Carbamylation of vimentin is inducible by smoking and represents an independent autoantigen in rheumatoid arthritis

Abstract

ObjectivesSmoking has been connected to citrullination of antigens and formation of anti-citrullinated peptide antibodies (ACPAs) in rheumatoid arthritis (RA). Since smoking can modify proteins by carbamylation (formation of homocitrulline), this study was conducted to investigate these effects on vimentin in animal models and RA.MethodsThe efficiency of enzymatic carbamylation of vimentin was characterised. B-cell response was investigated after immunisation of rabbits with different vimentin isoforms. Effects of tobacco smoke exposure on carbamylation of vimentin and formation of autoantibodies were analysed in mice. The antibody responses against isoforms of vimentin were characterised with respect to disease duration and smoking status of patients with RA.ResultsEnzymatic carbamylation of vimentin was efficiently achieved. Subsequent citrullination of vimentin was not disturbed by homocitrullination. Sera from rabbits immunised with carbamylated vimentin (carbVim), in addition to carbVim also recognised human IgG-Fc showing rheumatoid factor-like reactivity. Smoke-exposed mice contained detectable amounts of carbVim and developed a broad immune response against carbamylated antigens. Although the prevalence of anti-carbamylated antibodies in smokers and non-smokers was similar, the titres of carbamylated antibodies were significantly increased in sera of smoking compared with non-smoking RA. CarbVim antibodies were observed independently of ACPAs in early phases of disease and double-positive patients for anti-mutated citrullinated vimentin (MCV) and anti-carbVim antibodies showed an extended epitope recognition pattern towards MCV.ConclusionsCarbamylation of vimentin is inducible by cigarette smoke exposure. The polyclonal immune response against modified antigens in patients with RA is not exclusively citrulline-specific and carbamylation of antigens could be involved in the pathogenesis of disease.Trial registration number ISRCTN36745608; EudraCT Number: 2006-003146-41.

Periarticular Bone Loss in Arthritis Is Induced by Autoantibodies Against Citrullinated Vimentin

“…IgG was isolated by purification over a protein G column (GE Healthcare, Freiburg, Germany) according to the manufacturer's instructions and anti‐MCV antibodies were then purified by affinity column as described . The specificity of anti‐MCV was verified with a previously described ELISA (Orgentec) using unmodified, citrullinated, carbamylated, and acetylated versions of the vimentin epitope NH2‐GGVYATRSSAVR‐OH . In addition, reactivity against unmodified and citrullinated fibrinogen and enolase (Orgentec) were tested by ELISA and Western blotting.…”

Autoantibodies and B Cells: The ABC of rheumatoid arthritis pathophysiology

“…Interestingly, smoking has been found to be linked with other posttranslational modifications besides citrullination, potentially contributing to the development of AMPA. In particular, mice exposed to tobacco smoke show increased carbamylation of vimentin and develop higher titers of antibodies against it . Smoking can also be indirectly linked to acetylation, as smoking is thought to decrease the enzymatic activity of histone deacetylases via oxidative stress …”

“…In particular, mice exposed to tobacco smoke show increased carbamylation of vimentin and develop higher titers of antibodies against it. 153 Smoking can also be indirectly linked to acetylation, as smoking is thought to decrease the enzymatic activity of histone deacetylases via oxidative stress. 154 The link between microbiome and AMPA is furthermore intriguing, as secretory forms of ACPA, RF, and anti-CarP are specifically present in RA and consist predominantly of the IgM isotype.…”

Immune checkpoint inhibitor–induced inflammatory arthritis as a model of autoimmune arthritis

“…[90][91][92] A growing number of other anti-modified protein antibodies (AMPAs) have been identified in patients with RA, including those to carbamylated (anti-CarP) and acetylated antigens as well as malondialdehyde-acetaldehyde (MAA) adducts. 93,94 Formed as a result of the lipid peroxidation product malondialdehyde (MDA) chemically reacting with acetaldehyde and proteins, MAA adducts have been seen to co-localize with citrullinated proteins by confocal microscopy and are recognized by autoantibodies in 38% of ACPA-positive and 26% of ACPA-negative patients with RA. 95 Carbamylation, the conversion of lysine residues to homocitrulline through a reaction with cyanate, is also recognized by autoantibodies in a subset of patients with RA.…”