Grifola frondosa Polysaccharide Ameliorates Early Diabetic Nephropathy by Suppressing the TLR4/NF-κB Pathway

Grifola frondosa is a medicinal macro-fungus with a wide range of biological activities. Polysaccharides from Grifola frondosa (PGF) play a positive role in regulating blood glucose and alleviating kidney injury. Here, we investigated the exact mechanism of action by which PGF ameliorates diabetic nephropathy. Our results showed that PGF effectively improved glucose tolerance and insulin sensitivity in streptozocin (STZ)-induced DN mice. Additionally, administration of PGF also ameliorated renal function and inflammatory response in STZ-induced DN mice. Consistent with the in vitro results, the high glucose-induced inflammatory response and apoptosis of renal tubular epithelial cells were decreased by PGF treatment. Furthermore, PGF not only suppressed the expression of TLR4, but also more effectively protected the kidney and reduced the inflammatory response when TLR4 was inhibited. All these data revealed that PGF alleviates diabetic nephropathy by blocking the TLR4/NF-κB pathway.