Up-Regulation of the Inflammatory Response by Ovariectomy in Collagen-Induced Arthritis. Effects of Tin Protoporphyrin IX

We have studied the influence of ovariectomy on the inflammatory response and bone metabolism on CIA as a model of postmenopausal arthritis as well as the effects of tin protoporphyrin IX (SnPP), a heme oxygenase inhibitor. Ovariectomy in non-arthritic mice produced increased serum PGD(2) levels and up-regulated the expression of COX-2, h-PGDS, l-PGDS, and HO-1 in the joints. In CIA, ovariectomy potentiated the inflammatory response with higher levels of serum IL-6 and MMP-3, local PGD(2) and MMP-3 as well as trabecular bone erosion. In OVX-CIA, SnPP decreased the serum levels of IL-6, MMP-3, and PGD(2); down-regulated TNF alpha, COX-2, hPGDS, PGD(2), PGE(2), and MMP-3 in joint tissues; and also decreased focal bone loss in the inflamed joint. Ovariectomy up-regulates inflammatory mediators in non-arthritic and in arthritic animals. In the OVX-CIA model, SnPP exerts anti-inflammatory effects which are not associated with the prevention of systemic bone loss.