Association of the single-nucleotide polymorphism and haplotype of the interleukin 18 gene with atopic dermatitis in Koreans.
BACKGROUND
IL-18 is a proinflammatory cytokine that plays an important role for T-helper type 1 (Th1) and Th2 cytokine in the presence/absence of IL-12. It has been recently shown that human IL-18 plays a role in atopic dermatitis (AD) by enhancing IL-4 and IL-13 production and by stimulating the synthesis of IgE.


OBJECTIVE
We wanted to evaluate the associations of single-nucleotide polymorphism (SNP) and the haplotype in the IL-18 gene, hence we performed genotyping for the SNPs in the IL-18 gene in AD patients and normal controls.


METHODS
We genotyped three SNPs from the IL-18 gene for the 1120 case-control samples (646 AD patients and 474 normal controls). We measured the serum IL-18, IL-4 and IL-13 concentrations in 74 individuals (25 ADe, 25 ADi and 24 controls) by performing ELISA.


RESULTS
The rs795467 SNP and haplotype T-T-C were significantly associated with AD, and especially between the ADe and normal control groups (P=0.03 and 0.01). The serum IL-18 concentration was higher in the AD group than in the normal controls without any correlation with the rs795467 polymorphism. We did not find any correlations between the serum IL-18 levels and the SCORing atopic dermatitis index, the blood eosinophil counts and the ECP, and there was no correlation between the serum IL-18 levels and the serum IL-4 and IL-13 levels.


CONCLUSIONS
We found that the one SNP and the haplotype T-T-C were strongly associated with the allergic type of AD, but not with the non-allergic intrinsic type. These data support the hypothesis that IL-18 up-regulates IgE production, yet more experiments will be needed to prove the in vivo involvement of Th2 cytokine.
Kim
E
E
Department of Dermatology, Sungkyunkwan University School of Medicine, Samsung Medical Center, Seoul, Korea.
Lee
J-E
JE
Namkung
J-H
JH
Park
J-H
JH
Kim
S
S
Shin
E-S
ES
Cho
E-Y
EY
Yang
J-M
JM
D000293:Adolescent; D000328:Adult; D044466:Asian People; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D003876:Dermatitis, Atopic / Q000097:blood / Q000235:genetics* / Q000276:immunology; D005260:Female; D006239:Haplotypes / Q000235:genetics* / Q000276:immunology; D006801:Humans; D007073:Immunoglobulin E / Q000097:blood / Q000276:immunology; D018664:Interleukin-12 / Q000097:blood / Q000276:immunology; D018793:Interleukin-13 / Q000097:blood / Q000276:immunology; D020382:Interleukin-18 / Q000097:blood / Q000235:genetics* / Q000276:immunology; D015847:Interleukin-4 / Q000097:blood / Q000276:immunology; D007723:Korea; D008297:Male; D020641:Polymorphism, Single Nucleotide; D018417:Th1 Cells / Q000276:immunology; D018418:Th2 Cells / Q000276:immunology; D015854:Up-Regulation / Q000235:genetics / Q000276:immunology
C508598:IL4 protein, human; D018793:Interleukin-13; D020382:Interleukin-18; D018664:Interleukin-12; D015847:Interleukin-4; D007073:Immunoglobulin E