p38 MAPK在钛颗粒诱导的破骨细胞形成中的作用

Effects of p38 MAPK on titanium particle-induced osteoclast formation

摘要:

目的：探讨p38 丝裂原活化蛋白激酶（p38 mitogen-activated protein kinase，p38 MAPK）在钛颗粒诱导的破骨细胞形成中的作用。方法：提取小鼠骨髓细胞，接种于24孔板后分为3组：①空白对照组；②核因子κB受体活化因子配体（receptor ac－tivator for nuclear factor-κB ligand，RANKL）组：每孔加入50 ng/ml RANKL；③钛颗粒+RANKL组：每孔加入0.01%钛颗粒悬液（0.1 mg/ml）及RANKL 50 ng/ml，抗酒石酸酸性磷酸酶（tartrate-resistant acid phosphatase，TRAP）染色鉴定和计数破骨细胞。Western blot检测p38、磷酸化p38的表达水平，通过腺病毒介导的p38 siRNA沉默p38的表达后，观察破骨细胞数目及相关蛋白RANK的变化情况。结果：各组破骨细胞计数结果分别为：空白对照组2.0±0.8，RANKL组62.8±5.6，钛颗粒+RANKL组93.0±8.8（F=235.193，P=0.000）。RANKL组高于空白对照组（P=0.000），钛颗粒+RANKL组明显高于RANKL组（P=0.000）。Western blot结果显示钛颗粒能明显提高p38的磷酸化水平（p-p38/p38相对值： 空白对照组0.29±0.05，RANKL组0.64±0.05，钛颗粒+RANKL组 0.87±0.05，F=106.491，P=0.000，钛颗粒+RANKL组高于空白对照组和RANKL组P1=0.000，P2=0.001）。转染腺病毒介导的p38 siRNA后，Ad-sip38干扰组RANK蛋白的表达水平低于对照组和Ad-RFP组，破骨细胞数目也明显低于对照组和Ad-RFP组（破骨细胞计数：对照组99.8±13.5，Ad-RFP组95.8±7.1，Ad-sip38组3.8±2.5，F=148.654，P=0.000，对照组与Ad-RFP组无明显差异P=0.541，Ad-sip38处理组与对照组和空白病毒组比较均P=0.000）。结论：p38 MAPK在钛颗粒诱导的破骨细胞形成中起重要的作用。

Abstract:

Objective：To investigate the effects of p38 mitogen-activated protein kinase on titanium（Ti） particle-induced osteoclast formation. Methods：Bone marrow cells were collected from the femur and tibiae of 4-6 week-old BALB/C mice and were divided in－to three groups：①control group；②receptor activator for nuclear factor-κB ligand（RANKL） treated group；③Ti particle and RANKL treated group. The numbers of osteoclasts were measured by the tartrate-resistant acid phosphatase（TRAP） staining. The expression and phosphorylation level of p38 protein were determined by Western blot. Then an adenovirus-mediated RNA interference targeting p38 was employed to knock down the expression of p38 and the numbers of osteoclasts were determined by TRAP staining；the ex－pression of osteoclast specific gene RANK was detected using Western blot. Results：TRAP staining showed that the numbers of os－teoclasts were significantly higher in Ti particle treated group than in control group with the same concentration of RANKL（blank group：2.0±0.8，RANKL group：62.8±5.6，Ti particle +RANKL group：93.0±8.8，F=235.193，P=0.000）（RANKL group vs. blank group，P=0.000；Ti particle+RANKL group vs. RANKL group，P=0.000）. The relative phosphorylation level of p38 was significantly improved in Ti particle and RANKL treated group compared with that in control group and RANKL treated group（blank group：0.29±0.05，RANKL group：0.64±0.05，Ti particle+RANKL group：0.87±0.05，F=106.491，P=0.000）（Ti particle+RANKL group vs. blank group and RANKL group，P1=0.000，P2=0.001）. After being treated with adenovirus-mediated p38 siRNA（Ad-sip38），the number of osteo－clasts and the protein level of RANK were remarkably decreased（TRAP positive cells：control group：99.8±13.5，Ad-RFP group：95.8±7.1，Ad-sip38 group：3.8±2.5）（control group vs. Ad-RFP group，P=0.541；Ad-sip38 group vs. control group and Ad-RFP group，P1=0.000，P2=0.000）. Conclusion：p38 MAPK plays an impor－tant role in the osteoclast formation induced by Ti particle.