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