Cytokines

Cytokines

• small secreted proteins

• they mediate and regulate

immunity, inflammation, and

hematopoiesis.

Cytokines

• Cytokines - heterogenous group of

polypeptides → acting on distinct cell

populations → coordination and

amplification of immune responses

• many cytokines exhibit many functions

• activity of some cytokines is overlapping

(IL-4 a IL-13)

cytokines act

• autocrine (IL-2)

• paracrine (IL-4, IFN-γ, IL-10, TGF-β)

• endocrine (IL-1, IL-6, TNF-α)

pleiotropy of cytokines

• one cytokine exerts multiple actions

• one cytokine interacts with several receptors (chemokines)

• affects the activity of multiple cell types

cytokines and their receptors -

high redundancy

• shared biological actions

• many cytokines interact with single receptors

• many receptor forms can exist for a single cytokine

• promiscuity of receptors

Synergy and antagonism

Cytokines

• activation and inhibition (IFN-γ, IL-10, IL-4, TGF-β)

• stimulation of proliferation (IL-2, IL-7, GM-CSF)

• induction of differentiation (IL-3, IL-4, IL-5, IL-6, RANK-L)

• enhance resistance to viruses (IFN-I)

• antitumor effect (oncostatin, TNF-β)

• co-stimulation (B7.1, B7.2, 4-1BB, OX40, BAFF, APRIL)

• endothelial cell activation (TNF-α, TNF-β, IL-17)

Cytokines - classification

1. lymphokine (cytokines made by lymphocytes)

2. monokine (cytokines made by monocytes)

3. interleukin (cytokines made by one leukocyte

and acting on other leukocytes)

4. chemokine (cytokines with chemotactic

activities)

Receptor-based cytokine classification

• Class I cytokines

• (IL-2, IL-15, IL-4, IL-13, IL-7, IL-9, IL-21; IL-3, IL-5,

GM-CSF; IL-6, IL-11, IL-27, OSM, LIF; Epo, G-CSF;

IL-1, IL-18, IL-33; IL-12, IL-23, IL-27; IL-16)

• Class II cytokines

• Interferons (IFN-I, IFN-γ)

• IL-10 (IL-10, IL-22, IL-28)

• Imunoglobulin family (B7.1, B7.2)

• TNF family (TNF-α, TNF-β, CD40L, FasL, CD27L,

CD30L, 4-1BBL, OX40L, RANKL, APRIL, BAFF)

• IL-17 family (IL-17, IL-25)

Cells producing

cytokines

Innate immunity Macrophages

Endothelial cells

Epithelial cells

Fibroblasts

Specific immunity T, B lymfocytes

Macrophages

NK cells

Hematopoesis

SCF (Stem cell factor)

GM-CSF (Granulocyte-macrophage colony-stimulating factor)

IL-3

IL-5

IL-7

Th1 – Th2

subsets

Th1 immune response: IL-2, IL-12, IFN

gamma a TNF

Th2 immune response: IL-4, IL-5, IL-13

Sakaguchi et al Cell 2008

Tregs

Distinct function of interferons

•IFN-β

•regulation of nonspecific humoral responses and responses to

viral infections and tumor development

•induces negative immune regulating molecules IL-10, PD-L1

which suppress T cell responses

•IFN-α

•antiviral, antiparasitic, and antiproliferative activities

•IFN-γ

•inhibits growth of B-cells induced by IL-4

•growth-promoting factor for T cells

•induces secretion of TNF-α in monocytes and MФ

•in MФ stimulates release of ROS, antiviral and antiparasitic activities

•inhibits proliferation of normal and transformed cells

The molecular basis of interferon action

Inhibition of virus RNA

replication

Inhibition of expression of

virus receptors

Induction of lytic activity of

NK cells

Cytokines are sensed by receptors

Cytokines are sensed by receptors

Receptors -signaling

Viral mimics of cytokines and receptors

Chemokines

Chemokines

• a group of molecules which function in

the recruitment and activation of

leukocytes and other cells at sites of

inflammation, possess the properties of

both chemo attractants and cytokines

• other functions (tissue remodeling,

mucin production etc.)

Many functions of chemokines

Li, 2004, 1(2) Cellular & Molecular Immunology

Chemotaxis

Chemokines • chemokines small proteins (8 – 15 kDa)

• families CCL, CXCL, CX3CL, XCL and number (CCL1, CXCL1, CX3CL1,

XCL1), in the text CXC chemokines

• receptors are designated as CCR, CXCR, CX3CR, XCR and number (CCR1,

CXCR1, CX3CR1, XCR1)

• CC chemokines → 28 members

• CXC chemokines → 16 members

• CX3C chemokin → 1 member

• XC chemokines → 2 members

• receptors → 20 members

Chemokine receptors and ligands

Expression on all cells

Interaction of chemokine - receptor

Ono et al, 2003, 111 J Allergy Clin Immunol

chemokine

receptor

Signalization of chemokines

• GPCR – G-protein-coupled receptor

Endothel-fixed chemokines activate

leukocytes transmigration

Ransohoff, 2009, 31 Immunity

By acting of membrane bound chemokines integrins

are activates → enhanced affinity and avidity →

extravasation

Neutrophiles change their morphology after exposing to

chemoattractant (EM)

Baggiolini, 1998 392(9) Nature

Other chemotactic molecules • C3a, C5a complement components

• leukotrien B4

• PAF (platelet-activating factor)

• expressed by platelets, endothelial cells, neutrophils,

monocytes, and macrophages

• platelets aggregation

• inflammation

• anaphylaxis

• activates β2 integrin

• bacterial factors

Von Adrian et al, 2003, 3 Nature reviews Immunology

Regulatory role of chemokin-like molecules

• DARC (Duffy antigen receptor for chemokines), D6, CCXCKR,

CCRL2, CXCR7

• are not GPCR, do not induce changes in intracellular Ca+

• internalize extravasal chemokines to be presented on luminal part

of endothelium

• on erythrocytes surface DARC allow entrapment of surrounding

chemokines and thus regulate their activity

• effect detectable after blood transfusion → loss of DARC’s

scavenging activity on banked erythrocytes → posttransplantation

pneumonia

Ransohoff, 2009, 31 Immunity

Regulatory role of chemokine receptor-like molecules (D6)

Chemokines in therapy

• Allosteric antagonist of CCR5 (Maraviroc)

• inhibition of HIV-1 infection

• CXCR4 partial agonist (Mozobil, AMD3100)

• originally for HIV-1 infection

• approved for hematopoietic stem cell mobilization

• Antagonist of CCR9 (CCX-282, Traficet-EN)

• IBD, Crohn diseas, celiac disease therapy ???????

Adhesion

molecules

Adhesion molecules

• adhesion molecules are involved in cell-to-cell and cell-

to-matrix interactions

• immunologically competent cells use:

• during all intercellular contacts – activation,

inhibition, survival

• for targeted migration across endothelial layer

• for targeted migration to and resting in individual

immunologically important sites

• some microorganisms utilize for adhesion to target cells

(HIV utilizes α4β7 on T cells for transport to lamina

propria mucosae)

Adhesion molecules

1. addressins → glycan components O- and N-linked to

protein backbone, recognized by selectins

2. selectins → bind glycan moiety of extracellular matrix

or membrane glycoproteins (addressins)

3. integrins → bind CAM, extracellular matrix, fibrinogen

4. immunoglobulin molecules ICAM → ligands for β2, β4,

and some β1 integrins, glycan moiety of CAMs serve

as some addressins

Adhesion molecules - four classes

Leukocyte migration

Lymphocyte migration to LN

Lymphocyte migration to LN

Von Adrian et al, 2003, 3 Nature reviews Immunology

Neutrophils migration to inflammed tissues

Addressins

Lewis – terminal oligosaccharides Symbol Structure Note

Lea Galβ1-3(Fucα1-4)GlcNAc-R blood group antigen

organogenesis

Leb Fucα1-2Galβ1-3(Fucα1-4)GlcNAc-R blood group antigen

organogenesis

Sialyl-Lea NeuAcα2-3Galβ1-3(Fucα1-4)GlcNAc-R binds E-selectin

Lex Galβ1-4(Fucα1-3)GlcNAc-R blood group antigen

organogenesis

Ley Fucα1-2Galβ1-4(Fucα1-3)GlcNAc-R blood group antigen

organogenesis

Sialyl-Lex NeuAcα2-3Galβ1-4(Fucα1-3)GlcNAc-R binds L- E-selectin

Sulfo sialyl-Lex high affinity binding

to E-selektin

Selectins

Naive T cell migration to LN

Mature T cell – cell interaction

integrin old names expressed on ligand functions

α1β1 VLA-1,

CD49a/CD29 activated T cells

collagen, laminin

contact with extracellular

matrix

α2β1 VLA-2, GPIa

CD49b/CD29

B cells, platelets

monocytes, collagen, laminin

contact with extracellular

matrix

α3β1 VLA-3,

CD49c/CD29

B ly,

adherent cells

collagen, laminin,

entaktin, invazin

contact with extracellular

matrix

α4β1 VLA-4,

CD49d/CD29

B ly, thymocytes,

monocytes,

granulocytes, DC

fibronectin

MAdCAM-1,

VCAM-1

contact with extracellular

matrix,

nosal mucosa

αLβ2 LFA-1 leukocytes ICAM-1, 2, 3 leukocyte integrins

αMβ2 CR3, MAC-1

CD11b/CD18

myeloid cells

NK

ICAM-1, 2, 3

iC3b, fibrinogen

LPS, β-glucans

leukocyte integrins

αXβ2 CR4, p150

CD11c/CD18

myeloid cells

DC

ICAM-1,

fibrinogen leukocyte integrins

αIIβ3 gp IIb/IIa

CD41/CD61 platelets

fibrinogen,

fibronectin

platelets entrapment in the

site of injury

αVβ3 vintronectin

CD51/CD61

endotelie,

platelets,

fibroblasty

fibrinogen,

fibronectin

platelets entrapment in the

site of injury

α4β7 LPAM-1 T cells VCAM-1

MAdCAM-1

homing to mucosal tissue

of GIT, respiratory tract

αEβ7 HML-1 interstic. T cells E-cadherin targeting to epithelia

Integrins

Immunoglobulin superfamily CAM

Various differentiation stages are

associated with different AM

expression

APC - T cells interaction

APC - T cells interaction

Targeted anti-cytokine therapy

Mechanismus:

1) Antigonists of cytokine

receptors (IL-1 receptor

antagonist IL-1Ra)

2) Soluble cytokine receptors

3) Anti-cytokine antibodies

anti-TNF antibodies

(Infliximab-antibody,

Etanercept-circulating receptor)

•reumatoid arthritis

•Crohn disease

•sarcoidosis

•autoimune and inflammatory diseases

Reumatoid arthritis

Increased

inflammation

Increased production

of MMP

Increased cytokine

production (IL-1, IL-6)

Increased adhesion

molecules

Cell migration

into joints

Tissue

remodeling

B cell

Macrophage

T cell

Synoviocyte

Cytokines

TNFa

RF

Autoantibodies

Activates

Activates Activates Inflammation

Joint damage

B B

T

T T

T

FLS

PC

PC

FLS

MΦ MΦ

T T

APC/DC

Mechanismus of Etanercept

action

Etanercept

X

Cytokines

Cell – cell communication

Stimulus - Cytokin – Receptor - binding – effect

Promiscuity, redundancy, synergy, networks

In health and disease

Targeted biological therapy