Cytokines and signaling pathways inhealthy and disease

DENT516

Ge Jin, Ph.D.Email: ge.jin@case.eduPhone: 3683791Office: DO3570, School of Dental Medicine

March 26, 2012

Learning Objectives:

1. What are cytokines?

2. understand that NFB and STAT proteins are transcription factors that modulate immune responses

3. understand that cytokines play important roles in PD

Immune cells and the mediators they produce

Cytokines

small, secreted, non-antibody proteins

produced by cells involved in both innate & adaptive immunity

mediate and regulate immunity, inflammation, and hematopoiesis

Cytokines Lymphokine: made by activated lymphocytes, especially TH cells, e.g. IL-2

Monokine: made by mononuclear phagocytes, e.g. Mig/CXCL9

Chemokine: chemotactic activity, e.g. IL-8, CXCL12

Interleukin: interaction between leukocytes IL-1, IL-8, IL-10, IL-13……

named by activity: Tumor Necrosis Factor (TNF), Colony Stimulation Factor (CSF), Transforming Growth Factor (TGF)….

Properties of Cytokines

produced in response to immune stimuli -- not store pre-formed -- synthesis: DNA mRNA protein secretion -- slow cellular response

can act on the cells that produce them (autocrine action)

can act on nearby cells (paracrine action)

can act on distance cells (endocrine action)

Properties of Cytokines

can be produced by many cell types and act on many cell types (pleiotropic)

different cytokines can have similar actions (redundant)

Properties of Cytokines

can modulate synthesis of other cytokines - cascades: e.g. TNF IL-1 IL-6, IL-8…

- enhance or suppress production of other cytokines: positive or negative

influence the action of other cytokines - antagonistic - additive - synergistic

short half life, low plasma concentration, bind to receptor with high affinity

Immunoglobulin superfamily: IL1R, TLRs…

Cytokine Receptors(grouped by structures into families)

Toll-IL-1 Receptordomain (TIR)

Toll-likereceptors (TLRs)

leucine-richrepeatsimmunoglobulin

domain

IL-1 receptor

cell membrane

TNFR family: TNF, FasL, CD40L…

Cytokine Receptors

Cytokine ReceptorsG

M-C

SF

R

IL-3

R

IL-5

R

GM-CSF

IL-2

IL-3 IL-5

IL-15 IL-7 IL-9

IL-2

R

IL-2

IL-1

5R

IL-2

IL-7

R

IL-9

R

class I receptor family: hematopoietin family

gp130gp130 gp130 gp130

CN

TF

R

cell membrane cell membrane

GM-CSF: Granulocyte macrophage colony-stimulating factorIL: interleukingp130: glycoprotein 130 (m.w. 130 kDa)

IL-6 IL-11

CNTF LIF/OSM

-- share receptors

-- defect in a unique cytokine have little effect

-- defect in a share component (common receptor) can have profound effects

e.g. IL-2R defect X- linked SCID

(Severe Combined Immunodeficiency)

class II receptor family: Interferon , , and

Cytokine Receptors

IFNARI

IFNAR2c

IFNAR2b

IFNR

IFNR

type I IFN receptor type II IFN receptor

cell membrane

type I IFN: IFN and IFN, type II: IFN

chemokine receptor family: CCR1-5, CXCR1-4

NH3

COOH

binding of a ligandto the receptor

Cytokine Receptors

cell membrane

chemokine receptor family: CCR1-5, CXCR1-4G-Protein-Coupled Receptor (GPCR)

Cytokine Signalingcytokines

membrane receptors

phosphorylation cascades

gene transcription, Ca++ influx…

signal transduction

binding

activation

Cytokine Signaling

NFB signaling pathways

JAK/STAT signaling pathways

Chemokine/GPCR signaling pathways

Cross-talk between pathways

NFB Signaling

NFB signaling inducers: cytokines: IL-1, TNF,… microbial cell components: Fn cell wall, lipopolysacchrides (LPS),… virus: retroviruses, double-stranded RNA (dsRNA),…

Receptors: IL-1 receptors Toll-like receptors (TLRs, innate immunity) TNF receptors

Nuclear Factor B (NFB): dimeric transcription factors: p65/RelA, c-Rel, RelB, p105/p50, p100/p52 sequestered by inhibitory IB proteins and retained in cytosol in resting cells

NFB

IRAK

TRAF6pp

IRAK

4

pellino1

IB

IBp

p

TF

IRAK pp

p

p

u

u

degradation

u

TAK1

TAK1

activ

atio

n

uu u

u

pp IBIB

ubiquitination&degradation

uu TRAF6

pTAK1

TAB1

TAB3

TAB2Ubc13/Uev1A

complex III

IRAK

TRAF6pp

IRA

K4

pe

llin

o1

TAK1

TAB1

TAB3TAB2

p

complex II

NEMO

IKKIKK

pIK

Kac

tivat

ion

p

u ubiquitination

phosphorylation

IL-1 receptor

IRAK

Tollip MyD88

IRAK4

TRAF6pp

complex I

IL-1

nucleus

cell

mem

bran

e

TNFaIL-6IL-8hBD-2….

innate&adaptiveimmunity

p

NFB

activ

atio

n

NFB p

nucl

ear

trans

loca

tion

pTF NFB p

JAK/STAT Signaling Pathway

JAK (Janus Kinases): a family of tyrosine kinases, JAK1-3, Tyk2

STAT (Signal Transducers and Activators of Transcription): transcription factors, STAT1-6,…

Cytokines: IFN/, IFN-, Epo, GM-CSF, IL-6, IL-13…

in resting cells, non-phosphorylated, monomeric STATs reside in cytoplasm.

SJ Baker et al, Oncogene (2007) 26, 6724–6737.

cdc25a, cyclin D1~3,c-myc, cyclin E, MMP9p21, caspase 3, 1, 8…

Chemokine Signaling

2 major families: the CCL (C-C motif ligand) family and CXCL (C-x-C motif ligand) family

CCL1~27, CXCL1~14

receptors: G-protein coupled 7 transmembrane receptor (GPCR)

Gi

SDF

PI-3K MAPK PLC

target genes

Adhesion, polarization, chemotaxis

CCL12 (SDF) signaling

p

p GRK-arrestin

recyclingdegradation

SDF

pathogens/infectionbacteria, virus

inflammationchemokine production, recruitment of phagocytes….

increased blood supply, capillary permeability, leukocyte migration

killing of pathogensneutralizing toxins, limiting pathogen spread

tissue repairphagocytosis of debris, pathogens, dead cells; cells growth

resolutionelimination of a pathogen, disappearance of leukocytes, full

regeneration of tissue function

Failure of acute inflammation resolution leads to chronic inflammation and autoimmune disorders

Examples: periodontal diseases (PD)chronic inflammation after dental treatment

Cytokines and Periodontal Diseases (PD)

the most common diseases in the world and the leading cause of tooth loss, a chronic infection that slowly attacks and destroys the gums and bone that support the teeth.

• caused by bacterial (~200 species) infection

• followed by a persistent immune response

• resulted in tissue damage

bacteriaA. actinomycetemcomitans, P. gingivalis, B. forsythus, T.

denticola, T. socranskii, P. intermedia

cell wall components(lipopolysaccharides, LPS)

exotoxins hydrolytic enzymes

inhibit antimicrobial peptides (lysozymes) activity

toxic to phagocytes (macrophages)

tissue damage/bone resorption

stimulate cytokine production of immune cells/chronic inflammation

Bacteria

LPS, exotoxin, etc.

binding to Toll-like receptors (TLRs)

activation of the NFkB signaling pathway in immune cells and epithelial cells

TNF, IL-1, IL-6, IL-8, IFN/, chemokines…perodontitis(autoimmune disorder)

neutrophilsmacrophages

dendritic cells(DCs)

T cellsB cells

phagocytosisH2O2, NOAMP

Tumor Necrosis Factor (TNF) produced by activated macrophages and T cells most important mediator of acute inflammation in response to microbes, such as LPS produced by the LPS-membrane bound Toll-like receptors

(TLRs) mediates recruitment of neutrophils and microphages to site of inflammation stimulates endothelial cells and macrophages to produce chemokines a potent pyrogen causing fever by direct action or via IL-1 promotes production of acute phase proteins, such as CRP roles in rheumatoid arthritis, psoriasis, tuberculosis, …

TNF and PD

• high in diseased periodontal tissues

• influences leukocyte migration

• corrected with RANKL and matrix metalloproteinase (MM) production

• stimulates IL-1, IL-8, IL-6 proinflammatory cytokine production

central role in inflammatory reaction, alveolar bone resorption, and the loss of connective tissue attachment

Interleukin 1 (IL-1)

Produced by activated macrophages, stimulated lymphocytes, keratinocytes, fibroblasts Activates the NFB signaling pathway (similar effects to TNF) Helps activate T cells Can be induced by inflammation, injury, and infection

Summary (PD and cytokines)

TNF and IL-1 play critical roles in amplifying the inflammatory response, leading to production of lytic enzymes and proinflammatory cytokines in PDs.

TNF and IL-1 antagonists block the progression of the inflammatory cell infiltrate and prevent the periodontal lesions

Cytokinesproperties, categories, signaling, function

What are cytokine?Interleukines, chemokines, monokines, …cytokine receptorsNFkB, JAK/STATA, chemokine signaling pathwaysrole of cytokines in immunomodulationcytokines and oral diseases (PD)