BACKGROUNDThe renoprotective mechanisms of adenosine monophosphate (AMP)-activated protein kinase (AMPK) agonist - metformin have not been stated clearly. We hypothesized that metformin may ameliorate inflammation via AMPK interaction with critical inflammatory cytokines. The aim of this study was to observe the effects of metformin on expression of nuclear factor-κB (NF-κB), monocyte chemoattractant protein-1 (MCP-1), intercellular adhesion molecule-1 (ICAM-1) and transforming growth factor-beta 1 (TGF-β1) induced by high glucose (HG) in cultured rat glomerular mesangial cells (MCs).

METHODSMCs were cultured in the medium with normal concentration glucose (group NG, 5.6 mmol/L), high concentration glucose (group HG, 25 mmol/L) and different concentrations of metformin (group M1, M2, M3). After 48-hour exposure, the supernatants and MCs were collected. The expression of NF-κB, MCP-1, ICAM-1, and TGF-β1 mRNA was analyzed by real time polymerase chain reaction. Western blotting was used to detect the expression of AMPK, phospho-Thr-172 AMPK (p-AMPK), NF-κB p65, MCP-1, ICAM-1, and TGF-β1 protein.

RESULTSAfter stimulated by HG, the expression of NF-κB, MCP-1, ICAM-1, TGF-β1 mRNA and protein of MCs in group HG increased significantly compared with group NG (P < 0.05). Both genes and protein expression of NF-κB, MCP-1, ICAM-1, TGF-β1 of MCs induced by high glucose were markedly reduced after metformin treatment in a dose-dependent manner (P < 0.05). The expression of p-AMPK increased with the rising of metformin concentration, presenting the opposite trend, while the level of total-AMPK protein was unchanged with exposure to HG or metformin. Conlusion Metformin can suppress the expression of NF-κB, MCP-1, ICAM-1 and TGF-β1 of glomerular MCs induced by high glucose via AMPK activation, which may partly contribute to its reno-protection.

AMP-Activated Protein Kinases ; metabolism ; Animals ; Cells, Cultured ; Glomerular Mesangium ; cytology ; Glucose ; pharmacology ; Mesangial Cells ; drug effects ; metabolism ; Metformin ; pharmacology ; NF-kappa B ; metabolism ; Rats

OBJECTIVETo study effects of Chinese Herbal Compounds (CHC) for blood activating stasis removing (BASR), qi benefiting Shen invigorating (QBSI) on high glucose stimulated proliferation of renal mesangial cells (RMCs) and expressions of fibronectin (FN).

METHODSRats' RMCs were dealt with high glucose and different concentrations of Chinese medicine for 24 and 48 h respectively. The proliferation of RMCs was detected with 4-A thiazolyl blue. mRNA expressions of FN was detected by real time quantitative PCR. The protein expression of FN was detected by ELISA.

RESULTSCompared with the control group, the proliferation obviously increased (P < 0.05, P < 0.01) after 24 and 48 h of treatment in the high glucose group, mRNA and protein expressions of FN also increased (P < 0.01). There was no statistical difference in the proliferation of RMCs or expressions of FN at 24 h between each CHC group and the high glucose group (P > 0.05). Compared with the high glucose group, the proliferation of RMCs and expressions of FN at 24 h each obviously decreased in the CHC group (P < 0.05, P < 0.01).

CONCLUSIONSHigh glucose could promote the proliferation of RMCs and induce expressions of FN. No obvious effect could be stimulated by CHC treatment for 24 h. The proliferation of RMCs, protein and mRNA expressions of FN could be reversed by CHC treatment for 48 h.

Animals ; Cells, Cultured ; Drugs, Chinese Herbal ; pharmacology ; Fibronectins ; metabolism ; Glucose ; adverse effects ; Kidney Tubules ; cytology ; Male ; Mesangial Cells ; drug effects ; metabolism ; RNA, Messenger ; genetics ; Rats

OBJECTIVETo investigate the effect of exendin-4 on the expression of monocyte chemoattractant protein-1 (MCP-1) and fibronectin (FN) in rat glomerular mesangial cells in vitro.

METHODSRat glomerular mesangial cells were divided into 5 groups, namely control group, tumor necrosis factor-α (TNF-α) group (10 ng/ml), TNF-α (10 ng/ml)+E1 (1 nmol/L exendin-4) group, TNF-α (10 ng/ml)+E5 (5 nmol/L exendin-4) group, and TNF-α (10 ng/ml)+E10 (10 nmol/L exendin-4) group. After cultured 24 h or 48 h, RNA were extracted to determine the expression of MCP-1 with real-time PCR, the supernatant were collected to determine the expression of MCP-1 and FN with ELISA.

RESULTSCompared with control group, the cells treated with TNF-α for 24 h showed significantly increase the expression of MCP-1 and FN (P<0.01), exendin-4 significantly reduced the expression of MCP-1 and FN in TNF-α+E5 group and TNF-α+E10 group (P<0.05). After 48h incubation, the expression of MCP-1 and FN increased significantly in TNF-α group (P<0.01), which was lowered by exendin-4 in TNF-α+E1,TNF-α+E5 and TNF-α+E10 groups (P<0.05).

CONCLUSIONExendin-4 has an intrinsic capability to concentration- and time-dependently inhibit TNF-α-induced expression of MCP-1 and FN in rat mesangial cells, suggesting the beneficial effect of exendin-4 in preventing and treating diabetic nephropathy.

Animals ; Cells, Cultured ; Chemokine CCL2 ; metabolism ; Diabetic Nephropathies ; metabolism ; Glomerular Mesangium ; cytology ; Mesangial Cells ; drug effects ; metabolism ; Peptides ; pharmacology ; Rats ; Tumor Necrosis Factor-alpha ; pharmacology ; Venoms ; pharmacology

OBJECTIVETo investigate the effects of very low-density lipoprotein (VLDL) on cellular lipid accumulation and the expression of monocyte chemoattractant protein-1 (MCP-1) in human mesangial cells.

METHODSAn established stable human mesangial cell line (HMCL) was used in all experiments. VLDL-induced cellular lipid deposition was visualized by Oil Red O staining and analyzed quantitatively by standard enzymatic procedures. MCP-1 mRNA and protein expression levels in treated HMCLs were determined by real-time quantitative RT-PCR and enzyme-linked immunosorbent assay, respectively. For adhesion study, HMCLs were treated with VLDL for 12 hours, followed by a one-hour incubation with THP-1 cells.

RESULTSVLDL induced cellular lipid accumulation in HMCLs in a time- (0-24 h) and dose- (0-200 microg/ml) dependent manner, and the principal component of accumulated lipid is triglyceride. In HMCLs, MCP-1 mRNA expression was promoted by VLDL in a time- (0-6 h) and dose- (0-100 microg/ml) dependent manner, and VLDL also enhanced MCP-1 secretion in a dose-dependent manner. Such an effect was accompanied by increased adhesion of monocytes to HMCLs.

CONCLUSIONSVLDL can induce cellular triglyceride accumulation and upregulate the expression of MCP-1 in human mesangial cells. Hence, VLDL may be involved in the pathogenesis of lipid-mediated renal injury.

Cell Line ; Chemokine CCL2 ; genetics ; metabolism ; Humans ; Lipoproteins, VLDL ; pharmacology ; toxicity ; Mesangial Cells ; cytology ; metabolism ; RNA, Messenger ; genetics ; metabolism ; Triglycerides ; metabolism

OBJECTIVETo investigate the effects of rapamycin and 3-methyladenine on autophagy impairment, oxidative stress and premature senescence induced by high-glucose in primarily cultured rat mesangial cells.

METHODSRat glomerular mesangial cells (GMCs) were isolated and cultured in normal glucose, high glucose, high glucose with 3-methyladenine (3-MA), or high glucose with rapamycin. At 24 h, 72 h and 10 days of culture, the cells were examined for expression levels of autophagy markers LC3 and p62/SQSTM1, malondialdehyde (MDA) and protein carbonyl, β-galactosidase (SA-β-gal) activity and heterochromatin foci (SAHF).

RESULTSCompared with those of normal cell culture, the cells exposed to high glucose for 72 h and 10 days showed down-regulated LC3 expression, up-regulated p62/SQSTM1 expression, elevated MDA and protein carbonyl levels, and increased SAHF formation and percentage of SA-β-gal-positive cells. These changes were reversed in GMCs exposed to high glucose and rapamycin for 72 h and 10 days, but exacerbated in cells incubated with 3-MA.

CONCLUSIONHigh glucose can suppress autophagic function of rat GMCs to result in oxidative damage and cell senescence. Rapamycin can attenuate autophagy impairment, oxidative damage and senescence induced by high glucose, whereas 3-MA can further aggravate high glucose-induced cell injuries in rat GMCs.

Animals ; Autophagy ; drug effects ; Cells, Cultured ; Cellular Senescence ; drug effects ; Glomerular Mesangium ; cytology ; Glucose ; adverse effects ; Male ; Mesangial Cells ; cytology ; drug effects ; metabolism ; Oxidative Stress ; drug effects ; Rats ; Rats, Sprague-Dawley ; Sirolimus ; pharmacology

The role of serum and glucocorticoid-induced kinase 1 (SGK1) pathway in the connective tissue growth factor (CTGF) expression was investigated in cultured human mesangial cells (HMCs) under high glucose. By using RT-PCR and Western blot, the effect of SGK1 on the CTGF expression in HMCs under high glucose was examined. Overexpression of active SGK1 in HMCs transfected with pIRES2-EGFP-S422D hSGK1 (SD) could increase the expression of phosphorylated SGK1 and CTGF as compared with HMCs groups transfected with pIRES2-EGFP (FP) under high glucose or normal glucose. Overexpression of inactive SGK1 in HMCs transfected with pIRES2-EGFP-K127N hSGK1 (KN) could decrease phosphorylated SGK1 and CTGF expression as compared with HMCs groups transfected with FP under high glucose. In conclusion, these results suggest that high glucose-induced CTGF expression is mediated through the active SGK1 in HMCs.
Cells, Cultured ; Connective Tissue Growth Factor/genetics ; Connective Tissue Growth Factor/*metabolism ; Glucose/*pharmacology ; Immediate-Early Proteins/metabolism ; Immediate-Early Proteins/*physiology ; Mesangial Cells/cytology ; Mesangial Cells/*metabolism ; Protein-Serine-Threonine Kinases/metabolism ; Protein-Serine-Threonine Kinases/*physiology ; Signal Transduction/drug effects

BACKGROUNDThe plasma concentration of very low density lipoprotein (VLDL) is negatively correlated to renal function in glomerular diseases. Effects of VLDL on renal function have been partially attributed to the proliferation of mesangial cells. This study examined the potential role of the p42/44 mitogen activated protein kinase (MAPK) in mesangial cell proliferation induced by VLDL.

METHODSMesangial cells were treated with VLDL at different concentrations or for different time. The cell cycle of the mesangial cells was analyzed by XTT assay and flow-cytometry; MAPK activity was also assayed. In some experiments, cells were treated with VLDL together with or without 0.1 µmol/L PD 98059.

RESULTSTen to 500 µg/ml VLDL stimulated the proliferation of mesangial cells cultured in vitro in a concentration-dependent manner. The effect was associated with an increase in p42/44 MAPK activity. Increased proliferation of mesangial cells by VLDL was significantly attenuated by PD98059, a specific p42/44 MAPK inhibitor.

CONCLUSIONThese results indicate that the p42/44 MAPK pathway is an important regulator of mesangial cell proliferation and of renal functions.

Animals ; Cell Cycle ; drug effects ; Cell Proliferation ; drug effects ; Cells, Cultured ; Lipoproteins, VLDL ; pharmacology ; Male ; Mesangial Cells ; cytology ; drug effects ; Mitogen-Activated Protein Kinase 1 ; metabolism ; Mitogen-Activated Protein Kinase 3 ; metabolism ; Rats ; Rats, Sprague-Dawley

OBJECTIVETo study the role of connective tissue growth factor (CTGF) in the development of glomerulosclerosis by experimental alteration of fibronectin (FN) and Type IV collagen (Col IV) expression in cultured rat mesangial cells (MsC).

METHODSCTGF expression vector was transfected into MsC by Lipofectimine method. Protein and mRNA expression levels of CTGF, FN and Col IV were studied by Western blot and reverse transcription-polymerase chain reaction (RT-PCR) respectively.

RESULTSTwo of MsC clones (MCT-1 and MCT-2) with CTGF overexpression were successfully established and found to have significant increases of FN and Col IV at both protein and mRNA levels. Compared with the controls, the expression of FN protein and mRNA in the two clones were 3.2 times (P < 0.05) and 2.9 times (P < 0.05) higher respectively. The expression of Col IV protein and mRNA was 3.8 times (P < 0.01) and 2.4 times (P < 0.01) higher respectively.

CONCLUSIONCTGF up-regulates FN and Col IV expression in MsC and may play an important role in the development of glomerulosclerosis.

Animals ; Blotting, Western ; Cells, Cultured ; Collagen Type IV ; genetics ; metabolism ; Connective Tissue Growth Factor ; genetics ; metabolism ; Fibronectins ; genetics ; metabolism ; Genetic Vectors ; genetics ; Mesangial Cells ; cytology ; metabolism ; RNA, Messenger ; genetics ; metabolism ; Rats ; Reverse Transcriptase Polymerase Chain Reaction ; Transfection

OBJECTIVETo investigate the role of TRB3 in the inhibitory effect of fenofibrate against the proliferation of glomerular mesangial cell induced by high glucose.

METHODSRat glomerular mesangial cells (MCs) were cultured in the presence of 5.5 mmol/L glucose (normal control), 25 mmol/L glucose (high glucose group), or high glucose along with 10, 50, or 100 µmol/L fenofibrate. Cell counting kit-8 (CCK-8) assay was used to evaluate cell proliferation, and Hoechst 33258 staining was employed to determine chromatin distribution in the MCs. Flow cytometry was performed to analyze the cell cycle changes in different groups. The expressions of TRB3 and P-AKT in different groups were detected using immunocytochemistry and Western blotting.

RESULTSHigh glucose induced obvious proliferation of the MCs (P<0.001), which was significantly inhibited by fenofibrate in a concentration-dependent manner (P<0.001). The MCs exposed to fenofibrate presented with typical apoptotic morphologies and cell cycle arrest at G1/S phase. Low levels of TRB3 expression was detected in the normal control and high glucose groups, whereas in the 3 fenofibrate groups, TRB3 expression increased and P-AKT expression decreased as fenofibrate concentration increased.

CONCLUSIONFenofibrate can promote TRB3 expression in rat MCs. TRB3 causes cell cycle arrest at G1/S phase by inhibiting AKT phosphorylation to result in suppressed proliferation of the MCs.

Animals ; Cell Cycle Checkpoints ; Cell Proliferation ; drug effects ; Cells, Cultured ; Fenofibrate ; pharmacology ; Glucose ; adverse effects ; metabolism ; Mesangial Cells ; cytology ; drug effects ; Phosphorylation ; Protein-Serine-Threonine Kinases ; antagonists & inhibitors ; metabolism ; Proto-Oncogene Proteins c-akt ; metabolism ; Rats ; Signal Transduction

OBJECTIVETo explore effects of beraprost sodium (BPS) on the metabolism of extracellular matrix (ECM) in rat mesangial cells cultured in the presence of high glucose and the possible mechanism.

METHODSRat mesangial cells were cultured in the presence of high glucose with or without BPS for 24 or 48 h. The levels of transforming growth factor β1 (TGFβ1), fibronectin (FN) and matrix metalloproteinase-2 (MMP-2) protein in the culture supernatants were measured by enzyme-linked immunosorbent assay, and photoshop-Smad3 was detected by Western blotting.

RESULTSCompared with the cells in normal glucose, the cells cultured in the presence of high glucose for 24 and 48 h showed significantly increased TGFβ 1 and FN protein expression and lowered MMP-2 protein expression (P<0.01). Compared with the cells cultured in high glucose, BPS exposure at the concentration of 1, 2, and 5 µmol/L for 24 and 48 h significantly lowered TGFβ 1 protein expression (P<0.01), and at 2 and 5 µmol/L, BPS significantly decreased FN protein expression and increased MMP-2 protein expression in high glucose-induced cells (P<0.05). High glucose exposure also significantly increased the expression phosphorylated Smad3 (P<0.01), which was lowered by BPS treatment at 2 and 5 µmol/L (P<0.01).

CONCLUSIONBPS can regulate ECM metabolism in rat mesangial cells cultured in high glucose by inhibiting TGFβ 1/Smad3 pathway, suggesting the beneficial effects of BPS in preventing and treating diabetic nephropathy.

Animals ; Cell Line ; Cells, Cultured ; Diabetic Nephropathies ; Enzyme-Linked Immunosorbent Assay ; Epoprostenol ; analogs & derivatives ; pharmacology ; Extracellular Matrix ; metabolism ; Fibronectins ; metabolism ; Glomerular Mesangium ; cytology ; Glucose ; Matrix Metalloproteinase 2 ; metabolism ; Mesangial Cells ; drug effects ; Rats ; Transforming Growth Factor beta1 ; metabolism