Affinity purified anti-citrullinated protein/peptide antibodies target antigens expressed in the rheumatoid joint

Ossipova, Elena; Cerqueira, Cátia; Reed, Evan; Kharlamova, Nastya; Israelsson, Lena; Holmdahl, Rikard; Nandakumar, Kutty Selva; Engström, Marianne; Harre, Ulrike; Schett, Georg; Catrina, Anca I.; Malmström, Vivianne; Sommarin, Yngve; Klareskog, Lars; Jakobsson, Per‐Johan; Lundberg, Karin

doi:10.1186/ar4683

Cited by 41 publications

(60 citation statements)

References 35 publications

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“…Prior studies in patients with established RA have revealed multiple clonal families of antibodies, many of which bind to known RA-related autoantigens. Thus, this method is capable of isolating 2378 KINSLOW ET AL monoclonal autoantibodies and identifying their cognate antigens (23,(40)(41)(42)(43). Similar approaches can be used in preclinical RA to identify plasmablast abnormalities with relevance to the pathogenesis of RA.…”

Section: Discussionmentioning

confidence: 99%

Elevated IgA Plasmablast Levels in Subjects at Risk of Developing Rheumatoid Arthritis

Kinslow

Blum

Deane

et al. 2016

Arthritis & Rheumatology

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Objective The disease process in rheumatoid arthritis (RA) starts years before clinical diagnosis, and elevated disease-specific autoantibodies can be detected in this period. Early responses to known or novel autoantigens likely drive the eventual production of pathogenic autoimmunity. Importantly, the presence of disease-specific autoantibodies can identify individuals who are at high-risk for future RA onset but are currently without arthritis. The goal of the current studies is to characterize plasmablasts in these individuals. Methods We investigated the antibody-secreting plasmablasts of a well characterized cohort of individuals at-risk for RA based on serum RA-related autoantibody positivity (Ab+) in comparison to patients with early (<1 yr) seropositive RA and healthy controls. The plasmablast antibody repertoires of at-risk subjects were analyzed using DNA barcode-based methods with paired heavy- and light-chain gene sequencing. Cells were single-cell sorted prior to sequentially adding cell- and plate-specific DNA barcodes, followed by next-generation sequencing. Results Total plasmablast levels were similar in Ab+ individuals (1%) and controls (0.4–1.6%). However, increased frequencies of IgA+ vs. IgG+ plasmablasts were observed in Ab+ individuals (39% IgA+, 37% IgG+ plasmablasts) as compared to other groups (1–9% IgA+, 71–87% IgG+ plasmablasts). Paired antibody sequences from Ab+ subjects revealed cross-isotype clonal families and similar sequence characteristics between the IgA and IgG plasmablast repertoires. Ab+ individuals also demonstrated elevated serum levels of IgA isotype anti-CCP3 antibodies. Conclusion The IgA plasmablast dominance in these Ab+ individuals suggests that a subset of RA-related autoantibodies may arise from mucosal immune responses and be involved in early disease pathogenesis in individuals who are at-risk for developing RA.

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Section: Discussionmentioning

confidence: 99%

Elevated IgA Plasmablast Levels in Subjects at Risk of Developing Rheumatoid Arthritis

Kinslow

Blum

Deane

et al. 2016

Arthritis & Rheumatology

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“…For example, fibrinogen (subunits α, β, γ) was identified in 16% of ACPA positive synovial immune complexes, but also in 44% of ACPA negative immune complexes isolated using protein-G (data not shown), suggesting that this protein may associate with ACPA both specifically as a citrullinated autoantigen, and as a non-antigen bound protein. There is now considerable evidence incriminating fibrinogen as a specific target for ACPA in RA, and it is widely detectable in the synovial microenvironment [15, 32, 33]. Other well characterized candidate autoantigens include vimentin, α-enolase, and collagen type II [5, 6, 10, 15, 32, 34].…”

Section: Discussionmentioning

confidence: 99%

“…There is now considerable evidence incriminating fibrinogen as a specific target for ACPA in RA, and it is widely detectable in the synovial microenvironment [15, 32, 33]. Other well characterized candidate autoantigens include vimentin, α-enolase, and collagen type II [5, 6, 10, 15, 32, 34]. Surprisingly, we identified vimentin in only 1/19 ACPA positive immune complexes from RA synovial fluids, and we did not identify α-enolase or collagen type II in any of the synovial immune complexes, whether they were isolated using protein-G or CCP3.…”

Section: Discussionmentioning

confidence: 99%

Characterization of Autoantigens Targeted by Anti-Citrullinated Protein Antibodies In Vivo: Prominent Role for Epitopes Derived from Histone 4 Proteins

Meng¹,

Ezzati²,

Smolik³

et al. 2016

PLoS ONE

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Anti-citrullinated protein antibodies (ACPA) have become an integral part of the clinical definition of rheumatoid arthritis, and are hypothesized to be important in the immunopathogenesis of this autoimmune disease. Several citrullinated proteins have been demonstrated to serve as candidate autoantigens for the ACPA, based on in vitro immune reactions between citrullinated peptides/proteins and RA sera. Yet it remains unclear whether the autoantigens identified in vitro are indeed directly and specifically targeted by the ACPA in vivo. Moreover, it is unclear whether ACPA present in RA sera are directed towards the same spectrum of autoantigens as the ACPA present within the synovial compartment. In this study, we isolated ACPA immune complexes from RA synovial fluids (SF) and sera by using immobilized cyclic citrullinated peptides (CCP3) based immune affinity, and characterized the proteins that are directly and specifically associated with them by mass spectrometry. The results demonstrate that four histone proteins are prominent ACPA autoantigens, with the frequency of detection being histone H4 (89%), H2B (63%), H3 (63%), and H2A (58%) in ACPA positive RA SF. We further demonstrate that a histone 4 peptide containing citrulline at position Cit39 was recognized by 100% of ACPA positive RA SF. An adjacent citrulline residue at Cit40 was recognized by 34% of ACPA positive RA SF. An H4 peptide containing Cit39-40 was recognized in the serum of 94% ACPA positive RA, 77% ACPA positive first-degree relatives (FDR) of RA patients, and 2.5% of healthy controls. The Cit39-40 peptide substantially blocked the ACPA reactivity in both SF and serum. Although the spectrum of ACPA we identified was limited to those isolated using immobilized CCP3 peptides, the findings indicate that H4 is a widely recognized RA autoantigen in both the synovial and serum compartments. The identification of this immunodominant ACPA epitope may be valuable in designing approaches to immune tolerance induction in RA.

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“…The presence of five or more ACPA antibody types and high levels of total IgG anti-CCP2 were associated with more severe disease progression [44]. In general IgM, IgA and the IgG subclasses all seem to contribute to ACPAmediated clinical symptoms, with the available data suggesting ACPA IgG being the most prominent disease inducer [44,50,51]. In agreement with this published literature, it was difficult to pinpoint a single isotype or IgGsubclass promoting the strongest cellular response, as all show underlying secondary correlations.…”

Section: Discussionmentioning

confidence: 99%

Label-free detection of immune complexes with myeloid cells

Szittner

Bentlage

Rovero

et al. 2016

Clinical and Experimental Immunology

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SummaryThe aim of this study was to provide proof-of-concept for quantitative and qualitative label-free detection of immune complexes through myeloid cells with imaging surface plasmon resonance. Surface plasmon resonance imaging was first applied to monitor the binding of human sera from healthy and rheumatoid arthritis (RA) patients to immobilized citrullinated RA-specific peptide antigens, histone citrullinated peptide 2 (HCP2) and viral citrullinated peptide 2 (VCP2). Next, the binding of monocytoid cell line U937 to the resulting immune complexes on the sensor surface was monitored. As control, binding of U937 was monitored to immunoglobulin (Ig)G subclasses simultaneously. Cell response results were compared to results of cyclic citrullinated peptide 2 (CCP2) enzyme-linked immunosorbent assay (ELISA), clinical RA diagnosis and antigen-specific antibody distribution of the samples. Human IgG3 triggered the most pronounced response, followed by IgG1 and IgG4, while IgG2 did not result in U937 cell binding. Serum samples obtained from RA patients resulted in a significantly increased cell response to VCP2 compared to healthy controls. The strength of cell response towards VCP2 immune complexes showed significant correlation with levels of antigen-specific IgA, IgG and IgG3. Cellular responses on VCP2 immune complexes showed significant association with both CCP2-based serological positivity and European League Against Rheumatism (EULAR) criteria-based clinical RA diagnosis. Immunoglobulin-triggered binding of monocytoid cells can be monitored using a label-free multiplex technology. Because these binding events are presumably initiated by Fc receptors, the system provides a tool for biological detection of autoantibodies with diagnostic value, here exemplified by anti-citrullinated antibodies. This provides added information to antibody levels, as interaction with Fc-receptor-expressing cells is also affected by post-translational modification of the immunoglobulins.

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Affinity purified anti-citrullinated protein/peptide antibodies target antigens expressed in the rheumatoid joint

Cited by 41 publications

References 35 publications

Elevated IgA Plasmablast Levels in Subjects at Risk of Developing Rheumatoid Arthritis

Elevated IgA Plasmablast Levels in Subjects at Risk of Developing Rheumatoid Arthritis

Characterization of Autoantigens Targeted by Anti-Citrullinated Protein Antibodies In Vivo: Prominent Role for Epitopes Derived from Histone 4 Proteins

Label-free detection of immune complexes with myeloid cells

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