Background There is little evidence on prediction of clinical response to biologics in patients with RA. Recently, it has been suggested that clinical response to tumor necrosis factor (TNF) inhibitors was related to periodontal conditions, which might be affected by infection with Porphyromonas gingivalis (P.g.). Additionally, serum antibody responses to P. g were associated with RA and periodontitis.Newly established test of antibody against hemin binding protein 35 (HBP) of P.g., which has an ability specifically bind to P.g. containing protein HBP, can be available.
Objectives To evaluate whether serum antibody responses to P.g. antigens and periodontal conditions are associated with clinical response to biologics in patients with RA.
Methods 20 patients with severe RA enrolled in this study were treated with biologics according to the usual regimen. Clinical background and disease parameters were assessed at entry. DAS28-CRP was evaluated at 6 months (reassessment) after the initiation of biologics. Periodontal conditions were also assessed at entry. Serum levels of antibodies against P.g. sonicated extracts (SE) and HBP of P.g. were determined by enzyme-linked immunsorbent assay, respectively.
Results Their mean (SD) age was 57.2 (13.4) years. Patients were predominantly women (85%) with mean disease duration of 8.2 (6) years.10 patients were treated with TNF-i, 7 with IL-6 blocker and 3 with CTLA4-Ig, respectively. Most patients had active disease with DAS28-CRP 4.2 (0.9) at baseline, and showed an improvement of DAS28-CRP 2.87 (0.82) at reassessment. Seven patients (35%) achieved remission (DAS28-CRP <2.3) at reassessment. The mean serum levels of anti-CCP antibodies were 270.2 (221.9), and the mean serum levels of antibodies against P.g. SE and HBP were 15.9 (52.3) and 0.632 (0.276), respectively at baseline. Periodontal conditions of the patients were as follows; mean PD was 2.62 (0.51) (mm), mean CAL was 2.85 (0.77) (mm), mean PCR was 0.37 (0.23) (%), and mean BOP was 0.21 (0.17) (%) at baseline. No associations were observed between changes in DAS28-CRP (delta-DAS28-CRP) and serum and periodontal parameter values (serum levels of antibodies against P.g. SE and HBP, PD, CAL, PCR, and BOP). Antibody titers against P.g. SE gradually decreased, on the other hand, anti-P.g. HBP was increased during 6 months.
Conclusions Antibodies titers against P.g. and periodontal conditions could not predict the responses to biologics, but further studies are required to evaluate this hypothesis. And to our knowledge, this is the first report describing the change of serum level of antibodies against P.g. after treatments with biologics except infliximab.
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Disclosure of Interest None declared