Paeoniflorin ameliorates Adriamycin-induced nephrotic syndrome through the PPARγ/ANGPTL4 pathway in vivo and vitro

Paeoniflorin (PF), an effective composition that is extracted from Radix Paeoniae Alba, plays a role in protecting against various kidney diseases. However, the mechanism of PF on nephrotic syndrome (NS) remains unclear. The aim of this study was to investigate the protective role of PF on Adriamycin (ADR)-induced NS in vivo and vitro as well as its potential mechanism. In animal study, PF significantly decreased the levels of 24-h urine protein, blood urea nitrogen, serum creatinine, total cholesterol and triglycerides in NS rats, but increased the total protein and albumin levels. Hematoxylin-eosin (HE) staining revealed that the kidney lesion was resolved upon PF treatment. After treatment with PF, the morphology and number of podocytes in renal tissue were restored to normal. PF increased expression of synaptopodin and decreased expression of desmin, demonstrating a protective effect in podocyte injury. Further studies revealed that PF upregulated Peroxisome proliferator-activated receptor gamma (PPAR gamma) and restrained Angiopointin-like 4 (ANGPTL4) in kidney tissue. In vitro study, PF reduced Caspase3 and Bax and increased Bcl-2, indicating that the apoptosis rate of podocytes induced by ADR was reduced by PF. Furthermore, PF ameliorated podocyte injury by upregulating synaptopodin and reducing desmin. In accordance with animal study, PF downregulated ANGPTL4 by activating PPAR gamma. However, the therapeutic effects of PF were reversed by GW9662 (PPAR gamma inhibitor), likely by suppressing ANGPTL4 degradation. In general, these results demonstrate that PF has a good therapeutic effect on NS by activating PPAR gamma and subsequently inhibiting ANGPTL4.