Lipoprotein (a): Recent Updates on a Unique Lipoprotein

Association between lipoprotein(a), fibrinogen and their combination with all-cause, cardiovascular disease and cancer-related mortality: findings from the NHANES

BACKGROUND

There is evidence indicating that both lipoprotein(a) [Lp(a)] and fibrinogen (FIB) are associated with mortality, However, the impact of their combination on mortality has not been determined. Thus, the aim of this study was to examine the association between the combination of Lp(a) and FIB with all-cause and cause-specific mortality.

METHODS

This prospective cohort study enrolled 4,730 participants from the third National Health and Nutrition Examination Survey. The exposure variables included Lp(a), FIB and their combination, while the outcome variables consisted of all-cause, cardiovascular disease (CVD) and cancer-related mortality. Multivariate COX regression, subgroup analysis, sensitivity analysis and restricted cubic spline (RCS) were used to investigate the association between Lp(a), FIB and their combination with all-cause, CVD and cancer-related mortality.

RESULTS

Over a median follow-up period of 235 months, 2,668 individuals died, including 1,051 deaths attributed to CVD and 549 deaths due to cancer. Multivariate Cox regression analyses revealed independent associations between both Lp(a) and FIB with all-cause, CVD, and cancer-related mortality. Compared to participants in the 1st to 50th percentiles of both Lp(a) and FIB, those in the 90th to 100th percentiles exhibited multivariable adjusted HRs of 1.813 (95% CI: 1.419-2.317, P < 0.001), 2.147 (95% CI: 1.483-3.109, P < 0.001) and 2.355 (95% CI: 1.396, 3.973, P = 0.001) for all-cause, CVD and cancer-related mortality, respectively. Subgroup and sensitivity analyses did not substantially attenuate the association between the combination of high Lp(a) and high FIB with the risk of all-cause and CVD-related mortality. Additionally, the RCS analysis showed that the relationship between Lp(a) and the risk of all-cause and cancer-related mortality, as well as the relationship between FIB and the risk of cancer-related mortality, were linear (P for nonlinearity > 0.05). Conversely, the relationship between Lp(a) and the risk of CVD-related mortality, as well as the relationship between FIB and the risk of all-cause and CVD-related mortality, were nonlinear (P for nonlinearity < 0.05).

CONCLUSIONS

High levels of Lp(a) and FIB together conferred a greater risk of mortality from all-cause, CVD and cancer.

Predicted deleterious variants in ABCA1, LPL, LPA and KIF6 are associated with statin response and adverse events in patients with familial hypercholesterolemia and disturb protein structure and stability

OBJECTIVES

This study explored the association of deleterious variants in pharmacodynamics (PD) genes with statin response and adverse effects in patients with familial hypercholesterolemia (FH) and analyzed their potential effects on protein structure and stability.

METHODS

Clinical and laboratory data were obtained from 144 adult FH patients treated with statins. A panel of 32 PD genes was analyzed by exon-targeted gene sequencing. Deleterious variants were identified using prediction algorithms and their structural effects were analyzed by molecular modeling studies.

RESULTS

A total of 102 variants were predicted as deleterious (83 missense, 8 stop-gain, 4 frameshift, 1 indel, 6 splicing). The variants ABCA1 rs769705621 (indel), LPA rs41267807 (p.Tyr2023Cys) and KIF6 rs20455 (p.Trp719Arg) were associated with reduced low-density lipoprotein cholesterol (LDLc) response to statins, and the LPL rs1801177 (p.Asp36Asn) with increased LDLc response (P < 0.05). LPA rs3124784 (p.Arg2016Cys) was predicted to increase statin response (P = 0.022), and ABCA1 rs769705621 to increase the risk of statin-related adverse events (SRAE) (P = 0.027). LPA p.Arg2016Cys and LPL p.Asn36Asp maintained interactions with solvent, LPA p.Tyr2023Cys reduced intramolecular interaction with Gln1987, and KIF6 p.Trp719Arg did not affect intramolecular interactions. DDMut analysis showed that LPA p.Arg2016Cys and p.Tyr2023Cys and LPL p.Asp36Asn caused energetically favorable changes, and KIF6 p.Trp719Arg resulted in unfavorable energetic changes, affecting protein stability.

CONCLUSION

Deleterious variants in ABCA1, LPA, LPL and KIF6 are associated with variability in LDLc response to statins, and ABCA1 rs769705621 is associated with SRAE risk in FH patients. Molecular modeling studies suggest that LPA p.Tyr2023Cys and KIF6 p.Trp719Arg disturb protein conformational structure and stability.

Intracranial Aneurysms and Lipid Metabolism Disorders: From Molecular Mechanisms to Clinical Implications

Many vascular diseases are linked to lipid metabolism disorders, which cause lipid accumulation and peroxidation in the vascular wall. These processes lead to degenerative changes in the vessel, such as phenotypic transformation of smooth muscle cells and dysfunction and apoptosis of endothelial cells. In intracranial aneurysms, the coexistence of lipid plaques is often observed, indicating localized lipid metabolism disorders. These disorders may impair the function of the vascular wall or result from it. We summarize the literature on the relationship between lipid metabolism disorders and intracranial aneurysms below.

Role of lipoprotein(a) in atherosclerotic cardiovascular disease: A review of current and emerging therapies

Lipoprotein(a), or Lp(a), is structurally like low-density lipoprotein (LDL) but differs in that it contains glycoprotein apolipoprotein(a) [apo(a)]. Due to its prothrombotic and proinflammatory properties, Lp(a) is an independent risk factor for atherosclerotic cardiovascular disease (ASCVD) and aortic valve stenosis. Lp(a) levels are genetically determined, and it is estimated that 20%-25% of the global population has an Lp(a) level ≥50 mg/dL (or ≥125 nmol/L). Diet and lifestyle interventions have little to no effect on Lp(a) levels. Lipoprotein apheresis is the only approved treatment for elevated Lp(a) but is time-intensive for the patient and only modestly effective. Pharmacological approaches to reduce Lp(a) levels and its associated risks are of significant interest; however, currently available lipid-lowering therapies have limited effectiveness in reducing Lp(a) levels. Although statins are first-line agents to reduce LDL cholesterol levels, they modestly increase Lp(a) levels and have not been shown to change Lp(a)-mediated ASCVD risk. Alirocumab, evolocumab, and inclisiran reduce Lp(a) levels by 20-25%, yet the clinical implications of this reduction for Lp(a)-mediated ASCVD risk are uncertain. Niacin also lowers Lp(a) levels; however, its effectiveness in mitigating Lp(a)-mediated ASCVD risk remains unclear, and its side effects have limited its utilization. Recommendations for when to screen and how to manage individuals with elevated Lp(a) vary widely between national and international guidelines and scientific statements. Three investigational compounds targeting Lp(a), including small interfering RNA (siRNA) agents (olpasiran, SLN360) and an antisense oligonucleotide (pelacarsen), are in various stages of development. These compounds block the translation of messenger RNA (mRNA) into apo(a), a key structural component of Lp(a), thereby substantially reducing Lp(a) synthesis in the liver. The purpose of this review is to describe current recommendations for screening and managing elevated Lp(a), describe the effects of currently available lipid-lowering therapies on Lp(a) levels, and provide insight into emerging therapies targeting Lp(a).

Hyperlipoproteinemia (a) and Phytoestrogen Therapy in Dialysis Patients: A Review

PURPOSE

Hyperlipoproteinemia (a) is a prevalent complication in dialysis patients, with no valid treatment strategy. The aim of this narrative review was to investigate the clinical significance of hyperlipoproteinemia (a) and phytoestrogen therapy in dialysis patients.

METHODS

A comprehensive literature search of the published data was performed regarding the effects of phytoestrogen therapy on hyperlipoproteinemia (a) in dialysis patients.

FINDINGS

Hyperlipoproteinemia (a) occurs in dialysis patients due to decreased catabolism and increased synthesis of lipoprotein (a) [Lp(a)]. A few clinical trials have studied the effects of phytoestrogens on serum Lp(a). All studies of dialysis patients or nonuremic individuals with hyperlipoproteinemia (a), except one, showed that phytoestrogens could significantly reduce serum Lp(a) levels. However, all investigations of phytoestrogen therapy in individuals with normal serum Lp(a) levels showed that it had no effect on serum Lp(a). Phytoestrogens seem to have effects similar to those of estrogen in lowering Lp(a) concentrations.

IMPLICATIONS

Considering the high prevalence of hyperlipoproteinemia (a) in dialysis patients, phytoestrogen therapy is a reasonable approach for reducing serum Lp(a) levels and its complications in these patients.

Lipoprotein(a), Cardiovascular Events and Sex Differences: A Single Cardiological Unit Experience

Lipoprotein(a)-Lp(a), which retains proatherogenic and prothrombotic properties, may be modified by hormonal and metabolic factors. However, few studies have focused on differences related to sex and cardiometabolic risk factors in the relationship between Lp(a) and cardiovascular disease, especially in terms of prognosis. This study aimed at evaluating the predictive value of Lp(a) (cut-off 30 mg/dL) for hard events (HEs: mortality and non-fatal myocardial infarction) according to sex and cardiometabolic risk factors in 2110 patients (1501 males, mean age: 68 ± 9 years) undergoing coronary angiography for known or suspected coronary artery disease. There were 211 events over a median follow-up period of 33 months. Lp(a) > 30 mg/dL did not confer a worse prognosis on the overall population. However, Kaplan-Meier subgroup analysis evidenced a worse prognosis in type 2 diabetes (T2D) females with elevated Lp(a) (log-rank test: p = 0.03) vs. T2D males and no-T2D patients, but not in other high-risk cardiovascular states (e.g., smoking, hypertension, reduced left ventricular ejection fraction or obesity). After Cox multivariate adjustment, Lp(a) remained an independent determinant for HEs in the T2D female subgroup, conferring an HR of 2.9 (95% CI 1.1-7.7, p < 0.05). Lp(a) is therefore a strong independent predictor of HR in T2D women, but not in T2D men, or in noT2D patients.

Relationship of low-density lipoprotein-cholesterol and lipoprotein(a) to cardiovascular risk: The Multi-Ethnic Study of Atherosclerosis (MESA)

BACKGROUND AND AIMS

Plasma low-density lipoprotein cholesterol (LDL-C) and lipoprotein(a) (Lp(a)) are both associated with coronary heart disease (CHD). This study investigated whether elevated plasma Lp(a) concentration was associated with increased CHD risk when LDL-C was low (≤100 mg/dL) in individuals not on statin therapy.

METHODS

Participants from the Multi-Ethnic Study of Atherosclerosis (MESA) (n = 4,585) were categorized into four groups: Group 1: LDL-C ≤ 100 mg/dL, Lp(a) < 50 mg/dL; Group 2: LDL-C > 100 mg/dL, Lp(a) < 50 mg/dL; Group 3: LDL-C ≤ 100 mg/dL, Lp(a) ≥ 50 mg/dL; and Group 4: LDL-C > 100 mg/dL, Lp(a) ≥ 50 mg/dL. The relationship of Lp(a) and LDL-C with time to CHD events was assessed with Kaplan Meier curves and multivariable Cox proportional hazard models.

RESULTS

Participants were followed for a mean of 13.4 years and a total of 315 CHD events occurred. Compared to participants with LDL-C ≤ 100 mg/dL and Lp(a) < 50 mg/dL, those with LDL-C > 100 mg/dL and Lp(a) < 50 mg/dL (Group 2) demonstrated no increased risk for CHD events (HR: 0.92; 95% CI: 0.69, 1.21). However, participants with LDL-C ≤ 100 mg/dL and Lp(a) ≥ 50 mg/dL (Group 3) and those with LDL-C > 100 mg/dL and Lp(a) ≥ 50 mg/dL (Group 4) exhibited significantly increased risk of CHD events compared to Group 1 (HR: 1.83; 95% CI: 1.02, 3.27) and Group 2 (HR: 1.61; 95% CI: 1.15, 2.26), respectively.

CONCLUSIONS

When Lp(a) was elevated, risk of CHD events increased, regardless of baseline LDL-C.

Sorting through the extensive and confusing roles of sortilin in metabolic disease

Sortilin is a post-Golgi trafficking receptor homologous to the yeast vacuolar protein sorting receptor 10 (VPS10). The VPS10 motif on sortilin is a 10-bladed β-propeller structure capable of binding more than 50 proteins, covering a wide range of biological functions including lipid and lipoprotein metabolism, neuronal growth and death, inflammation, and lysosomal degradation. Sortilin has a complex cellular trafficking itinerary, where it functions as a receptor in the trans-Golgi network, endosomes, secretory vesicles, multivesicular bodies, and at the cell surface. In addition, sortilin is associated with hypercholesterolemia, Alzheimer's disease, prion diseases, Parkinson's disease, and inflammation syndromes. The 1p13.3 locus containing SORT1, the gene encoding sortilin, carries the strongest association with LDL-C of all loci in human genome-wide association studies. However, the mechanism by which sortilin influences LDL-C is unclear. Here, we review the role sortilin plays in cardiovascular and metabolic diseases and describe in detail the large and often contradictory literature on the role of sortilin in the regulation of LDL-C levels.

PCSK9 Inhibitors in the Management of Cardiovascular Risk: A Practical Guidance

Proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitors are potent medications in the toolkit for treatment of atherosclerotic cardiovascular disease. These agents have been well studied in clinical trials supporting their efficacy in dramatically reducing low-density lipoprotein cholesterol (LDL-C) and impact on cardiovascular outcomes. Since the approval of commercial use for PCSK9 inhibitors in 2015, we have also gained significant experience in the use of these therapeutics in the real-world setting. In this article, we review current guideline recommendations, clinical trial evidence on efficacy and safety as well as data on cost-effectiveness, prescription and adherence. We focus primarily on the monoclonal antibody class of PCSK9 inhibitors in this review while also touching on other types of therapeutics that are under development.

Lipid Profile, Lp(a) Levels, and HDL Quality in Adolescents with Down Syndrome

The improvement in the lifespan of individuals with Down syndrome (DS) has created interest in the context of the development of age-related diseases. Among them is atherosclerosis-based cardiovascular disease (CVD), which seems to be an especially urgent and important issue. The aim of the present study was to evaluate the lipid markers that may clarify cardiovascular risk profiles in individuals with DS. To this end, we analyzed lipid profile parameters, including lipoprotein(a) (Lp(a)) levels, protein composition, and the antioxidative properties of high-density lipoprotein (HDL), in 47 adolescents with DS and 47 individuals without DS. Compared with the control group (C), subjects with DS had significantly increased concentrations of low-density lipoprotein cholesterol (105 ± 31 vs. 90 ± 24 mg/dL, p = 0.014), non-high-density lipoprotein cholesterol (120 ± 32 vs. 103 ± 26 mg/dL, p = 0.006), and triglycerides (72 [55−97] vs. 60 [50−77] mg/dL, p = 0.048). We found that patients with DS were characterized by significantly higher Lp(a) levels (31.9 [21.5−54.3] vs. 5.2 (2.4−16.1) mg/dL, p < 0.001). In fact, 57% of individuals with DS had Lp(a) levels above 30 mg/dL, which was approximately four times higher than those in the control group (DS 57% vs. C 15%). Apart from decreased high-density lipoprotein cholesterol levels in the subjects with DS (53 ± 11 vs. 63 ± 12 mg/dL, p < 0.001), differences in parameters showing the quality of HDL particles were observed. The concentrations of the main proteins characterizing the HDL fraction, apolipoprotein A-I and apolipoprotein A-II, were significantly lower in the DS group (144 ± 21 vs. 181 ± 33 mg/dL, p < 0.001; 33 ± 6 vs. 39 ± 6 mg/dL, p < 0.001, respectively). No significant differences between the groups were observed for the concentration of paraoxonase-1 (DS 779 ± 171 vs. C 657 ± 340 ng/mL, p = 0.063), enzyme activities toward paraoxon (DS 219 [129−286] vs. C 168 [114−272] IU/L, p = 0.949), or phenyl acetate (DS 101 ± 20 vs. C 93 ± 21 kIU/L, p = 0.068). There were no differences in myeloperoxidase activity between the study groups (DS 327 [300−534] vs. C 426 [358−533] ng/mL, p = 0.272). Our results are the first to demonstrate an unfavorable lipid profile combined with higher Lp(a) levels and quality changes in HDL particles in individuals with DS. This sheds new light on cardiovascular risk and traditional healthcare planning for adolescents with DS.

Highlights of Cardiovascular Disease Prevention Studies Presented at the 2022 American College of Cardiology Scientific Sessions

PURPOSE OF REVIEW

Focused review highlighting select studies presented at the 2022 American College of Cardiology (ACC) Scientific Sessions.

RECENT FINDINGS

Included studies assessed the impact of a low-sodium diet on heart failure outcomes (SODIUM-HF); outcomes of pregnant patients with chronic hypertension treated with antihypertensive therapies (CHAP); cardiovascular outcomes in patients with type 2 diabetes and renal impairment treated with sotagliflozin (SCORED); a safety and efficacy study investigating SLN360, a short interfering RNA targeting lipoprotein(a) (APOLLO); a supermarket and web-based intervention targeting nutrition for cardiovascular risk reduction (SuperWIN); a superiority trial comparing myocardial injury following very mild perioperative hypothermia versus aggressive warming after non-cardiac surgery (PROTECT); and 3-year efficacy outcomes of renal denervation on blood pressure reduction from the SPYRAL HTN-ON MED pilot study. Research presented at the 2022 ACC Scientific Sessions underscores the new potential and meaningful impact of cardiovascular disease prevention and management interventions.

Value of repeated measurements of lipoprotein (a) to assess cardiovascular risk: a retrospective study

Background: High plasma concentrations of lipoprotein (a) [Lp(a)] are associated with an increased cardiovascular risk. Current guidelines recommend measurement of only a single Lp(a) in an individual's lifetime under specific circumstances to improve cardiovascular risk prediction. Accordingly, the question raised is the number of false positives and negatives missed through only a single measurement.Methods: All Lp(a) measurements between 2004 and March 2021 were retrieved from the laboratory database of the Erasme hospital. Only patients with repeated measurement were included. The first and subsequent Lp(a) measurement were compared. Two different cohorts were studied as a result of a change in Lp(a) determination methodology (n = 2049 and n = 309, respectively). The effects of a third Lp(a) measurement were assessed through binary analyses (n = 678). The 180 mg/dl (430 nmol/L) threshold recommended in the ESC guidelines was assessed first. Analysis was repeated for 100, 70 and 50 mg/dl thresholds of raised Lp(a) levels.Results: A low rate of false negatives (0.8%-1%) and false positives (0.6-0.3%) were revealed with two Lp(a) measurements. There was no difference in regards to the divergent Lp(a) thresholds nor the measurement of Lp(a) on two or three occasions.Conclusion: The present study showed Lp(a) determination to be reproducible. A single measurement is sufficient to assess if a patient exceeds various cut-off values of elevated Lp(a) levels.

Lipoprotein (a) and Cardiovascular Disease: A Missing Link for Premature Atherosclerotic Heart Disease and/or Residual Risk

ABSTRACT

Lipoprotein(a) or lipoprotein "little a" is an under-recognized causal risk factor for cardiovascular (CV) disease (CVD), including coronary atherosclerosis, aortic valvular stenosis, ischemic stroke, heart failure and peripheral arterial disease. Elevated plasma Lp(a) (≥50 mg/dL or ≥100 nmol/L) is commonly encountered in almost 1 in 5 individuals and confers a higher CV risk compared to those with normal Lp(a) levels, although such normal levels have not been generally agreed upon. Elevated Lp(a) is considered a cause of premature and accelerated atherosclerotic CVD. Thus, in patients with a positive family or personal history of premature coronary artery disease (CAD), Lp(a) should be measured. However, elevated Lp(a) may confer increased risk for incident CAD even in the absence of a family history of CAD, and even in those who have guideline-lowered LDL-cholesterol (<70 mg/dl) and continue to have a persisting CV residual risk. Thus, measurement of Lp(a) will have a significant clinical impact on the assessment of atherosclerotic CVD risk, and will assume a more important role in managing patients with CVD with the advent and clinical application of specific Lp(a)-lowering therapies. Conventional therapeutic approaches like lifestyle modification and statin therapy remain ineffective at lowering Lp(a). Newer treatment modalities, such as gene silencing via RNA interference with use of antisense oligonucleotide(s) or small interfering RNA molecules targeting Lp(a) seem very promising. These issues are herein reviewed, accumulated data are scrutinized, meta-analyses and current guidelines are tabulated and Lp(a)-related CVDs and newer therapeutic modalities are pictorially illustrated.