Linagliptin alleviates wear particle-induced inflammatory osteolysis by regulating macrophage polarization and osteoclast formation

Yang Peng; Zhang Wei; Li Wenming; Li Wenhao; Wu Zebin; Zhou Jun; Geng Dechun

doi:10.12307/2025.393

Abstract：BACKGROUND:Linagliptin exhibits the capacity to regulate macrophage polarization,shifting them from the pro-inflammatory M1 phenotype towards the anti-inflammatory M2 phenotype. This alteration results in a dampened release of inflammatory mediators,thereby mitigating local inflammation. OBJECTIVE:To explore the effects of linagliptin on macrophage polarization,osteoclast activation,and inflammatory osteolysis elicited by wear particles. METHODS:(1) Cell experiments:For macrophage polarization,RAW264.7 cells were cultured and divided into four groups:the control group received high-glucose culture medium;the M1-induced group received M1-inducing culture medium (high-glucose culture medium containing 100 ng/mL lipopolysaccharide and 20 ng/mL interferon-γ) to simulate an inflammatory environment;the low-and high-dose linagliptin groups were treated with 50 and 200 nmol/L linagliptin,respectively,for 4 hours before exposure to M1-inducing culture medium. After 24 hours of macrophage polarization induction,immunofluorescence staining and RT-PCR were performed. For osteoclast activation,RAW264.7 cells were cultured and divided into four groups:the control group was cultured with high-glucose culture medium,the osteoclast-induced group and low-and high-dose linagliptin groups were subjected to osteoclast induction. After osteoclast formation,cells were treated with linagliptin (50 and 200 nmol/L) for 3 days. Subsequently,cell tartrate-resistant acid phosphatase staining and RT-PCR were performed. (2) Animal experiments:Twenty-four male C57BL/6J mice were randomly divided into four groups:sham operation group,model group,low-dose linagliptin group,and high-dose linagliptin group. The model group,low-dose linagliptin group,and high-dose linagliptin group were induced to establish a cranial bone resorption model by injecting titanium particle suspension onto the surface of the skull. Starting from the 2nd day after modeling,the low-and high-dose linagliptin groups were orally administered linagliptin (2 and 10 mg/kg,respectively) once daily. After modeling for 3 weeks,serum macrophage polarization marker protein and inflammatory factor levels were detected;skull samples were collected for micro-CT scanning,bone parameter analysis,and hematoxylin-eosin staining to evaluate osteolysis and morphological changes. RESULTS AND CONCLUSION:(1) Cell experiments:Both low and high doses of linagliptin significantly suppressed M1 polarization while promoting M2 polarization compared to the M1-induced group (P<0.01). Notably,the high-dose group exhibited a more pronounced inhibitory effect (P<0.01). Inflammatory factor mRNA expression was elevated in the M1-induced group compared with the control group (P<0.01),whereas inflammatory factor mRNA expression was significantly lower in the low-and high-dose linagliptin groups compared with the M1-induced group (P<0.01). There was a significant upregulation of mRNA expression of osteoclast functional markers in the osteoclast-induced group compared with the control group (P<0.01). Conversely,both low and high doses of linagliptin led to a substantial downregulation of mRNA expression of these markers compared with the osteoclast-induced group (P<0.01),with the high-dose group exhibiting a more pronounced reduction. (2) Animal experiments:Titanium particle implantation induced cranial bone resorption damage in mice. Treatment with linagliptin effectively mitigated this bone resorption,with the high-dose group showing superior efficacy. To conclude,linagliptin has been shown to modulate macrophage polarization,inhibit osteoclast activation,and have a protective effect on the skeletal system.