No causal effects of plasma homocysteine levels on the risk of coronary heart disease or acute myocardial infarction: A Mendelian randomization study.

BACKGROUND: Although many observational studies have shown an association between plasma homocysteine levels and cardiovascular diseases, controversy remains. In this study, we estimated the role of increased plasma homocysteine levels on the etiology of coronary heart disease and acute myocardial infarction. METHODS: A two-sample Mendelian randomization study on disease was conducted, i.e. "coronary heart disease" (n = 184,305) and "acute myocardial infarction" (n = 181,875). Nine single nucleotide polymorphisms, which were genome-wide significantly associated with plasma homocysteine levels in 57,644 subjects from the Coronary ARtery DIsease Genome wide Replication and Meta-analysis (CARDIoGRAM) plus The Coronary Artery Disease (C4D) Genetics (CARDIoGRAMplusC4D) consortium genome-wide association study and were known to be associated at p < 5×10-8, were used as an instrumental variable. RESULTS: None of the nine single nucleotide polymorphisms were associated with coronary heart disease or acute myocardial infarction (p > 0.05 for all). Mendelian randomization analysis revealed no causal effects of plasma homocysteine levels, either on coronary heart disease (inverse variance weighted; odds ratio = 1.015, 95% confidence interval = 0.923-1.106, p = 0.752) or on acute myocardial infarction (inverse variance weighted; odds ratio = 1.037, 95% confidence interval = 0.932-1.142, p = 0.499). The results were consistent in sensitivity analyses using the weighted median and Mendelian randomization-Egger methods, and no directional pleiotropy (p = 0.213 for coronary heart disease and p = 0.343 for acute myocardial infarction) was observed. Sensitivity analyses confirmed that plasma homocysteine levels were not significantly associated with coronary heart disease or acute myocardial infarction. CONCLUSIONS: The findings from this Mendelian randomization study indicate no causal relationship between plasma homocysteine levels and coronary heart disease or acute myocardial infarction. Conflicting findings from observational studies might have resulted from residual confounding or reverse causation.

Genes associated with inflammation may serve as biomarkers for the diagnosis of coronary artery disease and ischaemic stroke.

BACKGROUND: The current research aimed to expound the genes and pathways that are involved in coronary artery disease (CAD) and ischaemic stroke (IS) and the related mechanisms. METHODS: Two array CAD datasets of (GSE66360 and GSE97320) and an array IS dataset (GSE22255) were downloaded. Differentially expressed genes (DEGs) were identified using the limma package. The online tool Database for Annotation, Visualization and Integrated Discovery (DAVID) (version 6.8; david.abcc.ncifcrf.gov) was used to annotate the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway and Gene Ontology (GO) enrichment analyses of the DEGs. A protein-protein interaction (PPI) network was constructed by Cytoscape software, and then Molecular Complex Detection (MCODE) analysis was used to screen for hub genes. The hub genes were also confirmed by RT-qPCR and unconditional logistic regression analysis in our CAD and IS patients. RESULTS: A total of 20 common DEGs (all upregulated) were identified between the CAD/IS and control groups. Eleven molecular functions, 3 cellular components, and 49 biological processes were confirmed by GO enrichment analysis, and the 20 common upregulated DEGs were enriched in 21 KEGG pathways. A PPI network including 24 nodes and 68 edges was constructed with the STRING online tool. After MCODE analysis, the top 5 high degree genes, including Jun proto-oncogene (JUN, degree = 9), C-X-C motif chemokine ligand 8 (CXCL8, degree = 9), tumour necrosis factor (TNF, degree = 9), suppressor of cytokine signalling 3 (SOCS3, degree = 8) and TNF alpha induced protein 3 (TNFAIP3, degree = 8) were noted. RT-qPCR results demonstrated that the expression levels of CXCL8 were increased in IS patients than in normal participants and the expression levels of SOCS3, TNF and TNFAIP were higher in CAD/IS patients than in normal participants. Meanwhile, unconditional logistic regression analysis revealed that the incidence of CAD or IS was positively correlated with the CXCL8, SOCS3, TNF and TNFAIP3. CONCLUSIONS: The CXCL8, TNF, SOCS3 and TNFAIP3 associated with inflammation may serve as biomarkers for the diagnosis of CAD or IS. The possible mechanisms may involve the Toll-like receptor, TNF, NF-kappa B, cytokine-cytokine receptor interactions and the NOD-like receptor signalling pathways.

A novel circRNA-miRNA-mRNA network identifies circ-YOD1 as a biomarker for coronary artery disease.

Circular RNAs (circRNAs) are involved in many physiological functions. Whether circulating circRNAs serve as markers for coronary artery disease (CAD) is unknown. Seven CAD-related microarray datasets were downloaded from the Gene Expression Omnibus (GEO) database and were analyzed using clustering and functional enrichment to identify hub mRNAs and miRNAs. StarBase V3.0 and circinteractome databases were used to predict interactions between circRNAs and miRNAs whereas miRwalk and DIANA TOOLS were used to predict interactions between miRNAs and mRNAs. Altogether, this helped establish a circRNA-miRNA-mRNA triple network for diagnosis of CAD. Five non-coding RNAs (ncRNAs) were identified in our study population with the use of quantitative real-time PCR (RT-PCR). The prognostic values of circYOD1, hsa-miR-21-3p and hsa-miR-296-3p were evaluated using a receiver operating characteristic (ROC) curve. A CAD circRNA-miRNA-mRNA network was established from our analyses containing one circRNA, four miRNAs and thirteen mRNAs. After performing RT-PCR validation between CAD and non-CAD samples, only three ncRNAs of five ncRNAs showed significance for further analysis. The area under ROC curve (AUC) of circ-YOD1 was 0.824, the AUC of hsa-miR-21-3p was 0.731 and hsa-miR-296-3p was 0.776. The pairwise comparison results showed that circ-YOD1 had statistical significance (PYOD1-21 < 0.01 and PYOD1-296 < 0.05). The results of functional enrichment analysis of interacting genes and microRNAs showed that the shared circ-YOD1 may act as a new biomarker for CAD. Our investigation of the triple regulatory networks of circRNA-miRNA-mRNA in CAD revealed circ-YOD1 as a potential biomarker for CAD.

The CXCL12 SNPs and their haplotypes are associated with serum lipid traits.

The relationship among the single nucleotide polymorphisms (SNPs) of the C-X-C motif chemokine ligand 12 gene (CXCL12) and the serum lipid profiles in the Chinese population has rarely been described, especially in somewhat old-fashioned and isolated Maonan minority. The goal of the current study was to elucidate the connection among the CXCL12 rs501120 and rs1746048 SNPs, haplotypes, several environmental factors and serum lipid traits in the Maonan as well as Han populations. Genotyping of the two SNPs, gel electrophoresis and direct sequencing were accomplished in 1,494 distinct subjects (Maonan, 750 and Han, 744) using polymerase chain reaction and restriction fragment length polymorphism. The frequencies of genotypes as well as alleles of the two SNPs were not similar between the two ethnic groups. The rs501120 SNP was related with serum total cholesterol levels, while the rs1746048 SNP was related with serum apolipoprotein (Apo) B levels. Four haplotypes were identified, of which the rs501120A-rs1746048C haplotype was the most common. The haplotypes of rs501120A-rs1746048T increased and rs501120G-rs1746048C decreased the risk of hyperlipidemia (P < 0.001 for each), showing consistent association with the levels of serum triglyceride, ApoA1 and ApoB. These outcomes specify that the CXCL12 SNPs as well as their haplotypes are related to serum lipid levels. Different serum lipid levels between both populations may partially be related to the CXCL12 SNPs, their haplotypes along with several environmental factors.

Suppressor of cytokine signaling 3 A+930-->G (rs4969168) polymorphism is associated with apolipoprotein A1 and low-density lipoprotein cholesterol.

This study aimed to detect the association of the suppressor of cytokine signaling 3 gene (SOCS3) A+930-->G (rs4969168) single nucleotide polymorphism (SNP) and environmental factors with serum lipid levels in the Han and Mulao populations. Genotyping of the SOCS3 A+930-->G (rs4969168) SNP was performed in 752 of Han and 690 of Mulao participants using polymerase chain reaction and restriction fragment length polymorphism. The genotype and allele frequencies were significantly different between the Han and Mulao populations (GG, 57.71% vs. 51.16%, GA, 36.97% vs. 41.16%, AA, 5.32% vs. 7.68%, P = 0.023; G, 76.20% vs. 71.74%, A, 23.80% vs. 28.26%; P = 0.006; respectively). Serum apolipoprotein (Apo) A1 levels in Han were different among the genotypes (P < 0.05). Subgroup analyses showed that the levels of ApoA1 in Han females, and ApoA1 and low-density lipoprotein cholesterol (LDL-C) in Mulao males were different among the genotypes (P < 0.05). Serum lipid parameters were also associated with several environmental factors in both ethnic groups (P < 0.05-0.001). These findings suggest that there may be a racial/ethnic- and/or sex-specific association between the SOCS3 A+930-->G (rs4969168) SNP and serum lipid parameters in some populations.

Sex-specific association of the SPTY2D1 rs7934205 polymorphism and serum lipid levels.

The objective of the present study was to detect the association of the rs7934205 single nucleotide polymorphism (SNP) near the Suppressor of Ty, domain containing 1 gene (SPTY2D1) and serum lipid levels between males and females in the Mulao and Han populations. Genotyping of SPTY2D1 rs7934205 SNP was performed in 933 of Mulao and 865 of Han participants using polymerase chain reaction and restriction fragment length polymorphism. The T allele frequency was different between Mulao males and females (23.2% vs. 27.9%, P = 0.018). The genotype and allele frequencies were also different between Han males and females (P = 0.020 and P = 0.004; respectively). Serum levels of apolipoprotein (Apo) A1 in Mulao males; and total cholesterol (TC), triglyceride (TG), low-density lipoprotein cholesterol (LDL-C), ApoA1 and ApoB in Mulao females were different between the CC and CT/TT genotypes (P < 0.05). Serum TC, ApoB levels in Han males, and ApoB levels in Han females were different between the CC and CT/TT genotypes (P < 0.05). The subjects with CT/TT genotype in both Mulao and Han males and females have more favorable lipid profiles than those with CC genotype. These findings suggest that the association between the SPTY2D1 rs7934205 SNP and serum lipid levels might have ethnic- and/or sex-specificity.

Association of the SPT2 chromatin protein domain containing 1 gene rs17579600 polymorphism and serum lipid traits.

SPT2 chromatin protein domain containing 1 gene (SPTY2D1) is a candidate gene for dyslipidemia. The single nucleotide polymorphism (SNP) of rs7934205 near SPTY2D1 locus was ethnic- and sex-specific associated with serum lipid levels in our previous study. Whether SPTY2D1 rs17579600 SNP and several environmental factors are associated with serum lipid profiles is unknown. A total of 712 participants of Han and 689 unrelated individuals of Mulao were included. The genotype and allele frequencies of SPTY2D1 rs17579600 SNP were different between the Han and Mulao populations (TT, 74.3% vs. 55.7%; TC, 17.6% vs. 31.2%, CC, 8.1% vs. 13.1%, P = 0.028; T, 83.1% vs. 71.3%; C, 16.9% vs. 28.7%, P = 0.044), and between males and females in the both ethnic groups. The levels of serum apolipoprotein (Apo) A1 in Han, triglyceride (TG) in Mulao, and total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), ApoA1 and ApoB in Mulao males were difference among the genotypes. The C allele carriers had higher ApoA1 in Han, lower TG in Mulao, and lower TC, LDL-C and ApoB and higher ApoA1 in Mulao males than the C allele non-carriers. Serum lipid parameters were also associated with several environmental factors in both ethnic groups. The differences suggesting there may be a racial/ethnic- and/or sex-specific association between the SPTY2D1 rs17579600 SNP and serum lipid parameters in some ethnic groups.