Cecilia Morgantini

Anti-Inflammatory and Antioxidant Properties of HDLs Are Impaired in Type 2 Diabetes

OBJECTIVE In mice, 4F, an apolipoprotein A-I mimetic peptide that restores HDL function, prevents diabetes-induced atherosclerosis. We sought to determine whether HDL function is impaired in type 2 diabetic (T2D) patients and whether 4F treatment improves HDL function in T2D patient plasma in vitro. RESEARCH DESIGN AND METHODS HDL anti-inflammatory function was determined in 93 T2D patients and 31 control subjects as the ability of test HDLs to inhibit LDL-induced monocyte chemotactic activity in human aortic endothelial cell monolayers. The HDL antioxidant properties were measured using a cell-free assay that uses dichlorofluorescein diacetate. Oxidized fatty acids in HDLs were measured by liquid chromatography–tandem mass spectrometry. In subgroups of patients and control subjects, the HDL inflammatory index was repeated after incubation with L-4F. RESULTS The HDL inflammatory index was 1.42 ± 0.29 in T2D patients and 0.70 ± 0.19 in control subjects (P < 0.001). The cell-free assay was impaired in T2D patients compared with control subjects (2.03 ± 1.35 vs. 1.60 ± 0.80, P < 0.05), and also HDL intrinsic oxidation (cell-free assay without LDL) was higher in T2D patients (1,708 ± 739 vs. 1,233 ± 601 relative fluorescence units, P < 0.001). All measured oxidized fatty acids were significantly higher in the HDLs of T2D patients. There was a significant correlation between the cell-free assay values and the content of oxidized fatty acids in HDL fractions. L-4F treatment restored the HDL inflammatory index in diabetic plasma samples (from 1.26 ± 0.17 to 0.71 ± 0.11, P < 0.001) and marginally affected it in healthy subjects (from 0.81 ± 0.16 to 0.66 ± 0.10, P < 0.05). CONCLUSIONS In patients with T2D, the content of oxidized fatty acids is increased and the anti-inflammatory and antioxidant activities of HDLs are impaired.

Apolipoprotein A-I Mimetic Peptides Prevent Atherosclerosis Development and Reduce Plaque Inflammation in a Murine Model of Diabetes

OBJECTIVE To determine the effect of the apolipoprotein A-I (ApoA-I) mimetic peptide, D-4F, on atherosclerosis development in a pre-existing diabetic condition. RESEARCH DESIGN AND METHODS We induced hyperglycemia in 6-week-old apoE−/− female mice using streptozotocin. Half of the diabetic apoE−/− mice received D-4F in drinking water. Ten weeks later, plasma lipids, glucose, insulin levels, atherosclerotic lesions, and lesion macrophage content were measured. RESULTS Diabetic apoE−/− mice developed ∼300% more lesion area, marked dyslipidemia, increased glucose levels, and reduced plasma insulin levels when compared with nondiabetic apoE−/− mice. Atherosclerotic lesions were significantly reduced in the D-4F–treated diabetic apoE−/− mice in whole aorta (1.11 ± 0.73 vs. 0.58 ± 0.44, percentage of whole aorta, P < 0.01) and in aortic roots (36,038 ± 18,467 μm2/section vs. 17,998 ± 12,491 μm2/section, P < 0.01) when compared with diabetic apoE−/− mice that did not receive D-4F. Macrophage content in atherosclerotic lesions from D-4F–treated diabetic apoE−/− mice was significantly reduced when compared with nontreated animals (78.03 ± 26.1 vs. 29.6 ± 15.2 P < 0.001, percentage of whole plaque). There were no differences in glucose, insulin, total cholesterol, HDL cholesterol, and triglyceride levels between the two groups. Arachidonic acid, PGE2, PGD2, 15-HETE, 12-HETE, and 13-HODE concentrations were significantly increased in the liver tissue of diabetic apoE−/− mice compared with nondiabetic apoE−/− mice and significantly reduced by D-4F treatment. CONCLUSIONS Our results suggest that oral D-4F can prevent atherosclerosis development in pre-existing diabetic mice and this is associated with a reduction in hepatic arachidonic acid and oxidized fatty acid levels.

HDL lipid composition is profoundly altered in patients with type 2 diabetes and atherosclerotic vascular disease.

BACKGROUND AND AIMS We have previously shown that the anti-inflammatory and anti-oxidant functions of HDL are impaired in T2D patients. In this study, we examined whether HDL from T2D patients contains elevated levels of oxidized fatty acids and whether those levels correlate with cardiovascular disease (CVD). METHODS AND RESULTS HETEs and HODEs on HDL were determined by LC-MS/MS in 40 non-diabetic controls (ND), 40 T2D without CVD (D⁺CVD⁻) and 38 T2D with known history of CVD (D⁺CVD⁺). HDL oxidant index was evaluated by a cell-free assay using dichlorofluorescein. Twenty-six randomly selected subjects from the three groups underwent coronary calcium score evaluation (CAC). Major cardiovascular risk factors were similar among the groups. HETEs and HODEs content were significantly increased in HDL from D⁺CVD⁺ when compared to D⁺CVD⁻ and ND patients. HDL oxidant index was not different among the three groups; however, it was significantly higher in patients with CAC score >100 when compared to patients with CAC score <100. CONCLUSION Patients with D⁺CVD⁻ and D⁺CVD⁺ are characterized by a severe, graded enrichment of oxidized fatty acids on HDL. In the present study, a loss of HDL function (as estimated by the HDL oxidant index) is observed only in patients with more advanced atherosclerosis.

Effect of mild hyperisulinemia on conduit vessel endothelial function: role of noradrenergic activation.

Objective: The evidence that an exogenously induced modest hyperinsulinemia deteriorates conductance artery endothelial function – flow-mediated dilatation (FMD) – in healthy individuals is in contrast with in-vitro and in-vivo studies that consistently found that insulin facilitates both nitric oxide release and the endothelium-dependent dilatation. The aim of this study was to verify whether this effect is caused by the enhancement of insulin-induced adrenergic tone. Method: In 10 healthy male volunteers, endothelium-dependent (FMD) and endothelium-independent (glyceryl trinitrate, GTN) dilatation were evaluated by high-resolution ultrasound of the brachial artery, combined with a computerized edge detection system, at baseline (−60 and 0 min) and after 120 and 240 min during insulin infusion (INS study). In five participants, randomly selected from the initial group, the study was repeated during an isotonic saline (0.9% sodium chloride) intravenous infusion (SAL study). In an additional five participants, insulin infusion was preceded by an intravenous infusion of clonidine started 40 min before insulin and continued throughout the study (INS + CLN study). Results: Plasma norepinephrine concentration increased in the INS study from 260 ± 40 to 333 ± 62 pg/ml (P < 0.05), whereas it remained stable throughout the INS + CLN study. In the INS study, no change in FMD was observed, whereas the response to GTN tended to decrease (P = 0.09). In the INS + CLN study, no significant changes in FMD response were observed, whereas GTN response was completely restored. Conclusion: Physiological hyperinsulinemia has no effect on endothelium-dependent vasodilatation in conduit vessels of healthy individuals, but it induces a slight decline in endothelium-independent vasodilatation, which is entirely explained by the insulin-induced noradrenergic activation.

Effects of GIK (glucose-insulin-potassium) on stress-induced myocardial ischaemia.

Despite the evidence in experimental animal models that insulin, or GIK (glucose-insulin-potassium), improves left ventricular function and perfusion during both acute and chronic ischaemia, clinical studies have generated conflicting results. We tested the hypothesis that pretreatment with GIK attenuates the vascular and functional effects of stress-induced myocardial ischaemia in humans. Twenty-two patients with evidence of inducible myocardial ischaemia were enrolled; 11 patients with normal ventricular function underwent two dipyridamole echocardiography tests, and 11 with regional contractility defects from previous myocardial infarction were submitted to two ECG exercise tests combined with 201Tl myocardial perfusion scintigraphy; the tests were preceded by 60 min of either normal saline or an isoglycaemic GIK infusion. On a stress echocardiogram, a 30% reduction in the severity of ischaemia was observed. On ECG ergometry, GIK infusion slightly increased the time to ischaemia (+0.6 min, P=0.07); however, the higher workload (+8%, P=0.07) was achieved at a similar rate-pressure plateau. On scintigraphy, an increase in ischaemic segments (+48%, P<0.001) was imaged mainly at the expense of viable (but non-ischaemic) and non-viable segments, which were reduced by 60%. GIK affected stress-induced left ventricular underperfusion only marginally (GIK: 39.7+/-2.5 compared with saline: 35.4+/-2.2 units, P<0.05), but significantly improved its acute reversibility (-42+/-4 compared with -25+/-4%, P<0.001). We conclude that GIK pretreatment attenuates the effect of ischaemia on myocardial contractility, slightly improves exercise tolerance and causes a more rapid and diffuse recovery of post-ischaemic reperfusion.

Reducing cholesterol and fat intake improves glucose tolerance by enhancing beta cell function in non-diabetic subjects.

Context A diet low in cholesterol and fat is commonly recommended to prevent metabolic and cardiovascular diseases; however, its effect on glucose tolerance is largely unknown. Objective We examined whether and by which mechanisms a chronic reduction of cholesterol and fat intake affects glucose tolerance in nondiabetic individuals, independently of weight changes. Design and Participants In this crossover, randomized clinical trial, 30 healthy subjects, including 15 with family history of type 2 diabetes (T2D) (T2D offspring), underwent a 75-g oral glucose tolerance test (OGTT) after two 14-day isocaloric high-cholesterol, high-fat (HChF) or low-cholesterol, and low-fat (LChF) diets. Main Outcome Measures We evaluated changes in glucose tolerance, β cell function, insulin clearance, and insulin sensitivity by modeling plasma glucose, insulin, and C-peptide levels during the OGTT. Results The shift from the HChF to the LChF diet was neutral on body weight but increased glucose tolerance (mean glucose -5%, P = 0.01) and three components of β cell function: glucose sensitivity (+17%, P = 0.01), insulin secretion at fasting glucose (+20%, P = 0.02), and potentiation (+19%, P = 0.03). The LChF diet improved insulin sensitivity (+7%, P = 0.048) only in T2D offspring, who tended to be more susceptible to the positive effect of the diet on glucose tolerance. Conclusions A chronic and isocaloric decrease in dietary cholesterol and fat intake improves glucose tolerance by diffusely ameliorating β cell function in nondiabetic subjects. Individuals genetically predisposed to develop T2D tend to be more susceptible to the positive effect of this dietary intervention on glucose tolerance and insulin sensitivity.