Diphenylamine ; Humans ; Poisoning/diagnosis* ; Tablets

BACKGROUND: APRIL, originally known as a cytokine involved in B cell survival, is now known to regulate the inflammatory activation of macrophages. Although the signal initiated from APRIL has been demonstrated, its role in cellular activation is still not clear due to the presence of BAFF, a closely related member of TNF superfamily, which share same receptors (TACI and BCMA) with APRIL. METHODS: Through transfection of siRNA, BAFF-deficient THP-1 cells (human macrophage-like cells) were generated and APRIL-mediated inflammatory activities were tested. The expression patterns of APRIL were also tested in vivo. RESULTS: BAFF-deficient THP-1 cells responded to APRIL-stimulating agents such as monoclonal antibody against APRIL and soluble form of TACI or BCMA. Furthermore, co-incubation of the siBAFF-deficient THP-1 cells with a human B cell line (Ramos) resulted in an activation of THP-1 cells which was dependent on interactions between APRIL and TACI/BCMA. Immunohistochemical analysis of human pathologic samples detected the expression of both APRIL and TACI in macrophage-rich areas. Additionally, human macrophage primary culture expressed APRIL on the cell surface. CONCLUSION: These observations indicate that APRIL, which is expressed on macrophages in pathologic tissues with chronic inflammation, may mediate activation signals through its interaction with its counterparts via cell-to-cell interaction.
Cell Communication ; Cell Line ; Cell Survival ; Diphenylamine ; Humans ; Inflammation ; Macrophages ; RNA, Small Interfering ; Transfection

OBJECTIVETo investigate the effect of inhibition and activation of MAPK-ERK1/2 pathway on the expression of osteogenic genes and proliferation of rat osteoblasts in vitro.

METHODSPrimarily cultured rat osteoblasts, identified by cell morphology studies and ALP staining, were exposed to 1% or 5% rat serum for 24 h or to the specific MAPK-ERK1/2 inhibitor PD0325901. The downstream molecules of MAPK-ERK1/2 pathway including p-ERK1/2 and ERK1/2, osteogenic genes such as Runx2 and Type I collagen, and proliferating cell nuclear antigen (PCNA) were detected by Western Blotting, and alkaline phosphatase activities were analyzed quantitatively.

RESULTSCompared with 1% rat serum-treated cells, exposure of the cells to a higher concentration (5%) of rat serum caused a significantly increased phosphorylation level of p-ERK1/2 (P<0.05) and obviously enhanced expressions of the osteogenic genes (Runx2, type I collagen and ALP) and PCNA (P<0.05). Inhibition of the MAPK-ERK1/2 pathway with PD0325901 resulted in suppressed expressions of the osteogenic genes and PCNA.

CONCLUSIONThe activation of MAPK-ERK1/2 pathway promotes the expression of osteogenic genes such as Runx2, type I collagen and ALP and enhances the proliferative activity of the osteoblasts, while inhibition of this pathway suppresses the expressions of these genes and the cell proliferation, suggesting that this pathway may potentially serve as a therapeutic target for osteoporosis.

Alkaline Phosphatase ; metabolism ; Animals ; Antineoplastic Agents ; pharmacology ; Benzamides ; pharmacology ; Cell Proliferation ; drug effects ; Cells, Cultured ; Collagen Type I ; metabolism ; Core Binding Factor Alpha 1 Subunit ; metabolism ; Diphenylamine ; analogs & derivatives ; pharmacology ; Female ; Gene Expression Regulation ; drug effects ; MAP Kinase Signaling System ; drug effects ; Male ; Mitogen-Activated Protein Kinase 1 ; metabolism ; Mitogen-Activated Protein Kinase 3 ; metabolism ; Osteoblasts ; cytology ; metabolism ; Phosphorylation ; drug effects ; Proliferating Cell Nuclear Antigen ; metabolism ; Rats ; Rats, Sprague-Dawley