Overexpression of acetyl CoA carboxylase ß exacerbates podocyte injury in the kidney of streptozotocin-induced diabetic mice.

A single nucleotide polymorphism (SNP) within the acetyl CoA carboxylase (ACC) ß gene (ACACB), rs2268388, has been shown to be associated with susceptibility to development of proteinuria in patients with type 2 diabetes. To investigate the biological roles of ACCß in the pathogenesis of diabetic nephropathy, we examined the effects of overexpression of ACACB using podocyte-specific ACACB-transgenic mice or ACACB-overexpressing murine podocytes. Podocyte-specific ACACB-transgenic mice or littermate mice were treated with streptozotocin (STZ) to induce diabetes, and 12 weeks after induction of diabetes, we examined the expression of podocyte markers to evaluate the degree of podocyte injury in these mice. We also examined the effects of ACCß on podocyte injury in ACACB- or LacZ-overexpressing murine podocytes. Podocyte-specific ACACB overexpression did not cause visible podocyte injury in non-diabetic mice. In STZ-induced diabetic mice, ACACB-transgenic mice showed a significant increase in urinary albumin excretion, accompanied by decreased synaptopodin expression and podocin mislocalization in podocytes, compared with wild-type mice. In cultured murine podocytes, overexpression of ACACB significantly decreased synaptopodin expression and reorganized stress fibers under high glucose conditions, but not in normal glucose conditions. The decrease of synaptopodin expression and reorganized stress fibers observed in ACACB overexpressing cells cultured under high glucose conditions was reversed by a treatment of 5-aminoimidazole-4-carboxamide-1-beta-4-ribofuranoside (AICAR), activator of AMP-activated protein kinase (AMPK). The excess of ACCß might contribute to exacerbation of podocyte injury in the kidney of an animal model for diabetes mellitus, and the AMPK/ACCß pathway may be a novel therapeutic target for the prevention of diabetes-related podocyte injury.

Fatty acids are novel nutrient factors to regulate mTORC1 lysosomal localization and apoptosis in podocytes.

Podocyte apoptosis is a potent mechanism of proteinuria in diabetic nephropathy. More detailed mechanistic insight into podocyte apoptosis is needed to better understand the pathogenesis of diabetic nephropathy. An elevated level of serum free fatty acid (FFA), as well as hyperglycemia, is a clinical characteristic in diabetes, although its causal role in podocyte apoptosis remains unclear. This study examined the effect of three types of FFAs, saturated, monounsaturated and polyunsaturated FFAs, on podocyte apoptosis. Palmitate, a saturated FFA, induced endoplasmic reticulum (ER) stress-dependent apoptosis in podocytes. Oleate, a monounsaturated FFA, and eicosapentaenoic acid (EPA), an ω-3 polyunsaturated FFA did not induce apoptosis; rather, they antagonized palmitate-induced apoptosis. Palmitate activated mammalian target of rapamycin (mTOR) complex 1 (mTORC1), a nutrient-sensing kinase regulating a wide range of cell biology. Furthermore, inhibition of mTORC1 activity by rapamycin or siRNA for Raptor, a component of mTORC1, ameliorated palmitate-induced ER stress and apoptosis in podocytes. Activity of mTORC1 is regulated by upstream kinases and Rag/Ragulator-dependent recruitment of mTOR onto lysosomal membranes. Palmitate activated mTORC1 by enhancing recruitment of mTOR onto lysosomal membranes, which was inhibited by co-incubation with oleate or EPA. Inhibition of mTOR translocation onto lysosomes by transfection with dominant-negative forms of Rag ameliorated palmitate-induced apoptosis. This study suggests that saturated and unsaturated FFAs have opposite effects on podocyte apoptosis by regulating mTORC1 activity via its translocation onto lysosomal membranes, and the results provide a better understanding of the pathogenesis in diabetic nephropathy and a novel role of mTORC1 in cell apoptosis.

Altered unfolded protein response is implicated in the age-related exacerbation of proteinuria-induced proximal tubular cell damage.

Aging is a dominant risk factor for end-stage renal disease. We analyzed the mechanism involved in age-related exacerbation of proteinuria-induced proximal tubular cell (PTC) damage by focusing on endoplasmic reticulum-related unfolded protein response (UPR). After equal-degree induction of proteinuria in 24-month-old (aged) and 3-month-old (young) mice by intraperitoneal free fatty acid-bound albumin overload, tubulointerstitial lesions were more severe in aged than in young mice. In aged PTCs, proteinuria-induced cell-adaptive UPR resulting from induction of the molecular chaperone BiP was significantly suppressed, whereas proapoptotic UPR with CHOP overexpression was enhanced. Treatment with the exogenous molecular chaperone tauroursodeoxycholic acid (TUDCA) ameliorated proteinuria-induced tubulointerstitial lesions and PTC apoptosis in aged mice. Among the three UPR branches, alterations in the inositol-requiring 1α (IRE1α) pathway, but not the activating transcription factor 6 or PERK pathway, were associated with impaired BiP induction in aged kidneys. Moreover, siRNA-mediated suppression of BiP and IRE1α exacerbated free fatty acid-bound albumin-induced apoptosis in cultured PTCs, whereas siRNA-mediated CHOP suppression ameliorated apoptosis. Finally, proteinuria-induced BiP induction in PTCs was diminished in kidney specimens from elderly patients. These results indicate that maladaptive UPRs are involved in proteinuria-induced tubulointerstitial lesions exacerbation in aged kidneys, and that supplementation of chaperones may be used to treat elderly patients with persistent proteinuria. These results should improve understanding of cell vulnerability in aged kidneys.

Safety and efficacy of skin patches containing loxoprofen sodium in diabetic patients with overt nephropathy.

BACKGROUND: Because oral nonsteroidal anti-inflammatory drugs (NSAIDs) have adverse effects on kidney function, patients with kidney diseases are administered these drugs as transdermal patches. Little is known about the effects of NSAID patches on renal function. We therefore assessed the effects of topical loxoprofen sodium on kidney function in type 2 diabetic patients with overt nephropathy. METHODS: Twenty patients with type 2 diabetes and overt proteinuria and with knee and/or low back pain were treated with skin patches containing 100 mg loxoprofen on the knee or back for 24 h per day for 5 consecutive days. The degree of pain was assessed using a visual analogue scale (VAS). Blood and 24-h urine samples were obtained at baseline and at the end of the study. Glomerular filtration rate (GFR) was estimated from serum creatinine and cystatin C concentrations. RESULTS: The 20 patients consisted of 11 males and 9 females, of mean age 61.6 ± 13.9 years. Loxoprofen-containing patches significantly reduced VAS pain without affecting blood pressure, GFR or urinary prostaglandin E2 concentration. Serum concentrations of loxoprofen and its active trans-OH metabolite did not correlate with GFR. CONCLUSIONS: Loxoprofen-containing patches do not affect renal function in type 2 diabetic patients with overt nephropathy over a short-term period. Long-term studies are needed to clarify the safety of loxoprofen-containing patches in patients with chronic kidney diseases.

Obesity-mediated autophagy insufficiency exacerbates proteinuria-induced tubulointerstitial lesions.

Obesity is an independent risk factor for renal dysfunction in patients with CKDs, including diabetic nephropathy, but the mechanism underlying this connection remains unclear. Autophagy is an intracellular degradation system that maintains intracellular homeostasis by removing damaged proteins and organelles, and autophagy insufficiency is associated with the pathogenesis of obesity-related diseases. We therefore examined the role of autophagy in obesity-mediated exacerbation of proteinuria-induced proximal tubular epithelial cell damage in mice and in human renal biopsy specimens. In nonobese mice, overt proteinuria, induced by intraperitoneal free fatty acid-albumin overload, led to mild tubular damage and apoptosis, and activated autophagy in proximal tubules reabsorbing urinary albumin. In contrast, diet-induced obesity suppressed proteinuria-induced autophagy and exacerbated proteinuria-induced tubular cell damage. Proximal tubule-specific autophagy-deficient mice, resulting from an Atg5 gene deletion, subjected to intraperitoneal free fatty acid-albumin overload developed severe proteinuria-induced tubular damage, suggesting that proteinuria-induced autophagy is renoprotective. Mammalian target of rapamycin (mTOR), a potent suppressor of autophagy, was activated in proximal tubules of obese mice, and treatment with an mTOR inhibitor ameliorated obesity-mediated autophagy insufficiency. Furthermore, both mTOR hyperactivation and autophagy suppression were observed in tubular cells of specimens obtained from obese patients with proteinuria. Thus, in addition to enhancing the understanding of obesity-related cell vulnerability in the kidneys, these results suggest that restoring the renoprotective action of autophagy in proximal tubules may improve renal outcomes in obese patients.

Role of angiotensin II-mediated AMPK inactivation on obesity-related salt-sensitive hypertension.

Salt-sensitive hypertension is a characteristic of the metabolic syndrome. Given the links to cardiovascular events, the mechanisms underlying sodium metabolism may represent an important therapeutic target for this disorder. Angiotensin II (AII) is a key peptide underlying sodium retention. However, 5'AMP-activated protein kinase (AMPK) has also been reported to participate in the regulation of ion transport. In this study we examined the relationship between AII and AMPK on the development of hypertension in two salt-sensitive mouse models. In the first model, the mice were maintained on a high-fat diet (HFD) for 12 weeks, in order to develop features similar to the metabolic syndrome, including salt-sensitive hypertension. HFD-induced obese mice showed elevated systolic blood pressure and lower sodium excretion in response to salt loading, along with an increase in AII contents and inactivation of AMPK in the kidney, which were significantly improved by the treatment of an angiotensin II antagonist, losartan, for 2 weeks. To clarify the effects of AII, a second group of mice was infused with AII via an osmotic pump, which led to higher systolic blood pressure, and decreases in urinary sodium excretion and the expression of AMPK, in a manner similar to those observed in the HFD mice. However, treatment with an AMPK activator, metformin, improved the changes induced by the AII, suggesting that AII induced sodium retention works by acting on AMPK activity. Finally, we evaluated the changes in salt-sensitivity by performing 2-week salt loading experiments with or without metformin. AII infusion elevated blood pressure by salt loading but metformin prevented it. These findings indicate that AII suppresses AMPK activity in the kidney, leading to sodium retention and enhanced salt-sensitivity, and that AMPK activation may represent a new therapeutic target for obesity-related salt-sensitive hypertension.

Fructose induces tubulointerstitial injury in the kidney of mice.

Fructose induces several kinds of human metabolic disorders; however, information regarding fructose-induced kidney injury is still limited. This study examined fructose-induced kidney injury in mice and clarified the differential susceptibility of three mouse strains: C57Bl/6J, CBA/JN and DBA/2N. In this study all mice were fed with an equal calorie count for sixteen weeks to remove the influence of total energy intake from metabolic effects by fructose-feeding. Only DBA/2N mice, but not C57Bl/6J and CBA/JN mice, fed with fructose displayed tubulointerstitial fibrosis localized on the outer cortex of the kidney together with the increase of mRNA expression of Kim1 and Ngal in the absence of distinct glomerular lesions and albuminuria - decidedly different from diabetic nephropathy. In time-course study of DBA/2N mice fed with fructose diet, the inflammation and fibrosis in the outer cortex of the kidney were enhancing after eight weeks, in parallel with the accumulation of oxidative stress. This progression of renal damage in DBA/2N mice was accompanied with increasing mRNA expression of GLUT5. These results suggest that the responsiveness of GLUT5 expression to fructose at the kidney is one of pivotal roles for the progression of fructose-induced kidney injury.

Fenofibrate, a PPARα agonist, has renoprotective effects in mice by enhancing renal lipolysis.

As renal lipotoxicity can lead to chronic kidney disease (CKD), we examined the role of peroxisome proliferator-activated receptor (PPAR)-α, a positive regulator of renal lipolysis. Feeding mice a high-fat diet induced glomerular injury, and treating them with fenofibrate, a PPARα agonist, increased the expression of lipolytic enzymes and reduced lipid accumulation and oxidative stress in glomeruli, while inhibiting the development of albuminuria and glomerular fibrosis. In mice given an overload of free fatty acid-bound albumin to induce tubulointerstitial injury, fenofibrate attenuated the development of oxidative stress, macrophage infiltration, and fibrosis, and enhanced lipolysis in the renal interstitium. Fenofibrate inhibited palmitate-induced expression of profibrotic plasminogen activator inhibitor-1 (PAI-1) in cultured mesangial cells, and the expression of both monocyte chemoattractant protein-1 and PAI-1 in proximal tubular cells along with the overexpression of lipolytic enzymes. Thus, fenofibrate can attenuate lipotoxicity-induced glomerular and tubulointerstitial injuries, with enhancement of renal lipolysis. Whether amelioration of renal lipotoxicity by PPARα agonists will turn out to be a useful strategy against CKD will require direct testing.

Cerebral microvascular disease predicts renal failure in type 2 diabetes.

Abnormalities in small renal vessels may increase the risk of developing impaired renal function, but methods to assess these vessels are extremely limited. We hypothesized that the presence of small vessel disease in the brain, which manifests as silent cerebral infarction (SCI), may predict the progression of kidney disease in patients with type 2 diabetes. We recruited 608 patients with type 2 diabetes without apparent cerebrovascular or cardiovascular disease or overt nephropathy and followed them for a mean of 7.5 years. At baseline, 177 of 608 patients had SCI, diagnosed by cerebral magnetic resonance imaging. The risk for the primary outcome of ESRD or death was significantly higher for patients with SCI than for patients without SCI [hazard ratio, 2.44; 95% confidence interval (CI) 1.36 to 4.38]. The risk for the secondary renal end point of any dialysis or doubling of the serum creatinine concentration was also significantly higher for patients with SCI (hazard ratio, 4.79; 95% CI 2.72 to 8.46). The estimated GFR declined more in patients with SCI than in those without SCI; however, the presence of SCI did not increase the risk for progression of albuminuria. In conclusion, independent of microalbuminuria, cerebral microvascular disease predicted renal morbidity among patients with type 2 diabetes.

Oleate and eicosapentaenoic acid attenuate palmitate-induced inflammation and apoptosis in renal proximal tubular cell.

Free fatty acid (FFA)-bound albumin, which is filtrated through the glomeruli and reabsorbed into proximal tubular cells, is one of the crucial mediators of tubular damage in proteinuric kidney disease. In this study, we examined the role of each kind of FFA on renal tubular damage in vitro and tried to identify its molecular mechanism. In cultured proximal tubular cells, a saturated fatty acid, palmiate, increased the expression of monocyte chemoattractant protein-1 (MCP-1), but this effect was abrogated by co-incubation of monounsaturated fatty acid, oleate, or ω-3 polyunsaturated fatty acid, eicosapentaenoic acid (EPA). Palmitate led to intracellular accumulation of diacylglycerol (DAG) and subsequent activation of protein kinase C protein family. Among the several PKC inhibitors, rottlerin, a PKCθ inhibitor, prevented palmitate-induced MCP-1 expression via inactivation of NFB pathway. Overexpression of dominant-negative PKCθ also inhibited palmitate-induced activation of MCP-1 promoter. Furthermore, palmitate enhanced PKCθ-dependent mitochondrial apoptosis, which was also prevented by co-incubation with oleate or EPA through restoration of pro-survival Akt pathway. Moreover, oleate and EPA inhibited palmitate-induced PKCθ activation through the conversion of intracellular DAG to triglyceride with the restoration of diacylglycerol acyltransferase 2 expression. These results suggest that oleate and EPA have protective effects against the palmitate-induced renal tubular cell damage by inhibiting PKCθ activation.

Renoprotective effects of asialoerythropoietin in diabetic mice against ischaemia-reperfusion-induced acute kidney injury.

AIM: Diabetic patients are at higher risk of failure to recover after acute kidney injury, however, the mechanism and therapeutic strategies remain unclear. Erythropoietin is cytoprotective in a variety of non-haematopoietic cells. The aim of the present study was to clarify the mechanism of diabetes-related acceleration of renal damage after ischaemia-reperfusion injury and to examine the therapeutic potential of asialoerythropoietin, a non-haematopoietic erythropoietin derivative, against ischaemia-reperfusion-induced acute kidney injury in diabetic mice. METHODS: C57BL/6J mice with and without streptozotocin-induced diabetes were subjected to 30 min unilateral renal ischaemia-reperfusion injury at 1 week after induction of diabetes. They were divided into four group: (i) non-diabetic plus ischaemia-reperfusion injury; (ii) non-diabetic plus ischaemia-reperfusion injury plus asialoerythropoietin (3000 IU/kg bodyweight); (iii) diabetic plus ischaemia-reperfusion injury; and (iv) diabetic plus ischemia-reperfusion injury plus asialoerythropoietin. Experiments were conducted at the indicated time periods after ischaemia-reperfusion injury. RESULTS: Ischaemia-reperfusion injury of diabetic kidney resulted in significantly low protein expression levels of bcl-2, an anti-apoptotic molecule, and bone morphogenetic protein-7 (BMP-7), an anti-fibrotic and pro-regenerative factor, compared with non-diabetic kidneys. Diabetic kidney subsequently showed severe damage including increased tubular cell apoptosis, tubulointerstitial fibrosis and decreased tubular proliferation, compared with non-diabetic kidney. Treatment with asialoerythropoietin induced bcl-2 and BMP-7 expression in diabetic kidney and decreased tubular cell apoptosis, tubulointerstitial fibrosis and accelerated tubular proliferation. CONCLUSION: Reduced induction bcl-2 and BMP-7 may play a role in the acceleration of renal damage after ischaemia-reperfusion injury in diabetic kidney. The renoprotective effects of asialoerythropoietin on acute kidney injury may be mediated through the induction of bcl-2 and BMP-7.

Exendin-4 has an anti-hypertensive effect in salt-sensitive mice model.

The improvement of salt-sensitive hypertension is a therapeutic target for various vascular diseases. Glucagon-like peptide 1 (GLP-1), an incretin peptide, has been reported to have natriuretic effect as well as blood glucose lowering effect, although its exact mechanism and clinical usefulness remain unclear. Here, we examined anti-hypertensive effect of exendin-4, a GLP-1 analog, in salt-sensitive obese db/db mice and angiotensin II (angII)-infused C57BLK6/J mice. The treatment of exendin-4 for 12 weeks inhibited the development of hypertension in db/db mice. In db/db mice, the urinary sodium excretion was delayed and blood pressure was elevated in response to a high-salt load, whereas these were attenuated by exendin-4. In db/db mice, intra-renal angII concentration was increased. Furthermore, exendin-4 prevented angII-induced hypertension in non-diabetic mice and inhibited angII-induced phosphorylation of ERK1/2 in cultured renal cells. Considered together, our results indicate that exendin-4 has anti-hypertensive effects through the attenuation of angII-induced high-salt sensitivity.

Effects of high sodium intake and diuretics on the circadian rhythm of blood pressure in type 2 diabetic patients treated with an angiotensin II receptor blocker.

BACKGROUND: The inhibition of the renin-angiotensin system in the diabetic condition was reported to enhance the sodium sensitivity of blood pressure. In patients with sodium-sensitive hypertension, high sodium intake reduces the nocturnal fall in blood pressure. Therefore, we examined the effects of the amount of sodium intake or diuretics in patients with diabetes treated with an angiotensin receptor blocker. METHODS: We recruited 32 Japanese type 2 diabetic patients with base line blood pressure > or =130/80 mmHg and treated with valsartan (80 mg daily). At baseline, 24-h ambulatory blood pressure and 24-h urinary excretion of sodium were measured. The patients were then randomly assigned to take either combination therapy with 50 mg of losartan plus 12.5 mg of hydrochlorothiazide or monotherapy with 160 mg of valsartan for 24 weeks. RESULTS: At baseline, 22 of 32 (69%) patients were classified as non-dippers, and the night/day ratio of mean arterial pressure was significantly correlated with 24-h urinary sodium excretion. The combination therapy resulted in a significantly higher fall than the monotherapy in 24-h mean, daytime, night-time and morning blood pressures. The night/day ratio of mean arterial pressure was significantly reduced from the baseline at the end of the study in the combination therapy group, but not in the monotherapy group. In non-dipper patients, the diminished nocturnal fall in blood pressure was restored by the combination therapy. CONCLUSIONS: Excessive intake of salt causes non-dipping and diuretics restored nocturnal BP fall in type 2 diabetic patients treated with angiotensin 2 receptor blockers.

Asialoerythropoietin prevents contrast-induced nephropathy.

Strategies to prevent contrast-induced nephropathy (CIN) are suboptimal. Erythropoietin was recently found to be cytoprotective in a variety of nonhematopoietic cells, so it was hypothesized that the nonhematopoietic erythropoietin derivative asialoerythropoietin would prevent CIN. Nephropathy was induced in rats by injection of the radiocontrast medium Ioversol in addition to inhibition of prostaglandin and nitric oxide synthesis. Administration of a single dose of asialoerythropoietin before the induction of nephropathy significantly attenuated the resulting renal dysfunction and histologic renal tubular injury. Contrast-induced apoptosis of renal tubular cells was inhibited by asialoerythropoietin both in vivo and in vitro, and this effect was blocked by a Janus kinase 2 (JAK2) inhibitor in vitro. Furthermore, phospho-JAK2/signal transducer and activator of transcription 5 (STAT5) and heat-shock protein 70 increased after injection of asialoerythropoietin, suggesting that the effects of asialoerythropoietin may be mediated by the activation of the JAK2/STAT5 pathway. Overall, these findings suggest that asialoerythropoietin may have potential as a new therapeutic approach to prevent CIN given its ability to preserve renal function and directly protect renal tissue.

Insulin regulates SOCS2 expression and the mitogenic effect of IGF-1 in mesangial cells.

Renal hypertrophy and deposition of extracellular matrix proteins are consistent findings in diabetic nephropathy and these processes can be halted or reversed by euglycemic control. Using DNA microarray analysis of glomerular RNA from control and diabetic rats we found that the expression levels of insulin-like growth factor 1 receptor (IGF-1R) were increased while those of suppressor of cytokine signaling 2 (SOCS2) and STAT5 were decreased. All of these changes were normalized by islet cell transplantation. Overexpression of SOCS2 in rat mesangial cells inhibited IGF-1-induced activation of extracellular signal-regulated kinase, which subsequently reduced type IV collagen and DNA synthesis, an effect due to interaction of SOCS2 with IGF-1R. Inhibition of SOCS2 overexpression by small interfering RNA suppressed IGF-1R-mediated actions by preventing phosphorylation of tyrosine 317 in the p66Shc adaptor protein; however, overexpression of either SOCS1 or SOCS3 did not affect IGF-1R signaling. Insulin directly increased STAT5 and SOCS2 expression in mesangial cells. This study shows that insulin can inhibit the mitogenic action of IGF-1 in mesangial cells by regulating STAT5/SOCS2 expression. Insulin deficiency may contribute to the mesangial expansion found in diabetes through reduced STAT5/SOCS2 expression.

Reduction of diabetes-induced oxidative stress, fibrotic cytokine expression, and renal dysfunction in protein kinase Cbeta-null mice.

Diabetes induces the activation of several protein kinase C (PKC) isoforms in the renal glomeruli. We used PKC-beta(-/-) mice to examine the action of PKC-beta isoforms in diabetes-induced oxidative stress and renal injury at 8 and 24 weeks of disease. Diabetes increased PKC activity in renal cortex of wild-type mice and was significantly reduced (<50% of wild-type) in diabetic PKC-beta(-/-) mice. In wild-type mice, diabetes increased the translocation of PKC-alpha and -beta1 to the membrane, whereas only PKC-alpha was elevated in PKC-beta(-/-) mice. Increases in urinary isoprostane and 8-hydroxydeoxyguanosine, parameters of oxidative stress, in diabetic PKC-beta(-/-) mice were significantly reduced compared with diabetic wild-type mice. Diabetes increased NADPH oxidase activity and the expressions of p47(phox), Nox2, and Nox4 mRNA levels in the renal cortex and were unchanged in diabetic PKC-beta(-/-) mice. Increased expression of endothelin-1 (ET-1), vascular endothelial growth factor (VEGF), transforming growth factor (TGF)-beta, connective tissue growth factor (CTGF), and collagens IV and VI found in diabetic wild-type mice was attenuated in diabetic PKC-beta(-/-) mice. Diabetic PKC-beta(-/-) mice were protected from renal hypertrophy, glomerular enlargement, and hyperfiltration observed in diabetic wild-type mice and had less proteinuria. Lack of PKC-beta can protect against diabetes-induced renal dysfunction, fibrosis, and increased expressions of Nox2 and -4, ET-1, VEGF, TGF-beta, CTGF, and oxidant production.

Benidipine attenuates glomerular hypertension and reduces albuminuria in patients with metabolic syndrome.

Recent studies have shown that metabolic syndrome is associated with an increased risk for chronic kidney disease. We recently found that the prevalence of sodium-sensitive hypertension in patients with metabolic syndrome was significantly higher than that in patients with essential hypertension but without metabolic syndrome. We therefore assessed the effects of benidipine, a long-acting calcium channel blocker, on the sodium sensitivity of blood pressure and renal hemodymamics in 5 patients with metabolic syndrome. Glomerular hemodynamics were assessed using pressure-natriuresis curves, which were constructed by plotting the urinary excretion of sodium as a function of the mean arterial pressure, which was calculated as the mean of 48 values based on 24-h monitoring, during the intake of low (3 g NaCl daily) and relatively high (10 g NaCl daily) sodium diets. Under the relatively high sodium diet condition, benidipine significantly lowered systolic and diastolic blood pressure. The pressure-natriuresis curve was steeper after the administration of benidipine. Benidipine lowered glomerular capillary hydraulic pressure (P(GC)) levels (from 54.4+/-7.5 to 47.0+/-7.0 mmHg, p=0.0152) and reduced both the resistance of the afferent arterioles (from 10,338+/-2,618 to 9,026+/-2,627 dyn.s/cm5, p=0.047) and the resistance of the efferent arterioles (from 4,649+/-2,039 to 2,419+/-2,081 dyn.s/cm(5), p=0.003). The urinary albumin excretion rate also decreased after the administration of benidipine. These findings indicated that benidipine may be effective for reducing the risk of developing chronic kidney disease in patients with metabolic syndrome.

Iron status and the use of non-steroidal anti-inflammatory drugs in hemodialysis patients.

We examined whether the use of non-steroidal anti-inflammatory drugs (NSAIDs) can affect the anemia and iron status of hemodialysis patients. We recruited patients from six dialysis centers who had undergone maintenance hemodialysis for at least four months. We examined the use of NSAIDs during the past three months based on their medical records and assigned the patients to three groups (group A, non-NSAID group; group B, aspirin group; and group C, non-aspirin NSAID group). Of the 446 patients, 95 (21.3%) were treated with aspirin and 103 (23.1%) were treated with non-aspirin NSAIDs. The serum iron level and transferrin saturation (TSAT) were significantly lower in group C patients than those in group A. However, the ratio of the patients who were administrated iron preparations during the past three months was significantly higher than that in the other two groups. The incidences of positive fecal occult blood tests did not differ substantially between the three groups. The ratios of the patients who were administrated recombinant human erythropoietin were the same between three groups. Using a multiple regression analysis, the administration of non-aspirin NSAIDs was identified as an independent factor for the decreased serum iron and the decreased TSAT levels. A multiple logistic regression analysis revealed that the patients using non-aspirin NSAIDs had an increased the requirement for iron preparation therapy (OR 2.03, 95% CI, 1.28-3.22). The use of non-aspirin NSAIDs may therefore increase the risk of the iron deficiency in patients undergoing hemodialysis.

Polymorphisms of the protein kinase C-beta gene (PRKCB1) accelerate kidney disease in type 2 diabetes without overt proteinuria.

OBJECTIVE: We investigated the contribution of PKC-beta gene (PRKCB1) polymorphisms to diabetic kidney disease in a prospective observational follow-up study. RESEARCH DESIGN AND METHODS: A total of 364 Japanese subjects with type 2 diabetes without overt proteinuria were enrolled during 1996-1998 and followed until 2004. Five single nucleotide polymorphisms (-1504C/T, -546C/G, -348A/G, -278C/T, and -238C/G) in the promoter region of PRKCB1 were genotyped. The end points were transition from stage to stage of diabetic nephropathy as a time-to-event outcome and the annual decline rate of estimated glomerular filtration rate (eGFR) as a slope-based outcome. RESULTS: During the study (median 6 years), 34 of 364 subjects (9.3%) progressed. Kaplan-Meier estimation revealed that subjects with both T allele at -1054 C/T and G allele at -546 C/G polymorphisms frequently showed transition to advanced stages of diabetic nephropathy (P = 0.015). The annual change rate in eGFR in the subjects with both alleles was also significantly higher than in others (-2.96 +/- 0.62 vs. -1.63 +/- 0.15 ml/min per 1.73 m(2)/year, P = 0.02). The estimated frequency of this risk T-G haplotype was significantly higher in the progressors who showed transition to advanced nephropathy stages (12%) than in the nonprogressors (5%) (odds ratio 2.3 [95% CI 1.0-5.2]), and it was also higher in those with accelerated decline of the Delta eGFR (> or =3 ml/min per 1.73 m(2)/year) than in those without (2.1 [1.1-3.9]). CONCLUSIONS: Our study indicates that PRKCB1 is a predictor for worsening of kidney disease in Japanese subjects with type 2 diabetes.

Factors associated with frequent remission of microalbuminuria in patients with type 2 diabetes.

To estimate the frequency of remission/regression of microalbuminuria and to identify factors affecting such outcomes in Japanese patients with type 2 diabetes, we observed 216 patients with type 2 diabetes and microalbuminuria enrolled during an initial 2-year evaluation period for the next 6 years. Remission was defined as shift to normoalbuminuria and regression as a 50% reduction in urinary albumin excretion rate (AER) from one 2-year period to the next. Reduction of urinary AER was frequent, with a 6-year cumulative incidence of 51% (95% CI 42-60) for remission and 54% (45-63) for regression, whereas the frequency of progression to overt proteinuria was 28% (19-37). Microalbuminuria of short duration, the use of renin-angiotensin system-blocking drugs, and lower tertiles for HbA(1c) (<6.95%) and systolic blood pressure (<129 mmHg) were independently associated with remission or regression in the pooled logistic regression analysis. The results indicate that reduction in urinary AER occurs frequently in Japanese patients with type 2 diabetes. Early detection of microalbuminuria and a multifactorial control may result in improved outcomes for diabetic nephropathy and cardiovascular events.