Fig. 2.

Effects of exercise on tarsal bone histological parameters in proteoglycan-induced arthritis (PGIA) and healthy mice. a) Representative images of the inflammatory infiltrate and cartilage damage scores in the tarsal joints of PGIA mice. The 0 (normal) score was established in the control group (healthy control), where the bone, cartilage, and synovium did not show alterations. The arthritis scores 1 (mild), 2 (moderate) and 3 (severe) were based on the inflammatory changes (presence of inflammatory cells and synovial hyperplasia) and structural remodelling (cartilage damage and bone erosion). The images were acquired with a 10× amplification. b) Representative images of histological findings in the tarsal joints of the four study groups at the end of the exercise intervention using haematoxylin and eosin (H&E) and Safranin-O/Fast green staining to unveil the cartilage proteoglycan. The proteoglycan loss (PL) allowed the assessment of cartilage damage. The rectangle delimits the section of the tissue stained with Safranin-O/Fast green which is shown in the lower right corner of each image. c) Representative images of cartilage damage in the four study groups using the Safranin-O/Fast green staining to unveil the proteoglycan content and its loss. d) and e) Joint involvement was scored by the semi-quantitative scale to describe inflammatory infiltrate and cartilage damage in the tarsal joints (8 mice per group). One-way analysis of variance (ANOVA) with post hoc Tukey’s test was used to compare histological measurements between groups. *p < 0.050. †p < 0.010. BE, bone erosion; BO, bone; CA, cartilage; CD, cartilage damage; IC, inflammatory cells; PG, proteoglycan; SH, synovial hyperplasia; SY, synovium.