[C/EBPβ mediates expressions of downstream inflammatory factors of the tumor necrosis factor- α signaling pathway in renal tubular epithelial cells with NPHP1 knockdown].

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 ( NPHP1 KD ) 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 NPHP1 KD HK2 cells, and the changes in the expressions of TNF- α , p38, and C/EBPβ and the inflammatory factors were examined.

RESULTS: NPHP1 KD HK2 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 NPHP1 KD HK2 cells, and C/EBPβ may serve as a key transcription factor to mediate these changes.