title: Mitogen-activated protein (MAP) kinases mediate PMMA-induction of osteoclasts.
abstract: Inflammatory osteolysis induced by implant-derived wear debris is associated with infiltration of various cell-types to the implant-bone interface leading to abundant secretion of pro-inflammatory cytokines and activation of proteinases that together lead to propagation of the localized inflammatory response and periprosthetic bone erosion. Tumor necrosis factor family members are considered to be direct mediators of inflammation and osteolysis. These cytokines exert their osteoclastic effects via activation of the transcription factor NF-kappaB and certain MAP kinases, including c-Jun, Erks and p38, all known to be essential for the development of osteoclasts. We have recently documented that the osteoclastogenic cytokines TNF and RANKL play a pivotal role in the development of inflammatory osteolysis. We have also found that PMMA particles stimulate osteoclastogenesis, at least in part, by induction of RANKL, TNF, and by activation of the transcription factor NF-kappaB. More importantly, our data indicate that inhibitors of the osteoclastogenic factors, TNF and RANKL abrogate particle-induced osteoclastogenesis. In the current study, we investigated if PMMA particles activate MAP kinases, and the potential role of these kinases as mediators of osteolysis. Using kinase assays, we show that in osteoclast precursors, PMMA particles markedly and rapidly activate p38 and ERK MAP kinases. This activation was specific, evident by complete blockade with specific inhibitory compounds. Similarly, we show that PMMA particles activate the JNK pathway, which is known to be involved in inflammatory and osteoclastogenic events. We also show that p38 MAP kinase regulates PMMA-activation of NF-kappaB, thus providing a possible mechanism for particle action in osteoclast precursors. Finally, we provide evidence that specific inhibitors of MAP kinases are capable of inhibiting PMMA-stimulated osteoclastogenesis. These data provide evidence that MAP kinases are potent mediators of particle-induced osteoclastogenesis.
authors.affiliation: Department of Orthopaedic Surgery, Washington University School of Medicine, St. Louis, MO 63110, USA.
authors.forename: S
authors.initials: S
authors.lastname: Abbas
authors.forename: J C
authors.initials: JC
authors.lastname: Clohisy
authors.forename: Y
authors.initials: Y
authors.lastname: Abu-Amer
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D004790:Enzyme Induction; D004791:Enzyme Inhibitors / Q000494:pharmacology; D048031:JNK Mitogen-Activated Protein Kinases; D048670:MAP Kinase Kinase 4; D008297:Male; D051379:Mice; D008809:Mice, Inbred C3H; D020929:Mitogen-Activated Protein Kinase Kinases / Q000037:antagonists & inhibitors / Q000096:biosynthesis; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000096:biosynthesis*; D016328:NF-kappa B / Q000096:biosynthesis; D010010:Osteoclasts / Q000187:drug effects* / Q000201:enzymology; D010014:Osteolysis / Q000139:chemically induced* / Q000473:pathology; D019904:Polymethyl Methacrylate / Q000494:pharmacology*; D048051:p38 Mitogen-Activated Protein Kinases
chemical_list: D004791:Enzyme Inhibitors; D016328:NF-kappa B; D019904:Polymethyl Methacrylate; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D048670:MAP Kinase Kinase 4; D020929:Mitogen-Activated Protein Kinase Kinases