Arthritis Evaluation in CD11c-Flip-KO Mice

CD11c-Flip-KO and the littermates were assessed for the spontaneous development of arthritis on a weekly basis from 4 weeks to 36 weeks of age. The clinical severity score was defined as the sum (maximum=28) of joint swelling/inflammation (0–3 each of 4 paws/ankles), joint deformity (including toe flexion, contraction and shortening, 0–3 of each of 4 paws/ankles) and the grip strength (on a 3 mm diameter of wires, 0–4/mouse)^{57 (link)}. The clinical incidence was defined as any mouse with clinically observed joint swelling/inflammation ≥ 1. The histologic analysis was performed utilizing paraffin embedded sections of interphalangeal joints of the back and front paws, ankles, and knees subjected to hematoxylin and eosin (H&E) staining⁵⁸ . H&E ankle sections were evaluated by a blinded pathologist for inflammation (0–5), bone erosion (0–5), pannus formation (0–5) and median synovial lining thickness, neutrophil infiltration, and cartilage destruction^{58 , 59 (link)}. Macrophages in ankles were identified by immunohistochemistry staining by the Northwestern University Mouse Histology & Phenotyping Laboratory employing anti-F4/80 (eBioscience, cat. no. 14-4801, 1:1000) or isotype matched control IgG (eBioscience, cat. no. 16-4321) antibodies.