BYL-719对结核杆菌诱导异常破骨细胞分化的作用及机制

Effect and mechanism of BYL-719 on Mycobacterium tuberculosis-induced differentiation of abnormal osteoclasts

背景:PI3K/AKT信号通路调控破骨激活在维持骨稳态中具有关键作用,而骨关节结核中的骨质破坏正是由于结核杆菌感染引起的异常破骨细胞生成所致,但是PI3K信号通路在结核杆菌诱导的异常破骨细胞生成中发挥的作用尚不明确。目的:探究PI3K/AKT信号通路抑制剂BYL-719对结核杆菌诱导的异常破骨细胞生成的影响及机制。方法:使用牛结核杆菌卡介苗(BCG)感染RAW264.7细胞,Ag85B进行细胞免疫荧光染色;CCK-8法确定BYL-719安全使用浓度。实验分为空白对照组、BYL-719组、卡介苗组、卡介苗+BYL-719组。各组细胞在RANKL诱导下,通过抗酒石酸酸性磷酸酶染色和鬼笔环肽染色,探究BYL-719对结核杆菌感染后破骨细胞分化、融合的影响;RT-PCR和Western Blot检测破骨细胞相关基因及蛋白表达情况,并进一步探索作用机制。结果与结论:①免疫荧光染色结果显示,RAW264.7细胞吞噬结核杆菌;②CCK-8数据显示,40 nmol/L浓度BYL-719没有细胞毒性;③抗酒石酸酸性磷酸酶染色和鬼笔环肽染色提示,BYL-719能抑制结核杆菌感染后的破骨细胞生成、融合能力;④RT-PCR和Western blot结果也提示,BYL-719抑制了结核杆菌感染诱导的破骨细胞特异性基因(包括c-Fos、NFATc1、基质金属蛋白酶9和CtsK)表达升高(P<0.05);⑤Western blot和免疫荧光染色结果揭示,BYL-719通过下调IκBα-p65来抑制结核杆菌诱导的破骨细胞过度分化;⑥结论:BYL-719通过下调IκBα/p65抑制结核杆菌诱导的异常破骨细胞生成,说明IκBα/p65信号通路是骨关节结核潜在治疗靶点,BYL-719有预防和改善骨关节结核中骨质破坏的潜在价值。

BACKGROUND:The phosphatidylinositol 3-kinase/protein kinase(PI3K/AKT)signaling pathway plays a pivotal role in regulating osteoclast activation,which is essential for maintaining bone homeostasis.Bone destruction in osteoarticular tuberculosis is caused by aberrant osteoclastogenesis induced by Mycobacterium tuberculosis infection.However,the role of the PI3K signaling pathway in Mycobacterium tuberculosis-induced aberrant osteoclastogenesis remains unclear.OBJECTIVE:To investigate the effects and mechanisms of the PI3K/AKT signaling pathway inhibitor BYL-719 on aberrant osteoclastogenesis induced by Mycobacterium tuberculosis.METHODS:RAW264.7 cells were infected with bovine Mycobacterium tuberculosis bacillus calmette-cuerin vaccine,and Ag85B was used for cellular immunofluorescence staining.The cell counting kit-8 assay was employed to determine the safe concentration of BYL-719.There were four groups in the experiment:blank control group,BYL-719 group,BCG group,and BCG+BYL-719 group.Under the induction of receptor activator of nuclear factor kappa-B ligand,the effects of BYL-719 on post-infection osteoclast differentiation and fusion were explored through tartrate-resistant acid phosphatase staining and phalloidin staining.RT-PCR and western blot were used to detect the expression of osteoclast-related genes and proteins,and further investigate the mechanism of action.RESULTS AND CONCLUSION:Immunofluorescence staining showed that RAW264.7 cells phagocytosed Mycobacterium tuberculosis.Cell counting kit-8 data indicated that 40 nmol/L BYL-719 was non-toxic to cells.Tartrate-resistant acid phosphatase staining and phalloidin staining showed that BYL-719 inhibited the generation and fusion ability of osteoclasts following infection.RT-PCR and western blot results also indicated that BYL-719 suppressed the upregulation of osteoclast-specific genes(including c-Fos,NFATc1,matrix metalloproteinase 9,and CtsK)induced by Mycobacterium tuberculosis infection(P<0.05).Western blot and immunofluorescence staining revealed that BYL-719 inhibited excessive osteoclast differentiation induced by Mycobacterium tuberculosis by downregulating the expression of IκBα-p65.To conclude,BYL-719 inhibits aberrant osteoclastogenesis induced by Mycobacterium tuberculosis through the downregulation of IκBα/p65.Therefore,the IκBα/p65 signaling pathway is a potential therapeutic target for osteoarticular tuberculosis,and BYL-719 holds potential value for the preventing and amelioration of bone destruction in osteoarticular tuberculosis.BYL-719 has the potential to prevent and ameliorate bone destruction in osteoarticular tuberculosis.