Dysbetalipoproteinemia: Differentiating Multifactorial Remnant Cholesterol Disease From Genetic ApoE Deficiency

Relationship between residual cholesterol and cognitive performance: a study based on NHANES

Background and aims

Age-related cognitive impairment impacts a significant portion of the elderly population. Remnant cholesterol (RC) has attracted increased attention in relation to cardiovascular disease, diabetes, hypertension, and fatty liver disease. Nevertheless, its role in cognitive function is still enigmatic, prompting our exploration into the potential associations between them.

Methods

A total of 1,331 participants from the NHANES (2011-2014) database, all aged over 60, were included in this investigation. Cognitive function was assessed using four widely applied tests, including the Consortium to Establish a Registry for Alzheimer's Disease Word Learning (CERAD-WL), CERAD Delayed Recall (CERAD-DR), Animal Fluency Test (AFT), as well as Digit Symbol Substitution test (DSST). Z-score is calculated by scores from the above four tests. The association between RC, total cholesterol (TC) to RC and cognitive performance was assessed by logistic regression analyses. In addition, restricted cubic spline (RCS) regression was performed to assess non-linearity between RC and cognitive function. Subgroup analysis was performed to evaluate the robustness of the results in populations with relevant covariate variables.

Results

Those with Z-scores below the 25% quartile are defined as having cognitive impairment, totaling 498 individuals. Observationally, higher RC levels and a lower TC/RC were associated with an increased risk of cognitive impairment. After adjusting for confounding factors, the impact of RC levels on cognitive performance quartiles was consistent across various subgroups, except in individuals with trouble sleeping, no/unknown alcohol use, and no hypertension. Americans with high RC levels and trouble sleeping are more likely to develop cognitive impairment, with an odds ratio of 2.33 (95% CI: 1.18-4.59).

Conclusion

This study suggests that higher RC levels and lower levels of TC/RC are associated with an increased likelihood of cognitive impairment, suggesting that RC can serve as a novel and convenient indicator for predicting the risk of cognitive impairment in the US population.

Cardiac Autonomic Neuropathy Is Not Associated with Apolipoprotein E Gene Isoforms in the Kazakh Population: A Case-Control Study

The absence of an early diagnosis of cardiac autonomic neuropathy might increase the risk of the disease, progressing to an irreversible stage. Therefore, this study aims to investigate the APOE gene isoforms in patients with cardiac autonomic neuropathy to identify early markers for predicting this disease in the Kazakh population. A total of 147 patients with cardiac neuropathy and 153 controls were examined in this case-control study. Patients were genotyped for two polymorphisms of the APOE gene using real-time PCR. Statistical calculations were performed using binary logistic regression. As a result of our study, we found that there was no statistically significant difference in the frequency of any APOE gene isoforms (APOE (ε2/ε2), APOE (ε2/ε3), APOE (ε2/ε4), APOE (ε3/ε3), or APOE (ε4/ε4)) between the patient group and the control group (p = 0.69, p = 0.64, p = 0.19, p = 0.22, p = 0.97, respectively). Thus, cardiac autonomic neuropathy is not associated with APOE gene isoforms in the Kazakh population.

Pancreatic and cardiometabolic complications of severe hypertriglyceridaemia

PURPOSE OF REVIEW

This review endeavours to explore the aetiopathogenesis and impact of severe hypertriglyceridemia (SHTG) and chylomicronaemia on cardiovascular, and pancreatic complications and summarizes the novel pharmacological options for management.

RECENT FINDINGS

SHTG, although rare, presents significant diagnostic and therapeutic challenges. Familial chylomicronaemia syndrome (FCS), is the rare monogenic form of SHTG, associated with increased acute pancreatitis (AP) risk, whereas relatively common multifactorial chylomicronaemia syndrome (MCS) leans more towards cardiovascular complications. Despite the introduction and validation of the FCS Score, FCS continues to be underdiagnosed and diagnosis is often delayed. Longitudinal data on disease progression remains scant. SHTG-induced AP remains a life-threatening concern, with conservative treatment as the cornerstone while blood purification techniques offer limited additional benefit. Conventional lipid-lowering medications exhibit minimal efficacy, underscoring the growing interest in novel therapeutic avenues, that is, antisense oligonucleotides (ASO) and short interfering RNA (siRNA) targeting apolipoprotein C3 (ApoC3) and angiopoietin-like protein 3 and/or 8 (ANGPTL3/8).

SUMMARY

Despite advancements in understanding the genetic basis and pathogenesis of SHTG, diagnostic and therapeutic challenges persist. The rarity of FCS and the heterogenous phenotype of MCS underscore the need for the development of predictive models for complications and tailored personalized treatment strategies. The establishment of national and international registries is advocated to augment disease comprehension and identify high-risk individuals.

Molecular genetic testing and measurement of levels of GPIHBP1 autoantibodies in patients with severe hypertriglyceridemia: The importance of identifying the underlying cause of hypertriglyceridemia

BACKGROUND

Severe hypertriglyceridemia can be caused by pathogenic variants in genes encoding proteins involved in the metabolism of triglyceride-rich lipoproteins. A key protein in this respect is lipoprotein lipase (LPL) which hydrolyzes triglycerides in these lipoproteins. Another important protein is glycosylphosphatidylinositol-anchored high density lipoprotein-binding protein 1 (GPIHBP1) which transports LPL to the luminal side of the endothelial cells.

OBJECTIVE

Our objective was to identify a genetic cause of hypertriglyceridemia in 459 consecutive unrelated subjects with levels of serum triglycerides ≥20 mmol/l. These patients had been referred for molecular genetic testing from 1998 to 2021. In addition, we wanted to study whether GPIHBP1 autoantibodies also were a cause of hypertriglyceridemia.

METHODS

Molecular genetic analyses of the genes encoding LPL, GPIHBP1, apolipoprotein C2, lipase maturation factor 1 and apolipoprotein A5 as well as apolipoprotein E genotyping, were performed in all 459 patients. Serum was obtained from 132 of the patients for measurement of GPIHBP1 autoantibodies approximately nine years after molecular genetic testing was performed.

RESULTS

A monogenic cause was found in four of the 459 (0.9%) patients, and nine (2.0%) patients had dyslipoproteinemia due to homozygosity for apolipoprotein E2. One of the 132 (0.8%) patients had GPIHBP1 autoantibody syndrome.

CONCLUSION

Only 0.9% of the patients had monogenic hypertriglyceridemia, and only 0.8% had GPIHBP1 autoantibody syndrome. The latter figure is most likely an underestimate because serum samples were obtained approximately nine years after hypertriglyceridemia was first identified. There is a need to implement measurement of GPIHBP1 autoantibodies in clinical medicine to secure that proper therapeutic actions are taken.

Dietary recommendations for dysbetalipoproteinemia: A need for better evidence

The increased risk of cardiovascular disease in patients with dysbetalipoproteinemia (DBL) is well documented and is associated with the dysfunctional metabolism of remnant lipoproteins. Although these patients are known to respond well to lipid-lowering medication including statins and fibrates, the best dietary approach to lower remnant lipoprotein accumulation and to prevent cardiovascular outcomes remain unclear. Indeed, current evidence is based on studies published mainly in the 1970s, which comprise small sample sizes and methodological limitations. This review aims to summarize nutritional studies performed in DBL patients to date and to discuss potential avenues in this field and future areas of research.

Nutrition interventions for adults with dyslipidemia: A Clinical Perspective from the National Lipid Association

Lifestyle habits can have a profound impact on atherosclerotic cardiovascular disease (ASCVD) risk. The National Lipid Association previously published recommendations for lifestyle therapies to manage dyslipidemia. This Clinical Perspective provides an update with a focus on nutrition interventions for the three most common dyslipidemias in adults: 1) low-density lipoprotein cholesterol (LDL-C) elevation; 2) triglyceride (TG) elevation, including severe hypertriglyceridemia with chylomicronemia; and 3) combined dyslipidemia, with elevations in both LDL-C and TG levels. Lowering LDL-C and non-high-density lipoprotein cholesterol are the primary objectives for reducing ASCVD risk. With severe TG elevation (≥500 mg/dL), the primary objective is to prevent pancreatitis and ASCVD risk reduction is secondary. Nutrition interventions that lower LDL-C levels include reducing cholesterol-raising fatty acids and dietary cholesterol, as well as increasing intakes of unsaturated fatty acids, plant proteins, viscous fibers, and reducing adiposity for patients with overweight or obesity. Selected dietary supplements may be employed as dietary adjuncts. Nutrition interventions for all patients with elevated TG levels include restricting intakes of alcohol, added sugars, and refined starches. Additional lifestyle factors that reduce TG levels are participating in daily physical activity and reducing adiposity in patients with overweight or obesity. For patients with severe hypertriglyceridemia, an individualized approach is essential. Nutrition interventions for addressing concurrent elevations in LDL-C and TG include a combination of the strategies described for lowering LDL-C and TG. A multidisciplinary approach is recommended to facilitate success in making and sustaining dietary changes and the assistance of a registered dietitian nutritionist is highly recommended.

Dysbetalipoproteinemia Is Associated With Increased Risk of Coronary and Peripheral Vascular Disease

CONTEXT

Dysbetalipoproteinemia (DBL) is a disorder in which remnant lipoproteins accumulate in the plasma due to a genetic apolipoprotein E dysfunction in conjunction with the presence of secondary metabolic factors. An increased risk of both coronary and peripheral vascular disease (PVD) has been observed in these patients in retrospective studies.

OBJECTIVE

The primary objective was to compare the incidence of atherosclerotic cardiovascular disease (ASCVD) and PVD in a cohort of patients with DBL compared with normolipidemic controls. As a secondary objective, the incidence of ASCVD and PVD was compared between patients with DBL and patients with familial hypercholesterolemia (FH).

METHODS

A total of 221 patients with DBL, 725 patients with FH, and 1481 normolipidemic controls were included in the study. The data were obtained by review of medical records.

RESULTS

In patients with DBL, there was an overall excess risk of PVD (hazard ratio [HR] 13.58, 95% CI 4.76-38.75) and ASCVD (HR 3.55, 95% CI 2.17-5.83) (P < .0001) when compared with normolipidemic controls. When compared with patients with FH, an increased risk of PVD (HR 3.89, 95% CI 1.20-12.55, P = .02) was observed in patients with DBL.

CONCLUSION

We demonstrated that the risks of ASCVD and PVD in DBL are >3-fold and >13-fold higher, respectively, than normolipidemic controls. Furthermore, the risk of PVD is ∼4-fold higher in DBL than in FH. Adequate screening of DBL is imperative to improve the clinical care of these patients by preventing the development of ASCVD.

Association between remnant cholesterol and verbal learning and memory function in the elderly in the US

BACKGROUND

The relationship between remnant cholesterol (RC) and atherosclerotic cardiovascular risk has been given increasing attention in recent years. However, its association with verbal learning and memory performance has not been reported.

METHODS

Data were extracted from the National Health and Nutrition Examination Survey (NHANES) 2011-2014 database. Participants aged ≥60 years with available fasting lipid data were included. Verbal learning and memory performance were evaluated using the Consortium to Establish a Registry for Alzheimer's Disease Word List Memory Task (CERAD-WL) subtest. The CERAD total score was calculated as the mean of three immediate recalls and a delayed recall. RC was calculated as total cholesterol (TC) minus the sum of low-density lipoprotein cholesterol (LDL-C) and high-density lipoprotein cholesterol (HDL-C). Multivariate ordinal logistic regression was performed to evaluate the association between RC, as well as its derived marker, the TC/RC ratio, and age-stratified quartiles of the CERAD total score.

RESULTS

A total of 1377 participants were analysed. On a continuous scale, per 1 mmol/L increase in RC and per 1 unit increase in the TC/RC ratio were associated with multivariable adjusted odds ratios (95% CI) of 0.74 (0.58-0.94) and 1.45 (1.13-1.87), respectively, for having a CERAD total score in a higher quartile. On a categorical scale, higher RC quartiles were associated with a CERAD total score in a lower quartile; in contrast, the higher TC/RC quartile was associated with a CERAD total score in a higher quartile (all P for trend < 0.05).

CONCLUSIONS

The current study suggests that lower RC levels and a higher TC/RC ratio are associated with better verbal learning and memory function, which indicates that lowering RC levels could be beneficial for preventing cognitive impairment in elderly individuals. Further research is needed to validate the causal roles of RC and the TC/RC ratio in cognition.

Diagnosis of remnant hyperlipidaemia

PURPOSE OF REVIEW

In recent years, there has been interest for the development of simplified diagnosis algorithms of dysbetalipoproteinemia (DBL) in order to avoid the complex testing associated with the Fredrickson criteria (reference method). The purpose of this review is to present recent advances in the field of DBL with a focus on screening and diagnosis.

RECENT FINDINGS

Recently, two different multi-step algorithms for the diagnosis of DBL have been published and their performance has been compared to the Fredrickson criteria. Furthermore, a recent large study demonstrated that only a minority (38%) of DBL patients are carriers of the E2/E2 genotype and that these individuals presented a more severe phenotype.

SUMMARY

The current literature supports the fact that the DBL phenotype is more heterogeneous and complex than previously thought. Indeed, DBL patients can present with either mild or more severe phenotypes that can be distinguished as multifactorial remnant cholesterol disease and genetic apolipoprotein B deficiency. Measurement of apolipoprotein B as well as APOE gene testing are both essential elements in the diagnosis of DBL.

Increased Remnant Lipoproteins in Apo E Deficient Mice Induce Coronary Atherosclerosis following Transverse Aortic Constriction and Aggravate the Development of Pressure Overload-Induced Cardiac Hypertrophy and Heart Failure

Murine coronary arteries are very resistant to the development of atherosclerosis, which may be related to their intramyocardial course. Blood pressure promotes atherosclerotic plaque formation by acting as a physical force that potentiates the migration of pro-atherogenic lipoproteins across the endothelium. C57BL/6N apolipoprotein (apo) E deficient mice have increased remnant lipoproteins that are a risk factor for coronary atherosclerosis. In this study, our aim was to quantify coronary atherosclerosis and artery remodeling following transverse aortic constriction (TAC) in C57BL/6N apo E−/− mice and to evaluate the impact of increased remnant lipoproteins on the development of pressure overload-induced cardiac hypertrophy and heart failure. Advanced atherosclerotic lesions were observed in the left coronary artery of C57BL/6N apo E−/− TAC mice but not in C57BL/6N TAC mice. Pressure overload resulted in markedly increased cardiac hypertrophy and more pronounced heart failure in C57BL/6N apo E−/− TAC mice in comparison to C57BL/6N TAC mice. Pathological hypertrophy, as evidenced by increased myocardial fibrosis and capillary rarefaction, was more prominent in C57BL/6N TAC apo E−/− than in C57BL/6N TAC mice and led to more marked cardiac dysfunction. In conclusion, TAC in apo E deficient mice induces coronary atherosclerosis and aggravates the development of pathological cardiac hypertrophy and heart failure.

Establishing the relationship between Familial Dysbetalipoproteinemia and genetic variants in the APOE gene

Familial Dysbetalipoproteinemia (FD) is the second most common monogenic dyslipidemia and is associated with a very high cardiovascular risk due to cholesterol‐enriched remnant lipoproteins. FD is usually caused by a recessively inherited variant in the APOE gene (ε2ε2), but variants with dominant inheritance have also been described. The typical dysbetalipoproteinemia phenotype has a delayed onset and requires a metabolic hit. Therefore, the diagnosis of FD should be made by demonstrating both the genotype and dysbetalipoproteinemia phenotype. Next Generation Sequencing is becoming more widely available and can reveal variants in the APOE gene for which the relation with FD is unknown or uncertain. In this article, two approaches are presented to ascertain the relationship of a new variant in the APOE gene with FD. The comprehensive approach consists of determining the pathogenicity of the variant and its causal relationship with FD by confirming a dysbetalipoproteinemia phenotype, and performing in vitro functional tests and, optionally, in vivo postprandial clearance studies. When this is not feasible, a second, pragmatic approach within reach of clinical practice can be followed for individual patients to make decisions on treatment, follow‐up, and family counseling.