OBJECTIVE The liver is the key organ involved in systemic inflammation, but the relation between hepatic inflammation and atherogenesis is poorly understood. Since nuclear factor-κB (NF-κB) is a... Show moreOBJECTIVE The liver is the key organ involved in systemic inflammation, but the relation between hepatic inflammation and atherogenesis is poorly understood. Since nuclear factor-κB (NF-κB) is a central regulator of inflammatory processes, we hypothesized that chronically enhanced hepatic NF-κB activation, through hepatocyte-specific expression of IκB kinase-β (IKKβ) (LIKK), will aggravate atherosclerosis development in APOE*3-Leiden (E3L) mice. METHODS AND RESULTS E3L.LIKK and E3L control littermates were fed a Western-type diet for 24 weeks. E3L.LIKK mice showed a 2.3-fold increased atherosclerotic lesion area and more advanced atherosclerosis in the aortic root with less segments without atherosclerotic lesions (11% vs. 42%), and more segments with mild (63% vs. 44%) and severe (26% vs. 14%) lesions. Expression of LIKK did not affect basal levels of inflammatory parameters, but plasma cytokine levels tended to be higher in E3L.LIKK mice after lipopolysaccharide (LPS) administration. E3L.LIKK mice showed transiently increased plasma cholesterol levels, confined to (V)LDL. This transient character resulted in a mild (+17%) increased cumulative plasma cholesterol exposure. CONCLUSION We conclude that selective activation of NF-κB in hepatocytes considerably promotes atherosclerosis development which is (at least partly) explained by an increased sensitivity to proinflammatory triggers and transiently increased plasma cholesterol levels. Show less
Low-grade inflammation in different tissues, including activation of the nuclear factor kappa B pathway in liver, is involved in metabolic disorders such as type 2 diabetes and cardiovascular... Show moreLow-grade inflammation in different tissues, including activation of the nuclear factor kappa B pathway in liver, is involved in metabolic disorders such as type 2 diabetes and cardiovascular diseases (CVDs). In this study, we investigated the relation between chronic hepatocyte-specific overexpression of IkB kinase (IKK)-beta and hypertriglyceridemia, an important risk factor for CVD, by evaluating whether activation of IKK-beta only in the hepatocyte affects VLDL-triglyceride (TG) metabolism directly. Transgenic overexpression of constitutively active human IKK-beta specifically in hepatocytes of hyperlipidemic APOE*3-Leiden mice clearly induced hypertriglyceridemia. Mechanistic in vivo studies revealed that the hypertriglyceridemia was caused by increased hepatic VLDL-TG production rather than a change in plasma VLDL-TG clearance. Studies in primary hepatocytes showed that IKK-beta overexpression also enhances TG secretion in vitro, indicating a direct relation between IKK-beta activation and TG production within the hepatocyte. Hepatic lipid analysis and hepatic gene expression analysis of pathways involved in lipid metabolism suggested that hepatocyte- specific IKK-beta overexpression increases VLDL production not by increased steatosis or decreased FA oxidation, but most likely by carbohydrate-responsive element binding protein-mediated upregulation of Fas expression.jlr These findings implicate that specific activation of inflammatory pathways exclusively within hepatocytes induces hypertriglyceridemia. Furthermore, we identify the hepatocytic IKK-beta pathway as a possible target to treat hypertriglyceridemia. van Diepen, J. A., M. C. Wong, B. Guigas, J. Bos, R. Stienstra, L. Hodson, S. E. Shoelson, J. F. P. Berbee, P. C. N. Rensen, J. A. Romijn, L. M. Havekes, and P. J. Voshol. Hepatocyte-specific IKK-beta activation enhances VLDL-triglyceride production in APOE*3-Leiden mice. J. Lipid Res. 2011. 52: 942-950. Show less
Low-grade inflammation in different tissues, including activation of the nuclear factor κB (NF-κB) pathway in liver, is involved in metabolic disorders such as type 2 diabetes and cardiovascular... Show moreLow-grade inflammation in different tissues, including activation of the nuclear factor κB (NF-κB) pathway in liver, is involved in metabolic disorders such as type 2 diabetes and cardiovascular diseases (CVD). In this study we investigated the relation between chronic hepatocyte-specific overexpression of IKK-β and hypertriglyceridemia, an important risk factor for CVD, by evaluating whether activation of IKK-β only in the hepatocyte affects VLDL-triglyceride (TG) metabolism directly. Transgenic overexpression of constitutively active human IκB kinase (IKK-β) specifically in hepatocytes of hyperlipidemic APOE*3-Leiden mice clearly induced hypertriglyceridemia. Mechanistic in vivo studies revealed that the hypertriglyceridemia was caused by increased hepatic VLDL-TG production, rather than a change in plasma VLDL-TG clearance. Studies in primary hepatocytes showed that IKK-β overexpression also enhances TG secretion in vitro, indicating a direct relation between IKK-β activation and TG production within the hepatocyte. Hepatic lipid analysis and hepatic gene expression analysis of pathways involved in lipid metabolism suggested that hepatocyte specific IKK-β overexpression increases VLDL production not by increased steatosis or decreased FA oxidation, but most likely by ChREBP-mediated upregulation of Fas expression. These findings implicate that specific activation of inflammatory pathways exclusively within hepatocytes induces hypertriglyceridemia. Furthermore, we identify the hepatocytic IKK-β pathway as a possible target to treat hypertriglyceridemia. Show less
