Intervention Mechanism of Niao Du Kang Mixture on the EMT Process of Peritoneal Fibrosis Based on the Wnt/β-Catenin Signaling Pathway

Abstract

Ethnopharmacological Relevance. The Niao Du Kang mixture has been traditionally used in treating chronic kidney disease, and previous studies have shown that this herbal formula can delay the progression of peritoneal fibrosis (PF) in peritoneal dialysis. However, further study is necessary to ascertain the specific mechanism and provide additional scientific basis for the clinical treatment of PF. Aim of the Study. The purpose of this study was to investigate whether the intervention mechanism of the Niao Du Kang mixture on the peritoneal fibrosis epithelial-mesenchymal transition (EMT) is related to the Wnt/β-catenin signaling pathway. Methods. Quantification of 24-hour urine protein (24 h-Upro) and serum creatinine (Scr) levels was performed. The protein and mRNA expression levels of E-cadherin, α-SMA, collagen I, β-catenin, Wnt-1, and LEF-1 in peritoneal tissue were measured. In addition, the pathological morphology and ultrastructure of peritoneum were observed. Results. After 5/6 nephrectomy + high glucose peritoneal dialysate + lipopolysaccharide (LPS) treatment, the Scr and 24 h-Upro of rats increased compared with normal rats, and the peritoneal tissue was damaged and thickened, showing fibrotic changes. Compared with the model group, the Scr and 24 h-Upro levels and the levels of E-cadherin, α-SMA, Wnt-1, collagen I, and LEF-1 protein expression in each Niao Du Kang mixture dosage group decreased. The protein expression of β-catenin and the mRNA expression of E-cadherin, α-SMA, Wnt-1, collagen I, β-catenin, and LEF-1 decreased in the high and medium Niao Du Kang mixture dose groups. Hematoxylin and eosin staining showed that the peritoneum of the rats was not only thicker in the model group than in the sham operation group ( $P<0.01$ ) but also accompanied by apparent inflammatory cell infiltration, tissue edema, and fibrosis. Compared with the model group, all the Niao Du Kang mixture groups demonstrated various degrees of mitigation in peritoneal thickness and fibrosis ( $P<0.01$ ). The strongest effect was observed in the medium-dose group. Transmission electron microscopy showed that the degree of injury of the peritoneal mesothelial cells was ranked as follows: model group > positive drug group > Niao Du Kang mixture high-dose group. Conclusions. The Niao Du Kang mixture may effectively decrease the peritoneal thickness and fibrosis degree through its effect on the Wnt/β-catenin signaling pathway involved in EMT. The present study provides data that assist in elucidating the potential function of the Niao Du Kang mixture in treating or preventing PF.