miR-155在免疫性血小板减少症发病机制中的作用

The role of miR-155 in pathogenesis of immune thrombocytopenia

目的通过观察免疫性血小板减少症（ITP）患者外周血CD19＋B细胞中微小RNAl55（miR-155）的表达与B淋巴细胞功能的关联性，探讨miR-155在ITP发病机制中的作用。方法选取2014年12月至2015年10月天津医科大学总医院血液科住院的初诊ITP患者30例（初诊组）、完全缓解ITP患者25例（完全缓解组）为研究对象，健康志愿者25名为对照组。采取免疫磁珠法分离CD19＋B细胞，实时荧光定量PCR检测miR-155的表达，流式细胞术检测CD19＋B细胞内IgG、IgM、含SH2结构的5’肌醇磷酸酶-1（SHIP-1）的表达，并与其临床指标进行相关性分析。结果（1）初诊组ITP患者CD19＋B细胞中miR-155的表达水平（4．57±1．03）显著高于完全缓解组（0．79．4-0．13）和健康对照组（1．74±0．32），完全缓解组低于健康对照组（均P〈0．05），且初诊组患者中治疗有效的ITP患者初诊时miR-155的表达水平（3．85±0．71）低于难治患者初诊时miR-155的表达水平（6．67±1．05）（P〈0．05）。（2）初诊组CD19-B细胞中IgG、IgM表达水平（35．20％±6．19％、26．87％．±5．01％）显著高于完全缓解组（7．51％±1．91％、5．93％±2．23％）和健康对照组（8．23％±0．68％、8．21％±1．08％）（均P〈0．05）。（3）初诊组患者CD19＋B细胞中SHIP-1的表达水平（44．33％±3．95％）显著低于完全缓解组（83．13％±3．24％）和健康对照组（67．26％±3．73％），完全缓解组高于健康对照组（均P〈0．05）。（4）ITP患者CD19＋B细胞中miR-155的表达水平与B1细胞（CD19＋CD5＋B细胞）数量呈正相关（r=0．576，P〈0．05），与SHIP-1的表达量及外周血血小板计数呈负相关（r=-0．445、-0．402，均P〈0．05）。结论miR-155在ITP患者外周血的CD19＋B中异常高表达，并与B淋巴细胞功能紊乱及胞内抗体产生有关，提示其可能参与TP的发病。

Objective To explore the role of microRNA-155 （ miR-155 ） in pathogenesis of immune thrombocytopenia （ITP） through investigate the relevance between the expression of miR-155 in CD19 ＋ B cells in peripheral blood and the function of B lymphocytes in patients with ITP. Methods A total of 55 ITP patients （30 newly diagnosed and 25 in remission） were collected from December 2014 to October 2015 in Tianjin Medical University General Hospital, and 25 healthy volunteers were recruited as controls. The CD19 ＋ B cells were extracted by immunomagnetic microbeads. The expression of miR-155 in CD19 ＋ B cells were detected by real-time fluorescent quantitative PCR. The levels of IgG, IgM and SH2 domain-containing inositol 5＇-phosphatase 1 （SHIP-1） in CD19 ＋B cells were measured by flow eytometry （FCM）. Correlation between miR-155 and clinical parameters of ITP patients was analyzed. Results （ 1 ） The expression of miR-155 in CD19 ＋B cells in newly diagnosed ITP patients （4. 57 ± 1.03 ） was significantly higher than that in remitted ITP patients （0. 79 ± 0. 13 ） and controls （ 1.74 ± 0. 32）, and that in the remitted ITP patients was lower than in the controls （all P 〈 0. 05）. In addition, the level of miR-155 at initial diagnosis in the patients responding to treatment （3.85 ± 0. 71 ） was lower than that in the refractory patients （6. 67 ± 1.05 ） （P 〈 0. 05 ）. （2） The levels of IgG and IgM in CD19 ＋ B cells in newly diagnosed ITP patients （35.20% ± 6. 19%, 26. 87% ± 5.01% ） were significantly higher than those in remitted ITP patients （7.51% ± 1.91%, 5.93% ±2.23%） and controls （8.23%±0.68%, 8.21%±1.08%） （allP〈0.05）. （3） The expression of SHIP-1 in CD19＋ B cells in newly diagnosed ITP patients （44. 33% ± 3.95% ） was significantly lower than that in remitted ITP patients （83.13% ±3.24% ） and controls （ 67.26% ± 3.73% ）, and that in the remitted ITP patients was higher than in controls （ all P 〈 0. 05 ）. （4） The expression level of miR-155 in CD19 ＋ B cells in ITP patients was positively correlated with CD19 ＋ CD5 ＋ B cell count （r =0. 576, P 〈0. 05）, and negatively correlated with the level of SHIP-1 and peripheral platelet count （r = -0. 445, -0. 402, all P 〈 0. 05）. Conclusion There is abnormally high expression of miR- 155 in CD19 ＋ B cells in peripheral blood of ITP patients, which is related with the dysfunction of B lymphocytes and ntracellular antibody production, suggesting that miR-155 might be involved in the pathogenesis of ITP.