MIP-1α在多发性骨髓瘤中导致骨质破坏的可能机制研究

Possible mechanism of MIP-1αcausing bone destruction in multiple myeloma

目的建立多发性骨髓瘤(MM)小鼠模型,分析巨噬细胞炎症蛋白1α(MIP-1α)对小鼠骨质破坏可能的影响机制。方法取非肥胖型糖尿病/重症联合免疫缺陷(NOD/SCID)雌性小鼠24只,随机分为常规建模组、建模抑制组与空白对照组共三组,各组均8只。除空白对照组外,另两组接种RPMI 8226细胞混悬液建立MM小鼠模型。建模抑制组建模成功后经皮下注射Y-27632通路抑制剂,其余两组注射同体积生理盐水,连续注射1周。实验终末期,对各组小鼠进行免疫组化、X线及MIP-1α、骨源性碱性磷酸酶(BALP)、Ras同源基因家族蛋白A(RhoA)/Rho相关螺旋卷曲蛋白激酶(ROCK)表达水平检测,分析MIP-1α对MM建模小鼠骨质破坏的可能影响机制。结果MM常规建模组小鼠观察时间内下肢瘫痪6例(75.00%),建模抑制组下肢瘫痪4例(50.00%)。较之于空白对照组,常规建模组病理切片视野下可见恶性浆细胞,破骨细胞明显增多、骨质破坏严重、胫骨周围组织明显肿大,但接受Y-27632通路抑制剂的建模抑制组破骨细胞减少,骨质破坏轻微,胫骨周围有微肿胀软组织影。MIP-1α表达水平比较,常规建模组(332.80±85.60)pg/ml、建模抑制组(296.40±67.54)pg/ml较空白对照组(8.40±2.36)pg/ml均有显著增高(P<0.01);且常规建模组小鼠的BALP水平降低,RhoA与ROCK1表达水平上升,与空白对照组比较差异有统计学意义(P<0.05);应用Y-27632通路抑制剂后小鼠MIP-1α表达水平降低,BALP回升,RhoA与ROCK1表达被抑制而降低(P<0.05)。结论MIP-1α可能是通过RhoA/ROCK1信号通路对MM建模小鼠的骨质造成破坏,因此抑制MIP-1α表达水平,对延缓MM小鼠的骨质破坏、延长生存期有重要意义。

Objective To analyze the influence mechanism of macrophage inflammatory protein 1α(MIP-1α)in bone destruction in mice by establishing the mouse model of multiple myeloma(MM).Methods Twenty-four non-obese diabetic/severe combined immunodeficiency(NOD/SCID)female mice were randomly divided into three groups:conventional modeling group,modeling inhibition group and blank control group(n=8,each).Except for blank control group,the mice of other two groups were inoculated with RPMI 8226 cell suspension to establish MM mouse models.After successfully modeling,Y-27632 pathway inhibitor was injected subcutaneously in modeling inhibition group,and the same volume of normal saline was injected in other two groups for 1 week.At the end of the experiment,the mice in each group were subjected to immunohistochemistry,X-ray and the expression levels of MIP-1α,bone alkaline phosphatase(BALP),RhoA and ROCK1 to analyze the possible influence mechanism of MIP-1αon the bone destruction of MM model mice.Results There were 6 cases of lower limb paralysis(75.00%)in conventional modeling group and 4 cases of lower limb paralysis(50.00%)in modeling inhibition group.Compared with blank control group,malignant plasma cells,increased osteoclasts,serious bone destruction and surrounding soft tissue swelling appeared obviously in the visual field of pathological slices in conventional modeling group.However,there were decreased osteoclast number,with slightly damaged bone and slightly swollen soft tissue shadow around tibia bone in inhibition modeling group.The expression levels of MIP-1αin conventional modeling group[(332.80±85.60)pg/ml]and in inhibition modeling group[(296.40±67.54)pg/ml]were significantly higher than that[(8.40±2.36)pg/ml]in blank control group(P<0.01).Compared with those in blank control group,BALP level decreased,and RhoA and ROCK1 levels increased in conventional modeling group(P<0.05).However,in modeling inhibition group,MIP-1αexpression decreased to some extent,BALP level increased,and the expression levels of RhoA and ROCK1 were significantly decreased because of pathway inhibitor Y-27632.Conclusions MIP-1αmay play roles in bone destruction of MM model mice through the RhoA/ROCK1 signaling pathway.Therefore,inhibiting the expression of MIP-1αis of great significance for reducing bone destruction and prolonging the survival of MM mice.