Dyslipidemia: Genetics, lipoprotein lipase and HindIII polymorphism

Association of HindIII Polymorphism of the Lipoprotein Lipase (LPL) Gene (rs320) and Plasma Metabolic Parameters in a Nigerian Population

Genetic variations in the lipoprotein lipase (LPL) gene including the HindIII polymorphism (rs320) have been reported to modify fat metabolism, adiposity, and body weight. However, little attention has been given to the African population. The present study aimed to investigate the relationship between the rs320 gene polymorphism and a number of metabolic and anthropometric parameters in a sample of the Nigerian population. We recruited 236 participants for the study. The participants were required to sign informed consent forms after which information related to their calorie intake and utilization as well as anthropometric measurements were recorded. Plasma metabolic parameters were subsequently determined using an autoanalyzer. Genotyping for HindIII polymorphism was performed using the PCR-RFLP method. The frequencies (n) of T and G alleles were 0.841 (397) and 0.158 (75), while the frequencies (n) of TT, TG, and GG were 0.691(163), 0.301(71), and 0.01(2), respectively. The population was not in Hardy-Weinberg equilibrium (χ2 = 3.717, df = 1, p = 0.841). The anthropometric parameters, the fasting blood glucose, and low-density lipoprotein cholesterol showed no association with the alleles, while plasma high-density lipoprotein cholesterol and total cholesterol were significantly higher among the G allele carriers. However, triglyceride and total protein were significantly higher among the non-G allele carriers. The LPL HindIII gene polymorphism is associated with changes in plasma lipid profile in a sample of the Nigerian population.

Associations of the PPARα and Lipoprotein Lipase Enzyme Gene Polymorphisms with Dyslipidemia in Obese and Non-obese Males

Background

Peroxisome proliferator-activated receptor α (PPARα) is a nuclear transcription factor responsible for gene expression, particularly those associated with lipid metabolism. The lipoprotein lipase enzyme (LPL) is considered a key enzyme in lipid metabolism and transport. The link between dyslipidemia and obesity is well understood. Dyslipidemia is also an established risk feature for cardiovascular disease. Thus, it becomes progressively essential to identify the role of genetic factors as risk markers for the development of dyslipidemia among obese males.

Methods

A case-control study was performed including 469 males. Anthropometric characteristics and serum lipid profiles such as triglycerides (TG), total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), and high-density lipoprotein cholesterol (HDL-C) were evaluated. Genomic DNA extraction and purification were performed using whole blood samples. Restriction enzyme fragment length polymorphism was used to genotype PPARα and LPL single nucleotide polymorphisms. The associations between these polymorphisms and dyslipidemia were examined.

Results

The CC and CG genotypes of PPARα gene polymorphisms were significantly associated with higher TC and LDL-C levels (P<0.05). The TT genotype of the LPL gene polymorphism was significantly associated with higher TG levels and lower HDL-C levels (P<0.05). In contrast, the GG genotype may have a protective action against dyslipidemia.

Conclusion

The study reaches the interesting conclusion that there was a significant association between PPARα as well as LPL gene polymorphisms and dyslipidemia among obese and non-obese males.

The influence of Helicobacter pylori infection on acute coronary syndrome and lipid metabolism in the Chinese ethnicity

Background

Acute coronary syndrome (ACS) patients frequently present a relatively high prevalence of Helicobacter pylori (H. pylori) infection. H. pylori was previously hypothesized to induce ACS through the regulation of lipid levels. However, the risk of H. pylori-induced ACS varies significantly among different ethnic groups, and the associations between H. pylori and lipid parameters remain unclear. This study aimed to systematically assess the risk of ACS in Chinese populations with H. pylori infection while also evaluating the effects of H. pylori on lipid parameters.

Materials and methods

A hospital-based case-control study involving 280 participants was conducted. Immunoblotting was used for the detection and genotyping of H. pylori. The associations between H. pylori and ACS, as well as lipid parameters, were analyzed via the chi-square test and a multiple logistic regression model.

Results

H. pylori infection significantly increased the risk of ACS among all participants (adjusted odds ratio (OR) = 4.04, 95% confidence interval (CI): 1.76-9.25, P < 0.05), with no associations with virulence factors (cytotoxin-associated gene A (CagA) or vacuole toxin geneA (VacA)). Subgroup analysis revealed a significant increase in the risk of ACS among the elderly population aged 56-64 years with H. pylori infection. Additionally, a substantial association was observed between H. pylori and acute myocardial infarction (AMI). No significant differences were found in lipid parameters, including low-density lipoprotein cholesterol (LDL-C), triglyceride (TG), total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), and the LDL/HDL ratio, between individuals positive and negative for H. pylori infection. Similar results were observed between the ACS group and the control group.

Conclusions

Our study has demonstrated for the first time that H. pylori does not significantly impact lipid metabolism but increases the risk of ACS fourfold in the Chinese population (OR = 4.04, 95% CI: 1.76-9.25). Furthermore, the virulence factors of H. pylori (CagA and VacA) may not be involved in the mechanisms by which they promote the development of ACS. This finding provides additional evidence for the association between H. pylori and ACS among different ethnic groups and refutes the biological mechanism by which H. pylori affects ACS through lipid metabolism regulation. Regular screening for H. pylori and eradication treatment in elderly individuals and those at high risk for ACS may be effective measures for reducing the incidence of ACS. Future research should include multicenter randomized controlled trials and explore host genetics and the effects of H. pylori on the gut microbiota as potential biological pathways linking H. pylori and ACS.

Frequencies of variants in genes associated with dyslipidemias identified in Costa Rican genomes

Dyslipidemias are risk factors in diseases of significant importance to public health, such as atherosclerosis, a condition that contributes to the development of cardiovascular disease. Unhealthy lifestyles, the pre-existence of diseases, and the accumulation of genetic variants in some loci contribute to the development of dyslipidemia. The genetic causality behind these diseases has been studied primarily on populations with extensive European ancestry. Only some studies have explored this topic in Costa Rica, and none have focused on identifying variants that can alter blood lipid levels and quantifying their frequency. To fill this gap, this study focused on identifying variants in 69 genes involved in lipid metabolism using genomes from two studies in Costa Rica. We contrasted the allelic frequencies with those of groups reported in the 1000 Genomes Project and gnomAD and identified potential variants that could influence the development of dyslipidemias. In total, we detected 2,600 variants in the evaluated regions. However, after various filtering steps, we obtained 18 variants that have the potential to alter the function of 16 genes, nine variants have pharmacogenomic or protective implications, eight have high risk in Variant Effect Predictor, and eight were found in other Latin American genetic studies of lipid alterations and the development of dyslipidemia. Some of these variants have been linked to changes in blood lipid levels in other global studies and databases. In future studies, we propose to confirm at least 40 variants of interest from 23 genes in a larger cohort from Costa Rica and Latin American populations to determine their relevance regarding the genetic burden for dyslipidemia. Additionally, more complex studies should arise that include diverse clinical, environmental, and genetic data from patients and controls and functional validation of the variants.

Association of Exosomal miR-34a with Markers of Dyslipidemia and Endothelial Dysfunction in Children and Adolescents with T1DM

OBJECTIVE

Dyslipidemia and endothelial dysfunction are common disorders and major causative factors for atherosclerosis in patients with type 1 diabetes mellitus (T1DM). However, their pathophysiology in young patients with T1DM is still under evaluated. We aimed, for the first time, to assess the expression of exosomal micro-RNA 34a (miR-34a) in serum of children and adolescents with T1DM and correlate this expression with markers of dyslipidemia and endothelial dysfunction.

METHODS

The study included 120 T1DM patients and 100 control subjects. Assessment of miR-34a was performed using quantitative real-time polymerase chain reaction. Lipid profile was assessed on an automated analyzer and serum endoglin and intracellular adhesion molecule (ICAM) concentrations were measured using immunometric methods.

RESULTS

Relative expression of miR-34a and serum endoglin and ICAM concentrations were higher in patients than controls (p=0.001) and in patients with dyslipidemia (42 patients) compared to patients without dyslipidemia (78 patients) (p=0.01). Linear regression analysis revealed a strong independent association between exosomal miR-34a expression and total cholesterol, low-density lipoprotein, serum endoglin and serum ICAM after adjustment for other cofactors. The utility of miR-34a as an indicator for associated dyslipidemia was tested using receiver operator characteristic curve analysis which revealed area under the curve: 0.73 with confidence interval: 0.63-0.83 and p=0.001.

CONCLUSION

This was the first study to show the altered expression of exosomal miR-34a among children and adolescents with T1DM. Moreover, association of miR-34a with markers of dyslipidemia and endothelial dysfunction was identified, suggesting that it could play a role in regulation of lipid metabolism and endothelial function in T1DM.

Association between lipoprotein lipase gene polymorphisms and cardiovascular disease risk factors in European adolescents: The Healthy Lifestyle in Europe by Nutrition in Adolescence study

OBJECTIVES

To examine the association of lipoprotein lipase (LPL) polymorphisms with cardiovascular disease (CVD) risk factors in European adolescents, along with the influence of physical activity on these associations.

METHODS

A total of 13 LPL polymorphisms were genotyped in 1.057 European adolescents (12-18 years old) from the Healthy Lifestyle in Europe by Nutrition in Adolescence Cross-Sectional Study. Serum lipids, glucose, insulin, and leptin (LEP) levels were measured and a CVD risk score was computed. We also measured body weight and height, waist and hip circumferences, and triceps and subscapular skinfold thickness. Physical activity was objectively measured by accelerometry for 7 days.

RESULTS

The rs1534649, rs258, rs320, and rs328 polymorphisms were associated with several CVD risk factors (ie, body mass index, triglycerides [TG], LEP, and cholesterol/high-density lipoprotein [HDL], low-density lipoprotein [LDL]/HDL, TG/HDL ratios). TG and TG/HDL were associated with haplotype blocks 3 (rs282, rs285 polymorphisms) and 4 (rs3126, rs320, rs328, rs10099160 polymorphisms), being the latter also associated with the CVD risk score. Physical activity modulated the association of adiposity with rs1534649 and rs258 polymorphisms.

CONCLUSIONS

Polymorphisms rs1534649, rs258, rs320 and rs328, and two haplotypes of LPL were significantly associated with CVD risk factors in European adolescents. Higher levels of moderate to vigorous physical activity may attenuate the effects of rs1534649 and rs258 polymorphisms on adiposity.

AAV-Mediated ApoC2 Gene Therapy: Reversal of Severe Hypertriglyceridemia and Rescue of Neonatal Death in ApoC2-Deficient Hamsters

Apolipoprotein C2 (ApoC2) is a key activator of lipoprotein lipase for plasma triglyceride metabolism. ApoC2-deficient patients present with severe hypertriglyceridemia and recurrent acute pancreatitis, for whom the only effective treatment is the infusion of normal plasma containing ApoC2. However, since ApoC2 has a fast catabolic rate, a repeated infusion is required, which limits its clinical use. To explore a safe and efficient approach for ApoC2 deficiency, we herein established an adeno-associated virus expressing human ApoC2 (AAV-hApoC2) to evaluate the efficacy and safety of gene therapy in ApoC2-deficient hypertriglyceridemic hamsters. Administration of AAV-hApoC2 via jugular or orbital vein in adult and neonatal ApoC2-deficient hamsters, respectively, could prevent the neonatal death and effectively improve severe hypertriglyceridemia of ApoC2-deficient hamsters without side effects in a long-term manner. Our novel findings in the present study demonstrate that AAV-hApoC2-mediated gene therapy will be a promising therapeutic approach for clinical patients with severe hypertriglyceridemia caused by ApoC2 deficiency.

MicroRNA 27a Is a Key Modulator of Cholesterol Biosynthesis

Hypercholesterolemia is a strong predictor of cardiovascular diseases. The 3-hydroxy-3-methylglutaryl coenzyme A reductase gene (Hmgcr) coding for the rate-limiting enzyme in the cholesterol biosynthesis pathway is a crucial regulator of plasma cholesterol levels. However, the posttranscriptional regulation of Hmgcr remains poorly understood. The main objective of this study was to explore the role of microRNAs (miRNAs) in the regulation of Hmgcr expression. Systematic in silico predictions and experimental analyses reveal that miRNA 27a (miR-27a) specifically interacts with the Hmgcr 3' untranslated region in murine and human hepatocytes. Moreover, our data show that Hmgcr expression is inversely correlated with miR-27a levels in various cultured cell lines and in human and rodent tissues. Actinomycin D chase assays and relevant experiments demonstrate that miR-27a regulates Hmgcr by translational attenuation followed by mRNA degradation. Early growth response 1 (Egr1) regulates miR-27a expression under basal and cholesterol-modulated conditions. miR-27a augmentation via tail vein injection of miR-27a mimic in high-cholesterol-diet-fed Apoe ^-/- mice shows downregulation of hepatic Hmgcr and plasma cholesterol levels. Pathway and gene expression analyses show that miR-27a also targets several other genes (apart from Hmgcr) in the cholesterol biosynthesis pathway. Taken together, miR-27a emerges as a key regulator of cholesterol biosynthesis and has therapeutic potential for the clinical management of hypercholesterolemia.