Background and aims: Combined agonism of the glucose-dependent insulinotropic polypeptide receptor (GIPR) and the glucagon-like peptide-1 receptor (GLP1R) is superior to single GLP1R agonism in... Show moreBackground and aims: Combined agonism of the glucose-dependent insulinotropic polypeptide receptor (GIPR) and the glucagon-like peptide-1 receptor (GLP1R) is superior to single GLP1R agonism in terms of glycemic control and lowering body weight in individuals with obesity and with or without type 2 diabetes mellitus. As both GIPR and GLP1R signaling have also been implicated in improving inflammatory responses and lipid handling, two crucial players in atherosclerosis development, here we aimed to investigate the effects of combined GIPR/GLP1R agonism in APOE*3-Leiden.CETP mice, a well-established mouse model for human-like lipoprotein metabolism and atherosclerosis development. Methods: Female APOE*3-Leiden.CETP mice were fed a Western-type diet (containing 16% fat and 0.15% cholesterol) to induce dyslipidemia, and received subcutaneous injections with either vehicle, a GIPR agonist (GIPFA-085), a GLP1R agonist (GLP-140) or both agonists. In the aortic root area, atherosclerosis development was assessed. Results: Combined GIPR/GLP1R agonism attenuated the development of severe atherosclerotic lesions, while single treatments only showed non-significant improvements. Mechanistically, combined GIPR/GLP1R agonism decreased markers of systemic low-grade inflammation. In addition, combined GIPR/GLP1R agonism markedly lowered plasma triglyceride (TG) levels as explained by reduced hepatic very-low-density lipoprotein (VLDL)-TG production as well as increased TG-derived fatty acid uptake by brown and white adipose tissue which was coupled to enhanced hepatic uptake of core VLDL remnants. Conclusions: Combined GIPR/GLP1R agonism attenuates atherosclerosis severity by diminishing inflammation and increasing VLDL turnover. We anticipate that combined GIPR/GLP1R agonism is a promising strategy to lower cardiometabolic risk in humans. Show less
Brown adipocytes within brown adipose tissue (BAT) and beige adipocytes within white adipose tissue dissipate nutritional energy as heat. Studies in mice have shown that activation of thermogenesis... Show moreBrown adipocytes within brown adipose tissue (BAT) and beige adipocytes within white adipose tissue dissipate nutritional energy as heat. Studies in mice have shown that activation of thermogenesis in brown and beige adipocytes enhances the lipolytic processing of triglyceride-rich lipoproteins (TRLs) in plasma to supply these adipocytes with fatty acids for oxidation. This process results in formation of TRL remnants that are removed from the circulation through binding of apolipoprotein E (ApoE) on their surface to the LDL receptor (LDLR) on hepatocytes, followed by internalization. Concomitantly, lipolytic processing of circulating TRLs leads to generation of excess surface phospholipids that are transferred to nascent HDLs, increasing their capacity for reverse cholesterol transport. Activation of thermogenic adipocytes thus lowers circulating triglycerides and non-HDL-cholesterol, while it increases HDL-cholesterol. The combined effect is protection from atherosclerosis development, which becomes evident in humanized mouse models with an intact ApoE-LDLR clearance pathway only, and is additive to the effects of classical lipid-lowering drugs including statins and proprotein convertase subtilisin/kexin type 9 inhibitors. A large recent study revealed that the presence of metabolically active BAT in humans is associated with lower triglycerides, higher HDL-cholesterol and lower risk of cardiovascular diseases. This narrative review aims to provide leads for further exploration of thermogenic adipose tissue as a therapeutic target. To this end, we describe the latest knowledge on the role of BAT in lipoprotein metabolism and address, for example, the discovery of the beta(2)-adrenergic receptor as the dominant adrenergic receptor in human thermogenic adipocytes. Show less
Proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibition, by increasing hepatic low density lipoprotein (LDL) receptor (LDLR) levels, has emerged as a strategy to reduce atherosclerosis by... Show moreProprotein convertase subtilisin/kexin type 9 (PCSK9) inhibition, by increasing hepatic low density lipoprotein (LDL) receptor (LDLR) levels, has emerged as a strategy to reduce atherosclerosis by lowering circulating very low density lipoprotein (VLDL)-cholesterol. We hypothesized that the therapeutic effectiveness of PCSK9 inhibition can be increased by accelerating the generation of VLDL remnants, which typically have a high affinity for the LDLR. Therefore, we aimed to investigate whether accelerating lipolytic processing of VLDL by brown fat activation can further lower (V)LDL and reduce atherosclerosis on top of PCSK9 inhibition. APOE*3-Leiden.CETP mice were fed a Western-type diet and treated with the anti-PCSK9 antibody alirocumab or saline. After 2 weeks, both groups of mice were randomized to receive either the selective beta 3-adrenergic receptor (AR) agonist CL316,243 to activate brown fat or saline for 3 additional weeks to evaluate VLDL clearance or 12 additional weeks to analyze atherosclerosis development. beta 3-AR agonism and alirocumab combined decreased (V)LDL-cholesterol compared to alirocumab alone, which was explained by an accelerated plasma clearance of VLDL-cholesteryl esters that were mainly taken up by the liver. In addition, the combination promoted the transfer of VLDL-phospholipids to HDL to a higher extent than alirocumab alone, accompanied by higher plasma HDL-cholesterol levels and increased cholesterol efflux capacity. Consequently, combination treatment largely reduced atherosclerotic lesion area compared to vehicle. Together, beta 3-AR agonism enhances the lipoprotein-modulating effects of alirocumab to further improve dyslipidemia and non-significantly further attenuate atherosclerosis development. Our findings demonstrate that brown fat activation may enhance the therapeutic effects of PCSK9 inhibition in dyslipidemia. Show less
