Download - Eczema in children Hugo Van Bever
Eczema in children
Hugo Van BeverDepartment of Pediatrics
National University Singapore
APAPARI Workshop, Hanoi, May 2008
Mechanisms of Eczema in Children
1. ALLERGY
2. SKIN BARRIER DYSFUNCTIONS
?
Kalliomaki M, Lancet. 2001; 357:1076
Incidence of eczema at 2 years in children given probiotics from birth
50% decrease…
IgE-mediated reactions persist !
AD and BMT
1. Complete correction of the Wiskott-Aldrich syndrome by allergenic bone-marrow transplantation. Parkman et al.
NEJM 1978, 298, 921.
2. Transfer of atopy following bone marrow transplantation. Bellou A, et al. Ann Allergy Asthma Immunol 1997, 78, 513.
Atopic dermatitis
1. SKIN DISORDER
2. ALLERGIC DISEASE
3. Combination ?
Eczema in Singapore ChildrenResults of ISAAC Questionnaire Survey
1 year period prevalence of 20.8% from a questionnaire cum clinical examination survey in schoolchildren
(Tay YK et al Br J Dermatol 2002)
Wang XS et al. Arch Dis Child. 2004, Tan TN et al., Pediatr Allergy Immunol. 2005, Asian Pac J Allergy Immunol. 2006
The Asian Skin 1. Ethnic differences in the pattern of skin diseases seen in a
dermatology department – atopic dermatitis is more common among Asian referrals in Leicestershire. Sladden et al. Clin Exp Dermatol 1991, 16, 348.
2. The effect of lifestyle on wheeze, atopy, and bronchial hyperreactivity in Asian and white children. Carey et al. Am J Respir Crit Care Med. 1996, 154, 537.
3. Atopic dermatitis in children in the United States, 1997 – 2004: visit trends, patient and provider characteristics, and prescribing patterns. Horii et al. Pediatrics 2007, 120, e527.
AD in Asians…
1. more common2. more severe (?)
Eczema
SKIN BARRIER DYSFUNCTIONS
New perspectives on epidermal barrier dysfunction in atopic dermatitis: Gene–environment interactions.
Michael J Cork et al. J Allergy Clin Immunol 2006, 118, 3 – 21.
“… on the importance of epidermal barrier dysfunction in genetically predisposed individuals …”
Skin barrier dysfunction in AD
1. dry skin – increased transepidermal water loss
2. reduced content of ceramides
3. changes in stratum corneum pH level
4. overexpression of chymotryptic enzyme“ Stratum corneum chymotryptic enzyme (SCCE) “
5. altered keratinocyte cytokine profile
1. Chymotrypsin (SCCE)
2. Filaggrin
Two (of the many) new players in eczema…
Filaggrin gene
- FLG is located within “the epidermal differentiation complex (EDC) on chromosome 1q21.
- Function: to aggregate keratin filaments formation of stratum corneum maintaining the barrier function of the skin.
- Associated with ichtyosis, AD, and psoriasis
FLG polymorphisms R501X
228del4
Complete loss of FLG expression
ICHTHYOSIS VULGARIS
(= FLG null alleles)
Phenotype(ECZEMA)
Environment Genes
DEVELOPMENT(EPIGENETICS)
Dynamics of gene expression(methylation processes)
Area of new research…
Impaired skin epidermal barrier
allergen penetration IgE
ALLERGIC MARCH
Eczema severity AsthmaRhinitis
(different type of allergy?)
= 2nd event…
Extrinsic versus intrinsic eczema
IgE
Altered skin barrier
EXT
INT
AD
AD: 2 features
severe
allergy
severity of AD
Skin barrier features
allergy
The environment
The rising prevalence of atopic eczema and environmental trauma to the skin.
Cork et al. Dermat Pract 2002, 10, 22.
UK data 1960 - 1981 1995 - 2001
Personal use of soap -detergent 76 million £ 453 million £
Water for personal washing 11 L /day 51 L/day
Increased skin barrier dysfunctions
Pathogenesis of AD
SKIN BARRIER DYSFUNC
TIONS
ALLERGY
genesgenesenvironment
environment
ECZEMA
HYPOTHETIC MODEL OF AD
PHASE 1: Non-allergic inflammation- ichtyosis – pruritus- auto-immunity (?)
PHASE 2: Allergic inflammation- food ( through urticaria)- inhalants
PHASE 3: Infectious inflammation- Staph colonization- Viral colonization
early infancy
early childhood
late childhoodadulthood
HYPOTHETIC MODEL OF AD
PHASE 1: Non-allergic inflammation- ichtyosis – pruritus- auto-immunity (?)
PHASE 2: Allergic inflammation- food ( through urticaria)- inhalants
PHASE 3: Infectious inflammation - Staph colonization
- Viral colonization
early infancy
early childhood
late childhoodadulthood
moisturizing
allergen avoidance
antiseptics > antibiotics