1-palmitoyl-2-(5-oxovaleroyl)-sn-glycero-3-phosphorylcholine and Disease-Models--Animal

Oxidized phospholipids (OxPLs) promote inflammation as well as low density lipoprotein (LDL) uptake in a variety of physiological and pathological states. Given the anti-inflammatory role of the cytokine IL-10, we investigated its modulatory effect on the production of oxidized phosphatidylcholines (OxPCs) as well as lipid metabolic responses in global myocardial ischemia/reperfusion (I/R) injury. Increased OxPCs levels, by 1-Palmitoyl-2-(5-oxovaleryl)-sn-glycero-3-phosphocholine (POVPC), promoted oxidative stress (OS) and cell death. OxPCs-mediated-OS, resulted in oxidized low-density lipoprotein receptor 1 (LOX-1) activation and upregulated the expression of toll-like receptor 2 (TLR2). IL-10-induced increase in proprotein convertase subtilisin/kexin type 9 (PCSK9) negatively regulated LOX-1 as well as TLR2 inflammatory responses. Under stress conditions, phosphorylation of sterol regulatory element binding protein 1c (SREBP 1c) was prevented by IL-10. The latter also prevented the generation of OxPCs and reduced their ratio (OxPCs/PCs) during injury. LOX-1 activation also promoted SREBP1c-mediated TGF-βRII expression which was inhibited by IL-10. Both fragmented and non-fragmented OxPCs were elevated during I/R and this effect was attenuated by IL-10. The largest impact (two-threefold change at log

Topics: Animals; Cell Survival; Disease Models, Animal; Interleukin-10; Lipid Metabolism; Male; Myocardial Reperfusion Injury; Myocytes, Cardiac; Oxidation-Reduction; Oxidative Stress; Phosphatidylcholines; Phospholipid Ethers; Rats; Scavenger Receptors, Class E; Toll-Like Receptor 2

The NOD-like receptor family, pyrin domain containing 3 (NLRP3) inflammasome is a multiprotein complex consisting of a receptor, an adaptor protein, and procaspase-1 that induces the secretion of the mature form of IL-1β in response to microbial infection and danger signals. Activation of the NLRP3 inflammasome induced by endogenous danger signal molecules is closely linked to the development and progress of chronic inflammatory diseases. The oxidation of phospholipids occurs upon cellular stress and damage, resulting in the accumulation of oxidized phosphatidylcholines (oxPAPC) such as 1-palmitoyl-2-(5-oxovaleroyl)-sn-glycero-phosphocholine (POVPC) at inflammatory sites. In this study, we investigated whether oxidized phosphatidylcholine induces the activation of NLRP3 inflammasome in macrophages, leading to the secretion of IL-1β. POVPC induced the degradation of procaspase-1 to caspase-1(p10), the cleavage of pro-IL-1β to IL-1β, and oligomerization of ASC in primary mouse bone marrow-derived macrophages. POVPC-induced production of caspase-1, and IL-1β was abolished in macrophages derived from NLRP3- or caspase-1-deficient mice. In an air pouch model and a peritonitis model in mice, POVPC injection resulted in the production of caspase-1(p10), IL-1β, and IL-18 in wild-type, but not in NLRP3-deficient, mice. POVPC-induced inflammasome activation was mediated by mitochondrial reactive oxygen species resulting from intracellular Ca

Topics: Animals; Apoptosis Regulatory Proteins; Calcium; CARD Signaling Adaptor Proteins; Caspase 1; Cells, Cultured; Cyclosporine; Disease Models, Animal; Inflammasomes; Interleukin-1beta; Intracellular Space; Macrophages; Mice, Inbred C57BL; Mice, Knockout; Mitochondria; NLR Family, Pyrin Domain-Containing 3 Protein; Peritonitis; Phagocytosis; Phospholipid Ethers; Potassium; Protein Multimerization; Proteolysis; Reactive Oxygen Species

CD36 has been shown to associate with non-receptor Src kinases to activate mitogen-activated protein kinases and trigger cytoskeletal remodelling, important events in foam cell formation and macrophage migration. Yet, its role in regulating circulating mononuclear phagocyte trafficking to atherosclerotic lesions has not been investigated. The aim of the present study was to investigate the role of CD36 in modulating the recruitment of mononuclear phagocytes to the arterial wall and the associated vascular inflammation, using both pharmacological and genetic approaches.. Apolipoprotein E-deficient (apoE(-/-)) mice fed a high-fat, high-cholesterol diet were treated daily with a CD36 ligand, EP 80317 (300 microg/kg), or 0.9% NaCl for 6 or 12 weeks. Forty-eight hours before sacrifice, mice were injected iv with (111)Indium-labelled macrophages. A 65% (P < 0.001) reduction of labelled macrophage accumulation at aortic lesions was observed in EP 80317-treated mice, mainly at the level of the aortic arch and iliac arteries, correlating with a 43% reduction of atherosclerotic lesion areas. This was associated with reduced phosphorylation of the focal adhesion kinase Pyk2 following stimulation with oxidized phospholipid in a Src kinase- and CD36-dependent manner. At the vascular level, EP 80317 treatment reduced the expression of pro-inflammatory proteins, including NADPH oxidase, inducible nitric oxide synthase, vascular endothelial cell adhesion molecule-1, and CCL2 chemokine. Plasma IL-6 levels were also reduced by 40% (P < 0.05). In contrast, none of these proteins was modulated in EP 80317-treated apoE/CD36 double knockout (apoE(-/-)/CD36(-/-)) mice.. Our results support a role for CD36 signalling in the regulation of mononuclear phagocyte trafficking to atherosclerotic-prone sites and in the associated vascular wall inflammation.

Topics: Animals; Aorta; Apolipoproteins E; Atherosclerosis; CD36 Antigens; Cell Line; Cell Movement; Cells, Cultured; Disease Models, Animal; Focal Adhesion Kinase 2; Lipoproteins, LDL; Macrophages; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Oligopeptides; Phagocytes; Phospholipid Ethers; Receptors, Scavenger; Signal Transduction; src-Family Kinases; Vasculitis

This study was undertaken to investigate the role of the antiangiogenic receptor CD36 during inflammatory corneal neovascularization (CNV).. In a murine model of inflammatory CNV, CD36 expression was evaluated by RT-PCR and immunofluorescence. Mice subjected to CNV were treated topically (thrice daily) with CD36 functionally neutralizing antibodies against the oxidized low-density lipoprotein (oxLDL) and thrombospondin (TSP)-1 sites (clones JC63.1 and FA6-152, respectively). Neovascularization was analyzed by CD31-immunostained corneal flatmounts. The role of the less characterized oxLDL site during angiogenesis was elucidated by using the CD36 ligand 1-palmitoyl 2-(5'-oxovaleroyl) phosphatidylcholine (POVPC; 50, 100 microg/mL) 24 hours after corneal injury for 7 days, whereas in angioregressive studies, POVPC treatments were initiated 10 days after induction of CNV. In this process, VEGF expression was also studied. Effects of CD36 activation were further examined ex vivo using the mouse aortic ring assay.. CD36 expression was upregulated after corneal injury; CD36 was expressed in corneal epithelium, limbus, invading microvessels, and stromal macrophages. Blocking CD36 activity with FA6-152 significantly increased CNV (P <0.001). Conversely, activating CD36 with POVPC dose dependently inhibited CNV (P = 0.003); this effect was blocked by JC61.3. POVPC also significantly regressed preformed blood vessels (P < 0.001). Ex vivo experiments on aortic rings confirmed the angioinhibitory and -regressive effects of POVPC. Because corneal macrophages express CD36 and may partake in angiogenesis via VEGF-A secretion, we surmised that VEGF-A could be modulated by CD36. Indeed, POVPC downregulated VEGF-A expression in a time-dependent fashion (P < 0.001), whereas FA6-152 induced its expression (P < 0.05).. CD36 is involved both physiologically and pharmacologically in inhibition and regression of CNV, by direct effect on endothelial cells and partly by negatively regulating VEGF expression in macrophages.

Topics: Animals; CD36 Antigens; Corneal Injuries; Corneal Neovascularization; Disease Models, Animal; Fluorescent Antibody Technique, Indirect; Lipoproteins, LDL; Macrophages; Male; Mice; Mice, Inbred C57BL; Phospholipid Ethers; Reverse Transcriptase Polymerase Chain Reaction; Thrombospondin 1; Up-Regulation; Vascular Endothelial Growth Factor A

Atherosclerosis can be viewed in part as an inflammatory disease process and may therefore be susceptible to manipulation of the immune state. Interleukin 10 (IL-10) is an inhibitory cytokine produced by activated lymphocytes and monocytes. These studies present evidence that IL-10 can inhibit minimally oxidized LDL (MM-LDL)-induced monocyte-endothelium interaction as well as inhibit atherosclerotic lesion formation in mice fed an atherosclerotic diet. Pretreatment of human aortic endothelial cells (HAECs) for 18, but not 4, hours with recombinant IL-10 caused a significant decrease in MM-LDL-induced monocyte binding. IL-10 was found to be maximally effective at 10 ng/mL. Transfection of HAECs with adenovirus expressing viral bcrf-1 IL-10 (Ad-vIL-10) in a sense but not antisense orientation completely inhibited the ability of MM-LDL to induce monocyte binding. Similar results were obtained with IL-10 or Ad-vIL-10 in HAECs stimulated with oxidized 1-palmitoyl-2-arachidonoyl-sn-glycero-3-phosphorylcholine (OxPAPC). We have previously shown increases in cAMP associated with MM-LDL activation of endothelial cells. The MM-LDL-induced increase in cAMP levels was not inhibited by preincubation with IL-10. In vivo studies demonstrated that mice with a murine IL-10 transgene under the control of the human IL-2 promoter have decreased lesions versus controls on an atherogenic diet (5433+/-4008 mm(2) versus 13 574+/-4212 mm(2); P<0.05), whereas IL-10 null mice have increased lesions (33 250+/-9117 mm(2); P<0.0001) compared with either controls or IL-10 transgenic mice. These studies suggest an important role for IL-10 in the atherosclerotic disease process.

Topics: Adenoviridae; Animals; Aorta; Arteriosclerosis; Cell Adhesion; Cells, Cultured; Disease Models, Animal; Endothelium, Vascular; Gene Expression Regulation, Viral; Humans; In Vitro Techniques; Interleukin-10; Lipoproteins; Mice; Mice, Inbred C57BL; Mice, Knockout; Monocytes; Oxidation-Reduction; Phospholipid Ethers