Anti-carbamylated protein antibody isotype pattern differs between palindromic rheumatism and rheumatoid arthritis. (December 2020)

• Record Type: Journal Article
• Authors: Castellanos-Moreira, Raul; Rodriguez-Garcia, Sebastian C.; Cabrera-Villalba, Sonia; Gomara, María José; Salvador, Georgina; Ruiz-Esquide, Virginia; Ramirez, Julio; Inciarte-Mundo, Jose; Morla, Rosa; Garcia-Moreno, Cristina; Cuervo, Andrea; Gómez-Puerta, Jose A.; Cañete, Juan D.; Haro, Isabel; Sanmarti, Raimon
• Is Part Of: Therapeutic advances in musculoskeletal disease. Volume 12(2020)
• Publication Date: 2020-12
• Subjects: ACPA -- Anti-CarP -- autoantibodies -- B cells -- palindromic rheumatism -- rheumatoid arthritis; Musculoskeletal system -- Diseases -- Periodicals; Musculoskeletal Diseases -- Periodicals; 616.7
• DOI: 10.1177/1759720X20978139
• Languages: English
• ISSNs: 1759-720X

Abstract

Background: A restricted response against citrullinated peptides/proteins, with less isotype usage, has been found in palindromic rheumatism (PR) in comparison with rheumatoid arthritis (RA). We hypothesized that this different antibody response may be observed for other post-translational modified proteins. We compared the prevalence and isotype usage of two specificities of anti-carbamylated peptide/protein antibodies (Anti-CarP) in patients with PR and RA. Methods: Cross-sectional study including 54 patients with pure PR and 53 patients with RA, matched by sex, age, disease duration and ACPA. Anti-CarP specificities were determined by home-made enzyme-linked immunosorbent assay tests using a synthetic chimeric fibrin/filaggrin homocitrullinated peptide (CFFHP) and fetal calf serum (FCS) homocitrullinated protein as antigens. IgG, IgA and IgM isotypes were measured. Results: Anti-CarP were positive (CFFHP or FCS) in 24% and 64% of patients with PR and RA, respectively ( p < 0.005). All Anti-CarP isotype proportions were significantly lower in PR than in RA: Anti-CarP-IgG (24% versus 51%), Anti-CarP-IgA (7% versus 34%) and Anti-CarP-IgM (7% versus 36%). Mean titers of Anti-CarP isotypes were also lower in PR. In Anti-CarP positive patients, the isotype distribution differed between PR and RA: IgG Anti-CarP was used in all PR patients and in 79% of RA patients. By contrast, a significantly lower isotype usage of both IgA (31% versus 53%) and IgM (31% versus 56%) was observed in PR patients. No significant differences in clinical or demographic characteristics were observed according to Anti-CarP status in PR patients, except for a higher prevalence of ACPA and higher mean titers of ACPA and rheumatoid factor in Anti-CarP positive patients. Conclusion: Anti-CarP are found in patients with PR but in a lower proportion and with a different isotype usage from in RA, suggesting a distinct B cell response to homocitrullinated antigens in PR.