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Expression of estrogen receptor related protein (p29) and estradiol binding in human arthritic synovium
T Ushiyama1, K Inoue, J Nishioka
1Department of Orthopaedic Surgery, Shiga University of Medical Science, Otsu, Japan.
Objective:
We investigated the expression of estrogen receptors (ER) and the presence of estradiol in human synovial tissues from subjects without arthritis and patients with traumatic arthritis, osteoarthritis, and rheumatoid arthritis.
Methods:
Synovial tissues were immunostained using ER-D5 monoclonal antibody (Mab) directed toward an ER related protein (p29), ER-ICA Mab directed toward nuclear ER, and antiestradiol serum. Fluorescent estradiol was used to demonstrate specific estradiol binding to ER.
Results:
(1) p29 was present predominantly in hyperplastic synovial lining cells and smooth muscles of blood vessels. (2) Exogenous estradiol bound to synoviocytes and sublining macrophage-like cells in the inflamed synovium. (3) Endogenous estradiol was also detected in hyperplastic lining cells and macrophage-like cells in arthritic synovium.
Conclusion:
Our study demonstrated the expression of ER in arthritic synovium and suggested that estrogen modulates local inflammation in various joint diseases via synoviocytes as well as sublining macrophage-like cells.