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1、动脉粥样硬化发生机理的研究进展,赵 明 教授,南方医科大学 基础医学院 病理生理学教研室,二零零九年十二月七日,“Chronic inflammatory disorder of intima of large blood vessels characterised by formation of fibrofatty plaques called atheroma”. Hardening of arteries - Arteriosclerosis,Arteriosclerosis,Lumen,Fibrous cap,Endothelial cells,Atherosclerosis,Lip
2、id metabolism imbalance Inflammation Immuno-response,Lipid metabolism imbalance,Classification of lipids and lipoproteins,Characteristics of lipoproteins,Digestion and metabolism of dietary fat,HDL metabolism and reverse cholesterol transport,Cholesterol efflux and reverse cholesterol transport is m
3、odulated by two receptors,PPAR activators induce cholesterol efflux and reverse cholesterol transport,HDL metabolism: 5 key genes,PPAR: apo A-l, apo A-ll, LPL, ABCA-1 and SR-BI expression,PPARa activators induce cholesterol efflux from human macrophages,CLA-1/SR-BI protein may promote cholesterol re
4、moval from peripheral cells,CLA-1 expression is regulated by PPAR activators in differentiated human macrophages,PPAR activators induce cholesterol efflux and reverse cholesterol transport,LDL,The early lesion: modified lipoproteins and foam cell formation,Classes of Scavenger Receptors,Pluddemann e
5、t al. Methods 43 (2007) 207-217,The Scavenger Receptor Families for modified LDL,The macrophage as an inflammatory mediator,Statins induce PPAR activity,Lumen,Fibrous cap,Endothelial cells,Inflammation,Immuno-response,TLRs and atherosclerosis,CD14,TLR4,MD2,MyD88,TRAM,TRIF,Mal/Tirap,TLR1,TLR2,TLR6,TL
6、R2,TLR4,MyD88,MyD88,Bjrkbacka et al. Nat. Med. (2004) 10: 416-421,Why does oxidized LDL become immunogenic?,Fragmentation of apo B-100 Oxidation of phospholipids Formation of covalent aldehyde (MDA) and amino acid adducts,How Does Immunization With Oxidized LDL Affect Atherosclerosis?,Reduced develo
7、pment of atherosclerosis in rabbits (Palinski et al PNAS 1995, Ameli et al ATVB 1996) Reduced development of atherosclerosis in apo E deficient mice (George et al Atherosclerosis 1998, Freigang et al ATVB 1998, Zhou et al ATVB 2001),Is it possible to produce a vaccine against atherosclerosis?,What s
8、tructures in oxidized LDL are recognized by the immune system? Are these immune responses associated with cardiovascular disease in humans? Can protective immune responses be selectively activated by a vaccine? Can antibodies be used directly to treat atherosclerosis?,Characterization of epitopes in
9、 oxidized LDL by a library of peptide ELISAs,302 peptides, corresponding to the complete amino acid sequence of Apo B-100 Each peptide consists of 20 amino acids with 5 amino acids overlap Modification by malondialdehyde (MDA),Active immunization of apo E null mice with apo B-100 peptide sequences,I
10、mmunization with 100 mg peptides at 6, 9 and 11 weeks of age using Alum as adjuvant High cholesterol diet at 10 weeks of age Atherosclerosis assessed by Oil Red O staining of the descending aorta at 25 weeks of age,Effect of oxidized LDL peptide vaccines on atherosclerosis in mice,% atherosclerosis,
11、P0.01,P0.005,0,0,05,0,1,0,15,0,2,0,25,0,3,Control,Peptide 45,Peptide 210,Peptide 240,Fredrikson GN et al,Effect of immunization with MDA-apoB- 100 peptide 45 on specific IgM, IgG, IgG1 (Th2) and IgG2a (Th1) in apo E null mice,*p0.05, *p0.005,Fredrikson GN et al, Autoimmunity 2005.,Immunization using
12、 MDA-apo B-100 peptides in mice,Reduction of atherosclerosis by up to 70% Remaining plaques contain more collagen and less macrophages Increase in IgG but not in IgM Switch from Th1 to Th2-specific IgG No significant effects on plasma lipids,Passive immunization strategy,Human IgG1 against peptides
13、45 and 210 were produced through screening of a single chain antibody fragment library and subsequent cloning into a pcDNA3 vector Apo E knockout mice were given high cholesterol diet from 6 weeks of age Treated with 0.5 mg antibody at 21, 22 and 23 weeks of age and sacrificed two weeks later Effect
14、s assessed by ORO staining of descending aorta, Trichrome Masson staining and macrophage immunostaining of subvalvular plaques,Effect of passive immunization with recombinant human IgG against peptide 45 on early atherosclerosis in mice,Schiopu et al, Circulation 2004,Regression of aortic plaque are
15、a in antibody treated Apobec-1-/-/LDLr -/- mice,Schiopu A et al., JACC 2007,Recombinant human antibodies to MDA-apoB-100 peptides upregulate ABCA-1 expression in vivo and in vitro,Schiopu A et al., JACC 2007,Recombinant human antibodies to MDA-apoB-100 peptides block oxidized LDL-induced monocyte MC
16、P-1 production in vitro,Schiopu A et al., JACC 2007,Conclusions,The identification of the immunogenic structures in oxidized LDL has made it possible to develop novel therapeutic approaches for treatment of atherosclerosis. Studies performed in atherosclerosis-prone mice demonstrate that both peptide-based vaccines and recombinant IgG targeting epitopes in oxidized LDL significantly reduce atherosclerosis.,Atherosclerosis,Lipid metabolism imbalance Inflammation Immuno-response,Thank you !,