Paeoniflorin prevents TLR2/4-mediated inflammation in type 2 diabetic nephropathy

Paeoniflorin is an effective Chinese traditional medicine with anti-inflammatory and immune-regulatory effects. The aim of this study was to investigate the underlying renoprotective mechanism of Paeoniflorin. In vivo, db/db mice were intraperitoneally injected with Paeoniflorin at a dose of 15, 30, or 60 mg/kg respectively. The immunostaining of TLR2, TLR4, CD68, NF-kB p65 and the mRNA level of inflammatory factors, together with the protein expression of TLR2/4 signaling were evaluated. Our data demonstrated that Paeoniflorin could decrease the urinary albumin excretion rate and inhibit macrophage infiltration and activation through blockage of the TLR2/4 signaling pathway compared with the db/db group in vivo. In vitro, RAW264.7 cells were categorized into control, bovin serum albumin (BSA)-stimulated, advanced glycation end products (AGEs)-stimulated, Paeoniflorin intervention and oxidized phospholipid (OxPAPC)-inhibited groups. The cell viability, the optimal stimulated time and concentration were measured as well as the TLR2/4 signaling activation determined by RT-PCR, Western blot and ELISA. Our data demonstrated that Paeoniflorin reduced the AGEs-induced TLR2/4 activation and inflammatory responses, which was consistent with the TLR2/4 inhibitor group. These findings indicate that Paeoniflorin prevents macrophage activation via inhibition of TLR2/4 signaling expression in type 2 diabetic nephropathy.