Prsentation PowerPoint

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Biological effects of PPARa agonists And
Microvascular Disease Prevention
Bart Staels
Département d'Athérosclérose, INSERM UR545,
Institut Pasteur de Lille, and Université de
Lille 2, France
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FIELD Effective on Microvascular and Peripheral
Vascular Disease
Retinopathy
Albuminuria
0
5
10
15
20
25
30
35
Risk Reduction ()
Effects independent of the degree of glycemic
control (HbA1c), concomitant medications or
reduction in blood pressure!
Lancet. 200536618491861
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Mechanisms of Hyperglycemia-induced vascular
dysfunction
Nathan DM et al NEJM 20033482294 Khaw KT et al
BMJ 200132215 Shanmugam et al Diabetes
2003521256 Shrivastava AV et al Int J Mol Med
2002985 Yan SF et al Circ Res 2003931159
Zimmermann R et al Diabetes 2001501643
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Examples of Drugs in Development for
Microvascular Disease
Ruboxistaurin (Arxxant, Lilly) PKC-beta
inhibitor blocking excess glucose effects
gtretinopathy and possibly nephro- and
neuropathy Benfotiamine (micronutrient)
blocks the hexosamine pathway gtmicrovascular
complications Copper-zinc superoxide
dismutase catalytic anti-oxidant
gtmicrovascular complications Hyaluronidase
(Vitrase, ISTA) slows progression of diabetic
retinopathy and liquefies blood clots in
vitreous humor gtretinopathy Pegaptanib
(Macugen, Pfizer) inhibits VEGF in vitreous
humor gttreatment of diabetic macular edema
and diabetic retinopathy
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PPARa and Microvascular Disease
PPARa molecular actions
PPARa metabolic actions
PPARa vascular actions
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Control of gene expression by PPARa
PPARa agonists (fatty acids, fenofibrate,
gemfibrozil )
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Molecular mechanisms of PPARs on
inflammation example of the NFkB signalling
pathway
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Aortas from PPAR?-null mice display an
exacerbated inflammatory response to LPS
stimulation
/
-/-
150
IL-6 (U/ ug DNA)
100
50
-

LPS
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PPARa agonist treatment decreases Western
diet-induced IL-6 expression in aortas of apo E2
KI mice
400
300
IL-6 mRNA
200
100
-
Western diet

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PPARa and Microvascular Disease
PPARa molecular actions
PPARa metabolic actions
PPARa vascular actions
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PPARa modulates triglyceride metabolism
PPARa agonists
Liver
PPARa
m
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Plasma TG
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Atherogenicity of Small Dense LDL
VLDL rich in apo C-III
VLDL poor in apo C-III
Cholesteryl ester
TG
CETP
Cholesteryl ester
CETP
LDL
Large buoyant LDL
TG
Small dense LDL
LDL receptor
Macrophage
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Anti-diabetic and Cardioprotective activities of
Adiponectin
1. Yamauchi et al. Nature Medicine 2001 7
941-946 2. Berg et al. Nature Medicine 2001 7
947-953 3. Ouchi et al. Circulation 2001 103
1057-1063 4. Yokota et al. Blood 2000 96
1723-1732 5. Ouchi et al. Circulation 1999 100
2473-2476
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FFAs, insulin resistance and inflammation the
link between type 2 diabetes and cardiovascular
disease ?
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PPARa and Microvascular Disease
PPARa molecular actions
PPARa metabolic actions
PPARa vascular actions
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PPARa improves vascular function by acting on
different vascular cell types
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PPARa and Microvascular Disease
PPARa molecular actions
PPARa metabolic actions
PPARa vascular actions
endothelial cells
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Fenofibrate improves post-ischaemic flow mediated
dilation of the brachial artery in type 2
diabetic patients
2.5
2
1.5
1
Change in FMD ()
0.5
0
-0.5
-1
Placebo
Fenofibrate
Watts et al Diabetologia 2002 Playford et al Am
J Cardiol 2002
P 0.024
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Causes and consequences of endothelialdysfunction
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Endothelial dysfunction in type 2 diabetes is
characterized by unbalanced activity of
vasoactive factors
Endothelium
VASOCONSTRICTORS
VASODILATORS
NO (eNOS)
endothelin-1
prostacyclin (COX)
Vascular tone
Cardillo et al. Circulation 2002,1061783 Cardill
o et al. Circulation 1999,100820 Mather et al.
Diabetes 2002,513517
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Key effects of Nitric Oxide on Vascular Function
NO (Nitric Oxide)
Endothelium
Coron. Artery Dis. 199910277-286
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Fibrates increase eNOS expression and activityin
endothelial cells
Wang Y. et al. Atherosclerosis 2005
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R
R
Me
2
Me
2
ADMA
Me
ADMA
2
Me
2
ADMA
ADMA
DDAH2
DDAH1
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Mechanism inhibition of NFkB-reduced DDAH
activity
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Pathophysiology of Oxidative stress
Excessive oxidative stress
Kunsch C Medford RM Circ Res 1999,85,753-766
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Mechanisms of ROS Generation
Inflammatory stimuli
Zn-SOD Catalase GSH-Px/Rd
Mitochondria
Mn-SOD ATP
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PPARa agonists modulate oxidative stress in
endothelial cells
DCF-DA
DCF DA
H2O2
Fluorescent product
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Pro-atherogenic activity of the angiotensin-II
pathway
Angiotensin II
AT1R
ROS
NFkB
AP1
Endothelin 1
Vasoconstriction
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Vascular Actions of Insulin
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Selective Vascular Insulin Resistance
Insulin
InsRec
PI3K
Akt
ecNOS
MMP29
Glucose metabolism
TIMP
Apoptosis
Muscle
Endothelial Smooth Muscle Cell
Cusi et al. JCI 2000,105311 Montagnani et al.
J.Biol.Chem. 2002,2771794
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PPARa improves endothelial function
PPARa
Leucocyte recrutement
Vasorelaxation
Vasoconstriction
eNOS
ET-1
VCAM
Celermayer et al. Lancet 1992
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PPARa and Microvascular Disease
PPARa molecular actions
PPARa metabolic actions
PPARa vascular actions
endothelial cells
macrophages
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PPARa and reverse cholesterol transport
LDL
PPAR
FC
EC
FC
FC
EC
FC SM
Macrophage
Chinetti G et al. Curr. Opin. Lipidol. 2003,
14459
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PPARa agonists reduce tissue factor expression
100
_
GW2331
WY14643
ATRA
80
-
28 S
TF mRNA (Percent of IL-1b- stimulated control)
60
-
TF
18 S
40
-
18 S
36B4

20
0
_
ATRA
WY14643
GW2331
and MMP-9 expression in human macrophages
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PPARa and Microvascular Disease
PPARa molecular actions
PPARa metabolic actions
PPARa vascular actions
endothelial cells
macrophages
smooth muscle cells
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PPARa inhibits SMC proliferation
Human SMCs
40
35
Vehicle
GW7647 (100 nM)
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GW7647 (300 nM)
25
GW7647 (600 nM)
DNA content (X105)
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15
10


5

24
48
72
96
0
Time (h)
Gizard et al. JCI 2005115(11) 3228-3238
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PPARa activation inhibits neointima formation
after carotid injury in vivo in mice
Massons trichrome staining
PPARa -/-
PPARa /
PPARa / fenofibrate
internal elastic lamina
Gizard et al. JCI 2005115(11) 3228-3238
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PPARa inhibits TGFb-induced b5-Integrin
expression and SMC migration
TGFb1
Sp1/3
Pol II
transcription
Smad4
-1
-53
-48
?5-Integrin
Migration
Kintscher et al. Circ Res 200291e35
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PPARa activation inhibits basal and
TGFb-stimulated GAG production by SMCs decrease
of PG chain length
Nigro et al. Atherosclerosis 2002162119-129
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A modulatory role for PPARa in diabetic
nephropathy?

• PPARa is expressed in proximal tubules and
  glomerular mesangial cells
• PPARa is implicated in renal metabolic control
• PPARa influences TGFb expression and signaling
• PPARa-deficient mice display enhanced cortical
  necrosis and worse kidney function upon I/R
  injury
• PPARa agonists improve diabetic nephropathy in
  obese db/db mice
• PPARa deficient mice display renal inflammation,
  glomerular cell apoptosis and mesangial matrix
  expansion streptozotocin-induced type 1 diabetic
  nephropathy

Guan Y. J.Am.Soc.Nephrol.2004,152801 Portilla
et al. Am.J.Renal.Physiol. 2000,278F667 Park et
al. J.Am.Soc.Nephrol. 2003,14393A Wilmer et al.
Antioxid.Redox.Signal. 2002,4877 Park et al,
Diabetes, 2006, 55 885
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Albuminuria and Alterations in Proximal Tubules
upon starvation in PPARa-deficient mice
Fed
Starved
vesicular structures
Kamijo et al. J Am Soc Nephrol 2002,131691
Lightmicroscopie analysis
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PPARa deficiency results in kidney fibrosis
associated with increased glomerular collagen
content, TGFbeta and osteopontin expression and
enhanced macrophage infiltration.Fenofibrate
treatment exerts opposite effects.
Park et al. Diabetes 2006,55885
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PPARa and diabetic retinopathy

• Inhibition of apoptosis in human umbilical vein
  endothelial cells by human PPARa (related to
  intracellular esterified-cholesterol and ABCA1)
  (Inoue et al, J Atheroscler and Thromb, 2003, 10
  99-108)
• PPARa ligands inhibit VEGFR2 expression and block
  VEGFR signaling Anti-angiogenic action through
  targeting of VEGFR may be a new approach to
  blocking hypoxia-driven angiogenesis (Sato,
  Nippon Rinsho, 2005, 63(4) 603-608)
• Prevention of hard retinal exudation development
  in patients (63) with diabetic retinopathy
  (Harrold et al, Diabetes, 1969, 18(5) 285-291)
  Clofibrate is the treatment of choice in
  exudative diabetic retinopathy  (Dorne et al,
  Arch Ophtalmo, 197737(5)393-400)

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PPARa improves vascular function by acting on
different vascular cell types
PPARa
SMC Vascular remodelling
Endothelial cells Angiotensin II Endothelin-1 sig
nalling
Macrophages Inflammation control
Cholesterol homeostasis
Microvascular protection
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Coworkers
Dépt.dAthérosclérose G.Chinetti V.Clavey C.Fieve
t P.Gervois F.Gizard C.Glineur N.Hennuyer S.Lestav
el A.Tailleux G.Torpier J.-C.Fruchart
Univ.J.Verne, Amiens C.Amant H.Sevestre J.Rochette
Dept.Pharm.Sci., Milano S.Bellosta A.Corsini
NCI, Amsterdam P.Krimpenfort
Institut Pasteur, Lille H.Mezdour
UCLA U.Kintscher R.Law
TNO, Leiden R.Kleemann T.Kooistra