Histological/immunohistochemical analysis of Sema3A, NRP1, VEGF165 and CD3 in OA and RA synovial tissue. Representative HE staining of OA (A) and RA (D) synovial tissues. OA synovial tissues contain lining (LL) and sublining (SL) layers. RA synovial tissues are marked by the hyperplasia of synovial tissues in the lining layer and numerous infiltrated inflammatory cells (IC) in the sublining layer. Sema3A expression was detected in the lining layer and inflammatory cells in the sublining layer of OA (B) and RA (E) synovial tissues. The density of the Sema3A signal in the lining layer was lower in RA than OA. Peptide-neutralized anti-Sema3A antibodies did not stain tissue sections from OA (C) and RA (F). NRP1 and VEGF165 localized to the same areas as Sema3A in OA. VEGF165 expression in the lining layer in RA tissues was similar with OA (G, J). The NRP1 expression level in the lining layer of RA was similar to OA (H, K). T cells (CD3) and B cells (CD20) were detected among inflammatory cells in the sublining layer of OA and RA synovial tissues (I, L, M, N). The numbers of T cells and B cells were higher in RA synovial tissues compared with OA. Sections were counterstained with hematoxylin. Scale bars = 50 μm in the whole image view and 25 μm in the magnified view. Immunostaining of lining layer Sema3A was significantly decreased in RA (n = 12) synovial tissues compared with OA (n = 12) subjects (O). Results are presented as relative values compared with OA subjects. The box plots demonstrate the 10th and 90th percentile (whiskers), the 25th and 75th percentile, and the median. P values were obtained using the Mann–Whitney U-test.
Takagawa et al. BMC Musculoskeletal Disorders 2013 14:40 doi:10.1186/1471-2474-14-40