T cells, dendritic cells, autoimmunity

and the hair follicle

Daniel H. KaplanDepartments of Dermatology and

ImmunologyUniversity of Pittsburgh

Skin-resident Immune Cells

Langerhans Cells

(LC)

CD103+ dDC CD11b+ dDC

TCR γδ T cell

CD8+ TRM

DETC

ILC

CD4+ TRM

Nerves

Langerhans Cells

(LC)

CD103+ dDC CD11b+ dDC

TCR γδ T cell

CD8+ TRM

DETC

ILC

CD4+ TRM

Nerves

What determines Epidermal

Residence?

Skin-resident Immune Cells

LC and TGFb

TGFb1-/- mice lack LC

TGFb1 likely required by LC precursors

TGFb1 promotes LC differentiation in vitro

TGFb1 is required for LC development

Adult mouse LC require TGFβ for

epidermal residence

Bobr PNAS 2012

Adult human LC require TGFβ for

epidermal residence

HA

LCKC

→control losartan

0

5

10

15

20

25

30

35

Nu

mb

er L

C p

er m

m

****

WT TGFβ1∆LCTGFβRI-CALC

0

0.5

1.0

1.5

Re

lativ

e L

C #

Epi LN

TGFβRI-CALC

0

1

2

3

Re

lativ

e L

C #

Epi LN

TGFβ1∆LC

Isotype control

WT CA-TGFβRILC

Isotype control

CD86

MHCII

CCR7

WT

CA-TGFβRILC

Anti-αvβ6

Anti-αvβ6

→

→

→

Anti-αvβ6

WT

MHCII

Langerin

Overlay

Control

Losartan Example #1

Losartan Example #2

TGFβ1 and TGFβRII Ablation in

Adult LC Promotes LC Migration

Bobr PNAS 2012

huLangerin-CreERT2 x TGFβf/f huLangerin-CreERT2 x TGFβRIIf/f

LC require autocrine/paracrine TGFβ

for epidermal residence

Adapted from Wipff et al. EJCB, 2008.

TGF-β1 Secreted as Latent Complex

In skin epidermis only

αvβ6 and αvβ8 activate

latent TGFβ1 Yang, JBC 2007

Activation of TGFβ by αvβ6 required

for LC epidermal residence

Interfollicular epidermis (IFE)

Isthmus (IM)

Bulge

DAPI Langerin

CD45- Sca1-

Subsets of Keratinocytes

Adapted from Heath, NI 2012

Nagao, NI 2012

αvβ8 and αvβ6 are expressed by

different keratinocytes

LC IFE IM Bulge0.0

0.5

1.0

1.5

2.0 Itgβ6

Ex

pre

ss

ion

/HP

RT

Itgβ8

0

20000

40000

60000

80000

100000

LN

LC

#

**

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

Ep

ide

rma

l LC

%

0

5

10

15

20

25

LC

pe

r fie

ld

IFE HF

***

0.0

0.1

0.2

0.3

0.4

LN

LC

%

***

0

2

4

6

# L

C in

HF

/fie

ld

Itgβ8∆LCWT

Itgβ8∆KCWT Itgβ8∆KCWT

Itgβ8∆KCWT Itgβ8∆KCWT Itgβ8∆KCWT

Itgβ8∆KCWT

IFE IFE

IMIM

A B

C D

E

F G

**

αvβ6 is Required for LC in

Interfollicular Epidermis

αvβ8 is required for LC in

follicular epidermis

LC IFE IM Bulge0.0

0.5

1.0

1.5

2.0 Itgβ6

Ex

pre

ss

ion

/HP

RT

Itgβ8

0

20000

40000

60000

80000

100000

LN

LC

#

**

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

Ep

ide

rma

l L

C%

0

5

10

15

20

25

LC

pe

r fie

ld

IFE HF

***

0.0

0.1

0.2

0.3

0.4

LN

LC

%

***

0

2

4

6

# L

C in

HF

/fie

ld

Itgβ8∆LCWT

Itgβ8∆KCWT Itgβ8∆KCWT

Itgβ8∆KCWT Itgβ8∆KCWT Itgβ8∆KCWT

Itgβ8∆KCWT

IFE IFE

IMIM

A B

C D

E

F G

**

Itgβ6-/-WT Itgβ6-/-xItgβ8∆KC

0

100

200

300

400

LC

pe

r fie

ld

WT Itgβ6-/-xItgβ8∆KCItgβ6-/-

Itgβ6 and Itgβ8 determine LC

patterning through TGFβ activation

Loss of TGFβ signaling is required

for UV-induced LC migration

UV reduced Integrin expression by

KC

KC

KC+U

V

Itgβ6

exp

ressio

n

Itgβ8

exp

ressio

n

KC

KC+U

V0.00

0.25

0.50

0.75

1.00

1.25

0.00

0.05

0.10

0.15

0.20

KC

KC+U

V

0.0

0.5

1.0

1.5

RLU

******

***

Loss of TGFβ signaling is required

for UV-induced LC migration

What about other epidermal cells?

Langerhans Cells

(LC)

CD8+ TRM

DETC

CTCL Psoriais Fixed Drug Vitiligo Alopecia Areata

Trm epidermal residence requires

avβ6 and avβ8

Trm in dermis, LN, spleen unaffected by absence of avβ6

avβ6 blockade depletes epidermal

and SI epithelial Trm

avb6/b8

KC

TGFb

R

TGFb

TGFb-LAP

Trm

TGFb

RTGFb-LAP

LC

Model

Retention of LC and Trm in Epidermis

Epidermal retention

Epidermal retention

TGFb

LC migration

Loss of epidermal maintenance

Migratory signal

avb6/b8

KC

TGFb

R

TGFb

TGFb-LAP

Trm

TGFb

RTGFb-LAP

LC

Model

Retention of LC and Trm in Epidermis

Epidermal retention

Epidermal retention

TGFb

Keratinocytes directly control epithelial retention of

leukocytes via a novel mechanism of intercellular

communication

• LC migration is cell extrinsic (i.e. Keratinocytes

determine LC migration)

• Avβ6 and Avβ8 are spatially distinct and regulated

• DC and T cell retention varies by epidermal anatomy

and could be differently regulated

• Targeting TGFβ or its activation could be used to deplete

TRM from epidermis (e.g. Alopecia Areata, Psoriasis,

CTCL, Vitiligo)

Mohammed et al. Nature Immunology, 2016

Acknowledgements

University of Minnesota

Javed Muhammed

Aleh Bobr

Nathan Welty

Brian Chicione

Sakeen Kashem

Botond Igyarto

Brian Astry

David Masopust

Lalit Beura

NIAMS Dermatology

Foundation

Sloan Kettering Cancer

Ming Li

INSERM, Lyon

Laurent Bartholin

UCSF

Dean Sheppard

NYU

Dan Rifkin

Mayo Clinic

Alina Bridges