Fenofibrate reverses the decline in HDL cholesterol in mice overexpressing human phospholipid transfer protein

Development of abdominal aortic aneurysm is decreased in mice with plasma phospholipid transfer protein deficiency

Plasma phospholipid transfer protein (PLTP) increases the circulating levels of proatherogenic lipoproteins, accelerates blood coagulation, and modulates inflammation. The role of PLTP in the development of abdominal aortic aneurysm (AAA) was investigated by using either a combination of mechanical and elastase injury at one site of mouse aorta (elastase model) or continuous infusion of angiotensin II in hyperlipidemic ApoE-knockout mice (Ang II model). With the elastase model, complete PLTP deficiency was associated with a significantly lower incidence and a lesser degree of AAA expansion. With the Ang II model, findings were consistent with those in the elastase model, with a lower severity grade in PLTP-deficient mice, an intermediate phenotype in PLTP-deficient heterozygotes, and a blunted effect of the PLTP-deficient trait when restricted to bone marrow-derived immune cells. The protective effect of whole-body PLTP deficiency in AAA was illustrated further by a lesser degree of adventitia expansion, reduced elastin degradation, fewer recruited macrophages, and less smooth muscle cell depletion in PLTP-deficient than in wild-type mice, as evident from comparative microscopic analysis of aorta sections. Finally, cumulative evidence supports the association of PLTP deficiency with reduced expression and activity levels of matrix metalloproteinases, known to degrade elastin and collagen. We conclude that PLTP can play a significant role in the pathophysiology of AAA.

The thienotriazolodiazepine Ro 11-1464 increases plasma apoA-I and promotes reverse cholesterol transport in human apoA-I transgenic mice

BACKGROUND AND PURPOSE

Ro 11-1464 is a thienotriazolodiazepine previously described to selectively stimulate apolipoprotein A-I (apoA-I) production and mRNA level in human liver cells. Here, we studied its effects upon oral administration to human apoA-I transgenic (hapoA-I) mice.

EXPERIMENTAL APPROACH

HapoA-I mice were treated for 5 days with increasing doses of Ro 11-1464. Macrophage reverse cholesterol transport (mph-RCT) was assessed by following [(3) H]-cholesterol mobilization from pre-labelled i.p. injected J774 macrophages to plasma, liver and faeces. Effects on plasma lipids, apoproteins, lecithin-cholesterol : acyltransferase (LCAT) and liver enzymes, as well as on faecal excretion of cholesterol and bile salts, and on liver lipids and mRNA contents were determined.

KEY RESULTS

Treatment with Ro 11-1464 300 mg·kg(-1) ·day(-1) resulted in a nearly 2-fold increase in plasma apoA-I, a 2- to 3-fold increase in the level of large sized-pre-β high-density lipoprotein and a 3-fold selective up-regulation of hepatic apoA-I mRNA, but a marked decrease in all plasma lipids and LCAT activity. Mpm-RCT was decreased in blood but markedly increased in faecal sterols (4-fold) and bile acids (1.7-fold). However, liver weight and liver enzymes in plasma were also increased, in parallel with an increase in liver cholesterol ester content (all these effect being significant).

CONCLUSION AND IMPLICATIONS

In this model Ro 11-1464 causes increased hepatic expression and plasma levels of apoA-I and a suppression of LCAT, and a marked enhancement of reverse cholesterol transport, but also some symptoms of liver toxicity. The compound may therefore be a prototype for a next generation of anti-atherosclerotic medicines.

Comparative transcriptomic and metabolomic analysis of fenofibrate and fish oil treatments in mice

Elevated circulating triglycerides, which are considered a risk factor for cardiovascular disease, can be targeted by treatment with fenofibrate or fish oil. To gain insight into underlying mechanisms, we carried out a comparative transcriptomics and metabolomics analysis of the effect of 2 wk treatment with fenofibrate and fish oil in mice. Plasma triglycerides were significantly decreased by fenofibrate (−49.1%) and fish oil (−21.8%), whereas plasma cholesterol was increased by fenofibrate (+29.9%) and decreased by fish oil (−32.8%). Levels of various phospholipid species were specifically decreased by fish oil, while levels of Krebs cycle intermediates were increased specifically by fenofibrate. Plasma levels of many amino acids were altered by fenofibrate and to a lesser extent by fish oil. Both fenofibrate and fish oil upregulated genes involved in fatty acid metabolism and downregulated genes involved in blood coagulation and fibrinolysis. Significant overlap in gene regulation by fenofibrate and fish oil was observed, reflecting their property as high or low affinity agonist for peroxisome proliferator-activated receptor-α, respectively. Fenofibrate specifically downregulated genes involved in complement cascade and inflammatory response. Fish oil specifically downregulated genes involved in cholesterol and fatty acid biosynthesis and upregulated genes involved in amino acid and arachidonic acid metabolism. Taken together, the data indicate that despite being similarly potent toward modulating plasma free fatty acids, cholesterol, and triglyceride levels, fish oil causes modest changes in gene expression likely via activation of multiple mechanistic pathways, whereas fenofibrate causes pronounced gene expression changes via a single pathway, reflecting the key difference between nutritional and pharmacological intervention.

Hyperlipidemia: a new therapeutic target for diabetic neuropathy

Emerging data establish dyslipidemia as a significant contributor to the development of diabetic neuropathy. In this review, we discuss how separate metabolic imbalances, including hyperglycemia and hyperlipidemia, converge on mechanisms leading to oxidative stress in dorsal root ganglia (DRG) sensory neurons. We conclude with suggestions for novel therapeutic strategies to prevent or reverse diabetes-induced nerve degeneration.

Fibrates: where are we now?

Cardiovascular disease remains a leading cause of mortality worldwide. As dyslipidemia increases cardiovascular disease risk, proper management of dyslipidemia is one means by which to decrease cardiovascular disease risk. This review focuses on dyslipidemia treatment utilizing fibrate therapy, which targets high trigylcerides, low HDL, and high small, dense LDL, while contrasting fibrate therapy with statin therapy and combined therapy. Studies were obtained using electronic search strategies, such as Medline and Cochrane Library. Sources selected were limited to those that discussed fibrates, statins, and combined therapy, with specific emphasis placed on sources that focused on fibrates. Selected studies were then assessed for quality via analysis of the study's methodology, results, and data.

RESULTS

of selected studies were then stratified using a rating system devised to determine the quality of results using the scientific evidence provided for them. Combination fibrate and statin therapy can be more effective in achieving optimal lipid levels than just fibrate or statin therapy alone without significant side effects as long as gemfibrozil is not used in therapy.

Fenofibrate increases HDL-cholesterol by reducing cholesteryl ester transfer protein expression

In addition to efficiently decreasing VLDL-triglycerides (TGs), fenofibrate increases HDL-cholesterol levels in humans. We investigated whether the fenofibrate-induced increase in HDL-cholesterol is dependent on the expression of the cholesteryl ester transfer protein (CETP). To this end, APOE*3-Leiden (E3L) transgenic mice without and with the human CETP transgene, under the control of its natural regulatory flanking regions, were fed a Western-type diet with or without fenofibrate. Fenofibrate (0.04% in the diet) decreased plasma TG in E3L and E3L.CETP mice (-59% and -60%; P < 0.001), caused by a strong reduction in VLDL. Whereas fenofibrate did not affect HDL-cholesterol in E3L mice, fenofibrate dose-dependently increased HDL-cholesterol in E3L.CETP mice (up to +91%). Fenofibrate did not affect the turnover of HDL-cholesteryl ester (CE), indicating that fenofibrate causes a higher steady-state HDL-cholesterol level without altering the HDL-cholesterol flux through plasma. Analysis of the hepatic gene expression profile showed that fenofibrate did not differentially affect the main players in HDL metabolism in E3L.CETP mice compared with E3L mice. However, in E3L.CETP mice, fenofibrate reduced hepatic CETP mRNA (-72%; P < 0.01) as well as the CE transfer activity in plasma (-73%; P < 0.01). We conclude that fenofibrate increases HDL-cholesterol by reducing the CETP-dependent transfer of cholesterol from HDL to (V)LDL, as related to lower hepatic CETP expression and a reduced plasma (V)LDL pool.