Breakfast partly restores the anti-inflammatory function of high-density lipoproteins from patients with type 2 diabetes mellitus.

Background and aims: High-density lipoproteins (HDL) of patients with type 2 diabetes mellitus (T2DM) have impaired anti-inflammatory activities. The anti-inflammatory activity of HDL has been determined ex vivo after isolation by different methods from blood mostly obtained after overnight fasting. We first determined the effect of the HDL isolation method, and subsequently the effect of food intake on the anti-inflammatory function of HDL from T2DM patients. Methods: Blood was collected from healthy controls and T2DM patients after an overnight fast, and from T2DM patients 3 h after breakfast (n = 17 each). HDL was isolated by a two-step density gradient ultracentrifugation in iodixanol (HDLDGUC2), by sequential salt density flotation (HDLSEQ) or by PEG precipitation (HDLPEG). The anti-inflammatory function of HDL was determined by the reduction of the TNFα-induced expression of VCAM-1 in human coronary artery endothelial cells (HCAEC) and retinal endothelial cells (REC). Results: HDL isolated by the three different methods from healthy controls inhibited TNFα-induced VCAM-1 expression in HCAEC. With apoA-I at 0.7 µM, HDLDGUC2 and HDLSEQ were similarly effective (16% versus 14% reduction; n = 3; p > 0.05) but less effective than HDLPEG (28%, p < 0.05). Since ultracentrifugation removes most of the unbound plasma proteins, we used HDLDGUC2 for further experiments. With apoA-I at 3.2 µM, HDL from fasting healthy controls and T2DM patients reduced TNFα-induced VCAM-1 expression in HCAEC by 58 ± 13% and 51 ± 20%, respectively (p = 0.35), and in REC by 42 ± 13% and 25 ± 18%, respectively (p < 0.05). Compared to preprandial HDL, postprandial HDL from T2DM patients reduced VCAM-1 expression by 56 ± 16% (paired test: p < 0.001) in HCAEC and by 34 ± 13% (paired test: p < 0.05) in REC. Conclusions: The ex vivo anti-inflammatory activity of HDL is affected by the HDL isolation method. Two-step ultracentrifugation in an iodixanol gradient is a suitable method for HDL isolation when testing HDL anti-inflammatory function. The anti-inflammatory activity of HDL from overnight fasted T2DM patients is significantly impaired in REC but not in HCAEC. The anti-inflammatory function of HDL is partly restored by food intake.

Role of plasma adiponectin on the HDL-cholesterol raising effect of atorvastatin in patients with type 2 diabetes.

OBJECTIVE: Adiponectin, secreted by adipose tissue, plays an important role in lipoprotein metabolism and also affects carbohydrate and insulin pathways. We studied the effects of atorvastatin treatment on plasma adiponectin and high density cholesterol (HDL) levels in patients with type 2 diabetes. RESEARCH DESIGN AND METHODS: In the 'Diabetes Atorvastatin Lipid Intervention' (DALI) study, a randomized placebo-controlled study on the effects of atorvastatin treatment in 194 patients with type 2 diabetes and mildly elevated plasma triglycerides, adiponectin levels, lipoproteins, cholesteryl ester transfer protein (CETP) mass, as well as postheparin lipoprotein lipase (LPL) and hepatic lipase (HL) activities were assessed at baseline and after 6 months of treatment (placebo, 10 mg or 80 mg atorvastatin). RESULTS: At baseline, plasma adiponectin levels were positively associated with HDL cholesterol (r = 0.40, p < 0.001), and apoA-I (r = 0.38, p < 0.001) in both males and females. Adiponectin was negatively associated with triglycerides (r = -0.26, p < 0.001) in males as well as in females. Atorvastatin treatment had no effect on plasma adiponectin levels. However, adiponectin levels at baseline significantly predicted the effect of atorvastatin treatment on HDL-cholesterol (p = 0.007), i.e. patients with the highest baseline plasma adiponectin concentration (tertile 3) displayed the largest increase in plasma HDL cholesterol during treatment (8-10%), while the HDL-cholesterol increase in tertile 1 was almost negligible (1-3%). CONCLUSION: In this study, high baseline plasma adiponectin levels significantly affect the HDL-cholesterol response to atorvastatin treatment in patients with type 2 diabetes and therefore may play a role in defining future treatment strategy.

Reduced leucocyte cholesteryl ester transfer protein expression in acute coronary syndromes.

OBJECTIVE: Cholesterol ester transfer protein (CETP) plays an important role in HDL cholesterol metabolism. Leucocytes, including monocyte-derived macrophages in the arterial wall synthesize and secrete CETP, but its role in atherosclerosis is unclear. The aim of the current study was to investigate the effect of acute coronary syndromes (ACS) on leucocyte CETP expression. RESEARCH DESIGN: Peripheral blood mononuclear cells (PBMCs) were freshly isolated from hospitalized ACS patients displaying Braunwald class IIIB unstable angina pectoris (UAP) on admission (t = 0) and at 180 days post inclusion (t = 180) for analysis of CETP expression. In addition, to prove the potential correlation between leucocyte CETP and ACS the effect of acute myocardial infarction on leucocyte CETP expression was studied in CETP transgenic mice. RESULTS: Upon admission, UAP patients displayed approximately 3-6 fold (P < 0.01) lower CETP mRNA and nearly absent CETP protein expression in PBMCs, as compared to healthy age-/sex-matched controls. Interestingly, CETP mRNA and protein levels were significantly elevated in PBMCs isolated from UAP patients (both stabilized and refractory) at t = 180 as compared to t = 0 (P < 0.01), which was correlated with a reduced inflammatory status after medical treatment. In agreement with the data obtained in UAP patients, markedly down-regulated leucocyte CETP mRNA expression was observed after coronary artery ligation in CETP transgenic mice, which also correlated with increased serum amyloid A levels. CONCLUSIONS: We are the first to report that episodes of UAP in humans and myocardial infarction in CETP transgenic mice are associated with reduced leucocyte CETP expression. We propose that the impairment in leucocyte CETP production is associated with an enhanced inflammatory status, which could be clinically relevant for the pathogenesis of ACS.

Appraisal of hepatic lipase and lipoprotein lipase activities in mice.

A variety of methods are currently used to analyze HL and LPL activities in mice. In search of a simple methodology, we analyzed mouse preheparin and postheparin plasma LPL and HL activities using specific polyclonal antibodies raised in rabbit against rat HL (anti-HL) and in goat against rat LPL (anti-LPL). As an alternative, we analyzed HL activity in the presence of 1 M NaCl, a condition known to inhibit LPL activity in humans. The assays were validated using plasma samples from wild-type and HL-deficient C57BL/6 mice. We now show that the use of 1 M NaCl for the inhibition of plasma LPL activity in mice may generate incorrect measurements of both LPL and HL activities. Our data indicate that HL can be measured directly, without heparin injection, in preheparin plasma, because virtually all HL is present in an unbound form circulating in plasma. In contrast, measurable LPL activity is present only in postheparin plasma. Both HL and LPL can be measured using the same assay conditions (low salt and the presence of apolipoprotein C-II as an LPL activator). Total lipase activity in postheparin plasma minus preheparin HL activity reflects LPL activity. Specific antibodies are not required.

Plasma apolipoprotein A5 and triglycerides in type 2 diabetes.

AIMS/HYPOTHESIS: Variation in the human apolipoprotein (APO) A5 gene (APOA5) is associated with elevated plasma triglycerides. However, data on the exact role of plasma concentrations of APOA5 in human triglyceride homeostasis are lacking. In the present study, we estimated plasma APOA5 levels in patients with type 2 diabetes at baseline and during atorvastatin treatment, a lipid-lowering treatment that results in a reduction in plasma triglycerides and APOC3. SUBJECTS, MATERIALS AND METHODS: Plasma APOA5 concentration was measured by ELISA in 215 subjects with type 2 diabetes, who were taken from the Diabetes Atorvastatin Lipid-lowering Intervention (DALI) study, a 30-week randomised, double-blind, placebo-controlled study, and given atorvastatin 10 mg or 80 mg daily. RESULTS: At baseline, average plasma APOA5 concentration was 25.7+/-15.6 mug/100 ml. Plasma APOA5 (R (s)=0.40), APOC3 (R (s)=0.72) and APOE (R (s)=0.45) were positively correlated with plasma triglyceride levels (all p<0.001). In multiple linear regression analysis, adjusted for age and sex, the variation in plasma triglycerides was explained mostly by APOC3 (52%) and only to a small extent by APOA5 (6%) and APOE (1%). Atorvastatin treatment decreased plasma triglycerides, APOA5, APOC3 and APOE (all p<0.0001). After treatment, APOC3 remained the major determinant of plasma triglyceride levels (59%), while the contributions of APOA5 and APOE were insignificant (2 and 3%). CONCLUSIONS/INTERPRETATION: Our findings reveal a positive association between plasma APOA5 and triglycerides in patients with type 2 diabetes. Treatment with atorvastatin decreased plasma APOA5, APOC3, APOE and triglycerides. In contrast to APOC3, APOA5 is not a major determinant of triglyceride metabolism in these patients.