Michiko Shiota

Tumor necrosis factor α 5′‐flanking region, tumor necrosis factor receptor II, and HLA–DRB1 polymorphisms in Japanese patients with rheumatoid arthritis

Objective New polymorphisms affecting transcriptional activity were recently reported within the 5′-flanking region of the tumor necrosis factor α gene (TNFA). In addition, genome-wide linkage screening indicated 1p36 as one of the candidate chromosomal regions where the TNF receptor II gene (TNFR2) is located. In the present study, HLA–DRB1, TNFA promoter, and TNFR2 genotypes were determined to examine whether these polymorphisms are associated with rheumatoid arthritis (RA), either independently or in combination. Methods Genotypes of HLA–DRB1, TNFA upstream promoter, and TNFR2 codon 196 were determined in 545 Japanese patients with RA and 265 healthy controls. Association of these genes with susceptibility to RA was analyzed both independently and after stratification by one of the genotypes. Results As expected, the HLA–DRB1 shared epitope was strongly associated with RA. In addition, a significant negative association of DRB1*1405 and 1302 was observed. Furthermore, DRB1*1405 was suggested to possess a protective role for the development of RA in DRB1*0405-positive individuals. A significant increase in TNFA-U02 in RA was detected, which was not independent of DRB1*0405. A significant association was not observed between TNFR2-196M/R polymorphism and RA. Conclusion Among the 3 genes examined in this study, HLA–DRB1 was considered to be most strongly associated with RA.

IDENTIFICATION OF THE GENE VARIATIONS IN HUMAN CD22

Abstract CD22, a member of the immunoglobulin superfamily, is a B-cell transmembrane glycoprotein that acts as an accessory-signaling component of the B-cell antigen receptor (BCR). Recent evidence indicating the role of CD22 as a negative regulator of BCR signal transduction prompted us to test the possibility that genetic variations of human CD22 may be associated with autoimmune diseases. In this study, variation screening of the entire CD22 coding region was performed, and possible association with rheumatic diseases was tested, using the genomic DNA from 207 healthy Japanese individuals, 68 patients with systemic lupus erythematosus (SLE), and 119 patients with rheumatoid arthritis (RA). Through the variation screening, seven non-synonymous and four synonymous substitutions were identified. In addition, single base substitutions were found in two introns flanking exon-intron junctions. Among these variations, Q152E substitution within the second extracellular domain was observed with a marginally higher frequency in the patients with SLE (3/68, 4.4%) than that in healthy individuals (1/207, 0.5%) (P=0.048. SLE vs healthy individuals), although this difference was no longer significant after correction for the number of comparisons (Pc=0.62). No significant association was observed between any of the variations and RA. These findings indicate that a number of genetic variants are present in CD22, and suggest that CD22 could be considered a candidate for the susceptibility genes to autoimmune diseases.

MICA allele typing of HLA-B27 positive Japanese patients with seronegative spondylarthropathies and healthy individuals : Differential linkage disequilibrium with HLA-B27 subtypes

OBJECTIVE To examine whether MICA (major histocompatibility complex [MHC] class I-related chain gene A) confers additional susceptibility for seronegative spondylarthropathies in HLA-B27 positive Japanese individuals. METHODS A polymerase chain reaction-single-strand conformation polymorphism method was developed, and the MICA alleles of 18 Japanese patients with ankylosing spondylitis, 1 patient with Reiters syndrome, and 17 healthy HLA-B27 positive Japanese subjects were determined. RESULTS Among 26 individuals with HLA-B*2704 (13 patients and 13 healthy subjects), all except 1 healthy individual were positive for MICA010, whereas all 9 HLA-B*2705 positive subjects (6 patients and 3 healthy subjects) possessed MICA007. One healthy individual with HLA-B*2711 also carried MICA010. CONCLUSION Strong linkage disequilibrium is present between HLA-B*2704 and MICA010, as well as between HLA-B*2705 and MICA007. Although HLA-B*2704 and B*2705 are highly homologous, each subtype participates in a different MHC haplotype. Direct involvement of MICA polymorphism in the pathogenesis seems to be unlikely; however, such information will provide a useful tool for elucidating the evolutional pathway of HLA-B27 subtypes as well as the contribution of other genes within the MHC region in the pathogenesis of these diseases.