Rheumatoid Arthritis: Anzilotti C

Migliorini P, Pratesi F, Tommasi C, Anzilotti C. · Clinical Immunology Unit, Department of Internal Medicine, University of Pisa, Italy. · Autoimmun Rev. · Pubmed #16214096 No free full text.

Abstract: Post-translational modifications of proteins occur very frequently. One of these modifications, citrullination, is the result of arginine deimination operated by an enzyme, peptidylarginine deiminase (PAD), whose activity is under strict genetic control. Serum antibodies reactive with citrullinated proteins/peptides are a very sensitive and specific marker for rheumatoid arthritis. Genes encoding for PAD enzymes have been investigated in RA: the PADI4 gene confers susceptibility to RA in Japanese patients, but not in Caucasians.

Anzilotti C, Riente L, Pratesi F, Chimenti D, Delle Sedie A, Bombardieri S, Migliorini P. · Clinical Immunology Unit, Department of Internal Medicine, University of Pisa, Pisa, Italy. · Rheumatology (Oxford). · Pubmed #17717033 No free full text.

Abstract: OBJECTIVES: Anti-citrullinated protein/peptide antibodies (ACPA), a family of antibodies with overlapping specificities, represent a specific marker of rheumatoid arthritis (RA). The aim of the present study is to investigate the prevalence and clinical significance of IgG, IgA and IgM ACPA by a newly described assay employing a viral citrullinated peptide (VCP). METHODS: IgG, IgA and IgM anti-VCP antibodies have been measured in sera from 146 patients affected by RA and 404 controls, including 204 chronic arthritides, 111 connective tissue disorders and 89 healthy subjects. The affinity of the different isotypes for VCP was analysed by liquid phase inhibition assays. RESULTS: Among RA patients, 40 were single positive for IgG anti-VCP, five for IgA and 11 for IgM. Ten patients were double positive for IgG and IgA, four for IgG and IgM, six for IgA and IgM. In 15 RA patients IgG, IgA and IgM anti-VCP antibodies were detected. No correlation could be found between the isotype and the clinical manifestations or duration of the disease. IgA anti-VCP were strongly associated with RA, whereas IgM anti-VCP were detected also in a low percentage of systemic lupus erythematosus, psoriatic arthritis and mixed cryoglobulinaemia (MC) patients. IgG anti-VCP displayed a higher affinity for the antigen than IgA or IgM. CONCLUSIONS: These data show that anti-VCP of IgG and IgA isotype discriminate RA from other chronic arthritides and disease controls and suggest an independent production of each isotype.

Anzilotti C, Merlini G, Pratesi F, Tommasi C, Chimenti D, Migliorini P. · Clinical Immunology Unit, Department of Internal Medicine, University of Pisa, Pisa, Italy. · J Rheumatol. · Pubmed #16511941 No free full text.

Abstract: OBJECTIVE: To analyze the frequency of anti-viral citrullinated peptide (anti-VCP) antibodies in sera from patients with rheumatoid arthritis (RA) by an Epstein-Barr virus (EBV)-derived peptide in which arginine is replaced with citrulline.METHODS: Anti-VCP antibodies were determined in 627 serum samples, 300 from patients with RA and 327 from controls, including connective tissue diseases, chronic arthritides, and healthy donors. Among patients with RA, a possible correlation with systemic involvement, disease severity, and disease activity was investigated; in 94 RA patients antibodies to cyclic citrullinated protein (anti-CCP) were also measured. RESULTS: Anti-VCP antibodies were found in 45% of RA sera versus less than 5% of controls; anti-VCP levels correlated with anti-CCP levels (p < 0.0001), rheumatoid factor (p = 0.02), and erythrocyte sedimentation rate (p = 0.0058). No correlation was found with extraarticular manifestations of the disease or with disease severity. CONCLUSION: Anti-VCP antibodies are helpful in discriminating RA from other chronic arthritides or connective tissue disorders. The level of positivity is positively correlated with the anti-CCP level, suggesting that VCP can be considered a novel substrate to detect anti-citrullinated peptide/protein antibodies (ACPA). The reactivity of RA-specific antibodies with a viral citrullinated antigen raises questions on the role of EBV in the induction of ACPA.

Pratesi F, Tommasi C, Anzilotti C, Chimenti D, Migliorini P. · University of Pisa, Pisa, Italy. · Arthritis Rheum. · Pubmed #16508937 links to  free full text

Abstract: OBJECTIVE: To test the hypothesis that deimination of viral sequences containing Arg-Gly repeats could generate epitopes recognized by anti-citrullinated protein antibodies (ACPAs) that are present in rheumatoid arthritis (RA) sera. METHODS: Multiple antigen peptides derived from Epstein-Barr virus (EBV)-encoded Epstein-Barr nuclear antigen 1 (EBNA-1) were synthesized, substituting the arginines with citrulline, and were used to screen RA sera. Anti-cyclic citrullinated peptide antibodies were purified by affinity chromatography and tested on a panel of in vitro deiminated proteins. Their ability to bind in vivo deiminated proteins was evaluated by immunoprecipitation, using EBV-infected cell lines. RESULTS: Antibodies specific for a peptide corresponding to the EBNA-1(35-58) sequence containing citrulline in place of arginine (viral citrullinated peptide [VCP]) were detected in 50% of RA sera and in <5% of normal and disease control sera. In addition, affinity-purified anti-VCP antibodies from RA sera reacted with filaggrin-derived citrullinated peptides, with deiminated fibrinogen, and with deiminated recombinant EBNA-1. Moreover, anti-VCP antibodies immunoprecipitated, from the lysate of calcium ionophore-stimulated lymphoblastoid cell lines, an 80-kd band that was reactive with a monoclonal anti-EBNA-1 antibody and with anti-modified citrulline antibodies. CONCLUSION: These data indicate that ACPAs react with a viral deiminated protein and suggest that EBV infection may play a role in the induction of these RA-specific antibodies.

Merlini G, Anzilotti C, Chimenti D, Tommasi C, Bombardieri S, Migliorini P. · Clinical Immunology Unit, Department of Internal Medicine, Via Roma 67, 56126 Pisa, Italy. · Ann N Y Acad Sci. · Pubmed #16014539 No free full text.

Abstract: The data presented suggest that a deiminated viral peptide is specifically recognized by antibodies contained in rheumatoid arthritis (RA) sera. Antipeptide antibodies are not associated with the presence or severity of specific manifestations of RA, but are more frequent in subjects with erosive arthritis. Taking into account the association with rheumatoid factor and with erosive arthritis, we can conclude that antipeptide antibodies are markers of severe forms of RA. Our data also show familial aggregation of anticitrullinated peptide antibodies.