The CO-releasing molecule CORM-3 protects against articular degradation in the K/BxN serum transfer arthritis model

Carbon monoxide-releasing molecules can counteract inflammatory responses. The aim of this study was to investigate whether tricarbonylchloro(glycinate)ruthenium (II) (CORM-3) is able to control the effector phase of experimental arthritis. Arthritis was induced in C57Black-6 mice by an intraperitoneal injection of serum from arthritic K/BxN mice. CORM-3 was administered intraperitoneally at 10 mg/kg/day (5 mg/kg twice a day) from days 0 to 10 and animals were sacrificed on day 11. Serum levels of osteocalcin and prostanoids were measured by enzyme-linked immunosorbent assay and radioimmunoassay. Gene expression was determined by real-time PCR. Histological analysis was performed and protein expression was examined by immunohistochemistry. Treatment with CORM-3 reduced the macroscopic score in hind paws, the migration of inflammatory cells and erosion of cartilage and bone. CORM-3 increased the levels of osteocalcin in the serum and reduced PGD2 levels, whereas PGE2 and 6-ketoPGF1alpha were not affected. In synovial tissues, we also observed a significant reduction in gene expression of interleukin-1beta, receptor activator of nuclear factor kappaB ligand (RANKL), matrix metalloproteinase (MMP)-9 and MMP-13. CORM-3 induced HO-1 expression in joint tissues but inhibited high mobility group box 1 (HMGB1), hematopoietic-prostaglandin D2 synthase (H-PGDS) and lipocalin-type prostaglandin D2 synthase (L-PGDS), as well as RANKL and intercellular adhesion molecule-1. COX-2 expression was not affected by CORM-3 treatment. We have shown that CORM-3 decreases the inflammatory response and protects against the degradation of cartilage and bone in the arthritic mice. Pharmacological CO delivery represents a novel strategy to regulate the effector phase of arthritis.