G-CSF receptor targeting in inflammatory arthritis. Mus musculus

G-CSF is a hemopoietic growth factor that has a role in steady state granulopoiesis, as well as in mature neutrophil activation and function. We developed a neutralizing monoclonal antibody to the murine G-CSF receptor (G-CSFR), which antagonizes binding of murine G-CSF and inhibits G-CSFR signalling. Anti-G-CSFR rapidly halts the progression of established disease in collagen antibody-induced arthritis (CAbIA). Neutrophil accumulation in joints is inhibited, without rendering animals neutropenic, suggesting an effect on homing to inflammatory sites. Neutrophils in the blood and arthritic joints of anti-G-CSFR treated mice show alterations in cell adhesion receptors, while anti-G-CSFR suppresses local production of proinflammatory cytokines and chemokines known to drive tissue damage. Our aim in this study was to use differential gene expression analysis of joint and blood neutrophils to more thoroughly understand the effect of G-CSFR blockade on the inflammatory response following anti-G-CSFR therapy in CAbIA. Overall design: C57BL/6 mice with collagen antibody-induced arthritis were injected intra-peritoneally at day 5 with 50 μg anti-G-CSFR (n = 20 mice) or control mAb (n = 10 mice). At day 7, neutrophils (CD45+ CD11bhi Ly6G+) were sorted (BD FACSAria) from pooled digests of the knee tissues, or peripheral blood, and the RNA was extracted from 3 such experiments, giving a total of 12 samples.