No abstract

Recovery of bone loss is one of the active research issues in bone medicine due to the need for efficient measures for bone gain. We examined here a novel drug delivery system using a nanogel of cholesterol-bearing pullulan (CHP) in combination with prostaglandin E2 (PGE2). PGE2 or PGE2/CHP, vehicle (saline containing 0.06% ethanol and 0.02% Tween 80) or CHP were injected on to the calvariae of mice once every day for 5 days per week for 4 weeks. Low dosage of PGE2 (0.6 microg) alone or CHP alone did not induce new bone formation in this system. In contrast, PGE2 (0.6 microg)/CHP induced new bone formation. Bone formation activities of PGE2 was enhanced by CHP nanogels only at the site of injection (calvaria) but not in the distant sites of the skeleton, showing that PGE2/CHP could avoid systemic effects. In spite of the fact that previously reported animal models of bone formation by PGE2 were associated with loss of body weight, bone formation based on PGE2/CHP did not associate with loss of body weight. Furthermore, only a single application of PGE2 in combination with nanogel cross-linking hydrogel sphere (PGE2/CHP-PEO) induced new bone formation. Thus, nanogel-based delivery system is an efficient delivery system of bone anabolic agent, PGE2.

Objective. To investigate the molecular mechanisms underlying particle-induced osteolysis, we focused on osteopontin (OPN), a cytokine and cellattachment protein that is associated with macrophage chemoattractant and osteoclast activation.Methods. We compared OPN protein levels in human periprosthetic osteolysis tissues with those in osteoarthritis (OA) synovial tissues. To investigate the functions of OPN during particle-induced osteolysis in vivo, titanium particles were implanted onto the calvaria of OPN-deficient mice and their wild-type (WT) littermates. Mice were killed on day 10 and evaluated immunohistologically. The effects of OPN deficiency on the secretion of inflammatory cytokines were examined using cultured bone marrow-derived macrophages (BMMs). BMMs from OPN-deficient and WT mice were cultured with titanium particles for 12 hours, and the concentrations of inflammatory cytokines in the conditioned media were measured by enzyme-linked immunosorbent assay.Results. Expression of OPN protein was enhanced in human periprosthetic osteolysis tissues as compared with OA synovial tissues. In the particle-induced model of osteolysis of the calvaria, bone resorption was significantly suppressed by OPN deficiency via inhibition of osteoclastogenesis, whereas an inflammatory reaction was observed regardless of the genotype. Results of immunostaining indicated that OPN protein was highly expressed in the membrane and bone surface at the area of bone resorption in WT mice. When BMMs were exposed to titanium particles, the concentration of proinflammatory cytokines, such as tumor necrosis factor ␣, interleukin-1␣ (IL-1␣), IL-1␤, and IL-6, as well as chemotactic factors, such as monocyte chemoattractant protein 1 and macrophage inflammatory protein 1␣, in the conditioned medium were significantly reduced by OPN deficiency. Whereas phagocytic activity of BMMs was not attenuated by OPN deficiency, phagocytosis-mediated NF-B activation was impaired in OPN-deficient BMMs. These data indicated that OPN was implicated in the development of particleinduced osteolysis via the orchestration of pro-/ antiinflammatory cytokines secreted from macrophages.Conclusion. OPN plays critical roles in wear debris-induced osteolysis, suggesting that OPN is a candidate therapeutic target for periprosthetic osteolysis.

In this study, we investigated the effect of the antitumor necrosis factor alpha (anti-TNF-alpha) antibody, infliximab, combined with methotrexate (MTX) and MTX alone on the serum levels of interleukin (IL)-23 and IL-17 in rheumatoid arthritis (RA) patients. Infliximab combined with MTX was administered to 26 patients with RA (infliximab group), and MTX alone was given to 20 patients with RA (MTX group). We evaluated clinical and laboratory parameters, including the Disease Activity Scores of 28 joints (DAS28) and serum levels of IL-23 and IL-17 at baseline and at 14 and 30 weeks after the initial treatment with these drugs. Single regression analysis was performed between the levels of serum IL-23 and other clinical and laboratory parameters at baseline before the initial treatment with infliximab or MTX. A significant reduction of DAS28 scores was observed in both the infliximab and the MTX group at 14 and 30 weeks after the initial treatment. A significant decrease in serum levels of IL-23 was observed in the infliximab group but not in the MTX group at 14 and 30 weeks after the initial treatment. Serum IL-17 levels did not show a significant change during the follow-up period. At baseline, before the initial treatment with infliximab or MTX, serum IL-23 levels showed a significant correlation with DAS28 and the number of swollen joints. This study indicated that the reduction of serum IL-23 levels in RA patients was a novel action of infliximab.

Tumor necrosis factor-alpha (TNF-alpha) has an essential role in the pathogenesis of rheumatoid arthritis (RA) and has been known to induce the production of several inflammatory molecules in vivo. To analyze in vivo the active mechanism of the TNF-alpha blocking agent, etanercept, the serum levels of the cytokine interleukin-15 (IL-15) and the chemokines growth-regulated protein-alpha (Gro-alpha), and interferon-gamma inducible protein-10 (IP-10) in RA patients were measured. Twenty-two patients with RA were administered etanercept once or twice a week for more than 6 months. The clinical and laboratory parameters were measured and serum levels of IL-15, Gro-alpha, and IP-10 were determined using enzyme-linked immunosorbent assay (ELISA) kits at the baseline and at 3 and 6 months after the initial treatment. Additionally, the production of IL-15 and IP-10 by cultured synovial cells stimulated with TNF-alpha from RA patients was determined by ELISA. A significant decrease in serum levels of IL-15 and IP-10 was observed at 3 and 6 months after initial treatment with etanercept, but not in those of Gro-alpha. TNF-alpha induced production of IP-10, but not IL-15 in cultured synovial cells from RA patients. This study demonstrated for the first time the reduction of IP-10 and IL-15 production in RA patients as active mechanisms of etanercept.