Figure 2.

Oral celastrol treatment ameliorated the histopathological aspects of adjuvant-induced arthritis (AIA) rats and reduced synovial CD68+ macrophages. Celastrol significantly impaired inflammatory cell infiltration (A), was associated with a number of synovial lining layers similar to normal values (B), and reduced bone erosions (C), thus preserving the normal joint structure (D). The celastrol-treated AIA rats showed a significant reduction in synovial cell proliferation as assessed by the Ki67 marker (E) and in the number of synovial CD68-positive cells (F). Healthy N = 8, arthritic N = 17, celastrol 1 μg/g/day N = 5, celastrol 2.5 μg/g/day N = 5, celastrol 5 μg/g/day N = 5, and celastrol 7.5 μg/g/day N = 4. The data are expressed as median with interquartile range. The differences were considered as statistically significant for p < 0.05, according to Mann–Whitney tests for comparisons between healthy and arthritic groups and p < 0.0125 according to Mann–Whitney tests with Bonferroni correction for comparisons between arthritic and celastrol-treated groups. *p < 0.05 and p < 0.0125.