Role of cannabinoid receptor 2 selective antagonist in titanium particles-induced inflammatory osteolysis

Abstract

Objective To explore the therapeutic effect of selective antagonist-AM630 of cannabionid receptor 2 (CB2) in treatment of the titanium particles-induced inflammatory osteolysis. Methods Forty-five female BALB/c mice, 6-8 weeks old, were involved in the study, of which 15 mice were used as skull donors and the rest experimental animals were randomly divided into three groups, ie, black group, control group and treatment group, 10 mice per group.The mice model with air-pouch osteolysis induced by the titanium particles were established.The mice in the treatment group were injected with CB2 selective antagonist-AM630 (200 μg · kg-1 · d-1) intraperitoneally from two days before establishment of the air-pouch osteolysis model to two weeks after establishment of the model.Then, the mice were sacrificed and the pouch tissues were collected for molecular and histological analyses.The pouch membrane thickness and cell infiltration were tested by using computerized image analysis system and HE staining respectively.Osteoclast-like cells in the pouch membrane were determined by using tartrate-resistant acid phosphatase (TRAP) staining.Quantitative real-time polymerase chain reaction (RT-PCR) was employed to detect the mRNA levels of CB2, IL-1 β, TNF-α, receptor activator of NF-κB ligand (RANKL)and receptor activator of NF-κB (RANK).Results There exhibited apparent erythematous and oedematous changes in the control group, which was mitigated around the bone implants with AM630 treatment.Quantitative image analysis of the histological sections revealed significant difference of the pouch membrane thickness among three groups, (192.2 ± 19.4) μm in control group, (88.5 ± 14.7) μm in blank group and (122.1 ± 15.2) μm in treatment group (F = 101.74, P ＜ 0.05).Intensive TRAP staining was identified much in the control group but markedly reduced after AM630 treatment in the pouch tissues.RT-PCR showed that titanium particle stimulation could enhance the expressions of CB2, IL-1 β, TNF-α, RANKL and RANK gene in the air pouch tissues.However, the mRNA levels of these genes were markedly reduced after AM630 treatment, with statistical difference compared with control group (P ＜ 0.05). Conclusions CB2 selective antagonist AM630 can inhibit the process of titanium particlesstimulated inflammatory reaction and osteoclast activation.Therefore, CB2 represents a new suitable therapeutic candidate for the prevention and treatment of aseptic loosening of the artificial joint. Key words: Joint prothesis ; Prosthesis failure; Wear debris; Osteoclast