Insulin resistance and upper-normal glucose levels in hypertension: a review

Increased glucose concentration modifies TGF-β1 and NFκB signaling pathways in aniridia limbal fibroblasts, in vitro

To determine the impact of increased glucose concentration on gene expression of primary healthy human limbal fibroblasts (LFCs) and congenital aniridia human limbal fibroblasts (AN-LFCs), in vitro. LFCs (n = 8) and AN-LFCs (n = 8) were isolated and cultured in serum containing DMEM, including either normal glucose (17.5 mM) or increased glucose (70 mM) concentration for 48h or 72h, respectively. mRNA and protein expression of transforming growth factor beta 1 (TGF-β1), alpha-smooth muscle actin (ACTA)2A1, SMAD 2/3, hypoxia markers such as nuclear factor kappa B (NFκB), inducible nitric oxide synthase (iNOS), hypoxia-inducible factor 1-alpha (HIF-1ɑ), oxidative stress markers such as nuclear factor erythroid 2-related factor 2 (Nrf2) and Catalase (CAT) were analyzed using qPCR and Western blot. In 70 mM glucose concentration medium for 48 h, TGF-β1 mRNA expression was significantly lower (p = 0.001, p < 0.001), Nrf2 (p = 0.001, p = 0.001) and CAT (p = 0.001, p = 0.001) mRNA expression was significantly higher in LFCs and AN-LFCs, than using 17.5 mM glucose concentration medium. In addition, in 70 mM glucose concentration medium for 48 h, SMAD 2, SMAD 3, NFκB, HIF-1ɑ mRNA expression was significantly lower in AN-LFCs, than in 17.5 mM glucose concentration medium (p = 0.003, p = 0.002, p = 0.008, p = 0.020). At this time-point in 70 mM glucose concentration medium, at protein level, TGF-β1, SMAD2/3 and NFκB were significantly lower in AN-LFCs, than in 17.5 mM glucose concentration medium (p = 0.041, p = 0.002, p = 0.012). In 70 mM glucose concentration medium for 72h, TGF-β1 was significantly higher (p < 0.001, p < 0.001) and Nrf2 (p = 0.001, p = 0.001) and CAT (p < 0.001, p < 0.001) mRNA were significantly lower in LFCs and AN-LFCs, than in 17.5 mM glucose concentration medium. At this time-point, in 70 mM glucose concentration medium, NFκB mRNA was significantly higher (p < 0.001) in LFCs, than in 17.5 mM glucose concentration DMEM medium. In 70 mM glucose concentration medium for 72 h, TGF-β1 and NFκB protein were significantly lower in AN-LFCs, than in 17.5 mM glucose concentration medium (p < 0.001, p < 0.001). Our study confirmed that high glucose concentration has an impact on TGF-β1 and NFκB signaling both in AN-LFCs and LFCs. These findings highlight that prolonged exposure to high glucose levels may contribute to cellular stress and dysfunction in LFCs and AN-LFCs.

Influence of Chronic Forced Immobilization and Consumption of a High-Fat and High-Carbohydrate Diet Containing Cholesterol on Lipid and Cholesterol Metabolism in Male Wistar Rats

We studied the effect of separate and combined influence of chronic forced physical activity reduction and high-fat and high-carbohydrate diet containing cholesterol on some indicators of carbohydrate, lipid, and cholesterol metabolism in growing male Wistar rats. Used combination of factors simulating a sedentary lifestyle and unhealthy diet did not have a synergistic effect on the selected biomarkers. On the contrary, the effect was antagonistic: body weight and appetite decreased and insulin resistance increased. The obtained results indicate certain prospects of hypercholesterolemia model using in preclinical studies of specialized food products to optimize the diet of individuals with disorders of carbohydrate and lipid metabolism.

Retrospective Study of Aging and Sex-Specific Risk Factors of COVID-19 with Hypertension in China

Background

Coronavirus disease 2019 (COVID-19) has been a global threat that pushes healthcare to its limits. Hypertension is one of the most common risk factors for cardiovascular complications in COVID-19 and is strongly associated with disease severity and mortality. To date, clinical mechanisms by which hypertension leads to increased risk in COVID-19 are still unclear. Furthermore, additional factors might increase these risks, such as the consideration of age and sex, which are of interest when in search of personalized treatments for hypertensive COVID-19 patients.

Methods

We conducted a retrospective cohort study of 543 COVID-19 patients in seven provinces of China to examine the epidemiological and clinical characteristics of COVID-19 in this population and to determine risk factors of hypertensive COVID-19 patients. We also used univariable and multivariable logistic regression methods to explore the risk factors associated with hypertensive COVID-19 patients in different age and sex subgroups.

Results

Among the enrolled COVID-19 patients, the median age was 47 years (interquartile range (IQR) 34.0–57.0), and 99 patients (18.23%) were over 60 years old. With regard to comorbidities, 91 patients (16.75%) were diagnosed with hypertension, followed by diabetes, coronary disease, and cerebrovascular disease. Of the hypertensive COVID-19 patients, 51 (56.04%) were male. Multivariable analysis showed that old age, comorbid diabetes or coronary heart disease on admission, increased D-dimer, increased glucose, and decreased lymphocyte count were independent risk factors associated with hypertensive COVID-19 patients. Elevated total bilirubin (odds ratio [OR]: 1.014, 95% confidence interval [CI]: 0.23–1.05; p = 0.043) and triglycerides (OR: 1.173, 95% CI: 0.049–1.617; p = 0.007) were found to be associated with elderly hypertensive COVID-19 patients. In addition, we found that decreased lymphocytes, basophil, high-density lipoprotein, and increased fibrinogen and creatinine were related to a higher risk of disease severity in male patients. The most common abnormal clinical findings pertaining to female hypertensive COVID-19 patients were hemoglobin, total bile acid, total protein, and low-density lipoprotein.

Conclusions

Factors associated with increased risk of hypertensive COVID-19 patients were identified. Results to the different age and sex subgroups in our study will allow for better possible personalized care and also provide new insights into specific risk stratification, disease management, and treatment strategies for COVID-19 patients with hypertension in the future.

INSAF-HAS: a tool to select patients with hypertension for pharmaceutical care

OBJECTIVE

To develop and validate the content of a tool aimed to select patients with hypertension for pharmaceutical care, based on identification of individuals in greater need of attention.

METHODS

The tool was developed and assessed for face and content validity, which was carried out in three stages. Phase I consisted of comprehensive literature review, which prompted the development of the first version of the tool. Phase II consisted of validation by an expert panel. Phase III consisted of a pilot study with hypertensive patients and preparation of the final version of the instrument.

RESULTS

Literature review yielded 30 studies, out of which 13 factors associated with hypertension and cardiovascular disease control and complications were selected. Once the initial version of the tool named INSAF-HAS was obtained, four expert meetings were held, each leading to instrument improvement until a final consensus was reached. In the pilot study, INSAF-HAS was applied to 30 patients with a diagnosis of hypertension for applicability pretest; adjustments were made and the final version of INSAF-HAS obtained.

CONCLUSION

The INSAF-HAS tool developed in this study has face and content validity, and may contribute to the selection of patients with hypertension in greater need of pharmaceutical care services.

Negative regulation of eNOS-NO signaling by over-SUMOylation of PPARγ contributes to insulin resistance and dysfunction of vascular endothelium in rats

SUMOylation of peroxisome proliferator-activated receptor gamma (PPAR γ) plays important regulatory role in its transcriptional activity. Our recent studies in vitro found that over-SUMOylation of PPARγ, like high glucose and high fat (HG/HF), induced endothelial insulin resistance (IR). However, whether such an event occurs in rats remains unclear. Therefore, our study aimed at investigating whether PPARγ over-SUMOylation could mimic high sucrose/fat diet (HFD) to induce endothelial IR and dysfunction and explored its underlying mechanisms. Normal chow-fed rats were intravenously infected with adenoviruses carrying the wild type cDNAs encoding PPARγ, SUMO1 and PIAS1 (protein inhibitor of activated STAT1). HFD-fed rats were regarded as a positive control. Body physical and biochemical parameters, glucose tolerance and vessel function were detected. The expression and SUMOylation levels of PPARγ were measured by western blotting and co-immunoprecipitation. Our results showed that like HFD, PPARγ over-SUMOylation induced endothelial IR and dysfunction via a negative regulation of eNOS-NO pathway. More importantly, we found that PPARγ over-SUMOylation induced endogenous SUMOylation cascade and exacerbated endothelial IR and dysfunction.The findings will deepen the understanding on PPARγ SUMOylation-regulating insulin signaling network and offer a potential target for prevention and cure of diabetic vascular complications.

Higher normal range of fasting plasma glucose still has a higher risk for metabolic syndrome: a combined cross-sectional and longitudinal study in elderly

INTRODUCTION

It is well known that higher fasting plasma glucose (FPG) is associated with metabolic syndrome (MetS). This relationship still exists even the FPG is within the normal range. However, most of these studies did not exclude subjects who were on medications which would affect the results of the studies. At the same time, there is no longitudinal study done to validate this correlation, especially in elderly. In this study, the relationships between normal FPG and MetS were evaluated.

METHOD

We randomly selected 57,517 subjects who were ≥ 60-years old from health screening centre. In the first part of study, subjects were enrolled in the cross-sectional study to find out the optimal cut-off value of FPG with higher chances to have MetS. In the second part of current study, subjects with MetS at baseline were excluded from the same study group, and performed a median 5.3-year longitudinal study.

RESULTS

There were 18,287 subjects enrolled in this study. In the first part of study, the cross-sectional study, optimal cut-off values of FPG were determined by the ROC curve and the sensitivity for these cut-off values were 56.6% in men and 60.9% in women, respectively. The result showed that lower FPG is healthier than the higher (log-rank test, p < 0.001). During the follow-up period, 5039 subjects showed hazard ratios of 2.09 for men and 1.884 for women developing future MetS.

CONCLUSION

Our study is the first longitudinal design in elderly and showed that older subjects with higher FPG proved to have higher risk of Mets even the FPG is still within its normal range.

Prevalence and determinants of hypertension in Estonian adults

Background: Although Eastern Europe, including Estonia, has one of the highest morbidity and mortality rates associated with hypertension, there is little information in the literature concerning the biochemical risk factor profile or its association with hypertension in Estonia. This study examined the cross-sectional gender-stratified association between biochemical risk markers and hypertension in a population-based sample of adults in Estonia. Methods: The study was carried out in Tallinn, Estonia and consisted of 511 men and 600 women with a mean age of 46 years. Physiological measurements were taken and blood samples drawn to measure the following markers: cholesterol, high- and low-density lipoprotein cholesterol, apolipoproteins A-1 and B, lipoprotein(a), triglycerides, glucose, fibrinogen, high-sensitivity C-reactive protein and homocysteine. Results: Overall, 36% of participants had hypertension, with approximately 80% being aware of their condition. A total of 40% of participants reported taking antihypertensive medication. Multivariate binary logistic regression analysis showed that a decrease in high-density lipoprotein cholesterol and increases in age, body mass index, apolipoprotein B, triglyceride and homocysteine levels were associated with an increased probability of hypertension. Conclusions: Elevations in biochemical markers and cardiovascular risk factors are associated with hypertension. Increasing body mass index, triglyceride, apolipoprotein B and homocysteine levels with decreasing high-density lipoprotein cholesterol level should be investigated and monitored in Estonian adults.

Roles of insulin, age, and asymmetric dimethylarginine on nitric oxide synthesis in vivo

We tested the effects of insulin on production of nitrous oxide (NO)-related substances (nitrites and nitrates [NOx]) after (15)N-arginine intravenous infusion and on asymmetric dimethylarginine (ADMA) and symmetric dimethylarginine (SDMA) concentrations in conditions reportedly associated with altered NO availability, i.e., aging, hypertension, hypercholesterolemia, and type 2 diabetes mellitus (T2DM). A total of 26 male subjects (age 23-71 years, BMI 23-33 kg/m(2)), some of whom were affected by mixed pathologic features, were enrolled. NOx fractional synthesis rate (FSR) was lower in elderly (P < 0.015) and T2DM subjects (P < 0.03) than in matched control subjects. Hyperinsulinemia generally increased both NOx FSR and absolute synthesis rate (ASR) and reduced NOx, ADMA, and SDMA concentrations. Insulin sensitivity was impaired only in T2DM. With use of simple linear regression analysis across all subjects, age was inversely correlated with both NOx FSR (R(2) = 0.23, P < 0.015) and ASR (R(2) = 0.21, P < 0.02). NOx FSR inversely correlated with both ADMA and SDMA. With use of multiple regression analysis and various models, NOx FSR remained inversely associated with age and ADMA, whereas ASR was inversely associated with age and diabetes. No association with insulin sensitivity was found. We conclude that whole-body NOx production is decreased in aging and T2DM. Age, ADMA concentration, and T2DM, but not insulin resistance, appear as negative regulators of whole-body NOx production.

Insulin and sex interactions in older adults with mild cognitive impairment

Alzheimer's disease (AD) and other dementias are likely preceded by a protracted preclinical state. Thus, identification of biomarkers that signal potential points of intervention during this prodromal phase (during which patients are largely able to compensate for their cognitive deficits) is of paramount importance. Insulin is a pancreatic hormone with potent central nervous system effects, and insulin dysregulation has been implicated in the pathogenesis of both AD and vascular dementia. The aim of the current study was to determine whether circulating insulin differs as a function of mild cognitive impairment (MCI) diagnosis, and whether this relationship is mediated by sex and apolipoprotein E (APOE) genotype. A sample of 549 nondemented participants aged 65 and over from the Adult Changes in Thought community-based cohort underwent cognitive testing and blood draw to determine fasting levels of plasma insulin. Subjects were categorized as having normal cognitive functioning, amnestic MCI, or nonamnestic MCI. Results showed that the relationship between insulin and diagnostic category is moderated by sex, such that men with nonamnestic or amnestic MCI have higher fasting plasma insulin than cognitively normal men, while women with amnestic MCI have lower fasting plasma insulin than cognitively normal women. Exploratory analyses suggest that APOE ε4 genotype may further influence the relationship between sex and insulin. Future research will help determine whether insulin dysregulation results in differential effects on vascular function and AD pathology as a function of sex and/or APOE genotype.

Low fasting serum insulin in Japanese alcohol consumers does not imply improved coronary risk factors

OBJECTIVE

The effects of alcohol consumption on coronary risk factors (CRFs) and insulin resistance (IR) have seemed equivocal in previous studies. This study aimed to clarify the implications of low fasting blood insulin observed in alcohol consumers as related to CRFs and IR.

METHODS

A cross-sectional observation in 2133 middle-aged healthy Japanese men for associations of increases in alcohol consumption, fasting serum insulin concentration and serum gammaglutamyltransferase (GGT) activity with the major CRFs of high systolic blood pressure (SBP), fasting serum glucose, triglycerides (TG), total- and LDL-cholesterol (tCh&LDLc) and low serum HDL-cholesterol (HDLc).

RESULTS

Increased alcohol consumption was related to higher SBP, serum GGT, glucose and HDLc, and lower serum LDLc and insulin. Although high serum insulin was significantly related to all of the CRFs in all nondrinkers, moderate drinkers consuming up to 59 ml of alcohol per day and excessive drinkers consuming more, the means of SBP, serum glucose and HDLc were significantly higher and serum LDLc was lower in drinkers than in nondrinkers at any level of serum insulin, indicating that the good and bad profiles of CRFs in alcohol consumers are independent of their low fasting serum insulin. High serum GGT related to increased alcohol consumption and/or body weight was significantly associated with high serum insulin and all of the CRFs in all categories of alcohol consumption.

CONCLUSIONS

Low fasting serum insulin observed in drinkers does not imply improved CRFs, and thus may not imply improved IR. High serum GGT may reflect increased IR in both drinkers and nondrinkers.

High prevalence of impaired fasting glucose in Chinese children and adolescents with prehypertension/hypertension

AIM

To assess the prevalence of impaired fasting glucose among Chinese children and adolescents with prehypertension/hypertension (PHP/HP), overweight/obesity (OW/OB) or both in the general population.

METHODS

In total, 3409 children and adolescents among the age group of 10-18 years were enrolled. These subjects were then divided into four groups: OW/OB, PHP/HP, OW/OB + PHP/HP and a control group. Fasting plasma glucose (FPG) and lipid levels were measured in children with a body mass index > or =85th percentile and/or blood pressure > or =90th percentile and in 100 subjects randomly selected from the control group. The oral glucose tolerance test was performed in all the subjects with fasting glucose > or =5.6 mmol/L.

RESULTS

Eighty-one impaired fasting glucose subjects and one girl with type 2 diabetes were identified. The prevalence of impaired fasting glucose in PHP/HP (7.03%) was not significantly different from that in the OW/OB + PHP/HP group (8.59%), but was higher than that in the OW/OB group (3.31%).

CONCLUSION

Although the American Diabetes Association does not recommend the FPG test for children and adolescents with PHP/HP, in this study, we found that children and adolescents with PHP/HP have a higher prevalence of impaired fasting glucose than those with OW/OB. Further validation of these findings is warranted and a type 2 diabetes screening protocol for Chinese children and adolescents needs to be established.

Role of the sympathetic and renin angiotensin systems in the glucose-induced increase of blood pressure in rats

The pressor effect induced by acute hyperglycemia is not well understood, therefore, it was of interest to study the effect of intravenous glucose infusion on the mean arterial pressure of anesthetized Wistar rats. Animals received glucose (100 mg/kg/min, i.v.), mannitol or saline during 30 min, but only glucose increased the mean arterial pressure (about 40 mm Hg), plasma glucose, insulin and nitric oxide (NO). Pretreatment with reserpine or indorenate (a central antihypertensive) inhibited completely the pressor effect of glucose. Reserpine also decreased the plasma NO levels. Pretreatment with ramipril or with streptozotocin decreased the late phase of the glucose-induced pressor response and the NO levels, the latter treatment also abolishes insulin plasma concentrations. The present results suggest that the pressor effect induced by glucose has an early phase due to an increase of efferent sympathetic discharges and a delayed phase produced by the activation of the renin angiotensin system.

Carotid body dysfunction: The possible etiology of non-insulin dependent diabetes mellitus and essential hypertension

Carotid bodies are monitors of oxygen and glucose delivery to the brain. Faced with the threat of hypoxia or hypoglycemia carotid bodies initiate responses to counter the threat. General corrective action is to improve the perfusion by increasing the arterial blood pressure. Specific corrective actions are to stimulate ventilation to improve oxygen availability or to induce insulin resistance to raise blood glucose levels. Inappropriateness of response caused by misreading of hypoxia as hypoglycemia and hypoglycemia as hypoxia is observed experimentally and clinically. The response to all four types of hypoxia, namely, hypoxic, anemic, histotoxic and ischemic (or stagnant) hypoxia, is stimulation of ventilation and elevation of blood pressure. Ischemia produced by narrowing of the artery to the carotid body activates the carotid bodies. The activation produces hypertension, stimulation of ventilation and insulin resistance that manifests as non-insulin dependent diabetes mellitus. There is epidemiologic and necropsy evidence for the onset of atherosclerotic changes in childhood. Early atherosclerotic changes occurring in the region of carotid arteries and their bifurcation narrows the lumen of the arteries to the carotid bodies and produce hypo-perfusion of the carotid bodies. This ischemic hypoxia is a causative, or at least a permissive factor for hypertension and/or non-insulin dependent diabetes mellitus. It is suggested that neither non-insulin dependent diabetes mellitus causes hypertension nor hypertension causes diabetes mellitus, but both are caused by dysfunctional carotid bodies.

Association of Pro12Ala polymorphism of PPARgamma gene with insulin resistance and related diseases

To clarify the contribution of the Pro12Ala polymorphism of the peroxisome proliferator-activated receptor gamma (PPARgamma) gene to susceptibility to insulin resistance and related diseases, 505 unrelated Japanese subjects were investigated, including 175 normotensive non-diabetic (NN) subjects, 125 normotensive diabetic (ND) subjects, 102 hypertensive non-diabetic (HN) subjects, and 103 hypertensive diabetic (HD) subjects. Ala phenotype frequency was lowest in patients with both type 2 diabetes and hypertension (3.9% in HD group), followed by patients with either one of these conditions (5.6% in ND group, 7.8% in HN group), and highest in subjects without these conditions (9.7% in NN group). When stratified by hypertensive status, the Ala phenotype was negatively associated with diabetes, giving an odds ratio of 0.53 (95% confidence interval: 0.25-1.09). In contrast, when stratified by diabetic status, the odds ratio of the Ala phenotype for hypertension was 0.75 (95% confidence interval: 0.37-1.54). In non-diabetic hypertensive subjects, glucose and insulin levels during oral glucose tolerance test as well as M-value estimated by glucose-clamp test were not significantly different according to the genotype. The data suggest a contribution of the Pro12Ala polymorphism of PPARgamma to genetic susceptibility to type 2 diabetes mellitus and hypertension, but not to insulin sensitivity in hypertensive subjects.

Alcohol consumption, homeostasis model assessment indices and blood pressure in middle-aged healthy men

A total of 1595 middle-aged healthy men consuming alcohol up to 120 ml per day and 538 without alcohol consumption were recruited from an occupational population, and their insulin resistance (IR) and beta-cell function (BC) were measured using the homeostasis model assessment (HOMA-IR and HOMA-BC), and the associations with alcohol consumption, blood pressure (BP), and serum gamma-glutamyltransferase (GGT) levels were analysed cross-sectionally. Both HOMA-IR and HOMA-BC were decreased with increasing alcohol consumption, but HOMA-BC corresponding to a level of HOMA-IR was 4-10 and 8-20% lower in drinkers consuming less than 60 ml of alcohol per day and those consuming more, respectively, than in nondrinkers, suggesting an altered fasting serum insulin-glucose relationship in alcohol consumers. Although BP was higher and HOMA-IR was lower in alcohol consumers than in nonconsumers, BP was higher at higher HOMA-IR irrespective of alcohol consumption. Elevations of serum GGT were positively associated with BP and HOMA-IR in both alcohol consumers and nonconsumers. Multiple regression analyses in the subjects showed that elevated serum GGT was an independent contributor to HOMA-IR elevations, and both serum GGT and HOMA-IR were significantly related to BP elevations after adjusting for alcohol consumption, age, body mass index, cigarette consumption, and physical activity at leisure. Although cross-sectional observations do not provide evidence of causal association, the results suggest that elevated serum GGT in alcohol consumers relates to elevations of IR and that the elevated insulin resistance relates, at least partly, to BP elevations in alcohol consumers.

How the endothelium and its bone marrow-derived progenitors influence development of disease

The association between diseases accompanied by abnormal endothelial/vascular function (atherosclerosis, hypertension, diabetes mellitus, preeclampsia), and conditions characterized by increased tissue growth and normal endothelial/vascular function (cancer, placental size, birth length, adult height) could be caused by inherited characteristics of endothelial cells and their bone marrow-derived precursors. The genotype responsible for normal endothelial/precursor function could be modified by intrauterine and postnatal endothelial injury; telomere shortening caused by increased endothelial precursor proliferation in response to injury can result in premature endothelial senescence and a decreased precursor proliferative potential, thereby leading to an abnormal endothelial/precursor phenotype and the associated diseases. The individual endothelial/precursor phenotype could be established early in life and its changes in response to risk factors for diseases followed over time, thus providing a unique opportunity for identification and early institution of prophylactic and therapeutic interventions in diseases that cause most of the morbidity and mortality in advanced industrialized societies.