Resistance to obesity and resistance to atherosclerosis: is there a metabolic link?

Genetic Variants Associated with Supernormal Coronary Arteries

AIMS

Genetic and medical insights from studies on cardioprotective phenotypes aid the development of novel therapeutics. This study identified genetic variants associated with supernormal coronary arteries using genome-wide association study data and the corresponding genes based on expression quantitative trait loci (eQTL).

METHODS

Study participants were selected from two Korean cohorts according to inclusion criteria that included males with high cardiovascular risk (Framingham risk score ≥ 14, 10-year risk ≥ 16%) but with normal coronary arteries (supernormal group) or coronary artery disease (control group). After screening 12,309 individuals, males meeting the supernormal phenotype (n=72) and age-matched controls (n=94) were enrolled. Genetic variants associated with the supernormal phenotype were identified using Firth's logistic regression, and eQTL was used to evaluate whether the identified variants influence the expression of particular genes in human tissues.

RESULTS

Approximately 5 million autosomal variants were tested for association with the supernormal phenotype, and 10 independent loci suggestive of supernormal coronary arteries (p＜5.0 ×10 ^－5) were identified. The lead variants were seven intergenic single-nucleotide polymorphisms (SNPs), including one near PBX1, and three intronic SNPs, including one in PPFIA4. Of these variants or their proxies, rs9630089, rs6427989, and rs4984694 were associated with expression levels of SLIT1 and ARHGAP19, PPFIA4, and METTL26 in human tissues, respectively. These eQTL results supported their potential biological relevance.

CONCLUSIONS

This study identified genetic variants and eQTL genes associated with supernormal coronary arteries. These results suggest candidate genes representing potential therapeutic targets for coronary artery disease.

High fat high sucrose diet-induced dyslipidemia in guinea pigs

Easy access to high-calorie and fat-dense fast food has resulted in unhealthy dietary and lifestyle changes worldwide, which affects both developed and developing economies. This predisposes populations to a considerable number of metabolic and inflammatory conditions, such as diabetes, nonalcoholic fatty liver disease (NAFLD), and cardiovascular disease (CVD). Guinea pigs have been proposed as a model to study high-fat diet-induced metabolic disease due to their similar antioxidant metabolism and lipid profile to humans, and their susceptibility to atherosclerosis and endothelial disease. This study aims to evaluate cardiovascular and metabolic disorders induced by high-fat high-sucrose diet (HFHSD) in guinea pigs. Two to three-week-old male guinea pigs were fed a normal diet (ND) or HFHSD for 12 wk. Guinea pigs fed a HFHSD developed glucose intolerance, dyslipidemia, and liver, cardiac, and kidney damage. However, hypertension, dysautonomia, endothelial disease, and obesity were absent in these HFHSD guinea pigs. Taken together, these results show that guinea pigs fed a HFHSD are a nonobese model of metabolic disorders, resulting in important cardiac damage. Moreover, our findings suggest that NAFLD may be an important risk factor for diet-induced CVD.NEW & NOTEWORTHY In this study, we show a new animal model for diet-induced disease metabolic disorders without obesity in guinea pigs. Moreover, results suggest a strong relation between liver disease and increased cardiovascular risks.

Leptin upregulates caveolin-1 expression: implications for development of atherosclerosis

OBJECTIVE

To determine the role of hyperleptinemia on caveolin-1 expression and leptin signaling.

METHODS

Endothelial cells are critical to atherosclerosis development; therefore we investigated hyperleptinemia in cultured vascular endothelial cells. Dose-dependent effect of leptin on caveolin-1 expression was determined by Western blot analysis. Also, the consequence of increased caveolin-1 expression on leptin signaling was investigated by adenovirus mediated caveolin-1 overexpression. The effect of increased caveolin-1 expression on leptin-dependent activation of ERK1/2 and eNOS was determined by Western blot analysis.

RESULTS

Leptin upregulates caveolin-1 protein expression in a dose dependent manner and increased caveolin-1 expression impairs leptin signaling.

CONCLUSIONS

Leptin increases caveolin-1 protein expression which impairs leptin signaling in vascular endothelial cells. Our study identifies an additional leptin mediated proatherogenic mechanism and a novel caveolin-1 dependent leptin feedback mechanism which may have implications for development of peripheral leptin resistance in the endothelium.

Leptin upregulates caveolin-1 expression: implications for development of atherosclerosis

OBJECTIVE

To determine the role of hyperleptinemia on caveolin-1 expression and leptin signaling.

METHODS

Endothelial cells are critical to atherosclerosis development; therefore we investigated hyperleptinemia in cultured vascular endothelial cells. Dose-dependent effect of leptin on caveolin-1 expression was determined by Western blot analysis. Also, the consequence of increased caveolin-1 expression on leptin signaling was investigated by adenovirus mediated caveolin-1 overexpression. The effect of increased caveolin-1 expression on leptin-dependent activation of ERK1/2 and eNOS was determined by Western blot analysis.

RESULTS

Leptin upregulates caveolin-1 protein expression in a dose dependent manner and increased caveolin-1 expression impairs leptin signaling.

CONCLUSIONS

Leptin increases caveolin-1 protein expression which impairs leptin signaling in vascular endothelial cells. Our study identifies an additional leptin mediated proatherogenic mechanism and a novel caveolin-1 dependent leptin feedback mechanism which may have implications for development of peripheral leptin resistance in the endothelium.