Effect of the Direct Renin Inhibitor Aliskiren on Urinary Albumin Excretion in Spontaneous Type 2 Diabetic KK-A (y) Mouse.

Objective. Although angiotensin II-mediated inflammation and extracellular matrix accumulation are considered to be associated with the progression of diabetic nephropathy, these processes have not yet been sufficiently clarified. The objective of this study was to determine whether the correction of the abnormal renal expression of MMPs and its inhibitors (MMPs/TIMPs) and cytokines following the administration of aliskiren to KK-A (y) mice results in a renoprotective effect. Methods. KK-A (y) mice were divided into two groups, that is, untreated (saline) and treated (aliskiren) groups. Systolic BP, HbA1c levels, and the albumin-creatinine ratio (ACR) were measured. The renal expression of MMPs/TIMPs, fibronectin, type IV collagen, MCP-1, and (pro)renin receptor ((P)RR) was examined using real-time PCR and/or immunohistochemical staining. Renal MAPK and NF- κ B activity were also examined by Western blot analyses and ELISA, respectively. Results. Significant decreases in systolic BP and ACR levels were observed in treated KK-A (y) mice compared with the findings in untreated KK-A (y) mice. Furthermore, increases in MMPs/TIMPs, fibronectin, type IV collagen, MCP-1, and (P)RR expression, in addition to MAPK and NF- κ B activity, were significantly attenuated by aliskiren administration. Conclusions. It appears that aliskiren improves albuminuria and renal fibrosis by regulating inflammation and the alteration of collagen synthesis and degradation.

Pathogenesis and novel treatment from the mouse model of type 2 diabetic nephropathy.

Diabetic nephropathy (DN) is the leading cause of end-stage kidney disease worldwide. However, current treatments remain suboptimal. Many factors, such as genetic and nongenetic promoters, hypertension, hyperglycemia, the accumulation of advanced glycation end products (AGEs), dyslipidemia, and albuminuria/proteinuria itself, influence the progression of this disease. It is important to determine the molecular mechanisms and treatment of this disease. The development of diabetes results in the formation of AGEs, oxidative stress, and the activation of the renin-angiotensin-aldosterone system (RAAS) within the kidney, which promotes progressive inflammation and fibrosis, leading to DN and declining renal function. A number of novel therapies have also been tested in the experimental diabetic model, including exercise, inhibitors of the RAAS (angiotensin type 1 receptor blockers (ARB), angiotensin-converting enzyme (ACE) inhibitors), inhibitors of AGE (pyridoxamine), peroxisome proliferator-activated receptor (PPAR) γ agonists (pioglitazone), inhibitors of lipid accumulation (statins and eicosapentaenoic acid (EPA)), and the vitamin D analogues. This review summarizes the advances in knowledge gained from our studies and therapeutic interventions that may prevent this disease.

Effect of exercise on kidney function, oxidative stress, and inflammation in type 2 diabetic KK-A(y) mice.

Exercise is recommended for the management of type 2 diabetes, but its effects on diabetic nephropathy (DN) are still unknown. We hypothesized that appropriate exercise improves early DN via attenuation of inflammation and oxidative damage. Type 2 diabetic KK-A(y) mice, a spontaneous DN model, underwent two different kinds of exercise (i.e., moderate and low intensity). Sedentary mice or those undergoing an exercise regimen causing no significant body weight loss were used. We examined the urinary excretion of albumin, number of podocytes and macrophages, renal expressions of HIF-1α and MCP-1, and biomarkers of oxidative stress such as urinary 8-OHdG and serum SOD. Exercise reduced urinary levels of albumin and also maintained the number of podocytes in the exercised KK-A(y) mice independently of improvements of overweight and hyperglycemia, although moderate-intensity exercise increased expression of HIF-1α. Sedentary KK-A(y) mice showed increased expression of MCP-1 and infiltration of macrophage, increased urinary 8-OhdG, and decreased serum SOD levels compared with exercised KK-A(y) mice. On the whole, low-intensity exercise attenuates progression of early DN without affecting marked renal ischemia. Reduction rates of urinary albumin and maintained podocyte numbers, with parallel improvements in oxidative damage and inflammation, are related to beneficial effects of exercise in diabetic kidney disease.

Risk of overestimation of kidney function using GFR-estimating equations in patients with low inulin clearance.

BACKGROUND: Accurate estimation of the glomerular filtration rate (GFR) is very important in clinical practice. Although renal inulin clearance (Cin) is the gold standard for measuring GFR, the procedure for Cin measurement is complicated. Use of GFR-estimating equations has been increasing recently due to their simplicity. The objectives of the present study are to analyze the correlation between Cin and other GFR-estimating parameters and to investigate their clinical usefulness and limitation. METHODS: Seventy-two Japanese patients were enrolled in this study. Cin was measured by the continuous infusion method. Serum creatinine (s-Cr), cystatin C, uric acid (UA), and hemoglobin (Hb) were measured. The Japanese formula of estimated GFR (eGFR) was as follows: eGFR (ml/min/1.73m(2) ) = 194 × s-Cr(-1.094) × Age(-0.287) × 0.739 (if female). The endogenous creatinine clearance test was also performed. RESULTS: Levels of Cin were highly correlated with those of endogenous creatinine clearance (Ccr) (R(2) = 0.7585) and eGFR (R(2) = 0.5659). However, patients with lower Cin showed unexpectedly elevated levels of endogenous Ccr and eGFR. Moreover, the levels of eGFR tended to be unexpectedly increased in patients with low body surface area. CONCLUSION: Although GFR-estimating equations are useful for estimating GFR accurately, they pose a risk of overestimation of kidney function in patients with decreased GFRor a poor physique.

Identification of quantitative trait loci for diabetic nephropathy in KK-Ay/Ta mice.

BACKGROUND: The pathogenesis and development of human diabetic nephropathy involves genetic factors. Since human diabetic nephropathy is a heterogeneous disorder, identification of responsible gene loci is difficult. We studied candidate gene loci for diabetic nephropathy, using quantitative trait locus (QTL) analysis of a spontaneous animal model for diabetic nephropathy: KK-Ay/Ta × normal BALB/cA F2 intercross mice. METHODS: We examined 270 (KK-Ay/Ta × BALB/cA) F2 intercross mice for their urinary albumin to creatinine ratios (ACRs), HbA1c and fasting body weights (FBW) at 8, 12, 16 and 20 weeks. Genotypes were investigated using 86 microsatellite markers with QTL analysis. RESULTS: ACR in mice at 20 weeks and ACR gain showed a suggestive linkage to chromosome 9 (log of the odds [LOD] scores: 3.8 and 3.4, respectively; designated ACR-1). Gene loci contributing to HbA1c indicated a significant linkage to chromosome 7 (LOD: 5.8 and 8.9) in mice at 8 and 20 weeks (designated HbA1c-1), and FBW indicated a significant linkage to chromosome 1 (LOD: 5.5 and 5.2) in mice at 8 and 12 weeks (designated Fbw-1). At 20 weeks, glomerular to Bowman's capsule volume (G/B) ratio of F2 mice homozygous BB for D9Mit66 was significantly higher than that in homozygous KK and heterozygous KB F2 progeny. The sizes of pancreatic islets in F2 progeny homozygous KK and heterozygous KB for D7Mit100 were larger than those in homozygous BB F2 progeny. CONCLUSION: QTL analysis of KK-Ay/Ta mice revealed several new loci contributing to diabetic nephropathy and related phenotypes. Thus, it appears that type 2 diabetes and nephropathy of KK-Ay/Ta mice have different genetic factors.

Effects of acetate-free citrate dialysate on glycoxidation and lipid peroxidation products in hemodialysis patients.

BACKGROUND/AIMS: Previous studies have shown the presence of high levels of glycoxidation and lipid peroxidation products in association with atherosclerosis in patients with end-stage kidney disease. Acetates are commonly used buffer for correcting metabolic acidosis in hemodialysis (HD) patients. Since the toxic effects of acetates are well established, acetate-free citrate dialysate (AFD) has become available in Japan. The objective of the present study was to evaluate the suppressive effects of AFD on oxidative stress in maintenance HD patients by measuring plasma pentosidine and malondialdehyde-modified low-density lipoprotein (MDA-LDL) levels as markers for glycoxidation and lipid peroxidation products. METHODS: Plasma pentosidine, MDA-LDL and other laboratory parameters were examined on maintenance HD at the Juntendo University Hospital before and after switching to AFD. RESULTS: MDA-LDL levels divided by LDL cholesterol were significantly lower than those before switching to AFD. Furthermore, levels of plasma pentosidine were lower than those before switching to AFD. Stepwise multiple regression analysis revealed that the percent change of the calcium-phosphorus product in the nondiabetic group and that of phosphorus in the diabetic group were predictive variables for the percent change of MDA-LDL/LDL, whereas the percent change of log high-sensitive C-reactive protein and that of systolic blood pressure in the nondiabetic group and that of diastolic blood pressure in the diabetic group were predictive variables for the percent change of plasma pentosidine. CONCLUSIONS: It appears that AFD decreases glycoxidation and lipid peroxidation products when compared with acid citrate dextrose in HD patients. The reduction of oxidative stress by AFD during HD may have possible beneficial effects on atherosclerosis through calcium-phosphorus metabolism and blood pressure.

Relationship between preoperative radial artery and postoperative arteriovenous fistula blood flow in hemodialysis patients.

BACKGROUND: It is recommended that arteriovenous fistula (AVF) blood flow should be more than 425 ml/min before cannulation. However, the relationship between preoperative radial artery flow (RAF) and postoperative AVF blood flow has still not been examined. METHODS: Sixty-one patients with end-stage kidney disease (ESKD) were examined. They had an AVF prepared at Juntendo University Hospital from July 2006 through August 2007. Preoperative RAF and postoperative AVF blood flows were measured by ultrasonography. RESULTS: AVF blood flow gradually increased after the operation. AVF blood flow was significantly correlated with preoperative RAF. When preoperative RAF exceeded 21.4 ml/min, AVF blood flow rose to more than 425 ml/min. The postoperative AVF blood flow in the group with RAF of more than 20 ml/min was significantly higher than that in those with less than 20 ml/min. Preoperative RAF of less than 20 ml/min had a significantly high risk of primary AVF failure within 8 months compared with that of more than 20 ml/min. CONCLUSIONS: It appears that measurement of RAF by ultrasonography is useful for estimating AVF blood flow postoperatively and can predict the risk of complications in ESKD patients.

Attenuating effect of angiotensin-(1-7) on angiotensin II-mediated NAD(P)H oxidase activation in type 2 diabetic nephropathy of KK-A(y)/Ta mice.

ANG-(1-7) is associated with vasodilation and nitric oxide synthase stimulation. However, the role of ANG-(1-7) in type 2 diabetes mellitus is unknown. In this study, we examined the hypothesis that ANG-(1-7) attenuates ANG II-induced reactive oxygen species stress (ROS)-mediated injury in type 2 diabetic nephropathy of KK-A(y)/Ta mice. KK-A(y)/Ta mice were divided into four groups: 1) a control group; 2) ANG II infusion group; 3) ANG II+ANG-(1-7) coinfusion group; and 4) ANG II+ANG-(1-7)+d-Ala(7)-ANG-(1-7) (A779) coinfusion group. In addition, primary mesangial cells were cultured and then stimulated with 25 mM glucose with or without ANG II, ANG-(1-7), and A779. The ANG II+ANG-(1-7) coinfusion group showed a lower urinary albumin/creatinine ratio increase than the ANG II group. ANG-(1-7) attenuated ANG II-mediated NAD(P)H oxidase activation and ROS production in diabetic glomeruli and mesangial cells. ANG II-induced NF-κB and MAPK signaling activation was also attenuated by ANG-(1-7) in the mesangial cells. These findings were related to improved mesangial expansion and to fibronectin and transforming growth factor-ß1 production in response to ANG II and suggest that ANG-(1-7) may attenuate ANG II-stimulated ROS-mediated injury in type 2 diabetic nephropathy. The ACE2-ANG-(1-7)-Mas receptor axis should be investigated as a novel target for treatment of type 2 diabetic nephropathy.

Predictive factors associated with the period of time before initiation of hemodialysis in CKD stages 4 and 5.

BACKGROUND: A majority of patients with chronic kidney disease (CKD) have cardiovascular disease at the initiation of dialysis therapy, suggesting that periodic echocardiographic examinations are important in such patients. The purpose of the present study was to evaluate the correlation between echocardiographic parameters and period of time before initiation of hemodialysis (iHD) in patients with CKD. METHODS: 140 patients with CKD stages 4 and 5 were enrolled. They were divided into diabetes and nondiabetes groups. Cardiac predictive parameters for the period of time before iHD were investigated in the patients using univariate and multivariate regression analyses. RESULTS: In the nondiabetes group, systolic blood pressure (SBP) and left atrial volume index (LAVi) were identified as independent risk factors for the period of time before iHD by multivariate regression analysis. Serum albumin level was identified as an independent risk factor in the diabetes group. SBP, LAVi and serum albumin level were identified as independent risk factors in the combined diabetes and nondiabetes groups. CONCLUSION: LAVi measurements during echocardiography, together with SBP and serum albumin levels, may be useful predictive factors for the period of time before iHD in patients with CKD stages 4 and 5.

Effect of combination therapy with angiotensin receptor blocker and 1,25-dihydroxyvitamin D(3) in type 2 diabetic nephropathy in KK-A(y)/Ta mice.

BACKGROUND: Although angiotensin II type 1 receptor blockers (ARB) have beneficial effects in patients with diabetic nephropathy, they may induce a compensatory increase in renin. Renin exhibits profibrotic actions independent of angiotensin II, which is regulated by extracellular signal-regulated kinase 1 and 2 (ERK1/2). Calcitriol (1,25(OH)(2)D(3)) is a negative inhibitor of the renin-angiotensin system and the present study examined the effects of combination therapy with an ARB and 1,25(OH)(2)D(3) on diabetic nephropathy in KK-A(y)/Ta mice. METHODS: KK-A(y)/Ta mice were divided into four groups: ARB group, 1,25(OH)(2)D(3) group, combination group, and control group. The urinary albumin/creatinine ratio (ACR) was measured and the renal expression of renin, p-ERK1/2 and TGF-ß1 protein determined. RESULTS: The levels of urinary ACR in the combination group were significantly lower than those in the ARB or control group. Renal expression of renin in the ARB group was significantly increased compared with the control group but was significantly decreased in both the 1,25(OH)(2)D(3) and combination group. Renal expression of p-ERK1/2 in the combination group was significantly decreased compared with the control or ARB group. Expression of TGF-ß1 protein in the ARB and combination groups, especially the combination group, was significantly decreased compared with those in the control group. CONCLUSIONS: These data suggest that the addition of 1,25(OH)(2)D(3) to therapy with ARB further reduced proteinuria by suppressing the compensatory increase in renin expression in type 2 diabetic nephropathy. These effects might relate to suppression of renin, ERK1/2 and TGF-ß1 expression which may or may not depend on angiotensin II.

Mindin: a novel marker for podocyte injury in diabetic nephropathy.

BACKGROUND: GeneChip Expression Analysis was employed to survey the glomerular gene expression profile in a type 2 diabetes (T2D) model of KK/Ta mice fed with a high-calorie diet (HC), and we focused on the role of mindin (also called spondin 2), whose expression is upregulated by HC. METHODS: Isolated glomeruli from three 20-week-old KK/Ta mice fed with HC or a standard diet (SD) were dissected. Total RNA was extracted and labelled for hybridization using the Affymetrix GeneChip Mouse Genome 430 2.0 Array. The gene expression profile was compared between the HC and SD groups using GeneSpring 7.3.1 software. Mindin expression was examined using real-time PCR, western blot analysis and immunohistochemical staining in the glomeruli, cultured podocytes and urine samples of both mice and humans. RESULTS: Podocyte foot process effacement was observed in mice fed with HC. The mindin protein expression levels in mice were localized in the podocytes, and their levels in the glomeruli were increased in the HC group compared with the SD group. The levels of urinary mindin in the HC group at 16 weeks of age were also significantly higher than those in the SD group although albumin/creatinine ratio (ACR) did not differ between the groups. Furthermore, the levels in patients with T2D were higher than those in healthy individuals and increased gradually with increases in ACR. CONCLUSIONS: Mindin could be related to podocyte injury and appears to be an early biomarker of the progression of diabetic nephropathy.

Predictive factors associated with left ventricular hypertrophy at baseline and in the follow-up period in non-diabetic hemodialysis patients.

Hemodialysis (HD) patients frequently have an elevated left ventricular mass index (LVMI). Currently, left ventricular (LV) hypertrophy and dysfunction are considered to be the strongest predictors of cardiovascular mortality in dialysis patients. The objectives of the present study are to investigate the factors associated with elevated LVMI and to discuss therapeutic implications for the treatment strategy for pre-dialysis and HD patients. The correlation among biochemical values, physical specimens, and LVMI using echocardiography was prospectively analyzed in 30 non-diabetic HD patients in the Juntendo University Hospital. Measurement of these parameters was performed at 0, 12, and 24 months after initiation of HD. Systolic blood pressure (SP), human atrial natriuretic peptide (hANP), and hemoglobin (Hb) levels were significantly correlated with LVMI. SBP, residual glomerular filtration rate (rGFR), and serum albumin levels were identified as independent risk factors for LVMI in multivariate regression analysis at initiation of HD. SBP, hANP, and Hb levels were identified as independent risk factors for LVMI in multivariate regression analysis after 24 months. SBP, rGFR, and serum albumin levels were predictive factors for LVMI at initiation of HD. SBP, hANP, and Hb levels were also predictive factors for LVMI after initiation of HD.

Role of mindin in diabetic nephropathy.

A number of studies have shown that proinflammatory cytokines have important roles in determining the development of microvascular diabetic complications, including nephropathy. Inflammatory biomarkers should be useful for diagnosis or monitoring of diabetic nephropathy. Mindin (spondin 2) is a member of the mindin-/F-spondin family of secreted extracellular matrix (ECM) proteins. Recent studies showed that mindin is essential for initiation of innate immune response and represents a unique pattern-recognition molecule in the ECM. Previously, we demonstrated that the levels of urinary mindin in patients with type 2 diabetes were higher than those in healthy individuals. We propose that urinary mindin is a potent biomarker for the development of diabetic nephropathy.

Combination effects of enalapril and losartan on lipid peroxidation in the kidneys of KK-Ay/Ta mice.

BACKGROUND: Adenosine monophosphate activated protein kinase (AMPK) has a protective effect on lipid peroxidation. Adiponectin and AMPK might have a role in the pathogenesis of diabetic nephropathy. Blockade of the renin-angiotensin system (RAS) increases adiponectin levels and reduces oxidative stress. The objective of the present study was to examine lipid peroxidation via adiponectin and AMPK activation in the kidneys of KK-A(y)/Ta mice by RAS inhibitors, such as enalapril and/or losartan. METHODS: KK-A(y)/Ta mice were given enalapril (2.5 mg/kg/day) and/or losartan (25 mg/kg/day), or hydralazine (25 mg/kg/day) in the drinking water for 8 weeks starting at 8 weeks of age. They were divided into 5 groups as follows: enalapril 2.5 mg/kg/day treatment group (n = 5), losartan 25 mg/kg/day treatment group (n = 5), enalapril 2.5 mg/kg/day + losartan 25 mg/kg/day combination treatment group (n = 5), hydralazine 25 mg/kg/day treatment group (n = 5) and tap water group as the untreated group (n = 5). The urinary albumin/creatinine ratio (ACR), serum adiponectin and systemic blood pressure were measured as test parameters. Expressions of adiponectin, phospho-AMPKalpha (p-AMPKalpha) and phospho-acetyl CoA carboxylase(beta) (p-ACC(beta)) in the kidneys were evaluated by Western blot analyses. Pathological changes of glomeruli were evaluated by light microscopy. Accumulations of N(epsilon)-(carboxymethyl) lysine (CML), malondialdehyde (MDA) and 4-hydroxy-2-nonenal (4-HNE) in glomeruli were evaluated by immunohistochemical analyses. RESULTS: Enalapril and/or losartan improved levels of urinary ACR with activation of adiponectin, p-AMPKalpha and p-ACC(beta) in the kidneys. CML, MDA and 4-HNE expressions in glomeruli were significantly suppressed by enalapril and/or losartan, especially in the combination treatment group. CONCLUSIONS: It appears that enalapril and/or losartan, especially in combination, inhibited accumulation of CML/MDA/4-HNE in diabetic renal tissues. These effects might be related to lipid peroxidation via tissue-specific activation of adiponectin and AMPK.

Contribution of subcutaneous fat accumulation to insulin resistance and atherosclerosis in haemodialysis patients.

BACKGROUND: Whereas visceral fat accumulation (VFA) is related to insulin resistance and atherosclerosis in both haemodialysis (HD) patients and the general population, little is known about the role of subcutaneous fat accumulation (SFA). The purpose of the present study was to examine and confirm the relationship between abdominal fat accumulation (AFA) and various clinical parameters in HD patients. METHODS: Two hundred and thirty-three HD patients were recruited, including 120 with type 2 diabetes. Abdominal fat distribution was evaluated by computed tomography (CT) scans. Systemic atherosclerosis was assessed by intima-media thickness (IMT) using high-resolution B-mode ultrasonography. The insulin resistance was estimated by the homeostasis model assessment-insulin resistance (HOMA-IR). RESULTS: Spearman's analysis revealed that both VFA and SFA showed a significant relationship with HOMA-IR and also that SFA was correlated significantly with IMT in all HD patients. SFA was an independent risk factor associated with HOMA-IR and IMT in multiple regression analysis. Neither body mass index (BMI) nor VFA was a predominant determinant of HOMA-IR and IMT. IMT in HD patients with high SFA/low BMI groups was significantly higher than in the low SFA/high BMI groups. CONCLUSION: It appears that there is a close relationship between SFA and insulin resistance or atherosclerosis in HD patients. It was suggested that SFA plays important roles related to carbohydrate or lipid metabolism in HD patients.

Effects of pyridoxamine (K-163) on glucose intolerance and obesity in high-fat diet C57BL/6J mice.

Advanced glycation end products (AGEs) contribute to the pathogenesis of diabetes-associated complications. Previously, we reported the possible effect of pyridoxamine (K-163), an AGE inhibitor, on improvement of glucose intolerance in type 2 diabetes mellitus KK-A(y)/Ta mice. Recently, AGEs and oxidative stress have been shown to induce insulin resistance. The objective of the present study is to examine the effect of pyridoxamine on glucose intolerance and oxidative stress. C57BL/6J mice were divided into 3 groups as follows: low-fat diet, high-fat diet, and high-fat diet with pyridoxamine treatment. Body and adipose tissue weight, serum insulin, hydrogen peroxide, malondialdehyde and AGE, and urinary 8-hydroxy-2'-deoxyguanosine levels were measured. Nicotinamide adenine dinucleotide phosphate subunits, antioxidant enzymes, and adipocytokine messenger RNA expressions in the adipose tissues were evaluated. Akt/protein kinase B activity and glucose transporter 4 translocation in skeletal muscle were also evaluated. Body and adipose tissue weights of the pyridoxamine treatment group were significantly decreased compared with those of the high-fat diet group. Pyridoxamine attenuated serum hydrogen peroxide, malondialdehyde and AGE, and urinary 8-hydroxy-2'-deoxyguanosine and nicotinamide adenine dinucleotide phosphate oxidase expression; increased antioxidant enzyme expression; and improved dysregulation of adipocytokines in adipose tissues. Pyridoxamine improved blood glucose levels after glucose injection and fasting hyperinsulinemia. Suppressed Akt/protein kinase B activity and glucose transporter 4 translocation in skeletal muscle in high-fat diet mice were improved by pyridoxamine treatment. It appears that the antioxidative effect of pyridoxamine is associated with improvement of glucose intolerance and obesity in C57BL/6J mice fed a high-fat diet. We assume that pyridoxamine may be useful in the treatment of the obesity-associated metabolic syndrome.

Pleiotropic effect of pyridoxamine on diabetic complications via CD36 expression in KK-Ay/Ta mice.

AIM: Pyridoxamine inhibits the development of diabetic complications. CD36 is a receptor/transporter which binds fatty acids of lipoproteins. The objective of the present study was to examine the pleiotropic effects of pyridoxamine, especially CD36 expression in KK-A(y)/Ta mice with type 2 diabetic nephropathy. METHODS: KK-A(y)/Ta mice were divided into 2 groups as follows: pyridoxamine treatment group and a tap water group as controls. The urinary ACR, fasting serum insulin, TG and lipoprotein subclasses were measured as biochemical parameters. The renal expressions of malondialdehyde (MDA) were evaluated by immunohistochemistry. CD36 mRNA expressions in kidney and adipose tissue were also evaluated using real-time PCR. RESULTS: Pyridoxamine decreased levels of urinary ACR, serum TG, especially VLDL and fasting serum insulin. MDA accumulation in the pyridoxamine treated group was significantly lower than those in the non-treatment group. The CD36 accumulation and mRNA expressions in kidney and adipose tissue in the treatment group were significantly higher than those in the non-treatment group. CONCLUSIONS: It appears that pyridoxamine ameliorated lipid peroxidation and insulin resistance in KK-A(y)/Ta mice. This pleiotropic effect of pyridoxamine was related to CD36 expression in the kidney and adipose tissue.

Increased serum endogenous secretory receptor for advanced glycation end-product (esRAGE) levels in type 2 diabetic patients with decreased renal function.

BACKGROUND: The binding of advanced glycation end-products (AGEs) to their receptor for AGEs (RAGE) may play an important role in the development of diabetic vascular complications. Recently, soluble RAGE (sRAGE) has been identified as an alternative splicing form of RAGE. Furthermore, administration of sRAGE improved atherosclerosis in type 2 diabetic mice. OBJECTIVE: The objective of the present study is to investigate the role of endogenous secretory RAGE (esRAGE) as a biological marker for type 2 diabetic nephropathy, and also to determine whether serum esRAGE levels are associated with serum AGEs [including Nepsilon-(carboxymethyl) lysine-protein adducts (CML) and pentosidine] levels. MATERIALS AND METHODS: Serum esRAGE levels were examined in 107 type 2 diabetic patients including those on hemodialysis (HD). Diabetic patients were divided into three groups as follows: Group A [patients without nephropathy, i.e. normoalbuminuric stage (AER<30microg/mg creatinine)], Group B [patients with nephropathy (AER>30microg/mg creatinine) but excluding HD patients], and Group C (HD patients). RESULTS: Serum esRAGE and AGEs (including CML and pentosidine) levels in Group C were significantly higher than in Group A or B. In single linear univariate correlation, serum esRAGE levels were correlated using body mass index (BMI), duration of diabetes, and serum creatinine, high-density lipoprotein (HDL)-cholesterol and AGEs (including CML and pentosidine) levels. Furthermore, in stepwise multivariate regression analysis, the levels of serum creatinine and duration of diabetes were independently associated with serum esRAGE levels. CONCLUSION: Serum esRAGE levels are associated with the severity of renal dysfunction and duration of diabetes in type 2 diabetic patients.

Effect of pitavastatin on type 2 diabetes mellitus nephropathy in KK-Ay/Ta mice.

It is generally considered that 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitors (statins) have renoprotective effects via a pathway independent of their cholesterol-lowering cascade. In the kidneys of diabetic nephropathy, monomeric endothelial nitric oxide synthase (eNOS) is thought to be overexpressed; and its dimerization is suppressed. In the present study, we investigated the expression of eNOS and oxidative stress in type 2 diabetes mellitus KK-Ay/Ta mice treated with pitavastatin, one of the statins. The KK-Ay/Ta mice were divided into 3 groups and given pitavastatin intraperitoneally starting at 8 weeks of age for 8 weeks: pitavastatin 3 mg/(kg d) (n=5), pitavastatin 10 mg/(kg d) (n=5), and a control group (n=10). The urinary albumin-creatinine ratio (ACR), urinary 8-hydroxy-2'-deoxyguanosine, body weight, fasting blood glucose, hemoglobin A1c, total cholesterol, and triglyceride were measured; and the intraperitoneal glucose tolerance test was performed. The eNOS, nitrotyrosine, and p47 phox were evaluated by immunohistochemical analyses and/or Western blot analyses. Guanosine triphosphate cyclohydrolase 1 messenger RNA expression in the kidneys was evaluated using a real-time polymerase chain reaction assay. Pitavastatin improved the levels of urinary ACR and 8-hydroxy-2'-deoxyguanosine, intraperitoneal glucose tolerance test, and hemoglobin A1c. Protein levels of monomeric eNOS, nitrotyrosine, and p47 phox in the kidneys were decreased in the pitavastatin-treated groups. Guanosine triphosphate cyclohydrolase 1 messenger RNA expression was significantly increased in the pitavastatin groups. There were no significant changes in body weight, levels of fasting blood glucose, serum total cholesterol, triglyceride, and blood pressure among all groups. Pitavastatin improved urinary ACR apparently because of suppression of eNOS uncoupling and its antioxidant effect in the kidneys of KK-Ay/Ta mice.

Relationship between abdominal fat accumulation and insulin resistance in hemodialysis patients.

It is well known that obesity and insulin resistance are closely related to the development of type 2 diabetes. However, the exact pathogenic mechanism underlying the insulin resistance in renal disease has not been clarified. The purpose of the present study was to clarify the contribution of abdominal (visceral and subcutaneous) fat accumulation to insulin resistance and various clinical parameters, including C-reactive protein (CRP), in hemodialysis (HD) patients. Visceral and subcutaneous fat areas (VFA and SFA) were evaluated at the umbilical level by CT. Insulin resistance was estimated by the homeostasis model assessment-insulin resistance index (HOMA-IR) in 80 HD patients. Insulin resistance and CRP seemed to be closely correlated with fat-related parameters such as body mass index (BMI), VFA and SFA. HOMA-IR was positively correlated with BMI, VFA, SFA, triglycerides (TG), remnant-like particle (RLP)-cholesterol and CRP in simple regression analysis. In multiple stepwise regression analysis, SFA and RLP-cholesterol were predominant determinants of HOMA-IR in HD patients. Furthermore, CRP was positively correlated with BMI, VFA, SFA, TG, high-density lipoprotein (HDL)-cholesterol, atherosclerosis index (AI), immunoreactive insulin (IRI) and HOMA-IR in simple regression analysis. In multiple stepwise regression analysis, VFA and HDL-cholesterol were predominant determinants of CRP in HD patients. In conclusion, insulin resistance and CRP were related to fat-related parameters such as BMI, VFA and SFA in HD patients. Furthermore, the contribution of SFA to insulin resistance was much higher than that of VFA, while the opposite relation was recognized for CRP.