Figure 4.

Bifidobacterium longum RAPO alleviates RA in collagen-induced arthritis (CIA) mice. CIA mice (n = 5 per group) were orally administered B. longum RAPO (1 × 10⁸ CFU/mouse) or methotrexate (MTX; 3 mg/kg) once daily for 7 weeks after the immunization boost. (A) Reductions in arthritis score and arthritis incidence in CIA mice treated with B. longum RAPO. Effects of B. longum RAPO on RA development in CIA mice. (B) Tissue specimens were acquired from the hind paw joints of mice and stained with hematoxylin and eosin and safranin O. Representative histological quality and histological grades are shown. (C) Splenocytes isolated at 7 weeks after immunization were stimulated with phorbol myristate, ionomycin, and GolgiStop for 4 h. The percentages of Th1 (CD4⁺IFN-γ⁺), Th2 (CD4⁺IL-4⁺), and Th17 (CD4⁺IL-17⁺) cells were analyzed using flow cytometry, including also Treg (CD4⁺CD25^high Foxp3⁺). (D) Levels of IgA, IgM, IgG2a, and anti-CII-specific IgG2a antibodies in the serum of CIA mice at 7 weeks after the first immunization. Data are presented as the means ± SDs. *p < 0.05; **p < 0.01; ***p < 0.001 (vs. vehicle-treated group).