The angiotensin-converting enzyme (ACE) gene DD homozygote has been suggested to be a significant risk factor for the progression of diabetic nephropathy. We analyzed clinical parameters and ACE genotype distribution between type 2 diabetic patients at the extremes of renal risk, i.e. an end-stage renal failure (ESRF) group (n = 103, group 1) who were on dialysis therapy due to progression of diabetic nephropathy, and a no progression group (n = 88, group 2) who had maintained normal renal function and normoalbuminuria for more than 15 years. There were no significant differences in age, sex, body mass index, HbA1c level, or lipid profiles between the two groups (p > 0.05). Group 1 had a significantly higher prevalence of hypertension [group 1: 82.5% (85/103) vs. group 2: 50.0% (44/88), p < 0.05] and diabetic retinopathy [group 1: 103/103 (100%) vs. group 2: 28/88 (31.8%), p < 0.05] than group 2. Daily urinary albumin excretion was also higher in group 1 than in group 2 [group 1: 2873 +/- 2176 mg/day vs. 12 +/- 7 g/day, p < 0.05]. The frequencies of the DD, ID, and II genotypes of the ACE gene in group 1 and group 2 were 26.2%, 47.6%, and 26.2%, and 7.9%, 57.9%, and 34.2%, respectively. The ACE genotype frequencies between the two groups were significantly different according to a chi-square test with Bonferroni's correction (p = 0.004). The presence of the DD genotype increased the risk of ESRF 4.286-fold compared to the II genotype [odds ratio 4.286, 95% CI 1.60- 11.42, p = 0.005]. The frequency of the D-allele was higher in both male and female patients in group 1 compared to group 2, but reached statistical significance only in males [male, group 1: 50.8% vs. group 2: 35.0%, p = 0.018, female, group 1: 48.8% vs. group 2: 39.5%, p = 0.231]. This study, although limited by sample size, showed that type 2 diabetic ESRF patients more frequently expressed the DD genotype. These findings may substantiate the previously noted relationship between the ACE DD genotype and the progression of diabetic nephropathy in Korean type 2 diabetic patients.
Renal Dialysis ; *Polymorphism, Genetic ; Peptidyl-Dipeptidase A/*genetics/metabolism ; Middle Aged ; Male ; Kidney Failure, Chronic/diagnosis/*genetics ; Humans ; Homozygote ; Gene Frequency ; Female ; Diabetic Nephropathies/diagnosis/*genetics ; Diabetes Mellitus, Type 2/diagnosis/*genetics ; Aged

BACKGROUND/AIMS: Renal hypoxia is involved in the pathogenesis of diabetic nephropathy. Pentoxifyllin (PTX), a nonselective phosphodiesterase inhibitor, is used to attenuate peripheral vascular diseases. To determine whether PTX can improve renal hypoxia, we investigated its effect in the streptozocin (STZ)-induced diabetic kidney. METHODS: PTX (40 mg/kg, PO) was administered to STZ-induced diabetic rats for 8 weeks. To determine tissue hypoxia, we examined hypoxic inducible factor-1alpha (HIF-1alpha), heme oxygenase-1 (HO-1), vascular endothelial growth factor (VEGF), and glucose transporter-1 (GLUT-1) levels. We also tested the effect of PTX on HIF-1alpha in renal tubule cells. RESULTS: PTX reduced the increased protein creatinine ratio in diabetic rats at 8 weeks. HIF-1alpha, VEGF, and GLUT-1 mRNA expression increased significantly, and the expression of HO-1 also tended to increase in diabetic rats. PTX significantly decreased mRNA expression of HIF-1alpha and VEGF at 4 and 8 weeks, and decreased HO-1 and GLUT-1 at 4 weeks. The expression of HIF-1alpha protein was significantly increased at 4 and 8 weeks in tubules in the diabetic rat kidney. PTX tended to decrease HIF-1alpha protein expression at 8 weeks. To examine whether PTX had a direct effect on renal tubules, normal rat kidney cells were stimulated with CoCl2 (100 microM), which enhanced HIF-1alpha mRNA and protein levels under low glucose conditions (5.5 mM). Their expressions were similar even after high glucose (30 mM) treatment. PTX had no effect on HIF-1alpha expression. CONCLUSIONS: PTX attenuates tubular hypoxia in the diabetic kidney.
Animals ; Anoxia/*drug therapy/enzymology/etiology/genetics ; Cell Line ; Cobalt/pharmacology ; Diabetes Mellitus, Experimental/*complications ; Diabetic Nephropathies/*drug therapy/enzymology/etiology/genetics ; Disease Models, Animal ; Gene Expression Regulation/drug effects ; Glucose/metabolism ; Glucose Transporter Type 1/genetics ; Heme Oxygenase (Decyclizing)/genetics/metabolism ; Hypoxia-Inducible Factor 1, alpha Subunit/genetics/metabolism ; Kidney Tubules/*drug effects/enzymology ; Male ; Pentoxifylline/*pharmacology ; Phosphodiesterase Inhibitors/*pharmacology ; RNA, Messenger/metabolism ; Rats ; Rats, Sprague-Dawley ; Streptozocin ; Time Factors ; Vascular Endothelial Growth Factor A/genetics

The presence of heparan sulfate proteoglycan (HSPG) in anionic sites in the lamina rara interna of glomerular basement membrane suggests that the proteoglycan may be deposited by the glomerular endothelial cells (GEndo). We have previously demonstrated that bovine GEndo in vitro synthesize perlecan, a species of glomerular basement membrane HSPG. In this study we examined whether high glucose medium regulates the GEndo metabolism of glycopeptides including perlecan. Metabolic labeling of glycoconjugates with 35S-SO4, sequential ion exchange and Sepharose CL-4B chromatography of labeled glycoconjugates, and northern analysis were performed. Incubation of GEndo for 8 to 14 weeks (but not for 1-2 weeks) in medium containing 30 mM glucose resulted in nearly 50% reduction in the synthesis of cell layer and medium 35SO4-labeled low anionic glycoproteins and proteoglycans, including that of basement membrane HSPG (Kav 0.42) compared to GEndo grown in 5 mM glucose medium; no changes in anionic charge density or hydrodynamic size of proteoglycans were noted. Northern analysis demonstrated that the mRNA abundance of perlecan was reduced by 47% in cells incubated with 30 mM glucose. Our data suggest that high glucose medium reduces the GEndo synthesis of perlecan by regulating its gene expression. Reduced synthesis of perlecan by GEndo may contribute to proteinuria seen in diabetic nephropathy.
Animals ; Basement Membrane/drug effects/metabolism ; Cattle ; Cells, Cultured ; Diabetic Nephropathies/metabolism ; Endothelial Cells/cytology/*drug effects/*metabolism ; Gene Expression/drug effects ; Glucose/*pharmacology ; Heparan Sulfate Proteoglycan/genetics/*metabolism ; Kidney Glomerulus/*cytology ; Sulfur Radioisotopes/diagnostic use ; Support, Non-U.S. Gov't ; Support, U.S. Gov't, Non-P.H.S. ; Support, U.S. Gov't, P.H.S.

Diabetic nephropathy is the most serious complication in diabetes mellitus. It is known that oxidative stress and inflammation play a central role in the development of diabetic nephropathy. In this study, we investigated that ferulic acid (FA) known as anti-oxidative agent could effect on diabetic nephropathy by anti-oxidative and anti-inflammatory mechanism. We examined the effects of FA in obese diabetic Otsuka Long-Evans Tokushima Fatty (OLETF) rats and non-diabetic control Long-Evans Tokushima Otsuka (LETO) rats. We treated FA to experimental rats from 26 to 45 weeks of age. We evaluated ACR, MDA and MCP-1 in 24 h urine and examined renal histopathology and morphologic change in extracted kidneys from rats. Also, we evaluated the ROS production and MCP-1 levels in cultured podocyte after FA treatment. In the FA-treated OLETF rats, blood glucose was significantly decreased and serum adiponectin levels were increased. Urinary ACR was significantly reduced in FA-treated OLETF rats compared with diabetic OLETF rats. In renal histopathology, FA-treated OLETF rats showed decreased glomerular basement membrane thickness, glomerular volume, and mesangial matrix expansion. FA treatment decreased oxidative stress markers and MCP-1 levels in 24 h urine of rats and supernatants of cultured podocyte. In conclusion, it was suggested that FA have protective and therapeutic effects on diabetic nephropathy by reducing oxidative stress and inflammation.
Animals ; Anti-Inflammatory Agents, Non-Steroidal/*therapeutic use ; Antioxidants/*therapeutic use ; Cells, Cultured ; Chemokine CCL2/genetics/urine ; Collagen/analysis ; Coumaric Acids/*therapeutic use ; Diabetes Mellitus, Type 2/*complications ; Diabetic Nephropathies/*complications/*drug therapy/pathology ; Gene Expression/drug effects ; Kidney/drug effects/pathology ; Malondialdehyde/urine ; Podocytes/drug effects/metabolism ; Rats ; Rats, Inbred OLETF ; Reactive Oxygen Species/metabolism ; Transforming Growth Factor beta1/analysis

We aimed to elucidate the effect of bilirubin on dyslipidemia and nephropathy in a diabetes mellitus (DM) type I animal model. Sprague-Dawley rats were separated into control, DM, and bilirubin-treated DM (Bil) groups. The Bil group was injected intraperitoneally with 60 mg/kg bilirubin 3 times per week and hepatoma cells were cultured with bilirubin at a concentration of 0.3 mg/dL. The Bil group showed lower serum creatinine levels 5 weeks after diabetes onset. Bilirubin treatment also decreased the amount of mesangial matrix, lowered the expression of renal collagen IV and transforming growth factor (TGF)-beta1, and reduced the level of apoptosis in the kidney, compared to the DM group. These changes were accompanied by decreased tissue levels of hydrogen superoxide and NADPH oxidase subunit proteins. Bilirubin decreased serum total cholesterol, high-density lipoprotein cholesterol (HDL-C), free fatty acids, and triglycerides (TGs), as well as the TG content in the liver tissues. Bilirubin suppressed protein expression of LXRalpha, SREBP-1, SCD-1, and FAS, factors involved in TG synthesis that were elevated in the livers of DM rats and hepatoma cells under high-glucose conditions. In conclusion, bilirubin attenuates renal dysfunction and dyslipidemia in diabetes by suppressing LXRalpha and SREBP-1 expression and oxidative stress.
Animals ; Bilirubin/pharmacology/*therapeutic use ; Cell Line, Tumor ; Creatine/blood ; Diabetes Mellitus, Experimental/chemically induced/complications/*pathology ; Diabetic Nephropathies/*drug therapy/etiology ; Disease Models, Animal ; Kidney/pathology ; Lipoproteins, HDL/blood ; Liver/metabolism ; Male ; Mice ; Mice, Inbred C57BL ; NADPH Oxidase/metabolism ; Orphan Nuclear Receptors/antagonists & inhibitors/genetics/metabolism ; Oxidative Stress/drug effects ; Rats ; Rats, Sprague-Dawley ; Reactive Oxygen Species/metabolism ; Streptozocin/toxicity ; Triglycerides/analysis/*biosynthesis/blood