The Effect And Mechanical Study Of Curcumin On Lipid-Induced Renal Injury

Gomerular sclerosis is the final common pathological feature to endstage renal disease, and disorder of lipid metabosis is the one of the independent pathogenic factors in the progress of the gomerular sclerosis. Recent study has found that inflammation and oxidative stress are important in the lipid nephrotoxicity. The signal pathway of p38 mitogen-activated protein kinases is the important to regulate the cell proliferation and differentiation under stress in many kinds of cells. Modern medicine show that curcumin have the effection of anti-inflammation, anti-oxidation, decrease of lipid, inhibition of cell proliferation and anti-fibrosis, then we wandered whether curcumin relieved renal injury induced by lipid, what is the possible mechanism, whether p38 mitogen-activated protein kinases involve in the progress. The study is to explore the effect of curcumin to lipid-induced renal injury and the possible signal pathway by the cellular experiment and the animal experiment, in order to provide the experimental basement on the clinical application of curcumin.Part One The Signal Pathway of p38 Mitogen-activated ProteinKinases Involved in the Proliferation of Rat Mesangial Cells andMatrix Induced by Low-density LipoproteinObjective To observe the proliferation of rat mesangial cells, the expression of matrix metalloproteinases-2 (MMP-2) and the activity of p38 MAPK induced by low-density lipoprotein(LDL) or LDL plus SB203580(the special inhibitor of p38 MAPK), and to explore whether p38 MAPK involve in the damage of mesangial cell induced by LDL. Methods Cultured rat mesangial cells were performed with LDL of different concentration or LDL of different concentration plus SB203580 in vitro. Cell viability was measured by MTT assay. The expression of MMP-2 mRNA and protein were measured by RT-PCR and Western Blot. The activity of p38 MAPK was measured by Western Blot. Results The proliferation of mesangial cells were promoted by LDL of the concentration from 3.125 to 100μ g/ml (P<0.05), when the LDL concentration was from 0 to 50μ g/ml, the proliferation of mesangial cells was correlated with LDL concentration (r=0.865, P<0.05) , the proliferation was inhibited when the cells was pretreated with SB203580 (P<0.05 ) . The expression of MMP-2 mRNA were downregulated by LDL of the concentration from 12.5 to 100μ g/ml (P<0.05) , SB203580 upregulated the expression of MMP-2 mRNA induced by LDL (P<0.05) . The expression of MMP-2 protein were downregulated by LDL of the concentration from 25 to 100μ g/ml (P<0.05) , SB203580 upregulated the expression of MMP-2 protein induced by LDL (P<0.05) . P38 MAPK were activated by LDL of the concentration from 12.5 to 100μ g/ml (P<0.05) , SB203580 inhibited the activation (P<0.05) . Conclusions LDL induce the proliferation of mesangial cells and matrix, the possible mechanism involve in the p38 MAPK.Part Two The Downregulation of p38 MAPK Involved in the Inhibition of LDL-induced Proliferation of Rat Mesangial Cells and Matrix by CurcuminObjective To observe the inhibition of LDL-induced proliferation of rat mesangial cells and matrix by curcumin, and the signal transduction of cyclooxygenase-2(COX-2), ROS and p38 MAPK in this progress. Methods Cultured rat mesangial cells were performed with 25μg/ml LDL and different concentration of curcumin in vitro. Cell viability was measured by MTT assay; intracellular ROS production was visualized using a fluorescent dye, the expression of COX-2/MMP-2 mRNA and protein was measured by RT-PCR and Western Blot, the activity of p38 MAPK was measured by Western Blot. Results The proliferation of mesangial cells induced by 25μg/ml LDL was inhibited and the expression of MMP-2 mRNA was upregulated by curcumin of the concentration from 6.25 to 25μmol/l (P<0.05) , the expression of MMP-2 protein (P<0.05) , COX-2 mRNA and protein was upregulated (P<0.05) , the production of ROS was inhibited and the activity of p38 MAPK was downregulated by curcumin of the concentration from 12.5 to 25μmol/l (P<0.05) . Conclusions The proliferation of mesangial cells and the downregulation of expression of MMP-2 induced by LDL are inhibited by 12.5 to 25μmol/l curcumin, and the possible signal transduct pathway involve in the inhibition of the expression of COX-2 and the production of ROS, then inhibite the activity of p38 MAPK by curcumin.Part Three The Effect and Mechanical Study of Curcumin on Adriamycin Nephropathy in RatsObjective To observe the effect of curcumin on lipid metabolism, renal pathology, the expression of MMP-2, the expression of COX-2, and the activity of p38 MAPK in the adriamycin-induced nephritic rats, to explore the possible mechanism and the signal pathway on the relief of adriamycin nephropathy by curcumin. Methods Adriamycin-induced nephritic rat models were established by a single injection of adriamycin via the tail vein, the rats in the curcumin treatment group were given curcumin (100mg·kg^-1·d^-1) by intragastric administration. Immunohistochemical staining, RT-PCR and Western Blot were used to examine the expression of MMP-2 and COX-2. Western Blot was used to examine the activity of p38 MAPK. Results (1) in adriamycin-induced nephritic rats,urinary protein (P<0.05) and the level of cholesterol (P<0.05) , triglyceride (P<0.05) and LDL (P<0.05) were decreased and the serum albumin (P<0.05) increased by curcumin. (2) curcumin minificated the messangial district in the adriamycin-induced nephritic rats (P<0.05) . (3)curcumin upregulated the expression of MMP-2 in the adriamycin-induced nephritic rats(P<0.05). (4) curcumin downregulated the expression of COX-2 in the adriamycin-induced nephritic rats (P<0.05) .(5) curcumin inhibited the activity of p38 MAPK in the adriamycin-induced nephritic rats (P<0.05) . Conclusions Curcumin decrease the urinary protein and reduced the damage of the renal histology of the adriamycin-induced nephritic rats, the possible mechanism is that the relief of the lipid metabosis, the low expression of COX-2 inhibit the the proliferation of the messangial cells and matrix by the p38 MAPK pathway.