中性粒细胞明胶酶相关脂质运载蛋白在狼疮肾炎小鼠模型中的表达及其意义

Expression and significance of NGAL in MRL/lpr lupus-prone mice

目的：探讨中性粒细胞明胶酶相关脂质运载蛋白（NGAL）在 LN 中的表达及其意义。方法36只12周龄的雌性 MRL/lpr 小鼠随机分为实验组和干预组，并以相同周龄的18只雌性昆明小鼠作为对照组。干预组小鼠腹腔注射抗小鼠 IL-17抗体20μg，每2周1次，至实验观察点结束。各组分别于第1次给药后的24 h、14 d 及28 d 处死6只小鼠。 ELISA 法检测小鼠血清 NGAL、IL-17、MMP-9、基质金属蛋白酶组织抑制剂（TIMP）-1的水平，免疫组织化学法检测肾组织 NGAL、IL-17、MMP-9及 TIMP-1的表达水平。组间均数的比较采用单因素方差分析或非参数秩和检验。两因素之间的关系采用 Pearson 相关分析。结果①实验组 MRL/lpr 小鼠血清 NGAL 水平在各时间点均高于对照组和干预组[16周龄（30.31±1.22） ng/ml、（11.36±0.14） ng/ml、（20.09±0.35） ng/ml，F=986.524，P〈0.01]，血清 IL-17、MMP-9、TIMP-1水平在各时间点也均显著高于对照组和干预组（P 均〈0.05）。② NGAL 在实验组小鼠肾小管上皮细胞中的表达明显增强，在各时间点均高于对照组和干预组[16周龄（11.27±0.58）与（0.45±0.19）、（9.22±0.67），F=15.158， P=0.001]，IL-17、MMP-9、TIMP-1在各时间点的表达也均高于对照组和干预组（P 均〈0.05）。③在实验组（16周龄），MRL/lpr 小鼠血清 NGAL 水平和肾脏 NGAL 表达量与 IL-17、MMP-9、MMP-9/TIMP-1水平均呈正相关[血清（r=0.899、0.789、0.925，P〈0.01），肾脏（r=0.929、0.899、0.723，P〈0.01）]。结论 NGAL 在MRL/lpr 狼疮小鼠的血清水平与肾组织中的表达均显著增加，并通过与 IL-17、MMP-9等炎性因子的相互作用而参与 LN 的炎症免疫反应。

Objective To explore the expression and significance of neutrophil gelatinase-associated lipocalin （NGAL） in lupus nephritis （LN） in mice. Methods Female MRL/lpr lupus mice （n=36） were randomly divided into the experimental group and intervention group, and female Kunming mice （n =18） served as controls. Each mice in the intervention group received intraperitoneal injection of 20 μg anti-mice interleukin （IL）-17 antibody. The serum concentrations of NGAL, IL-17,matrix metalloproteinase（MMP）-9 and tissue inhibitor of metalloproteinase （TIMP）-1 were measured by enzyme-linked immunosorbent assay （ELISA）. And the protein expressions of NGAL, IL-17, MMP-9 and TIMP-1 in renal tissue were detected by immunohistochemisty. One-factor analysis of variance （ANOVA） or nonparametric rank sum test was used for the comparisons between the three groups. Associations between these factors were analyzed by Pearson′s test. Results The levels of serum NGAL, IL-17, MMP-9 and TIMP-1 in the experimental group were obviously increased as compared to those in the control group and intervention group [NGAL： （30.31±1.22） ng/ml vs （11.36±0.14） ng/ml, （20.09±0.35） ng/ml, F=986.524, P〈0.001]. The protein expression of NGAL, IL-17, MMP-9 and TIMP-1 in the renal tubular epithelial cells in the experimental group was increased as compared to the control group and intervention group[NGAL：（11.27±0.58） vs（0.45±0.19）,（9.22±0.67）, H=15.158, P =0.001]. In the experimental group, a positive correlation was found between the level of serum NGAL 〈br〉 and the serum levels of IL-17, MMP-9 and MMP-9/TIMP-1（r=0.899, 0.789, 0.925, P〈0.01）. The protein expression of NGAL in renal tissue was positively correlated with IL-17, MMP-9 and MMP-9/TIMP-1 levels （r=0.929, 0.899, 0.723, P〈0.01）. Conclusion The level of NGAL in the serum and renal tissue is signifi-cantly increased in the MRL/lpr lupus mice. And it is closely correlated with the levels of IL-17 and MMP-9. Our results suggest the potential role of NGAL in the inflammation of lupus nephritis.