Background and Aims

agLDL uptake by LRP1 favors the formation of foam cells from SMC, a key process in atherosclerosis. The Cluster II of the LRP1 receptor, and in particular the C-terminal half of domain CR9, comprising the region Gly¹¹²⁷-Cys¹¹⁴⁰ (P3 peptide), is critical for interaction with agLDL. The P3 peptide, and its stabilized versions, the DP3 retro-enantiomer, inhibits the process of aggregation of LDL by 80-90% in standardized biochemical assays. The objective of this work was to study the effect of DP3 peptide on the formation of foam cells and atherosclerosis in an in vitro and in vivo model, respectively.

Methods

The effectiveness of the DP3 peptide in inhibiting foam cell formation from hcVSMC was analyzed by chromatographic analysis of intracellular lipids and confocal microscopy. The impact of treatment with DP3 in vivo was studied in knockout mice for LDLR to which the peptide was injected subcutaneously during 21 days. Plasma lipid levels were analyzed in an autoanalyzer. The atherosclerosis load in the aortic arch was immunohistochemically.

Results

In the presence of DP3, LDL was not aggregated and did not increase the intracellular accumulation of cholesterol in hcVSMC above physiological levels. These results were confirmed by confocal microscopy experiments. Optical microscopy showed that treatment with the peptide did not alter the viability of the cells. In the murine model, DP3 significantly reduced atherosclerosis induced by a high cholesterol diet.

Conclusions

Peptides derived from LRP1 emerge as potentially useful tools in the treatment of atherosclerosis, particularly in people with LDL prone to aggregation.

Background and Aims

To investigate the pathophysiological functions of apolipoprotein CIII (apoCIII) in lipoprotein metabolism and atherosclerosis along with possible molecular mechanisms.

Methods

We used apoCIII knockout (KO) rabbits generated by zinc finger nuclease technique and compared the plasma lipids and their susceptibility to a cholesterol diet-induced atherosclerosis with wild-type (WT) rabbits.

Results

On a normal chow diet, apoCIII KO rabbits exhibited lower plasma levels of TG (up to 36% reduction) than WT rabbits while total cholesterol (TC) and HDL-cholesterol levels were unchanged. Analysis of lipoproteins isolated by sequential gradient ultracentrifugation revealed that reduced plasma TG levels in KO rabbits were accompanied by 73% reduction of very low-density lipoproteins (VLDLs) and 57% reduction of intermediate-density lipoproteins (IDLs). Furthermore, KO rabbits showed faster clearance rate of intralipid emulsion than WT rabbits. On a cholesterol-rich diet, KO rabbits exhibited constantly lower plasma TC and TG levels than WT rabbits, owing to a remarkable reduction of β-VLDLs, IDLs and LDLs. Aortic atherosclerosis areas were significantly reduced in KO rabbits compared with WT rabbits. Using DiI-labeled β-VLDLs, we found that deletion of apoCIII in β-VLDLs of KO rabbits enhances their uptake by cultured hepatocytes in vitro and exhibited faster clearance in vivo than β-VLDLs of WT rabbits.

Conclusions

These results indicate that apoCIII deficiency facilitates TG-rich lipoprotein catabolism and protects against cholesterol diet-induced atherosclerosis in KO rabbits. Therapeutic inhibition of apoCIII expression may become a novel means for the treatment of hyperlipidemia and atherosclerosis.

Background and Aims

Background:

The identification of genetic factors responsible for familial hypobetalipoproteinemia (FHBL), such as APOB, PCSK9 or ANGPTL3, has led to the development of lipid lowering drugs. 30 to 50% of patients with LDL-c <5^th percentile present with mutations in causal FHBL genes, while a polygenic origin is suspected for the others. Liver steatosis is the main complication of FHBL.

Aims:

This study aims at evaluating the spectrum of genetic factors that drive LDL-c to very low levels in order to: i) assess consequences on plasma lipids and liver enzymes and ii) identify polygenic FHBL patients for genetic research purposes.

Methods

127 patients with LDL-c<5^th percentile adjusted for age and sex were recruited. Targeted-next generation sequencing was performed to screen for monogenic forms of FHBL. A 12-SNPs polygenic risk score (PRS) has been calculate for all patients and 856 matched-population controls. Chronic liver disease was assessed by liver panel test (ALT, AST, GGT).

Results

41(32%) patients carried a monogenic FHBL. Patients without mutation present a significant lower PRS than controls (p<1.0e-08) whereas no difference was observed between mutation-carriers and controls (p=0.83). 36 (28%) patients display polygenic predispositions for hypocholesterolemia. While mutation carriers did not have lower plasma LDL-c, they had more frequently chronic liver disease (ALT: P<0.01; GGT<0.01) than patients with polygenic FHBL.

Conclusions

Our study shows an important polygenic origin for FHBL that can phenocopy the effect of monogenic forms on plasma LDL-c levels. However, patients with polygenic FHBL present a decreased risk for chronic liver disease than mutation carriers.