Towards Immune Modulation against Vulnerable Plaque
Göran K HanssonCenter for Molecular Medicine
Karolinska InstitutetStockholm, Sweden
Vulnerable Plaque SymposiumChicago, IL, November 2002
Hansson, Libby, Schönbeck & Yan, Circ Res 2002
Potential targets for immunomodulation of
atherosclerosis• Specific antigens
– oxLDL, HSP65, 2GpI, microbial
• C pneum, CMV, others
• Co-stimulatory molecules– CD40/CD40L, CD28/B7
• Cytokines– IFN, TNF (aggravating)– IL-10, TGF (protective)
• Vaccines• Recombinant proteins• Antibodies• Cells• Small molecule drugs
Atherosclerosis in the absence of adaptive immunity?
(G K Hansson & J Nilsson, in: Crawford & DiMarco, Cardiology)
CD4+ T cells aggravate atherosclerosis in immunodeficient apoExSCID mice
*
ApoE-SCID
ApoE-
T and B cells No CD4+T Yes transfer
Aortic lesion size
Zhou, Nicoletti,Elhage & HanssonCirc 102:29192000
ApoE-SCID
Immunosuppression to reduce CD4+ T cell activity?
• General immunosuppression is likely to reduce atherosclerosis– Some support from animal studies
• But substantial side effects– Infections– Direct vascular effects of drugs
• Therefore, general immunosuppression is unlikely to be used to treat atherosclerosis or even vulnerable plaque
Complexity of immune regulatory networks
• Counterbalancing cell subsets• Idiotypic antibody networks• Regulatory cytokines
The Th1/Th2 Paradigm
Th
IL-12
MHCPeptide
TCRTCR
IFN-IL-18
Th1
IFN-
M
IFN-B
Ab
DTHInflammationAPC
APC Th
IL-4Th2Th2
B
IL-3, 5
IL-4IL-10IL-13
-
IL-4, 10, 13
Antibodies
Allergy
Hypothesis: Th1/Th2 balance controls atherosclerosis
– Th1 cells dominate in lesions and are proatherogenic
• CD4+ Th1 cells (Hansson 89; Uyemura 96; Frostegård 99)
• Interferon-, TNF-; IL-12, IL-18 (Zhou 00; Mallat 01; Daugherty 01)
– Th2 cytokines that inhibit Th1 may be antiatherogenic?
– IL-10-/- B6 mice develop larger fatty streaks– IL-10 administration reduces disease
» Mallat et al; Pinderski et al. 99
Increased atherosclerosis in IL-10 deficient apoE-/- mice
IL10-/- E-/- IL10+/+ E-/-
Caligiuri, Hansson, Rudling, Michel, Nicoletti 2002
*100
50
Lesion size(x 103 µm2)in 16 wks old mice
Antiatherosclerotic cytokines- useful for therapy?
• Powerful, direct approach• Recombinant cytokines available • But these cytokines are usually
immunosuppressive / antiinflammatory, therefore– Increased sensitivity to infections– Cytokine-specific side effects
• E.g. TGF – fibrosis
• Therefore, these cytokines might be useful in acute coronary syndromes,
• although not in chronic atherosclerosis
InflammationRepair
Innate immunity / TLRsAdaptive Th1 immunity
IFN- TNF-IL-1
Inhibitory cytokinesCells?
IL-10TGF-
Ab?
Accelerated atheroPlaque activation
Reduced atheroStable plaqueSilent disease
Immune regulation of plaque activity
B cells of atherosclerotic mice carry atheroprotective immunity
0
50
100
150
200
250
Sham Sx Sx SxTransfer - - T B
*
*
‡
‡Lesi
on s
ize
Caligiuri et al, JCI 109:745, 2002
ApoE miceSx, trf 6 wk ageAnalysis 18 wk
Atheroprotective immunity
• Carried by spleen B cells• Reduces lesion size and stage• Reduces CD4+ T cell infiltration in
lesions• Correlates with anti-oxLDL antibodies• Protective effect of antibodies?
– Clearance of oxLDL?
Protective immunity against atherosclerosis
• Can we induce it by immunization?
• A vaccination strategy against atherosclerosis?
Protective immunization1. Oxidized LDL
Parenteral immunization (sc)Model: Mutant rabbits, miceAntigen: OxLDL, MDA-LDL
Freund´s adjuvantRepeated inj 3 wk intervals
Significant protection after 3 months!Palinski PNAS 95; Ameli ATVB 96;George Athero 99; Zhou ATVB 00
MDA-LDL ”vaccination” reduces atherosclerosis
Immunogen (PBS) Plaque MDA-LDLextract
ApoE-/- miceImmun wk 6 / FCABoost wk 8,10,12,14Analysis wk 18
Zhou et al, ATVB 2000
Protective immunization2. Heat shock protein 65/60
• HSP60 released upon cell injury and in atherosclerosis– Wick, Xu et al. 1992
• HSP65/60 X-reacts man-microbe• Mucosal administration of HSP65
– Nasal, oral• Reduced lesions in LDLR mice
– Maron, Libby, Weiner, Circ 2002– Harats, Shoenfeld, George, JACC 2002
InflammationRepair
Innate immunity / TLRsAdaptive Th1 immunity
IFN- TNF-IL-1
Inhibitory cytokinesProtective B cells
IL-10TGF-
Ab?
M activationEndothelial activation
RadicalsProteinases
Prothrombotic state
AntiinflammationFibrosis
SMC proliferationAntibody clearance
Immune regulation of plaque activity
Vaccine
Small molecule drugs that modulate athero-immunity
• Pentoxifyllin– Inhibits Th1 immune responses– Inhibits atherosclerosis in mice
• Laurat et al Circ 2001
• Statins– Inhibit Th1 responses!
• Kwak Nat Med 2000; Youssef Nature 2002– Inhibit atherosclerosis in mice and men
Statins inhibit Th1 immunity• Downregulate interferon- induced
HLA-II transcription in macrophages– Kwak, Mach et al, Nature Med 2000
• Inhibit Th1 signalling• Increase Th2 cytokines• Inhibit autoimmune encephalomyelitis
– Youssef, Steinman et al, Nature 2002
InflammationRepair
Innate immunity / TLRsAdaptive Th1 immunity
IFN- TNF-IL-1
Inhibitory cytokinesProtective B cells
IL-10TGF-
Ab
M activationEndothelial activation
RadicalsProteinases
Prothrombotic state
AntiinflammationFibrosis
SMC proliferationAntibody clearance
Immune modulation of vulnerable plaque
VaccinesDrugs