Protocol for oil red O staining of low-density lipoproteins for in vivo cell treatment.

Low-density lipoproteins (LDLs) are the most abundant circulating lipoproteins and the most critical factor in the development of atherosclerosis. This protocol allows the staining of LDLs with oil red O to monitor particle uptake in bright-field microscopy. Here, we describe how to stain isolated LDLs using oil red O and how to use them to monitor LDL uptake in time-lapse experiments or fixed cells.

Genetic heterogeneity of familial hypercholesterolaemia in two populations from two different countries.

BACKGROUND: Familial hypercholesterolemia (FH) is a genetically determined monogenic disorder of predominantly autosomal dominant inheritance. A number of studies on differences in the genetic profile of patients with FH have demonstrated the importance of a more substantive evaluation of genetic features. The aim of this study was to evaluate the genetic profile of patients with clinical FH among Italian and Russian patients. METHODS: We included 144 Italian and 79 Russian FH patients; clinical diagnosis was based on the same criteria. Patients were divided in: positive to genetic test (one causative variant), inconclusive (only variants of uncertain clinical significance [VUS]), and negative (with likely benign/benign variants, heterozygous variants in LDLRAP1 gene, or without causative variants). RESULTS: The genetic test was positive in 76.4 % of the Italian patients and in 49.4 % of the Russian patients. The presence of VUS alone was detected in 7.6 % and in 19.0 % (p < 0.001), respectively. Among patients with positive genetic diagnosis, pre-treatment LDL-C levels were higher in the Russian cohort (353.5 ± 111.3 vs. 302.7 ± 52.1 mg/dL, p = 0.009), as well as the percentage of treated patients (53.8 % vs. 14.5 %, p < 0.001) and the prevalence of premature coronary heart disease (12.8 % vs. 3.6 %, p = 0.039). Among patients carrying only VUS, mean pre-treatment LDL-C levels were similar between the cohorts (299.5 ± 68.1 vs. 295.3 ± 46.8 mg/dL, p = 0.863). Among pathogenic/likely pathogenic variants and VUS, only 5 % and 4 % was shared between the two cohorts, respectively. CONCLUSION: The genetic background of patients clinically diagnosed with FH in two different countries is characterized by high variability.

ANGPTL3 Deficiency and Risk of Hepatic Steatosis.

BACKGROUND: ANGPTL3 (angiopoietin-like 3) is a therapeutic target for reducing plasma levels of triglycerides and low-density lipoprotein cholesterol. A recent trial with vupanorsen, an antisense oligonucleotide targeting hepatic production of ANGPTL3, reported a dose-dependent increase in hepatic fat. It is unclear whether this adverse effect is due to an on-target effect of inhibiting hepatic ANGPTL3. METHODS: We recruited participants with ANGPTL3 deficiency related to ANGPTL3 loss-of-function (LoF) mutations, along with wild-type (WT) participants from 2 previously characterized cohorts located in Campodimele, Italy, and St. Louis, MO. Magnetic resonance spectroscopy and magnetic resonance proton density fat fraction were performed to measure hepatic fat fraction and the distribution of extrahepatic fat. To estimate the causal relationship between ANGPTL3 and hepatic fat, we generated a genetic instrument of plasma ANGPTL3 levels as a surrogate for hepatic protein synthesis and performed Mendelian randomization analyses with hepatic fat in the UK Biobank study. RESULTS: We recruited participants with complete (n=6) or partial (n=32) ANGPTL3 deficiency related to ANGPTL3 LoF mutations, as well as WT participants (n=92) without LoF mutations. Participants with ANGPTL3 deficiency exhibited significantly lower total cholesterol (complete deficiency, 78.5 mg/dL; partial deficiency, 172 mg/dL; WT, 188 mg/dL; P<0.05 for both deficiency groups compared with WT), along with plasma triglycerides (complete deficiency, 26 mg/dL; partial deficiency, 79 mg/dL; WT, 88 mg/dL; P<0.05 for both deficiency groups compared with WT) without any significant difference in hepatic fat (complete deficiency, 9.8%; partial deficiency, 10.1%; WT, 9.9%; P>0.05 for both deficiency groups compared with WT) or severity of hepatic steatosis as assessed by magnetic resonance imaging. In addition, ANGPTL3 deficiency did not alter the distribution of extrahepatic fat. Results from Mendelian randomization analyses in 36 703 participants from the UK Biobank demonstrated that genetically determined ANGPTL3 plasma protein levels were causally associated with low-density lipoprotein cholesterol (P=1.7×10-17) and triglycerides (P=3.2×10-18) but not with hepatic fat (P=0.22). CONCLUSIONS: ANGPTL3 deficiency related to LoF mutations in ANGPTL3, as well as genetically determined reduction of plasma ANGPTL3 levels, is not associated with hepatic steatosis. Therapeutic approaches to inhibit ANGPTL3 production in hepatocytes are not necessarily expected to result in the increased risk for hepatic steatosis that was observed with vupanorsen.

The heterogeneous cellular landscape of atherosclerosis: Implications for future research and therapies. A collaborative review from the EAS young fellows.

Single cell technologies, lineage tracing mouse models and advanced imaging techniques unequivocally improved the resolution of the cellular landscape of atherosclerosis. Although the discovery of the heterogeneous nature of the cellular plaque architecture has undoubtedly improved our understanding of the specific cellular states in atherosclerosis progression, it also adds more complexity to current and future research and will change how we approach future drug development. In this review, we will discuss how the revolution of new single cell technologies allowed us to map the cellular networks in the plaque, but we will also address current (technological) limitations that confine us to identify the cellular drivers of the disease and to pinpoint a specific cell state, cell subset or cell surface antigen as new candidate drug target for atherosclerosis.

Effectiveness of clinical scores in predicting coronary artery disease in familial hypercholesterolemia: a coronary computed tomography angiography study.

PURPOSE: One of the major challenges in the management of familial hypercholesterolemia (FH) is the stratification of cardiovascular risk in asymptomatic subjects. Our purpose is to investigate the performance of clinical scoring systems, Montreal-FH-score (MFHS), SAFEHEART risk (SAFEHEART-RE) and FH risk score (FHRS) equations and Dutch Lipid Clinic Network (DLCN) diagnostic score, in predicting extent and severity of CAD at coronary computed tomography angiography (CCTA) in asymptomatic FH. MATERIAL AND METHODS: One-hundred and thirty-nine asymptomatic FH subjects were prospectively enrolled to perform CCTA. MFHS, FHRS, SAFEHEART-RE and DLCN were assessed for each patient. Atherosclerotic burden scores at CCTA (Agatston score [AS], segment stenosis score [SSS]) and CAD-RADS score were calculated and compared to clinical indices. RESULTS: Non-obstructive CAD was found in 109 patients, while 30 patients had a CAD-RADS ≥ 3. Classifying the two groups according to AS, values varied significantly for MFHS (p < 0.001), FHRS (p < 0.001) and SAFEHEART-RE (p = 0.047), while according to SSS only MFHS and FHRS showed significant differences (p < 0.001). MFHS, FHRS and SAFEHEART-RE, but not DLCN, showed significant differences between the two CAD-RADS groups (p < .001). MFHS proved to have the best discriminatory power (AUC = 0.819; 0.703-0.937, p < 0.001) at ROC analysis, followed by FHRS (AUC = 0.795; 0.715-0.875, p < .0001) and SAFEHEART-RE (AUC = .725; .61-.843, p < .001). CONCLUSIONS: Greater values of MFHS, FHRS and SAFEHEART-RE are associated to higher risk of obstructive CAD and might help to select asymptomatic patients that should be referred to CCTA for secondary prevention.

How ANGPTL3 Inhibition Will Help Our Clinical Practice?

PURPOSE OF REVIEW: This review aims to summarize the most recently published literature highlighting the potential of pharmacological inhibition of ANGPTL3 in treating patients suffering from dyslipidemias. The rational for this strategy will be discussed considering evidence describing the role of ANGPTL3 in lipid metabolism and the consequences of its deficiency in humans. RECENT FINDINGS: Recent trials have demonstrated the efficacy and safety of ANGPTL3 inhibition in treating homozygous familial hypercholesterolemia even in those patients carrying biallelic null/null variants, thus supporting the notion that the LDL-lowering effect of ANGPLT3 inhibition is LDLR-independent. The use of ANGPTL3 inhibition strategies has expanded its indications in hypertrygliceridemic patients with functional lipoprotein lipase activity. Contemporarily, the pharmacological research is exploring novel approaches to ANGPTL3 inhibition such as the use of a small interfering RNA targeting the ANGPTL3 transcript in the liver, a protein-based vaccine against ANGPTL3, and a CRISP-Cas-9 method for a liver-selective knock-out of ANGPTL3 gene. First, we will describe the molecular function of ANGPTL3 in lipoprotein metabolism. Then, we will revise the clinical characteristics of individuals carrying loss-of-function mutations of ANGPTL3, a rare condition known as familial hypobetalipoproteinemia type 2 (FHBL2) that represents a unique human model of ANGPTL3 deficiency. Finally, we will examine the lipid-lowering potential of pharmacological inhibition of ANGPTL3 based on the results of clinical trials employing Evinacumab, the first approved fully humanized monoclonal antibody against ANGPTL3. The future perspectives for ANGPTL3 inhibition will also be revised.

Genetically determined deficiency of ANGPTL3 does not alter HDL ability to preserve endothelial homeostasis.

Individuals with loss-of-function mutations in the ANGPTL3 gene express a rare lipid phenotype called Familial Combined Hypolipidemia (FHBL2). FHBL2 individuals show reduced plasma concentrations of total cholesterol and triglycerides as well as of lipoprotein particles, including HDL. This feature is particularly remarkable in homozygotes in whom ANGPTL3 in blood is completely absent. ANGPTL3 acts as a circulating inhibitor of LPL and EL and it is thought that EL hyperactivity is the cause of plasma HDL reduction in FHBL2. Nevertheless, the consequences of ANGTPL3 deficiency on HDL functionality have been poorly explored. In this report, HDL isolated from homozygous and heterozygous FHBL2 individuals were evaluated for their ability to preserve endothelial homeostasis as compared to control HDL. It was found that only the complete absence of ANGPTL3 alters HDL subclass distribution, as homozygous, but not heterozygous, carriers have reduced content of large and increased content of small HDL with no alterations in HDL2 and HDL3 size. The plasma content of preß-HDL was reduced in carriers and showed a positive correlation with plasma ANGPTL3 levels. Changes in composition did not however alter the functionality of FHBL2 HDL, as particles isolated from carriers retained their capacity to promote NO production and to inhibit VCAM-1 expression in endothelial cells. Furthermore, no significant changes in circulating levels of soluble ICAM-1 and E-selectin were detected in carriers. These results indicate that changes in HDL composition associated with the partial or complete absence of ANGPTL3 did not alter some of the potentially anti-atherogenic functions of these lipoproteins.

ANGPTL3 deficiency associates with the expansion of regulatory T cells with reduced lipid content.

BACKGROUND AND AIMS: Angiopoietin-like 3 (ANGPTL3) regulates lipid and glucose metabolism. Loss-of-function mutations in its gene, leading to ANGPTL3 deficiency, cause in humans the familial combined hypolipidemia type 2 (FHBL2) phenotype, characterized by very low concentrations of circulating lipoproteins and reduced risk of atherosclerotic cardiovascular disease. Whether this condition is accompanied by immune dysfunctions is unknown. Regulatory T cells (Tregs) are CD4 T lymphocytes endowed with immune suppressive and atheroprotective functions and sensitive to metabolic signals. By investigating FHBL2, we explored the hypothesis that Tregs expand in response to extreme hypolipidemia, through a modulation of the Treg-intrinsic lipid metabolism. METHODS: Treg frequency, phenotype, and intracellular lipid content were assessed ex vivo from FHBL2 subjects and age- and sex-matched controls, through multiparameter flow cytometry. The response of CD4 T cells from healthy controls to marked hypolipidemia was tested in vitro in low-lipid culture conditions. RESULTS: The ex vivo analysis revealed that FHBL2 subjects showed higher percentages of Tregs with a phenotype undistinguishable from controls and with a lower lipid content, which directly correlated with the concentrations of circulating lipoproteins. In vitro, lipid restriction induced the upregulation of genes of the mevalonate pathway, including those involved in isoprenoid biosynthesis, and concurrently increased the expression of the Treg markers FOXP3 and Helios. The latter event was found to be prenylation-dependent, and likely related to increased IL-2 production and signaling. CONCLUSIONS: Our study demonstrates that FHBL2 is characterized by high Treg frequencies, a feature which may concur to the reduced atherosclerotic risk in this condition. Mechanistically, hypolipidemia may directly favor Treg expansion, through the induction of the mevalonate pathway and the prenylation of key signaling proteins.

Heterogeneity of non-alcoholic fatty liver disease (NAFLD): Implication for cardiovascular risk stratification.

NAFLD is currently considered the most common liver disease worldwide and mounting data support its strong link with atherosclerotic cardiovascular disease (ASCVD). This association is important as cardiovascular disease (CVD) is generally recognized as the leading cause of death in individuals with NAFLD. However, NAFLD represents a heterogeneous condition showing a wide spectrum of clinical and pathophysiological sub-phenotypes with different adverse outcomes ranging from ASCVD to liver damage progression. The contribution to NAFLD pathogenesis of different environmental, metabolic, and genetic factors underlies this heterogeneity. The more frequent phenotype of NAFLD patients is associated with metabolic dysfunctions such as obesity and insulin-resistant syndrome and this has been recently named as Metabolic Associated Fatty Liver disease (MAFLD). However, NAFLD is encountered also in subjects without insulin resistance and metabolic alterations and in whom genetic factors play a major role. It has been suggested that these individuals are at risk of liver disease progression but not of cardiovascular complications. Separating metabolic from genetic factors could be useful in disentangling the intricate relationship between NAFLD and atherosclerosis. In the present review, we aim to address the epidemic of NAFLD, its epidemiologically association with ASCVD complications and the overall mechanisms involved in the pathophysiology of atherosclerotic vascular damage in NAFLD patients. Finally, we will revise the potential role of genetics in identifying disease subtyping and predicting individualised CVD risk.

Efficacy of Long-Term Treatment of Autosomal Recessive Hypercholesterolemia With Lomitapide: A Subanalysis of the Pan-European Lomitapide Study.

Background and aim: Autosomal recessive hypercholesterolemia (ARH) is a rare autosomal recessive disorder of low-density lipoprotein (LDL) metabolism caused by pathogenic variants in the LDLRAP1 gene. Like homozygous familial hypercholesterolemia, ARH is resistant to conventional LDL-lowering medications and causes a high risk of atherosclerotic cardiovascular diseases (ASCVDs) and aortic valve stenosis. Lomitapide is emerging as an efficacious therapy in classical HoFH, but few data are available for ARH. Results: This is a subanalysis carried out on nine ARH patients included in the Pan-European Lomitapide Study. The age at starting lomitapide was 46 (interquartile range (IQR), 39.0-65.5) years, with a median treatment duration of 31.0 (IQR 14.0-40.5) months. At baseline, four (44.4%) patients had hypertension, one (11.1%) had diabetes mellitus, two (22.2%) were active smokers, and five (55.5%) reported ASCVD. The baseline LDL-C was 257.0 (IQR, 165.3-309.2) mg/dL. All patients were on statins plus ezetimibe, three were receiving Lipoprotein apheresis (LA), and one was also receiving proprotein convertase subtilisin/kexin type 9 inhibitors (PCSK9i). The addition of lomitapide (mean dose, 10 mg) resulted in the achievement of a median on-treatment LDL-C of 101.7 mg/dL (IQR, 71.3-138.3; 60.4% reduction from baseline), with a best LDL-C value of 68.0 mg/dL (IQR, 43.7-86.7; 73.5% reduction from baseline). During follow-up, one patient stopped both PCSK9i and LA. Recurrence of ASCVD events was reported in one patient. The median on-treatment aspartate transaminase and alanine transaminase values were 31.1 (IQR, 22.6-48.3) U/L and 31.1 (IQR, 27.2-53.8) U/L, respectively. Among six ARH patients with available fibroscan examination, liver stiffness values recorded at the last visit were within the normal range (median, 4.7 KPa; IQR, 3.6-5.3 KPa). Conclusion: Lomitapide is effective and safe in ARH therapy as well as in classical HoFH.

Differential effects of bariatric surgery on plasma levels of ANGPTL3 and ANGPTL4.

BACKGROUND AND AIM: Angiopoietin-like 3 (ANGPTL3) and 4 (ANGPTL4) are regulators of triglyceride storage and utilization. Bariatric surgery (BS) leads to profound changes in adipose tissue composition and energy metabolism. We evaluated the impact of BS on plasma levels of ANGPTL3 and ANGPTL4. METHODS AND RESULTS: Twenty-seven subjects affected by morbid obesity with or without type 2 diabetes (T2D) underwent Roux-en-Y gastric bypass (RYGB) and 18 patients with advanced T2D received Biliopancreatic Diversion (BPD). Fasting ANGPTL proteins levels, insulin sensitivity (evaluated by euglycemic hyperinsulinemic clamp), total bile acids (TBA) and free fatty acids (FFA) were measured at baseline and 1 year after surgery. Both surgical procedures resulted in the loss of fat mass, improved glucose control, and a ∼2-fold increase of insulin sensitivity. ANGPTL4 levels decreased significantly with both RYGB (26.6 ± 0.6 to 24.4 ± 0.3 ng/mL, p = 0.001) and BPD (27.9 ± 1.5 to 24.0 ± 0.5 ng/mL, p = 0.003). In contrast, ANGPTL3 concentrations did not change after RYGB but rose following BPD (225 ± 20 to 300 ± 15 ng/mL, p = 0.003). By multiple regression analysis, changes after BS in ANGPTL4 were independently associated with changes in blood glucose, (p = 0.0169) whereas changes in ANGPTL3 were associated with variations in FFA (p = 0.008) and insulin sensitivity (p = 0.043). CONCLUSION: Circulating ANGPTL4 is reduced by BS, probably due to the loss of fat mass and improved insulin sensitivity. Conversely, ANGPTL3 levels increased after BPD, but not after RYGB, presumably because of the metabolic changes induced by the malabsorptive effect of BPD.

The Fibrinogen-like Domain of ANGPTL3 Facilitates Lipolysis in 3T3-L1 Cells by Activating the Intracellular Erk Pathway.

BACKGROUND: ANGPTL3 stimulates lipolysis in adipocytes, but the underlying molecular mechanism is yet unknown. The C-terminal fibrinogen-like domain of ANGPTL3 (ANGPTL3-Fld) activates the AKT pathway in endothelial cells. Hence, we evaluated whether ANGPTL3-Fld stimulates lipolysis in adipocytes through the MAPK kinase pathway. MATERIALS AND METHODS: 3T3-L1 adipocytes were treated with isoproterenol (ISO), ANGPTL3-Fld, or both. Lipolysis was evaluated through the release of free fatty acids (FFAs) in the culture medium. The activation status of intracellular kinases was evaluated with and without the inhibition of the BRAF-ERK arm of the MAPK pathway. RESULTS: ANGPTL3-Fld alone was not able to activate lipolysis, while the combination of ANGPTL3-Fld and ISO determined a 10-fold enrichment of the FFA concentration in the culture medium with an incremental effect (twofold) when compared with ISO alone. ANGPTL3-Fld alone inhibited hormone-sensitive lipase (HSL), whereas the treatment with ISO induced the activation of HSL. The net balance of ANGPTL3-Fld and ISO cotreatment resulted in HSL activation. The results indicate that ANGPTL3-Fld generated an intracellular activation signal involving the MAPK-ERK pathway, possibly through the PDGFRß-PLCγ-AMPK axis. CONCLUSION: ANGPTL3-Fld appears to act as a facilitator of lipolysis in adipocytes, and this effect was driven by a signal mediated by a pathway that is different from the canonical ß-adrenergic stimulus.

Metabolic Syndrome but Not Fatty Liver-Associated Genetic Variants Correlates with Glomerular Renal Function Decline in Patients with Non-Alcoholic Fatty Liver Disease.

The association between non-alcoholic fatty liver disease (NAFLD) and chronic kidney disease (CKD) has been extensively demonstrated. Recent studies have focused attention on the role of patatin-like phospholipase domain-containing 3 (PNPLA3) rs738409 polymorphism in the association between NAFLD and CKD in non-metabolic adults and children, but the genetic impact on NAFLD-CKD association is still a matter of debate. The aim of the study was to investigate the impact of PNPLA3, transmembrane 6 superfamily member 2 (TM6SF2), membrane-bound O-acyltransferase domain containing 7 (MBOAT7) and glucokinase regulatory protein (GCKR) gene variants rather than metabolic syndrome features on renal function in a large population of NAFLD patients. The present study is a post hoc analysis of the Plinio Study (ClinicalTrials.gov: NCT04036357). PNPLA3, TM6SF2, MBOAT7 and GCKR genes were analyzed by using real-time PCR with TaqMan probes. Glomerular filtration rate (GFR) was estimated with CKD-EPI. We analyzed 538 NAFLD; 47.2% had GFR < 90 mL/min/1.73 m2 while 5.9% had GFR < 60 mL/min/1.73 m2. The distribution of genotypes was superimposable according to GFR cut-offs. Results from the multivariable regression model did not show any correlation between genotypes and renal function. Conversely, metabolic syndrome was highly associated with GFR < 90 mL/min/1.73 m2 (odds ratio (OR): 1.58 [1.10−2.28]) and arterial hypertension with GFR < 60 mL/min/1.73 m2 (OR: 1.50 [1.05−2.14]). In conclusion, the association between NAFLD and CKD might be related to the shared metabolic risk factors rather than the genetic NAFLD background.

Deep Resequencing of 9 Candidate Genes Identifies a Role for ARAP1 and IGF2BP2 in Modulating Insulin Secretion Adjusted for Insulin Resistance in Obese Southern Europeans.

Type 2 diabetes is characterized by impairment in insulin secretion, with an established genetic contribution. We aimed to evaluate common and low-frequency (1-5%) variants in nine genes strongly associated with insulin secretion by targeted sequencing in subjects selected from the extremes of insulin release measured by the disposition index. Collapsing data by gene and/or function, the association between disposition index and nonsense variants were significant, also after adjustment for confounding factors (OR = 0.25, 95% CI = 0.11-0.59, p = 0.001). Evaluating variants individually, three novel variants in ARAP1, IGF2BP2 and GCK, out of eight reaching significance singularly, remained associated after adjustment. Constructing a genetic risk model combining the effects of the three variants, only carriers of the ARAP1 and IGF2BP2 variants were significantly associated with a reduced probability to be in the lower, worst, extreme of insulin secretion (OR = 0.223, 95% CI = 0.105-0.473, p < 0.001). Observing a high number of normal glucose tolerance between carriers, a regression posthoc analysis was performed. Carriers of genetic risk model variants had higher probability to be normoglycemic, also after adjustment (OR = 2.411, 95% CI = 1.136-5.116, p = 0.022). Thus, in our southern European cohort, nonsense variants in all nine candidate genes showed association with better insulin secretion adjusted for insulin resistance, and we established the role of ARAP1 and IGF2BP2 in modulating insulin secretion.

The role of lipid metabolism in shaping the expansion and the function of regulatory T cells.

Metabolic inflammation, defined as a chronic low-grade inflammation, is implicated in numerous metabolic diseases. In recent years, the role of regulatory T cells (Tregs) as key controllers of metabolic inflammation has emerged, but our comprehension on how different metabolic pathways influence Treg functions needs a deeper understanding. Here we focus on how circulating and intracellular lipid metabolism, in particular cholesterol metabolism, regulates Treg homeostasis, expansion, and functions. Cholesterol is carried through the bloodstream by circulating lipoproteins (chylomicrons, very low-density lipoproteins, low-density lipoproteins). Tregs are equipped with a wide array of metabolic sensors able to perceive and respond to changes in the lipid environment through the activation of different intracellular pathways thus conferring to these cells a crucial metabolic and functional plasticity. Nevertheless, altered cholesterol transport, as observed in genetic dyslipidemias and atherosclerosis, impairs Treg proliferation and function through defective cellular metabolism. The intracellular pathway devoted to the cholesterol synthesis is the mevalonate pathway and several studies have shown that this pathway is essential for Treg stability and suppressive activity. High cholesterol concentrations in the extracellular environment may induce massive accumulation of cholesterol inside the cell thus impairing nutrients sensors and inhibiting the mevalonate pathway. This review summarizes the current knowledge regarding the role of circulating and cellular cholesterol metabolism in the regulation of Treg metabolism and functions. In particular, we will discuss how different pathological conditions affecting cholesterol transport may affect cellular metabolism in Tregs.

Efficacy and safety of lomitapide in homozygous familial hypercholesterolaemia: the pan-European retrospective observational study.

AIMS: Lomitapide is a lipid-lowering agent indicated as an adjunct therapy for adult homozygous familial hypercholesterolaemia (HoFH). This study evaluated the medium-term effectiveness and safety of lomitapide in a large cohort of HoFH patients in Europe. METHODS AND RESULTS: In a multicentre retrospective, observational study including 75 HoFH patients treated with lomitapide in a real-world clinical setting from 9 European countries, low-density lipoprotein cholesterol (LDL-C) changes, adverse events (AEs), and major adverse cardiovascular events (MACE) were assessed. After a median 19 months (interquartile range 11-41 months) of treatment with a mean dosage of 20 mg of lomitapide. Low-density lipoprotein cholesterol decreased by 60%, from baseline 280.5 mg/dL (191.8-405.0 mg/dL) to 121.6 mg/dL (61.0-190.5 mg/dL). At the last visit, 32.0% of patients achieved LDL-C <100 mg/dL and 18.7% <70 mg/dL. At baseline, 38 HoFH patients were receiving LDL apheresis (LA), but after initiation of lomitapide 36.8% of patients discontinued LA. During follow-up, lomitapide was permanently interrupted in 13% of patients. Gastrointestinal AEs occurred in 40% and liver transaminases increased (3-5 × upper limits of normal) in 13% of patients. Among patients with liver ultrasound evaluation (n = 45), a modest increase in hepatic steatosis was noted during treatment; however, liver stiffness measured by elastography in 30 of them remained within the normal range. Among HoFH patients exposed to lomitapide for at least 2 years, MACE incident rate was 7.4 per 1000 person-years in the 2 years after as compared to 21.2 per 1000 person-years before treatment with lomitapide. CONCLUSION: In this medium-term real-world experience, lomitapide proved to be very effective in reducing LDL-C in HoFH. Gastrointestinal AEs were common, but liver safety was reassuring with no sign of increased risk of liver fibrosis. A signal of cardiovascular protection was also observed.

Refinement of pathogenicity classification of variants associated with familial hypercholesterolemia: Implications for clinical diagnosis.

BACKGROUND: The lack of functional evidence for most variants detected during the molecular screening of patients with clinical familial hypercholesterolemia (FH) makes the definitive diagnosis difficult. METHODS: A total of 552 variants in LDLR, APOB, PCSK9 and LDLRAP1 genes found in 449 mutation-positive FH (FH/M+) patients were considered. Pathogenicity update was performed following the American College of Medical Genetics and Genomics (ACMG) guidelines with additional specifications on copy number variants, functional studies, in silico prediction and co-segregation criteria for LDLR, APOB and PCSK9 genes. Pathogenicity of LDLRAP1 variants was updated by using ACMG criteria with no change to original scoring. RESULTS: After reclassification, the proportion of FH/M+ carriers of pathogenic (P) or likely pathogenic (LP) variants, and FH/M+ carriers of likely benign (LB) or benign (B) variants, was higher than that defined by standard criteria (81.5% vs. 79.7% and 7.1% vs. 2.7%). The refinement of pathogenicity classification also reduced the percentage of FH with variants of uncertain significance (VUS) (17.7% vs. 11.4%). After adjustment, the FH diagnosis by refined criteria best predicted LDL-C levels (Padj <0.001). Notably, FH with VUS variants had higher LDL-C than those with LB (all Padj ≤ 0.033), but similar to those with LP variants. CONCLUSION: Accurate variant interpretation best predicts the increase of LDL-C levels and shows its clinical utility in the molecular diagnosis of FH.

Long-term efficacy of lipoprotein apheresis and lomitapide in the treatment of homozygous familial hypercholesterolemia (HoFH): a cross-national retrospective survey.

BACKGROUND: Homozygous familial hypercholesterolemia (HoFH) is a rare life-threatening condition that represents a therapeutic challenge. The vast majority of HoFH patients fail to achieve LDL-C targets when treated with the standard protocol, which associates maximally tolerated dose of lipid-lowering medications with lipoprotein apheresis (LA). Lomitapide is an emerging therapy in HoFH, but its place in the treatment algorithm is disputed because a comparison of its long-term efficacy versus LA in reducing LDL-C burden is not available. We assessed changes in long-term LDL-C burden and goals achievement in two independent HoFH patients' cohorts, one treated with lomitapide in Italy (n = 30) and the other with LA in France (n = 29). RESULTS: The two cohorts differed significantly for genotype (p = 0.004), baseline lipid profile (p < 0.001), age of treatment initiation (p < 0.001), occurrence of cardiovascular disease (p = 0.003) as well as follow-up duration (p < 0.001). The adjunct of lomitapide to conventional lipid-lowering therapies determined an additional 58.0% reduction of last visit LDL-C levels, compared to 37.1% when LA was added (padj = 0.004). Yearly on-treatment LDL-C < 70 mg/dl and < 55 mg/dl goals were only achieved in 45.5% and 13.5% of HoFH patients treated with lomitapide. The long-term exposure to LDL-C burden was found to be higher in LA than in Lomitapide cohort (13,236.1 ± 5492.1 vs. 11,656.6 ± 4730.9 mg/dL-year respectively, padj = 0.002). A trend towards fewer total cardiovascular events was observed in the Lomitapide than in the LA cohort. CONCLUSIONS: In comparison with LA, lomitapide appears to provide a better control of LDL-C in HoFH. Further studies are needed to confirm this data and establish whether this translates into a reduction of cardiovascular risk.

Clinical Implications of Monogenic Versus Polygenic Hypercholesterolemia: Long-Term Response to Treatment, Coronary Atherosclerosis Burden, and Cardiovascular Events.

Background Familial hypercholesterolemia (FH) may arise from deleterious monogenic variants in FH-causing genes as well as from a polygenic cause. We evaluated the relationships between monogenic FH and polygenic hypercholesterolemia in influencing the long-term response to therapy and the risk of atherosclerosis. Methods and Results A cohort of 370 patients with clinically diagnosed FH were screened for monogenic mutations and a low-density lipoprotein-rising genetic risk score >0.69 to identify polygenic cause. Medical records were reviewed to estimate the response to lipid-lowering therapies and the occurrence of major atherosclerotic cardiovascular events during a median follow-up of 31.0 months. A subgroup of patients (n=119) also underwent coronary computed tomographic angiography for the evaluation of coronary artery calcium score and severity of coronary stenosis as compared with 135 controls. Two hundred nine (56.5%) patients with hypercholesterolemia were classified as monogenic (FH/M+), 89 (24.1%) as polygenic, and 72 (19.5%) genetically undefined (FH/M-). The response to lipid-lowering therapy was poorest in monogenic, whereas it was comparable in patients with polygenic hypercholesterolemia and genetically undetermined. Mean coronary artery calcium score and the prevalence of coronary artery calcium >100 units were significantly higher in FH/M+ as compared with both FH/M- and controls. Finally, after adjustments for confounders, we observed a 5-fold higher risk of incident major atherosclerotic cardiovascular events in FH/M+ (hazard ratio, 4.8; 95% CI, 1.06-21.36; Padj=0.041). Conclusions Monogenic cause of FH is associated with lower response to conventional cholesterol-lowering therapies as well as with increased burden of coronary atherosclerosis and risk of atherosclerotic-related events. Genetic testing for hypercholesterolemia is helpful in providing important prognostic information.