h of increased shear stress from 3 to 20 dynes cm^-2 caused a significant shift in insulin signalling characterized by greater activation of eNOS relative to MAPK. Similarly, isolated arterioles exposed to 1 h of intraluminal shear stress (20 dynes cm^-2 ) subsequently exhibited greater insulin-induced vasodilatation compared to arterioles kept under no-flow conditions. Finally, we found in humans that increased leg blood flow induced by unilateral limb heating for 1 h subsequently augmented insulin-stimulated popliteal artery blood flow and muscle perfusion. In aggregate, these findings across models (cells, isolated arterioles and humans) support the hypothesis that elevated shear stress causes the vascular endothelium to become more insulin-responsive and thus are consistent with the notion that shear stress may be a principal mechanism by which physical activity enhances insulin-stimulated vasodilatation.

Resistin-Induced Endoplasmic Reticulum Stress Contributes to the Impairment of Insulin Signaling in Endothelium

Background: Endoplasmic reticulum (ER) stress plays an important role in the pathogenesis of obesity, insulin resistance and cardiovascular diseases (CVDs). Impairment of insulin vascular action may represent a mechanism linking insulin resistance and CVDs. The present study tested the hypothesis that adipocyte-derived resistin inhibits insulin-stimulated endothelial NO production through the induction of ER stress.

Methods and Results: Human umbilical vein endothelial cells (HUVC) were incubated with tunicamycin (an inducer of ER stress, 1–20 μg/mL) or resistin (10–100 ng/mL) for 1 h. Either tunicamycin or resistin increased GRP78 (an ER stress marker) expression associated with the impairment of insulin-stimulated Akt/eNOS phosphorylation, which were prevented by TUDCA (an ER stress suppressor). Resistin increased reactive oxygen species (ROS) production, antioxidant treatment inhibited resistin-induced GRP78 expression and impairment of insulin Akt/eNOS signaling, suggesting that ROS may involve resistin-induced ER stress. Resistin also increased JNK phosphorylation, which was prevented by TUDCA. JNK inhibitor SP600125 relieved the resistin inhibitory effects on endothelial insulin Akt/eNOS signaling. In ex vivo experiments, the incubation of aortic rings with resistin impaired insulin- but not acetylcholine-induced vasodilation, which was restored by TUDCA. LNAME (a NOS inhibitor) abolished insulin-induced vasorelaxation in the control or the resistin-treated aortic rings. In addition, resistin increased the mRNA expressions of proinflammatory cytokines tumor nuclear factor (TNF)α and interleukin (IL)-1β, which were also prevented by TUDCA.

Conclusion: Our results support the ideal that ER stress may play an important role for resistin impairment of vascular insulin signaling and insulin action. The mitigation of ER stress may represent a new strategy for prevention and treatment of CVDs in obesity and insulin resistant-related diseases.

High Concentration of Insulin Induces MUC5AC Expression via Phosphoinositide 3 Kinase/AKT and Mitogen-activated Protein Kinase Signaling Pathways in Human Airway Epithelial Cells

Background Insulin is involved in a glucose homeostatic regulation and a cellular metabolism via phosphorylation of phosphoinositide 3 kinase (PI3K) pathway and mitogen-activated protein kinase (MAPK) pathway. Hyperinsulinemia reduces insulin sensitivity and is an obvious potential factor affecting airway inflammation in chronic airway diseases. MUC5AC is a major secreted mucin, which plays a critical role in inflammatory response in the respiratory tract. However, the relationship between insulin and MUC5AC expression has not been studied. Objective This study investigated the effect and the brief signaling pathway of high concentration of insulin (HI) on MUC5AC expression in human airway epithelial cell. Methods In NCI-H292 cells and primary cultures of normal nasal epithelial cells, the effect and signaling pathway of HI on MUC5AC expression were investigated using reverse transcriptase-polymerase chain reaction (RT-PCR), real-time PCR, enzyme immunoassay, and immunoblot analysis with several specific inhibitors and small interfering RNA (siRNA). Results HI significantly increased MUC5AC expression and activated PI3K/AKT, extracellular signal-related kinase 1/2 (ERK1/2) and p38 MAPKs. The specific PI3K and AKT inhibitor as well as knockdown of AKT1 and AKT2 by the respective siRNAs significantly blocked HI-mediated expression of MUC5AC. Meanwhile, the specific ERK1/2 MAPK and p38 MAPK inhibitor as well as knockdown of ERK1, ERK2, and p38 MAPK by the respective siRNAs also attenuated HI-induced expression of MUC5AC. Conclusion The results of this study suggest that HI induces MUC5AC expression via PI3K/AKT and MAPK signaling pathways in human airway epithelial cells.

Metabolic syndrome: an update on diagnostic criteria, pathogenesis, and genetic links

Metabolic syndrome (MetS), today a major global public health problem, is a cluster of clinical, metabolic, and biochemical abnormalities, such as central adiposity, hypertension, insulin resistance, and dyslipidemias. These MetS-related traits significantly increase the risk of type 2 diabetes mellitus, adverse cardiac events, stroke, and hepatic steatosis. The pathogenesis of MetS is multifactorial, with the interplay of environmental, nutritional, and genetic factors. Chronic low-grade inflammation together with visceral adipose tissue, adipocyte dysfunction, and insulin resistance plays a major role in the progression of the syndrome by impairing lipid and glucose homeostasis in insulin-sensitive tissues, such as the liver, muscle, and adipocytes. Adipose-derived inflammatory cytokines and non-esterified fatty acids establish the link between central obesity IR, inflammation, and atherogenesis. Various studies have reported an association between MetS and related traits with single-nucleotide polymorphisms of different susceptibility genes. Modulation of cytokine levels, pro-oxidants, and disturbed energy homeostasis, in relation to the genetic variations, is described in this review of the recent literature, which also provides updated data regarding the epidemiology, diagnostic criteria, and pathogenesis of MetS.

Association between insulin resistance and the development of cardiovascular disease

For many years, cardiovascular disease (CVD) has been the leading cause of death around the world. Often associated with CVD are comorbidities such as obesity, abnormal lipid profiles and insulin resistance. Insulin is a key hormone that functions as a regulator of cellular metabolism in many tissues in the human body. Insulin resistance is defined as a decrease in tissue response to insulin stimulation thus insulin resistance is characterized by defects in uptake and oxidation of glucose, a decrease in glycogen synthesis, and, to a lesser extent, the ability to suppress lipid oxidation. Literature widely suggests that free fatty acids are the predominant substrate used in the adult myocardium for ATP production, however, the cardiac metabolic network is highly flexible and can use other substrates, such as glucose, lactate or amino acids. During insulin resistance, several metabolic alterations induce the development of cardiovascular disease. For instance, insulin resistance can induce an imbalance in glucose metabolism that generates chronic hyperglycemia, which in turn triggers oxidative stress and causes an inflammatory response that leads to cell damage. Insulin resistance can also alter systemic lipid metabolism which then leads to the development of dyslipidemia and the well-known lipid triad: (1) high levels of plasma triglycerides, (2) low levels of high-density lipoprotein, and (3) the appearance of small dense low-density lipoproteins. This triad, along with endothelial dysfunction, which can also be induced by aberrant insulin signaling, contribute to atherosclerotic plaque formation. Regarding the systemic consequences associated with insulin resistance and the metabolic cardiac alterations, it can be concluded that insulin resistance in the myocardium generates damage by at least three different mechanisms: (1) signal transduction alteration, (2) impaired regulation of substrate metabolism, and (3) altered delivery of substrates to the myocardium. The aim of this review is to discuss the mechanisms associated with insulin resistance and the development of CVD. New therapies focused on decreasing insulin resistance may contribute to a decrease in both CVD and atherosclerotic plaque generation.

Dietary Fibre as a Unifying Remedy for the Whole Spectrum of Obesity-Associated Cardiovascular Risk

Obesity is a pandemic carrying the heavy burden of multiple and serious co-morbidities including metabolic syndrome, type 2 diabetes and cardiovascular diseases. The pathophysiological processes leading to the accumulation of body fat slowly evolve to fat accumulation in other body compartments than subcutaneous tissue. This abnormal fat deposition determines insulin resistance which in turn causes blood glucose and lipid metabolism derangement, non-alcoholic fatty liver disease, hypertension, and metabolic syndrome. All these conditions contribute to increase the cardiovascular risk of obese people. Several randomized clinical trials demonstrated that moderate weight loss (5⁻10%) in obese patients improves obesity-related metabolic risk factors and coexisting disorders. Therefore, nutritional strategies able to facilitate weight management, and in the meantime positively influence obesity-associated cardiovascular risk factors, should be implemented. To this aim, a suitable option could be dietary fibres that may also act independently of weight loss. The present narrative review summarizes the current evidence about the effects of dietary fibres on weight management in obese people. Moreover, all of the different cardiovascular risk factors are individually considered and evidence on cardiovascular outcomes is summarized. We also describe the plausible mechanisms by which different dietary fibres could modulate cardio-metabolic risk factors. Overall, despite both epidemiological and intervention studies on weight loss that show statistically significant but negligible clinical effects, dietary fibres seem to have a beneficial impact on main pathophysiological pathways involved in cardiovascular risk (i.e., insulin resistance, renin-angiotensin, and sympathetic nervous systems). Although the evidence is not conclusive, this suggests that fibre would be a suitable option to counteract obesity-related cardio-metabolic diseases also independently of weight loss. However, evidence is not consistent for the different risk factors, with clear beneficial effects shown on blood glucose metabolism and Low Density Lipoprotein (LDL) cholesterol while there is fewer, and less consistent data shown on plasma triglyceride and blood pressure. Ascribing the beneficial effect of some foods (i.e., fruits and vegetables) solely to their fibre content requires more investigation on the pathophysiological role of other dietary components, such as polyphenols.

The effect of viscous soluble fiber on blood pressure: A systematic review and meta-analysis of randomized controlled trials

AIMS

Dietary fiber intake, especially viscous soluble fiber, has been established as a means to reduce cardiometabolic risk factors. Whether this is true for blood pressure remains controversial. A systematic review and meta-analysis of randomized controlled trials (RCTs) was conducted to investigate the effects of viscous soluble fiber supplementation on blood pressure and quantify the effect of individual fibers.

DATA SYNTHESIS

MEDLINE, Embase, and Cochrane databases were searched. We included RCTs of ≥4-weeks in duration assessing viscous fiber supplementation from five types: β-glucan from oats and barley, guar gum, konjac, pectin and psyllium, on systolic blood pressure (SBP) and diastolic blood pressure (DBP). Study data were pooled using the generic inverse variance method with random effects models and expressed as mean differences (MD) with 95% confidence intervals (CIs). Twenty-two (N = 1430) and twenty-one RCTs (N = 1343) were included in the final analysis for SBP and DBP, respectively. Viscous fiber reduced SBP (MD = -1.59 mmHg [95% CI: -2.72,-0.46]) and DBP (MD = -0.39 mmHg [95% CI: -0.76,-0.01]) at a median dose of 8.7 g/day (1.45-30 g/day) over a median follow-up of 7-weeks. Substantial heterogeneity in SBP (I² = 72%, P < 0.01) and DBP (I² = 67%, P < 0.01) analysis occurred. Within the five fiber types, SBP reductions were observed only for supplementation using psyllium fiber (MD = -2.39 mmHg [95% CI: -4.62,-0.17]).

CONCLUSION

Viscous soluble fiber has an overall lowering effect on SBP and DBP. Inclusion of viscous fiber to habitual diets may have additional value in reducing CVD risk via improvement in blood pressure.

PROTOCOL REGISTRATION

ClinicalTrials.gov identifier-NCT02670967.

Study of insulin vascular sensitivity in aortic rings and endothelial cells from aged rats subjected to caloric restriction: Role of perivascular adipose tissue

The prevalence of metabolic syndrome is dramatically increasing among elderly population. Metabolic syndrome in aged individuals is associated with hyperinsulinemia and insulin resistance both in metabolic tissues and in the cardiovascular system, with this fact being associated with the cardiometabolic alterations associated to this condition. Caloric restriction (CR) improves insulin sensitivity and is one of the dietetic strategies most commonly used to enlarge life and to prevent aging induced cardiovascular alterations. The aim of this study was to analyze the possible beneficial effects of CR in aging-induced vascular insulin resistance both in aortic rings and in primary culture of endothelial cells. In addition, the inflammatory profile of perivascular adipose tissue (PVAT) and its possible role in the impairment of vascular insulin sensitivity associated with aging was also assessed. Three experimental groups of male Wistar rats were used: 3 (3m), 24 (24m) fed ad libitum and 24months old rats subjected to 20% CR during their three last months of life (24m-CR). Aorta rings surrounded or not by PVAT were mounted in an organ bath and precontracted with phenylephrine (10^-7.5M). Changes in isometric tension were recorded in response to cumulative insulin concentrations (10^-8-10^-5.5M) in the presence or absence of L-NAME (10^-4M). Aortic rings and primary aortic endothelial cells were incubated in presence/absence of insulin (10^-7M) and the activation of the PI3K/Akt and MAPK pathways as well as nitrite and nitrates concentrations and the mRNA levels of eNOS, insulin receptor, and GLUT-4 were assessed. CR prevented the aging-induced decrease in the vasodilator response to insulin and the aging-induced increase in the vasoconstrictor response to high insulin concentrations. Changes between 24m and 24m-CR aorta rings were abolished in the presence of L-NAME. CR induced-improvement in insulin vascular sensitivity was related with activation of the PI3K/Akt both in aortic rings and in aortic endothelial cells in response to insulin. CR attenuated the overexpression of iNOS, TNF-α and IL-1β in the PVAT of aged rats although aortic rings surrounded by PVAT from 24m rats showed and increased vasorelaxation in response to insulin compared to aortic rings from 3m and 24m-CR rats. In conclusion, a moderate protocol of CR improves insulin vascular sensitivity and prevents the aging induced overexpression of pro-inflammatory cytokines in PVAT.

Impact of nonfasting triglycerides/high-density lipoprotein cholesterol ratio on secondary prevention in patients treated with statins

BACKGROUND

Some studies have demonstrated that low-density lipoprotein cholesterol (LDL-C) lowering therapy is one of the most important strategies to prevent coronary artery disease. Also, serum triglycerides (TG) and high-density lipoprotein cholesterol (HDL-C) are recognized as independent risk factors of cardiovascular diseases. The aim of this study was to investigate whether the nonfasting TG/HDL-C ratio could affect the incidence of cardiovascular events after percutaneous coronary intervention (PCI) even in patients treated with statins.

METHODS AND RESULTS

One thousand one hundred seventy consecutive patients were enrolled, all of whom underwent successful PCI for acute coronary syndrome or stable angina and continued statin treatments after PCI. They were equally divided into three groups on the basis of a nonfasting TG/HDL-C ratio 3 months after PCI. Among these groups, the incidence of major adverse cardiac events (MACE) was measured during a maximum of 5 years after PCI. MACE was defined as cardiac death, nonfatal myocardial infarction, revascularization due to new stenosis or restenosis. Kaplan-Meier analysis demonstrated that patients with higher TG/HDL-C ratio had a significantly higher incidence of MACE than other groups (p<0.001). In addition, Cox proportional hazards regression analysis indicated that the nonfasting TG/HDL-C ratio was significantly correlated with the incidence of MACE.

CONCLUSION

The nonfasting TG/HDL-C ratio was a valuable predictor of cardiovascular events after PCI in patients treated with statins.

Puerarin Improves Vascular Insulin Resistance and Cardiovascular Remodeling in Salt-Sensitive Hypertension

Puerarin is an isoflavonoid isolated from the Chinese herb, Kudzu roots (also known as Gegen), which has been widely used for the treatment of hypertensive diseases and diabetic mellitus in traditional Chinese medicine. Dahl salt-sensitive (DS) rat is a genetic model of salt-sensitive hypertension with cardiovascular injury and vascular insulin resistance. Here, we investigated whether puerarin improved vascular insulin resistance and attenuated cardiac and aortic remodeling in salt-sensitive hypertension. DS rats were given a normal (NS) or high salt diet (HS) for five weeks. An additional group of DS rats was pretreated with puerarin and NS for 10 days, then switched to HS plus puerarin for five weeks. HS for five weeks increased systolic blood pressure (SBP), cardiac hypertrophy and fibrosis, and aortic hypertrophy with increased the expression of phosphor-ERK1/2 in the aorta and heart; puerarin attenuated cardiac and aortic hypertrophy, cardiac fibrosis and phosphor-ERK1/2 with a mild reduction in SBP. Hypertensive rats also manifested impairment of acetylcholine- and insulin-mediated vasorelaxation and insulin-mediated Akt and eNOS phosphorylation associated with the activation of NF[Formula: see text]B/TNF[Formula: see text]/JNK pathway. Puerarin improved acetylcholine- and insulin-mediated vasorelaxation and insulin-stimulated Akt/NO signaling with the inhibition of the NF[Formula: see text]B inflammatory pathway. Our results demonstrated that in salt-sensitive hypertension, puerarin improved vascular insulin action with cardiovascular beneficial effects. Our results found that the underlying mechanisms may involve its inhibition of NF[Formula: see text]B/JNK and ERK1/2 pathway. These results suggest that puerarin could be used as a new antihypertensive agent to expand our armamentarium for the prevention and treatment of end-organ damage in individuals with hypertension and metabolic diseases.

Differential Metabolic Effects of Beta-Blockers: an Updated Systematic Review of Nebivolol

Blood pressure management in hypertensive patients with metabolic abnormalities is challenging, since many of the antihypertensive drugs adversely affect metabolism. Besides effective control of blood pressure in patients with hypertension, third-generation beta-blockers such as nebivolol offer additional benefits for central hemodynamics and neutral or beneficial effects on metabolism. Emerging clinical data suggest that nebivolol also has similar effects on metabolism in obese hypertensive and hypertensive diabetic patients. The present article will provide a systematic analysis of the pathophysiological links among hypertension, insulin resistance, and metabolic syndrome. We will also summarize the available clinical evidence regarding the metabolic effects of beta-blockers in hypertensive patients, with an emphasis on nebivolol. Nebivolol exerts neutral or beneficial effects on insulin sensitivity and lipid metabolism in hypertensive patients, owing to its nitric oxide-mediated vasodilatory and antioxidative properties. Thus, nebivolol could be a favorable therapeutic option for the treatment of hypertension in patients with impaired glucose and lipid metabolism.

Non-alcoholic fatty liver disease, vascular inflammation and insulin resistance are exacerbated by TRAIL deletion in mice

Non-alcoholic fatty liver disease (NAFLD) incorporates steatosis, non-alcoholic steato-hepatitis (NASH) and liver cirrhosis, associating with diabetes and cardiovascular disease (CVD). TNF-related apoptosis-inducing ligand (TRAIL) is protective of CVD. We aimed to determine whether TRAIL protects against insulin resistance, NAFLD and vascular injury. Twelve-week high fat diet (HFD)-fed Trail^−/− mice had increased plasma cholesterol, insulin and glucose compared to wildtype. Insulin tolerance was impaired with TRAIL-deletion, with reduced p-Akt, GLUT4 expression and glucose uptake in skeletal muscle. Hepatic triglyceride content, inflammation and fibrosis were increased with TRAIL-deletion, with elevated expression of genes regulating lipogenesis and gluconeogenesis. Moreover, Trail^−/− mice exhibited reduced aortic vasorelaxation, impaired insulin signaling, and >20-fold increased mRNA expression for IL-1β, IL-6, and TNF-α. In vitro, palmitate treatment of hepatocytes increased lipid accumulation, inflammation and fibrosis, with TRAIL mRNA significantly reduced. TRAIL administration inhibited palmitate-induced hepatocyte lipid uptake. Finally, patients with NASH had significantly reduced plasma TRAIL compared to control, simple steatosis or obese individuals. These findings suggest that TRAIL protects against insulin resistance, NAFLD and vascular inflammation. Increasing TRAIL levels may be an attractive therapeutic strategy, to reduce features of diabetes, as well as liver and vascular injury, so commonly observed in individuals with NAFLD.

Role of habitual physical activity in modulating vascular actions of insulin

NEW FINDINGS

What is the topic of this review? This review highlights the importance of increased vascular insulin sensitivity for maintaining glycaemic control and cardiovascular health. What advances does it highlight? We discuss the role of habitual physical activity in modulating vascular actions of insulin. Type 2 diabetes and cardiovascular disease commonly coexist. Current evidence suggests that impaired insulin signalling in the vasculature may be a common link between metabolic and cardiovascular diseases, including glycaemic dysregulation and atherosclerosis. Herein, we highlight the importance of the actions of insulin on the vasculature for glycaemic control and arterial health. In addition, we summarize and discuss findings from our group and others demonstrating that increased physical activity may be an effective approach to enhancing vascular insulin sensitivity. Furthermore, in light of the existing literature, we formulate the hypothesis that increased shear stress may be a prime mechanism through which habitual physical activity improves insulin signalling in the vasculature. Ultimately, we propose that targeting vascular insulin resistance may represent a viable strategy for improving glycaemic control and reducing cardiovascular risk in patients with type 2 diabetes.

Varying patterns of brachial artery flow-mediated dilatation in women with polycystic ovary syndrome and controls: An application of the group-based trajectory modeling

PURPOSE

To identify changing patterns of absolute change in brachial artery lumen diameter (LD) after reactive hyperemia in women with polycystic ovary syndrome (PCOS) and controls and to quantify the association of PCOS status and participants' factors with these patterns.

METHODS

Brachial flow-mediated dilation was measured in 128 women with PCOS and 148 controls aged 30-60 years. Group-based trajectory modeling was used to investigate absolute change in LD every 30 seconds for 2 minutes after occluding cuff deflation. Multinomial logistic regression was used to identify factors associated with trajectories.

RESULTS

Three patterns emerged, namely nondilators (42.2%), dilators (44.6%), and enhanced dilators (13.0%). The proportion of women with PCOS did not differ across groups. Independently of age and PCOS status, larger baseline LD (odds ratio; 95% confidence interval: 2.51; 1.29, 4.89) and lower insulin levels (0.70; 0.52, 0.93) were associated with nondilators rather than with dilators. Higher total cholesterol was associated with dilators in women with PCOS but with nondilators in controls.

CONCLUSIONS

Trajectory modeling identified distinct patterns of change in LD and factors associated with the endothelial response. This method may be a useful tool to understand the brachial flow-mediated vasodilator response.