Download TH1 CYTOKINES - WordPress.com

IMMUNITY AND INFLAMMATION-Basic concepts
PART-1 & 2
In Relation To Dentistry
OPSONIZATION



It is the process of coating a particle with recognizable
molecules to enable phagocytic ingestion.
Immune system develops antibodies against infectious
agents; these antibodies adhere to the bacterial
membrane and make them susceptible for
phagocytosis.
Complement can also attach to some bacteria even in
the absence of antibodies and this leads to
opsonization.
opsonization






3 types of opsonins are
1.Complement metabolite ic3b
2. IgG
3. Both
C3 receptors: There are 3 products of C3 that bind
to membrane of target cells (or) (called opsonin
fragments). They are C3b, Ic3b, C3dg. Four
receptors for these fragments are known
CR (complement receptors) CR1, CR2, CR3, CR4.
IgG:
They have surface receptors collectively
known as Fc receptors.
3 types :
Fcr RI high affinity (macrophages)
Fcr RII low affinity (neutrophils)
Fcr RIII Low affinity (neutrophils)
Major Histocompatibility Complex
(MHC)



MHC is a region of multiple loci that play major
roles in determining whether transplanted tissue
accepted is accepted as self (histocompatible) or
rejected as foreign (histoincompatible)
Is a locus on the short arm of chromosome 6
Classified as
class I MHC genes
class II MHC genes
class III MHC genes






Major Histocompatability complex (MHC):
The MHC complex is a series of genes encoding a
group of highly polymorphic cell membrane
glycoprotien.
In humans these antigens are called human leukocyte
associate antigen (HLA).
HLA are surface antigens present on the surface of
the leucocyte, e.g. macrophages. These play a central
role in immune recognition.
MHC gene complex is located on the short arm of
chromosome 6.
Significance mainly in grafts and organ transplants.
ROLE OF MHC IN ANTIGEN RECOGNITION
T-CELL RECEPTOR(TCR)

Amino acid sequencing of the αβ and γδ heterodimer
revealed a domain structure similar to that of
immunoglobulin.
TCR & ACCESSORY MOLECULES
CD4 & CD8 CORECEPTORS

CD4 is a 55-kDa monomeric membrane glycoprotein
that contains four extra cellular immunoglobulin like
domains, a hydrophobic transmembrane regions and
long cytoplasmic domains containing three serine
residues.

CD8 is a 30-38 kDa monomeric membrane
glycoprotein that contains single extra cellular
immunoglobulin like domains, a hydrophobic
transmembrane regions and long cytoplasmic
domains containing 25-27 serine residues.
SIGNAL TRANSDUCTION
CYTOKINES



Cytokines are small polypeptide with a wide
spectrum of inflammatory, hemopoietic,
metabolic and immunomodulatory properties by
a variety of cells including macrophages,
dentritic cells, lymphocytes, endothelial cells and
fibroblast. (Arai et al 1990)
Cytokines are low molecular weight protein or
glycoprotein secreted by white blood cells or
various cells in the body in response to a
number of stimuli.
Cytokines serve as a messenger of the immune
system.




Cytokines act as an Autocrine hormone,
stimulating the same cell from which it was
secreted.
Cytokines also may stimulate cells in close
proximity to the cells, which secreted them
(Paracrine effect).
These protein hormones may enter the
circulation, where they can interact with immune
cells at some distance from their point of origin
(Endocrine effect)
Intracrine a mechanism involving the direct
action of a cytokine within a cell.
ACTION OF CYTOKINES

Autocrine action

Paracrine action

Endocrine action
CLASSIFICATION
JAN LINDHE
1. Proinflammatory cytokines
E.g. IL-1, IL-6 and TNF
2. Chemotactic cytokines E.g. IL-8
3. Lymphocytes signaling cytokines
E.g. Cytokines released by Th1- IL-2, IFN
Cytokines released by Th2- IL-4,IL-5,IL-10 and IL-13.
NIESENGARD AND NEWMAN
First group: Cytokines, which serve as mediators of
innate immunity.
E.g. Interferon and , TNF and IL-6.
Second group: Cytokines that regulate the growth and
differentiation of lymphocytes.
E.g. IL-2, IL-4 AND TGF-BETA
Third group: These cytokines regulate the hematopoietic
activity in the bone marrow and collectively referred to
as Colony Stimulating Factors or CSF’s produced by
stromal cells or antigen stimulated T- lymphocytes.
E.g. GM-CSF, G-CSF, M-CSF, MULTI- CSF, IL-3,
IL-7. Fourth group: Cytokines which share the
common property of being activators of inflammatory
cell function.
E.g. Interferon 
Basic model for cytokine action
A simple model for cytokine
activation of a cell is shown (The
structures illustrated are based on
those of the IL-6 receptor)
cytokine binds to its receptor on
the cells and induces
dimerization or polymerization
of receptor polypeptides of the
cell surface. This causes
activation of intracellular
signaling pathways (e.g. kinase
cascades) resulting in the
production of active
transcription factors which
migrate to the nucleus and bind
to the enhancer region of gene,
induced by that cytokine.
ROLE OF CYTOKINES IN THE EARLY PHASES
OF AN IMMUNE RESPONSE
Among the cytokines released by
macrophages in response to microbial
components, TNF-  and IL-2 are
particularly important. This early
phase of mediator release has three
fundamental functions:
1. Supply signals to endothelial cells
that initiate recruitment of leukocytes.
2. Activate Phagocytic cells within the
tissues and so provide innate
resistance while the T-cell mediated
response is developing.
3. Provide some of the signals that
determine the type of T-cell response
that will develop.



Role of cytokines in leukocyte
recruitment
TNF-, IL-1 and lipopolysaccharides (LPS) induce
expression of E-selectin and P-selectin on endothelium.
These interact with oligosaccharides or circulating
leukocytes, causing them to slow and roll along the
endothelial surface.
The cytokines also increase expression of ICAM-1.
Chemokines, including MCP-1, RANTES and MIP-1
released from macrophages, tissue cells and endothelium
respectively attach to the endothelium, when they trigger
tethered leukocytes, enhancing the functional affinity of
leukocyte integrins.
The integrins interact with their ligand, ICAM-1 causing firm
adhesion of the leukocytes to the endothelium. Finally, the
cells migrate through the endothelium and can move cup
gradients of chemotactic mediators. The details of the
recruitment and the precise sets of adhesion molecules and
chemokines vary between different leukocyte populations.
Role of cytokines in leukocyte
recruitment
Interleukin-1
Interleukin –1 is a very potent multifunctional cytokine that
appears to be a central regulator of the inflammatory and
immune responses.
The term Interleukin-1 was introduced in 1979.
IL-1 is a Pleotropic cytokine with a variety of activities.
It includes osteoclast activating factor (OAF) because of
stimulation of osteoclasts and lymphocyte activating factor
(LAF) because of its ability to stimulate proliferation of
phytohemagglutination-treated T-cells.
It is secreted by monocytes, macrophages, B-cells, fibroblasts,
neutrophils, and epithelial cells.
Bacterial Lipopolysaccharide is a potent commonly used
stimulus for IL-1 production.






IL-1 synthesis is suppressed by several endogenous factors,
such as Corticosteroids, Prostaglandins, Cytokines like IFN, IL-4.
Some of the other cytokines share biologic activities with IL1, most importantly IL-6 and TNF factor.
There are 2 principal forms of IL-1 that have agonist activity,
IL-1, IL-1, with a third ligand, IL-1 receptor agonist (IL1ra) that functions as a competitive inhibitor.
Two IL-1 receptors are found on the surface of the target
cells, designated IL-1 receptor-1 and IL-1 receptor 2.
IL-1R1 is generally thought to mediate most of the responses
to IL-1.
IL-1R2 has been reported to function principally as a decoy
receptor
Biologic effects of IL-1 include

Lymphocyte activation, macrophage activation,
Natural killer stimulation, Prostaglandin
formation, Fever induction, Anorexia, Acute
phase protein release, Adrenocorticotophin
release, Corticosteroid release, Cytokine gene
expression, Plasminogen activator, Endothelial
cell activation, Tumor cell growth inhibition,
and suppression of lipoprotein lipase gene
expression.
INTERLEUKIN-2 (IL-2 or  or )
.
IL-2 ( and) was originally called T-cell growth factor
because of its effect on mitogen or antigen activating T-cells
and is known to play a general role in immune responses.
IL-2 also stimulates macrophage functional activity,
modulates natural killer function and induces natural killer
proliferation.
It is secreted by Th cells and NK cells.
The molecular wt of IL-2 is approximately 20,000 KD.
Interleukin-2 receptors


Three different forms of the human IL-2
receptors have been identified. These receptors
interact with IL-2 with characteristically
different affinities, specifically high, intermediate
and low affinities.
The high affinity IL-2 receptors comprise at
least two different IL-2 binding subunits termed
IL-2R and IL-2R.
Clinical aspects



Used in Tumors immunotherapy, either using
IL-2 alone or in combination with in-vitro
activated lymphokine-activated killer cells.
The potential for IL-2 as a cancer treatment is
based on activation of cells, which are cytotoxic
to the tumor.
Adverse effects: fever, chills, fatigue, nausea,
vomiting, capillary leakage syndrome or vascular
leakage syndrome, characterized by the
accumulation of edema fluid in pleural cavities.
IL-2
Interleukin-3





IL-3 is a distinct hematopoietic factor affecting multiple
hematopoietic cell lineages.
IL-3 also known as burst-promoting factor, B- cells
stimulating factor, hemopoietic cell growth factor and multi
colony stimulating factor is produced primarily by activated
helper T type I and II cells.
This molecule stimulates the growth of colonies of mast
cells, neutrophils, macrophages, eosinophils, and
megakaryocytes.
It is secreted by activated helper T cells, NK cells.
IL-3 acts as a link between the T- lymphocytes and mast
cells of the immune system, and the hematopoietic system,
which generates the accessory cells granulocytes, phagocytes,
and platelets, which carry out repair and defense responses.
Interleukin-4







IL-4 originally called T-cell-derived B-cell growth factor
(BCGF-1) because of its activation of B cells.
Also called as migration inhibition factor.
It is also play a role in the activation, proliferation and
differentiation of B cells, T-cell growth, macrophage
function, and growth of mast cells.
IgE synthesis by B cells is also induced by IL-4.
It is secreted by helper Tcells.
Mwt 15000 to 20000.
Receptors for this cytokine found on T-cells, B-cells, mast
cells, myeloid cells, fibroblasts, neuroblasts, stromal cells,
endothelial cells and monocytes.
Effects on macrophages


It can activate macrophage cytocidal function
and increase macrophage expression of class II
MHC proteins.
It suppresses the synthesis of proinflammatory
cytokines, such as IL-1, IL-6, IL-8 and TNF- 
and activated monocytes.
Interleukin-5







Interleukin-5 is the name given to a lymphokine (a
cytokine produced by lymphocytes).
Coffman and colleges found that IgA enhancing factor
was IL-5 when the protein is sequenced.
Metcalf used the term eosinophil colony stimulatory
factor to describe this cytokine.
Thus initially known as B- cells growth and
differentiation factor, IgA enhancing factor, eosinophil
colony stimulating factor.
IL-5 is heterogeneous glycoprotein with a molecular
weight of 40000- 50000.
The major function of IL-5 in humans is to stimulate
the production of eosinophils.
IL-5 not only increases the number of eosinophils but
also has been reported to increase their function.
Interleukin-6




Interleukin-6 is a multifunctional cytokine produced by
various cells such as activated monocytes or
macrophages, endothelial cells, activated T-cells, and
fibroblasts.
Formerly these molecules were known as B- cells
stimulatory factor II, interferon B2 and plasmacytoma
growth factor.
Its effect on B cells is to promote growth and facilitate
maturation of the B cells causing immunoglobulin
secretion.
IL-6 increases in sites of gingival inflammation and
plays a role in bone resorption.
SOME OF THE EFFECTS OF
INTERLEUKIN-6 (IL-6)

IL-6 is a typical cytokine, in that it has a
range of effects on many organ systems. In
addition, IL-6 stimulates osteoclast
formation and activity, particularly other
osteogen depletion
Interleukin-7
Secreted by thymus, spleen and bone marrow stromal cells
that functions as a growth factor for T and B cells precursors.
It was formerly known as lymphopoitin 1 based on its
capacity to influence early lymphopoiesis.
IL-7 enhances the function of mature activated lymphocytic
cells, particularly those with cytotoxic activity. At higher
concentrations, IL-7 also increases macrophage cytotoxic
activity and induces cytokine secretion by monocytes.
Interleukin-8






is Chemotactic for neutrophils, increases their
adherence to the endothelium.
In general these cytokines are produced by:
1. Antigen stimulated T lymphocytes
2. Mononuclear phagocytes, endothelial and
epithelial cells, and fibroblasts that have been
activated by other cytokines or LPS.
3. Platelets.
All members of this family stimulate leukocytes
and contribute to inflammatory responses.
Interleukin-9



is a heavily glycosylated polypeptide lymphokine
with an apparent MW of 30000 to 40000.
It is secreted by IL-2 activated T-cells and
Hodgkin's lymphoma cells.
It is a T cell growth factor, which acts in synergy
with other cytokines.
Interleukin-10





IL-10 is an 18000 MW protein that is produced late in the
activation process by Th2 cells, CD8 T cells, monocytes,
keratinocytes and activated B cells.
It was originally called cytokine synthesis inhibitory factor
because of its ability to inhibit cytokine production by
activated T-lymphocytes i.e., Th1 cells and NK cells.
IL-10 inhibits the antigen presenting capacity of
monocytes.
IL-10 also synergies with other cytokines to stimulate
proliferation of B cells and mucosal mast cells.
Together with TGF beta it causes IgA production by B
cells.
Interleukin-11




Biologic activities of IL-11:
Growth promotion of a plasmacytoma cell line:
Originally IL-11 was detected based on its ability to
stimulate the proliferation of an IL-6 dependent mouse
plasmacytoma cell line.
The ability of IL-11 to support the growth of such a
plasmacytoma cell line suggest that cytokine may be
removed in the establishment and maintenance of
plasmacytomas in vivo and may play an important role
in the tumourogenesis.
Biologic activities of IL-11




Growth promotion of a plasmacytoma cell line:
Originally IL-11 was detected based on its ability to
stimulate the proliferation of an IL-6 dependent mouse
plasmacytoma cell line.
The ability of IL-11 to support the growth of such a
plasmacytoma cell line suggest that cytokine may be
removed in the establishment and maintenance of
plasmacytomas in vivo and may play an important role
in the tumourogenesis.
Hematopoietic colony stimulating activity


Alone, IL-11 cannot support the growth of
megakaryocyte colonies but stimulates and
increases in numbers, size of megakaryocyte
colonies in combination with IL3.
Therefore IL-11 is not a megakaryocyte colony
stimulating factor but rather acts like a
megakaryocyte potentiator, their results suggest
that IL-11 may play an important role in
megakaryocytopoiesis and possibly in vitro
platelet production.
Interleukin-12







It was originally called cytotoxic lymphocytes
maturation factor (CLMF) or NK cell stimulatory
factors.
Its molecular wt about 35000 to 40000.
It is produced predominantly on activation by B cells
and macrophages.
It acts synergistically with IL-2 to induce IFN- by Tcells and NK cells
It is a key factor in the development of Th1 cells,
stimulating both their proliferation and differentiation.
It suppresses Th2 dependent functions, such as the
production of IL-4, IL-10, IgE antibodies.
IL-12 also induces the production of GM-CSF, TNF,
IL-16, IL-2.
IL-12
Interleukin-13


The marked structural homology between IL-4
and IL-13 and the close juxtaposition of their
genes on the chromosome suggest that gene
duplication occurred.
IL-13 is predominantly expressed in activated
Th2 cells and regulates human B cell and
monocytic activity.
Interleukin-14






IL-14 is a 50-60 KD glycosylated cytokine otherwise
known as the high mol wt B cell growth factor.
IL-14 is thought to play a role in the development of B
cell memory.
It enhances the proliferation of activated B cells and
inhibits the synthesis of immunoglobulin.
It is produced by follicular dendritic cells and activated
T cells.
IL-14 receptors are found only in cells of the B cells
lineage.
IL-14, participates mainly in secondary humoral
immune responses.
Interleukin-15



IL-15 is widely expressed in kidney, lung, liver,
heart and bone marrow stroma.
It is produced most abundantly by epithelial
cells and monocytes, but not by T lymphocytes.
It functions as a signal from non lymphoid cells
for generating T cell dependent immune
responses.
Interleukin-16


IL-16 which was previously known as
lymphocyte chemoattractant factor (LCF) is
produced by lymphocyte and induces the
directional migration of CD4+ T cells,
eosinophils and monocytes.
The chemoattractant effect of LCF is blocked
by anti CD4 Fab fragments suggesting that CD4
or CD4 related molecules are required for the
effects of LCF on target cells.
interleukin-17
In 2005 Vernal R, Dutzan N et al studied levels of
interleukin-17 in gingival crevicular fluid and in
supernatants of cellular cultures of gingival tissue from
patients with chronic Periodontitis.
They took study group as 16 adult patients [ five
males and 11 females : with age range 35-51 years old,
moderate to advanced periodontitis selected.
GCF sample were assayed by ELISA to determine
the level of IL-17, by R&D Quantikine.
And protein determination by used BIO-RAD
microassy. And results showed IL-17 in GCF was
analyzed in 32 samples from 16 patients with
periodontal disease and in 16 samples from 8 healthy
subjects.
The total amount of cytokine IL-17 was
significantly higher in the periodontitis group
than the control group.
So they conclude that the total amount
of cytokine IL-17 in GCF samples and in the
culture supernatants of gingival cells are
significantly increased in periodontal disease.
JCP: 2005:32:383-389
Interferons
Interferons have been divided into two types: Type I an viral
interferon has been further divided into alpha and beta
subcategories. Type II or immune interferon is referred to as gamma
interferon.
IFN-alpha is leukocyte derived where as IFN-beta is derived from
fibroblasts. IFN-gamma is however derived from stimulated T cells
of both CD4+ and CD8+ lineage.
Both IFN-  and  are characterized by their antiviral activity, IFN
 appears to be more integrated part of the immune system.
IFN  is stimulated by IL-2 has a molecular wt of 35 –70 KD and
in addition to its antiviral activity appears to have an important role
in the stimulation of cytotoxic T cells and NK cells activity.
It also plays an important role in B-cells differentiation and in
production of Igs under some conditions.
INF-γ
TUMOR NECROSIS FACTOR (TNF  and )
Produced by macrophages and TH cells and
causes necrosis of certain tumors and also plays
a role in the activation of osteoclasts and
stimulate them to cause bone resorption. They
may also play a role in vascular changes seen in
periodontal disease.








TNF is a principal mediator in the host inflammatory response.
The main cell type secreting TNF is the mononuclear phagocyte.
The main stimulus for release is the Lipopolysaccharide of
bacterial cell walls.
There are two structurally and functionally similar forms of TNF 
and  but they differ biochemically.
TNF  is 17 KD is derived from stimulated macrophages and
appears to have significant stimulatory activity on the cytoxic T
lymphocytes (CTL) responsible for lysing tumor or virally infected
cells.
TNF- is a 25 KD glycoprotein derived from activated T cells with
a 28% homology to TNF-
 Form is occasionally known as lymphotoxin these virtually have
similar actions, which includes CTL stimulation, osteoclast
activation of PMNLs and antiviral activity.
TNF also appears however to act synergistically with cytokines
and induces release of IL-1.
Chemokines






They generally have low molecular weights, ranging from 7-14
KDa, and stimulate recruitment of leukocytes.
Chemokines are secondary proinflammatory mediators, i.e.,
they are typically induced by primary proinflammatory
mediators such as Interleukin –1 or TNF.
By recruitment of leukocytes, chemokine activity leads to
activation of host defense mechanisms and stimulates the
early events of wound healing.
There are two major chemokine subfamilies based upon the
portion of cystine residues i.e. CXC and CC.
The CXC family members also known as the alpha
Chemokines. They primarily stimulate neutrophils.
C Chemokines are also known as the beta Chemokines. They
stimulate Basophiles, eosinophils, T-lymphocytes and NK
cells.
CYTOKINE RECEPTORS





Immunoglobulin super family receptor
Class I cytokine receptor family
Class II cytokine receptor family
TNF receptor family
Chemokine receptor family
CYTOKINE CROSS REGULATION


INF-γ inhibit TH2 subsets
IL-4 & IL-10 inhibit TH1 subsets
ROLE IN PERIODONTAL
DISEASE


Cytokines play a major role in periodontal
disease. (Alexander 1994)
Cytokine role in
Severe progressing periodontitis
 Chronic, but stable periodontal lesions
Healthy sites


Levels of IL-1, IL-8, and IL-10 and RANTES (Regulated on
activation, Normally T-cell expressed and secreted) in gingival
crevicular fluid and cell populations in adult periodontitis
patients and the effect of periodontal treatment. (Journal of
periodontol 2000,
This study was carried out by J. Gamone et.al., and
they concluded that the amount of crevicular IL-1, IL-8,
IL-10 and RANTES. RANTES is associated with
periodontal status. Removal of the bacterial plaque
reduces the antigenic stimuli and consequently could
modulate the chemokines present in GCF. They
proposed that the dynamic interaction between the
cytokines, their production rate and their quantity could
represent controlling the induction and collapse of the
cytokine network present in the periodontal disease.
Mechanism by which IL-1 could contribute to the net loss of periodontal tissues
IL-1
Stimulate
adhesion
molecule
and chemokine
expression
Inflammation
Stimulate
production of
inflammatory
mediators(PGE2)
Bone loss
Enhance
Osteoclast
formation and
activity
Induce matrix
metalloproteinase
expression
Connective
tissue breakdown
Stimulate apoptosis
of matrix producing
cells
Limit repair
of periodontium











NEUTROPHIL ABNORMALITIES AND
PERIODONTIUM
Disorders of Neutrophil are commonly associated with severe
periodontal destruction.
Neutrophil abnormality could be either qualitative (or)
quantitative
Henceforth the following are to be considered.
i) Neutropenia and agranulocytosis
ii) Leucocyte adhesion deficiency
iii) Hyper Immunoglobulinemia E
iv) Chediak- Higashi syndrome
v) Specific granule deficiency
vi) Papillon- lefevre syndrome
vii) Chronic granulomatous disease
viii)
Down’s syndrome
CONCLUSION
Dental plaque and pure cultures of bacteria
can also activate complement by the alternate
pathway in the absence of an antibody. In
addition to complement chemotactic factors,
certain species of bacteria produce peptides of
low molecular weight that are directly
chemotactic and do not require complements.
This products could contribute to the
accumulation of inflammatory cells in the
periodontal lesions.
REFERENCES


Soluble antagonists to interleukin-1 and TNF
inhibits loss of tissue attachment in experimental
Periodontitis (Journal of clinical periodontology,
2001) .
This study was carried out by Delima A.J.,
Assuma R., Schwartz Z. They concluded that loss of
connective tissue attachment and progression of
periodontal disease can be retarded by antagonists to
specific host mediators such as IL-1 and TNF and
may provide a potential treatment modality to combat
the disease process.

Acute inflammatory phase –
enhanced neutrophil migration into sulcus
Increased flow of serum proteins
Epithelial cell proliferation
Selective local accumulation of mononuclear
cells (kornman et al 1997)




Acute inflammatory gingivitis lesions- Tcells
(Seymour et al 1979)
Chronic inflammatory periodontal lesion –B
cells
(page & schroeder 1976)
Shift in cytokine profile from T helper 1 to
helper 2 responses
(Ishikawa 1997)
Shift has been observed in chronic periodontal
inflammation
( Gemmel & seymour 1994)