Objective: To explore the activation of tumor necrosis factor-α (TNF-α) signaling pathway and the expressions of the associated inflammatory factors in NPHP1-defective renal tubular epithelial cells.
Methods: A human proximal renal tubular cell (HK2) model of lentivirus-mediated NPHP1 knockdown (NPHP1KD) was constructed, and the expressions of TNF-α, p38, and C/EBPβ and the inflammatory factors CXCL5, CCL20, IL-1β, IL-6 and MCP-1 were detected using RT-qPCR, Western blotting or enzyme-linked immunosorbent assay. A small interfering RNA (siRNA) was transfected in wild-type and NPHP1KDHK2 cells, and the changes in the expressions of TNF-α, p38, and C/EBPβ and the inflammatory factors were examined.
Results: NPHP1KDHK2 cells showed significantly increased mRNA expressions of TNF-α, C/EBPβ, CXCL5, IL-1β, and IL-6 (P < 0.05), protein expressions of phospho-p38 and C/EBPβ (P < 0.05), and IL-6 level in the culture supernatant (P < 0.05), and these changes were significantly blocked by transfection of cells with siRNA-C/EBPβ (P < 0.05).
Conclusion: TNF-α signaling pathway is activated and its associated inflammatory factors are upregulated in NPHP1KDHK2 cells, and C/EBPβ may serve as a key transcription factor to mediate these changes.
目的: 探讨NPHP1基因缺陷肾小管上皮细胞TNF-α信号通路激活及其调控的炎症因子表达。
方法: 使用重组慢病毒LV-NPHP1-RNAi构建敲低NPHP1表达的人近端肾小管细胞株（HK2）细胞（NPHP1KD HK2）。通过实时荧光定量PCR、Western blot、酶联免疫吸附实验法检测各细胞株TNF-α表达、p38和C/EBPβ激活状态及其调控炎症因子CXCL5、CCL20、IL-1β、IL-6、MCP-1等表达情况。通过构建siRNA敲低野生型和NPHP1KD HK2细胞C/EBPβ表达，观察上述指标变化。
结果: 敲低NPHP1表达后，NPHP1KD HK2细胞TNF-α、C/EBPβ、CXCL5、IL-1β和IL-6的mRNA表达量增加（P＜0.05）；Western blotting结果显示，phospho-p38、C/EBPβ表达上调（P＜0.05）；培养液上清IL-6水平增加（P＜0.05）。使用siRNA敲低C/EBPβ表达后，NPHP1KDHK2细胞CSF2、CCL20、IL-1β和IL-6的mRNA表达水平下调（P＜0.05）；Western blot显示phospho-p38表达下调（P＜0.05）；培养液上清IL-6水平下降（P＜0.001）。
结论: NPHP1基因缺陷的NPHP1KDHK2细胞中TNF-α信号通路被激活，其调控的下游印证因子表达上调。C/EBPβ可能是介导NPHP1KDHK2细胞TNF-α信号通路相关炎症因子表达的关键转录因子。
Keywords: C/EBPβ; NPHP1; inflammatory factor; nephronophthisis; tumor necrosis factor-α.