IPEX background

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ESID Prague Spring Meeting May 14 and 15,
2007 Prague
A FAMILY AFFECTED BY ATYPICAL IPEX SYNDROME
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Immunedysregulation Polyendocrinopathy
Enteropathy X-linked IPEX
A rare genetic disorder of immune regulation
characterized by overwhelming systemic
autoimmunity
It is caused by mutations in the FOXP3 gene ,
located on X-chromosome, key molecular factor
driving T cell tolerance and crucially important
for CD4CD25 regulatory T cell development and
function
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What does FOXP3 do?
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FOXP3

• Plays an essential role in the development
• and function of CD4CD25 Regulatory
• T cells
• Hori S, et al., Science 2003
• Khattri R, et al., Nat. Immunol. 2003
• Fontenot JD, et al., Nat. Immunol. 2003
• FOXP3 may function as a transcriptional
• repressor of cytokine promoters
• Schubert L, et al., J. Biol. Chem. 2001
• Rheostat of the immune response
• Khattri R, et al., J. Immunol. 2001

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FOXP3
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CD4CD25 Regulatory T Cells
REGULATORY T CELLS
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• Make up 5-10 of the normal CD4 T cell
  population.
• Characterized by expression of CD4 and CD25bright
  at baseline and of intracytoplasmatic expression
  of FOXP3. They are positive for Cytotoxic T
  Lymphocyte associated Antigen-4 (CTLA-4) e
  Glucocorticoid-Induced Tumor-necrosis factor
  receptor-Related protein (GITR) recently, it has
  been reported that they have low expression of
  CD127.
• Require activation and cell contact to repress
  proliferation of other T cells but do not appear
  to proliferate themselves after activation.

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CLINICAL LABORATORY FEATURES
BASIC Clinical Laboratory Features
Other Clinical Laboratory Features
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Locations of FOXP3 mutations reported
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From Ochs HD et al. Immunol Rev. 2005
Feb203156-64. Review.
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MILD PHENOTYPES
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CLINICAL CASE
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Male born to healthy unrelated parents after 37
wks of pregnancy, complicated with diabetes and
IUGR.
At birth, weight was 2580g. The neonatal period
was unremarkable.
At age of 1 month he was admitted to our hospital
for vomiting and severe bloody diarrhea
Lab evaluation resulted negative for common GI
infections, total protein were low (3.6 g/dl) and
anemia was present (Hb 10g/dl)
Severe and intractable diarrhea persisted and
because of his progressive clinical deterioration
total parenteral nutrition as well as treatments
of support were started.
Intestinal biopsies showed histological findings
compatible with autoimmune enteropathy
Clinical improvement was slowly obtained when
immunosuppressive therapy was started (high-dose
intravenous corticosteroids combined to oral
cyclosporin)
Although absence of any endocrine dysfunction and
skin lesions, due to life threatening
enteropathy, a diagnostic procedure for IPEX
syndrome was considered.
Unfortunately the patient died prematurely at age
of 5 month while he was on immunosuppression
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Molecular analysis of FOXP3
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Wild Type
543 CgtT
Patient
Bennet C. et al. Curr Opin Pediatr,
2001 Gambineri E. et al. Curr Opin Rheumatol, 2003
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FOXP3 PROTEIN EXPRESSION by Flow Cytometry
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Proband
Normal donor
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FAMILY SCREENING
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I
1
2
II
5
4
1
2
3
6
7
III
3
2
1
5
Age 58 Chronic diarrhea since infancy
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6
Age 45 No symptoms reported
IV
4
2
1
6
7
3
5
Age 24 Gilbert Syndrome Mild eczema Ovaric
Polycistosis
V
Proband
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FAMILY SCREENING
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FOXP3 PROTEIN EXPRESSION by Flow Cytometry
CD4 gated
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ESEfinder
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Disruption of exonic splicing enhancer (ESE)
motifs and modification of SR protein binding
sites in mutated of FOXP3
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FOXP3 cDNA
FOXP3 cDNA fragments _at_ PCR amplification
cDNA

• Lower cDNA expression

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Conclusion Future Perspectives
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• In the majority of cases IPEX is a severe
  disease. Patients develop symptoms early in
  infancy and most die within the first 2 years of
  life. Milder and late-onset forms of the disease
  have been described.
• We found a family harboring a silent mutation
  within a splice site that do not alter protein
  expression but seems to affect mRNA
  transcription. Although only 2 members, among
  those with mutated FOXP3, manifest an incomplete
  form of IPEX with different disease severity.

IS IPEX UNDERESTIMATED OR MISDIAGNOSED? IS
REALLY FOXP3 RESPONSIBLE FOR THE DISEASE? WHAT
IS MODULATING THE PHENOTYPE VARIABILITY?
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Acknowledgments
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University of Florence, Department of Pediatrics
A. MEYER Childrens Hospital - Florence,
Italy Immunology Lab Gastroenterology
Unit Lucia Bianchi, PhD Paolo
Lionetti,MD Sara Ciullini Mannurita, BS
Francesca Bronzini,MD Anna Maria Grazia Gelli,
PhD Chiara Azzari, MD, PhD
Perroni Lucia - Genoa Tommasini Alberto -
Trieste Badolato Raffaele - Brescia Bacchetta
Rosa, Roncarolo Maria Grazia - Milan