6 research outputs found
Molecular targeting of hepatocyte growth factor by an antagonist, NK4, in the treatment of rheumatoid arthritis
INTRODUCTION: Hepatocyte growth factor (HGF) is a potent proangiogenic molecule that induces neovascularization. The HGF antagonist, NK4, competitively antagonizes HGF binding to its receptor. In the present study, we determined the inhibitory effect of NK4 in a rheumatoid arthritis (RA) model using SKG mice. METHODS: Arthritis was induced in SKG mice by a single intraperitoneal injection of Ī²-glucan. Recombinant adenovirus containing NK4 cDNA (AdCMV.NK4) was also injected intravenously at the time of or 1 month after Ī²-glucan injection. Ankle bone destruction was examined radiographically. The histopathologic features of joints were examined using hematoxylin and eosin and immunohistochemical staining. Enzyme-linked immunosorbent assays were used to determine the serum levels of HGF, interferon Ī³ (IFN-Ī³, interleukin 4 (IL-4) and IL-17 production by CD4(+ )T cells stimulated with allogeneic spleen cells. RESULTS: The intravenous injection of AdCMV.NK4 into SKG mice suppressed the progression of Ī²-glucan-induced arthritis. Bone destruction was also inhibited by NK4 treatment. The histopathologic findings of the ankles revealed that angiogenesis, inflammatory cytokines and RANKL expression in synovial tissues were significantly inhibited by NK4 treatment. Recombinant NK4 (rNK4) proteins inhibited IFN-Ī³, IL-4 and IL-17 production by CD4(+ )T cells stimulated with allogeneic spleen cells. CONCLUSIONS: These results indicate that NK4 inhibits arthritis by inhibition of angiogenesis and inflammatory cytokine production by CD4(+ )T cells. Therefore, molecular targeting of angiogenic inducers by NK4 can potentially be used as a novel therapeutic approach for the treatment of RA
Blocking cāMet signaling enhances bone morphogenetic proteinā2āinduced osteoblast differentiation
We previously demonstrated that blocking hepatocyte growth factor (HGF) receptor/cāMet signaling inhibited arthritis and articular bone destruction in mouse models of rheumatoid arthritis (RA). In the present study, we investigated the role of cāMet signaling in osteoblast differentiation using the C2C12 myoblast cell line derived from murine satellite cells and the MC3T3āE1 murine preāosteoblast cell line. Osteoblast differentiation was induced by treatment with bone morphogenetic protein (BMP)ā2 or osteoblastāinducer reagent in the presence or absence of either HGF antagonist (NK4) or cāMet inhibitor (SU11274). Osteoblast differentiation was confirmed by Runx2 expression, and alkaline phosphatase (ALP) and osteocalcin production by the cells. Production of ALP, osteocalcin and HGF was verified by enzymeālinked immunosorbent assay. Runx2 expression was confirmed by reverse transcriptionāPCR analysis. The phosphorylation status of ERK1/2, AKT, and Smads was determined by Western blot analysis. Both NK4 and SU11274 enhanced Runx2 expression, and ALP and osteocalcin production but suppressed HGF production in BMPā2āstimulated C2C12 cells. SU11274 also enhanced ALP and osteocalcin production in osteoblastāinducer reagentāstimulated MC3T3āE1 cells. SU11274 inhibited ERK1/2 and AKT phosphorylation in HGFāstimulated C2C12 cells. This result suggested that ERK and AKT were functional downstream of the cāMet signaling pathway. However, both mitogenāactivated protein kinase/ERK kinase (MEK) and phosphatidylinositol 3ākinase (PI3K) inhibitor suppressed osteocalcin and HGF production in BMPā2āstimulated C2C12 cells. Furthermore, SU11274, MEK, and PI3K inhibitor suppressed Smad phosphorylation in BMPā2āstimulated C2C12 cells. These results indicate that although the cāMetāMEKāERKāSmad and cāMetāPI3KāAKTāSmad signaling pathways positively regulate osteoblast differentiation, cāMet signaling negatively regulates osteoblast differentiation, independent of the MEKāERKāSmad and PI3KāAKTāSmad pathways. Therefore, blocking cāMet signaling might serve as a therapeutic strategy for the repair of destructed bone in patients with RA