Folic Acid Protects Against Kidney Damage in Mice with Diabetic Nephropathy by Inhibiting M1 Macrophage Polarization via Nuclear Factor-k-gene Binding Pathway.

Kidney damage is one of the most common complications of diabetes, and inflammation caused by macrophage infiltration plays an important role. Folic acid (FA), a water-soluble vitamin, was previously found to affect inflammation by regulating macrophage polarization. In our study, we aimed to investigate the effect of FA on renal injury in mice with diabetic nephropathy (DN). We found that FA treatment ameliorated diabetic metabolic parameters in mice with DN, including reducing 24-hour food consumption, 24-hour urine volume and 24-hour water intake and increasing body weight and serum insulin. Of note, FA treatment improved renal functional and structural damage in mice with DN. In addition, FA treatment significantly reduced the number of renal infiltrating M1 macrophages, inflammatory cytokine FA stimulation significantly reduced the increase in F4/80+CD86+ cell ratio, inflammatory factor content and p-p65/p65 protein expression induced by high glucose exposure in RAW264.7 cells. All in all, our results indicated that FA protects against kidney damage in mice with DN by inhibiting M1 macrophage polarization, and its mechanism may be related to the inhibition of nuclear factor-k-gene binding (NF-kB) signaling pathway.