Fluorescence bioimaging analysis of collagen antibody-induced arthritis in male mice

The purpose of this study was to investigate the lesions of a mouse collagen antibody-induced arthritis (CAIA) model using fluorescence bioimaging and micro-computed tomography (micro-CT) and to compare it with histopathological examination. Twelve mice were randomly divided into three groups: group 1 (G1) as control, group 2 (G2) as fluorescence probe control and group 3 (G3) as collagen antibody-induced arthritis. The mice of G3 intravenously received anti-type II collagen 5-clone antibody cocktail (2 mg/mouse) on day 0 and intraperitoneally received lipopolysaccharide ($50{\mu}g/mouse$) on day 3. On the while, the mice of G1 and G2 received 0.9% saline in equal volumes at equivalent times. Fluorescence bioimaging and micro-CT analysis were carried out to assess arthritis. Treatment with the collagen antibody cocktail increased the paw thickness of mice compared to those in both the control and probe-treated groups. Fluorescence bioimaging using a near infrared imaging agent showed high intensity in the joints of collagen anti-body-treated mice, whereas those of control mice showed no signal. Micro-CT analysis of the knee joints of collagen antibody-treated mice showed rough and irregular articular appearance, whereas those of control mice showed normal appearance. Histopathological examination of the knee joints of collagen antibody-treated mice revealed destruction of cartilage and bony structure, synovial hyperplasia and infiltration of inflammatory cells. No cartilage destruction or inflammation was observed in control or probe control mice. Taken together, it is concluded that analyses of fluorescent bioimaging made it possible to evaluate CAIA lesions, comparable with those by micro-CT and histopathological examination in mice.