Oxidized LDL and Atherosclerosis ー酸化LDLと粥状動脈硬化ー
京都大学大学院医学研究科循環器内科
北 徹
心血管病
癌
Cardiovascular Diseases30%
Familial Hypercholesterolemia 家族性高コレステロール血症
Elevated concentration of Low density lipoprotein (LDL)
Inheritance as an autosomal dominant trait： Gene mutation of the LDL receptor
heterozygote:1 in 500 persons
homozygotes:1 in 1 million persons
Major cause of death:myocardial infarction（心筋梗塞）
->This disease is a good model to investigate how plasma level of LDL is elevated and also how elevated LDL causes atherosclerosis.
Hepatic expression of LDL-receptor regurates
the plasma level of LDL.
HMG-coA Reductase Inhibitor(Statin) upregurates hepatic expression of LDL-receptor!
Therefore patient’s high level of LDL could be reduced.
What is the Missing Link between high level of LDL and Atherosclerosis ?
Scheme of Atheromatous Plaque
Macrophages
T-lymphocytes
Atheromatous
plaque
Lumen
Fibrous cap
Endothelial cells
Foam Cell
（泡沫細胞）
Atheroma（粥腫）
Monocyte migration through endothelial cells
1, Rolling mediated
by selectins
2, Sticking mediated by adhesion
molecules such as VCAM-1 and ICAM-1
Endothelial
cells
LDL
3, Transmigration molecules
such as JAM and PECAM
Macrophage
Foam cell
Oxidized LDL
Lyso-PC
Smooth muscle cell
M-CSF-c-fms pathway
MCP-1-CXCR2 pathway
Murayama, T. et al. Circulation 99:1740, 1999
Blockade of M-CSF signal pathway by monoclonal antibody causes marked reduction of early atherosclerosis in ApoE-deficient Mice
Boring, L. et al. Nature 394, 894-897, 1998
Reduced Atherosclerosis in chemokine MCP-1 receptor, CCR2 -/- mice
ApoE KO mice
Foam Cell
（泡沫細胞）
Atheroma（粥腫）
Foam Cell Formation
Monocyte
Macrophage
Foam cell
Blood stream
Tissue (arterial wall)
LDL receptor:
(+)
(-)
(-)
Question: How does macrophage intake
LDL-derived cholesteryl esters ?
Dr.Henriksen’s Study:
LDL is incuvated with endothelial cells in F-10 medium.After incuvation,he takes LDL from medium and incuvated this LDL with Macrophage.
Macrophage becomes to be Foam cells!!
->This expriment is prevented by EDTA!
Probucol
１）Antioxidant Property
２）Probucol exists in LDLparticle
３）Prevention and Regression of Xanthomas
Modified (Oxidized) LDL theory
T. Kita et al. PNAS (1987) 5928
An antioxidant probucol prevents atherosclerosis formation in WHHL (LDL receptor-defective) rabbits
WHHL rabbit
Probucol (-)
Probucol (+)
Missing Link between LDL and Atherosclerosis is Oxidized LDL
Oxidized LDL in atherogenesis
LDL
Oxidized LDL
(Lipid peroxide, oxysterol, oxidized fatty acid, lysophosphatidylcholine)
Smooth muscle cells
CD40 &CD40L
MMPs
apoptosis
Macrophages
Activation
Foam cell formation
Tissue Factor
Endothelial cells
MMPs
HB-EGF
PDGF-A & -B chains
ICAM-1 &VCAM-1
COX-2
NO production
The Scavenger Receptor Families
for modified LDL
Collagen-like
SRCR
SR-A
MARCO
Class A
CD36
SR-B1
immunodominant
Class B
EGF-like
SR-EC
LOX-1
Lectin-like
SR-PSOX
Chemokine-
domain
Mucin-
stalk
LOX-1 (Lectin-like Oxidized Receptor-1)
Endocytic receptor for atherogenic oxidized LDL,
initially identified in vascular endothelial cells.
40-50kDa type II membrane glycoprotein with short cytoplasmic tail
and extracellular C-type lectin-like domain.
Expressed also in smooth muscle cells, macrophages in advanced atherosclerotic plaque.
The expression is dramatically increased by various stimuli.
TNF-a, TGF-b, PMA, oxidized LDL, angiotensin-II
Mechanical stress (fluid shear stress).
Physiological ligands other than oxLDL
bacteria and apoptotic cells etc.
Soluble forms
Early lesions
Advanced plaques
Kataoka H, et al., Circulation: 1999
Early stage : Endothelial cells
(low magnification)
Expression of LOX-1 in Human Carotid Artery Endoarterectomy Samples
Advanced stage : Macrophages and
Intimal Smooth Muscle Cells
(high magnification)
(low magnification)
(high magnification)
Macrophages
Smooth muscle cells
LOX-1 mediates
Ox-LDL-induced apoptosis of vascular smooth muscle cell
Kataoka H, et al.,
Arterioscler, Thromb. Vasc. Biol: 2001
Neutralizing antibody for LOX-1 inhibits Ox-LDL-induced modulation of Bax and Bcl-2 expression in vascular smooth muscle cells
Kataoka H, et al.; ATVB: 2001
Colocalization of LOX-1 and Bax in human atherosclerotic lesion
LOX-1
Bax
Merge
Lectin-like oxidized LDL receptor-1
(LOX-1)
TNF-a
TGF-b
Angiotensin II
Oxidized LDL
Apoptosis of SMC
Unstable plaque
Oxidized LDL-LOX-1 pathway appears to be responsible for smooth muscle cell apoptosis in atherosclerotic lesions ->suggesting for induction of plaque rupture
Rationale for measurement of soluble LOX-1
Inducible expression of LOX-1 by various stimuli.
Proinflammatory stimuli (TNF-a, TGF-b, PMA, )
oxidized LDL,angiotensin-II
hypoxia
Mechanical stress (fluid shear stress).
In human advanced atherosclerotic lesion,
LOX-1 is remarakably expressed
in intimal vascular smooth muscle cells(SMC)
LOX-1 is involved in SMC apoptosis by oxidized LDL
-might involved in plaque rupture followed by ACS-
Soluble LOX-1 (sLOX-1)
Soluble LOX-1
Patients population (521pts)
Consecutive 427 pts undergoing coronary angiography
Intact coronary: 52 pts with intact coronary
controlled CHD: 122 pts with coronary atherosclerosis w/o symptom and ischemia
ischemic CHD: 173pts with symptomatic stable AP necessitating PCI or CABG
ACS: 80pts with acute coronary syndrome
34 patients with non-cardiac acute illness
60 patients with non-cardiac chronic illness
Soluble LOX-1 was elevated in patients with acute coronary syndrome
17%
30%
66%
95%
30%
Acute coronary syndrome (ACS) showed significantly higher serum sLOX-1 levels by new CLEIA for sLOX-1
I: Intact Coronary
II: Controled
CHD
III: Ischemic CHD
(PCI & CABG)
IV: ACS
急性冠症候群では特異的に可溶型LOX-1の血中濃度が上昇するー高感度CRPとの比較
Hayashida K, Kume N et al: 2005 in circulation
sLOX-1 levels are elevated at the early stage of acute coronary syndrome
Receiver-Operating-Characteristics curves for soluble LOX-1 and CRP for diagnosis of ACS
SUMMARY for serum soluble LOX-1
Soluble LOX-1 in serum is a novel marker of acute coronary syndrome, which is specific and independent of hs-CRP and troponin T.
Serum soluble LOX-1 appears a superior marker at the earliest stage of acute coronary syndrome, and may also be useful to predict the onset of acute coronary syndrome.
PMSF and argatroban inhibit production