leukotriene-b4 and Hyperlipidemias

High postprandial serum lipid concentrations are associated with increased oxidative stress which, in turn, increases the risk of atherosclerosis. Epidemiological studies correlate lower incidence of cardiovascular disease with adherence to the Mediterranean diet. The aim of this study was to evaluate changes in inflammatory (TXB(2) and LTB(4)) and oxidative stress markers (urinary hydrogen peroxide levels and serum antioxidant capacity), in addition to classic lipid parameters, after a fat-rich meal administered to 12 normolipemic, healthy subjects. Following a Latin square design, subjects were divided into three groups, each one receiving a different kind of oil (extra virgin olive oil; EVOO, olive oil; OO or corn oil; CO, together with 150g of potatoes), with 2-week washout periods between treatments. Blood samples were drawn at baseline and after 1, 2, and 6h after the meal. A significant decrease in inflammatory markers, namely TXB(2) and LTB(4), after 2 and 6h after EVOO (but not OO or CO) consumption and a concomitant increase of serum antioxidant capacity were recorded. These data reinforce the notion that the Mediterranean diet reduces the incidence of coronary heart disease partially due to the protective role of its phenolic components, including those of extra virgin olive oil.

Topics: Adult; Antioxidants; Blood Glucose; Cardiotonic Agents; Cholesterol, HDL; Cholesterol, LDL; Corn Oil; Coronary Disease; Diet, Mediterranean; Dietary Fats, Unsaturated; Flavonoids; Humans; Hyperlipidemias; Inflammation; Leukotriene B4; Male; Olive Oil; Oxidative Stress; Phenols; Plant Oils; Polyphenols; Postprandial Period; Thromboxane B2; Triglycerides

Serum levels of leukotriene-B4 (LTB4) are increased in type 1 diabetes (T1D) and it mediates systemic inflammation and macrophage reprogramming associated with this condition. Herein, we investigated the involvement of LTB4 in adiposity loss, hyperlipidemia, and changes in macrophage metabolism in a mouse model of streptozotocin-induced T1D. LTB4 receptor (BLT1) antagonist u75302 was employed to block LTB4 effects. As expected, hypoinsulinemia in T1D was associated with hyperglycemia, low levels of glucagon, hyperlipidemia, significant body fat loss, and increased white adipose tissue expression of Fgf21, a marker for lipolysis. With the exception of hyperglycemia and hypoglucagonemia, blockade of LTB4 signaling reverted these parameters in T1D mice. Along with hyperlipidemia, macrophages from T1D mice exhibited higher lipid uptake and accumulation. These cells also had enhanced glycolysis and oxidative metabolism and these parameters were dependent on the mitochondrial uncoupling respiration, as evidenced by elevated expression of oxidation markers carnitine palmitoyltransferase and uncoupling protein 1. Interestingly, all these parameters were at least partially reverted in T1D mice treated with u75302. Altogether, these findings suggest that in T1D mice LTB4/BLT1 is involved in the fat loss, hyperlipidemia, and increased macrophage lipid uptake and metabolism with an important involvement of mitochondrial uncoupling activity. These previously unrecognized LTB4/BLT1 functions may be explored in future to therapeutically alleviate severity of hyperlipidemia and systemic inflammation in T1D.

Topics: Adiposity; Animals; Biomarkers; Diabetes Mellitus, Type 1; Down-Regulation; Energy Metabolism; Fatty Acids; Glycolysis; Hyperlipidemias; Leukotriene B4; Lipogenesis; Liver; Macrophages, Peritoneal; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Oxidation-Reduction; Signal Transduction; Uncoupling Protein 1

Cyclooxygenase (COX) and 5-lipoxygenase (5-LOX), which play pivotal roles in atherogenesis, have been reported to be involved in plaque stability. Licofelone, a dual COX and 5-LOX inhibitor, has been reported to possess anti-atherogenic effect in rabbit atherosclerosis model. We therefore investigated the anti-atherogenic effect of BHB-TZD [5-(3,5-di-tert-butyl-4-hydroxybenzylidene)thiazolidin-2,4-dione], a dual COX and 5-LOX inhibitor, in low density lipoprotein receptor null (LDLR-/-) mice. Fifteen LDLR-/- mice were fed a western diet (control group), whereas 15 were fed a western diet plus 0.1% (w/w) BHB-TZD (BHB-TZD group). After 8 weeks, the BHB-TZD group had markedly lower serum levels of leukotriene B(4) and prostaglandin E(2) than the control group. Interestingly, BHB-TZD treatment also reduced plasma triglyceride level without significant changes in total cholesterol and HDL levels. Compared with control mice, BHB-TZD fed mice had 52% fewer fatty streak lesions in the aortic sinus, as well as fewer initial lesions in the aortic arch. Macrophage infiltration into the lesions was 40% lower, and collagen and smooth muscle cells were increased by 102% and 96%, respectively, in the BHB-TZD group compared with the control group. In addition, aortic expression of proatherogenic molecules including TNF-alpha, IL-1beta, IL-6, MCP-1 and VCAM-1, was lower in the BHB-TZD group than the control group. BHB-TZD treatment also reduced MMP-2 and MMP-9 expressions in aorta. In conclusion, BHB-TZD effectively attenuated atherosclerosis in mouse model, suggesting its therapeutic potential for atherosclerosis.

Topics: Animals; Aorta, Thoracic; Aortic Diseases; Arachidonate 5-Lipoxygenase; Atherosclerosis; Cholesterol; Cyclooxygenase Inhibitors; Dinoprostone; Disease Models, Animal; Gene Expression Regulation; Hyperlipidemias; Inflammation Mediators; Leukotriene B4; Lipoproteins, HDL; Lipoxygenase Inhibitors; Macrophages; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Myocytes, Smooth Muscle; Prostaglandin-Endoperoxide Synthases; Receptors, LDL; RNA, Messenger; Thiazolidinediones; Time Factors; Triglycerides

Glomerular infiltration of macrophages is a characteristic alteration of renal histopathology in hyperlipidemic renal injury. Each macrophage has two key enzymes to synthesize LTB4:5-lipoxygenase and LTA4 hydrolase. In this study we examined the long-term effects of LTB4 antagonist on real function and histopathology of spontaneously hypercholesterolemic (SHC) rat, which is model of hyperlipidemic renal injury, to see if the LTB4 antagonist could reduce the progression of renal damage. Spontaneously hypercholesterolemic rats fed a normal diet (C) developed end-stage renal failure in 26 weeks, while those fed a diet supplemented with LTB4 antagonist (E) showed normal renal function, and mild histopathological alterations (SCr: C, 1.4 +/- 0.3; E, 0.6 +/- 0.1 mg/dl, P < 0.03) without statistical differences in serum total cholesterol, body weight and blood pressure between two groups. These results suggest that LTB4 plays an important role in progression of hyperlipidemic renal injury.

Topics: Animals; Blood Pressure; Body Weight; Cholesterol; Creatinine; Hyperlipidemias; Immunosuppressive Agents; Kidney; Kidney Diseases; Leukotriene B4; Male; Phenylpropionates; Proteinuria; Rats; Rats, Inbred Strains