The role of p105 protein in NFκB activation in ANA‐1 murine macrophages following stimulation with titanium particles

Abstract

Macrophage activation by particulate debris from orthopaedic implants triggers an inflammatory response that ultimately leads to periprosthetic bone resorption and implant failure. TNFa has been identified as a critical cytokine involved in the response to debris particles but the mechanisms involved in activation of TNFx synthesis are unclear. The current study demonstrates rapid induction of T N F r following stimulation with titanium particles in the murine macrophage cell line, ANA-1, Electrophoretic mobility shift assays demonstrated NFtiB DNA binding activity within 15 min of exposure to titanium particles, and experiments with an N FtiB luciferase promoter confirmed the induction of NFKB mediated transcription by titanium particles. Furthermore, titanium particles induced a ?-fold induction in T N F a promoter activity, and mutation of the tiB2a site, one of the four NFtiBbinding sites in the TNFx promoter, resulted in decreased activation. Since NFtiB is a critical regulator of inflammation and is involved in activation of the TNF? promoter, additional experiments were performed to determine the mechanism of N FtiB activation by particles. NFKB activation was found to be dependent upon proteasome activity, since administration of MG 132, a proteasome inhibitor, blocked NFtiB activation. However, ItiBa is only slightly decreased following Ti treatment, in contrast to marked degradation following stimulation with LPS. Recently, another proteasome-dependent pathway of NFtiB activation has been described involving degradation of p105, a precursor of p50 that binds to p65. p105 degradation occurred following titanium stimulation. suggesting that this recently described mechanism for NFtiB activation is operant in ANA-1 cells following exposure to titanium particles. These findings demonstrate that activation of the NFtiB signaling pathway is rapidly induced by titanium particles in ANA-1 cells and is associated with p105 degradation. TNF'r induction appears to be mediated, at least in part, through NFtiB binding to the ~B 3 a site of the TNFx promoter. 8

NF‐kB signaling blockade abolishes implant particle‐induced osteoclastogenesis

“…They showed that titanium particles activate mitogen-activated protein kinase, and pharmacological inhibition of tyrosine and serinekhreonine kinaseactivity inhibited particle-induced NF-kB activation. Soloviev et al [32] have investigated titanium particle-induced NF-kB activation in ANA-I murine macrophages. In these cells particles activate NF-kB and the activated NF-kB complexes contain the p50, p65 and c-re1 subunits.…”

Aseptic loosening, not only a question of wear: A review of different theories

“…NF-κB is sequestered in the cytoplasm by an inhibitor κBα (IκBα), which binds to NF-κB and prevents its translocation to the nucleus (Chen and Ghosh 1999). TNF-α induction seems to be affected in some part of NF-κB binding to the kB2 site of the TNF-α promotor (Soloviev et al 2002). An important issue in order to find therapeutic strategies is to determine the cellular response to wear particles with different properties.…”

“…NF-κB has been shown to be required for osteoclast development (Franzoso et al 1997). Lipopolysaccharide (LPS) appears to activate pathways other than the ones activated by particles: both agonists cause NF-κB activation, but LPS has an inhibitory effect on IκB (Soloviev et al 2002).…”

How Has the Introduction of New Bearing Surfaces Altered the Biological Reactions to Byproducts of Wear and Modularity?

“…Studies have also shown a variety of cell signaling pathways are involved in the cellular response to debris. These include mitogenactivated protein kinase activation [1], induction of granulocyte macrophage colony-stimulating factor [6], C-C chemokine expression [55], matrix metalloproteinase induction [56], NFkB activation [59,66,72], nitric oxide elicitation [45,64,75], induction of apoptosis [74], cytokine activation [43,78], and direct activation of cyclooxygenase-2 [82]. Although most studies on the etiology of aseptic loosening have been focused on macrophage as the central cell of interest, there is recent interest in examining the role of the fibroblasts in the MMPs 56 UHMWPE = ultrahigh-molecular-weight polyethylene; IL = interleukin; TNF = tumor necrosis factor; GM-CSF = granulocyte macrophage colony-stimulating factor; MMPs = matrix metalloproteinases.…”