白细胞介素7受体α抗体减轻MRL/lpr狼疮小鼠肾脏损伤的免疫调节机制

Immunomodulatory mechanism of interleukin-7 receptorαantibody attenuating renal injury in MRL/lpr lupus mice

目的探讨白细胞介素(interleukin, IL)-7受体α抗体对MRL/lpr狼疮小鼠免疫炎症和肾脏损伤的作用。方法 15只体重15~16 g无特定病原体3~4周龄雌性MRL/lpr小鼠饲养至14周龄, 随机分为IL-7受体α抗体干预组、IL-7受体α同型抗体组(阳性对照组)和生理盐水组(阴性对照组), 分别腹腔注射IL-7受体α抗体、同型抗体和生理盐水, 每周3次, 每次100 μg, 共4周。18周龄时处死小鼠, 考马斯亮蓝法检测24 h尿蛋白量;过氧化物酶法检测血清肌酐;酶联免疫吸附测定法检测自身抗体(抗双链DNA抗体)、炎性因子肿瘤坏死因子α、γ干扰素、IL-21的表达;PAS染色和天狼星红染色检测肾组织病理;免疫组化法检测肾组织CD3、F4/80的表达;流式细胞术检测调节性T细胞、囊泡样辅助性T细胞(follicular helper T cells, Tfh)和囊泡样调节性T细胞(follicular regulatory T cells, Tfr)亚群并计数。结果与生理盐水组和IL-7受体α同型抗体组比较, IL-7受体α抗体干预组24 h尿蛋白量及血清肌酐、抗双链DNA抗体、γ干扰素、IL-21均降低(均P<0.01), 但三组间血清肿瘤坏死因子α的差异无统计学意义(F=0.39, P>0.05)。与生理盐水组和IL-7受体α同型抗体组比较, IL-7受体α抗体干预组肾脏组织CD3和F4/80阳性浸润细胞减少, Ⅰ/Ⅲ型胶原纤维比值下降(F=41.11, P<0.01);血液中调节性T细胞(CD4+CD25+Foxp3+)/效应T细胞(CD4+CD25+)比值增高(F=21.64, P<0.01), 且外周血和脾脏中Tfr(CD4+CXCR5+Foxp3+)/Tfh(CD4+CXCR5+)比值均升高(F=38.95, P<0.01;F=12.90, P<0.01)。结论 IL-7受体α抗体可能通过升高调节性T细胞比例、Tfr/Tfh比值, 降低自身抗体如抗双链DNA抗体生成, 减少炎性因子生成, 从而减轻MRL/lpr狼疮小鼠的免疫炎症和肾脏损害。

Objective To investigate the effect of interleukin(IL)-7 receptorα(IL-7Rα)antibody on the immune inflammation and renal injury in MRL/lpr lupus mice.Methods Fifteen 3-4-week-old female MRL/lpr lupus mice(specific pathogen free)weighing 15-16 g were bred to 14-week-old and randomly divided into three groups:IL-7Rαantibody intervention group,isotype antibody(positive control)group and normal saline(negative control)group.The mice in the threc groups were intraperitoneally injected with IL-7Rαantibody,isotype antibody and normal saline respectively,with 100μg three times a week for 4 weeks.At the age of 18-week old,the mice were sacrificed.Twenty-four-hour urinary protein was detected by Coomassie brilliant blue method,serum creatinine was detected by peroxidase method,and the expression of autoantibody(anti-double strand DNA antibody)and inflammatory factors such as tumor necrosis factor-α(TNF-α),interferon-γ(IFN-γ)and IL-21 was detected by enzyme-linked immunosorbent assay method.Renal pathology was detected by PAS and Sirius red staining,and CD3 and F4/80 in renal tissues were detected by immunohistochemistry method.Regulatory T cells,follicullar helper T cells(Tfh)and follicular regulatory T cells(Tfr)were detected by flow cytometry.Results The 24-hour urinary protein,serum creatinine,serum anti-double strand DNA antibody and serum IFN-γand IL-21 in the IL-7Rαantibody intervention group were significantly lower than those in the control groups(all P<0.01).However,there was no significant difference in serum TNF-αamong the three groups(F=0.39,P>0.05).The positive infiltrating cells of CD3 and F4/F80,and the ratio of typeⅠ/Ⅲcollagen fibers(F=41.11,P<0.01)of renal tissues in the IL-7Rαantibody intervention group were lower than those in the other two groups.Compared with the control groups,the ratio of regulatory T cells(CD4+CD25+Foxp3+)/effector T cells(CD4+CD25+)in blood of IL-7Rαantibody intervention group increased(F=21.64,P<0.01),while the ratio of Tfr(CD4+CXCR5+Foxp3+)/Tfh(CD4+CXCR5+)in peripheral blood and spleen increased(F=38.95,P<0.01;F=12.90,P<0.01).Conclusion IL-7Rαantibody can reduce the production of autoantibodies such as anti-double strand DNA antibody and inflammatory factors by increasing the ratio of regulatory T cells and Tfr/Tfh,thus alleviating immune inflammation and renal damage in MRL/lpr lupus mice.