OBJECTIVE To investigate the mechanism of nicotinamide mononucleotide (NMN) on inflammation and fibrosis between endogenous nicotinamide phosphoribosyltransferase (NAMPT) and bone morphogenetic protein 7 (BMP-7) in diabetic glomerular cells.METHODS ① In vivo,spontaneous diabetic C57/BL6 mice and wild C57/BL6 mice were divided into two groups.When blood glucose was above (34.2±1.9) mmol· L-1,renal histology of diabetic mice became obvious.The protein expressions of Nampt and nuclear transcription factors-kappa B p65 (NF-κB p65),silent mating type information regulation 2 homolog 1 (SIRT1) and BMP7 were analyzed by lengths of immunofluorescence.② In vitro,rats' glomerular cells HBZY-1 were incubated with glucose 200 mmol· L-1 for different lengths of time (0,24,48 and 72 h) and at different concentrations of NMN (0,50,100 and 200 iμmol· L-1).The protein levels of Nampt and BMP7 were detected by Western blotting and the protein expressions of NF-κB p65 and α-SMA were measured by immunofluorescence assay.The protein levels of Nampt,BMP7 and NF-κB p65 were detected by Western blotting after HBZY-1 cells were treated with NMN 100 μmol· L-1 and FK866 10 μmol· L-1 for 24 h.RESULTS ① In vivo,the glomeruli of diabetic C57/BL6 mice showed obvious atrophy.Fluorescence intensity of Nampt was increased (P＜0.05),but that of BMP7 and SIRT1 in renal glomeruli cells was decreased compared with the wild type (P＜0.01).② In vitro,HBZY-1 cells were cultured in glucose 200 mmol· L-1 for 48 and 72 h.The protein expression of NAMPT was increased,but that of BMP7 was decreased (P＜0.05,P＜0.01).Expressions of NF-κB p65 and α-SMA were increased (P＜0.01) by immunofluorescence.The expression of BMP7 was increased after treatment with glucose 200 mmol· L-1,followed by NMN 50,100 and 200 μmol · L-1 for 24 h (P＜0.01).The expressions of NAMPT and NF-κB p65 were decreased (P＜0.01).The expressions of Nampt and NF-κB p65 in glucose 5.6 mmol· L1 +FK866 and glucose 5.6 mmol· L-1+ NMN groups were increased (P＜0.01),but the expression of BMP7 did not change.CONCLUSION Upregulation of endogenous Nampt obviously intervenes in BMP7 expression in the process of glomerular inflammatory fibrosis in severe diabetes.NMN can affect the protein expression of BMP7 via a special Nampt signaling pathway.

Objective:To investigate the regulation effect of endogenous nicotinamide phosphoribosyl transferase (Nampt) on the Vimentin expression of glomerular cells in high concentration glucose,and to clarify the mechanism of formation of diabetic kidney inflammation fibrosis.Methods:The C57/BL6 diabetic mice were selected and the kidney tissues were collected,and the wild C57/L86 mice were used as control group;the pathological section and tissue fluorescence staining were performed.The expression and location of endogenous Nampt and Vimentin in the glomerular cells were detected by immuno-focused technology.The HBZY-1 cells were randomly divided into 4 groups:low concentration of glucose (LG,0.56 mmol · L-1) control group,high concentration glucose (HG,200 mmol · L-1) group,HG +-FK866 group and HG+nicotinamide mononucleotide (NMN) group.In HG group,the cells were treated with FK866 (10 μmol · L-1) and NMN (1 mmol · L-1) for 24 h after cultured with HG for 5 d.The expression levels of Nampt,Vimentin,nuclear factor-kappa B p65 (NF-κBp65) and sirtuin type 1 (Sirt1) were detected by immunofluorescence and Western blotting methods.The expression levels of Nampt and Vimentin were detected by RT-PCR and Western blotting methods.Results:The shape and size of glomerulus had obvious atrophy of the mice in severe diabetic group compared with normal C57/BL6 mice group.The expression level of Vimentin in glomerular cells was increased with the increasing of endogenous Nampt (P＜0.01).When the HBZY-1 cells were cultured in HG condition,the exprssion levels of Nampt,Vimentin and NF-kB p65 were obviously increased while the Sirt1 expression levels was significantly decreased compared with control group (P＜ 0.01).The expression levels of Nampt,Vimentin and NF-κB p65 in glomerular cells in HG+FK866 HG+ NMN groups were singnificartyly decreased compared with control group (P＜0.01).Conclusion:The endogenous Nampt over-expression in glomerular cells can enhance the expression of Vimentin under high concentration of glucose stress through NF-κBp65 and Sirt1 signal pathway.