Immunization with Porphyromonas gingivalis enolase induces autoimmunity to mammalian α-enolase and arthritis in DR4-IE-transgenic mice

Abstract

Objective. To examine the hypothesis that the subset of rheumatoid arthritis (RA) characterized by antibodies to citrullinated ␣-enolase is mediated by Porphyromonas gingivalis enolase in the context of DR4 alleles.Methods. Recombinant human ␣-enolase and P gingivalis enolase, either citrullinated or uncitrullinated, were used to immunize DR4-IE-transgenic mice and control mice (class II major histocompatibility complex-deficient [class II MHC ؊/؊ ] and C57BL/6 wild-type mice). Arthritis was quantified by measurement of ankle swelling in the hind paws and histologic examination. Serum IgG reactivity with ␣-enolase and citrullinated ␣-enolase was assayed by Western blotting and enzyme-linked immunosorbent assay (ELISA). Antibodies to peptide 1 of citrullinated ␣-enolase (CEP-1) and its arginine-bearing control peptide, REP-1, were also assessed by ELISA.Results. Significant hind-ankle swelling (>0.3 mm) occurred in DR4-IE-transgenic mice immunized with citrullinated human ␣-enolase (9 of 12 mice), uncitrullinated human ␣-enolase (9 of 12 mice), citrullinated P gingivalis enolase (6 of 6 mice), and uncitrullinated P gingivalis enolase (6 of 6 mice). Swelling peaked on day 24. None of the control groups developed arthritis. The arthritic joints showed synovial hyperplasia and erosions, but there was a paucity of leukocyte infiltration. Antibodies to human ␣-enolase, both citrullinated and unmodified, and to CEP-1 and REP-1 were detectable in all immunized mice except the class II MHC ؊/؊ control mice.Conclusion. This is the first animal model that links an immune response to P gingivalis enolase to an important subset of RA, defined by antibodies to citrullinated ␣-enolase in the context of DR4. The fact that arthritis and anti-CEP-1 antibodies were induced independent of citrullination of the immunizing antigen suggests that the unmodified form of ␣-enolase may be important in initiating the corresponding subset of human RA.

Human α‐enolase is immunogenic, but not arthritogenic, in HLA–DR4–transgenic mice: Comment on the article by Kinloch et al

“…Using the same immunization protocol, we further assessed the arthritogenicity of human ␣-enolase/citrullinated human ␣-enolase in HLA-DR4-transgenic mice on the same B10 Ncf1*/* background (B10.DR4 Ncf1*/* ) (6). We observed antibody reactivity toward human ␣-enolase and citrullinated human ␣-enolase in all 3 strains and, as described by Kinloch et al (2), the reactivity occurred in a citrulline-independent manner. However, in contrast to their results, our mice remained healthy throughout the experiments, which were terminated 130 or 132 days after immunization.…”

“…In a recent report in Arthritis & Rheumatism, Kinloch et al (2) describe rapid onset of arthritis in DR4-IE-transgenic mice induced by human or Porphyromonas gingivalis citrullinated and native ␣-enolase. Wild-type (WT) and class II major histocompatibility complex-deficient C57BL/6 mice did not develop arthritis upon immunization with human ␣-enolase or citrullinated human ␣-enolase.…”

Mechanisms of Immunological Tolerance Disruption

“…Тре-тья группа связывается перекрестной связью с двумя цепями MHC II класса (энтеротоксин A S. aureus) [Fraser, Proft, 2008]. Эти данные по суперантигенам представляют интерес в связи с тем, что бактериальные или вирусные инфек-ции обнаруживаются у большинства больных АИЗ, в частности РА: P. gingivalis [Martinez-Mar-Martinez-Mar--Mar-Martinez et al, Röhner et al, 2010], EBV [Klatt et al, 2005;Erre et al, 2015], CMV [Pierer et al, 2012;Mohammad et al, 2014]. В ряде работ было показано, что иммунизация с P. gingiva-.…”

“…В ряде работ было показано, что иммунизация с P. gingiva-. gingivagingivalis или энолазой P. gingivalis индуцировала или усугубляла артрит [Cantley et al, 2011;Kinloch et al, 2011].…”

“…В ранних ис-следованиях было показано, что EBV может способствовать поликлональной В-клеточ-ной активации у больных РА [Klatt et al, 2005], клональной экспансии EBNA-1 специфических Т-клеток, которые распознают антигены мие-лина у больных РС [Lunemann et al, 2008]. Ряд исследований свидетельствуют о иммунопато-генной связи вирионов HERV-W с РС, поскольку белок его оболочки (ENV) может способство-вать не только массовой неспецифической ак-тивации Т-лимфоцитов Antony et al, 2011], но также вызывать спонтанную ак-тивацию врожденного иммунитета через Tolllike Receptor-4 (TLR4) и CD14 .…”