Vascular endothelial growth factor A, angiopoietin 1 and angiopoietin 2 show different temporal patterns of expression during the course of collagen-induced arthritis. Collagen-induced arthritis (CIA) was induced, and joint extracts were isolated from normal DBA1 mice and from early (day 26), active (day 38) and chronic (day 52) CIA mice (n = 4 for each group). (A) Representative sections of the ankle joints stained with hematoxylin and eosin (bars = 500 μm) from normal DBA1 and early, active and chronic CIA mice. (B) Sequential changes in the expression levels of angiopoietin 1 (Ang1) and Ang2 proteins in the joint tissue were determined by Western blot analysis. (C) The vascular endothelial growth factor A (VEGF-A) concentration in the joint tissue was determined by enzyme-linked immunosorbent assays. Values are mean ± SE. *P < 0.05 vs. normal.
Hah et al. Arthritis Research & Therapy 2013 15:R85 doi:10.1186/ar4265