tacrolimus and Osteolysis

Particle-induced periprosthetic osteolysis is the major cause for orthopedic implant failure. This failure is mediated mainly by the action of osteoclasts, the principal cells responsible for bone resorption and osteolysis. Therapeutic interventions to alleviate osteolysis have been focused on understanding and targeting mechanisms of osteoclastogenesis. The nuclear transcription factor NFAT is an essential terminal differentiation factor of osteoclastogenesis. This transcription factor is known to cooperate with c-jun/AP-1 in mediating RANKL-induced osteoclastogenesis. We have previously determined that RANKL is an essential cytokine mediator of particle-induced osteoclastogenesis, and that PMMA particles activate JNK and c-jun/AP-1 in bone marrow macrophages (osteoclast precursors). In the current study, we investigated the effect of PMMA particles on the NFAT signaling pathway in osteoclast precursor cells. Our findings point out that PMMA particles stimulate nuclear translocation of NFAT2 in wild-type osteoclast precursors, which is associated with increased osteoclastogenesis. More importantly, induction of osteoclastogenesis was selectively blocked in a dose-dependent fashion by the calcineurin inhibitors, Cyclosporine-A and FK506. Further, this activation was also blocked in a time-dependent fashion by the NFAT inhibitor VIVIT. Finally, we provide novel evidence that PMMA particles induce binding of NFAT2 and AP-1 proteins. Thus, our findings demonstrate that activation of the NFAT pathway in conjunction with MAP kinases is essential for basal and PMMA-stimulated osteoclastogenesis.

Topics: Animals; Cell Differentiation; Cells, Cultured; Cyclosporine; DNA; Immunosuppressive Agents; Male; MAP Kinase Signaling System; Mice; Mice, Inbred C57BL; NF-kappa B; NFATC Transcription Factors; Oligopeptides; Osteoclasts; Osteolysis; Polymethyl Methacrylate; Proto-Oncogene Proteins c-fos; Proto-Oncogene Proteins c-jun; RANK Ligand; Signal Transduction; Tacrolimus

Anti-arthritic effect of FTY720, a novel immunosuppressant, was compared with those of immunosuppressants cyclosporin A and tacrolimus in adjuvant-induced arthritis in rats.. Male LEW rats.. FTY720 (0.03-0.3 mg/kg), cyclosporin A (1-10 mg/kg) or tacrolimus (0.3-3 mg/kg) were orally administered to rats for 21 days beginning on the day (day 0) of adjuvant inoculation. In addition, the anti-arthritic effect of FTY720 (0.3 mg/kg) and cyclosporin A (10 mg/kg) were evaluated by administration to animals for 5 consecutive days (days 2-6, 6-10, and 10-14).. Adjuvant-induced arthritis was produced by intradermal injection of 0.5 mg heat-killed Mycobacterium tuberculosis. Hindpaw edema was measured plethysmographically. The day of arthritis onset was determined macroscopically. Bone degradation was determined by radiography. Peripheral blood leukocytes were classified microscopically.. All test compounds inhibited the incidence of arthritis, hindpaw edema and bone destruction. In addition, FTY720 but not cyclosporin A or tacrolimus markedly decreased the number of peripheral blood lymphocytes. FTY720 treatment on days 6 to 10 inhibited the bone destruction and hindpaw edema.. These results suggest that the anti-arthritic effect of FTY720 in this adjuvant-induced arthritic model was more potent than those of cyclosporin A and tacrolimus. FTY720 administered on days 6 to 10 showed the inhibitory effect on the bone destruction and hindpaw edema. FTY720 may be effective in the treatment of rheumatoid arthritis.

Topics: Animals; Arthritis, Experimental; Cyclosporine; Edema; Fingolimod Hydrochloride; Immunosuppressive Agents; Leukocyte Count; Lymphocytes; Male; Monocytes; Mycobacterium tuberculosis; Neutrophils; Osteolysis; Propylene Glycols; Rats; Rats, Inbred Lew; Sphingosine; Tacrolimus