Dataset Information

The P. gingivalis Autocitrullinome Is Not a Target for ACPA in Early Rheumatoid Arthritis.

ABSTRACT: Rheumatoid arthritis (RA), a chronic inflammatory disease affecting primarily the joints, is frequently characterized by the presence of autoimmune anticitrullinated protein antibodies (ACPA) during preclinical stages of disease and accumulation of hypercitrullinated proteins in arthritic joints. A strong association has been reported between RA and periodontal disease, and Porphyromonas gingivalis, a known driver of periodontitis, has been proposed as the microbial link underlying this association. We recently demonstrated P. gingivalis-mediated gut barrier breakdown and exacerbation of joint inflammation during inflammatory arthritis. In the present study, we investigated another potential role for P. gingivalis in RA etiopathogenesis, based on the generation of ACPA through the activity of a unique P. gingivalis peptidylarginine deiminase (PPAD) produced by this bacterium, which is capable of protein citrullination. Using a novel P. gingivalis W50 PPAD mutant strain, incapable of protein citrullination, and serum from disease-modifying antirheumatic drug-naïve early arthritis patients, we assessed whether autocitrullinated proteins in the P. gingivalis proteome serve as cross-activation targets in the initiation of ACPA production. We found no evidence for patient antibody activity specific to autocitrullinated P. gingivalis proteins. Moreover, deletion of PPAD did not prevent P. gingivalis-mediated intestinal barrier breakdown and exacerbation of disease during inflammatory arthritis in a murine model. Together, these findings suggest that the enzymatic activity of PPAD is not a major virulence mechanism during early stages of inflammatory arthritis.

SUBMITTER: Munoz-Atienza E

PROVIDER: S-EPMC7088229 | biostudies-literature | 2020 Apr

REPOSITORIES: biostudies-literature

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The <i>P. gingivalis</i> Autocitrullinome Is Not a Target for ACPA in Early Rheumatoid Arthritis.

Muñoz-Atienza E E Flak M B MB Sirr J J Paramonov N A NA Aduse-Opoku J J Pitzalis C C Curtis M A MA

Journal of dental research 20200106 4

Rheumatoid arthritis (RA), a chronic inflammatory disease affecting primarily the joints, is frequently characterized by the presence of autoimmune anticitrullinated protein antibodies (ACPA) during preclinical stages of disease and accumulation of hypercitrullinated proteins in arthritic joints. A strong association has been reported between RA and periodontal disease, and <i>Porphyromonas gingivalis</i>, a known driver of periodontitis, has been proposed as the microbial link underlying this a ...[more]

PMID: 31905316

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Project description:BackgroundAutoantibody production is a hallmark of rheumatoid arthritis (RA). Anti-citrullinated protein antibodies (ACPA) are highly disease-specific, and their presence is associated with more severe disease and poor prognosis compared to ACPA-negative patients. However, the immune cell composition associated with antibody-positive/negative disease is incompletely defined. Mass cytometry (MC) is a high-dimensional technique offering new possibilities in the determination of the immune cell composition in rheumatic diseases. Here, we set up a broad phenotyping panel to study the immune cell profile of early untreated RA to investigate if specific immune cell subsets are associated with ACPA+ versus ACPA- RA.MethodsFreshly obtained PBMCs of early, untreated RA patients (8 ACPA+ and 7 ACPA-) were analysed using a 36-marker MC panel, including markers related to various immune lineages. Data were processed using Cytosplore for dimensional reduction (HSNE) and clustering. Groups were compared using Cytofast. A second validation cohort of cryopreserved PBMCs obtained from early RA patients (27 ACPA+ and 20 ACPA-) was used to confirm MC data by flow cytometry (FC). FC data were processed and analysed using both an unsupervised analysis pipeline and through manual gating.ResultsMC indicated no differences when comparing major immune lineages (i.e. monocytes, T and B cells), but highlighted two innate subsets: CD62L+ basophils (p = 0.33) and a subset of CD16- NK cells (p = 0.063). Although the NK cell subset did not replicate by FC, FC replication confirmed the difference in CD62L+ basophil frequency when comparing ACPA+ to ACPA- patients (mean 0.32% vs. 0.13%; p = 0.01).ConclusionsAlthough no differences in major lineages were found between early ACPA+ and ACPA- RA, this study identified the reduced presence of activated basophils in ACPA-negative disease as compared to ACPA-positive disease and thereby provides the first evidence for a connection between activated basophils and ACPA status.

Project description:Patients with rheumatoid arthritis (RA) can test either positive or negative for circulating anti-citrullinated protein antibodies (ACPA) and are thereby categorized as ACPA-positive (ACPA+) or ACPA-negative (ACPA-), respectively. In this study, we aimed to elucidate a broader range of serological autoantibodies that could further explain immunological differences between patients with ACPA+ RA and ACPA- RA. On serum collected from adult patients with ACPA+ RA (n = 32), ACPA- RA (n = 30), and matched healthy controls (n = 30), we used a highly multiplex autoantibody profiling assay to screen for over 1600 IgG autoantibodies that target full-length, correctly folded, native human proteins. We identified differences in serum autoantibodies between patients with ACPA+ RA and ACPA- RA compared with healthy controls. Specifically, we found 22 and 19 autoantibodies with significantly higher abundances in ACPA+ RA patients and ACPA- RA patients, respectively. Among these two sets of autoantibodies, only one autoantibody (anti-GTF2A2) was common in both comparisons; this provides further evidence of immunological differences between these two RA subgroups despite sharing similar symptoms. On the other hand, we identified 30 and 25 autoantibodies with lower abundances in ACPA+ RA and ACPA- RA, respectively, of which 8 autoantibodies were common in both comparisons; we report for the first time that the depletion of certain autoantibodies may be linked to this autoimmune disease. Functional enrichment analysis of the protein antigens targeted by these autoantibodies showed an over-representation of a range of essential biological processes, including programmed cell death, metabolism, and signal transduction. Lastly, we found that autoantibodies correlate with Clinical Disease Activity Index, but associate differently depending on patients' ACPA status. In all, we present candidate autoantibody biomarker signatures associated with ACPA status and disease activity in RA, providing a promising avenue for patient stratification and diagnostics.

Project description:ObjectiveTo examine the degree to which shared risk factors explain the relationship of periodontitis (PD) to rheumatoid arthritis (RA) and to determine the associations of PD and Porphyromonas gingivalis with pathologic and clinical features of RA.MethodsPatients with RA (n = 287) and patients with osteoarthritis as disease controls (n = 330) underwent a standardized periodontal examination. The HLA-DRB1 status of all participants was imputed using single-nucleotide polymorphisms from the extended major histocompatibility complex. Circulating anti-P gingivalis antibodies were measured using an enzyme-linked immunosorbent assay, and subgingival plaque was assessed for the presence of P gingivalis using polymerase chain reaction (PCR). Associations of PD with RA were examined using multivariable regression.ResultsPresence of PD was more common in patients with RA and patients with anti-citrullinated protein antibody (ACPA)-positive RA (n = 240; determined using the anti-cyclic citrullinated peptide 2 [anti-CCP-2] test) than in controls (35% and 37%, respectively, versus 26%; P = 0.022 and P = 0.006, respectively). There were no differences between RA patients and controls in the levels of anti-P gingivalis or the frequency of P gingivalis positivity by PCR. The anti-P gingivalis findings showed a weak, but statistically significant, association with the findings for both anti-CCP-2 (r = 0.14, P = 0.022) and rheumatoid factor (RF) (r = 0.19, P = 0.001). Presence of PD was associated with increased swollen joint counts (P = 0.004), greater disease activity according to the 28-joint Disease Activity Score using C-reactive protein level (P = 0.045), and higher total Sharp scores of radiographic damage (P = 0.015), as well as with the presence and levels of anti-CCP-2 (P = 0.011) and RF (P < 0.001). The expression levels of select ACPAs (including antibodies to citrullinated filaggrin) were higher in patients with subgingival P gingivalis and in those with higher levels of anti-P gingivalis antibodies, irrespective of smoking status. Associations of PD with established seropositive RA were independent of all covariates examined, including evidence of P gingivalis infection.ConclusionBoth PD and P gingivalis appear to shape the autoreactivity of RA. In addition, these results demonstrate an independent relationship between PD and established seropositive RA.

Dataset Information

The P. gingivalis Autocitrullinome Is Not a Target for ACPA in Early Rheumatoid Arthritis.

Publications

The <i>P. gingivalis</i> Autocitrullinome Is Not a Target for ACPA in Early Rheumatoid Arthritis.

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