Anti-citrullinated glucose-6-phosphate isomerase peptide antibodies in patients with rheumatoid arthritis are associated with HLA-DRB1 shared epitope alleles and disease activity

Department of Internal Medicine, Faculty of Medicine, University of Tsukuba, Tsukuba, Japan.
Clinical & Experimental Immunology (Impact Factor: 3.04). 04/2013; 172(1):44-53. DOI: 10.1111/cei.12033
Source: PubMed


To identify and characterize anti-citrullinated glucose-6-phosphate isomerase (GPI) peptide antibodies in patients with rheumatoid arthritis (RA). Nine GPI arginine-bearing peptides in human GPI protein were selected and cyclic citrullinated GPI peptides (CCG-1-9) were constructed. Samples were obtained from RA (n = 208), systemic lupus erythematosus (SLE) (n = 101), Sjögren's syndrome (SS; n = 101) and healthy controls (n = 174). Antibodies against CCG-1-9 were measured, and anti-citrullinated α-enolase-1 (CEP-1), -cyclic citrullinated peptides (CCP) and -GPI proteins antibodies were also examined. Patients with RA were genotyped for HLA-DRB1. The numbers of shared epitope (SE) alleles were counted and compared with those of the autoantibodies. Rabbit GPI was citrullinated with rabbit peptidylarginine deiminase and immunoblot analysis of RA sera performed. The levels of autoantibodies were compared before and after treatment with TNF antagonists in 58 RA patients. Anti-CCG-2, -4 and -7 antibodies were detected in 25·5, 33·2 and 37·0% patients with RA, respectively, and these antibodies were very specific for RA (specificity, 98·1-99·7%). Altogether, 44·2, 86·1 and 13·9% of RA sera were positive for anti-CEP-1, -CCP and -GPI protein antibodies, respectively. Anti-CCG-2, -4 and -7 antibodies were correlated with anti-CCP and anti-CEP-1 antibodies and with the presence of HLA-DRB1 SE alleles. Citrullinated GPI protein was detected using RA sera. Treatment with tumour necrosis factor antagonists reduced significantly the levels of anti-CCG-2 and -7 but not of anti-CEP-1 antibodies. This is the first report documenting the presence of anti-CCG antibodies in RA. Anti-CCG-2 and -7 antibodies could be considered as markers for the diagnosis of RA and its disease activity.

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    • "However, the presentation of intracellular citrullinated proteins in the synovium is specific for RA (Baeten et al., 2001), and is colocalized with PADI2 (De Rycke, 2005). Numerous well-known or suspected intracellular substrates of PADI2 and PADI4 exist, such as vimentin (Asaga et al., 1998; Vossenaar et al., 2004b), histones (Nakashima et al., 2002), nucleophosmin/B23 (Hagiwara et al., 2002), the F-actin capping protein alpha 1 subunit, cathepsin D, beta-actin (Matsuo et al., 2006), aldolase, alpha-enolase, phosphoglyce-rate kinase 1, calreticulin, the 60-kDa heat shock protein, far upstream element-binding proteins 1 and 2 (Goëb et al., 2009), glucose-6-phosphate isomerase (Umeda et al., 2013), and IKKγ (Lee et al., 2010). Among these, vimentin is the major citrullinated protein in human monocytic leukemia THP-1 cells during macrophage differentiation (Hojo-Nakashima et al., 2009). "
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    ABSTRACT: Peptidylarginine deiminase type 2 (PADI2) deiminates (or citrullinates) arginine residues in protein to citrulline residues in a Ca2+-dependent manner, and is found in lymphocytes and macrophages. Vimentin is an intermediate filament protein and a well-known substrate of PADI2. Citrullinated vimentin is found in ionomycin-induced macrophage apoptosis. Citrullinated vimentin is the target of anti-Sa antibodies, which are specific to rheumatoid arthritis, and play a critical role in the pathogenesis of the disease. To investigate the role of PADI2 in apoptosis, we generated a Jurkat cell line that overexpressed the PADI2 transgene from a tetracycline-inducible promoter, and used a combination of 12-O-tetradecanoylphorbol-13-acetate and ionomycin to activate Jurkat cells. We found that PADI2 overexpression reduced the cell viability of activated Jurkat cells in1a dose- and time-dependent manner. The PADI2-overexpressed and -activated Jurkat cells presented typical manifestations of apoptosis, and exhibited greater levels of citrullinated proteins, including citrullinated vimentin. Vimentin overexpression rescued a portion of the cells from apoptosis. In conclusion, PADI2 overexpression induces apoptosis in activated Jurkat cells. Vimentin is involved in PADI2-induced apoptosis. Moreover, PADI2-overexpressed Jurkat cells secreted greater levels of vimentin after activation, and expressed more vimentin on their cell surfaces when undergoing apoptosis. Through artificially highlighting PADI2 and vimentin, we demonstrated that PADI2 and vimentin participate in the apoptotic mechanisms of activated T lymphocytes. The secretion and surface expression of vimentin are possible ways of autoantigen presentation to the immune system.
    Full-text · Article · May 2014 · Molecules and Cells
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    ABSTRACT: To describe recent progress concerning Rheumatoid Arthritis (RA) associated autoantibodies, in particular antibodies to citrullinated proteins antigens. An increasingly diverse and RA-associated repertoire of antibodies has been defined over the last few years. These antibodies are preferentially, but not exclusively, reactive with posttranslationally modified antigens. Citrullinated antigens are the most common targets, but also other modifications including homocitrullination (carbamylation) are recognized. These antibodies display varying degrees of cross-reactivity, and both broadly cross-reactive and monoreactive antibodies are present. Progress, described in this review, has been made both concerning mechanisms behind the generation of these antibodies and concerning their effector functions. Several different triggering mechanisms are involved in forming an antibody repertoire that evolves before the onset of clinical disease, and where antibodies with different specificities may interact directly or indirectly with target organs in causing different arthritis-associated symptoms. The increasing understanding of the role of adaptive and specific immunity in RA creates opportunities for a new generation of interventions.
    Full-text · Article · Nov 2013 · Current opinion in rheumatology
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    ABSTRACT: Aims: To construct and evaluate rats' tolerogenic dendritic cells (DC) through induction by NF-κB Decoy method. Methods: GM-CSF and IL-4 were used to transform rats's monocytes into DC, and DC were stimulated with LPS, NF-κB Decoy ODN, and loaded with Bovine Type II Collagen. The following methods were employed to phenotype DC: 1) Observation of cell morphology; 2) Evaluation of cell viability using trypan blue staining; 3) Purity determination of DC through detection of specific markers OX-62; 4) Evaluation of mature state of DC via the determination of the expression of CD80 and CD86; 5) Determination of stimulation capability towards the proliferation of lymphocyte and the secretion of INF-r and IL-10. Results: The activity of DC was more than 92%, and the expression of OX-62 was more than 70%. Most of DC exhibited the phenotype of CD80(+)/CD86(-). Compared with control group and LPS-stimulation group, the less mature adhered cells and hairlike DC were observed in NF-κB decoy group. Significant reduction (p < 0.05) was observed for the positive expression and extension of CD80 and CD86 in cell surface. After loaded with calf type II collagen, the low expression of CD80 and CD86 remains to be existed. The stimulation capability of DC towards lymphocyte in NF-κB decoy group was lower than that in control group (p<0.05) and LPS stimulation group (p < 0.05). Conclusion: NF-κB Decoy ODN method can be successfully applied for construct rats' tolerogenic dendritic cells (DC) with stable morphology and phenotype. The tolerogenic DC exhibited immature immune phenotype, and low capability to stimulate lymphocytes.
    Preview · Article · Sep 2014 · African Health Sciences
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