Fig. 2

Deficiency of Axl or Mertk enhances antibody-induced arthritis, but Tyro3 deficiency has an inhibitory effect. Arthritis in the knockout mice lacking Tyro3, Axl or Mertk and their littermate control was induced by K/BxN serum injection. On day 12 the mice were euthanized, and the hind ankle joints were removed. Joints were fixed in 4% paraformaldehyde and decalcified. Paraffin-embedded sections were stained with hematoxylin and eosin (H&E) and Safranin O and photographed under a microscope. Representative histologic images of the staining with H&E staining and Safranin O staining are shown(A-C). Histological score for bone erosion, cartilage erosion and synovitis between Tyro3-, Axl-, or Mertk-knockout mice and their littermate controls was calculated and compared (D-E), n = 6. Mann Whitney U test. *, p < 0.05; **, p < 0.01. Ca, calcaneus; S, synovium; Ta, talus; Ti, tibia; M, bone marrow; C, cartilage