Exacerbation of Aging-Associated and Instability-Induced Murine Osteoarthritis With Deletion of D Prostanoid Receptor 1, a Prostaglandin D 2 Receptor.

OBJECTIVE: D prostanoid receptor 1 (DP1), a receptor for prostaglandin D2 , plays important roles in inflammation and cartilage metabolism. However, its role in the pathogenesis of osteoarthritis (OA) remains unknown. This study was undertaken to explore the roles of DP1 in the development of OA in murine models and to evaluate the efficacy of a DP1 selective agonist in the treatment of OA.

METHODS: The development of aging-associated OA and destabilization of the medial meniscus (DMM)-induced OA was compared between DP1-deficient (DP1-/- ) and wild-type (WT) mice. The progression of OA was assessed by histology, immunohistochemistry, and micro-computed tomography. Cartilage explants from DP1-/- and WT mice were treated with interleukin-1α (IL-1α) ex vivo, to evaluate proteoglycan degradation. The effect of intraperitoneal administration of the DP1 selective agonist BW245C on OA progression was evaluated in WT mice.

RESULTS: Compared to WT mice, DP1-/- mice had exacerbated cartilage degradation in both models of OA, and this was associated with increased expression of matrix metalloproteinase 13 and ADAMTS-5. In addition, DP1-/- mice demonstrated enhanced subchondral bone changes. Cartilage explants from DP1-/- mice showed enhanced proteoglycan degradation following treatment with IL-1α. Intraperitoneal injection of BW245C attenuated the severity of DMM-induced cartilage degradation and bony changes in WT mice.

CONCLUSION: These findings indicate a critical role for DP1 signaling in OA pathogenesis. Modulation of the functions of DP1 may constitute a potential therapeutic target for the development of novel OA treatments.