Fig. 1
SKG mice received an oral inoculation of Porphyromonas gingivalis (Pg) (108 colony-forming units per mouse) repeatedly every 3 days for 42 days after the laminarin (LA) immunization: control (Ctrl) n = 6, Pg n = 6, LA n = 6, Pg/LA n = 8. a Representative images of the palatal surfaces of the maxillary molars from the four groups (arrows indicate the resorption site). b Alveolar bone loss was analyzed by measuring the distance from the cemento-enamel junction to the alveolar bone crest on palatal surfaces. c Antibody titers to P. gingivalis in serum were measured by enzyme-linked immunosorbent assay. d Representative figures of hind paws for the four groups showing joint inflammation. e, f The severity and incidence of arthritis were scored by using Sakaguchi’s arthritis score. g Representative micro-computed tomography images of the talus. h, i Bone volume of the talus and percentage changes in bone volume relative to Ctrl mice. j, k Serum concentrations of interleukin-6 (IL-6) and matrix metalloproteinase-3 (MMP-3) in the four groups. l The correlation between the serum level of anti-citrullinated protein antibody (ACPA) in the Pg/LA group and anti-Pg antibody titer. Data represent the mean ± standard deviation (b, c, and d) or mean ± standard error of the mean (a, and e–k) of 6–8 mice per group. Statistical analyses were performed by using the Tukey-Kramer test, Bonferroni-corrected Mann–Whitney U test, or Pearson’s correlation coefficient (*P <0.05). Abbreviation: OD optical density