结核杆菌侵染破骨细胞对骨质破坏相关因子表达影响的体外研究

An in vitro study of the effect of Mycobacterium tuberculosis infection on the expression of bone destruction-related factors in osteoclasts

目的:建立结核杆菌侵染破骨细胞(osteoclasts,OC)模型,探讨结核杆菌侵染OC后对骨质破坏相关因子表达的影响。方法:采集健康志愿者的外周全血,分离出外周全血中的单核细胞(peripheral blood mononuclear cells,PBMCs),利用核因子κB受体活化因子配体(receptor activator of nuclear factor-κB ligand,RANKL)以及巨噬细胞集落刺激因子(macrophage-colony stimulating factor,M-CSF)诱导使其成为OC,对细胞进行抗酒石酸酸性磷酸酶(tartrate resistant acid phosphatase,TRAP)染色。将已经构建好的具有卡那霉素(Kana)抗性的H37Rv pMV261-GFP绿色荧光结核菌株进行复苏并加入10%的油酸、白蛋白、葡萄糖和过氧化氢酶添加剂(oleic albumin dextrose catalase,OADC)、7H9以及含卡那霉素的结核杆菌专用液体培养基进行培养,放置于37℃的恒温箱中培养至光密度(optical density,OD)值为600nm时的0.5左右备用;以单纯OC培养为空白对照组;用结核杆菌以不同转染复数(multiplicity of infection,MOI)侵染OC 24h,采用MTT比色法检测细胞存活率最高的MOI为后续实验MOI,使用H37Rv以此MOI侵染OC为实验组;荧光显微镜及结核杆菌抗酸染色分别观测实验MOI时结核杆菌转染情况。实时荧光定量PCR(real time fluorescence quantitative PCR,qRT-PCR)检测非受体酪氨酸激酶(C-src)、蛋白激酶K(cathepsin K,CK)、碳酸酐酶2(carbonic anhydrase 2,CA2)、整合素-β3(integrin-β3)、基质金属蛋白酶-9(matrix metalloproteinase-9,MMP-9)的表达情况;免疫组化(immunohistochemistry)检测磷酸化酪氨酸激酶产物(P-src)、CK、CA2、Integrin-β3、MMP-9的细胞表面蛋白表达情况;蛋白免疫印迹(western blot,WB)检测P-src、CK、CA2、Integrin-β3、MMP-9的蛋白表达水平。结果:TRAP染色显示细胞培养15d后90%以上为OC,可以用于进行实验。荧光结核杆菌成功将其OD值培养为600nm时的0.5。MTT比色法结果显示:在MOI为20∶1时细胞存活率最高(P<0.05),此为实验组MOI;结核杆菌侵染OC后荧光显微镜显示:MOI为20∶1时,绿色荧光标记的结核杆菌进入OC,说明成功转染OC;结核杆菌侵染OC后抗酸染色结果显示:MOI为20∶1时,被染成红色的抗酸结核杆菌进入OC,说明结核杆菌H37Rv成功转染OC。qRT-PCR、细胞免疫组化、WB检测结果均显示:MMP-9、CK、C-src、CA2、Integrin-β3的表达实验组均高于空白对照组(P<0.05)。结论:结核分枝杆菌能够转染OC;与空白对照组相比,结核杆菌转染OC的实验组中5种具有骨质破坏作用因子均升高,提示结核骨质破坏可能与此相关,为骨结核疾病诊疗提供新的探索方向。

Objectives:To establish a model of Mycobacterium tuberculosis infection of osteoclasts(OC)and explore the mechanism of Mycobacterium tuberculosis infection on OC.Methods:Peripheral blood mononuclear cells(peripheral blood mononuclear cells,PBMCs)were isolated from healthy volunteers.Receptor activator of nuclear factor-κB ligand(RANKL)and macrophage-colony stimulating factor(M-CSF)were used to make PBMCS into OC,and tartrate resistant acid phosphatase(TRAP)staining was performed on the cells.The constructed kanamycin resistant H37Rv pMV261-GFP green fluorescent strain was resuscitated and cultured with 10%oleic albumin dextrose catalase(OADC),7H9 and kanamycin containing Mycobacterium tuberculosis special liquid medium in an incubator at 37℃until the optical density(OD)value was about 0.5 at 600nm.The OC cells cultured alone were set as the blank control group.And OC cells were also infected with Mycobacterium tuberculosis at different multiplicity of infection(MOI)for 24h,and MTT colorimetric method was used to detect cell survival rate.The MOI with the highest cell survival rate was selected as experimental MOI,and OC cells infected with H37Rv at experimental MOI were set as the experimental group.Fluorescence microscopy and Mycobacterium tuberculosis acid-fast staining were used to observe the transfection of Mycobacterium tuberculosis at the experimental MOI.Quantitative real-time PCR(qRT-PCR)was used to detect the expressions of non-receptor tyrosine kinase C-src,cathepsin K(CK),carbonic anhydrase 2(CA2),Integrin-β3 and matrix metalloproteinase-9(MMP-9).Immunohistochemistry was used to detect the expressions of P-src,CK,CA2,Integrin-β3 and MMP-9 on the cell surface.Western blot(WB)was used to detect the protein expression levels of P-src,CK,CA2,Integrin-β3,and MMP-9.Results:TRAP staining showed that more than 90%of the cells were OC after 15d of culture,which could be used for experiments.The results of MTT colorimetric assay showed that the cell survival rate was the highest when the MOI was 20∶1(P<0.05).This transfection multiplicity can be used as the concentration of experimental group.Fluorescence microscopy showed that when the transfection multiplicity ratio was 20∶1,the green fluorescent Mycobacterium tuberculosis entered the OC and was successfully transfected into the OC.The results of acid-fast staining after infection of OC with Mycobacterium tuberculosis showed that when the MOI was 20∶1,the acid-fast Mycobacterium tuberculosis stained red entered OC and was also successfully transfected into OC.The results of qRT-PCR,cell immunohistochemistry,and WB showed that the expressions of MMP-9,CK,C-src,CA2,and Integrin-β3 in the experimental group were higher than those in the blank control group(P<0.05).Conclusions:Mycobacterium tuberculosis can transfect OC;Compared with the blank control group,the levels of five bone destruction factors in the experimental group transfected with OC by Mycobacterium tuberculosis were increased,suggesting that bone destruction of spinal tuberculosis may be related to this,which may provide a new exploration direction for the diagnosis and treatment of bone tuberculosis diseases.