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Joint replacement is the most effective treatment for end-stage osteoarticular disease. However, macrophage-mediated aseptic loosening of joint prosthesis severely hampers the clinical effects of joint replacement. Until now, the mechanism by which macrophages regulate the secretion of inflammatory cytokines after particle stimulation is not clear. It is well known that the PI3 K/ AKT pathway participates in multiple cellular processes, including cell growth, survival, and inflammation. However, whether the PI3 K/ AKT pathway participates in the proinflammatory response of macrophages after particle stimulation and secondary aseptic loosening is still unknown. In this study, ceramic and titanium particles of different sizes were prepared to stimulate macrophages. LY294002, a specific inhibitor of PI3 K, was pretreated prior to particle stimulation. The expression of tumor necrosis factor-alpha ( TNF-α) and all the subunits of PI3 K and AKT were detected by real-time polymerase chain reaction, enzyme-linked immunosorbent assay, and Western blot. The result showed that LY294002 could suppress the RNA and protein expression of TNF-α in RAW264.7 cells after stimulation of different particles. The subunits of PI3 K (p110β and p85β), followed by activation of phosphor- AKT ( Ser473), participated in the regulation of activating macrophages by wear particles, ultimately resulting in the secretion of TNF-α. [ABSTRACT FROM AUTHOR]