T helper-17 cells

Jafar Ali

M.Phil 2nd

QUAID-i-AZAM UNIVERSITY ISLAMABAD

Th 17 cells

T helper 17 cells (Th17) are a subset of T helper cells producing interleukin 17 (IL-17)

discovered in 2007. distinct from Th1 and Th2 cells defence play a role in inflammation and tissue injury autoimmune disease such as multiple sclerosis Rheumatoid arthritis

Subset of t cells

Th17 cell lineage development

.

RORγT

STAT-3

Naive CD4

APC

Th17 IL-17IL-22IL-21

IL23-APC

IL-6TGF-β

Pre-Th17

Th17 Differentiation

Steps in the generation of Th17 cells.

The activation of naive T cells in the presence of TGF-β and IL-6 initiates the Th17 differen The activation of naive T cells in the presence of TGF-β and IL-6 initiates the Th17 differentiation pathway. Th17 cells produce IL-21, which further amplifies Th17 generation in an autocrine manner. IL-21 also induces the IL-23R on differentiated Th17 cells to make them responsive to IL-23 signaling. IL-23 stabilizes the Th17 phenotype by secreting IL-17A, IL-17F and IL-22 and helping Th17 cells to acquire effector functions. h further amplifies Th17 generati

(Awasthi and Kuchroo, International Immunology, 2009)

Transcriptional regulation RORᴽt……….. necessary and sufficient to induce IL-17

expression ROR∞….. With RORᴽt promotes differntiation of Th 17

cells Runx1, to Il17 promoter and RORᴽt will give optimal IL-

17expression in CD4+ Interleukin regulatory factor 4 (IRF4)….. TH17 induction STAT3………… TH17 cell development and function

is also critically dependent

Disturbances in the homeostasis of Th17 lymphocytes in patients with hyper IgE syndrome (HIES) and chronic granulomatous disease (CGD)

Horvath R.1, Lastovicka J.1, Polouckova A.1, Sedlacek P.2, Bartunkova J.1, Sediva A.1, Spisek R.1

1Department of Immunology, Charles University, 2nd Medical School and Faculty Hospital Motol,

Prague, Czech Republic

Th 17 cell functions

Production of IL-17 cytokines family (IL-17, IL-21, IL-22) which leads to

the chemoattraction of neutrophils

Accumulating Th17 are highly pro - inflammatory and that Th17 cells

with specificity for self-antigens lead to severe autoimmunity- (psoriasis,

Crohn´s disease, multiple sclerosis)

Initially, from studies in mice, Th17 cells were thought to play an important

role in host defense against extracellular pathogens, which are not

efficiently cleared by Th1-type and Th2- type immunity

However, identity of pathogens cleared by Th17 was unknown

Direct evidence for understanding physiological target of Th17 cells came

from studies of patients with mutations in STAT-3, a critical transcription

factor for the differentiation of Th17 cells

Physiological role of Th17 cells in humans

Defective Th17 cells in Hyper IgE syndrome

Primary immunodeficiency caused by mutations in STAT-3 transcription factor, NEJM 2007

Dermatitis, boils, cyst-forming pneumonias, retained primary dentition, bone abnormalities and elevated serum IgE levels

Abnormal and devastating susceptibility to a narrow spectrum of infections, most commonly Staphylococcus aureus and Candida albicans

Abrogated numbers of Th17 cells, Nature 2008, JEM 2008

nonspecific stimulation

Studies in Hyper IgE point to a critical role of Th17 cells in the response

against candidal and staphylococcal infections

However, there are other diseases with similar spectrum of dominant

pathogens where the characteristics of Th17 have not been tested

We thus decided to test Th17 cells compartment in chronic granulomatous

disease

Defective Th17 cells in Hyper IgE syndrome

Clinical mimicry of HIES with other primary immunodeficiencies – Chronic granulomatous disease (CGD)

Primary immunodeficiency

Mutations in the NADPH oxidase system

Profound defect of respiratory burst in myeloid cells

Recurrent infections, organ granulomas

Dominant susceptibility to staphylococcal and candidal infections

Aim of the study

Analyze and compare the characteristics of Th17 compartment in

HIES and CGD patients

Patients and methods

4 patients from 3 families with HIES 7 patients with CGD (2 patients underwent allo-BMT) Mutations in STAT-3 and NADPH oxidase - genetics ELISA

0 102 103 104 105

0

102

103

104

105 4.12

0.51

0 102 103 104 105

0

102

103

104

105

0.13

1.67

0 102 103 104 105

0

102

103

104

105 2.32

1.98

0 102 103 104 105

0

102

103

104

105 5.91

0.49

0 102 103 104 105

0

102

103

104

105

0.078

3.5

0 102 103 104 105

0

102

103

104

105 1.25

2.87

0 102 103 104 105

0

102

103

104

105 6.51

0.76

0 102 103 104 105

0

102

103

104

105 6.97

0.36

0 102 103 104 105

0

102

103

104

105 1.91

1.55

0

0,5

1

1,5

2

2,5

3

3,5

Controls HIES CGD

% o

f IL

-17

+ C

D4

+ c

ell

s0

2

4

6

8

10

12

14

Controls HIES CGD%

of

IFN

ga

mm

a+

CD

4+

ce

lls

IFN

gam

ma

- P

E

IL-17 A647

Controls HIES CGD

AB

Results – Th17 numbers in CGD and HIES

p<0,05

p<0,05

p<0,05

p=0,39

p<0,05

p=0,05

• absent Th17 cells in HIES

• high frequencies of Th17 in CGD

Results – cytokine production

IL-17

0

200

400

600

800

1000

1200

pg/

ml

Controls HIES CGD

A IL-21

0

500

1000

1500

2000

2500

pg/

ml

Controls HIES CGD

p<0,05

p<0,05

p<0,05

p=0,06

p=0,29

p=0,14

IL-23

0

200

400

600

800

1000

1200

pg/

ml

Controls HIES CGD

p<0,05

p<0,05

p<0,05

• low levels of IL-17 and IL-21 in HIES

B

• high levels of IL-17 and IL-21 in CGD

• extremely elevated levels of IL-23 in HIES

• elevated levels of IL-23 in CGD

Th17 effector cytokines Polarization cytokine

0 102 103 104 105

0

102

103

104

105

0.84

8.64

0 102 103 104 105

0

102

103

104

105

0.12

1.83

IFN

gam

ma

- P

E

IL-17 A647

A

Correction of defect in Th17 cells in two CGD patients after successful BMT

0

,5

1

1,5

2

2,5

3

% o

f C

D4

po

s.

T c

ell

s

Th17

CGD

HIES

Controls

0

2

4

6

8

10

12

14

% o

f C

D4

po

s.

T c

ell

sIFN-g

Bp#1

p#2pre-BMT

pre-BMT

CGD after BMT

• normalized numbers of Th17 cells after BMT

p=0,52

p=0,24

post-BMT

post-BMT

Results – cytokine production after allo-BMT

CGD

HIES

Controls

0

200

400

600

800

1000

1200

1400

pg/

ml

IL-17

0

250

500

750

1000

1250

1500

1750

2000

pg/

ml

IL-21

p=0,24

0

200

400

600

800

1000

pg/

ml

IL-23

A Th17 effector cytokines Polarization cytokineB

pre-BMT

pre-BMT

pre-BMT

CGD after BMT

p=0,33

p=0,12

• decreased production of IL17,21 and 23 after BMT

post-BMT

post-BMT

post-BMT

Possible theoretical explanations

Healthy Th17APC

IL-23 IL-17,22,21 etcNeutro

Lympho

Mono

Eradication

CandidaS.aureus

HIES Th17APC

IL-23 IL-17,22,21 etcCandidaS.aureus

STAT3 mutation

In-efficient immune cells attraction

Pathogen persistence

CGD Th17APC

IL-23 IL-17,22,21 etc

Neutro

Lympho

Mono

In-efficient eradication

CandidaS.aureus NADPH mutation

Pathogen persistence

Conclusions

We identified disturbances in the homeostasis of Th17 lymphocytes

in HIES and CGD patients

Absent Th17 cells in STAT-3 deficient HIES patients

Significantly higher frequencies of Th17 cells in CGD

Increase of Th17 cells in CGD is likely to be secondary as a result

of defect in neutrophils

BMT leads to the normalization of elevated Th17 cell numbers and

coresponding IL-17 production

Positive pro-inflammatory loop caused by Th17 cells contributes to

the formation of granulomas

These findings confirm the critical role of Th17 lymphocytes in the

elimination of candidal and staphylococcal infections