The Critical Role of Interleukin1 in Rheumatoid Arthritis

1
The Critical Role of Interleukin-1 in Rheumatoid
Arthritis

2
IL-1b and TNF-a Proinflammatory Cytokines in the
Rheumatoid Joint
High endothelial venule
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Synovial membrane
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IL-8
PGE2
IL-6
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Capsule
Synovial space
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Pannus
Osteoblasts
Osteoclasts
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PGE2 prostaglandin-E2
Dinarello C, Moldawer L. Proinflammatory and
Anti-inflammatory Cytokines in Rheumatoid
Arthritis A Primer for Clinicians. 3rd ed.
Thousand Oaks, Ca, USA Amgen Inc. 2001.
3
IL-1 and TNF-? Have a Number of Overlapping
Proinflammatory Effects
Proinflammatory effects of IL-1
Proinflammatory effects of TNF-?
?COX-2?PGE2?NO?Adhesion molecules?Chemokines?
Collagenases?IL-6
?TNF-??Osteoclast activation ?Angiogenic
factors
?IL-1 ?cell death
COX-2 cyclo-oxygenase type 2 PGE2
prostaglandin-E2 NO nitric oxide
4
IL-1? Production Occurs Independently of TNF
IL-1? Levels in the Joint at Onset of
Streptococcal Cell Wall-Induced Arthritis
700
600
500
Synovial IL-1? (pg/mL)
400
300
200
100
0
Control
Anti-TNF
Control
TNF/
van den Berg W. Ann Rheum Dis. 200059(suppl
1)i81-i84.
5
IL-1 Plays a Pivotal Role in the Inflammatory and
Destructive Processes of RA
IL-1
Activates monocytes/macrophages
Activates chondrocytes
Induces fibroblast proliferation
Activates osteoclasts
Inflammation
Synovial pannus formation
Cartilage breakdown
Bone resorption
6
IL-1 is a Pivotal Cytokine Involved in the
Pathogenesis of RA

• Inflammation
• Prostaglandin-E2, nitric oxide, and
  cyclo-oxygenase type 2 production
• Cytokine gene expression(eg, TNF-?, IL-6)
• Chemokine and angiogenic factor expression
• Cell adhesion molecule expression
• T- and B-lymphocyte activation

• Joint cells and matrix
• Matrix metalloprotease (MMP) production by
  chondrocytes and synovial cells
• Cartilage degradation (MMPs)
• Synovial cell proliferation
• Resorption of bone by induction of osteoclast
  activity
• Impairment of cartilage repair by inhibition of
  proteoglycan and type II collagen synthesis

7
Plasma IL-1b Correlates With RA Disease Activity
30 25 20 15 10 5
n 35 r 0.358 P lt0.05
90
n 37 r 0.527 P lt0.001
60
Ritchie Articular Index
Erythrocyte Sedimentation Rate (mm/h)
30
0
3
4
5
6
50
100
150
200
250
Log Plasma IL-1? (pg/mL)
Plasma IL-1b (pg/mL)
Eastgate J, et al. Lancet. 19882706-708.
8
Anti-TNF Antibody Treatment Does Not Decrease
Systemic IL-1? Levels in RA Patients
Infliximab 10 mg/kg (n 22)
7.5
Placebo (n 24)
5.0
Median Immunoreactive IL-1? (pg/mL)
2.5
0
0
10
20
30
Time (Days)
Charles P, et al. J Immunol. 19991631521-1528.
9
The IL-1 Family Consists of Ligands and Receptors

• Ligands
• IL-1? agonist
• IL-1? agonist
• IL-1Ra antagonist
• Receptors
• IL-1 receptor type I functional
• IL-1 receptor type II inactive (decoy
  receptor)
• Soluble receptors
• soluble IL-1 receptor type I binds IL-1Ra
  preferentially
• soluble IL-1 receptor type II binds IL-1?
  preferentially

10
IL-1b Activates Cell Signalling Through IL-1
Receptors
sIL-1RII
IL-1?
sIL-1RI
High-affinity binding of IL-1 to IL-1RI
heterodimer complex
IL-1RAcP
IL-1RII (decoy receptor)
IL-1 RI
No signal
Toll domains
IRAK
Signal
IRAK
sIL-1RI soluble IL-1 receptor type I sIL-1RII
soluble IL-1 receptor type II IL-1RAcP
IL-1R accessory protein IRAK
IL-1RI-associated kinase
Nucleus
Dinarello C, Moldawer L. Proinflammatory and
Anti-inflammatory Cytokines in Rheumatoid
Arthritis A Primer for Clinicians. 3rd ed.
Thousand Oaks, Ca Amgen Inc. 2001.
11
IL-1 Production and Action may Be Inhibited by
Interfering With Different Mechanisms
ICE inhibitors
sIL-1RII
Direct cellcell contact
IL-1RII
F/S
DC/APCcytokines?
MMPsPGE2
IL-1RI
TH1
IL-1
M?
TNF-?
Apo A-IAnti-CD69Anti-CD11
IL-1Ra
APC antigen presenting cell Apo A-I
apolipoprotein A-I DC dendritic cell F/S
fibroblast/synoviocyte ICE IL-1 converting
enzyme IL-1Ra IL-1 receptor antagonist
IL-1RI IL-1 receptor type I sIL-1RII
soluble IL-1 receptor type II M?
monocytemacrophage MMPs matrix
metalloproteases PGE2 prostaglandin-E2 TH1
T helper cell type 1
Dayer J-M, et al. Curr Opin Rheumatol.
200113170-176.
12
Endogenous IL-1 Receptor AntagonistA Naturally
Occurring Antagonist of IL-1

• A member of the IL-1 family
• Structurally related to IL-1?
• Produced constitutively and during inflammation
• Binds to IL-1 receptor type I (IL-1RI)
• Occupies, but does not activate, IL-1RI
• Does not allow docking of IL-1R accessory protein
• A pure receptor antagonist

13
IL-1 and Endogenous IL-1Ra Are Involved in a
Number of Cellular Processes
PAF platelet activating factor PGE2
prostaglandin-E2 IL-1Ra interleukin-1 receptor
antagonist
Dinarello C. N Engl J Med. 2000343732-734.
14
IL-1Ra Binds to IL-1RI but DoesNot Activate Cell
Signalling
IL-1Ra
IL-1Ra
High-affinity binding of IL-1 to
IL-1RIheterodimer complex
IL-1?
IL-1RAcP
IL-1RI
Toll Domains
IRAK
No signal
Signal
No signal
IL-1Ra IL-1 receptor antagonist IL-1RI IL-1
receptor type I IRAK IL-1RI-associated
kinase IL-1RAcP IL-1R accessory protein
Nucleus
Dinarello C, Moldawer L. Proinflammatory and
Anti-inflammatory Cytokines in Rheumatoid
Arthritis A Primer for Clinicians. 3rd ed.
Thousand Oaks, Ca Amgen Inc. 2001.
15
IL-1 Induces Chronic Arthritis as Supported by
Animal Models

• Repeated intra-articular injections of IL-1 in
  rat knees induces arthritis1
• Continuous infusion of IL-1 into rabbit knees
  induces arthritis2
• IL-1 injection or infusion triggers onset of
  arthritis in mice3,4
• Intra-articular expression of IL-1? in rabbit
  synovium by gene transfer induces arthritis5
• IL-1? transgenic mice develop arthritis early6
• Mice lacking IL-1 receptor antagonist develop
  spontaneous arthritis7

1. Chandrasekhar S, et al. Clin Immunol
Immunopathol. 199055382-400.2. Feige U, et al.
Int J Tissue React. 198911225-238.3. Hom J, et
al. J Immunol. 1988141834-841.4. Hom J, et al.
Clin Immunol Immunopathol. 199055109-119.5.
Ghivizzani S, et al. J Immunol.
19971593604-3612.6. Niki Y, et al. J Clin
Invest. 20011071127-1135.7. Horai R, et al. J
Exp Med. 2000191313-320.
16
Preclinical Assessment of IL-1raAnimal Models
of Arthritis
Inject type II collagen, or adjuvant
Assessments paw swelling, histology, bone
markers, X-ray
IL-1ratreatment (SC, IP, or infusion)
Arthritis develops
Therapeutic treatment period
810 days
714 days
IL-1ra IL-1 receptor antagonist SC
subcutaneous IP intraperitoneal
17
Treatment With IL-1ra Reduces Inflammation in
Collagen-Induced Arthritis
VehicleUntreated normal0.04 mg/kg/h0.2
mg/kg/h1.0 mg/kg/h5.0 mg/kg/h
0.36
n 8 per group
0.34
0.32
Mean Ankle Joint Diameter (inches) SE
0.30
0.28
0.26
0.24
0
1
2
3
4
5
6
7
Day of Arthritis
IL-1ra IL-1 receptor antagonist
Bendele A, et al. Arthritis Rheum.
199942498-506.
18
IL-1Ra-Deficient Animals Spontaneously Develop
Erosive Arthritis
Balb/cA IL-1Ra/ affected
Balb/cA IL-1Ra/ normal
IL-1Ra interleukin-1 receptor antagonist
Horai R, et al. J Exp Med. 2000191313-320.
19
IL-1ra Reduces Inflammation and Destruction
Collagen-Induced Arthritis
Inflammation Score
Cartilage Score
4
4
3
3

Mean Histological Score ( SE)
Mean Histological Score ( SE)

2
2


1
1

0
0
0
0.04
0.2
1
5
0
0.04
0.2
1
5
Bone Damage Score
Pannus Score
4
4
3
3

Mean Histological Score ( SE)
Mean Histological Score ( SE)
2
2


1
1


0
0
0
0.04
0.2
1
5
0
0.04
0.2
1
5
IL-1ra (mg/kg/h)
IL-1ra (mg/kg/h)
P ?0.05 vs vehicle IL-1ra interleukin-1
receptor antagonist
Adapted from Bendele A, et al. Arthritis Rheum.
199942498-506.
20
IL-1 is a Key Mediator of Disease in RA

• IL-1 gt TNF-? induces production of matrix
  metalloproteases and prostaglandin-E2 by
  synovial cells
• IL-1 mediates bone resorption and cartilage
  destruction
• IL-1 impairs repair processes (eg, proteoglycan
  synthesis)
• IL-1 receptor antagonist selectively inhibits
  IL-1-mediated responses

21
Different Mechanisms Drive Cartilage and Bone
Loss in RA

• The cellular, biochemical, and molecular
  mechanisms involved in cartilage and bone
  remodelling differ
• the degradation and synthetic repair of articular
  cartilage are mediated by chondrocytes
• the resorption and formation of bone are mediated
  by osteoclasts and osteoblasts, respectively
• An understanding of these different mechanisms is
  essential for
• gaining insight into the pathogenesis of bone and
  cartilage loss
• development of rational approaches for preventing
  joint destruction

22
Role of IL-1 in Joint Destruction

• IL-1 has a higher potency for inducing joint
  destruction than TNF
• In TNF-transgenic mice, arthritis can be
  completely inhibited by blocking IL-1 signalling
• TNF-independent IL-1 production has been shown in
  models
• No erosive arthritis is observed in
  IL-1?-deficient mice
• Spontaneous, destructive arthritis is observed in
  IL-1Ra-deficient mice

23
IL-1 Plays a Central Role in Cartilage Destruction
Chondrocyte death (NO, iNOS)
Proteoglycan synthesis (aggrecanase)
IL-1
Cartilage surface erosion(pannus, PMN)
Collagen damage( proMMP-13, type II collagen)
Immune complex deposits
iNOS inducible nitric oxide synthase MMP
matrix metalloprotease NO nitric oxide PMN
polymorphonuclear cell
Adapted from van den Berg W. Semin Arthritis
Rheum. 200130(suppl 2)7-16.
24
Erosive Arthritis Develops in the Complete
Absence of TNF
TNF-deficient mice with SCW-induced arthritis
SCW streptococcal cell wall
van den Berg W. Semin Arthritis Rheum.
200130(suppl 2)7-16.
25
IL-1 is Strictly Required for the Development of
Erosive Disease
IL-1b-deficient mice with SCW-induced arthritis
Control mice with SCW-induced arthritis
SCW streptococcal cell wall
van den Berg W. Semin Arthritis Rheum.
200130(suppl 2)7-16.
26
IL-1ra Reverses the Inhibition of Proteoglycan
Synthesis Induced by IL-1
400 300 200 100 0
rhIL-1 IL-1ra
rhIL-1 alone
Mean 35S-GAG (cpm/mg) ?SE
0 1 10 100 1000
rhIL-1 (pg/mL)
rhIL-1 recombinant human interleukin-1 IL-1ra
interleukin-1 receptor antagonist
Seckinger P, et al. Arthritis Rheum
1990331807-1814.
27
IL-1ra Prevents Cartilage Erosion
Antigen-Induced Arthritis
Markedly Reduced VDIPEN Expression at Day 5 in
IL-1ra-Treated Cartilage
Patella
Patella
VDIPEN
Femur
Femur
Control mice
IL-1ra-treated mice
VDIPEN expression indicates enzymatic cleavage of
proteoglycans IL-1ra IL-1 receptor antagonist
van den Berg W. Semin Arthritis Rheum.
200130(suppl 2)7-16.
28
Effects of IL-1b on Cartilage Remodelling

• IL-1? induces
• matrix metalloproteases
• aggrecanases
• nitric oxide

• IL-1? suppresses
• type II collagen synthesis
• aggrecan synthesis
• chondrocyte proliferation

IL-1? increases matrix degradation
IL-1? suppresses matrix synthesis
29
IL-1 is More Potent in Suppressing Cartilage
Proteoglycan Synthesis Than TNF
Differences in Cytokine Potency
Proteoglycan synthesis ()
Dose (ng/joint)
IL-1
TNF
IL-6

0.1
90

97
1
54
81
91
10
48
105
80
100
47
103
van de Loo F, et al. Arthritis Rheum.
199538164-172.
30
IL-1 is a Key Driver of Joint Inflammation and
Erosion
TNF- or IL-1-Deficient Mice
Animal model Inflammation
Destruction TNF IL-1 TNF IL-1 Antigen-
induced Collagen-induced
Immune complex SCW-induced

SCW streptococcal cell wall
van den Berg W. Semin Arthritis Rheum.
200130(suppl 2)7-16.
31
OPG-L and OPG Key Components of Bone Erosion

• Bone erosion is mediated by activated osteoclasts
• Osteoprotegerin ligand (OPG-L)
• induces osteoclast differentiation
• is crucial for osteoclast activation
• is identical to receptor activator of NF-?B
  ligand (RANK-L)
• is identical to osteoclast differentiating factor
  
• Osteoprotegerin (OPG) binds OPG-L, thus
  inhibiting bone resorption
• OPG-L/OPG balance determines relative degree of
  erosion

32
Cytokine Regulation of Osteoclast Differentiation
and Activation
Macrophage
Early osteoclast precursor
T Cell
Osteoclast precursor
X
TNF-a, IL-1
Synovial fibroblast
RANK ligand
OPG
PGE2
X
Osteoblasts
Osteoclasts
BONE
OPG osteoprotegerin PGE2 prostaglandin-E2
RANK receptor activator of NF-?B ligand
Dinarello C, Moldawer L. Proinflammatory and
Anti-inflammatory Cytokines in Rheumatoid
Arthritis A Primer for Clinicians. 3rd ed.
Thousand Oaks, Ca Amgen Inc. 2001.
33
IL-1? Increases Fas-Mediated Apoptosis of Human
Osteoblasts
Control IgM
Anti-Fas IgM
40

30
MG63 CellsWith Hypodiploid DNA ()
20
10
0
Control
IL-1?
IgM immunoglobulin M P lt0.01 vs control
anti-Fas
Adapted from Tsuboi M, et al. J Lab Clin Med.
1999134222-231.
34
Summary IL-1 Plays a Pivotal Role in RA and its
Cellular Effects may Be Counteracted by IL-1ra

• Inflammatory synovitis and rheumatoid joint
  destruction are mediated by an interdependent
  network of cytokines
• Experimental models of arthritis have shown that
  IL-1 plays a pivotal role in mediating
  inflammation and joint erosion
• In RA, disease activity correlates with levels of
  synovial and plasma IL-1
• RA patients show an imbalance between levels of
  IL-1 and IL-1 receptor antagonist (IL-1Ra)
• Antagonism of IL-1 by IL-1ra prevents or reduces
  severity of arthritis in animal models