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CytokineCytokine--Mediated Inflammation in IBDMediated Inflammation in IBD

Theresa T. PizarroTheresa T. Pizarro

Department of Pathology, Case Western Reserve University

Andoh, et al., 2008

Mucosal Cytokine Network in IBD

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Adapted from Pizarro and Cominelli , J Immunol 2007

Cytokine group of ligands and receptors related by mechanisms of origin,receptor structure and common signal transduction pathways

Common Name IL-1 Family Name FunctionLigand-Binding

Chain

IL-1α IL-1F1 Agonist IL-1R type IIL-1β IL-1F2 Agonist IL-1R type IIL-1ra IL-1F3 Antagonist IL-1R type IIL-18 IL-1F4 Agonist IL-18R

IL-1F5 Agonist IL-1Rrp2IL-1F6 Agonist IL-1Rrp2IL-1F7 Unknown IL-18R IL-1F8 Agonist IL-1Rrp2IL-1F9 Agonist IL-1Rrp2

IL-1F10 Unknown UnknownIL-33 IL-1F11 Agonist ST2

Interleukin-1 (IL-1) Family

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Charles receives Crafoord Prize from the Royal Swedish National Academy ofSciences awarded by King Carl Gustaf of Sweden, May 11, 2009

• 2009 Albany Medical Center Prize in Medicine and Biomedical Research• 2010 Paul Ehrlich and Ludwig Darmstaedter Prize in the Field of Medicine

from the Federal Republic of Germany

IL-1 family members are synthesized as propeptides and are cleaved into theirmature forms by caspase-1, which is activated by the inflammasome

Franchi L, Nat Immunol 2009

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Cominelli et al., J Clin Invest 1990

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Casini-Raggi et al., J Immunol 1995

Carter et al., Gut 2001

Pizarro et al., J Immunol 1999

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Pizarro et al., J Imunol 1999

Corbaz et al., J Immunol 2002

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• Interleukin-33 (IL-33) is a novel cytokine,recently recognized as an Interleukin-1family member (Schmitz J, Immunity 2005)

• Expression of IL-33 has been shown inseveral types of cells, both haematopoietic(macrophages, DCs) and non-haematopoietic (fibroblasts, adipocytes,SMCs, ECs, IECs) (Schmitz J, Immunity2005)

• IL-33 is the ligand of the ST2 receptor,which is expressed by Th2 lymphocytesand mast cells, as well as fibroblasts andepithelial cells (Lohning M, PNAS 1998; XuD, J Exp Med 1998; Tago K, BiochemBiophys Res Commun 2001)

* Adapted from Schmitz J, Immunity 2005

§ Adapted from Arend WP, Immunol Rev 2008

Interleukin-33

*

§

IL-33 isoforms

Luthi et al., Immunity 2009

IL-33 was initially thought to be activated by the inflammasome throughcaspase-1 cleavage of a full-length form (30 kDa) in to an active form, similarlyto other IL-1 family members, recently it has been demonstrated that :

1) full-length IL-33 is the most bioactive form

2) Caspase-1 activation does not occur during physiological conditions

3) Pro-apoptotic caspases (-3 and -7) cleave IL-33 into less active 20-22 kDa forms

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Role of IL-33 as an “alarmin”

§ Carriere V, PNAS 2007; * Moussion C, PLoS ONE 2008

*

• Full-length IL-33 contains a nuclear localization sequence and a DNA-bindingdomain§; constitutively localized to the nucleus of endothelial and epithelialcells*

• No clear data regarding lL-33mechanism of secretion isavalaible; proposed release bysuffering/dying cells, acting as anovel alarmin*

• Thus, most bioactive IL-33 form(full length) may be releasedduring necrosis, and processedinto less potent, cleaved IL-33during apoptosis

ST2L

sST2

* Arend WP, Immunol Rev 2008

• IL-33: ligand for ST2 receptor; belongs to the Toll/IL-1R (TIR) superfamily

• ST2: expressed by Th2 lymphocytes and mast cells, as well as fibroblasts and epithelial cells

• 2 different splice variants of ST2 have been described:

- ST2L, localized to cell membrane

- sST2, soluble form functioning as decoy receptor

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•Kakkar et al., Nat Rev Drug Discov 2008•§ Ali et al., PNAS 2007

ST2L IL-1RAcP

IL-33

• ST2L requires the presence of IL-1RAcP in order to initiates the signaling cascade§

MyD88

• IL-33/ST2 signaling pathway involves MyD88, p38, JNK, NF-κB and AP-1*

NF-κB / AP-1

p38

• IL-33 induces Th2 cytokine production and potentiates both Th1 and Th2 responses

• exposure to IL-33 in the gut causes epithelial hyperplasia, neutrophil and eosinophil infiltration

• However, to date, no data regarding IL-33 and ST2 expression and role in IBD are available

* Adapted from Kakkar R, Nat Rev Drug Discov 2008

§ Adapted from Schmitz J, Immunity 2005

Potential role for IL-33 in the gut

PBS

IL-33

*

§

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Features of the SAMP1/YitFc (SAMP) mouse model of experimental Crohn’s disease

n Spontaneous ileitis without chemical, genetic or immunologic manipulation

n 100% penetrance by 12 wks; persistence of phenotype up to 80 wks of age

n Closely resembles human CD for disease location and histologic features

n Disease mediated by both Th1 and Th2 cytokines

n Responsive to standard CD therapies (i.e. steroids, anti-TNF)

n Earliest changes are characterized by epithelial cell alterations

Full-length IL-33 and sST2 are increased in UC inflamed mucosa

A

B

Pastorelli et al. submitted

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UC UC IEC

UC LPMC

CD

CONT

UC NEG

IL-33 is localized to IEC and LPMC in the inflamed mucosa of UC patients

Pastorelli et al. submitted

UC

UC IEC

UC NEG

CD

CONT CONT IEC

Immunolocalization of ST2 is altered in intestinal tissue from UC patients

Pastorelli et al. submitted

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Differential ST2 expression in epithelium of UC vs. inflammatory control patients

DIV

INF COLUC

Pastorelli et al. submitted

A

B

0

1

2

N=18 N=10 N=7

P<0.05

Re

lativ

e S

T2

mR

NA

ex

pre

ssio

n

0

8

16

N=18 N=10 N=7

P<0.05

P<0.05

Rel

ativ

e IL

-33

mR

NA

ex

pre

ss

ion

IL-33 expression is increased and ST2L is downregulatedin IEC from UC patients

Pastorelli et al. submitted

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0

500

1000

1500

2000

2500 P<0.001

N=59 N=72 N=19

SLD =5 pg/ml

P<0.01

IL-3

3 se

rum

lev

els

(pg

/ml)

0

200

400

600

800

1000

N=59 N=72 N=19

SLD =32 pg/m l

P<0.05

P<0.05

sST

2 se

rum

lev

els

(pg

/ml)

0

2

4

6

8

10

N=57 N=71 N=19

P<0.05

IL-3

3/sS

T2

Rat

io

B

A

IL-33 and sST2 serum levels are significantly increased in IBD patients and cleaved IL-33 is the main circulating form

Pastorelli et al. submitted

•Luca Pastorelli•Rekha Rani Garg•Benedetta Mattioli•Sharon Hoang•Xiao Ming Wang

ACKNOWLEDGEMENTSACKNOWLEDGEMENTS

•• Maurizio VecchiMaurizio VecchiUniversity of MilanoUniversity of Milano

•• Claudio FiocchiClaudio FiocchiCleveland Clinic FoundationCleveland Clinic Foundation

•• Fabio CominelliFabio CominelliCWRUCWRU