Hyperinsulinemia augments endothelin-1 protein expression and impairs vasodilation of human skeletal muscle arterioles

Loss of CEACAM1 in hepatocytes causes hepatic fibrosis

BACKGROUND

The role of insulin resistance in hepatic fibrosis in Metabolic dysfunction-Associated SteatoHepatitis (MASH) remains unclear. Carcinoembryonic Antigen-related Cell Adhesion Molecule1 protein (CEACAM1) promotes insulin clearance to maintain insulin sensitivity and repress de novo lipogenesis, as bolstered by the development of insulin resistance and steatohepatitis in AlbuminCre + Cc1fl/fl mice with liver-specific mouse gene encoding CEACAM1 protein (Ceacam1) deletion. We herein investigated whether these mice also developed hepatic fibrosis and whether hepatic CEACAM1 is reduced in patients with MASH at different fibrosis stages.

METHODS

AlbuminCre + Cc1fl/fl mice were fed a regular or a high-fat diet before their insulin metabolism and action were assessed during IPGTT, and their livers excised for histochemical, immunohistochemical and Western blot analysis. Sirius red staining was used to assess fibrosis, and media transfer was employed to examine whether mutant hepatocytes activated hepatic stellate cells (HSCs). Hepatic CEACAM1 protein levels in patients with varying disease stages were assessed by ELISA.

RESULTS

Hepatocytic deletion of Ceacam1 caused hyperinsulinemia-driven insulin resistance emanating from reduced hepatic insulin clearance. AlbuminCre + Cc1fl/fl livers showed inflammation, fibrosis and hepatic injury, with more advanced bridging and chicken-wire hepatic fibrosis under high-fat conditions. Media transferred from hepatocytes isolated from mutant mice activated control HSCs, likely owing to their elevated endothelin1 content. Interestingly, hepatic CEACAM1 levels were lower in the livers of patients with MASH and declined gradually with advanced fibrosis stage.

CONCLUSIONS

Hepatic CEACAM1 levels declined with progression of MASH in humans. The phenotype of AlbuminCre + Cc1fl/fl mice assigned a key role to CEACAM1 loss from hepatocytes in hepatic fibrosis independently of other liver cells.

Evaluation of glomerular hemodynamic changes by sodium-glucose-transporter 2 inhibition in type 2 diabetic rats using in vivo imaging

The mechanisms responsible for glomerular hemodynamic regulation with sodium-glucose co-transporter 2 (SGLT2) inhibitors in kidney disease due to type 2 diabetes remain unclear. Therefore, we investigated changes in glomerular hemodynamic function using an animal model of type 2 diabetes, treated with an SGLT2 inhibitor alone or in combination with a renin-angiotensin-aldosterone system inhibitor using male Zucker lean (ZL) and Zucker diabetic fatty (ZDF) rats. Afferent and efferent arteriolar diameter and single-nephron glomerular filtration rate (SNGFR) were evaluated in ZDF rats measured at 0, 30, 60, 90, and 120 minutes after the administration of a SGLT2 inhibitor (luseogliflozin). Additionally, we assessed these changes under the administration of the adenosine A1 receptor (A1aR) antagonist (8-cyclopentyl-1,3-dipropylxanthine), along with coadministration of luseogliflozin and an angiotensin II receptor blocker (ARB), telmisartan. ZDF rats had significantly increased SNGFR, and afferent and efferent arteriolar diameters compared to ZL rats, indicating glomerular hyperfiltration. Administration of luseogliflozin significantly reduced afferent vasodilatation and glomerular hyperfiltration, with no impact on efferent arteriolar diameter. Urinary adenosine levels were increased significantly in the SGLT2 inhibitor group compared to the vehicle group. A1aR antagonism blocked the effect of luseogliflozin on kidney function. Co-administration of the SGLT2 inhibitor and ARB decreased the abnormal expansion of glomerular afferent arterioles, whereas the efferent arteriolar diameter was not affected. Thus, regulation of afferent arteriolar vascular tone via the A1aR pathway is associated with glomerular hyperfiltration in type 2 diabetic kidney disease.

Plasma undercarboxylated osteocalcin dynamics with glycemic stress reflects insulin sensitivity and beta-cell function in humans with and without T2DM

This study aimed to better understand the relationship between bone-related biomarkers and nutrient stress in the context of metabolic health. We investigated plasma osteocalcin (OC) during an oral glucose challenge and experimental hyperinsulinemia in Type 2 diabetes (T2DM) and lean healthy controls (LHC). Older individuals with obesity and T2DM (n = 9) and young LHCs (n = 9) underwent a 75g oral glucose tolerance test (OGTT) and a 40 mU/m2/min hyperinsulinemic-euglycemic clamp. Plasma undercarboxylated OC (ucOC) and total OC were measured at baseline, 60mins, and 120mins of the OGTT and clamp via ELISA. In addition, plasma alkaline phosphatase (ALP), leptin, adiponectin, Vitamin D and insulin were measured and indices of insulin sensitivity and β-cell function were derived. The T2DM group had lower (p<0.05) ucOC and ucOC:total OC ratio than LHC during both the OGTT and clamp. Further, baseline ucOC was positively correlated to indices of β-cell function and negatively correlated to indices of insulin resistance when both groups were combined (all p<0.05). Suppression of OC observed in T2DM may be related to glucose intolerance and insulin resistance. Similarly, our data suggest that the observed phenotypic differences between groups are likely a product of long-term glucose dysregulation rather than acute flux in glucose or insulin.

Adiposomes from Obese-Diabetic Individuals Promote Endothelial Dysfunction and Loss of Surface Caveolae

Glycosphingolipids (GSLs) are products of lipid glycosylation that have been implicated in the development of cardiovascular diseases. In diabetes, the adipocyte microenvironment is characterized by hyperglycemia and inflammation, resulting in high levels of GSLs. Therefore, we sought to assess the GSL content in extracellular vesicles derived from the adipose tissues (adiposomes) of obese-diabetic (OB-T2D) subjects and their impact on endothelial cell function. To this end, endothelial cells were exposed to adiposomes isolated from OB-T2D versus healthy subjects. Cells were assessed for caveolar integrity and related signaling, such as Src-kinase and caveolin-1 (cav-1) phosphorylation, and functional pathways, such as endothelial nitric oxide synthase (eNOS) activity. Compared with adiposomes from healthy subjects, OB-T2D adiposomes had higher levels of GSLs, especially LacCer and GM3; they promoted cav-1 phosphorylation coupled to an obvious loss of endothelial surface caveolae and induced eNOS-uncoupling, peroxynitrite generation, and cav-1 nitrosylation. These effects were abolished by Src kinase inhibition and were not observed in GSL-depleted adiposomes. At the functional levels, OB-T2D adiposomes reduced nitric oxide production, shear response, and albumin intake in endothelial cells and impaired flow-induced dilation in healthy arterioles. In conclusion, OB-T2D adiposomes carried a detrimental GSL cargo that disturbed endothelial caveolae and the associated signaling.

Glyoxalase I is a novel target for the prevention of metabolic derangement

Obesity prevalence in the US has nearly tripled since 1975 and a parallel increase in prevalence of type 2 diabetes (T2D). Obesity promotes a myriad of metabolic derangements with insulin resistance (IR) being perhaps the most responsible for the development of T2D and other related diseases such as cardiovascular disease. The precarious nature of IR development is such that it provides a valuable target for the prevention of further disease development. However, the mechanisms driving IR are numerous and complex making the development of viable interventions difficult. The development of metabolic derangement in the context of obesity promotes accumulation of reactive metabolites such as the reactive alpha-dicarbonyl methylglyoxal (MG). MG accumulation has long been appreciated as a marker of disease progression in patients with T2D as well as the development of diabetic complications. However, recent evidence suggests that the accumulation of MG occurs with obesity prior to T2D onset and may be a primary driving factor for the development of IR and T2D. Further, emerging evidence also suggests that this accumulation of MG with obesity may be a result in a loss of MG detoxifying capacity of glyoxalase I. In this review, we will discuss the evidence that posits MG accumulation because of GLO1 attenuation is a novel target mechanism of the development of metabolic derangement. In addition, we will also explore the regulation of GLO1 and the strategies that have been investigated so far to target GLO1 regulation for the prevention and treatment of metabolic derangement.

Reduced endothelial caveolin-1 underlies deficits in brain insulin signalling in type 2 diabetes

Patients with type 2 diabetes exhibit severe impairments in insulin signalling in the brain and are five times more likely to develop Alzheimer's disease. However, what leads to these impairments is not fully understood. Here, we show reduced expression of endothelial cell caveolin-1 (Cav-1) in the db/db (Leprdb) mouse model of type 2 diabetes. This reduction correlated with alterations in insulin receptor expression and signalling in brain microvessels as well as brain parenchyma. These findings were recapitulated in the brains of endothelial cell-specific Cav-1 knock-out (Tie2Cre; Cav-1fl/fl) mice. Lack of Cav-1 in endothelial cells led to reduced response to insulin as well as reduced insulin uptake. Furthermore, we observed that Cav-1 was necessary for the stabilization of insulin receptors in lipid rafts. Interactome analysis revealed that insulin receptor interacts with Cav-1 and caveolae-associated proteins, insulin-degrading enzyme and the tight junction protein Zonula Occludence-1 in brain endothelial cells. Restoration of Cav-1 in Cav-1 knock-out brain endothelial cells rescued insulin receptor expression and localization. Overall, these results suggest that Cav-1 regulates insulin signalling and uptake by brain endothelial cells by modulating IR-α and IR-β localization and function in lipid rafts. Furthermore, depletion of endothelial cell-specific Cav-1 and the resulting impairment in insulin transport leads to alteration in insulin signalling in the brain parenchyma of type 2 diabetics.

Hyperinsulinemia Impaired Coronary Collateral Circulation in Patients with Chronic Total Coronary Occlusion

Background and Objectives

Hyperinsulinemia impaired cardiovascular system and endothelial function in the population. The purpose of this study was to explore the relationship between hyperinsulinemia and coronary collateral circulation in patients with chronic total coronary occlusion.

Methods

Patients with stable angina and at least one total coronary occlusion were enrolled in this study. Collateral grade was determined according to Rentrop's classification. Patients were divided into a good coronary collateral circulation (CCC) group (grade 2 or 3 collateral vessels, n = 223) and a poor CCC group (grade 0 or 1 collateral vessels, n = 115). Fasting insulin level (FINS) and fasting glucose level (FBS) were measured. Endothelial function evaluated by flow-mediated dilation (FMD).

Results

Serum FINS level was significantly increased in the poor CCC group (P < 0.01). Patients in the poor CCC group had higher levels of FBS, HbA1C, and homeostasis model assessment for insulin resistance (HOMA-IR) than patients in the good CCC group. The poor CCC group also had lower levels of FMD, lower LVEF and higher syntax scores than the good CCC group. Hyperinsulinemia (T3, FINS ≥15.22 μIU/mL) increased OR for the incidence of the poor CCC group (OR 2.419, 95% CI 1.780-3.287) in multivariate analysis. Multivariate logistic regression also revealed that diabetes, HbA1c, HOMA-IR, HDL-C and Syntax score were independent predictors of poor CCC (all P < 0.05).

Conclusion

Hyperinsulinemia is a valuable predictor of poor collateral formation in patients with chronic total coronary occlusion.

Neutralization of excessive CCL28 improves wound healing in diabetic mice

Introduction: Chronic, non-healing skin wounds such as diabetic foot ulcers (DFUs) are common in patients with type 2 diabetes mellitus (T2DM) and often result in limb amputation and even death. However, mechanisms by which T2DM and inflammation negatively impact skin wound healing remains poorly understood. Here we investigate a mechanism by which an excessive level of chemokine CCL28, through its receptor CCR10, impairs wound healing in patients and mice with T2DM. Methods & Results: Firstly, a higher level of CCL28 was observed in skin and plasma in both patients with T2DM, and in obesity-induced type 2 diabetic db/db mice. Compared with WT mice, adipose tissue from db/db mice released 50% more CCL28, as well as 2- to 3-fold more IL-1β, IL-6, and TNF-α, and less VEGF, as determined by ELISA measurements. Secondly, overexpression of CCL28 with adenovirus (Adv-CCL28) caused elevation of proinflammatory cytokines as well as CCR10 expression and also reduced eNOS expression in the dorsal skin of WT mice as compared with control Adv. Thirdly, topical application of neutralizing anti-CCL28 Ab dose-dependently accelerated wound closure and eNOS expression, and decreased IL-6 level, with an optimal dose of 1 μg/wound. In addition, mRNA levels of eNOS and anti-inflammatory cytokine IL-4 were increased as shown by real-time RT-PCR. The interaction between eNOS and CCR10 was significantly reduced in diabetic mouse wounds following application of the optimal dose of anti-CCL28 Ab, and eNOS expression increased. Finally, enhanced VEGF production and increased subdermal vessel density as indicated by CD31 immunostaining were also observed with anti-CCL28 Ab. Discussion: Taken together, topical application of neutralizing anti-CCL28 Ab improved dorsal skin wound healing by reducing CCR10 activation and inflammation in part by preventing eNOS downregulation, increasing VEGF production, and restoring angiogenesis. These results indicate anti-CCL28 Ab has significant potential as a therapeutic strategy for treatment of chronic non-healing diabetic skin wounds such as DFUs.

Obesity-Associated Vitamin D Deficiency Correlates with Adipose Tissue DNA Hypomethylation, Inflammation, and Vascular Dysfunction

Vitamin D (VD) deficiency is a hallmark of obesity and vascular dysfunction. We sought to test the hypothesis that VD deficiency may contribute to obesity-related vascular dysfunction by inducing adipokine hypomethylation and augmented expression. To this end, we collected blood and adipose tissues (ATs) from a cohort of 77 obese participants who were classified as having mild, moderate, or severe VD deficiency. The body composition, vascular reactivity, cardiometabolic profiles, and DNA methylation of 94 inflammation-related adipokines were measured. Our results show that higher degrees of VD deficiency were associated with lower DNA methylation and induced the expression of inflammatory adipokines such as B-cell lymphoma 6 (BCL6), C-X-C Motif Chemokine Ligand 8 (CXCL8), histone deacetylase 5 (HDAC5), interleukin 12A (IL12A), and nuclear factor κB (NFκB) in the ATs. They were also associated with higher BMI and total and visceral fat mass, impaired insulin sensitivity and lipid profiles, AT hypoxia, and higher concentrations of circulating inflammatory markers. Moderate and severe VD deficiency correlated with impaired vasoreactivity of the brachial artery and AT-isolated arterioles, reduced nitric oxide generation, and increased arterial stiffness. In a multivariate regression analysis, the VD deficiency level strongly predicted the adipokine methylation score, systemic inflammation, and microvascular dysfunction. In conclusion, our findings suggest that VD deficiency is a possible contributor to obesity-related adipokine hypomethylation, inflammation, and vascular dysfunction.

The metabolic phenotype of the patient influences the reduction in carotid intima-media thickness achieved following metabolic surgery

Objectives

To determine whether metabolic phenotype is associated with the change in carotid intima-media thickness (CIMT) in patients undergoing bariatric /metabolic surgery (BMS).

Methods

We performed a case-control study of BMS candidates who had metabolically unhealthy obesity (MUO) or metabolically healthy obesity (MHO). We measured the change in CIMT during the 9 months following BMS. The plasma tumor necrosis factor-α, interleukin-1β, adiponectin, leptin, nitric oxide (NO), vascular endothelial growth factor A (VEGF-A), and malondialdehyde concentrations were determined, adipocyte area was measured histologically, and adipose tissue area was estimated using computed tomography.

Results

Fifty-six patients (mean age 44.5 years, mean body mass index 44.9 kg/m2, 53% women, and 53% had MUO) were studied. Nine months following BMS, the MUO phenotype was not associated with a significant reduction in CIMT, and that of the MHO group was larger. In addition, fewer participants achieved a 10% reduction in CIMT in the MUO group. A CIMT reduction was associated with lower VEGF-A and NO in the MUO group, while that in the MHO group was associated with a higher NO concentration.

Conclusion

The metabolic phenotype of patients may influence their change in CIMT following BMS, probably through circulating vasodilatory and pro-inflammatory molecules.

Inhibition of CCL28/CCR10-Mediated eNOS Downregulation Improves Skin Wound Healing in the Obesity-Induced Mouse Model of Type 2 Diabetes

Chronic, nonhealing skin wounds, such as diabetic foot ulcers (DFUs), are common in patients with type 2 diabetes. Here, we investigated the role of chemokine (C-C motif) ligand 28 (CCL28) and its receptor C-C chemokine receptor type 10 (CCR10) in downregulation of endothelial nitric (NO) oxide synthase (eNOS) in association with delayed skin wound healing in the db/db mouse model of type 2 diabetes. We observed reduced eNOS expression and elevated CCL28/CCR10 levels in dorsal skin of db/db mice and subdermal leg biopsy specimens from human subjects with type 2 diabetes. Further interrogation revealed that overexpression of CCR10 reduced eNOS expression, NO bioavailability, and tube formation of human dermal microvascular endothelial cells (HDMVECs) in vitro, which was recapitulated in mouse dorsal skin. In addition, incubation of HDMVECs with CCL28 led to internalization of the CCR10/eNOS complex and colocalization with lysosome-associated membrane protein 1. Finally, topical application of myristoylated CCR10 binding domain 7 amino acid (Myr-CBD7) peptide prevented CCR10-eNOS interaction and subsequent eNOS downregulation, enhanced eNOS/NO levels, eNOS/VEGF-R2+ microvessel density, and blood perfusion, reduced inflammatory cytokine levels, and importantly, decreased wound healing time in db/db mice. Thus, endothelial cell CCR10 activation in genetically obese mice with type 2 diabetes promotes eNOS depletion and endothelial dysfunction, and targeted disruption of CCR10/eNOS interaction improves wound healing.

DNA Hypomethylation as a Potential Link between Excessive Alcohol Intake and Cardiometabolic Dysfunction in Morbidly Obese Adults

A large percentage of obese patients in the United States suffer a comorbid substance use disorder, mainly alcohol use. Alcohol consumption interferes with the absorption of dietary methyl donors such as folate required for the one-carbon metabolism pathway and subsequently for DNA methylation. In this study, we assessed the association between alcohol consumption and DNA methylation in obese subjects. We obtained visceral adipose tissue (VAT) biopsies from bariatric patients. DNA methylation of 94 genes implicated in inflammation and immunity were analyzed in VAT in relation to alcohol consumption data obtained via questionnaires. Vasoreactivity was measured in the brachial artery and the VAT-isolated arterioles. Pro-inflammatory genes were significantly hypomethylated in the heavy drinking category correlating with higher levels of circulating inflammatory cytokines. Alcohol consumption correlated positively with body mass index (BMI), fat percentage, insulin resistance, impaired lipid profile, and systemic inflammation and negatively with plasma folate and vitamin B12, inflammatory gene DNA methylation, and vasoreactivity. In conclusion, these data suggest that alcohol intake is associated with lower DNA methylation and higher inflammation and cardiometabolic risk in obese individuals.

Insulin antibody as a biomarker to monitor the development of type 2 diabetes in county hospitals in China

Background

The significance of insulin antibody (IA) detection in type 2 diabetes mellitus (T2DM) has received scant attention from county hospitals in China. We aimed to introduce exogenous IA positive rate and its relative factors in T2DM treated with insulin in Xiangshan County of Ningbo City, analyzing the immunogenicity of different kinds of insulin.

Methods

Patients who were residents from the Danxi community and six towns (Dongchen, Xizhou, Maoyang, Sizhoutou, Juexi, and Qiangtou) in Xiangshan County and diagnosed with T2DM and treated with insulins at Xiangshan Hospital of TCM Medical and Health Group between August 2019 and June 2020 were identified. Those who met the eligibility criteria were included and assigned to the IA-positive or IA-negative group. The immunogenicity of different insulins was compared between the two groups.

Results

Among 992 patients, 781 were eligible for IA detection, and 40.2% of them were IA positive. Blood IA was closely associated with fasting and 2-h glucose, insulin, and C peptide levels and higher insulin dosage. Patients receiving basal insulin treatment showed significantly lower blood IA than those treated with mixed human insulin, premixed human insulins, rapid-acting analogs, or a combination of basal and rapid-acting analogs.

The Effect of Rye-Based Foods on Postprandial Plasma Insulin Concentration: The Rye Factor

Consumption of whole grain has been associated with lower incidence of type-2 diabetes, cardiovascular disease and their risk factors including improved glycemic control. In comparison with other whole grain products, rye bread has been shown to induce lower insulin response in the postprandial phase, without affecting the glucose response. This phenomenon has been referred to as the “rye factor” and is being explored in this review where we summarize the findings from meal and extended meal studies including rye-based foods. Overall, results from intervention studies showed that rye-based foods vs. (wheat) control foods had positive effect on both insulin and glucose responses in the postprandial phase, rather than on insulin alone. Mechanistic studies have shown that the rye factor phenomenon might be due to slowing of the glucose uptake in the intestine. However, this has also been shown for wheat-based bread and is likely an effect of structural properties of the investigated foods rather than the rye per se. More carefully controlled studies where standardized structural properties of different cereals are linked to the postprandial response are needed to further elucidate the underlying mechanisms and determinants for the effect of specific cereals and product traits on postprandial glycemic control.

High Intensity Acute Aerobic Exercise Elicits Alterations in Circulating and Skeletal Muscle Tissue Expression of Neuroprotective Exerkines

Background: Cathepsin B (CTSB) and brain derived neurotrophic factor (BDNF) are increased with aerobic exercise (AE) and skeletal muscle has been identified as a potential source of secretion. However, the intensity of AE and the potential for skeletal muscle contributions to circulating CTSB and BDNF have not been fully studied in humans. Objective: Determine the effects of AE intensity on circulating and skeletal muscle CTSB and BDNF expression profiles. Methods: Young healthy subjects (n = 16) completed treadmill-based AE consisting of VO2max and calorie-matched acute AE sessions at 40%, 65% and 80% VO2max. Fasting serum was obtained before and 30-minutes after each bout of exercise. Skeletal muscle biopsies (vastus lateralis) were taken before, 30-minutes and 3-hours after the 80% bout. Circulating CTSB and BDNF were assayed in serum. CTSB protein, BDNF protein and mRNA expression were measured in skeletal muscle tissue. Results: Serum CTSB increased by 20±7% (p = 0.02) and 30±18% (p = 0.04) after 80% and VO2max AE bouts, respectively. Serum BDNF showed a small non-significant increase (6±3%; p = 0.09) after VO2max. In skeletal muscle tissue, proCTSB increased 3 h-post AE (87±26%; p <  0.01) with no change in CTSB gene expression. Mature BDNF protein decreased (31±35%; p = 0.03) while mRNA expression increased (131±41%; p <  0.01) 3 h-post AE. Skeletal muscle fiber typing revealed that type IIa and IIx fibers display greater BDNF expression compared to type I (p = 0.02 and p <  0.01, respectively). Conclusions: High intensity AE elicits greater increases in circulating CTSB compared with lower intensities. Skeletal muscle protein and gene expression corroborate the potential role of skeletal muscle in generating and releasing neuroprotective exerkines into the circulation. NEW AND NOTEWORTHY: 1) CTSB is enriched in the circulation in an aerobic exercise intensity dependent manner. 2) Skeletal muscle tissue expresses both message and protein of CTSB and BDNF. 3) BDNF is highly expressed in glycolytic skeletal muscle fibers.

Plasma FGF21 concentrations are regulated by glucose independently of insulin and GLP-1 in lean, healthy humans

BACKGROUND

Fibroblast growth factor 21 (FGF21) treatment improves metabolic homeostasis in diverse species, including humans. Physiologically, plasma FGF21 levels increase modestly after glucose ingestion, but it is unclear whether this is mediated by glucose itself or due to a secondary effect of postprandial endocrine responses. A refined understanding of the mechanisms that control FGF21 release in humans may accelerate the development of small-molecule FGF21 secretagogues to treat metabolic disease. This study aimed to determine whether FGF21 secretion is stimulated by elevations in plasma glucose, insulin, or glucagon-like peptide-1 (GLP-1) in humans.

METHODS

Three groups of ten healthy participants were included in a parallel-group observational study. Group A underwent a hyperglycemic infusion; Group B underwent a 40 mU/m²/min hyperinsulinemic euglycemic clamp; Group C underwent two pancreatic clamps (to suppress endogenous insulin secretion) with euglycemic and hyperglycemic stages with an infusion of either saline or 0.5 pmol/kg/min GLP-1. Plasma FGF21 concentrations were measured at baseline and during each clamp stage by ELISA.

RESULTS

Plasma FGF21 was unaltered during hyperglycemic infusion and hyperinsulinemic euglycemic clamps, compared to baseline. FGF21 was, however, increased by hyperglycemia under pancreatic clamp conditions (P < 0.05), while GLP-1 infusion under pancreatic clamp conditions did not change circulating FGF21 levels.

CONCLUSION

Increases in plasma FGF21 are likely driven directly by changes in plasma glucose independent of changes in insulin or GLP-1 secretion. Ecologically valid postprandial investigations are now needed to confirm our observations from basic science infusion models.

CD147 Levels in Blood and Adipose Tissues Correlate with Vascular Dysfunction in Obese Diabetic Adults

CD147 is a glycoprotein that stimulates the production of matrix metalloproteinases (MMPs), known contributors to cardiovascular risk. The activity of CD147 protein depends on its glycosylation. However, it is unclear whether CD147 protein expression or glycosylation are influenced by the diabetic milieu characterized by hyperglycemia and abundant glycation-end-products (AGEs). We examined the circulating and visceral adipose tissue (VAT) levels of CD147 and their correlation with vascular function in obese, obese diabetic, and non-obese controls (n = 40, each). The circulating levels of CD147 and the glycosylated CD147 protein in VAT were considerably higher in obese, particularly obese diabetic subjects compared to controls. Obese diabetics had the lowest brachial and arteriolar vasoreactivity and the highest carotid pulse-wave velocity (PWV, a measure of arterial stiffness) among the three groups. CD147 correlated positively with body mass index (BMI), total and visceral fat mass, PWV, and plasma levels of glucose, insulin, MMPs, and AGEs and negatively with brachial artery and VAT-arteriolar vasoreactivity and nitric oxide production. Multivariate regression revealed that BMI, body fat mass, insulin, and glucose levels significantly predicted CD147. Our data suggest that higher levels of CD147 in obese subjects, particularly those with diabetes, are linked to vascular dysfunction and several cardiometabolic risk factors.

Endothelin-1 levels are decreased in pediatric Type 1 diabetes and negatively correlate with the carotid intima media thickness

AIMS

Better understanding of the timeline and risk factors for the appearance of complications in pediatric Type-1-diabetes is key for developing prevention strategies. We studied endothelial markers and their determinants in adolescents with Type-1-diabetes at different time points from diagnosis.

METHODS

A cross-sectional study of 58 adolescents, mean age 15.0 ± 2.4 years; 20 with recent-onset Type-1-diabetes, 20 with over 7 years of Type-1-diabetes and 18 controls. Clinical and biochemical data were collected. Fingertip arterial reactive hyperemia (EndoPAT) and carotid intima-media-thickness (cIMT) were measured to assess endothelial function and structure.

RESULTS

Compared to controls, individuals with prolonged Type-1-diabetes had higher mean cIMT (0.49 ± 0.07 mm vs. 0.43 ± 0.05 mm p = 0.021) and maximal cIMT (0.61 ± 0.08 mm 0.52 ± 0.08 mm, p = 0.025). Endothelin-1 levels were significantly lower in subjects with prolonged Type-1-diabetes (1.2 ± 1.0 pg/ml) compared to controls (3.0 ± 1.7, p = 0.008 pg/ml); they negatively correlated with the mean cIMT (c = - 0.291, p = 0.031) and mean 6 months hemoglobin A1c (c = - 0.301, p = 0.022) and positively correlated with mean c-peptide levels (c = 0.356, p = 0.006) and the weekly exercise time (c = 0.485, p < 0.001). Endothelin-1 levels did not correlate with EndoPAT results.

CONCLUSIONS

Our results suggest that the early years after the diagnosis of Type-1-diabetes are an important window for prevention of arterial damage in the pediatric population. The trajectories of relationships of Endothelin-1 with metabolic and vascular measures were opposite from the anticipated, yet consistent. Endothelin-1 related indirectly to adverse measures and directly to favorable measures. Decreased Endothelin-1 levels might reflect early stages in endothelial impairment in Type-1-diabetes, yet its' exact role in the development of complications is yet to be unraveled.

Adipose Tissue Hypoxia Correlates with Adipokine Hypomethylation and Vascular Dysfunction

Obesity is characterized by the accumulation of dysfunctional adipose tissues, which predisposes to cardiometabolic diseases. Our previous in vitro studies demonstrated a role of hypoxia in inducing adipokine hypomethylation in adipocytes. We sought to examine this mechanism in visceral adipose tissues (VATs) from obese individuals and its correlation with cardiometabolic risk factors. We propose an involvement of the hypoxia-inducible factor, HIF1α, and the DNA hydroxymethylase, TET1. Blood samples and VAT biopsies were obtained from obese and non-obese subjects (n = 60 each) having bariatric and elective surgeries, respectively. The analyses of VAT showed lower vascularity, and higher levels of HIF1α and TET1 proteins in the obese subjects than controls. Global hypomethylation and hydroxymethylation were observed in VAT from obese subjects along with promoter hypomethylation of several pro-inflammatory adipokines. TET1 protein was enriched near the promotor of the hypomethylated adipokines. The average levels of adipokine methylation correlated positively with vascularity and arteriolar vasoreactivity and negatively with protein levels of HIF1α and TET1 in corresponding VAT samples, serum and tissue inflammatory markers, and other cardiometabolic risk factors. These findings suggest a role for adipose tissue hypoxia in causing epigenetic alterations, which could explain the increased production of adipocytokines and ultimately, vascular dysfunction in obesity.

Exercise Training Improves Functions of Endothelial Progenitor Cells in Patients with Metabolic Syndrome

Fundamento

As células progenitoras endoteliais (CPEs) desempenham um papel importante na manutenção da função endotelial. A síndrome metabólica (SM) está associada à disfunção das CPEs. Embora o exercício físico tenha um impacto benéfico na atividade das CPEs, seu mecanismo ainda não está completamente esclarecido.

Objetivo

O objetivo deste estudo é investigar os efeitos do exercício físico nas funções das CPEs e os mecanismos subjacentes em pacientes com SM.

Métodos

Os voluntários com SM foram divididos em grupo exercício (n=15) e grupo controle (n=15). Antes e após 8 semanas de treinamento físico, as CPEs foram isoladas do sangue periférico. Foram feitos o ensaio de unidades formadoras de colônias (UFC), o ensaio de formação de tubos, a expressão proteica do óxido nítrico sintase endotelial (eNOS), da fosfatidilinositol-3-quinase (PI3-K) e da proteína quinase B (AKT). Considerou-se um valor de probabilidade <0,05 para indicar significância estatística.

Resultados

Após 8 semanas, o número de UFCs aumentou significativamente no grupo exercício em comparação com o grupo controle (p<0,05). Além disso, observamos uma diminuição significativa do modelo de avaliação da homeostase da resistência à insulina (HOMA-IR), endotelina-1, proteína C reativa de alta sensibilidade e dos níveis de homocisteína no grupo exercício. A intervenção com exercícios também pode aumentar a capacidade de formação de tubos de CPEs e aumentar o nível de fosforilação de eNOS, PI3-K e AKT.

Conclusão

O exercício físico aprimorou as funções das CPEs. O mecanismo pode estar relacionado ao exercício, ativando a via PI3-K/AKT/eNOS.

Regulation of hepatic fibrosis by carcinoembryonic antigen-related cell adhesion molecule 1

OBJECTIVE

NAFLD is a complex disease marked by cellular abnormalities leading to NASH. NAFLD patients manifest low hepatic levels of CEACAM1, a promoter of insulin clearance. Consistently, Cc1^-/- null mice displayed spontaneous hyperinsulinemia/insulin resistance and steatohepatitis. Liver-specific reconstitution of Ceacam1 reversed these metabolic anomalies in 8-month-old Cc1^-/-xliver+ mice fed a regular chow diet. The current study examined whether it would also reverse progressive hepatic fibrosis in mice fed a high-fat (HF) diet.

METHODS

3-Month-old mice were fed a high-fat diet for 3-5 months, and metabolic and histopathological analysis were conducted to evaluate their NASH phenotype.

RESULTS

Reconstituting CEACAM1 to Cc1^-/- livers curbed diet-induced liver dysfunction and NASH, including macrovesicular steatosis, lobular inflammation, apoptosis, oxidative stress, and chicken-wire bridging fibrosis. Persistence of hepatic fibrosis in HF-fed Cc1^-/- treated with nicotinic acid demonstrated a limited role for lipolysis and adipokine release in hepatic fibrosis caused by Ceacam1 deletion.

CONCLUSIONS

Restored metabolic and histopathological phenotype of HF-fed Cc1^{-/-xliver+xliver+} assigned a critical role for hepatic CEACAM1 in preventing NAFLD/NASH including progressive hepatic fibrosis.

INERTIA: A pilot study of the impact of progressive resistance training on blood pressure control in older adults with sarcopenia

Sarcopenia, and high blood pressure are highly prevalent, preventable conditions that pose significant burden for older adults and on the healthcare system. Current prevention and treatment of high blood pressure in sarcopenia, by non-pharmacological approaches remain limited and are far from optimal. Clinical trials and mechanistic studies provide encouraging evidence of a plausible therapeutic effect of progressive resistance training (PRT) on blood pressure in younger, and pre-hypertensive and hypertensive older adults. The impact of PRT on blood pressure has not been empirically tested in older adults with sarcopenia. This pilot study aims to provide effect size confidence intervals, clinical trial and intervention feasibility data, and procedural materials for a full-scale randomized controlled trial that will determine the efficacy of PRT intervention as a therapeutic strategy for blood pressure control in older adults with sarcopenia. Participants (N = 90) will be randomized to receive exercise educational materials or the PRT intervention consisting of 24 supervised exercise sessions over 12-weeks. Follow-up assessments will occur at 12-weeks and one-year later. The primary outcome is systolic blood pressure and diastolic blood pressure, analyzed separately. Microvascular mechanisms linking muscle (perfusion, strength, function) to changes in blood pressure will be explored at baseline and 12-weeks. This study will provide new evidence for the therapeutic effect of PRT as a non-pharmacological strategy for improving blood pressure. Insights gained may also inform of the potential role of muscle strength as a novel target for blood pressure control, and future exercise prescription guidelines related to muscle strengthening in high-risk older adults.

DNA methylation profile of genes involved in inflammation and autoimmunity correlates with vascular function in morbidly obese adults

Obesity is a major risk factor for cardiovascular disease. Blood-detected epigenetic profiles may serve as non-invasive clinically relevant biomarkers. Therefore, we investigated DNA methylation of genes involved in inflammation in peripheral blood of obese subjects and lean controls and their correlation with cardiometabolic measurements. We obtained blood and adipose tissue (AT) samples from bariatric patients (n = 24) and control adults (n = 24). AT-isolated arterioles were tested for flow-induced dilation (FID) and production of nitric oxide (NO) and reactive oxygen species (ROS). Brachial artery flow-mediated dilation (FMD) was measured via doppler ultrasound. Promoter methylation of 94 genes involved in inflammation and autoimmunity were analysed in whole-blood DNA in relation to vascular function and cardiometabolic risk factors. 77 genes had ahigher methylated fraction in the controls compare obese subjects and 28 proinflammatory genes were significantly hypomethylated in the obese individuals; on top of these genes are CXCL1, CXCL12, CXCL6, IGF2BP2, HDAC4, IL12A, and IL17RA. Fifteen of these genes had significantly higher mRNA in obese subjects compared to controls; on top of these genes are CXCL6, TLR5, IL6ST, EGR1, IL15RA, and HDAC4. Methylation % inversely correlated with BMI, total fat %, visceral fat%, blood pressure, fasting plasma insulin, serum IL6 and C-reactive protein, arteriolar ROS, and alcohol consumption and positive correlations with lean %, HDL, plasma folate and vitamin B12, arteriolar FID and NO production, and brachial FMD. Our results suggest that vascular dysfunction in obese adults may be attributed to asystemic hypomethylation and over expression of the immune-related genes.

Impact of Hyperinsulinemia on Long-Term Clinical Outcomes of Percutaneous Coronary Intervention in Patients without Diabetes Who Have Acute Myocardial Syndrome

BACKGROUND AND OBJECTIVES

Hyperinsulinemia plays a key role in the development of cardiovascular impairment in patients with metabolic syndrome. The aim of this study was to evaluate the influence of hyperinsulinemia on long-term clinical outcomes of percutaneous coronary intervention (PCI) in patients without diabetes mellitus who have acute myocardial syndrome (ACS).

METHODS

Between March 2016 and January 2019, we enrolled 468 patients with ACS and without diabetes mellitus who received primary PCI. Patients were divided into a low-insulin group (n = 157), medium-insulin group (n = 154), and high-insulin group (n = 157) according to tertiles of fasting insulin level. The primary endpoint was major adverse cardiac events (MACE; all-cause death, non-fatal myocardial infarction, target vessel revascularization [TVR]) at 24 months. The secondary endpoint was angina hospitalization.

RESULTS

Patients in the high-insulin group had an unfavorable prognosis, with a higher rate of MACE (34.39%) than the low-insulin group (22.29%) and medium-insulin group (23.37%) at 24 months (P < 0.05). This difference was mainly driven by the increase in TVR. The high-insulin group also had a higher rate of angina hospitalization than the low-insulin group. Cox proportional hazards regression showed that high-insulin level (hazard ratio [HR] 1.870, 95% confidence interval [CI] 1.202-2.909), small-vessel lesion (HR 1.713, 95% CI 1.111-2.642), bifurcation lesion (HR 3.394, 95% CI 2.033-5.067), SYNTAX score (HR 1.084, 95% CI 1.039-1.130), and stent length (HR 1.017, 95% CI 1.002-1.032) increased the incidence of MACE in patients with ACS and without diabetes who underwent PCI.

CONCLUSION

Hyperinsulinemia might be a valid predictor of clinical outcomes in patients with ACS undergoing PCI.

Greater Lower Limb Fatigability in People with Prediabetes than Controls

INTRODUCTION

The study purpose was to compare perceived fatigability and performance fatigability after high-velocity contractions with knee extensor muscles between people with prediabetes, people with type 2 diabetes (T2D), and controls without diabetes matched for age, body mass index, and physical activity.

METHODS

Twenty people with prediabetes (11 men, 9 women: 63.1 ± 6.0 yr, 26.9 ± 4.2 kg·m, 8030 ± 3110 steps per day), 39 with T2D (23 men, 16 women: 61.2 ± 8.5 yr, 29.4 ± 6.4 kg·m, 8440 ± 4220 steps per day), and 27 controls (13 men, 14 women: 58.1 ± 9.4 yr, 27.3 ± 4.3 kg·m, 8400 ± 3000 steps per day) completed the Fatigue Impact Scale as a measure of perceived fatigability and a fatigue protocol including 120 maximal-effort, high-velocity concentric contractions (MVCC; 1 contraction/3 s) with the knee extensors using a submaximal load (30% maximum) to quantify performance fatigability. Electrical stimulation was used to assess voluntary activation and contractile function of the knee extensor muscles before and after the fatigue protocol.

RESULTS

Fatigue Impact Scale scores were not different between people with prediabetes, people with T2D, and controls (12.5 ± 15.1, 18.3 ± 22.7, and 12.6 ± 18.6, respectively; P = 0.517). However, people with prediabetes had greater reductions in MVCC power during the fatigue protocol than did controls (31.8% ± 22.6% vs 22.1% ± 21.1%, P < 0.001), and both groups had lesser reductions than the T2D group (44.8% ± 21.9%, P < 0.001). Similarly, the prediabetes group had larger reductions in electrically evoked twitch amplitude than the control group (32.5% ± 24.9% vs 21.3% ± 33.0%, P < 0.001), but lesser reductions than those with T2D (44.0% ± 23.4%, P < 0.001). For all three groups, a greater decline in MVCC power was associated with larger reductions of twitch amplitude (r = 0.350, P < 0.001).

CONCLUSION

People with prediabetes have greater performance fatigability of the knee extensors due to contractile mechanisms compared with controls, although less performance fatigability than that of people with T2D.

Endothelial dysfunction due to selective insulin resistance in vascular endothelium: insights from mechanistic modeling

Previously, we have used mathematical modeling to gain mechanistic insights into insulin-stimulated glucose uptake. Phosphatidylinositol 3-kinase (PI3K)-dependent insulin signaling required for metabolic actions of insulin also regulates endothelium-dependent production of the vasodilator nitric oxide (NO). Vasodilation increases blood flow that augments direct metabolic actions of insulin in skeletal muscle. This is counterbalanced by mitogen-activated protein kinase (MAPK)-dependent insulin signaling in endothelium that promotes secretion of the vasoconstrictor endothelin-1 (ET-1). In the present study, we extended our model of metabolic insulin signaling into a dynamic model of insulin signaling in vascular endothelium that explicitly represents opposing PI3K/NO and MAPK/ET-1 pathways. Novel NO and ET-1 subsystems were developed using published and new experimental data to generate model structures/parameters. The signal-response relationships of our model with respect to insulin-stimulated NO production, ET-1 secretion, and resultant vascular tone, agree with published experimental data, independent of those used for model development. Simulations of pathological stimuli directly impairing only insulin-stimulated PI3K/Akt activity predict altered dynamics of NO and ET-1 consistent with endothelial dysfunction in insulin-resistant states. Indeed, modeling pathway-selective impairment of PI3K/Akt pathways consistent with insulin resistance caused by glucotoxicity, lipotoxicity, or inflammation predict diminished NO production and increased ET-1 secretion characteristic of diabetes and endothelial dysfunction. We conclude that our mathematical model of insulin signaling in vascular endothelium supports the hypothesis that pathway-selective insulin resistance accounts, in part, for relationships between insulin resistance and endothelial dysfunction. This may be relevant for developing novel approaches for the treatment of diabetes and its cardiovascular complications.

Hyperhomocysteinemia and Low Folate and Vitamin B12 Are Associated with Vascular Dysfunction and Impaired Nitric Oxide Sensitivity in Morbidly Obese Patients

There is a high prevalence of hyperhomocysteinemia that has been linked to high cardiovascular risk in obese individuals and could be attributed to poor nutritional status of folate and vitamin B12. We sought to examine the association between blood homocysteine (Hcy) folate, and vitamin B12 levels and vascular dysfunction in morbidly obese adults using novel ex vivo flow-induced dilation (FID) measurements of isolated adipose tissue arterioles. Brachial artery flow-mediated dilation (FMD) was also measured. Subcutaneous and visceral adipose tissue biopsies were obtained from morbidly obese individuals and non-obese controls. Resistance arterioles were isolated in which FID, acetylcholine-induced dilation (AChID), and nitric oxide (NO) production were measured in the absence or presence of the NO synthase inhibitor, L-NAME, Hcy, or the superoxide dismutase mimetic, TEMPOL. Our results demonstrated that plasma Hcy concentrations were significantly higher, while folate, vitamin B12, and NO were significantly lower in obese subjects compared to controls. Hcy concentrations correlated positively with BMI, fat %, and insulin levels but not with folate or vitamin B12. Brachial and arteriolar vasodilation were lower in obese subjects, positively correlated with folate and vitamin B12, and inversely correlated with Hcy. Arteriolar NO measurements and sensitivity to L-NAME were lower in obese subjects compared to controls. Finally, Hcy incubation reduced arteriolar FID and NO sensitivity, an effect that was abolished by TEMPOL. In conclusion, these data suggest that high concentrations of plasma Hcy and low concentrations of folate and vitamin B12 could be independent predictors of vascular dysfunction in morbidly obese individuals.

Extracellular Vesicles and Insulin Resistance: A Potential Interaction in Vascular Dysfunction

Insulin resistance plays a key role in cardiovascular complications associated with diabetes mellitus and hypertensive disorders. In states of insulin resistance several circulating factors may contribute to a defective insulin sensitivity in different tissues, including the vasculature. One of these factors influencing the vascular insulin resistance are the extracellular vesicles. The extracellular vesicles include exosomes, microvesicles, and apoptotic bodies which are released to the circulation by different vascular cells. Since the cargo of extracellular vesicles seems to be altered in metabolic complications associated with insulin resistance, these vesicles may be candidates contributing to vascular insulin resistance. Despite the studies linking insulin resistance signalling pathways with the vascular effect of extracellular vesicles, the involvement of these structures in vascular insulin resistance is a phenomenon that remains unclear.

Pathophysiologic mechanisms in diabetic kidney disease: A focus on current and future therapeutic targets

Diabetic kidney disease (DKD) is the primary cause of chronic kidney disease around the globe and is one of the main complications in patients with type 1 and 2 diabetes. The standard treatment for DKD is drugs controlling hyperglycemia and high blood pressure. Renin angiotensin aldosterone system blockade and sodium glucose cotransporter 2 (SGLT2) inhibition have yielded promising results in DKD, but many diabetic patients on such treatments nevertheless continue to develop DKD, leading to kidney failure and cardiovascular comorbidities. New therapeutic options are urgently required. We review here the promising therapeutic avenues based on insights into the mechanisms of DKD that have recently emerged, including mineralocorticoid receptor antagonists, SGLT2 inhibitors, glucagon-like peptide-1 receptor agonist, endothelin receptor A inhibition, anti-inflammatory agents, autophagy activators and epigenetic remodelling. The involvement of several molecular mechanisms in DKD pathogenesis, together with the genetic and epigenetic variability of this condition, makes it difficult to target this heterogeneous patient population with a single drug. Personalized medicine, taking into account the genetic and mechanistic variability, may therefore improve renal and cardiovascular protection in diabetic patients with DKD.

CCL28-induced CCR10/eNOS interaction in angiogenesis and skin wound healing

Chemokines and their receptors play important roles in vascular homeostasis, development, and angiogenesis. Little is known regarding the molecular signaling mechanisms activated by CCL28 chemokine via its primary receptor CCR10 in endothelial cells (ECs). Here, we test the hypothesis that CCL28/CCR10 signaling plays an important role in regulating skin wound angiogenesis through endothelial nitric oxide synthase (eNOS)-dependent Src, PI3K, and MAPK signaling. We observed nitric oxide (NO) production in human primary ECs stimulated with exogenous CCL28, which also induced direct binding of CCR10 and eNOS resulting in inhibition of eNOS activity. Knockdown of CCR10 with siRNA lead to reduced eNOS expression and tube formation suggesting the involvement of CCR10 in EC angiogenesis. Based on this interaction, we engineered a myristoylated 7 amino acid CCR10-binding domain (Myr-CBD7) peptide and showed that this can block eNOS interaction with CCR10, but not with calmodulin, resulting in upregulation of eNOS activity. Importantly, topical administration of Myr-CBD7 peptide on mouse dermal wounds not only blocked CCR10-eNOS interaction, but also enhanced expression of eNOS, CD31, and IL-4 with reduction of CCL28 and IL-6 levels associated with improved wound healing. These results point to a potential therapeutic strategy to upregulate NO bioavailability, enhance angiogenesis, and improve wound healing by disrupting CCL28-activated CCR10-eNOS interaction.

Chronic Elevation of Endothelin-1 Alone May Not Be Sufficient to Impair Endothelium-Dependent Relaxation

Endothelin-1 (ET-1) is a powerful vasoconstrictor peptide considered to be causally implicated in hypertension and the development of cardiovascular disease. Increased ET-1 is commonly associated with reduced NO bioavailability and impaired vascular function; however, whether chronic elevation of ET-1 directly impairs endothelium-dependent relaxation (EDR) remains elusive. Herein, we report that (1) prolonged ET-1 exposure (ie, 48 hours) of naive mouse aortas or cultured endothelial cells did not impair EDR or reduce eNOS (endothelial NO synthase) activity, respectively (P>0.05); (2) mice with endothelial cell-specific ET-1 overexpression did not exhibit impaired EDR or reduced eNOS activity (P>0.05); (3) chronic (8 weeks) pharmacological blockade of ET-1 receptors in obese/hyperlipidemic mice did not improve aortic EDR or increase eNOS activity (P>0.05); and (4) vascular and plasma ET-1 did not inversely correlate with EDR in resistance arteries isolated from human subjects with a wide range of ET-1 levels (r=0.0037 and r=-0.1258, respectively). Furthermore, we report that prolonged ET-1 exposure downregulated vascular UCP-1 (uncoupling protein-1; P<0.05), which may contribute to the preservation of EDR in conditions characterized by hyperendothelinemia. Collectively, our findings demonstrate that chronic elevation of ET-1 alone may not be sufficient to impair EDR.

Vitamin D Improves Nitric Oxide-Dependent Vasodilation in Adipose Tissue Arterioles from Bariatric Surgery Patients

There is a high prevalence of vitamin-D deficiency in obese individuals that could be attributed to vitamin-D sequestration in the adipose tissue. Associations between vitamin-D deficiency and unfavorable cardiometabolic outcomes were reported. However, the pathophysiological mechanisms behind these associations are yet to be established. In our previous studies, we demonstrated microvascular dysfunction in obese adults that was associated with reduced nitric oxide (NO) production. Herein, we examined the role of vitamin D in mitigating microvascular function in morbidly obese adults before and after weight loss surgery. We obtained subcutaneous (SAT) and visceral adipose tissue (VAT) biopsies from bariatric patients at the time of surgery (n = 15) and gluteal SAT samples three months post-surgery (n = 8). Flow-induced dilation (FID) and acetylcholine-induced dilation (AChID) and NO production were measured in the AT-isolated arterioles ± NO synthase inhibitor N(ω)-nitro-L-arginine methyl ester (L-NAME), hydrogen peroxide (H2O2) inhibitor, polyethylene glycol-modified catalase (PEG-CAT), or 1,25-dihydroxyvitamin D. Vitamin D improved FID, AChID, and NO production in AT-isolated arterioles at time of surgery; these effects were abolished by L-NAME but not by PEG-CAT. Vitamin-D-mediated improvements were of a higher magnitude in VAT compared to SAT arterioles. After surgery, significant improvements in FID, AChID, NO production, and NO sensitivity were observed. Vitamin-D-induced changes were of a lower magnitude compared to those from the time of surgery. In conclusion, vitamin D improved NO-dependent arteriolar vasodilation in obese adults; this effect was more significant before surgery-induced weight loss.

Persistent insulin signaling coupled with restricted PI3K activation causes insulin-induced vasoconstriction

Insulin modulates vasomotor tone through vasodilator and vasoconstrictor signaling pathways. The purpose of the present work was to determine whether insulin-stimulated vasoconstriction is a pathophysiological phenomenon that can result from a combination of persistent insulin signaling, suppressed phosphatidylinositol-3 kinase (PI3K) activation, and an ensuing relative increase in MAPK/endothelin-1 (ET-1) activity. First, we examined previously published work from our group where we assessed changes in lower-limb blood flow in response to an oral glucose tolerance test (endogenous insulin stimulation) in lean and obese subjects. The new analyses showed that the peak rise in vascular resistance during the postprandial state was greater in obese compared with lean subjects. We next extended on these findings by demonstrating that insulin-induced vasoconstriction in isolated resistance arteries from obese subjects was attenuated with ET-1 receptor antagonism, thus implicating ET-1 signaling in this constriction response. Last, we examined in isolated resistance arteries from pigs the dual roles of persistent insulin signaling and blunted PI3K activation in modulating vasomotor responses to insulin. We found that prolonged insulin stimulation did not alter vasomotor responses to insulin when insulin-signaling pathways remained unrestricted. However, prolonged insulinization along with pharmacological suppression of PI3K activity resulted in insulin-induced vasoconstriction, rather than vasodilation. Notably, such aberrant vascular response was rescued with either MAPK inhibition or ET-1 receptor antagonism. In summary, we demonstrate that insulin-induced vasoconstriction is a pathophysiological phenomenon that can be recapitulated when sustained insulin signaling is coupled with depressed PI3K activation and the concomitant relative increase in MAPK/ET-1 activity.NEW & NOTEWORTHY This study reveals that insulin-induced vasoconstriction is a pathophysiological phenomenon. We also provide evidence that in the setting of persistent insulin signaling, impaired phosphatidylinositol-3 kinase activation appears to be a requisite feature precipitating MAPK/endothelin 1-dependent insulin-induced vasoconstriction.

Endothelial Dysfunction: Is There a Hyperglycemia-Induced Imbalance of NOX and NOS?

NADPH oxidases (NOX) are enzyme complexes that have received much attention as key molecules in the development of vascular dysfunction. NOX have the primary function of generating reactive oxygen species (ROS), and are considered the main source of ROS production in endothelial cells. The endothelium is a thin monolayer that lines the inner surface of blood vessels, acting as a secretory organ to maintain homeostasis of blood flow. The enzymatic production of nitric oxide (NO) by endothelial NO synthase (eNOS) is critical in mediating endothelial function, and oxidative stress can cause dysregulation of eNOS and endothelial dysfunction. Insulin is a stimulus for increases in blood flow and endothelium-dependent vasodilation. However, cardiovascular disease and type 2 diabetes are characterized by poor control of the endothelial cell redox environment, with a shift toward overproduction of ROS by NOX. Studies in models of type 2 diabetes demonstrate that aberrant NOX activation contributes to uncoupling of eNOS and endothelial dysfunction. It is well-established that endothelial dysfunction precedes the onset of cardiovascular disease, therefore NOX are important molecular links between type 2 diabetes and vascular complications. The aim of the current review is to describe the normal, healthy physiological mechanisms involved in endothelial function, and highlight the central role of NOX in mediating endothelial dysfunction when glucose homeostasis is impaired.

Low-Fat Diet Designed for Weight Loss But Not Weight Maintenance Improves Nitric Oxide-Dependent Arteriolar Vasodilation in Obese Adults

Obesity is associated with microvascular dysfunction. While low-fat diet improves cardiovascular risk, its contributions on microvascular function, independent of weight loss, is unknown. We tested the hypothesis that nitric oxide (NO)-dependent vasodilation in microvessels is improved by low-fat diets designed for weight loss (LFWL) compared to low-fat weight maintenance (LFWM) diet. Obese adults were randomly assigned to either a LFWL diet (n = 11) or LFWM diet (n = 10) for six weeks. Microvessels were obtained from gluteal subcutaneous fat biopsies before and after the intervention for vascular reactivity measurements to acetylcholine (Ach) and flow, with and without L-NAME or indomethacin. Vascular and serum NO and C-reactive protein (CRP) were also measured. LFWL diet increased flow-induced (FID) and ACh-induced dilation (AChID); an effect that was inhibited by L-NAME. Conversely, LFWM diet did not affect FID or AChID. Indomethacin improved FID and AChID in the baseline and this effect was minimized in response to both diets. Serum NO or CRP did not change in response to either diet. In conclusion, LFWL diet improves microvascular reactivity compared to LFWM diet and increased vascular NO contribution to the improved microvascular dilation. These data suggest that weight reduction on low fat diet is critical for microvascular health.

Exercise and Vascular Insulin Sensitivity in the Skeletal Muscle and Brain

We present the hypothesis that exercise-induced hyperemia, perhaps through vascular shear stress, represents an important factor responsible for the effects of physical activity (PA) on vascular insulin sensitivity. Specifically, we postulate PA involving the greatest amount of skeletal muscle mass and the greatest central neural recruitment maximizes perfusion and consequently enhances vascular insulin sensitivity in the skeletal muscle and brain.

Endothelin-1/nitric oxide balance and HOMA index in children with excess weight and hypertension: a pathophysiological model of hypertension

The aim of this study was to investigate the relationship between endothelin-1, nitric oxide, insulin resistance, and blood pressure in young subjects with a high prevalence of excess weight and/or elevated blood pressure. In a cohort of 238 children (mean age = 11.1 years), height, weight, waist circumference, and blood pressure were assessed. Body mass index, waist-to-height ratio, and blood pressure percentiles were calculated, and the children were classified as having excess weight and elevated blood pressure according to the International Obesity Task Force and the US blood pressure nomograms specific for gender, age and height, respectively. Endothelin-1 and nitric oxide production were assessed, and the homeostatic model assessment index was calculated. Forty-three percent of children were male, 71% had excess weight, and 37% had systolic and/or diastolic values above the ninetieth percentile. Plasma endothelin-1 and nitric oxide production were independently correlated (p < 0.05). In multivariate analyses, the HOMA index was associated with systolic and diastolic blood pressure (p = 0.01), and nitric oxide was independently related to diastolic blood pressure (p = 0.04), even after adjustment for measures of body composition. By using the waist-to-height ratio instead of BMI in the statistical model, the association between the homeostatic model assessment index and blood pressure was attenuated, while the results remained similar for nitric oxide. No correlation was found between endothelin-1 and blood pressure. In our study population, the correlation between nitric oxide and blood pressure and the lack of a relationship between endothelin-1 and blood pressure could be explained by an increase in the vasodilator effect of local and systemic nitric oxide, which counteracts the possible hypertensive effect of endothelin-1.

Skeletal muscle Nur77 and NOR1 insulin responsiveness is blunted in obesity and type 2 diabetes but improved after exercise training

Obesity and type 2 diabetes (T2DM) are characterized by a blunted metabolic response to insulin, and strongly manifests in skeletal muscle insulin resistance. The orphan nuclear receptors, Nur77 and NOR1, regulate insulin-stimulated nutrient metabolism where Nur77 and NOR1 gene expression is increased with acute aerobic exercise and acute insulin stimulation. Whether Nur77 or NOR1 are associated with the insulin-sensitizing effects of chronic aerobic exercise training has yet to be elucidated. Fourteen lean healthy controls (LHC), 12 obese (OB), and 10 T2DM individuals (T2DM) underwent hyperinsulinemic-euglycemic clamps with skeletal muscle biopsies. Muscle was analyzed for Nur77 and NOR1 gene and protein expression at basal and insulin-stimulated conditions. Furthermore, a subcohort of 18 participants (OB, n = 12; T2DM, n = 6) underwent a 12-week aerobic exercise intervention (85% HRmax , 60 min/day, 5 days/week). In response to insulin infusion, LHC increased protein expression of Nur77 (8.7 ± 3.2-fold) and NOR1 (3.6 ± 1.1-fold), whereas OB and T2DM remained unaffected. Clamp-derived glucose disposal rates correlated with Nur77 (r2  = 0.14) and NOR1 (r2  = 0.12) protein expression responses to insulin, whereas age (Nur77: r2  = 0.22; NOR1: r2  = 0.25) and BMI (Nur77: r2  = 0.22; NOR1: r2  = 0.42) showed inverse correlations, corroborating preclinical data. In the intervention cohort, exercise improved Nur77 protein expression in response to insulin (PRE: -1.2 ± 0.3%, POST: 6.2 ± 1.5%). Also, insulin treatment of primary human skeletal muscle cells increased Nur77 and NOR1 protein. These findings highlight the multifactorial nature of insulin resistance in human obesity and T2DM. Understanding the regulation of Nur77 and NOR1 in skeletal muscle and other insulin-sensitive tissues will create opportunities to advance therapies for T2DM.

Exercise-induced hyperemia is associated with knee extensor fatigability in adults with type 2 diabetes

The aim of this study was to compare fatigability, contractile function, and blood flow to the knee extensor muscles after dynamic exercise in patients with type 2 diabetes mellitus (T2DM) and controls. The hypotheses were that patients with T2DM would demonstrate greater fatigability than controls, and greater fatigability would be associated with a lower exercise-induced increase in blood flow and greater impairments in contractile function. Patients with T2DM ( n = 15; 8 men; 62.4 ± 9.0 yr; 30.4 ± 7.7 kg/m²; 7,144 ± 3,294 steps/day) and 15 healthy control subjects (8 men, 58.4 ± 6.9 yr; 28.4 ± 4.6 kg/m²; 7,893 ± 2,323 steps/day) were matched for age, sex, body mass index, and physical activity. Fatigability was quantified as the reduction in knee extensor power during a 6-min dynamic exercise. Before and after exercise, vascular ultrasonography and electrical stimulation were used to assess skeletal muscle blood flow and contractile properties, respectively. Patients with T2DM had greater fatigability (30.0 ± 20.1% vs. 14.6 ± 19.0%, P < 0.001) and lower exercise-induced hyperemia (177 ± 90% vs. 194 ± 79%, P = 0.04) than controls but similar reductions in the electrically evoked twitch amplitude (37.6 ± 24.8% vs. 31.6 ± 30.1%, P = 0.98). Greater fatigability of the knee extensor muscles was associated with postexercise reductions in twitch amplitude ( r = 0.64, P = 0.001) and lesser exercise-induced hyperemia ( r = -0.56, P = 0.009). Patients with T2DM had greater lower-limb fatigability during dynamic exercise, which was associated with reduced contractile function and lower skeletal muscle blood flow. Thus, treatments focused on enhancing perfusion and reversing impairments in contractile function in patients with T2DM may offset lower-limb fatigability and aid in increasing exercise capacity. NEW & NOTEWORTHY Although prior studies compare patients with type 2 diabetes mellitus (T2DM) with lean controls, our study includes controls matched for age, body mass, and physical activity to more closely assess the effects of T2DM. Patients with T2DM demonstrated no impairment in macrovascular endothelial function, evidenced by similar flow-mediated dilation to controls. However, patients with T2DM had greater fatigability and reduced exercise-induced increase in blood flow (hyperemia) after a lower-limb dynamic fatiguing exercise compared with controls.

Dicarbonyl Stress and Glyoxalase-1 in Skeletal Muscle: Implications for Insulin Resistance and Type 2 Diabetes

Glyoxalase-1 (GLO1) is a ubiquitously expressed cytosolic protein which plays a role in the natural maintenance of cellular health and is abundantly expressed in human skeletal muscle. A consequence of reduced GLO1 protein expression is cellular dicarbonyl stress, which is elevated in obesity, insulin resistance and type 2 diabetes (T2DM). Both in vitro and pre-clinical models suggest dicarbonyl stress per se induces insulin resistance and is prevented by GLO1 overexpression, implicating a potential role for GLO1 therapy in insulin resistance and type 2 diabetes (T2DM). Recent work has identified the therapeutic potential of novel natural agents as a GLO1 inducer, which resulted in improved whole-body metabolism in obese adults. Given skeletal muscle is a major contributor to whole-body glucose, lipid, and protein metabolism, such GLO1 inducers may act, in part, through mechanisms in skeletal muscle. Currently, investigations examining the specificity of dicarbonyl stress and GLO1 biology in human skeletal muscle are lacking. Recent work from our lab indicates that dysregulation of GLO1 in skeletal muscle may underlie human insulin resistance and that exercise training may impart therapeutic benefits. This minireview will summarize the existing human literature examining skeletal muscle GLO1 and highlight the emerging therapeutic concepts for GLO1 gain-of-function in conditions such as insulin resistance and cardiometabolic disease.

Insulin resistance in an animal model of polycystic ovary disease is aggravated by vitamin D deficiency: Vascular consequences

Hyperandrogenic state in females is accompanied with metabolic syndrome, insulin resistance and vascular pathologies. A total of 67%-85% of hyperandrogenic women suffer also from vitamin D deficiency. We aimed to check a potential interplay between hyperandrogenism and vitamin D deficiency in producing insulin resistance and effects on coronary resistance arteries. Adolescent female rats were divided into four groups, 11-12 animals in each. Transdermal testosterone-treated and vehicle-treated animals were kept either on vitamin D-deficient or on vitamin D-supplemented diet for 8 weeks. Plasma sexual steroid, insulin, leptin and vitamin D plasma levels were measured, and oral glucose tolerance test was performed. In coronary arterioles, insulin receptor and vitamin D receptor expressions were tested by immunohistochemistry, and insulin-induced relaxation was measured in vitro on isolated coronary resistance artery segments. Testosterone impaired glucose tolerance, and it diminished insulin relaxation but did not affect the expression of insulin and vitamin D receptors in vascular tissue. Vitamin D deficiency elevated postprandial insulin levels and homeostatic model assessment insulin resistance. It also diminished insulin-induced coronary arteriole relaxation, while it raised the expression of vitamin D and insulin receptors in the endothelial and medial layers. Our conclusion is that both hyperandrogenism and vitamin D deficiency reduce sensitivity of coronary vascular tissue to insulin, but they do it with different mechanisms.

Longer diabetes duration reduces myocardial blood flow in remote myocardium assessed by dynamic myocardial CT perfusion

AIMS

To investigate the relationship of type 2 diabetes duration and myocardial blood flow (MBF) assessed by myocardial CT perfusion.

MATERIALS AND METHODS

We prospectively included 140 patients with type 2 diabetes who underwent dynamic myocardial CT perfusion exam. MBF of the remote myocardium was calculated using the deconvolution technique and the Voronoi method. The relationships of MBF and diabetic duration, diabetic complications, conventional risk factors, coronary calcium, and coronary stenosis were assessed by logistic regression analysis.

RESULTS

A weak but significantly negative relationship was present between diabetes duration and MBF (R² = 0.05, p < 0.01). The average MBF of patients with a duration of >8 years was 13% lower than that of the remaining patients (1.11 ± 0.35 vs 1.28 ± 0.27 ml min^-1 g^-1, p < 0.01). Duration of one year was associated with a 6% increased risk for low MBF (<1.18 ml min^-1 g^-1) (odds ratio 1.06, 95% confidence interval 1.01-1.12, p < 0.05). Calcium score was also a significant factor for low MBF (odds ratio 1.08 (per 100 Agatston units), 95% confidence interval 1.01-1.17, p < 0.05).

CONCLUSION

Longer diabetes duration is associated with lower MBF independent of conventional cardiac risk factors or the presence of coronary stenosis.

Reciprocal regulation of eNOS and caveolin-1 functions in endothelial cells

We hypothesized that the maintenance of vascular homeostasis is critically dependent on the expression and reciprocal regulation of caveolin-1 (Cav-1) and endothelial nitric oxide synthase (eNOS) in endothelial cells (ECs). Skeletal muscle biopsies from subjects with type 2 diabetes showed 50% less Cav-1 and eNOS than those from lean healthy controls. The Cav-1:eNOS expression ratio was 200:1 in primary culture human ECs. Cav-1 small interfering RNA (siRNA) reduced eNOS protein and gene expression in association with a twofold increase in eNOS phosphorylation and nitrate production per molecule of eNOS, which was reversed in cells overexpressing Adv-Cav-1-GFP. Upon addition of the Ca²⁺ ionophore A23187 to activate eNOS, we observed eNOS Ser1177 phosphorylation, its translocation to β-catenin-positive cell–cell junctions, and increased colocalization of eNOS and Cav-1 within 5 min. We also observed Cav-1 S-nitrosylation and destabilization of Cav-1 oligomers in cells treated with A23187 as well as insulin or albumin, and this could be blocked by L-NAME, PP2, or eNOS siRNA. Finally, caveola-mediated endocytosis of albumin or insulin was reduced by Cav-1 or eNOS siRNA, and the effect of Cav-1 siRNA was rescued by Adv-Cav-1-GFP. Thus, Cav-1 stabilizes eNOS expression and regulates its activity, whereas eNOS-derived NO promotes caveola-mediated endocytosis.

Regular Aerobic, Resistance, and Cross-Training Exercise Prevents Reduced Vascular Function Following a High Sugar or High Fat Mixed Meal in Young Healthy Adults

The postprandial state can negatively influence flow mediated dilation (FMD), a predictor of atherosclerosis and cardiovascular disease. This investigation was designed to determine the effect of regular aerobic and/or resistance exercise on postprandial FMD after a high sugar or high fat mixed meal. Forty-five healthy participants were recruited from one of four groups: lean sedentary (SED), runners, weight lifters, and cross-trainers. Participants were randomly crossed over to a high sugar meal (HSM) and a high fat mixed meal (HFMM; both fat and carbohydrate). Pre-and postprandial endothelial function was assessed for both meals using brachial artery FMD. Plasma lipids, insulin, glucose, hs-CRP, and SOD were also measured with both meals. Endothelium-independent dilation was determined via sublingual nitroglycerin. Brachial artery FMD was reduced in SED following the HSM (9.9 ± 0.9% at baseline, peak reduction at 60 min 6.5 ± 1.0%) and the HFMM (9.4 ± 0.9% at baseline, peak reduction at 120 min 5.9 ± 1.2%; P < 0.05 for both, Mean ± SEM). There was no change in FMD after either HSM or HFMM in runners, weight lifters, and cross-trainers. Post-prandial increases in blood glucose, insulin and triglycerides were less pronounced in the exercisers compared to SED. In addition, exercisers presented lower baseline plasma hs-CRP and higher SOD activity. Nitroglycerin responses were similar among groups. These results suggest that endothelial function is reduced in sedentary adults after a HSM or HFMM, but not in regular aerobic or resistance exercisers. This response may be due to favorable postprandial metabolic responses or lower postprandial levels of inflammation and oxidative stress. These findings may help to explain the cardioprotective effect of exercise.

Liver-specific rescuing of CEACAM1 reverses endothelial and cardiovascular abnormalities in male mice with null deletion of Ceacam1 gene

Objective

Mice with global null mutation of Ceacam1 (Cc1^−/−), display impairment of insulin clearance that causes hyperinsulinemia followed by insulin resistance, elevated hepatic de novo lipogenesis, and visceral obesity. In addition, they manifest abnormal vascular permeability and elevated blood pressure. Liver-specific rescuing of Ceacam1 reversed all of the metabolic abnormalities in Cc1^{−/−liver+} mice. The current study examined whether Cc1^−/− male mice develop endothelial and cardiac dysfunction and whether this relates to the metabolic abnormalities caused by defective insulin extraction.

Methods and results

Myography studies showed reduction of agonist-stimulated nitric oxide production in resistance arterioles in Cc1^−/−, but not Cc1^{−/−liver+} mice. Liver-based rescuing of CEACAM1 also attenuated the abnormal endothelial adhesiveness to circulating leukocytes in parallel to reducing plasma endothelin-1 and recovering plasma nitric oxide levels. Echocardiography studies revealed increased septal wall thickness, cardiac hypertrophy and reduced cardiac performance in Cc1^−/−, but not Cc1^{−/−xliver+} mice. Insulin signaling experiments indicated compromised IRS1/Akt/eNOS pathway leading to lower nitric oxide level, and activated Shc/MAPK pathway leading to more endothelin-1 production in the aortae and hearts of Cc1^−/−, but not Cc1^{−/−xliver+} mice. The increase in the ratio of endothelin-1 receptor A/B indicated an imbalance in the vasomotor activity of Cc1^−/− mice, which was normalized in Cc1^{−/−xliver+} mice.

Conclusions

The data underscore a critical role for impaired CEACAM1-dependent hepatic insulin clearance pathways and resulting hyperinsulinemia and lipid accumulation in aortae and heart in regulating the cardiovascular function.

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Mice with global deletion of Ceacam1 gene (Cc1^−/−) manifest endothelial dysfunction which is reversed by liver-specific rescuing of CEACAM1.

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Restoring CEACAM1 expression in the liver reversed cardiac hypertrophy and rescued cardiac performance.

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Hyperinsulinemia emerging from impaired insulin clearance regulates endothelial and cardiovascular functions.

Microvascular Vasodilator Plasticity After Acute Exercise

Endothelium-dependent vasodilation is reduced after acute exercise or after high intraluminal pressure in isolated arterioles from sedentary adults but not in arterioles from regular exercisers. The preserved vasodilation in arterioles from exercisers is hydrogen peroxide (H2O2) dependent, whereas resting dilation is nitric oxide (NO) dependent. We hypothesize chronic exercise elicits adaptations allowing for maintained vasodilation when NO bioavailability is reduced.

TRAF3IP2 mediates high glucose-induced endothelin-1 production as well as endothelin-1-induced inflammation in endothelial cells

Hyperglycemia-induced production of endothelin (ET)-1 is a hallmark of endothelial dysfunction in diabetes. Although the detrimental vascular effects of increased ET-1 are well known, the molecular mechanisms regulating endothelial synthesis of ET-1 in the setting of diabetes remain largely unidentified. Here, we show that adapter molecule TRAF3 interacting protein 2 (TRAF3IP2) mediates high glucose-induced ET-1 production in endothelial cells and ET-1-mediated endothelial cell inflammation. Specifically, we found that high glucose upregulated TRAF3IP2 in human aortic endothelial cells, which subsequently led to activation of JNK and IKKβ. shRNA-mediated silencing of TRAF3IP2, JNK1, or IKKβ abrogated high-glucose-induced ET-converting enzyme 1 expression and ET-1 production. Likewise, overexpression of TRAF3IP2, in the absence of high glucose, led to activation of JNK and IKKβ as well as increased ET-1 production. Furthermore, ET-1 transcriptionally upregulated TRAF3IP2, and this upregulation was prevented by pharmacological inhibition of ET-1 receptor B using BQ-788, or inhibition of NADPH oxidase-derived reactive oxygen species using gp91ds-tat and GKT137831. Notably, we found that knockdown of TRAF3IP2 abolished ET-1-induced proinflammatory and adhesion molecule (IL-1β, TNF-α, monocyte chemoattractant protein 1, ICAM-1, VCAM-1, and E-selectin) expression and monocyte adhesion to endothelial cells. Finally, we report that TRAF3IP2 is upregulated and colocalized with CD31, an endothelial marker, in the aorta of diabetic mice. Collectively, findings from the present study identify endothelial TRAF3IP2 as a potential new therapeutic target to suppress ET-1 production and associated vascular complications in diabetes. NEW & NOTEWORTHY This study provides the first evidence that the adapter molecule TRAF3 interacting protein 2 mediates high glucose-induced production of endothelin-1 by endothelial cells as well as endothelin-1-mediated endothelial cell inflammation. The findings presented herein suggest that TRAF3 interacting protein 2 may be an important therapeutic target in diabetic vasculopathy characterized by excess endothelin-1 production.

Circulating soluble RAGE isoforms are attenuated in obese, impaired-glucose-tolerant individuals and are associated with the development of type 2 diabetes

The soluble receptor for advanced glycation end products (sRAGE) may be protective against inflammation associated with obesity and type 2 diabetes (T2DM). The aim of this study was to determine the distribution of sRAGE isoforms and whether sRAGE isoforms are associated with risk of T2DM development in subjects spanning the glucose tolerance continuum. In this retrospective analysis, circulating total sRAGE and endogenous secretory RAGE (esRAGE) were quantified via ELISA, and cleaved RAGE (cRAGE) was calculated in 274 individuals stratified by glucose tolerance status (GTS) and obesity. Group differences were probed by ANOVA, and multivariate ordinal logistic regression was used to test the association between sRAGE isoform concentrations and the proportional odds of developing diabetes, vs. normal glucose tolerance (NGT) or impaired glucose tolerance (IGT). When stratified by GTS, total sRAGE, cRAGE, and esRAGE were all lower with IGT and T2DM, while the ratio of cRAGE to esRAGE (cRAGE:esRAGE) was only lower (P < 0.01) with T2DM compared with NGT. When stratified by GTS and obesity, cRAGE:esRAGE was higher with obesity and lower with IGT (P < 0.0001) compared with lean, NGT. In ordinal logistic regression models, greater total sRAGE (odds ratio, 0.91; P < 0.01) and cRAGE (odds ratio, 0.84; P < 0.01) were associated with lower proportional odds of developing T2DM. Reduced values of sRAGE isoforms observed with both obesity and IGT are independently associated with greater proportional odds of developing T2DM. The mechanisms by which each respective isoform contributes to obesity and insulin resistance may reveal novel treatment strategies for diabetes.