ppt. on Cytokines and Chemokines in dermatology by Dr.MANMOHAN BAGRI. MD SKIN &VD (PG 1st year) MGMC&H,JAIPUR (RAJ).

1. CYTOKINES &
CHEMOKINES
Dr. MANMOHAN
MD(1st year) DVL
MGMC&H

2. CYTOKINES
Cytokines / Immunocytokines (greek: cyto-
cells, kines-movements)
Cytokines are low molecular weight(8-30 kd)
regulatory protein or glycoprotein secreted by white
blood cell and various other cells {including B and
T lymphocytes,macrophages, endothelial
cells,fibroblasts, mast cells and stromal cells of
spleen,thymus and bone marrow} in the body in
response to a number of stimuli.
The term cytokine -coined by COHEN in 1975.

3. Naming of cytokines
1.Monokines :- produced by
mononuclear phagocytes (monocytes)
2. Lymphokines :- produced by
activated T cell, primarily helper T cell.
3.Interleukins :- cytokines made by one
leukocyte and acting on other
leukocytes.
4.Chemokines :- cytokines with
chemotactic activities.

5. Cytokines can act in an……
Autocrine (same cell)..eg.IL-2
Paracrine (close proximity) eg.IL-7
Endocrine (long distance) eg.IL-1 & TNF

10. * Leukocyte function including
differentiation, growth activation and
migration.
* Cytokines are substantially
upregulated in response to injury to
allow a rapid & potent host response.
*It also play an important roles in the
development of the immune system
& homeostatic control of the immune
system under basal conditions.

11. Classification of cytokines
:-a) Primary and secondary cytokines
Primary :- those cytokines that can by themselves initiate
all the events required to bring about leukocyte
infiltration in tissues.
Eg:- 1) IL-1(both alfa & beta form)
2)Tumor necrosis factor(TNF include both TNF a & TNF b)
# IL-1 & TNF both able to induce cell adhesion molecule expression on
endothelial cells( selectins & immunoglobulin superfamily members as
:-intercellular adhesion molecule 1(ICAM-1) & vascular cellular
adhesion molecule 1(VCAM-1), to stimulate variety of cells to produce
a host of additional cytokines, & to induce expression of chemokines
that provide a chemotactic gradient allowing directed migration of
specific leukocyte subsets into a site of inflammation.
secondary :- those whose production is induced after
stimulation by IL-1 &/ or TNF family molecules,their
spectrum of activity is more restricted.

12. b)T-Cell subsets distinguished by
pattern of cytokines production
Two helper T-cell
subsets-Th1 and Th2.
Cytokines control
development of
specific CD4 helper T-
cell subsets.
Cytokine milieu at time
of activation of naïve
undifferentiated CD4
Tcell has profound
influence on ultimate
pattern of cytokines
secretion adopted by
fully differentiated
Tcell.

13. c)structural classification of
cytokinesClassical x-ray crystallography
technique, determined three
dimensional structure of
many cytokines.
Eg:-most of cytokines ligands
that bind to receptors of the
hematopoietin cytokines
receptor family are members
of four-helix bundle group of
proteins.
# Interferon-y(IFN-y) is four-
helix bundle cytokine that
exist as noncovalent dimer.
# TNF-a &TNF-b are both
trimers composed
exclusively of b-sheets
folded into a jelly roll
structural motif.
# ligand-induced trimerization
of receptors in TNF receptor
family is involved in initiation
of signaling.

14. Cytokines receptor families:-
 Five receptor families have been
recognised namely:-
 Interleukin 1 family-IL-1,IL-Ra,IL-18,IL-33
 Hematopoietin(class 1 cytokine)family-
IL-2,IL-3,IL-4,IL-5,IL-6,IL-7,IL-12,IL-
13,IL-15,IL-21,IL-23,GM-CSF, G-CSF
 Interferon(class 2 cytokine)family-IFN-a,
IFN-b,IFN-g,IL-10,IL-19,IL-20,IL-22
 Tumor necrosis factor family-TNF-a,TNF-
b,CD40L
 Chemokines-IL-8,CCL-19,CCL-
21,RANTES

15. Major families of cytokine
receptors

16. Cytokines of particular relevance
for cutaneous biology

17. Signal transduction pathways
shared by cytokines
 Cytokines use several downstream
pathways to mediate their effects - two
most important pathways-
 1)JAK-STAT pathway
 2)NF-kB pathway.
 other major signaling pathways are -
Ras; Erk MAP kinase; PI 3 kinase;
Phosphorylase C; IRS 1,&2; Src family
tyrosinase kinases, &
Sphingomyelinase ceramide pathways.

18. JAK/STAT PATHWAY:-
 1) JAK/STAT pathway was elucidated
through signalling initiated by IFN
receptors.
 2) play a role in signalling cytokines that
bind to members of the hematopoietin
receptor family.
 3) JAK/STAT PATHWAY
 operates through
 Sequential action of a family of four
nonreceptor tyrosine kinase and series of
latent cytosolic transcription factors known
as STATS(signal transducers and activators

19. 4) Cytoplasmic portion of many cytokine receptor
chains are noncovalently associated with one of
the four JAKS[jak1,jak2,jak3 and tyrosine kinase
2(TYK2)
5)The activity of JAK Kinase is upregulated after
stimulation of cytokines receptors.
Ligand
binding to cytokines receptors
leads to
association of two or more distinct cytokine receptor
subunit & bring the associated JAK Kinase into
close proximity with each other.
this promotes cross phosphorylation or
autophosphorylation reactions that fully activate the
kinase.

21.  NF-kB pathway
There are 84 key genes related to the NFκB-mediated
signal transduction.
 These include genes that encode members of the NFκB,
and IκB families, NFκB-responsive genes, extracellular
ligands, and receptors that activate the pathway, and the
kinases and transcription factors that propagate the signal.
 IL1, TNFα, IL17, and IL18, after using different cytokine
receptors and proximal signaling pathways, activate the
NFκB transcription factor and share the use of the NFκB
pathway.
 Stimuli that can activate the NFκB signal transduction
pathway are bacterial products, activators of protein
kinase, ultraviolet rays, viruses, and oxidants.
 The NFκB-mediated signal transduction plays a significant
role in inflammatory responses, apoptosis, viral replication,
autoimmune diseases, and tumor formation.

23. Cytokines that play an important
role in dermatology….
 Interleukin-1 receptor family(IL-1,IL-
18,IL-33)
 IL-1 is proinflammatory primary cytokine.
 It link innate and acquired immune systems to provide
synergistic host defence activites in skin.
 Two forms of IL-1:-IL-1a & IL-1b
 Both molecules present in cytoplasm of cells & have
mass of 31 kd.
 IL-1a is inherently,biologically active and present in cells
of body that are in contact with external environment.
 In skin-present in epithelial cells.
 When skin injured,keratinocytes releases IL-a & initiates
inflammation.

24.  IL-1b has to be cleaved by caspase-1
before it becomes biologically active.
 Produced by cells such as langerhans
cells,monocytes, macrophages.
 IL-1R1 is only signal transducing
receptor for IL—active forms of IL-1
bind with it to induce inflammation.
 IL-1ra(IL-1 receptor
antagonist)competes with IL-1 for
receptor binding to IL-1R and acts as
an antagonist to IL-1R ligand.

25.  The role of IL-1 in the koebner
phenomenon…..
 In response to any mechanical stress
or injury,keratinocytes release IL-
1,which cause release of ICAM-
1,VCAM-1, E-selectin & other
cytokines, which attract certain
memory T-cells bearing cutaneous
lymphocytes antigen(CLA) on their cell
surface.
 These memory cells present
abundantly in inflamed skin and are
attracted to any site of subsequent

26.  They immediately activated if they recognize
antigens present at site of inflammation causing
release of pro-inflammatory cytokines,which
magnify inflammatory response resulting in
koebner phenomenon.
 IL-18 produced by keratinocytes,langerhans cells
& monocytes.
 Specific receptor for IL-18 is IL-18R1.
 It acts on Th1 cells & NK cells,to induce their
proliferation and production of cytokines such as
IFNg.
 IL-33 is structurally closely related to IL-1b &
IL-18 , expressed in keratinocytes,monocytes
and mast cells.
 upregulated when these cells exposed to
proinflammatory stimuli.
 It stimulates NF-Kb & MAP kinases in responsive
cells,causing production of Th2 cytokines from
Tcells.

27. TUMOUR NECROSIS FACTOR
 Occurs in two forms- alpha,beta
 TNF along with IL-1 play critical role in initiation of
inflammatory response to infection and to
cancerous cells.
 They directly kill tumour cells
 Cause activation of other cells like
macrophages,monocytes to produce IL-1
 TNF activity is enhanced by INF-g
 In high concentration,TNF has some endocrine
function
 Production of fever(TNF acts as endogenous
pyrogen)
 Increased protein synthesis including acute phase
proteins in the liver

29.  Other cytokines…..
 Transforming growth factor(TGF-b)
 Named so because of the ability to transform fibroblasts
 It promotes wound healing by inducing fibroblast to increase
production of collagen.
 It descibes two polypeptide growth factors-TGFa & TGFb.
 TGFa produced by keratinocytes, macrophages & induces
epithelial development.
 TGFb is a protein that exists in 3 isoforms called TGF-b1
,TGF-b2,TGF-b3.
 TGF-b family is part of superfamily of 30 molecules-other
members include-
inhibin, activin, anti mullerian hormone, bone morphogenetic
protein, growth/differentiation factors.
TGF-b exert its effect through type-1 & type-2 cell surface
receptors with serine/threonine kinase activity.
 Leukemia inhibitory factor(LIF)
 Produced by T-cells,help in stem cell proliferation and
eosinophil chemotaxis.

30. Chemokine

31.  The discovery of the first chemoattractant
cytokine or chemotactic chemokine in
1977.
 Chemokines are low molecular weight (8-
11 kDa)basic polypeptides.
 Main function to attract and activate
leukocytes.
 Chemokines play important role in
angiogenesis , neural development ,
cancer metastasis , hematopoiesis &
infection.

32.  Proteins are classified into the
chemokine family based on their
structural characteristics, not just their
ability to attract cells.
 All chemokines are small, with
a molecular mass of between 8 and
10 kDa.
 They are approximately 20-50%
identical to each other; that is, they
share gene sequence and amino
acid sequence homology.

33. Structure of chemokines
*Chemokines grouped into
4 subfamilies based on
spacing between first
two amino terminal
cysteines.
a)C-X-C eg.IL-8
b)C-C eg.RANTES,MCP-
1,MIP-1
c)C27(X-C)
eg.Lymphotactin
d)C-X3-C eg.fractalkine
*CXC chemokines/a-
chemokines show a c-x-
c motif with one non
conserved amino acid
between two cysteins.

34.  They all also possess conserved amino
acids that are important for creating their 3-
dimensional or tertiary structure, such as (in
most cases) four cysteines that interact with
each other in pairs to create a Greek
key shape that is a characteristic of
chemokines.
 Typical chemokine proteins are produced
as pro-peptides, beginning with a signal
peptide of approximately 20 amino acids
that gets cleaved from the active (mature)
portion of the molecule during the process
of its secretion from the cell.

35.  Intramolecular disulfi
de bonds typically join
the first to third, and
the second to fourth
cysteine residues,
numbered as they
appear in the protein
sequence of the
chemokine.
The first two cysteines, in a
chemokine, are situated close
together near the N-terminal
end of the mature protein, with
the third cysteine residing in the
centre of the molecule and the
fourth close to the C-terminal
end.

36.  A loop of approximately
ten amino acids follows
the first two cysteines
and is known as the N-
loop.
 This is followed by a
single-turn helix, called
a 30s loop, three β-
sheets and a C-
terminal α-helix.
 These helixes and
strands are connected
by turns
called 30s, 40s and 50s
loops, the third and
fourth cysteines are

37. *other major subfamily
of chemokines called
b-chemokines lacks
additional amino acid
and is termed CC
subfamily.
*C subfamily
represented by
lymphotactin,and
fractalkine is only
member of CXXXC(or
CX3C)subfamily.
*chemokines assigned
to one of two broad &
perhapes overlapping
functional groups.

38. *one group [eg.regulated on activation normal
T-cell expressed and secreted
(RANTES),macrophage inflammatory
protein 1a/b, Liver and activation-regulated
chemokines(LARC)] mediates attraction &
recruitment of immune cells to sites of
active inflammation.
*other group [eg.secondary lymphoid-organ
chemokines(SLC) & stromal cell-derived
factor-1(SDF-1)] appear to play role in
constitute or homeostatic pathways.

39.  IL-8 is typical C-X-C chemokines which
mainly act on neutrophils & minimal activity
on monocytes,eosinophils.
 C-C chemokines include monocyte
chemoattractant protein(MCP-1),
eotaxin,macrophage inflammatory protein-
1a(MIP-1a) and RANTES(regulated and
normal T cell expressed and secreted)

 Which attract monocyte, eosinophil,
basophils, & lymphocytes but not
neutrophils.
 Lymphotactin is C type chemokine with
specific action on lymphocytes.

40.  C-X3-C causes chemotaxis of T
lymphocytes and monocytes.
 Chemokines cause chemotaxis by
converting adherence molecules,VLA-4, &
LFA-1integrins present on rolling leukocytes
to a high affinity state.
 allows rolling leukocytes to bind to
endothelial cells.
 Chemokines stimulates migration of
leukocytes across vessel wall.
 RANTES is potent chemokine induce
granular release & leukotriene synthesis in
basophils & eosinophils, & histamine
release.

41.  CCL27-CCR10 interaction regulates
memory T cell recruitment to skin &
allergic responses.
 CCL18 & CCL1 expression is
increased in atopic skin, psoriasis &
cutaneous lupus erythematosus.

42. Chemokines receptor in skin
biology

43. Chemokines and cutaneous
leukocyte trafficking
 Chemokines play at least 3 different roles:-
 1)they provide signal required to cause
leukocytes to come to a complete stop in a
blood vessel at inflammed site.
 2)transmigration of leukocyte from lumenal
side of blood vessel to the ablumenal side.
 3)chemokines attract leukocytes to the site of
inflammation in dermis or epidermis after
transmigration.
 In addition chemokines & their receptors are
known to play critical role in emigration of
resident skin dendritic cell from skin to
draining lymphnode.

45. Chemokine in disease

46. Atopic dermatitis
 Is a prototypical Th-2 mediated allergic skin
disease with multifactorial genetic and
environmental factor.
 Role of CCR4 &CCR10 in atopic dermatitis
.
 TARC / CCL17 may play a role in recrutting
T cells to atopic skin .
 In patients with atrophic dermatitis CLA,
CCR4, CCR10 lymphocytes were increased
in peripheral blood .
 Serum level of TARC / CCL17 and CCL18,
CCL27 increased higher.

47.  CCL18 is produced by antigen
presenting cells & attracts CLA memory T
cells to the skin.
 The production of ectoxin & CCR3 may
contribute to the recruitment of
eosinophilis and TH2 lymphocytes in
addition to stimulating keratinocyte
proliferation .

48. Psoriasis
 Psoriasis is characterized by hyperplasia of
the epidermis ( acanthosis ) & prominent
dermal & epidermal inflammatory infiltrate ,
typically resulting in thickened
hyperkeratotic plaques .
 Psoriasis is a classical TH-1 associated
disease .
 TH17 cells their signature effector cytokine
IL-17& IL-22 , IL-23 are major growth &
differentiation factor for TH17 cells are
abundant in psoritic skin lesions.
 CCR6 and CCL20 important mediator of

50. Cancer
 Play a role in tumor formation &
immunity including the control of
angiogenesis & induction of tumor
immune response .
 Melanoma secrete chemokines that can
attract leukocytes .
 Breast cancer secrete macrophage
chemotatic protein ( MCP-1) chemokine
that attracts macrophages through
CCR2 increased level of MCP -1 which
increases number of macrophages with

51.  Chemokines secreted by tumor cells do
lead to recruitment of immune cells this
does not necessarily lead to increased
clearance of tumor .
 Macrophages play critical role in cancer
invasion & metastasis . MCP -1 increased
expression of macrophages . IL-4 through
an autocrine feedback loop & skew the
immune response from Th1 to Th2
 Skin cancer such as melanoma specific
sites such as brain , lung , liver , skin sites .
 Human breast cancer as well as melanoma
lines express he CXCR4 ligand CXCL12
which stimulates tumor growth as well as
angiogenesis .

53. Infectious diseases
 Microorganisms express chemokine
receptors like US28 by cytomegalovirus
& kaposi ‘s sarcoma herpes virus
GPCR(G protein coupled receptor) or
human herpes virus 8.
 This receptor bind to several
chemokines & remain active & works as
growth promoter in kaposi sarcoma.

54. References:-
 1) Fitzpatrick’s dermatology in general
medicine (seventh edition)
 2)Iadvl textbook of dermatology (fourth
edition)
 3)CME article- cytokines in
dermatology-a basic overview—Arijit
coondoo.