Immunohistological analysis of synovium treated with abatacept in rheumatoid arthritis.

The aim of this study was to investigate the histological changes following the treatment with abatacept compared with methotrexate (MTX) by an immunohistological examination of synovial tissue for eleven different molecules to detect the expression patterns of cytokines. We histologically assessed the synovial tissues from 10 methotrexate (MTX)-treated RA patients as controls and 5 abatacept plus MTX-treated RA patients. The synovium samples from both group were assessed by hematoxylin and eosin (HE) staining and analyzed for their expression of tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), matrix metalloproteinase-3 (MMP-3), CD20, CD68, vascular endothelial growth factor (VEGF), CD4, CD8, CD28, CD80, and CD86 by an immunohistological examination. HE staining showed that there was a decrease in cell proliferation in the synovium of the RA patients who received abatacept compared with the controls. TNF-α, IL-6, and VEGF were not significantly different in either of the groups. On the other hand, MMP-3, CD68, CD4, CD8, CD20, CD80, and CD86 were significantly decreased in the abatacept group compared with the control (P < 0.05). Based on the histological analysis of the synovium, it appears that the efficacy of the treatment with abatacept may involve the inhibition of cell proliferation, with decreases in the expression of MMP-3, CD68, CD4, CD8, CD20, CD80, and CD86 in the synovium. These findings indicate inhibition of not only T cells but also B cells and macrophages, which likely plays a role in the efficacy of abatacept in RA patients.