APOA1/A5 variants and haplotypes as a risk factor for obesity and better lipid profiles in a Brazilian Elderly Cohort

The APOA5-rs662799 Polymorphism Is a Determinant of Dyslipidemia in Vietnamese Primary School Children

Apolipoprotein A-V encoded by apolipoprotein 5 (APOA5) gene plays an important role in lipid metabolism, especially in the regulation of plasma triglycerol levels. The study aimed to evaluate the association of the APOA5-rs662799 polymorphism with dyslipidemia in Vietnamese children and the potential modification of obesity-related traits (body mass index, waist circumference, hip circumference, and waist-to-hip ratio) on this association. A case-control study was conducted with a total of 154 dyslipidemia cases and 389 controls at the age of 6 to 10 recruited at 31 primary schools in Hanoi city of Vietnam. Genotype for APOA5-rs662799 polymorphism was determined by the restriction fragment length polymorphism analysis. The association of APOA5-rs662799 polymorphism with dyslipidemia adjusting for age, sex, residence, and obesity-related traits was analyzed by binary logistic regression analysis. The results showed that in comparison with T/T and T/C carriers, the C/C carriers had a higher concentration of serum TAG in cases (p =0.049). Carriers of the C allele (C/C + T/C) had higher risk for developing dyslipidemia and hypertriglyceridemia than subjects with T/T genotype (odds ratio, OR = 1.7, p =0.0062 and OR = 1.6, p = 0.026, respectively). The association remained significant after adjusting for age, gender, residence, and obesity status (OR = 1.75, p = 0.006 and OR = 1.53, p = 0.049, respectively) or other obesity-related traits. The study suggested that the APOA5-rs662799 polymorphism may be a determinant of dyslipidemia and hypertriglyceridemia in Vietnamese children, independent of obesity-related traits.

Network pharmacology-based identification for therapeutic mechanism of Ling-Gui-Zhu-Gan decoction in the metabolic syndrome induced by antipsychotic drugs

BACKGROUND

The metabolic syndrome (MetS) is a common side effect of second-generation antipsychotic drugs (SGAs), leading to poor prognosis in patients with mental illness. The traditional Chinese herbal formula Ling-Gui-Zhu-Gan decoction (LGZGD) is a clinically validated remedy for SGAs-induced MetS, but its underlying mechanism remains unclear.

METHODS

A network pharmacology-based analysis was performed to explore predicted plasma-absorbed components, putative therapeutic targets, and main pathways involved in LGZGD bioactivity. We constructed a target interaction network between the predicted targets of LGZGD and the known targets of MetS, after which we extracted major hubs using topological analysis. Thereafter, the maximum value of "edge betweenness" of all interactions was defined as a bottleneck, which suggested its importance in connecting all targets in the network. Finally, a pathway enrichment analysis of major hubs was used to reveal the biological functions of LGZGD.

RESULTS

This approach identified 120 compounds and 361 candidate targets of LGZGD. According to the data generated in this study, the interaction between JUN and APOA1 plays a vital role in the treatment of SGAs-induced MetS using LGZGD. Interestingly, JUN was a putative target of LGZGD and APOA1 is one of the known targets of both MetS and SGAs (olanzapine and clozapine). LGZGD was significantly associated with several pathways including PI3K-Akt signaling, insulin resistance, and MAPK signaling pathway.

CONCLUSIONS

LGZGD might inhibit JUN and thereby increases the expression of APOA1 to maintain metabolic homeostasis via some vital pathways.

Multivariate analysis of genomics data to identify potential pleiotropic genes for type 2 diabetes, obesity and dyslipidemia using Meta-CCA and gene-based approach

Previous studies have demonstrated the genetic correlations between type 2 diabetes, obesity and dyslipidemia, and indicated that many genes have pleiotropic effects on them. However, these pleiotropic genes have not been well-defined. It is essential to identify pleiotropic genes using systematic approaches because systematically analyzing correlated traits is an effective way to enhance their statistical power. To identify potential pleiotropic genes for these three disorders, we performed a systematic analysis by incorporating GWAS (genome-wide associated study) datasets of six correlated traits related to type 2 diabetes, obesity and dyslipidemia using Meta-CCA (meta-analysis using canonical correlation analysis). Meta-CCA is an emerging method to systematically identify potential pleiotropic genes using GWAS summary statistics of multiple correlated traits. 2,720 genes were identified as significant genes after multiple testing (Bonferroni corrected p value < 0.05). Further, to refine the identified genes, we tested their relationship to the six correlated traits using VEGAS-2 (versatile gene-based association study-2). Only the genes significantly associated (Bonferroni corrected p value < 0.05) with more than one trait were kept. Finally, 25 genes (including two confirmed pleiotropic genes and eleven novel pleiotropic genes) were identified as potential pleiotropic genes. They were enriched in 5 pathways including the statin pathway and the PPAR (peroxisome proliferator-activated receptor) Alpha pathway. In summary, our study identified potential pleiotropic genes and pathways of type 2 diabetes, obesity and dyslipidemia, which may shed light on the common biological etiology and pathogenesis of these three disorders and provide promising insights for new therapies.

New insights into apolipoprotein A5 in controlling lipoprotein metabolism in obesity and the metabolic syndrome patients

Apolipoprotein A5 (apoA5) has been identified to play an important role in lipid metabolism, specifically in triglyceride (TG) and TG-rich lipoproteins (TRLs) metabolism. Numerous evidence has demonstrated for an association between apoA5 and the increased risk of obesity and metabolic syndrome, but the mechanism remains to be fully elucidated. Recently, several studies verified that apoA5 could significantly reduce plasma TG level by stimulating lipoprotein lipase (LPL) activity, and the intracellular role of apoA5 has also been proved since apoA5 is associated with cytoplasmic lipid droplets (LDs) and affects intrahepatic TG accumulation. Furthermore, since adipocytes provide the largest storage depot for TG and play a crucial role in the development of obesity, we could infer that apoA5 also acts as a novel regulator to modulate TG storage in adipocytes. In this review, we focus on the association of gene and protein of apoA5 with obesity and metabolic syndrome, and provide new insights into the physiological role of apoA5 in humans, giving a potential therapeutic target for obesity and associated disorders.

Interactions of six SNPs in APOA1 gene and types of obesity on low HDL-C disease in Xinjiang pastoral area of China

BACKGROUND

This study aims to investigate association between six single nucleotide polymorphisms(SNPs) in APOA1 gene and types of obesity with the risk of low level HDL-C in the pastoral area of northwest China.

METHODS

A total of 1267 individuals including 424 patients with low HDL-C disease and 843 health subjects were analyzed based on matched for age, sex. SNPShot technique was used to detect the genotypes of rs670, rs5069, rs5072, rs7116797, rs2070665 and rs1799837 in APOA1 gene. The relationship between above six SNPs and types of obesity with low HDL-C disease was analyzed by binary logistic regression.

RESULTS

Carriers with rs670 G allele were more likely to get low HDL-C disease (OR = 1.46, OR95%CI: 1.118-1.915; P = 0.005); The genotypic and allelic frequencies of rs5069, rs5072, rs7116797, rs2070665, rs1799837 revealed no significant differences between cases and controls (P < 0.05); with reference to normal weight, Waist circumference (WC), Waist-to-hip ratio (WHR) individuals, respectively, general obesity measured by BMI had 2.686 times (OR95%CI: 1.695-4.256; P < 0.01), abdominal obesity measured by WC had 1.925 times (OR95%CI: 1.273-2.910; P = 0.002) and abdominal obesity measured by WHR had 1.640 times (OR95%CI: 1.114-2.416; P = 0.012) risk to get low HDL-C disease; APOA1 rs670 interacted with obesity (no matter general obesity or abdominal obesity) on low HDL-C disease.

CONCLUSIONS

APOA1 gene may be associated with low HDL-C disease in the pastoral area of northwest China; obesity was the risk factor for low HDL-C disease; the low HDL-C disease is influenced by APOA1, obesity, and their interactions.

Gut microbiome in chronic kidney disease

NEW FINDINGS

What is the topic of this review? This review addresses the contribution of the altered gut microbiome to uraemic syndrome, with specific reference to gut microbiome-derived uraemic toxins. It also discusses the potential treatment options to normalize the disturbed microbiome in chronic kidney disease (CKD). What advances does it highlight? This review highlights the importance of the gut-kidney connection and how the altered microbial landscape in the intestine contributes to dysmetabolism and inflammation in CKD. Recent findings linking gut-derived uraemic toxins to progression of CKD, cardiovascular disease and mortality are also discussed. Finally, we briefly explain targeted therapies that have been studied to restore intestinal symbiosis in CKD. The human intestine is now recognized as an important metabolic organ powered by gut microbiota. This review addresses the alteration in the gut microbiome in patients with chronic kidney disease (CKD) and its consequence. We describe the major uraemic toxins, p-cresol sulfate, indoxyl sulfate and trimethylamine N-oxide, which are produced by the gut microbiome, and how these metabolites contribute to progression of CKD and associated cardiovascular disease. Translocation of endotoxin from the gut into the systemic circulation contributes to inflammation in CKD. Targeting the gut microbiome to restore symbiosis may prove to be a potent strategy in reducing inflammation and production of these uraemic toxins.

Triglyceride-raising APOA5 genetic variants are associated with obesity and non-HDL-C in Chinese children and adolescents

Background

Although the association between the apolipoprotein A5 (APOA5) genetic variants and hypertriglyceridemia has been extensively studied, there have been few studies, particularly in children and adolescents, on the association between APOA5 genetic variants and obesity or non-high-density lipoprotein cholesterol (non-HDL-C) levels. The objective of this study was to examine whether APOA5 gene polymorphisms affect body mass index (BMI) or plasma non-HDL-C levels in Chinese child population.

Methods

This was a case–control study. Single nucleotide polymorphisms (SNPs) were genotyped using Matrix-Assisted Laser Desorption/Ionization Time of Flight Mass Spectrometry for an association study in 569 obese or overweight and 194 healthy Chinese children and adolescents.

Results

Genotype distributions for all polymorphisms in both cohorts were in accordance with the Hardy-Weinberg distribution. The frequencies of the risk alleles in rs662799 and rs651821 SNPs in APOA5 gene were all increased in obese or overweight patients compared to the controls. After adjusted for age and sex, C carriers in rs662799 had a 1.496-fold [95% confidence interval (CI): 1.074-2.084, P = 0.017] higher risk for developing obesity or overweight than subjects with TT genotype, while C carriers in rs651821 had a 1.515-fold higher risk than subjects with TT genotype (95% CI: 1.088-2.100, P = 0.014). Triglyceride (TG) and non-HDL-C concentrations were significantly different among rs662799 variants and both were higher in carriers of minor allele than in noncarriers for TG (1.64 ± 0.96 vs. 1.33 ± 0.67 mmol/L) (P < 0.001), and for non-HDL-C (3.23 ± 0.92 vs. 3.02 ± 0.80 mmol/L) (P = 0.005), respectively. There was also a trend towards increased TG and non-high-density lipoprotein cholesterol levels for rs651821 C carriers (P < 0.001 and P = 0.002, respectively). Furthermore, to confirm the independence of the associations between APOA5 gene and TG or non-HDL-C levels, multiple linear regression analysis was performed and the relationships were not eliminated by adjustment for age, sex and BMI.

Conclusions

These findings suggest the TG-raising genetic variants in the APOA5 gene may influence the susceptibility of the individual to obesity, which may also contribute to an increased risk of high non-HDL-C levels in Chinese obese children and adolescents.

Apolipoprotein A5 deficiency aggravates high-fat diet-induced obesity due to impaired central regulation of food intake

Mutations in apolipoprotein A5 (APOA5) have been associated with hypertriglyceridemia in humans and mice. This has been attributed to a stimulating role for APOA5 in lipoprotein lipase-mediated triglyceride hydrolysis and hepatic clearance of lipoprotein remnant particles. However, because of the low APOA5 plasma abundance, we investigated an additional signaling role for APOA5 in high-fat diet (HFD)-induced obesity. Wild-type (WT) and Apoa5(-/-) mice fed a chow diet showed no difference in body weight or 24-h food intake (Apoa5(-/-), 4.5±0.6 g; WT, 4.2±0.5 g), while Apoa5(-/-) mice fed an HFD ate more in 24 h (Apoa5(-/-), 2.8±0.4 g; WT, 2.5±0.3 g, P<0.05) and became more obese than WT mice. Also, intravenous injection of APOA5-loaded VLDL-like particles lowered food intake (VLDL control, 0.26±0.04 g; VLDL+APOA5, 0.11±0.07 g, P<0.01). In addition, the HFD-induced hyperphagia of Apoa5(-/-) mice was prevented by adenovirus-mediated hepatic overexpression of APOA5. Finally, intracerebroventricular injection of APOA5 reduced food intake compared to injection of the same mouse with artificial cerebral spinal fluid (0.40±0.11 g; APOA5, 0.23±0.08 g, P<0.01). These data indicate that the increased HFD-induced obesity of Apoa5(-/-) mice as compared to WT mice is at least partly explained by hyperphagia and that APOA5 plays a role in the central regulation of food intake.

The paradox of ApoA5 modulation of triglycerides: evidence from clinical and basic research

Apolipoprotein A5 (ApoA5) is a key regulator of plasma triglycerides (TG), even though its plasma concentration is very low compared to other known apoproteins. Over the years, researchers have attempted to elucidate the molecular mechanisms by which ApoA5 regulates plasma TG in vivo. Though still under debate, two theories broadly describe how ApoA5 modulates TG levels: (i) ApoA5 enhances the catabolism of TG-rich lipoproteins and (ii) it inhibits the rate of production of very low-density lipoprotein (VLDL), the major carrier of TGs. This review will summarize the basic and clinical studies that describe the importance of ApoA5 in TG metabolism. Population studies conducted in various countries have demonstrated an association between single nucleotide polymorphisms (SNPs) in ApoA5 and the increased risk to cardiovascular disease and metabolic syndrome (including diabetes and obesity). ApoA5 is also highly expressed during liver regeneration and is an acute phase protein associated with HDL, which is independent of its effects on TG metabolism.

CONCLUSION

Despite considerable evidences available from clinical and basic research studies on the role of ApoA5 in TG metabolism and its indirect link to metabolic diseases, additional investigations are needed to understand the paradoxical role of this important apoprotein is modulated by both diet and its polymorphism variants.

Unravelling the effects of the environment and host genotype on the gut microbiome

To what extent do host genetics control the composition of the gut microbiome? Studies comparing the gut microbiota in human twins and across inbred mouse lines have yielded inconsistent answers to this question. However, candidate gene approaches, in which one gene is deleted or added to a model host organism, show that a single host gene can have a tremendous effect on the diversity and population structure of the gut microbiota. Now, quantitative genetics is emerging as a highly promising approach that can be used to better understand the overall architecture of host genetic influence on the microbiota, and to discover additional host genes controlling microbial diversity in the gut. In this Review, we describe how host genetics and the environment shape the microbiota, and how these three factors may interact in the context of chronic disease.