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Cholesteryl ester transfer protein (CETP) mediates the transfer of HDL cholesteryl esters for triglyceride (TG) in VLDL/LDL. CETP inhibition, with anacetrapib, increases HDL-cholesterol, reduces LDL-cholesterol, and lowers TG levels. This study describes the mechanisms responsible for TG lowering by examining the kinetics of VLDL-TG, apoC-II, apoC-III, and apoE. Mildly hypercholesterolemic subjects were randomized to either placebo (N = 10) or atorvastatin 20 mg/qd (N = 29) for 4 weeks (period 1) followed by 8 weeks of anacetrapib, 100 mg/qd (period 2). Following each period, subjects underwent stable isotope metabolic studies to determine the fractional catabolic rates (FCRs) and production rates (PRs) of VLDL-TG and plasma apoC-II, apoC-III, and apoE. Anacetrapib reduced the VLDL-TG pool on a statin background due to an increased VLDL-TG FCR (29%; P = 0.002). Despite an increased VLDL-TG FCR following anacetrapib monotherapy (41%; P = 0.11), the VLDL-TG pool was unchanged due to an increase in the VLDL-TG PR (39%; P = 0.014). apoC-II, apoC-III, and apoE pool sizes increased following anacetrapib; however, the mechanisms responsible for these changes differed by treatment group. Anacetrapib increased the VLDL-TG FCR by enhancing the lipolytic potential of VLDL, which lowered the VLDL-TG pool on atorvastatin background. There was no change in the VLDL-TG pool in subjects treated with anacetrapib monotherapy due to an accompanying increase in the VLDL-TG PR., (Copyright © 2017 by the American Society for Biochemistry and Molecular Biology, Inc.)

Background: Individuals treated with the cholesteryl ester transfer protein (CETP) inhibitor anacetrapib exhibit a reduction in both LDL cholesterol and apolipoprotein B (ApoB) in response to monotherapy or combination therapy with a statin. It is not clear how anacetrapib exerts these effects; therefore, the goal of this study was to determine the kinetic mechanism responsible for the reduction in LDL and ApoB in response to anacetrapib., Methods: We performed a trial of the effects of anacetrapib on ApoB kinetics. Mildly hypercholesterolemic subjects were randomized to background treatment of either placebo (n = 10) or 20 mg atorvastatin (ATV) (n = 29) for 4 weeks. All subjects then added 100 mg anacetrapib to background treatment for 8 weeks. Following each study period, subjects underwent a metabolic study to determine the LDL-ApoB-100 and proprotein convertase subtilisin/kexin type 9 (PCSK9) production rate (PR) and fractional catabolic rate (FCR)., Results: Anacetrapib markedly reduced the LDL-ApoB-100 pool size (PS) in both the placebo and ATV groups. These changes in PS resulted from substantial increases in LDL-ApoB-100 FCRs in both groups. Anacetrapib had no effect on LDL-ApoB-100 PRs in either treatment group. Moreover, there were no changes in the PCSK9 PS, FCR, or PR in either group. Anacetrapib treatment was associated with considerable increases in the LDL triglyceride/cholesterol ratio and LDL size by NMR., Conclusion: These data indicate that anacetrapib, given alone or in combination with a statin, reduces LDL-ApoB-100 levels by increasing the rate of ApoB-100 fractional clearance., Trial Registration: ClinicalTrials.gov NCT00990808., Funding: Merck & Co. Inc., Kenilworth, New Jersey, USA. Additional support for instrumentation was obtained from the National Center for Advancing Translational Sciences (UL1TR000003 and UL1TR000040).

Purpose: Celiac disease is associated with hypocholesterolemia, which is thought to contribute to a favorable cardiovascular risk profile. This led to suggestions that the diagnosis of celiac disease and its treatment with a gluten-free diet may result in elevation of the serum cholesterol level and worsen this risk profile. However, no study proves this in adults. We therefore examined the effect of a gluten-free diet on the lipid profile in patients with celiac disease., Subjects and Methods: We identified 132 patients with celiac disease who adhered to a gluten-free diet and had lipid profiles performed before and after a median of 20.5 months on the diet. The patients lacked diseases that may affect serum lipids., Results: There were significant increases in total cholesterol and high-density lipoprotein (HDL) cholesterol (P < .0001) but not low-density lipoprotein (LDL) cholesterol (P=.06). The LDL/HDL ratio decreased by 0.36+/-0.7 (P < .0001). Both men and women had a significant increase in total cholesterol and HDL and a significant decrease in the LDL/HDL ratio. Only men had increases in LDL (P=.02). The greatest increase in lipid values was seen in those with the lowest initial values. The largest increase in HDL was seen in subjects with more severe disease as indicated by low albumin level and presence of total villous atrophy., Conclusions: Diagnosis of celiac disease and its treatment with a gluten-free diet resulted in improvement in the lipoprotein profile, which included an increase in HDL and a decrease in the LDL/HDL ratio.

Background: Features of the dyslipidemic pattern reported with the use of antiretroviral therapy predict enhanced postprandial lipemia, which is an emerging cardiovascular disease risk factor., Objective: We evaluated the postprandial response to a physiologic, meal-based challenge in HIV-positive subjects without hyperlipidemia., Design: We measured hourly lipid, lipoprotein, glucose, and insulin concentrations during a 13-h period in 25 nonwhite patients (13 women, 12 men): 13 receiving a protease inhibitor (PI)-based regimen (6 nelfinavir and 7 indinavir) and 12 receiving a nonnucleoside reverse transcriptase inhibitor (NNRTI)-based regimen (6 efavirenz and 6 nevirapine)., Results: Mean fasting HDL-cholesterol concentrations were lower in HIV patients than in healthy subjects without HIV infection matched for age, sex, and ethnicity (z score: -0.81 +/- 0.9; P = 0.0001). Fasting triacylglycerol concentrations were not significantly different between HIV-infected patients and healthy subjects but were higher in PI-treated than in NNRTI-treated patients [median (interquartile range): 144 (110-191) and 89 (62-135) mg/dL; P = 0.007]. Average daylong triacylglycerol concentrations, but not incremental concentrations, were higher in the PI group than in the NNRTI group [205% (185-248%) and 125% (78-191%); P < 0.05]. For all HIV-positive patients, the fractional triacylglycerol increase was lower after breakfast than after lunch (20 +/- 18% and 42 +/- 40%, respectively; P < 0.04). Insulin concentrations were higher in PI-treated than in NNRTI-treated patients [22.6 (13.1-29.8) and 11.8 (7.1-19.1) microU/mL; P = 0.01] and increased in both groups in response to each meal, whereas glucose concentrations increased only after breakfast., Conclusions: Despite baseline differences, incremental triacylglycerol and insulin responses to a physiologic caloric load among HIV-positive patients were not significantly affected by differences in the type of antiretroviral therapy.

Background: Several genetic analyses have suggested that lipoprotein lipase (LpL) genotypes causing decreased LpL activity correlate with increased triglyceride concentrations and risk for coronary artery disease. In contrast, in some other studies LpL activity was positively correlated with plasma low-density lipoprotein (LDL) cholesterol concentrations., Objective: To assess whether these different associations represent physiologic differences in lipoprotein metabolism., Methods: We correlated postheparin lipase activities, postprandial lipemia, and fasting lipoprotein concentrations in obese (BMI > or = 30 kg/m2, n = 26) and non-obese (BMI < or = 30 kg/m2, n = 57) individuals. LpL was measured using specific inhibitory antibodies., Results: Surprisingly, LpL activity was significantly correlated with triglyceride area under the curve after a fat load in the non-obese, but not the entire group. Moreover, in non-obese individuals, LpL activity correlated directly (r = 0.40) and hepatic lipase activity correlated inversely (r = -0.32) with high-density lipoprotein (HDL) cholesterol concentrations. These relationships were not found in the obese group, in whom LpL correlated with LDL cholesterol concentrations (r = 0.54)., Conclusions: We conclude that postheparin LpL activity relates to different lipoproteins in obese and non-obese individuals. In obesity, greater LpL activity may enhance conversion of very-low-density lipoprotein cholesterol to LDL cholesterol, whereas in non-obese individuals the correlation is with HDL cholesterol. Whether this is due to differences in the source of LpL (muscle or fat), or to other associated alterations in lipoprotein metabolism is unknown. These results may explain the non-uniformity of correlations between LpL and atherogenic lipoproteins in different populations.

The lipoprotein lipase (LPL) promoter -93T/G transition has previously been reported as having a triglyceride (Tg)-lowering effect, whereas the D9N variant has been shown to have a Tg-raising effect. These two variants were studied in 66 healthy subjects of Hispanic and 42 subjects of African-American origin, who had participated in a study of postprandial lipemia. While the allele frequency of the -93G was significantly different in the Hispanics and African Americans (0.09: 95% CI 0.04-0.13 and 0.28: 95% CI 0.19-0.38; P=0.0001, respectively), the N9 allele frequency was not different (0.06: 95% CI 0.02-0.1 and 0.05: 95% CI 0.002-0.093, respectively). Linkage disequilibrium between the -93T/G and D9N was highly significant in Hispanics (delta=0.67. P=0.0001), compared to delta=0.09 (NS) in African-Americans. In the combined group, compared to individuals with the common genotype (TT/DD; n=71) with fasting plasma Tg of 1.34 (+/-4.5% SEM) mmol/l, carriers of the G/D haplotype (TG/DD + GG/DD; n=25) had significantly lower plasma Tg levels of 1.08 (+/-10% SEM) mmol/l (P < 0.02). After the fat meal, compared to individuals with neither mutation, TT/DD, the effect of the G/D haplotype was to reduce significantly postprandial Tg (P < 0.036). Retinyl palmitate concentration at 5 hrs was significantly lower in G/D carriers than TT/DD individuals (P < 0.05). The lipid-raising effect of the N9 allele in carriers of the -93G (TG/DN + GG/DN) and effect on postprandial Tg clearance was not significant in this group. Thus carriers of the G/D haplotype have lower fasting plasma Tg and reduced alimentary lipemia. This allele may be associated with reduced risk of coronary artery disease.