B细胞激活因子通过磷脂酰肌醇3-激酶／蛋白激酶B/哺乳动物雷帕霉素靶蛋白信号通路参与狼疮肾炎患者发病机制的研究

B-cell activating factor involved in the pathogenesis of lupus nephritis through regulating phosphoino- sitide 3-kinase/protein kinase B/mammalian target of rapamycin signaling

目的探讨B细胞激活因子（BAFF）通过磷脂酰肌醇3-激酶／蛋白激酶B／哺乳动物雷帕霉素靶蛋白（P13K／Akt／mTOR）信号通路参与LN发病的作用机制。方法LN组为28例确诊LN患者，对照组为20例因肾脏良性肿瘤行一侧肾切除的患者，收集2组患者的临床资料[包括ESR、CRP、补体c3、尿蛋白定量（24h）、血肌酐、尿素氮]及LN组患者的抗dsDNA抗体定量指标。ELISA法检测2组血浆BAFF水平，分析LN组血浆BAFF表达水平与疾病活动的相关性；实时荧光定量PCR和蛋白质印迹法分别检测。肾脏组织BAFF、磷酸化（p）。P13K、p-Akt、p-roTOR、Bcl-2mRNA和蛋白表达水平。采用Mann—Whitney秩和检验及Spearman相关分析进行统计学分析。结果①LN组患者血浆BAFF表达水平[（580±45）ng/L]显著高于对照组[（208±30）ng／L]（Z=5．856，P〈O．01）；且与SLEDAI评分呈正相关（r=0．723，P〈0．01）。②LN患者血浆BAFF水平与尿蛋白定量（24h）、抗dsDNA抗体定量均呈正相关（r=0．381、0．461，P〈0．05）；LN患者肾组织BAFF水平与尿蛋白定量（24h）、抗dsDNA抗体定量均呈正相关（r=0．469、0．489，P〈0．05）。③LN组肾脏组织中BAFF、P．P13K、P．Akt、P．mTOR、Bcl-2mRNA的表达水平均高于对照组[5．8±1．8与2．1±0．7，Z=-4．915，P〈0．01；6．7±0．9与1．7±0．5，z=-5．857，P〈0．01；5．6＋0．9与1．8±0．5，Z=-5．751，P〈O．01；5．6±1．4与1．6±0．4，Z=-5．291，P〈0．01；2．11±0．36与1．33±0．22，Z=-4．844，P〈0．01]。④LN组肾脏组织中BAFF、p．P13K,p-Akt、p．mTOR、Bcl-2蛋白表达水平均高于对照组[0．72±0．19与0．31±0．05，Z=-4．747，P〈0．01；0．73±0．11与O．33±0．09，Z=-5．834，P〈O．01；0．77±0．06与O．22±0．07，Z=-5．855，P〈0．01；1．18±0．27与0．47±0．13，Z=-5．416，P〈0．01；2．08±0．37与1．32±0．18，Z=-4．998，P〈O．011o结论LN患者血浆及肾组织中BAFF表达显著增高，伴有P13K／Akt／mTOR信号通路的激活，提示BAFF可能通过P13K／Akt／mTOR信号通路参与LN患者的发病。

Objective To investigate whether B-cell activating factor （BAFF） involved in the patho- genesis of lupus nephritis （LN） by regulating phosphoinositide 3-kinase/protein kinase B/mammalian target of rapamycin （PI3K/Akt/mTOR） signaling. Methods Twenty-eight lupus nephritis patients and 20 controls were included in this study. The clinical data were collected. BAFF levels in plasma were measured by ELISA, and the relationship between systemic lupus erythematosus disease activity index （SLEDAI） and BAFF were analyzed. The mRNA and protein levels of BAFF, phosphorylated-PI3K （p-PI3K）, phosphorylated-Akt （p-Akt）, phosphorylated-mTOR （p-mTOR） and Bcl-2 in kidney tissues were measured using real-time polymerase chain reaction （RT-PCR） and Western blotting. Data were analyzed using Mann-Whitney U test and Spearman correlation analysis. Results （1） Plasma BAFF levels were significantly higher in LN patients [（580±45） ng/L] compared with controls [（208±30） ng/L]（Z=-5.856, P〈0.01）, and significant positive correlation was found between plasma BAFF levels with SLEDAI （r=0.723, P〈0.01）. （2） Plasma BAFF level in LN patients was positively correlated with 24 h UP and anti-dsDNA titers （r=0.381, 0.461, P〈0.05）. The protein level of BAFF in kidney tissues was positively correlated with 24 h UP and anti-dsDNA titer （r=0.469, 0.489, P〈0.05）. （3） The mRNA levels of BAFF, p-PI3K, p-Akt, p-mTOR and Bcl-2 in kidney tissues were increased in patients compared to controls[5.8±1.8 vs 2.1±0.7, Z=-4.915, P〈0.01; 6.7±0.9 vs 1.71±0.53, Z=-5.857, P〈0.01; 5.6±0.9 vs 1.8±0.5, Z=-5.751, P〈0.01; 5.6±1.4 vs 1.6±0.4, Z=-5.291, P〈0.01; 2.11±0.36 vs 1.33±0.22, Z=-4.844, P〈0.01]. （4）The protein levels of BAFF, p-PI3K, p-Akt, p-mTOR and Bcl-2 in kidney tissues were increased in patients compared to controls [0.72±0.19 vs 0.31±0.05, Z=-4.747, P〈0.01; 0.73±0.11 vs 0.33±0.09, Z=-5.834, /9〈0.01; 0.77±0.06 vs 0.22±0.07, Z=-5.855, P〈0.01; 1.18±0.27 vs 0.47±0.13, Z=-5.416, P〈0.01; 2.08±0.37 vs 1.32±0.18, Z=-4.998, P〈0.01]. Conclusion The findings of this study indicate that BAFF may participate in the pathogenesis of LN by regulating PI3K/Akt/mTOR signaling.