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Background and Purpose The aetiology of inflammation in the liver and vessel wall, leading to non‐alcoholic steatohepatitis (NASH) and atherosclerosis, respectively, shares common mechanisms including macrophage infiltration. To treat both disorders simultaneously, it is highly important to tackle the inflammatory status. Exendin‐4, a glucagon‐like peptide‐1 (GLP‐1) receptor agonist, reduces hepatic steatosis and has been suggested to reduce atherosclerosis; however, its effects on liver inflammation are underexplored. Here, we tested the hypothesis that exendin‐4 reduces inflammation in both the liver and vessel wall, and investigated the common underlying mechanism. Experimental Approach Female APOE*3‐Leiden.CETP mice, a model with human‐like lipoprotein metabolism, were fed a cholesterol‐containing Western‐type diet for 5 weeks to induce atherosclerosis and subsequently treated for 4 weeks with exendin‐4. Key Results Exendin‐4 modestly improved dyslipidaemia, but markedly decreased atherosclerotic lesion severity and area (−33%), accompanied by a reduction in monocyte adhesion to the vessel wall (−42%) and macrophage content in the plaque (−44%). Furthermore, exendin‐4 reduced hepatic lipid content and inflammation as well as hepatic CD68+ (−18%) and F4/80+ (−25%) macrophage content. This was accompanied by less monocyte recruitment from the circulation as the Mac‐1+ macrophage content was decreased (−36%). Finally, exendin‐4 reduced hepatic chemokine expression in vivo and suppressed oxidized low‐density lipoprotein accumulation in peritoneal macrophages in vitro, effects dependent on the GLP‐1 receptor. Conclusions and Implications Exendin‐4 reduces inflammation in both the liver and vessel wall by reducing macrophage recruitment and activation. These data suggest that exendin‐4 could be a valuable strategy to treat NASH and atherosclerosis simultaneously.

The present study is the first intervention study in a well-established, translational mouse model for hyperlipidaemia and atherosclerosis showing that anacetrapib dose-dependently reduces atherosclerosis development and adds to the anti-atherogenic effects of atorvastatin. This effect is mainly ascribed to the reduction in non-HDL-C despite a remarkable increase in HDL-C and without affecting HDL functionality. In addition, anacetrapib improves lesion stability.

High plasma levels of (V)LDL cholesterol [(V)LDL-C] and TGs, as well as low levels of HDL cholesterol (HDL-C), are important risk factors for cardiovascular diseases. The standard treatment for the reduction of cardiovascular disease risk is statin therapy aiming to reduce plasma (V) LDL-C. However, a substantial residual risk remains despite statin treatment. This has prompted the search for secondary treatment targets ( 1, 2 ). Prospective epidemiological studies indicate HDL-C as a potential target ( 3 ). The ratio of plasma (V)LDL-C to HDL-C is to a great extent affected by cholesteryl ester transfer protein (CETP). CETP facilitates the transfer of cholesteryl esters from HDL to (V)LDL in exchange for TG ( 4 ). In several mouse Abstract Recently, we showed in APOE*3-Leiden cholesteryl ester transfer protein (E3L.CETP) mice that anacetrapib attenuated atherosclerosis development by reducing (V) LDL cholesterol [(V)LDL-C] rather than by raising HDL cholesterol. Here, we investigated the mechanism by which anacetrapib reduces (V)LDL-C and whether this effect was dependent on the inhibition of CETP. E3L.CETP mice were fed a Western-type diet alone or supplemented with anacetrapib (30 mg/kg body weight per day). Microarray analyses of livers revealed downregulation of the cholesterol biosynthesis pathway ( P < 0.001) and predicted downregulation of pathways controlled by sterol regulatory element-binding proteins 1 and 2 ( z -scores ؊ 2.56 and ؊ 2.90, respectively; both P < 0.001). These data suggest increased supply of cholesterol to the liver. We found that hepatic proprotein convertase subtilisin/kexin type 9 ( Pcsk9 ) expression was decreased ( ؊ 28%, P < 0.01), accompanied by decreased plasma PCSK9 levels ( ؊ 47%, P < 0.001) and increased hepatic LDL receptor (LDLr) content (+64%, P < 0.01). Consistent with this, anacetrapib increased the clearance and hepatic uptake (+25%, P < 0.001) of [ 14 C]cholesteryl oleatelabeled VLDL-mimicking particles. In E3L mice that do not express CETP, anacetrapib still decreased (V)LDL-C and plasma PCSK9 levels, indicating that these effects were independent of CETP inhibition. We conclude that anacetrapib reduces (V)LDL-C by two mechanisms: 1 ) inhibition of CETP activity, resulting in remodeled VLDL particles that are more susceptible to hepatic uptake; and 2 ) a CETPindependent reduction of plasma PCSK9 levels that has the potential to increase LDLr-mediated hepatic remnant

BackgroundLipopolysaccharide (LPS) decreases hepatic CETP (cholesteryl ester transfer protein) expression albeit that the underlying mechanism is disputed. We recently showed that plasma CETP is mainly derived from Kupffer cells (KCs). In this study, we investigated the role of KC subsets in the mechanism by which LPS reduces CETP expression.Methods and ResultsIn CETP‐transgenic mice, LPS markedly decreased hepatic CETP expression and plasma CETP concentration without affecting hepatic macrophage number. This was paralleled by decreased expression of the resting KC markers C‐type lectin domain family 4, member f (Clec4f) and V‐set and immunoglobulin domain containing 4 (Vsig4), while expression of the infiltrating monocyte marker lymphocyte antigen 6 complex locus C (Ly6C) was increased. Simultaneously, the ratio of plasma high‐density lipoprotein‐cholesterol over non–high‐density lipoprotein‐cholesterol transiently increased. After ablation hepatic macrophages via injection with liposomal clodronate, the reappearance of hepatic gene and protein expression of CETP coincided with Clec4f and Vsig4, but not Ly6C. Double‐immunofluorescence staining showed that CETP co‐localized with Clec4f+ KCs and not Ly6C+ monocytes. In humans, microarray gene‐expression analysis of liver biopsies revealed that hepatic expression and plasma level of CETP both correlated with hepatic VSIG4 expression. LPS administration decreased the plasma CETP concentration in humans. In vitro experiments showed that LPS reduced liver X receptor‐mediated CETP expression.ConclusionsHepatic expression of CETP is exclusively confined to the resting KC subset (ie, F4/80+Clec4f+Vsig4+Ly6C−). LPS activated resting KCs, leading to reduction of Clec4f and Vsig4 expression and reduction of hepatic CETP expression, consequently decreasing plasma CETP and raising high‐density lipoprotein (HDL)‐cholesterol. This sequence of events is consistent with the anti‐inflammatory role of HDL in the response to LPS and may be relevant as a defense mechanism against bacterial infections.