FCGR2B) Is Associated with the Production of Anti-Cyclic Citrullinated Peptide Autoantibodies in Taiwanese RA
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Genes and Immunity (2008) 9, 680–688 & 2008 Macmillan Publishers Limited All rights reserved 1466-4879/08 $32.00 www.nature.com/gene ORIGINAL ARTICLE A transmembrane polymorphism in FcgRIIb (FCGR2B) is associated with the production of anti-cyclic citrullinated peptide autoantibodies in Taiwanese RA J-Y Chen1, C-M Wang2, C-C Ma1, L-A Hsu3, H-H Ho1, Y-JJ Wu1, S-N Kuo1 and J Wu4 1Division of Allergy, Immunology and Rheumatology, Department of Medicine, Chang Gung Memorial Hospital, Chang Gung University College of Medicine, Tao-Yuan, Taiwan, Republic of China; 2Department of Rehabilitation, Chang Gung Memorial Hospital, Chang Gung University College of Medicine, Tao-Yuan, Taiwan, Republic of China; 3Department of Medicine, Division of First Cardiovascular, Chang Gung Memorial Hospital, Chang Gung University College of Medicine, Tao-Yuan, Taiwan, Republic of China and 4Division of Clinical Immunology and Rheumatology, Department of Medicine, University of Alabama at Birmingham, Birmingham, AL, USA The aim of the current study was to determine whether the FcgRIIb 187-Ile/Thr polymorphism is a predisposition factor for subtypes of RA defined by disease severity and production of autoantibodies against cyclic citrullinated peptides (anti-CCPs) in Taiwanese RA patients. Genotype distributions and allele frequencies of FcgRIIb 187-Ile/Thr were compared between 562 normal healthy controls and 640 RA patients as stratified by clinical parameters and autoantibodies. Significant enrichment of 187-Ile allele was observed in RA patients positive for anti-CCP antibodies as compared with the anti-CCP negative RA patients (P ¼ 0.001, OR 1.652 (95% CI 1.210–2.257)) or as compared with the normal controls (P ¼ 0.005, OR 1.348 (95% CI 1.092–1.664)). In addition, 187-Ile allele was found to be enriched in RA patients positive for rheumatoid factor (RF) compared to the RF negative RA patients (P ¼ 0.024, OR 1.562 (95% CI 1.059–2.303)). Furthermore, the homozygotes were enriched in destructive male RA patients (P ¼ 0.035; OR 2.038 (95% CI 1.046–3.973)) and the 187-Ile allele was associated with early- onset of RA in Taiwanese patients (P ¼ 0.045, OR 1.548 (95% CI 1.007–2.379)). Thus, FcgRIIb SNP 187-Ile/Thr may influence the RA phenotypes in Taiwanese RA. Genes and Immunity (2008) 9, 680–688; doi:10.1038/gene.2008.56; published online 17 July 2008 Keywords: rheumatoid arthritis; anti-CCP antibody; FcgR; polymorphism Introduction aid the treatment of those patients with early aggressive Disease Modifying Anti-Rheumatic Drugs that could Rheumatoid arthritis (RA) is a chronic inflammatory thwart the progression of the pathologic process. disease characterized by joint inflammation, infiltration of Immunoglobulin molecules mediate various immune- immune cells, proliferation of synovial cells, destruction of related functions including phagocytosis, degranulation, cartilage and bony erosion in multiple joints. The functional antibody-dependent cell-mediated cytotoxicity, cytokine disability caused by RA leads to severe work and daily release and antigen presentation through binding of their living disturbance. Although the precise etiology and Fc portions to specific cell surface receptors. In humans, pathogenesis remain incompletely understood, multiple eight genes (FcgRIA, FcgRIB, FcgRIC, FcgRIIA, FcgRIIB, factors including genetic composition, possible infection FcgRIIC, FcgRIIIA and FcgRIIIB) encoding the classical Fcg triggering and other immune dysfunction all are thought to receptors are clustered in the 1q21-23 region of chromo- contribute to RA pathogenesis.1 The important contribution some 1. Polymorphisms in human FcgR genes signifi- of genetic factors in RA development was demonstrated by cantly affect the receptor functions and play important twin and genome-scan studies.2–6 The identification of roles in modulating the immune response and in the genetic factors associated with destructive forms of RA will pathogenesis of autoimmune diseases.7,8 FcgRIIb (CD32B) is generally considered as an inhibi- tory Fcg receptor in both humans and mice.9–11 Cross- Correspondence: Dr J-Y Chen, Division of Allergy, Immunology and linking of FcgRIIb leads to the downregulation of B-cell Rheumatology, Department of Medicine, Chang Gung Memorial Hospital, Chang Gung University College of Medicine, No. 5, activation and immunoglobulin production and there- Fu-Shin St Kuei-Shan, Tao-Yuan, Taiwan 333, Republic of China. fore, FcgRIIb is the major receptor that provides feedback E-mail: [email protected] or inhibitory signals for cell activation by immune com- Dr J Wu, Division of Clinical Immunology and Rheumatology, plexes.9,11,12 On the other hand, myeloid cells (monocytes Department of Medicine, University of Alabama at Birmingham, Shelby and neutrophils) and follicular dendritic cells also 202, 1825 University Boulevard, Birmingham, AL 35294-2182, USA. express FcgRIIb. FcgRIIb on follicular dendritic cells is E-mail: [email protected] 13–16 Received 28 April 2008; revised 16 June 2008; accepted 18 June 2008; critical to mediate B cell recall responses. Therefore, published online 17 July 2008 FcgRIIb has multiple functions in different cell systems. Association of FccRIIb polymorphism with anti-CCP antibody in RA J-Y Chen et al 681 FcgRIIb 187-Ile/Thr polymorphism (rs1050501) is trends toward the increased 187-Ile homozygosity and located in the transmembrane segment of the receptor the increased 187-Ile allele frequency in RA patients as and the amino acid change significantly affects receptor- compared with those in normal healthy controls, but mediated functions.17–19 We hypothesize that this func- these increases did not reach statistical significance tional polymorphism might play an important role in the (P ¼ 0.098 and P ¼ 0.138 respectively). pathogenesis of human rheumatoid arthritis. In the current study, we demonstrated that FcgRIIb 187-Ile The common 187-Ile allele is associated with anti-CCP þ RA allele (the allele mediating more potent inhibitory signal Anti-CCP antibodies are highly specific for RA and are and the allele being more effectively recruited to lipid predictive of the progression of undifferentiated arthritis rafts) is significantly associated with anti-CCP antibody toward RA.21,22 In addition, anti-CCP antibodies are production, RF production, destructive RA and early associated with erosive disease in RA patients.23 To onset of RA in Taiwanese patients. Our observations may determine whether FCGR2B SNP c775T4C is associated provide new insights into the role of FcgRIIb in the with production of anti-CCP antibodies; we stratified RA pathogenesis of human RA and other human autoim- patients based on presence and absence of anti-CCP mune diseases driven by autoantibody production and antibodies. Among 595 RA patients assayed for anti-CCP immune complex formation. antibodies, 464 patients (78.0%) were positive for anti- CCP þ (titers X40 IU mlÀ1). As shown in Table 2, we observed significant differences in the genotype distribu- tion between anti-CCP þ and anti-CCPÀ RA patients Results (3 Â 2 contingency table, w2 ¼ 9.819, P ¼ 0.007). The 187-Ile Demographic and clinical characteristics of rheumatoid homozygous donors were significantly increased in anti- arthritis in Taiwan CCP þ RA patients compared with anti-CCPÀ RA The present study cohort included 550 female and patients (P ¼ 0.003, odds ratio 1.819 (95% CI 1.229– 90 male Taiwanese RA patients with a mean age±s.d. 2.691)). Multiple variable logistic regression analysis at RA disease onset of 46.5±13.4 years (range, 10–80). adjusted for age, sex, anti-CCP antibody, RF and These RA patients had the mean disease duration of ANA revealed significant enrichment of the 187-Ile 13.4±8.0 years and had been followed up for at least 2 homozygotes in anti-CCP þ RA patients as compared years to assess the disease course. Five hundred and ten with anti-CCPÀ patients (P ¼ 0.007, odds ratio 1.876 (95% of the total 640 RA patients (79.7%) were positive for CI 1.187–2.965)) (Table 2). The 187-Ile allele frequency rheumatoid factor (RF). Among 574 RA patients assayed was also significantly increased in anti-CCP þ RA for antinuclear antibodies (ANA), 308 patients (53.7%) patients compared with anti-CCPÀ RA patients were positive for ANA (titers X1:80). Based on X-ray (P ¼ 0.001 odds ratio 1.652 (95% CI 1.210–2.257)). Ad- radiography data of hands and wrist joints, 513 patients ditionally, we observed a significant enrichment of 187- displayed bony erosion (X ray stage XII), 401 patients Ile allele in anti-CCP þ RA patients as compared with demonstrated destruction of joint subluxation and/or normal healthy controls (P ¼ 0.005; odds ratio 1.348 (95% ankylosis (X ray stage XIII) and 204 patients documen- CI 1.092–1.664)) and a significant enrichment of 187-Ile ted cervical spine involvement. homozygotes in anti-CCP þ RA patients as compared In the current study, 640 Taiwanese RA patients and with normal controls (w2 ¼ 7.920, P ¼ 0.005; odds ratio 562 healthy controls were genotyped using the MALDI- 1.438 (95% CI 1.116–1.852)). Our data suggest that 187-Ile TOF genotyping method for FCGR2B SNP c775T4C. The allele is an important genetic risk factor for anti-CCP reliability of the genotyping with MALDI-TOF was antibody production in Taiwanese RA patients. confirmed as described previously.20 We did not observe any significant deviations from Hardy–Weinberg equili- Association of 187-Ile allele with rheumatoid factor production brium in RA patients (w2 ¼ 0.580, P ¼ 0.748) and in the in RA patients normal controls (w2 ¼ 0.000, P ¼ 1.00) by 3 Â 2 contin- Human rheumatoid arthritis patients produce a range of gency table analyses. As shown in Table 1, there were autoantibodies including antibodies against Fc portion of Table 1 Distribution of genotypes and allele frequencies of FcgRIIb 187-Ile/Thr polymorphism in Taiwanese normal controls and RA patients Controls (N ¼ 562) RA patients (N ¼ 640) OR (95% CI) P-value Genotype frequency, no.