To investigate whether the JAK2/STAT3 signaling pathway is involved in the epithelial-mesenchymal transition (EMT) of peritoneal mesothelial cells in uremic peritoneal dialysis (PD) rats.

A total of 48 male Sprague-Dawley (SD) rats were randomly separated into six groups: normal control group (NC group, n=8), sham group (n=8), uremic group (n=8), PD group (n=8), S3I-201 control group (n=8) and S3I-201 group (n=8). Uremic model generated by 5/6 nephrectomy surgery in rats was established. The rats of PD group, S3I-201 control group and S3I-201 group received daily infusion of 4.25% glucose-based peritoneal dialysate fluid (3 ml/100 g) from PD catheters for 28 days. Rats of S3I-201 group were injected with STAT3 inhibitor S3I-201 (2.5 mg/kg) solution from the catheters every other day; the same dose of the solvent of S3I-201 was simultaneously given to S3I-201 control group rats. After PD for 28 days, peritoneal function, pathologic changes, and microvessel density (MVD) were evaluated. Creatinine, urea nitrogen and interleukin-6 (IL-6) concentration in blood and dialysate, and protein and mRNA levels of phospho-JAK2 (p-JAK2), phospho-STAT3 (p-STAT3), E-cadherin, alpha-smooth muscle actin (α-SMA) and vascular endothelial growth factor (VEGF) in peritoneum were determined.

Uremia and peritoneal dialysate could aggravate the peritoneal function and elevate peritoneal thickness and MVD. They could also increased the concentration of IL-6 in blood and dialysate and the expression levels of α-SMA, VEGF, p-JAK2 and p-STAT3 in peritoneum, while lowering E-cadherin expression in peritoneum. These manifestations were even more remarkable in PD group compared to those in uremic group. There was no statistical difference between the S3I-201 control group and the PD group as regards all the index (all P>0.05). Compared with the S3I-201 control group, the rats treated with S3I-201 showed better peritoneal function. S3I-201 could reduce peritoneal thickness (P<0.05), MVD (P<0.05), the concentration of IL-6 in blood and dialysate, the mRNA and protein expression of α-SMA, VEGF, p-JAK2 and p-STAT3 (all P<0.05), while enhance the mRNA and protein expression of E-cadherin (all P<0.05).

After STAT3 is inhibited, the peritoneal thickness, MVD and IL-6 concentration in PD rats are decreased, and EMT is also inhibited, while peritoneal function is improved. The JAK2/STAT3 signaling pathway may thus be involved in the process of EMT of peritoneum in uremic peritoneal dialysis rats by regulating the expression of IL-6.

Peritoneal dialysis; Epithelial-mesenchymal transition; Fibrosis; JAK2/STAT3 signaling pathway; Interleukin-6