1. Role of AIRE in Thymoma-associated
Myasthenia Gravis ?
Alexander Marx, MD
University Medical Centre Mannheim
University of Heidelberg
AIRE-PHD1
Thymoma
AIRE in mTEC
EuroMG
Paris,

2. APECED/APS-1 and AIRE The Autoimmune regulator (AIRE)
is a gene mutated in autoimmune
polyendocrinopathy candidiasis
ectodermal dystrophy or APECED
Thymus
Several autoimmune (endocrine) diseases (highly variable)
Hypoparathyroidism & Addison’s disease
Type 1 diabetes mellitus
Gonadal dysfunction (e.g. premature ovarian failure)
Autoimmune hepatitis, Alocecia, Autoimmune Thyroid Disease...
Mucocutaneous Candidiasis (often first & leading symptom)
Virtually 100% of patients have auto-Ab to type I interferons
EuroMG, Paris

3. Regulation of > 1000 genes
AIRE is mainly expressed in keratin-positive medullary thymic
epithelial cells (mTEC), less commonly in dendritic cells
Aire
Pan-
Cytokeratin (mTEC)
Regulation of > 1000 genes
EuroMG, Paris

4. and some other genes mainly in medully thymic epithelial cells
Aire drives „promiscuous“ expression of „tissue-specific antigens“ (TSA)
and some other genes mainly in medully thymic epithelial cells
Aire
p450_c17
Aire
Thyroglobulin
Pärt Peterson
AIRE-dependent TSA: Insulin, TPO, casein b, a-subunit of AChR, p450, S100 A8
EuroMG, Paris

5. Functional effect of AIRE-driven autoantigen expression
in medullary thymic epithelial cells (mTECs)
Apoptotic mTEC
mTEC DC
Cross-presentation
by dendritic cells (DC)
Promiscuous expression
and improved prentation
of autoantigens & MHCII
Tolerance Induction
Mathis & Bennoit, ARI, 2009
EuroMG, Paris

6. Significant Correlation between Prevalence of HCs and Prevalenve
of AIRE+ Cells in Normal Human Thymus
r = 0.81
p<
EuroMG, Paris

7. Age-dependent decline of Hassall‘s Corpuscles and
AIRE+ cells in normal human thymus
HCs
Aire+ Cells
Aire/HCs ~ (0 - 40y)
~ (41- 90y)
Hassall‘s Corpuscles & Aire+ Cells per Area
Mean HCs per area NT
Outlier (HCs)
Mean Aire+ per area NT
Outlier (Aire+)
Age, Decades
EuroMG, Paris

8. Among WHO-defined Thymomas Hassall‘s Corpuscles are common
only in Type B1 Thymomas („predominantly cortical“)
WHO-Classification: 1999, 2004 A AB B1 B2 B3
„C“
„Medullary“
Mixed
„Cortical“
TSCC
Histogenetic Classification: Marino & Müller-Hermelink, 1985; Kirchner, 1992
EuroMG, Paris

9. AIRE--- >95% of thymomas, including all type A & AB
thymomas do not express AIRE* (Ströbel, 2007)
Thymus Type B1§
§ ~50% of type B1 thymomas are Aire+
AIRE---
*AIRE, Autoimmune Regulator

10. Loss of AIRE and AIRE-related self-antigen expression
in >95 of thymomas
Ströbel et al. J Pathol 2007

11. Does AIRE-deficiency in thymomas elicit autoimmune
diseases, including APECED ?
Apoptotic mTEC
mTEC NO DC
Cross-presentation
by dendritic cells (DC) NO
Promiscuous expression
and improved presentation
of autoantigens & MHCII
Impaired
Clonal Deletion
Autoimmunity
Mathis & Bennoit, ARI, 2009
EuroMG, Paris

12. MG overlap: anti-IFN type I
Minimal overlap of clinical and serological autoimmune features in APS-1 patients and patients with AIRE(-) thymomas
anti-insulin
anti-GAD65
anti-Cyp1a2
anti-Cyp17
anti-Cyp21
overlap:
anti-IFN
type I MG
ANA
anti-AChR
anti-striational
anti-TPO
EuroMG, Paris

13. Generation and export of CD4+ T-Cells is the „sine qua non“ of
MG development in type AB and B Thymomas (Ströbel; Buckley)
MG+ Thymoma
(Aire ----)
MG-negative
Thymoma (AIRE----)
NT / Thymitis
CD4 RA
CD4 RA
CD4 RA
16,0 %
26,7 %
2,5 %
CD45 RA FITC
CD 4 QR
18,3 %
CD8 RA
25,3 %
4,5 %
CD45 RA FITC
CD 8 PE

14. Production of Regulatory T-cells is Impaired
in Type Ab and B Thymomas (Ströbel, Ann Neurol, 2004)
EuroMG, Paris

15. Thymomas as an human model to study the relationship between
AIRE expression and generation of FOXP3+ regulatory T cells
Ströbel et al. Ann N Y Acad Sci, 2008
Expression /
b-Actin 2 4
FOXP3 NT
MG(+) MG(-) - *
EuroMG, Paris

16. AIRE Expression and Hassall‘s Corpuscles are correlated in B1 Thymoma
Hassall+ B1 Thymoma
AIRE & HC Status of Medullary Islands in B1 Thymomas
Hassall--- B1 Thymoma
AIRE+
AIRE-
Hassall +
343
222
Hassall --- 34
123
P<0.0001
EuroMG, Paris

17. In B1 Thymomas the number of FoxP3+ cells (likely Tregs)
is NOT correlated with the presence of Aire+ cells
FoxP3 per Aire+ cell
FoxP3 per Aire-- cell
Case #
AIRE is probably NOT involved in the generation of Tregs in humans
EuroMG, Paris

18. Why is AIRE Expression Reduced in Thymomas?
EuroMG, Paris

19. NO ! Factors known to be associated with thymic Aire deficiency
in thymic epithelial cells (TECs)
Germ line mutation of Aire gene (APS I, APECED)
Abnormal hyper-methylation of Aire promoter
Lack of LTb, RANK/RANKL, TRAF, RelB / NFkB signalling
Defective T-cell maturation in various SCIDs, Omen Syndrome,
chronic cyclosporine treatment (> secondary defects of TECs)
Defective TEC maturation in thymoma ?
NO !
EuroMG, Paris

20. Phenotypic Markers of Thymic Epithelial Cell Subsets
MHC-IIlo
DEC205+
MHC-IIhi
DEC205+
MHC-IIlo
Aire -----
MHC-IIhi
Aire +/-
Kyewski, 2007
Anderson, 2009

21. „Compartment-specific“ gene expression profiling of thymomas
compared to purified cortical and medullary normal TECs
4606 Genes
on OncoChip
153 53
Gotter et al.
2004
162
443
Cortical Genes
Medullary Genes

22. Hypothetical „Developmental Concept“ of the WHO Thymoma Classification
Mutation
Other MG+Thymoma Types
B1 Thymoma
B1 Thymoma
Oversize of
Cortex
MHC-IIlo
Aire ----
MHC-IIhi
Aire +
EuroMG, Paris

23. Summary AIRE deficiency in thymomas does not correlate with
the MG Status of thymoma patients
the efficiency of intrathymomatous CD4+ thymopoiesis
the capacity to generate FoxP3+ Tregs
AIRE deficiency in thymomas is an indicator of TEC immaturity
and likely of functional insufficiency of TECs in A, AB, B2
and B3 thymomas
The massively increased cortex/medulla ratio in B1 thymomas might
be a structural basis for tolerance failure in AIRE+ B1 thymomas

24. Acknowledgments Mannheim: Philipp Ströbel Wen-Yu Chuang
Christian Sauer
Djeda Belharazem
Li Li
Norbert Gretz
Alexander Marx
Würzburg etc.
Bei Huang
Andreas Zettl
Andreas Rosenwald