Fig. 5: Kaempferol inhibits RA development in the collage-induced arthritis mouse model.

a, b Inhibitory effects of kaempferol on Th17 lineage differentiation and inflammatory cytokine production were analyzed using mouse splenocytes. The inhibitory effects of kaempferol on Th17-polarized T-cell differentiation (a), secretion of IL-17 (b, left graph), IL-21 (b, middle graph), and TNF-α (b, right graph) were determined by counting IL-17⁺/CD4⁺-expressing T-cell cells using flow cytometry (a) and sandwich ELISA (b), respectively. Data were obtained from three independent experiments, and values are represented as means ± SEM. *p < 0.05; **p < 0.01; ***p < 0.001 vs. untreated cells. c Kaempferol effects on RA development in CIA mice were analyzed as described in the Materials and Methods. RA incidence (top graph) and clinical arthritis severity (bottom graph) were obtained from CIA + vehicle control group (n = 10) and CIA + kaempferol group (n = 10). Values are represented as means ± SD. Each point of the CIA + kaempferol groups was compared with the corresponding CIA + vehicle control group. *p < 0.05. d Representative photographs of the effects of kaempferol on RA development in CIA mice. Tissue specimens obtained from the hind paw joints of each group of mice (each n = 5) (c) at the end point of the experiment were analyzed by staining with H&E, safranin O, and TRAP, respectively. Inflammation, cartilage, bone damage, and TRAP⁺ osteoclasts were quantified as described in the Materials and Methods. Data were obtained from each group (CIA + vehicle, n = 5; CIA + kaempferol, n = 5), and values are represented as means ± SEM. **p < 0.001. e Inhibitory effects of kaempferol on the mRNA expression of genes involved in Th17 differentiation by real-time PCR using draining lymph node cells of CIA + vehicle and CIA + kaempferol mice, as indicated. f Inhibitory effects of kaempferol on the activated signaling proteins involved in the differentiation of Th17 cells were measured by immunohistofluorescence assay using the spleens of CIA + vehicle and CIA + kaempferol mice, as indicated. The spleen tissue specimens were co-stained as indicated, and the positive cells were counted using randomly photographed confocal images obtained from three different areas. e, f Data were obtained from each mouse group (CIA + vehicle, n = 3; CIA + kaempferol, n = 3), and values are represented as means ± SEM. *p < 0.05; **p < 0.01; ***p < 0.001