Study On The Mechanism Of JNK Signal Transduction Pathway In Osteolysis Induced By Wear Particles

Objective At present,artificial joint replacement is one of the most important methods for the treatment of middle and late osteoarthritis,but periprosthetic osteolysis after artificial joint replacement is one of the most important long-term complications.The pathogenesis of periprosthetic osteolysis has become a research hotspot.An animal model of osteolysis induced by titanium particles was established.The role of c-JUN amino terminal kinase(JNK)signal transduction pathway in osteolysis induced by titanium particles was examined by JNK inhibitors.To provide experimental basis for clinical prevention and treatment of periprosthetic osteolysis.Methods Forty-five female BALB/c mice(SPF)were selected.In the Animal Room of the Laboratory Animal Center of Ningxia Medical University(SPF).Forty-five mice were randomly divided into control group,titanium granule stimulation group and titanium granule plus JNK inhibitor group,15 mice in each group.Air pouch model was established by Geng et al.After 14 days,the implanted skull and balloon wall tissues of mice were taken out and specimens were made.HE staining was used to detect inflammation in the implanted skull and balloon wall tissues of mice;TRAP staining was used to detect the number of osteoclasts in the implanted skull and balloon wall tissues of mice;transmission electron microscopy was used to detect the ultrapathological changes of osteoclasts in the implanted skull and balloon wall tissues of mice;immunohistochemistry was used to detect the positive expression of IL-6 protein in the implanted skull and balloon wall tissues of mice.RT-q PCR was used to detect the relative expression of IL-6 mRNA in the implanted skull and balloon wall tissues of mice.Western blotting was used to detect the expression of p-JNK protein in the implanted skull and balloon wall tissues of mice.Results Forty-five BALB/c mice were selected in the experiment.No loss was found during the experiment,and all of them were involved in the result analysis.During the experiment,there was no infection of surgical incision in each group,and there was no significant difference in body mass among the groups.The results of gross morphology and structure observation: the control group,there was no obvious inflammation around the implanted skull tissue;the titanium granule stimulation group,the balloon wall was closely wrapped with titanium granules and implanted skull tissue of mice,the balloon wall was thicker,there was obvious capillary proliferation around the balloon wall,and the inflammation was obvious;the titanium plus JNK inhibitor group,the balloon wall was wrapped up.Titanium particles and implanted mouse skull tissue,compared with the Titanium granule stimulation group,the surrounding capillary proliferation was relatively reduced,and the inflammation performance was reduced.HE staining results: Compared with the control group,there were obvious inflammatory reactions and a large number of inflammatory cells infiltration in tissue samples of Titanium granule stimulation group.Compared with the titanium granule stimulation group,the inflammation response and inflammatory cell infiltration in the titanium granule plus JNK inhibitor group were significantly reduced.The results of TRAP staining showed that the number of TRAP-positive cells in Titanium granule stimulation group was significantly higher than that in control group(14.530 + 2.615)(P < 0.05),while the number of TRAP-positive cells in Titanium granule plus JNK inhibitor group(9.467 + 2.386)was significantly lower than that in Titanium granule stimulation group(14.530 + 2.615)(P < 0.05).The results of transmission electron microscopy showed that the number of osteoclasts in the control group was small,the nucleus was small,the organelles in the cytoplasm had no obvious abnormal changes,and the number of lysosomes was small.In the titanium granule stimulation group,the number of osteoclasts increased significantly,the surface of the cell membrane showed wrinkles,the nucleus enlarged,the cytoplasm was rich,a large number of rough endoplasmic reticulum and mitochondria could be seen in the cytoplasm,and the lysosomes also increased significantly.Osteoclasts are active and adhere to the surface of bone tissue.Osteolytic changes can be seen on the surface of bone tissue.In the titanium granule plus JNK inhibitor group,the number of osteoclasts was less,the rough endoplasmic reticulum,lysosome and mitochondria were also reduced,and the function of osteoclasts was reduced.Immunohistochemical staining showed that the positive expression of IL-6 protein in Tigranule stimulation group was significantly higher than that in control group(0.034+0.010)(P < 0.05),while the positive expression of IL-6 protein in Ti-granule plus JNK inhibitor group was significantly lower than that in Ti-granule stimulation group(0.085+0.023)(P < 0.05).RT-qPCR results showed that IL-6 mRNA expression was detected in all three groups of implanted skulls and their cystic wall tissues.At the same time,the relative expression of IL-6 mRNA in Titanium granule stimulation group was significantly higher than that in control group(7.200+0.890)(P < 0.05),while the relative expression of IL-6 in Titanium granule plus JNK inhibitor group(2.906+1.090)was significantly lower than that in Titanium granule stimulation group(7.200+0.890)(P < 0.05).Western blot showed that the expression of p-JNK protein was detected in all three groups of implanted skulls and their cystic wall tissues.At the same time,the relative expression of pJNK protein in Titanium granule stimulation group was significantly higher than that in control group(1.701 +0.107),while the relative expression of p-JNK protein in Titanium granule plus JNK inhibitor group was significantly lower than that in Titanium granule stimulation group(1.701 +0.107)(P < 0.05).Conclusion JNK signaling pathway plays an important role in wear particles-induced osteolysis.JNK signal transduction pathway can regulate the differentiation and activation of osteoclasts by regulating the expression of IL-6,and then control inflammatory osteolysis.