Objective To establish the model mice with focal segmental glomerulosclerosis (FSGS) by precise 5/6 nephrectomy, and to explore the pathogenesis of Januskinase 2/signal transducer and activator of transcription 3 (JAK2/STAT3) signaling pathway in model mice with FSGS.

Methods A total of 60 male C57BL/6 mice aged 6 weeks were selected and randomly divided into control group (n=30) and FSGS group (n=30). The mice in the FSGS group received precise 5/6 nephrectomy, and the volume of nephrectomy was calculated by volume formula. The control group was a sham operation group, the bilateral kidneys of mice were exposed only, and the adipose tissue around the kidney was stripped before restoration and suturing. The 24 h urinary protein, serum creatinine and urea nitrogen were compared between the two groups; hematoxylin-eosin (HE) staining was used to observe the pathological change of kidney tissue; the target genes of JAK2/STAT3 signal pathway in renal tissues were detected by real-time fluorescent quantitative PCR (RT-qPCR); the target proteins of JAK2/STAT3 signal pathway were detected by western blot; the enzyme-linked immunosorbent assay (ELISA) was used to detect the levels of inflammatory factors and fibrosis factors in the downstream of JAK2/STAT3 signal pathway.

Results During the modeling process, one mouse in the FSGS group died of anesthesia and was excluded; the success rate of establishing model mice with FSGS by precise 5/6 nephrectomy was 89.7% (26/29). Compared with the control group, the 24 h urine protein, blood creatinine and urea nitrogen levels in the mice of the FSGS group were significantly higher (P < 0.01). In the FSGS group, HE staining showed a large number of apoptosis and necrosis of renal tubular epithelial cells, expansion of renal vesicles, compensatory glomerular hypertrophy and focal sclerosis, proliferation of mesangial cells and mesangial matrix, and infiltration of inflammatory cells. At 10 weeks after operation, the expression levels of JAK2 mRNA and STAT3 mRNA, the protein expression levels of phosphorylated Janus kinase 2 (p-JAK2), JAK2, phosphorylated signal transducer and activator of transcription 3 (p-STAT3) and STAT3, and levels of interleukin-6 (IL-6), monocyte chemoattractant protein-1 (MCP-1), α-smooth muscle actin (α-SMA) and transforming growth factor-β₁ (TGF-β₁) were increased significantly (P < 0.01).

Conclusion Precise 5/6 nephrectomy is helpful in successfully establishing model mice with FSGS, and the activation of JAK2/STAT3 signaling pathway can participate in the occurrence and development of FSGS by promoting inflammatory response, renal fibrosis and other ways.