APECED: monogenic autoimmune disease

Pärt Peterson

University of Tampere, FinlandUniversity of Tartu, Estonia

APS1 or APECED

• APS1 (autoimmune polyendocrine syndrome type 1) or APECED (autoimmune polyendocrinopathy candidiasis ectodermal dystrophy)

• Autosomal recessive inheritance• More prevalent in some populations such as Finns (1:25000), Iranian Jews (1:9000) and Sardinians (1:14400). Very high incidence (1/4400) reported in a small town Bassa del Grappa, in Northern Italy• No HLA association

Autoimmune regulator (AIRE) is a gene mutated in APECED

Clinical Features

• Endocrinopathies– Hypoparathyreoidism– Addison’s disease– Gonadal dysfunction– Type 1 diabetes mellitus– Autoimmune thyroiditis– Autoimmune gastritis

• Chronic mucocutaneous candidiasis

• Ectodermal dystrophies– dental enamel– nails– alopecia– vitiligo

• Autoimmune hepatitis• Keratopathy

Candida infection and vitiligo of APS1 patient

From Prof. Olle Kämpe, Uppsala University

Disease components APS1 APS2

Addison’s disease 60-100 70-100

Hypoparathyroidism 77-100 absent

Chronic candidiasis 73-100 absent

Ectodermal dysplasia 10-77 absent

Autoimmune thyroid disease

8-18 69-83

Type 1 diabetes 4-23 28-52

Hypogonadism 31-60 9

Alopecia 27-72 2-5

Vitiligo 4-26 4-11

Keratopathy 12-35 absent

Autoimmune hepatitis 10-19 4

Pernicious anemia 12-15 2-25

Chronic gastritis 6 11

APS1/APECED and APS2are two different syndromes

Autoantigens in Addison’sdisease

• Steroid 17a-hydroxylase, P450c17

• Steroid 21-hydroxylase, P450c21

• Side-chain cleavage enzyme, P450scc

All three P450 enzymes are active in steroidogenesis in adrenal cortex. P450c21 is expressed only in adrenal cortex, P450c17 and P450scc are also expressed in gonads

Thomas Addison

Krohn et al. Lancet 339: 770, 1992Uibo et al. JCEM 78: 323, 1994

Autoantigen Prevalence %Steroid 21 hydroxylase (P450c21) 66

Side-chain cleavage enzyme (P450scc) 52

Steroid 17 alpha hydroxylase (P450c17) 44

Aromatic L-amino acid decarboxylase (AADC) 51

Glutamic acid decarboxylase (GAD65) 37

Histidine decarboxylase (HDC) 37

Cysteine sulfinic acid decarboxylase (CSAD) 3.6

Tryptophan hydroxylase (TPH) 45

Tyrosine hydroxylase (TH) 44

Thyroglobulin (TG) 36

Thyroid peroxidase (TPO) 36

Transcription factor SOX10 22

Cytochrome P4501A2 (P4501A2) 8

Tyrosine phosphatase-like protein IA-2 (IA-2) 7

APS1/APECED autoantigens

AIRE protein

•N-terminal HSR domain: homodimerisation

•SAND domain: putative DNA binding

•PHD finger: transcriptional regulation

•Proline rich region

•LXXLL motif: binding to nuclear receptors

Nagamine et al. Nat Genetics 17: 393, 1997The Finnish-German Consortium. Nat Genetics 17: 399, 1997

Similarity to Nuclear Proteins

Mi-2: helicase, involved in chromatin remodelling, autoantigen in dermatomyositis

TIF1: transcriptional coactivator

Sp100: interferon responsive, transcription activator, autoantigen in PBC, lymphoid restricted

Sp140: homologous protein to Sp100, autoantigen in PBC

Expression in the Thymus•The major AIRE expressing tissue is the thymus•Lower levels of expression are seen in the fetal liver, spleen and lymph nodes•In the thymus, AIRE is seen in a distinct subset of cells

in situ hybridisation Anti-AIRE ab

Heino et al. BBRC 257: 821, 1999

Aire localizes to nuclear dots in thymus medulla and in transfected Cos cells

Subcellular localization

Human and Mouse AIRE proteins are 77% identicalaa

(23.5%)

PHD PHD

552

430

352

342

301

434

475

PRR

aa

Aire

520

5248 12 64 68

LL L NLSHSR/ASS

99 188

279

PHD PHD

545

430

350

340

299

434

475

PRR

AIRE

516

5207 11 63 67

LL L NLSHSR/ASS

100

189

280

SAND

SAND

L

L(16%)

mouse : MAGGDGMLRRLLRLHRTEIAVAIDSAFPLLHALADHDVVPEDKFQETLRLKEKEGCPQAFHALLSWLLTRDSGAILDFWRILFKDYNLERYSRLHSILDGFPKDVDLNQSR : 111human : MA-TDAALRRLLRLHRTEIAVAVDSAFPLLHALADHDVVPEDKFQETLHLKEKEGCPQAFHALLSWLLTQDSTAILDFWRVLFKDYNLERYGRLQPILDSFPKDVDLSQPR : 110 mouse : KGRKPLAGPKAAVLPPRPPTKRKALEEPRATPPATLASKSVSSPGSHLKTKPPKKPDGNLESQHLPLGNGIQTMAASVQRAVTVASGDVPGTRGAVEGILIQQVFESGRSK : 222human : KGRKPPAVPKALVPPPRLPTKRKASEEARAAAPAALTPRGTASPGSQLKAKPPKKPESSAEQQRLPLGNGIQTMSASVQRAVAMSSGDVPGARGAVEGILIQQVFESGGSK : 221 mouse : KCIQVGGEFYTPNKFEDPSGNLKNKARSGSSLKPVVRAKGAQVTIPGRDEQKVGQQCGVPPLPSLPSEPQVNQKNEDECAVCHDGGELICCDGCPRAFHLACLSPPLQEIP : 333human : KCIQVGGEFYTPSKFED-SGSGKNKARSSSGPKPLVRAKGAQGAAPGGGEARLGQQGSVPAPLALPSDPQLHQKNEDECAVCRDGGELICCDGCPRAFHLACLSPPLREIP : 331 mouse : SGLWRCSCCLQGRVQQNLSQPEVSRPPELPAETPILVGLRSASEKTRGPSRELKASSDAAVTYVNLLAPHPAAPL--LEPSALCPLLSAGNEGRPGPAPSARCSVCGDGTE : 442human : SGTWRCSSCLQATVQEVQPRAEEPRPQEPPVETPLPPGLRSAGEEVRGPPGEPLAGMDTTLVYKHLPAPPSAAPLPGLDSSALHPLLCVGPEGQQNLAPGARCGVCGDGTD : 442 mouse : VLRCAHCAAAFHWRCHFPTAAARPGTNLRCKSCSADSTPTPGTPGEAVPTSGPRPAPGLAKVGDDSASHDPVLHRDDLESLLNEHSFDGILQWAIQSMSRPLAETPPFSS : 552human : VLRCTHCAAAFHWRCHFPAGTSRPGTGLRCRSCSGDVTPAP-VEGVLAPSP-ARLAPGPAK--DDTASHEPALHRDDLESLLSEHTFDGILQWAIQSMARPAA---PFPS : 545

PHD

PHD

L

L

L ASS

SAND

NLS

L

Mittaz et al. BBRC, 255: 483, 1999

MTS5 MTS10

Aire co-localizes with epithelial cell markers in thymus medulla

AIRE is expressed in Dendritic cellsT

hy

CD

8+ D

C

Th

y C

D8lo

/-D

C

Sp

l C

D4+

8- DC

Sp

l C

D4- 8

- DC

Sp

l C

D4-

8+D

C

Th

ymo

cyte

s

Sp

l m

acro

ph

.

Aire

-actin

Several subclasses of mouse dendritic cells express Aire

AIRE mRNA is upregulated in vitro stimulated human DCs

Cortex

Medulla

Double negativeCD4- CD8-No T-cell receptor

Double positiveCD4+ CD8+T-cell receptor

Single positiveCD4+ CD8-

orCD4- CD8+

T-cell receptor

Thymocyte differentiation

TCR reactive to non-self antigens

TCR reactive to self antigens

T-cell precursor

Cell death

Cells survive and when meeting pathogen will proliferate

Thymocytes are selected differentially according to their reactivity

Autoimmune diseases and autoantigens

Addison’s disease steroid P450 cytochromesAutoimmune gastritis H+/K+ ATPasePernicious anemia intrinsic factorHashimoto thyroiditis thyroid peroxidase, thyroglobulinGraves disease thyroid receptorMyasthenia gravis Acetylcholine receptorType 1 diabetes insulin, GAD65Vitiligo tyrosinase, MARTRheumatoid arthritis type 2 collagenMultiple sclerosis myelin basic protein

Many tissue specific autoantigens are expressed in thymus.

During negative selection, T-cells to these antigens are deleted.

If antigen is not expressed in thymus or is expressed in a different way, this may cause autoimmunity

Ectopic (promiscuous) expression of self antigens in thymus

From Gotter et al. 2004

Tissues specific antigens (pancreas, stomach, brain, eye, liver, muscle, kidney specific genes)

Expression of genes expressed during fetal stages, pregnancy-associated genes

Expression of male specific genes in females and vice versa

Expression of cancer specific antigens

Conserved in mice and humans

Estimation of 3000 genes (5-10% of known genes) in addition to basal expression of thymic epithelial cells

Diverse genes expressed in thymic epithelial cells

AIRE (autoimmune regulator) gene is central in expressing tissue specific antigens

Aire deficient mice have autoantibodies and lymphocytic infiltration in multiple tissues

Anderson et al. Science, 2002

Anderson et al. Science, 2002

The expression of tissue specific genes is lower ornon-existing in Aire deficient mouse

Microarray analysis of geneexpression in wild-type and Aire deficient mouse

The PHD zinc fingers form the activation domain of AIRE

HSR SAND PHD PHDPRRNLS

AIRE Interacts with CBP •AIRE binds CBP at its CH1 and CH3 domains by far western and yeast two-hybrid assays•CH1 also binds STAT2 and HIF-1a; CH3 binds E1A and TFIIB

From Hottiger and Nabel, 2000

CBP/p300 interacts with many transcription activators and coactivators

CBP: cAMP response element binding (CREB) protein binding protein

CBP is implicated in various transcriptional responses regulating growth, differen-tiation or apoptosis

Belongs to the class of transcription co-activators possessing histone acetyl-transferase activity (HAT) and thus have the potential to regulate the chromatin structure

AIRE Colocalises with CBP

AIRE mergeCBP

Nuclear Bodies

• Most prominent nuclear bodies are promyelocytic leukemia (PML) nuclear body or POD (PML oncogenic domain)

• Approximately 0.3 to 1 micrometers in diameter• Other proteins in nuclear dots are involved in transcription or

suspected in chromatin binding (Sp100, CBP, BLM, p53)• Function unknown, activation or degradation site?• Some of the proteins like CBP move in and out.

3D picture of AIRE dots

AIRE

T cell autoreactive to APECEDautoantigen

AIRE Function AIRE induces the expression of autoantigens that lead to the elimination of the autoreactive T cells

Thymic epithelial cell expressing autoantigens

Thymus

No AIRE

T cell autoreactive to APECEDautoantigen

Loss of Function When AIRE is defective, autoreactive T cells escape selection, and autoimmunity develops

Thymic epithelial cell expressing autoantigens

Thymus

University of Tampere Jukka PitkänenCamelia MagureanuUlla AapolaNiko SillanpääAstrid MurumägiMaarit Heino Pärt Peterson

Kai Krohn

Keio University, TokyoJun KudohNobuyoshi Shimizu

WEHI, MelbourneHamish ScottLi Wu

University of Geneva Laureane MittazStylianos Antonarakis

University of TokushimaMitsuru Matsumoto

University of WürzburgPhilipp StröbelAlex Marx

University of BirminghamGraham AndersonEric Jenkinson

University of TartuAna RebaneVivian KontKaidi MöllTõnis OrgIngrid LiivEneli ÕisAnnika ReimetsRainis VentaMario Saare