Physiologic Target, Molecular Evolution, and Pathogenic Functions of a Monoclonal Anti–Citrullinated Protein Antibody Obtained From a Patient With Rheumatoid Arthritis

Autor: Atsushi Muraguchi, Hirofumi Taki, Kazuyuki Tobe, Reina Tsuda, Hiroki Kohno, Hidemi Kurihara, Eiji Kobayashi, Hiroyuki Kishi, Hiroshi Hamana, Tatsuhiko Ozawa, Eiji Sugiyama, Kazuhisa Ouhara, Syuichi Munenaga
Rok vydání: 2020
Předmět:
Zdroj: Arthritis & Rheumatology. 72:2040-2049
ISSN: 2326-5205
2326-5191
DOI: 10.1002/art.41426
Popis: OBJECTIVE In plasma from a patient with rheumatoid arthritis (RA), we previously isolated a human monoclonal anti-citrullinated protein antibody (ACPA), CCP-Ab1, that recognizes various citrullinated antigens. In this study, we aimed to explore the physiologic target of CCP-Ab1 and the role of molecular evolution, through affinity maturation, of this ACPA in the onset and the exacerbation of RA. METHODS The target protein of CCP-Ab1 was identified in the plasma of a patient with RA and purified under native conditions. Germline-reverted (GL-rev) CCP-Ab1 was generated, and its reactivity was compared to that of mature CCP-Ab1. The functions of CCP-Ab1 and GL-rev CCP-Ab1 in the onset or exacerbation of autoimmune arthritis were analyzed using autoimmune arthritis-prone SKG mice. RESULTS CCP-Ab1 bound citrullinated fibrinogen under native conditions. In cultures with GL-rev CCP-Ab1, the binding affinity to citrullinated fibrinogen was drastically reduced (P < 0.05). The elements implicated in GL-rev CCP-Ab1 binding to a citrullinated peptide, cfc1-cyc, were almost identical to those implicated in CCP-Ab1 binding. In arthritis-prone SKG mice, CCP-Ab1, but not GL-rev CCP-Ab1, induced significant exacerbation of experimental arthritis (P < 0.05). Increased production of interleukin-6, both in the joint tissue and in the serum, was observed in SKG mice treated with CCP-Ab1 compared to those treated with GL-rev CCP-Ab1 (P < 0.05). Furthermore, the immune complex formed by CCP-Ab1 and fibrinogen was detected at higher concentrations in the synovial tissue of SKG mice administered CCP-Ab1 (P < 0.05 versus control treatment groups). CONCLUSION These data show that germline-encoded CCP-Ab1, which binds weakly to citrullinated fibrinogen, undergoes hypermutation through the activation of naive B cells by citrullinated peptides/proteins, thereby stimulating high reactivity to citrullinated fibrinogen. These findings deepen our understanding of the role of molecular evolution of ACPAs in the onset and exacerbation of RA.
Databáze: OpenAIRE
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