Abstract: Objective　To explore the mechanism of the CCAAT-enhancer-binding protein-beta (C/EBPβ) /serine/threonine kinase 1 (pim-1) /NOD-like receptor thermoprotein domain-associated protein 3 (NLRP3) axis mediating renal podocyte injury in mice. Methods　After in vitro culturing and transfecting, mouse renal podocytes were divided into the Control group, the siRNA-NC group (podocytes were transfected with siRNA-NC), the siC/EBPβ group (podocytes were transfected with C/EBPβ lentivirus), the Vector-NC group (podocytes were transfected with empty vector) and the pim-1-OE group (podocytes were transfected with pim-1 overexpressed lentivirus). After podocytes were stimulated by lipopolysaccharide (LPS) and adenosine triphosphate (ATP), podocytes were divided into the LPS+ATP group, the LPS+ATP+siRNA-NC group, the LPS+ATP+siC/EBPβ group, the LPS+ATP+siC/EBPβ+Vector-NC group and the LPS+ATP+siC/EBPβ+pim-1-OE group. C/EBPβ and pim-1 mRNA were detected by real-time quantitative PCR (qPCR). The levels of C/EBPβ, pim-1, NLRP3, p20 cysteine protease (Caspase)-1, Gasdermin D (GSDMD) and p17 interleukin (IL) -1β were detected by Western blot assay. The levels of IL-1β and IL-6 were detected by enzyme-linked immunosorbent assay (ELISA). Chromatin immunoprecipitation assay (chip) and dual luciferase reporter assay were used to detect the binding of C/EBPβ to pim-1 gene promoter. Results　Compared with the Control group and the siRNA-NC group, the level of C/EBPβ and pim-1mRNA were significantly decreased in the siC/EBPβ group (P＜0.01). Compared with the Control group, the levels of NLRP3, p20Caspase-1, p17IL-1β protein and IL-6 were significantly increased in the LPS+ATP group (P＜0.01). Compared with the LPS+ATP+siRNA-NC group, the levels of NLRP3, p20Caspase-1, p17IL-1β protein and IL-6 were significantly decreased in the LPS+ATP+siC/EBPβ group (P＜0.01). Chip assay and luciferase reporter assays showed that C/EBPβ could bind to pim-1 gene promoter. Compared with the Control group and the Vector-NC group, the level of pim-1mRNA was significantly increased in the pim-1-OE group (P＜0.05). Compared with the LPS+ATP+siC/EBPβ+Vector-NC group, the levels of NLRP3, p20Caspase-1, GSDMD, p17IL-1β protein and IL-6 were significantly increased in the LPS+ATP+siC/EBPβ+pim-1-OE group (P＜0.05). Conclusion　The C/EBPβ/pim-1/NLRP3 axis may be involved in podocyte injury, providing a potential therapeutic target for patients with lupus nephritis.

Key words: lupus nephritis, podocytes, NLR family, pyrin domain-containing 3, CCAAT-enhancer-binding protein-beta, proto-oncogene proteins c-pim-1