Wang Hongtian, Zheng Chunxia, Xu Xiaodong, Zhao Yue, Lu Yinghui, Liu Zhihong
Division of Nephrology, Jinling Hospital, Southern Medical University, Nanjing, China.
National Clinical Research Center of Kidney Diseases, Jinling Hospital, Nanjing University School of Medicine, Nanjing, China.
Nephrology (Carlton). 2018 May;23(5):418-429. doi: 10.1111/nep.13046.
Fibrinogen (Fg) is reported to participate in inflammation through Toll-like receptor 4 (TLR4). However, it remains unknown whether Fg might induce podocyte damage through TLR4 and be related to disease activity in patients with focal segmental glomerulosclerosis (FSGS).
We observed Fg-induced alterations in actin and apoptosis in cultured human podocytes transfected with or without TLR4 siRNA. Expression of TLR4, phospho-p38 MAPK and phospho-NF-κB p65 was evaluated by quantitative reverse transcription polymerase chain reaction (qRT-PCR) or western blotting, and we analysed urinary Fg levels in adriamycin-treated mice and double immunofluorescence staining for TLR4, Fg and podocin. Urinary Fg changes were also analyzed in FSGS patients under prednisone treatment.
First, Fg dose-dependently induced actin damage and apoptosis in cultured human podocytes, with an Fg-induced increase in TLR4 expression, and TLR4 siRNA transfection prevented these effects. TLR4 knockdown inhibited activation of p38 MAPK and NF-κB p65 in podocytes. Elevated urinary Fg levels were positively correlated with albuminuria in adriamycin-treated mice, in which Fg and TLR4 colocalized and exhibited increased expression in podocytes. Additionally, elevated urinary Fg levels were positively correlated with 24-h proteinuria and foot process width in FSGS patients. Urinary Fg levels were significantly decreased in patients with complete remission but not in those without remission.
Fg induced podocytes injury via the TLR4-p38 MAPK-NF-κB p65 pathway. In FSGS patients, urinary Fg levels reflect therapeutic response to prednisone and disease activity.
据报道，纤维蛋白原（Fg）通过Toll样受体4（TLR4）参与炎症反应。然而，Fg是否可能通过TLR4诱导足细胞损伤并与局灶节段性肾小球硬化（FSGS）患者的疾病活动相关仍不清楚。
我们观察了Fg对转染或未转染TLR4小干扰RNA（siRNA）的培养人足细胞中肌动蛋白和细胞凋亡的影响。通过定量逆转录聚合酶链反应（qRT-PCR）或蛋白质免疫印迹法评估TLR4、磷酸化p38丝裂原活化蛋白激酶（p38 MAPK）和磷酸化核因子κB p65（NF-κB p65）的表达，并分析阿霉素处理小鼠的尿Fg水平以及对TLR4、Fg和足突蛋白进行双重免疫荧光染色。还分析了接受泼尼松治疗的FSGS患者的尿Fg变化。
首先，Fg剂量依赖性地诱导培养的人足细胞中肌动蛋白损伤和细胞凋亡，Fg诱导TLR4表达增加，而转染TLR4 siRNA可阻止这些效应。敲低TLR4可抑制足细胞中p38 MAPK和NF-κB p65的激活。阿霉素处理的小鼠尿Fg水平升高与蛋白尿呈正相关，其中Fg和TLR4共定位且在足细胞中表达增加。此外，FSGS患者尿Fg水平升高与24小时蛋白尿和足突宽度呈正相关。完全缓解的患者尿Fg水平显著降低，而未缓解的患者则未降低。
Fg通过TLR4-p38 MAPK-NF-κB p65途径诱导足细胞损伤。在FSGS患者中，尿Fg水平反映了对泼尼松的治疗反应和疾病活动度。
