Paul J.W.H. Kappelle

Apolipoprotein B/A-I and total cholesterol/high-density lipoprotein cholesterol ratios both predict cardiovascular events in the general population independently of nonlipid risk factors, albuminuria and C-reactive protein

Kappelle PJWH, Gansevoort RT, Hillege JL, Wolffenbuttel BHR, Dullaart RPF on behalf of the PREVEND study group (University Medical Center Groningen and University of Groningen, Groningen, The Netherlands). Apolipoprotein B/A‐I and total cholesterol/high‐density lipoprotein cholesterol ratios both predict cardiovascular events in the general population independently of nonlipid risk factors, albuminuria and C‐reactive protein. J Intern Med 2011; 269: 232–242.

Increased LCAT activity and hyperglycaemia decrease the antioxidative functionality of HDL

Eur J Clin Invest 2012; 42 (5): 487–495

The plasma leptin/adiponectin ratio predicts first cardiovascular event in men: A prospective nested case-control study

OBJECTIVE The plasma leptin/adiponectin (L/A) ratio has been proposed as a preferential marker of atherosclerosis susceptibility compared to leptin and adiponectin alone. We determined the extent to which the L/A ratio predicts incident cardiovascular disease (CVD) taking account of clinical risk factors, microalbuminuria, the total cholesterol/HDL cholesterol (TC/HDL-C ratio), triglycerides, high sensitive C-reactive protein (hs-CRP) and insulin sensitivity (homeostasis model assessment (HOMA(ir))). METHODS A community-based prospective nested case-control study was carried out in 103 non-diabetic men who developed a first cardiovascular event (cases) and 106 male control subjects (no clinically manifest CVD and no lipid lowering drug use at baseline; median follow-up of 3.0 and 10.5 years, respectively). Plasma leptin, adiponectin, the leptin/adipnectin (L/A) ratio, as well as hs-CRP, HOMA(ir) and the TC/HDL-C ratio were determined at baseline. RESULTS Plasma leptin levels and the L/A ratio were higher in cases vs. controls (p=0.002 for both), but the difference in adiponectin was not significant (p=0.10). Age-adjusted incident CVD was associated with plasma leptin, adiponectin and the L/A ratio (p=0.045 to p=0.001). The relationships of incident CVD with plasma leptin (p=0.19) and adiponectin (p=0.073) lost statistical significance after additional adjustment for smoking, waist circumference, hypertension, microalbuminuria, the TC/HDL-C ratio, hs-CRP and HOMA(ir). In this fully adjusted analysis, the L/A ratio remained predictive of incident CVD (hazard ratio: 1.40 (95% CI 1.05-1.87), p=0.024). CONCLUSION This study suggests that the L/A ratio may be a preferential marker of a first cardiovascular event in men compared to plasma leptin and adiponectin levels alone.

Cholesteryl ester transfer protein inhibition in cardiovascular risk management: ongoing trials will end the confusion.

As delineated in this review, cholesteryl ester transfer protein (CETP) contributes to an atherogenic lipoprotein profile by redistributing cholesteryl esters from high density lipoprotein (HDL) toward apolipoprotein B-containing lipoproteins, especially when the concentration of acceptor triglyceride-rich lipoproteins is elevated. However, this lipid transfer protein may have antiatherogenic proprerties as well. Experimental evidence is accumulating which suggests that the atheroprotective reverse cholesterol transport pathway, whereby cholesterol is removed from peripheral macrophages to the liver for metabolism and biliary excretion, is stimulated by CETP in vivo. CETP could also play a role in host defense against infection and inflammatory processes. Moreover, recently published observational studies show that higher CETP levels may confer cardiovascular protection, whereas reported associations of cardiovascular disease (CVD) with CETP gene variations are equivocal. The concept that HDL cholesterol raising through inhibition of CETP may ameliorate CVD risk has been challenged by the failure of the CETP inhibitor, torcetrapib. Adverse clinical outcome associated with the use of this CETP inhibitor has been attributed to off-target effects, which relate to stimulation of aldosterone. Other CETP inhibitors, such as dalcetrapib and anacetrapib, are unlikely to increase blood pressure. Dalcetrapib is less potent than anacetrapib, which doubles HDL cholesterol. Both inhibitors considerably lower LDL cholesterol.Serious concerns remain about the validity of the concept that HDL cholesterol raising by means of CETP inhibition is a viable strategy. Results of ongoing clinical trials with these drugs will have to be awaited before making up the balance between possible benefits and harms related to pharmacological CETP inhibition.

High plasma cholesteryl ester transfer but not CETP mass predicts incident cardiovascular disease: a nested case-control study.

OBJECTIVE The relationship of cardiovascular disease (CVD) with plasma cholesteryl ester transfer protein (CETP) levels is controversial. We determined whether plasma cholesteryl ester transfer (CET), reflecting CETP-mediated transfer of cholesteryl esters from endogenous HDL towards apolipoprotein B-lipoproteins, predicts incident CVD. METHODS A prospective nested case-control study was carried out in 114 men who developed CVD and 105 controls. Participants did not use lipid lowering drugs at baseline. Plasma CET was assayed using an isotope method. RESULTS Plasma CET was 19% higher (P=0.030), whereas CETP mass was unaltered (P=0.30) in cases vs. controls. Plasma CET predicted CVD (age-adjusted hazard ratio (HR): 1.20 (95% CI 1.02-1.46, P=0.028), but incident CVD was unrelated to CETP mass (HR: 0.88 (95% CI 0.73-1.07), P=0.20). Plasma CET still predicted CVD after additional adjustment for total cholesterol/HDL cholesterol, triglycerides and non-lipid risk markers (HR: 1.22 (95% CI 1.02-1.46, P=0.031). CONCLUSION Plasma CET rather than CETP mass may be a determinant of cardiovascular risk.

Lower Serum Paraoxonase-1 Activity Is Related to Higher Serum Amyloid A Levels in Metabolic Syndrome

BACKGROUND AND AIMS High-density lipoproteins (HDL) contain the anti-oxidative enzyme, paraoxonase-1 (PON-1), which is important for atheroprotection. The acute phase reactant, serum amyloid A (SAA), an HDL-associated apolipoprotein, may impair PON-1 activity, whereas SAA and PON-1 are reciprocally regulated in response to acute inflammatory stimuli. The relationship of serum PON-1 activity with SAA during low-grade chronic inflammation is unclear. Here we tested the extent to which low serum PON-1 activity is related to high SAA levels in subjects with and without metabolic syndrome (MetS). METHODS In 19 nondiabetic subjects with MetS and 67 subjects without MetS, serum PON-1, assayed as its arylesterase activity, and SAA were measured together with plasma lipids and lipoproteins, high-sensitive C-reactive protein (hs-CRP) and insulin resistance (homeostasis model assessment (HOMA(ir)). RESULTS PON-1 activity was decreased (p=0.023), whereas SAA levels were increased (p=0.042) in MetS subjects, coinciding with higher hs-CRP levels and HOMA(ir) values. Multiple linear regression analysis revealed that age- and gender-adjusted PON-1 activity was related inversely to SAA (β=-0.256, p=0.020) after adjustment for MetS, or alternatively for hs-CRP and HOMA(ir) (β=-0.271, p=0.049). CONCLUSIONS Decreased serum PON-1 activity in MetS may in part be attributable to higher SAA levels. We suggest that higher SAA levels contribute to impaired HDL anti-oxidative function in MetS via an effect on PON-1 regulation.

Plasma proprotein convertase subtilisin–kexin type 9 does not change during 24 h insulin infusion in healthy subjects and type 2 diabetic patients

PURPOSE Proprotein convertase subtilisin-kexin type 9 (PCSK9) promotes low density lipoprotein (LDL) receptor degradation, thereby providing a key pathway for LDL metabolism. PCSK9 mRNA expression may be upregulated by insulin in murine models. Here we examined effects of exogenous hyperinsulinemia on plasma PCSK9 levels in humans without and with type 2 diabetes mellitus. METHODS A 24h moderately hyperinsulinemic glucose clamp (30 mU/kg/h) was performed in 8 healthy men and 8 male type 2 diabetic patients. Plasma PCSK9 was measured using a sandwich enzyme-linked immunosorbent assay. RESULTS Plasma LDL cholesterol and apolipoprotein B were lowered by insulin in healthy subjects and diabetic patients (P < 0.01 for all), whereas triglycerides were also decreased in healthy subjects (P < 0.01). Plasma PCSK9 levels remained unchanged in healthy subjects (median (interquartile range) change, -23 (-63 to 25) %, P = 0.50) and in diabetic patients (change, 4 (-17 to 44) %, P = 0.20). Individual absolute and relative changes in LDL cholesterol, apolipoprotein B and triglycerides after 24h of insulin were unrelated to changes in PCSK9 (P > 0.15 for all). CONCLUSION Plasma PCSK9 levels are not increased by exposure to moderate 24h hyperinsulinemia in healthy and type 2 diabetic individuals.

Plasma lecithin:cholesterol acyltransferase activity modifies the inverse relationship of C-reactive protein with HDL cholesterol in nondiabetic men

Lecithin:cholesterol acyltransferase (LCAT) is instrumental in high-density lipoprotein (HDL) maturation, but high LCAT levels do not predict low cardiovascular risk. LCAT may affect antioxidative or anti-inflammatory properties of HDL. We determined the relationship of plasma high-sensitivity C-reactive protein (CRP) with LCAT activity and evaluated whether LCAT activity modifies the decreasing effect of HDL cholesterol (HDL-C) on CRP, as an estimate of its anti-inflammatory properties. Plasma HDL-C, apolipoprotein (apo) A-I and LCAT activity (exogenous substrate method) were measured in 260 nondiabetic men without cardiovascular disease. CRP was correlated inversely with HDL-C and apo A-I, and positively with LCAT activity (P<0.01 to 0.001). Multivariate regression analysis demonstrated that age- and smoking-adjusted plasma CRP levels were associated negatively with HDL-C (beta=-0.224, P<0.001) and positively with LCAT activity (beta=0.119, P=0.034), as well as with the interaction between HDL-C and LCAT activity (beta=0.123, P=0.026). There was also an interaction between apo A-I and LCAT activity on CRP (beta=0.159, P=0.005). These relationships remained similar after adjustment for apo B-containing lipoproteins. In conclusion, the inverse relationship of HDL-C with CRP is attenuated by LCAT activity at higher HDL-C levels. It is hypothesized that LCAT could mitigate HDLs anti-inflammatory or antioxidative properties at higher HDL-C concentrations.

Atorvastatin treatment lowers fasting remnant-like particle cholesterol and LDL subfraction cholesterol without affecting LDL size in type 2 diabetes mellitus: Relevance for non-HDL cholesterol and apolipoprotein B guideline targets.

The extent to which atorvastatin treatment affects LDL size, LDL subfraction levels and remnant-like particle cholesterol (RLP-C) was determined in type 2 diabetes. We also compared LDL size and RLP-C in relation to guideline cut-off values for LDL cholesterol, non-HDL cholesterol and apolipoprotein (apo) B. Changes in LDL size and RLP-C were determined in fasting plasma from type 2 diabetic patients after 30 weeks administration of atorvastatin (10 mg daily, n=65; 80 mg daily, n=62) or placebo (n=58). LDL subfraction cholesterol was measured in 74 participants. Atorvastatin lowered LDL cholesterol, non-HDL cholesterol, triglycerides, apo B and RLP-C (P<0.001 for all at each dose) and LDL mean peak particle diameter remained unchanged. Atorvastatin treatment decreased cholesterol concentrations in all LDL subfractions (P<0.001 for each dose). RLP-C at follow-up was lower in those patients achieving the non-HDL cholesterol or the apo B guideline targets (P<0.01), but the LDL cholesterol cut-off value failed to discriminate. In conclusion, atorvastatin lowers fasting RLP-C and LDL subfraction cholesterol in diabetes. The proposed guideline cut-off levels for non-HDL cholesterol and apo B may be superior to the LDL cholesterol target in discriminating between higher and lower RLP-C levels.

Plasma phospholipid transfer protein activity is independently determined by obesity and insulin resistance in non-diabetic subjects

BACKGROUND Phospholipid transfer protein (PLTP) is an emerging cardio-metabolic risk factor which is intricately involved in lipoprotein metabolism. Elevated plasma PLTP activity levels are reported in obesity and diabetes mellitus, but the relative contributions of obesity and insulin resistance to plasma PLTP activity remain unclear. We tested whether plasma PLTP activity is independently related to (central) obesity and insulin resistance in non-diabetic subjects. METHODS The relationships of plasma PLTP activity levels (phospholipid vesicles-HDL system) with waist circumference, waist/hip ratio, body mass index (BMI) and insulin resistance (homeostasis model assessment (HOMA(ir))) were determined in 313 non-diabetic subjects (273 men). RESULTS PLTP activity was higher in 67 subjects with enlarged waist circumference (NCEP-ATP-III criteria; 102 ± 11 AU) compared to 246 subjects with normal waist (98 ± 11 AU, P=0.027). In univariate analysis PLTP activity correlated positively with waist (r=0.188), waist/hip ratio (r=0.143), BMI (r=0.125) and HOMA(ir) (r=0.192) (P<0.05 to P<0.001). The relationship of PLTP with HOMA(ir) was confined to subjects with the highest waist circumference and waist/hip ratio. In age- and sex-adjusted multiple linear regression models, waist circumference (β=0.158, P=0.025), but not BMI, predicted PLTP activity independently of HOMA(ir) (β=0.126, P=0.047). Furthermore, both waist and waist/hip ratio interacted positively with HOMA(ir) on PLTP activity (β=0.109, P=0.056 and β=0.156, P=0.034, respectively). CONCLUSIONS In non-diabetic subjects, both obesity and insulin resistance influence plasma PLTP activity, resulting in elevated plasma PLTP activity particularly with combined increases in obesity and insulin resistance. Higher PLTP activity could contribute to elevated cardiovascular risk in the presence of obesity and insulin resistance.