The studies described in this thesis show that inflammation and CETP are both important factors in lipid metabolism and atherosclerosis. In the first part of this thesis we showed that high dietary... Show moreThe studies described in this thesis show that inflammation and CETP are both important factors in lipid metabolism and atherosclerosis. In the first part of this thesis we showed that high dietary cholesterol can induce hepatic inflammation via disturbed cholesterol homeostasis and ER stress, revealing new targets for the treatment of metabolic inflammation. Next, we demonstrated that intervention in both systemic and vascular inflammation can reduce atherosclerosis progression and/ or induce regression, highlighting the importance of developing drugs targeting the inflammatory component of atherosclerotic disease. In the second part of this thesis we showed that CETP inhibition per se may be anti-atherogenic, but that combination therapy of the CETP inhibitor torcetrapib with atorvastatin may have obscured its atheroprotective effect. Furthermore, we showed that the VLDL-increasing effect of CETP largely explains its atherogenic effect, at least in APOE*3-Leiden.CETP mice, and that CETP inhibition may negatively affect lesion stability. Our data suggest that CETP inhibition may not be the most optimal strategy to increase HDL-C levels and thereby reduce atherosclerosis. We anticipate that strategies improving HDL functionality, rather than raising the HDL level, are more likely to effectively reduce CVD. Show less
The research described in this thesis focussed on the role of apolipoproteins in lipid metabolism, inflammation and bacterial sepsis, with specific emphasis on apoCI. From studies in human APOC1_... Show moreThe research described in this thesis focussed on the role of apolipoproteins in lipid metabolism, inflammation and bacterial sepsis, with specific emphasis on apoCI. From studies in human APOC1_-transgenic and apoc1-/- mice, we were able to identify apoCI as a potent inhibitor of triglyceride hydrolysis by inhibiting lipoprotein lipase. Since APOC1 mice have thus increased VLDL levels, and VLDL protects against bacterial infection, we studied whether apoCI could play a role in inflammation and infection. We found that apoCI was able to bind lipopolysaccharide (LPS), the main toxic component of Gram-negative bacteria. Interestingly, although other apolipoproteins which have been studied have anti-inflammatory properties, we found that apoCI is a pro-inflammatory protein. By enhancing the biological response towards LPS and Gram-negative bacteria, apoCI dose-dependently improved the anti-bacterial attack, and protected against intrapulmonal Klebsiella pneumoniae-induced sepsis. Consistent with these experimental findings we also found that subjects with high plasma apoCI levels were less prone to infection-related mortality during follow-up, independent of plasma lipid levels. Likewise, survivors of severe sepsis showed higher plasma apoCI levels as compared to non-survivors, again independent of lipid levels. Taken together, our findings indicate that apoCI is an important determinant of the inflammatory response in mice and humans. Show less
