XXIV World Allergy Congress 14-17 October, 2015, Seoul Korea

Function and Dysfunction of Skin Barrier

Masayuki Amagai, M.D., Ph.D. Department of Dermatology, Keio University School of Medicine Laboratory for Skin Homeostasis, RCAI, RIKEN Center for Integrative Medical Sciences

Plenary Session 3 Atopic Dermatitis : From Barrier to Inflammation

Allergic rhinitis

Asthma

Food allergy

Allergic disorders in different organs

Allergic disorders

Cutaneous sensitization

Stratum Corenum Atopic dermatitis

Cutaneous sensitization is the initial key step for many allergic disorders

Skin

external antigens

Anaphylaxis

SG2SG3

SG1

Stratum Basale

Stratum Spinosum

Stratum Granulosum

Proliferation

Differentiation

Cell Death

Stratum Corneum

Air-Liquid Barrier

Tight Junction Liquid-Liquid Barrier Langerhans Cell Network

Immune Barrier

Reviewed by Kubo, Nagao and Amagai, J Clin Invest 2012

Epidermal Structure of Mammals

Kubo et al, JEM 2009

Resting Langerhans cells stay under the TJ barrier

Kubo et al, JEM 2009

Activated Langerhans cells elongate their dendrites through TJ barrierTJ-penetrated Langerhans cells sample antigens from their dendrite tips

SC

TJ

Antigen uptake from outside of TJ barrier

Sulfo-NHS-LC-biotin (a TJ impermeable reagent) was topically applied

biotinylated proteins MHC class II

Staphylococcal Scalded Skin Syndrome （SSSS）

Exfoliative toxin (ET, 26-32 kDa) produced by S. aureus cleaves Dsg1 with resultant blister formation.

Amagai et al, Nat Med 2000

Dsg1

Dsg3

ETAPBS

Cutaneous immunization (topical application with patch) leads to ETA-specific IgG1 response and prevents SSSS

WT Langerin-DTR + DT i.p.

WT ETA i.p.

ETA patch-immunize

O.D

. 0.0

0.5

1.0

1.5

2.0

WT

PBS patch-immunize

P<0.005

ETA i.p. challenge

PBS patch-immunize

ETA patch-immunize

DT-treated LDTR ETA

patch-immunize

Ouchi, Nagao et al, JEM 2011

occludin (TJs)

langerin

langerin HLA-DR occludin

3D Visualization of TJs and LCs in normal human epidermis

HLA-DR (Resting LCs)

20 µm

resting LC

Yoshida et al, JACI 2014

Activated LCs penetrated TJ barrier to send their dendrites to the extra-TJ environment in human epidermis.

Langerin accumulated at the tip of TJ-penetrated dendrites

10 µm

TJ barrierSC

activated LC Yoshida, Kubo et al, unpublished

Two sets of Intra-epidermal dendritic cells in AD

1. Langerhans cells (LCs)

Langerin (+) / Birbeck granules (+) HLA-DR (+) High affinity IgE receptor (Fc-epsilon receptor I) (+) Th2 response induction in vitro

2. Inflammatory dendritic epidermal cells (IDECs)

Langerin (-) / Birbeck granules (-) HLA-DR (+) High affinity IgE receptor (Fc-epsilon receptor I) (+) Th1 response induction in vitro

(Wollenberg et al, 1996, 2001; Novak et al, 2004, 2005)

langerin

Yoshida et al, JACI 2014

Langerhans cells (LC) extend their dendrites above tight junction and capture external antigens which penetrate through straturm corneum

Beautiful collaboration by Tight Junction and Langerhans cells to capture external antigens without breaking barrier function

secondary ionsBi+3

Kubo et al, Sci. Rep. 2013

Visualize the unknown structure of the SC by

Time-of-Flight Secondary Ion Mass Spectrometry (TOF-SIMS)

Visualize the distribution of each secondary ion.

TOF-SIMS analyses of corneal layers revealed the three distinct layers in stratum corneum in mice and human

K Arginine

WT

K Arginine

Filaggrin KO

Khigh Argininelow

Klow Argininehigh

Klow Argininelow

K Arginine

Soak in water WT

Arginine of the middle-SC disappeared in filaggrin KO

Upper SC layer functions like a sponge Middle SC layer functions for hydration

Kubo et al, Sci Rep 2013

SC

TOF-SIMS analyses of corneal layers revealed the three distinct layers in stratum corneum in mice and human

K Arginine

WT

Khigh Argininelow

Klow Argininehigh

Klow Argininelow

Cr(III) Arginine

WT

Cr(III) Arginine

Filaggrin KO

Soak in Cr(III)Cl3

Lower SC layer functions as a barrier

Kubo et al, Sci Rep 2013

SC

MHC IILangerin

MHC II+ Langerin- EpCAM-

MHC II+ Langerin+ EpCAM+

Langerhans cell repopulation in the epidermis

Nagao et al, Nat Immunol 2012

Tape strip induces rapid infiltration of leukocytes to hair follicles　（0.5~4.5 hrs)

GFP+ cells were mostly MHC II+ and/or CD11b+

(not shown)

Nagao et al, Nat Immunol 2012

Upregulation of CCL8 expression after tape-stripping

No tape strip 18 hrs after tape stripCCL8

Nagao et al, Nat Immunol 2012

CCL20

CCL2

CCL8

pre-LC (CCR6)

LC/pre-LC (CCR2)

LC (CCR8)

Interfollicular epidermisInfundibulumIsthmusBasal bulgeSuprabasal bulge

CCL1

Mechanical stress

Perturbation-induced chemokine production

HFs are immunologically functional structures that differentially regulate LC/pre-LC recruitment

Stress-induced chemokine production

Nagao et al., Nat Immunol 2012