Paecilomyces cicadae-fermented Radix astragali activates podocyte autophagy by attenuating PI3K/AKT/mTOR pathways to protect against diabetic nephropathy in mice

Radix astragali, a medicinal material for tonifying Chinese Qi, has widely been used for the treatment of Kidney disease in China and East Asia, especially in reducing the apoptosis of glomerular podocytes. Paecilomyces Cicadidae is a medicinal and edible fungus. In recent years, the application of traditional Chinese medicine (TCM) in solid-state fermentation of edible and medicinal fungi has become a hot issue. Fermentation is a special method to change the properties of TCM. Therefore, the potential roles and molecular mechanisms on podocytes of solid-state fermentation products of Radix astragali and Paecilomyces cicadidae (RPF) in diabetic nephropathy (DN) were studied. In vivo, the effect of RPF and Radix astragali on DN in mice was evaluated by detecting the biochemical indexes of blood and urine, renal function and podocyte integrity. In vitro, the expression of podocyte marker protein, autophagy marker protein and PI3K/AKT/mTOR signaling pathway protein were detected by Western blotting using a high glucose-induced podocyte injury model. The results showed that RPF had a significant alleviative effect on DN mice. RPF can significantly reduce urine protein, serum creatinine, and blood nitrogen urea in DN mice. Morphological analysis showed that RPF could improve kidney structure of DN and reduce the apoptosis of podocytes, and the effect was better than Radix astragali. In vitro results indicated that RPF could enhance autophagy and protect podocytes by inhibiting the PI3K/AKT/mTOR signaling pathway. In summary, RPF has better effect on delaying the development of DN than Radix astragali. RPF enhances autophagy in podocytes and delays DN probably by inhibiting the PI3K/AKT/mTOR signaling pathway.