CiteULike: jyuh's Okada

Clinical features of non-diabetic renal diseases in patients with type 2 diabetes.

A Tone — 2008-07-06T16:09:18-00:00

Diabetes research and clinical practice, Vol. 69, No. 3. (September 2005), pp. 237-242.

Although persistent proteinuria is characteristic of diabetic nephropathy (DN), it is important to differentiate non-diabetic renal diseases (NDRD) in diabetic patients with proteinuria. In order to re-evaluate the indications for renal biopsy in the diabetic patients, we retrospectively analyzed the relationship between clinical features and histological diagnosis in 97 Japanese patients with type 2 diabetes manifesting overt proteinuria. Renal biopsy was performed because they were clinically suspected to have NDRD. Patients were divided into three groups according to the histological diagnosis: (1) the DN group (n=35) had only diabetic lesions, (2) the complicated group (n=16) had histological changes of NDRD superimposed on DN and (3) the non-DN group (n=46) had NDRD without diabetic lesions. We evaluated the specificity and sensitivity of four clinical parameters (duration of diabetes, presence or absence of diabetic retinopathy, microscopic hematuria and granular casts as urinary sediments) for the prediction of NDRD. Short duration of diabetes (<5 years) showed high sensitivity (75%) and specificity (70%). Diabetic retinopathy showed the highest sensitivity (87%) and specificity (93%). The sensitivity and specificity of microscopic hematuria (56 and 58%) and granular casts (68 and 47%) were lower. Our study confirmed that the absence of retinopathy and short duration of diabetes are useful clinical indications for renal biopsy in diabetic patients with overt proteinuria.

Association between markers of glycemic control, cardiovascular complications and survival in type 2 diabetic patients with end-stage renal disease.

T Okada — 2008-07-05T03:36:28-00:00

Internal medicine (Tokyo, Japan), Vol. 46, No. 12. (2007), pp. 807-814.

BACKGROUND AND OBJECTIVE: The influence of glycemic control on cardiovascular (CV) complications or survival is not clear in diabetic patients with end-stage renal disease (ESRD). Although glycohemoglobin (HbA1c) is widely used as a marker of hyperglycemia in these patients, it may be unreliable because of shortened erythrocyte lifespan. Glycated albumin (GA) is an alternative marker. We investigated the relation between these markers and development of CV complications or survival in diabetic ESRD patients. PATIENTS AND METHODS: We obtained three variables as markers of glycemic control: 1) mean HbA1c levels during 1-year after initiation of dialysis (HbA1c1), 2) mean HbA1c levels during 3 months from August to October 2002 (HbA1c2), 3) GA on October 2002 (GA2) from 78 type 2 diabetic patients on chronic hemodialysis. We examined the influence of these variables on survival or development of CV diseases using the multivariate Cox proportional-hazards models until September 2006. RESULTS: The 3-year survival rate was 73%. A total of 27 patients died, 15 from CV diseases. A total of 23 CV diseases developed in 20 patients. Neither HbA1c1 nor HbA1c2 was associated with all-cause mortality, CV mortality or development of CV diseases. GA2 was also not associated with mortality. However, the higher GA2 group (GA > or = 23.0%) had a significantly higher rate of development of CV diseases than the lower GA2 group (GA < 23.0%) (log-rank test p=0.03). The higher GA2 group was significantly associated with development of CV diseases relative to the lower GA2 group (hazard ratio 3.25, p=0.04). CONCLUSION: Neither HbA1c levels nor GA levels, at initiation of dialysis or on chronic dialysis, predicted mortality in diabetic ESRD patients. However, poor glycemic control as reflected by higher GA levels may be associated with the development of CV diseases. More studies are needed to clarify the beneficial effect of glycemic control in these patients.

Mapping quantitative trait loci for proteinuria-induced renal collagen deposition

N Kato — 2008-07-05T03:29:42-00:00

Kidney Int, Vol. 73, No. 9. (27 February 2008), pp. 1017-1023.

Nutritional management of dialysis patients: balancing among nutrient intake, dialysis dose, and nutritional status.

T Nakao — 2008-06-29T06:46:44-00:00

American journal of kidney diseases : the official journal of the National Kidney Foundation, Vol. 41, No. 3 Suppl 1. (March 2003)

BACKGROUND: Recommended protein intake for dialysis patients is much higher compared with allowance for normal adults. The authors tried to make a consideration on balancing among nutrient intake, dialysis dose, and nutritional status in maintenance dialysis patients. METHODS: In 57 patients, 13 on hemodialysis (HD) and 44 on continuous ambulatory peritoneal dialysis (CAPD), serum urea nitrogen (SUN), albumin, weekly creatinine clearance of CAPD, and body protein mass by multifrequency bioelectrical impedance analysis were measured. Energy intake was examined from the patients' food diary by a registered dietitian, and protein intake was estimated by both the patients' food diary and calculation of protein equivalent nitrogen appearance. RESULTS: In HD patients, predialysis SUN levels significantly correlated with the amounts of protein intake (r = 0.893; P < 0.001), and there was no correlation between post- and next predialysis SUN levels. In CAPD patients, SUN levels significantly correlated with the amounts of protein intake (r = 0.645; P < 0.001), and there was no correlation between SUN levels and weekly Ccr. The amounts of protein intake were significantly correlated with body protein mass (r = 0.365; P = 0.014), and there were significantly positive relationships between the amounts of protein intake and energy intake in both HD (r = 0.798; P < 0.001) and CAPD patients (r = 0.631; P = 0.006). CONCLUSION: Whereas higher intake of protein requires higher doses of dialysis, lower intake of protein with sufficient energy intake requires lower doses of dialysis, and both could give the same effects on nutritional status.

Identification and characterization of a fibroblast marker: FSP1.

F Strutz — 2006-11-02T22:46:44-00:00

J Cell Biol, Vol. 130, No. 2. (July 1995), pp. 393-405.

We performed subtractive and differential hybridization for transcript comparison between murine fibroblasts and isogenic epithelium, and observed only a few novel intracellular genes which were relatively specific for fibroblasts. One such gene encodes a filament-associated, calcium-binding protein, fibroblast-specific protein 1 (FSP1). The promoter/enhancer region driving this gene is active in fibroblasts but not in epithelium, mesangial cells or embryonic endoderm. During development, FSP1 is first detected by in situ hybridization after day 8.5 as a postgastrulation event, and is associated with cells of mesenchymal origin or of fibroblastic phenotype. Polyclonal antiserum raised to recombinant FSP1 protein stained the cytoplasm of fibroblasts, but not epithelium. Only occasional cells stain with specific anti-FSP1 antibodies in normal parenchymal tissue. However, in kidneys fibrosing from persistent inflammation, many fibroblasts could be identified in interstitial sites of collagen deposition and also in tubular epithelium adjacent to the inflammatory process. This pattern of anti-FSP1 staining during tissue fibrosis suggests, as a hypothesis, that fibroblasts in some cases arise, as needed, from the local conversion of epithelium. Consistent with this notion that FSP1 may be involved in the transition from epithelium to fibroblasts are experiments in which the in vitro overexpression of FSP1 cDNA in tubular epithelium is accompanied by conversion to a mesenchymal phenotype, as characterized by a more stellate and elongated fibroblast-like appearance, a reduction in cytokeratin, and new expression of vimentin. Similarly, tubular epithelium submerged in type I collagen gels exhibited the conversion to a fibroblast phenotype which includes de novo expression of FSP1 and vimentin. Use of the FSP1 marker, therefore, should further facilitate both the in vivo studies of fibrogenesis and the mapping of cell fate among fibroblasts.

Quantitative colocalization analysis of multicolor confocal immunofluorescence microscopy images: pushing pixels to explore biological phenomena.

V Zinchuk — 2008-05-10T00:36:11-00:00

Acta histochemica et cytochemica, Vol. 40, No. 4. (30 August 2007), pp. 101-111.

Quantitative colocalization analysis is an advanced digital imaging tool to examine antigens of interest in immunofluorescence images obtained using confocal microscopes. It employs specialized algorithms to estimate the degree of overlap of fluorescence signals and thus enables acquiring important new information not otherwise obtainable using qualitative approaches alone. As raw confocal images have high levels of background, they should be prepared to become suitable for reliable calculation of colocalization coefficients by correcting it. We provide concise theoretical basis of quantitative colocalization analysis, discuss its limitations, and describe proper use of the technique. The use of quantitative colocalization analysis is demonstrated by studying bile salt export pump and multidrug resistance associated protein 2 in the liver and major basic protein and platelet activating factor receptor antigens in conjunctiva. The review is focused on the applicability and correct interpretation of the results of colocalization coefficients calculations.

Is serum albumin a good marker for malnutrition in the physically impaired elderly?

M Kuzuya — 2008-04-17T09:28:02-00:00

Clinical nutrition (Edinburgh, Scotland), Vol. 26, No. 1. (February 2007), pp. 84-90.

BACKGROUND AND AIMS: Although serum albumin is well known as a marker of nutritional status, it has remained unclear whether impaired physical function affects serum albumin concentrations in older people. We examined whether hypoalbuminemia can be used as a marker of malnutrition in elderly subjects with various levels of physical impairment. METHODS: A total of 262 elderly subjects without acute illness were enrolled from various geriatric settings. For the nutritional assessment, serum albumin, total cholesterol, anthropometric measurements, and subjective global assessment (SGA) were determined. Physical function was evaluated by rating score of activity of daily living (ADL). RESULTS: As a whole, participants' serum albumin levels correlated with various nutritional parameters including anthropometric measurements and levels of serum total cholesterol as well as the SGA evaluation. However, after adjusting for age and gender, serum albumin levels in participants with a low ADL function did not correlate with nutritional parameters. Approximately 80% participants with low ADL function who were evaluated as being well nourished according to SGA evaluation had serum albumin levels lower than 35 g/l. CONCLUSIONS: The utility of serum albumin and the traditional cutoff (35 g/l) in older people with low ADL function is questionable even among those without inflammation.

Body protein index based on bioelectrical impedance analysis is a useful new marker assessing nutritional status: applications to patients with chronic renal failure on maintenance dialysis.

T Nakao — 2008-04-16T13:28:21-00:00

Contributions to nephrology, Vol. 155 (2007), pp. 18-28.

BACKGROUND: Evaluation and monitoring of nutritional status is a fundamental concept in providing nutritional care to patients with end-stage renal failure. There have been, however, few practically available indices assessing whole body protein stores of patients. METHODS: We enrolled 448 end-stage renal disease patients, 394 on maintenance hemodialysis (HD) and 54 on continuous ambulatory peritoneal dialysis (PD) in this study. 83 Age- and sex-matched subjects (controls) whose creatinine clearance was more than 70 ml/min and urinary protein excretion was less than 1.0 g/day were also recruited for comparison. To assess whole body somatic protein stores, we devised the body protein index (BPI). The volume of body protein mass was measured by multifrequency bioelectrical impedance analysis and then BPI was calculated as body protein mass (kg) divided by height in meters (m2). Based on BPI, we defined the nutritional status of the patients as normal if the value was within -10% of the mean value of control subjects, -10 to -14% as mild malnutrition, -15 to -19% as moderate malnutrition, and <-20% as severe malnutrition. RESULTS: The required time for measurement was 5.2 +/- 1.3 min and coefficient of variation of measurements was 0.8 +/- 0.2%. Among men the mean BPI in both HD and PD patients was significantly lower than those of control subjects (4.25 +/- 0.37, 4.38 +/- 0.34 vs. 4.72 +/- 0.37 kg/m2, p < 0.001). In women, BPI was significantly lower in HD patients than in control subjects (3.65 +/- 0.34 vs. 4.00 +/- 0.34 kg/m2, p < 0.033), whereas only a nonsignificant lower tendency was found in PD patients (3.83 +/- 0.39 kg/m2, p = 0.067). There were no significant differences in BPI values between diabetic and non-diabetic subjects, both in men (4.26 +/- 0.41 vs. 4.25 +/- 0.36 kg/m2) and women (3.69 +/- 0.36 vs. 3.65 +/- 0.34 kg/m2). Based on BPI nutritional categories, 113 (28.7%) of all HD patients were classified as having mild malnutrition, 57 (14.5%) as having moderate malnutrition, 40 (10.1%) as having severe malnutrition, and 184 (46.7%) were classified as normal. The patients of longer dialysis history groups showed a tendency of lower BPI compared to those of shorter dialysis history groups (p < 0.05), although the ages of the patients of the two groups did not significantly differ. No correlations were found between BPI and serum albumin or transferrin concentrations. Only weak correlations were found with albumin in male and transferrin in female HD patients. CONCLUSION: BPI calculated from measurement of multifrequency bioelectrical impedance analysis could evaluate whole body somatic protein stores, and is a potentially useful new marker assessing nutritional status in patients with chronic renal failure. Decreased body somatic protein stores, mainly due to muscle wasting, was prevalent in end-stage renal failure patients on maintenance dialysis.

Association of dietary intake of soy, beans, and isoflavones with risk of cerebral and myocardial infarctions in Japanese populations: the Japan Public Health Center-based (JPHC) study cohort I.

Y Kokubo — 2008-03-28T04:02:07-00:00

Circulation, Vol. 116, No. 22. (27 November 2007), pp. 2553-2562.

BACKGROUND: Soy and isoflavones have been proposed to reduce the risk of cardiovascular risk factors, but their potential as preventatives for cardiovascular disease remains uncertain. We investigated the association of soy and isoflavone intake with risk of cerebral and myocardial infarctions (CI and MI). METHODS AND RESULTS: To examine the association of soy and isoflavone intake with the risk of CI and MI, we studied 40,462 Japanese (40 to 59 years old, without cardiovascular disease or cancer at baseline). They completed a food-frequency questionnaire (1990-1992) and received follow-up to 2002. After 503,998 person-years of follow-up, we documented incidence of CI (n=587) and MI (n=308) and of mortality for CI and MI combined (n=232). For women, the multivariable hazard ratios and 95% confidence limits for soy intake > or = 5 times per week versus 0 to 2 times per week were 0.64 (0.43 to 0.95) for risk of CI, 0.55 (0.26 to 1.09) for risk of MI, and 0.31 (0.13 to 0.74) for cardiovascular disease mortality. Similar but weaker inverse associations were observed between intake of miso soup and beans and risk of cardiovascular disease mortality. The multivariable hazard ratios for the highest versus the lowest quintiles of isoflavones in women were 0.35 (0.21 to 0.59) for CI, 0.37 (0.14 to 0.98) for MI, and 0.87 (0.29 to 2.52) for cardiovascular disease mortality. An inverse association between isoflavone intake and risk of CI and MI was observed primarily among postmenopausal women. No significant association of dietary intake of soy, miso soup, and beans and isoflavones with CI or MI was present in men. CONCLUSIONS: High isoflavone intake was associated with reduced risk of CI and MI in Japanese women. The risk reduction was pronounced for postmenopausal women.

High glucose up-regulates lipopolysaccharide-stimulated inflammatory cytokine production via c-jun N-terminal kinase in the monocytic cell line THP-1.

H Iwata — 2008-02-24T01:23:00-00:00

J Endotoxin Res, Vol. 13, No. 4. (2007), pp. 227-234.

Diabetic subjects are susceptible to atherosclerosis. It has been postulated that inflammation plays a crucial role in atherogenesis. Since previous studies suggested persistent low-grade infection by Gram-negative bacteria such as Chlamydia spp. and/or periodontal infection is associated with increased atherogenesis among diabetic subjects, we hypothesized that macrophages under hyperglycemia respond to lipopolysaccharide (LPS) challenge in a more exaggerated manner than under normal glucose conditions. Therefore, we examined cytokine productivity and associated signal transduction molecules in LPS-stimulated the monocytic cell line THP-1, under conditions of hyperglycemia. Differentiated THP-1 cells were cultured under normal and high glucose conditions without fetal bovine serum, and were stimulated with Escherichia coli LPS in the presence of LPS binding protein. Following stimulation, activated signal transduction molecules were detected by protein microarray and confirmed thereafter. Results indicated that c-jun N-terminal kinase (JNK) was highly-phosphorylated at high glucose concentrations, and this was confirmed by Western-immunoblotting. Tumor necrosis factor-alpha and monocyte chemo-attractant protein-1 production were significantly enhanced under these conditions. SP600125, a selective inhibitor of JNK, dose-dependently suppressed the production of these cytokine. Therefore, we suggest that this may be one of the mechanisms by which sub-clinical infection by Gram-negative bacteria promotes atherosclerosis in diabetic subjects.

Expression and role of connexins in the rat renal vasculature

T Takenaka — 2008-02-04T02:52:33-00:00

Kidney Int, Vol. 73, No. 4. (28 November 2007), pp. 415-422.

Profiling of functional phosphodiesterase in mesangial cells using a CRE-SEAP-based reporting system.

Y Zhu — 2008-01-31T02:19:30-00:00

Br J Pharmacol, Vol. 148, No. 6. (July 2006), pp. 833-844.

1. Phosphodiesterases (PDEs) are critically implicated in the regulation of mesangial cell function, but profile of functional PDEs in mesangial cells is still unclear. In this study, we investigated roles of individual PDEs in the regulation of mesangial cell behavior by the cAMP pathway. 2. Reporter mesangial cells that express secreted alkaline phosphatase (SEAP) under the control of the cAMP response element (CRE) were exposed to selective PDE inhibitors in the presence or absence of cAMP, and activity of CRE, expression of CRE-regulated protein, mitogenesis and cell survival were examined. 3. Exposure of reporter cells to cAMP-elevating agents resulted in time- and concentration-dependent activation of CRE. Treatment of the cells with any PDE inhibitors alone did not induce CRE activation. Under stimulation with 8-bromo-cAMP or 8-bromo-cGMP, however, inhibitors of PDE2, PDE3, PDE4 and PDE5 enhanced activation of CRE. Inhibition of PDE1 or PDE6 did not affect the CRE activation. 4. Among different combinations tested, only inhibitors of PDE3 and PDE4 cooperatively increased the level of intracellular cAMP, activity of protein kinase A, activation of CRE, and CRE-regulated protein, connexin43. 5. Concomitant inhibition of PDE3 and PDE4 attenuated mitogen-induced activation of extracellular signal-regulated kinases and cell proliferation. Under serum deprivation, combinational inhibition of PDE3 and PDE4 exclusively caused activation of caspase-3 and apoptosis. 6. The present data elucidated that PDE3 and PDE4 play critical roles in the regulation of mesangial cell function. PDE3 and PDE4 were identified as the novel, antiapoptotic machinery that supports survival of mesangial cells.

Absence of Increased alpha1-Microglobulin in IgA Nephropathy Proteinuria

Hiroyuki Yokota — 2008-01-15T04:57:12-00:00

Mol Cell Proteomics, Vol. 6, No. 4. (1 April 2007), pp. 738-744.

To search for biomarkers of IgA nephropathy, protein profiles of urine samples from patients with IgA nephropathy and normal volunteers were compared using two-dimensional DIGE. Most of the 172 spots identified in the urine were serum proteins, and their amounts in IgA nephropathy urine were much higher than those in normal urine; this can be explained as proteinuria caused by glomerular dysfunction. However, only alpha1-microglobulin, also one of the major serum proteins, in IgA nephropathy urine was not higher in amount than that in normal urine. We confirmed using ELISA analysis that the amounts of transferrin and albumin in IgA nephropathy and diabetic nephropathy urine were much higher than those in normal urine, whereas the amount of alpha1-microglobulin in IgA nephropathy urine was not higher than that in normal urine and was much lower than that in diabetic nephropathy urine. Approximately 50% of alpha1-microglobulin forms a complex with IgA in serum. These results suggest that alpha1-microglobulin in IgA nephropathy urine is a characteristic protein and might be a biomarker for IgA nephropathy and that alpha1-microglobulin might have a relationship with IgA nephropathy pathology. 10.1074/mcp.M600336-MCP200

A Possible Anti-Inflammatory Role of Angiotensin II Type 2 Receptor in Immune-Mediated Glomerulonephritis during Type 1 Receptor Blockade

Okada — 2006-10-24T00:00:14-00:00

American Journal of Pathology, Vol. 169, No. 5. (1 November 2006), pp. 1577-1589.

Methotrexate prevents renal injury in experimental diabetic rats via anti-inflammatory actions.

K Yozai — 2008-01-14T15:30:44-00:00

J Am Soc Nephrol, Vol. 16, No. 11. (November 2005), pp. 3326-3338.

Recent studies suggested the involvement of inflammatory processes in the pathogenesis of diabetic nephropathy. Methotrexate (MTX), a folic acid antagonist, is widely used for the treatment of inflammatory diseases. Recently, it has been shown that treatment with low-dose MTX reduces the cardiovascular mortality in patients with rheumatoid arthritis, suggesting that MTX has anti-atherosclerotic effects via its anti-inflammatory actions. This study was designed to determine the anti-inflammatory effects of this agent on diabetic nephropathy. Diabetes was induced in Sprague-Dawley rats with streptozotocin, and MTX (0.5 or 1.0 mg/kg) was administered once a week for 8 wk. Treatment with MTX reduced urinary albumin excretion, mesangial matrix expansion, macrophage infiltration, expression of TGF-beta and type IV collagen, and intercellular adhesion molecule-1 in glomeruli. MTX also reduced the high glucose-induced NF-kappaB activation in vitro and in vivo. The results indicate that intermittent administration of MTX prevented renal injuries without changes in blood glucose level and BP in experimental diabetic rats. The protective effects of MTX are suggested to be mediated by its anti-inflammatory actions through inhibition of NF-kappaB activation and consequent reduction of intercellular adhesion molecule-1 expression and macrophage infiltration. The results suggest that anti-inflammatory agents might be beneficial for the treatment of diabetic nephropathy.

Thiazolidinedione ameliorates renal injury in experimental diabetic rats through anti-inflammatory effects mediated by inhibition of NF-kappaB activation.

S Ohga — 2008-01-14T15:08:27-00:00

Am J Physiol Renal Physiol, Vol. 292, No. 4. (April 2007)

Thiazolidinedione (TZD), a ligand for peroxisome proliferator-activated receptor-gamma (PPAR-gamma), exerts anti-inflammatory effects independently of the insulin-sensitizing effect. In the present study, we tested the hypothesis that TZD prevents the progression of diabetic nephropathy by modulating the inflammatory process. Five-week-old Sprague-Dawley rats were divided into three groups: 1) nondiabetic control rats (non-DM), 2) diabetic rats (DM), and 3) diabetic rats treated with pioglitazone (DM+pio). Diabetes was induced by injection with streptozotocin (STZ). The DM+pio group received 0.0002% pioglitazone mixed in chow for 8 wk after induction of diabetes. Blood glucose and HbA1c were elevated in diabetic rats but did not change by treatment with pioglitazone. Pioglitazone reduced urinary albumin excretion and glomerular hypertrophy, suppressed the expression of transforming growth factor (TGF)-beta, type IV collagen, and ICAM-1, and infiltration of macrophages in the kidneys of diabetic rats. Furthermore, renal NF-kappaB activity was increased in diabetic rats and reduced by pioglitazone. PPAR-gamma was expressed in glomerular endothelial cells in the diabetic kidney and in cultured glomerular endothelial cells. High-glucose conditions increased the expression of ICAM-1 and the activation of NF-kappaB in cultured glomerular endothelial cells. These changes were reduced by pioglitazone, ciglitazone, and pyrrolidine dithiocarbamate, an inhibitor of NF-kappaB. However, pioglitazone did not show the changes in the presence of PPAR-gamma antagonist GW9662. Our results suggest that the preventive effects of pioglitazone may be mediated by its anti-inflammatory actions, including inhibition of NF-kappaB activation, ICAM-1 expression, and macrophage infiltration in the diabetic kidney.

Erythromycin ameliorates renal injury via anti-inflammatory effects in experimental diabetic rats.

A Tone — 2008-01-14T15:08:36-00:00

Diabetologia, Vol. 48, No. 11. (November 2005), pp. 2402-2411.

AIMS/HYPOTHESIS: Recent studies have shown that the inflammatory process is involved in the pathogenesis of diabetic nephropathy. Fourteen-membered ring macrolides, including erythromycin, have anti-inflammatory, as well as antibacterial effects. The aim of this study was to investigate the renoprotective effects of erythromycin in streptozotocin (STZ)-induced diabetic rats. METHODS: STZ-induced diabetic rats were treated orally with erythromycin (5 mg/kg body weight) or vehicle every day for 8 weeks. To evaluate the effect of erythromycin treatment, we measured urinary albumin excretion, and examined the following in the kidney: histological changes, the expression of intercellular adhesion molecule-1 (ICAM-1), macrophage infiltration, and nuclear factor-kappa B (NF-kappaB) activity. RESULTS: Erythromycin significantly reduced urinary albumin excretion without affecting blood glucose levels and blood pressure. Erythromycin also attenuated glomerular hypertrophy, mesangial expansion, macrophage infiltration and ICAM-1 expression in renal tissues. The expression of the gene encoding TGFB1 (also known as TGF-beta1), type IV collagen protein production and NF-kappaB activity in renal tissues were increased in diabetic rats and reduced by erythromycin treatment. CONCLUSIONS/INTERPRETATION: Erythromycin prevented renal injuries without changes of blood glucose levels and blood pressure in experimental diabetic rats. These results suggest that the renoprotective effects of erythromycin are based on its anti-inflammatory effect via suppression of NF-kappaB activation. Modulation of microinflammation with erythromycin may provide a new approach for diabetic nephropathy.

Macrophage scavenger receptor-a-deficient mice are resistant against diabetic nephropathy through amelioration of microinflammation.

HK Usui — 2007-10-21T14:14:11-00:00

Diabetes, Vol. 56, No. 2. (February 2007), pp. 363-372.

Microinflammation is a common major mechanism in the pathogenesis of diabetic vascular complications, including diabetic nephropathy. Macrophage scavenger receptor-A (SR-A) is a multifunctional receptor expressed on macrophages. This study aimed to determine the role of SR-A in diabetic nephropathy using SR-A-deficient (SR-A(-/-)) mice. Diabetes was induced in SR-A(-/-) and wild-type (SR-A(+/+)) mice by streptozotocin injection. Diabetic SR-A(+/+) mice presented characteristic features of diabetic nephropathy: albuminuria, glomerular hypertrophy, mesangial matrix expansion, and overexpression of transforming growth factor-beta at 6 months after induction of diabetes. These changes were markedly diminished in diabetic SR-A(-/-) mice, without differences in blood glucose and blood pressure levels. Interestingly, macrophage infiltration in the kidneys was dramatically decreased in diabetic SR-A(-/-) mice compared with diabetic SR-A(+/+) mice. DNA microarray revealed that proinflammatory genes were overexpressed in renal cortex of diabetic SR-A(+/+) mice and suppressed in diabetic SR-A(-/-) mice. Moreover, anti-SR-A antibody blocked the attachment of monocytes to type IV collagen substratum but not to endothelial cells. Our results suggest that SR-A promotes macrophage migration into diabetic kidneys by accelerating the attachment to renal extracellular matrices. SR-A may be a key molecule for the inflammatory process in pathogenesis of diabetic nephropathy and a novel therapeutic target for diabetic vascular complications.

Crucial role of a long-chain fatty acid elongase, Elovl6, in obesity-induced insulin resistance

Takashi Matsuzaka — 2007-10-07T05:08:59-00:00

Nat Med, Vol. 13, No. 10. (October 2007), pp. 1193-1202.

Galectin-9 inhibits glomerular hypertrophy in db/db diabetic mice via cell-cycle-dependent mechanisms.

M Baba — 2007-09-17T09:25:49-00:00

J Am Soc Nephrol, Vol. 16, No. 11. (November 2005), pp. 3222-3234.

Galectins are beta-galactoside-binding lectins that are involved in various biologic processes, such as apoptosis, cell proliferation, and cell-cycle regulation. Galectin-9 (Gal-9) was identified previously and demonstrated to have apoptotic potential to thymocytes in mice and activated CD8(+) T cells in nephrotoxic serum nephritis model. In this study, the effect of Gal-9 on G1-phase cell-cycle arrest, one of the hallmark pathologic changes in early diabetic nephropathy, was investigated. Eight-week-old male db/db mice received injections of recombinant Gal-9 or vehicle for 8 wk. The injection of Gal-9 into db/db mice significantly inhibited glomerular hypertrophy and mesangial matrix expansion and reduced urinary albumin excretion. Gal-9 reduced glomerular expression of TGF-beta1 and the number of p27(Kip1)- and p21(Cip1)-positive cells in glomeruli. Double staining with nephrin and type IV collagen revealed that podocytes were mainly positive for p27(Kip1). For further confirming the cell-cycle regulation by Gal-9, conditionally immortalized mouse podocyte cells were cultured under 5.5 and 25 mM d-glucose supplemented with Gal-9. Cell-cycle distribution analyses revealed that Gal-9 maintained further progression of cell cycle from the G1 phase. Gal-9 reversed the high-glucose-mediated upregulation of p27(Kip1) and p21(Cip1) and inhibited cell-cycle-dependent hypertrophy, i.e., reduced [(3)H]proline incorporation. The data suggest that Gal-9 plays a central role in inducing their successful progression from G1 to G2 phase by suppressing glomerular expression of TGF-beta1 and inhibition of cyclin-dependent kinase inhibitors. Gal-9 may give an impetus to develop new therapeutic tools targeted toward diabetic nephropathy.

Thiazolidinediones ameliorate diabetic nephropathy via cell cycle-dependent mechanisms.

T Okada — 2007-09-17T09:25:38-00:00

Diabetes, Vol. 55, No. 6. (June 2006), pp. 1666-1677.

Thiazolidinediones are ligands for peroxisome proliferator-activated receptor (PPAR)-gamma, widely used as insulin sensitizer in type 2 diabetic patients and implicated in apoptosis, cell proliferation, and cell cycle regulation. Here, the effect of thiazolidinediones on G1-phase cell cycle arrest, the hallmark in diabetic nephropathy, was investigated. Eight-week-old male Otsuka Long-Evans Tokushima fatty rats were treated with pioglitazone (1 mg x kg body wt(-1) x day(-1)) until 50 weeks of age and compared with insulin treatment. Although similar HbA(1c) levels were observed in both groups, pioglitazone significantly inhibited glomerular hypertrophy and mesangial matrix expansion and reduced urinary albumin excretion compared with the insulin-treated group. In addition, pioglitazone significantly reduced the number of glomerular p27(Kip1)-positive cells. Because prominent expression of PPAR-gamma was observed in podocytes in glomeruli and cultured cells, conditionally immortalized mouse podocyte cells were cultured under 5.5 and 25 mmol/l D-glucose supplemented with pioglitazone. Pioglitazone inhibited cell hypertrophy revealed by [(3)H]thymidine and [(3)H]proline incorporation, and pioglitazone reversed high glucose-induced G1-phase cell cycle arrest, i.e., an increase in G0/G1 phase and decrease in S and G2 phases. Pioglitazone suppressed high glucose-induced phosphorylation of p44/42 mitogen-activated protein kinase and reduced Bcl-2 and p27(Kip1) protein levels. Besides glucose-lowering action, pioglitazone ameliorates diabetic nephropathy via cell cycle-dependent mechanisms.

Role of advanced glycation end products in adynamic bone disease in patients with diabetic nephropathy.

T Yamamoto — 2007-08-29T08:20:44-00:00

Am J Kidney Dis, Vol. 38, No. 4 Suppl 1. (October 2001)

Adynamic bone disease and elevated serum levels of advanced glycation end products (AGEs) often are found in patients with renal failure caused by diabetic nephropathy. To clarify the role of AGEs in adynamic bone disease, we investigated the effect of these substances on cultured human osteoblasts and parathyroid cells. After 72 hours of incubation with AGEs-bovine serum albumin (BSA) (1,000 microgram/mL), there was significant inhibition of the synthesis of type I collagen and osteocalcin in response to stimulation with 10(-10) to 10(-8) M of 1,25-dihydroxycholecalciferol. In a human osteoblastic cell line (MG 63), AGEs-BSA did not affect human osteocalcin promoter activity. In human parathyroid cells, a receptor for AGEs was detected by reverse-transcriptase polymerase chain reaction. Incubation with AGEs-BSA for 48 hours significantly inhibited parathyroid hormone secretion in response to a low calcium concentration of 0.81 mM (P < 0.01). In HEK-293 cells, expressing calcium-sensing receptors, the same AGE concentration caused a significant potentiation of the extracellular Ca(2+) induced-intracellular calcium concentration after 24 and 48 hours of incubation (P < 0.05 and P < 0.01). These data suggest that AGEs are involved in the pathogenesis of adynamic bone disease by inhibiting osteoblastic activity and by inhibiting parathyroid hormone secretion in response to hypocalcemia.

Glycated albumin is a better glycemic indicator than glycated hemoglobin values in hemodialysis patients with diabetes: effect of anemia and erythropoietin injection.

M Inaba — 2007-08-24T03:05:28-00:00

J Am Soc Nephrol, Vol. 18, No. 3. (March 2007), pp. 896-903.

The significance of glycated albumin (GA), compared with casual plasma glucose (PG) and glycated hemoglobin (HbA(1c)), was evaluated as an indicator of the glycemic control state in hemodialysis (HD) patients with diabetes. The mean PG, GA, and HbA(1c) levels were 164.5 +/- 55.7 mg/dl, 22.5 +/- 7.5%, and 5.85 +/- 1.26%, respectively, in HD patients with diabetes (n = 538), which were increased by 51.5, 31.6, and 17.7%, respectively, compared with HD patients without diabetes (n = 828). HbA(1c) levels were significantly lower than simultaneous PG and GA values in those patients in comparison with the relationship among the three parameters in patients who had diabetes without renal dysfunction (n = 365), as reflected by the significantly more shallow slope of regression line between HbA(1c) and PG or GA. A significant negative correlation was found between GA and serum albumin (r = -0.131, P = 0.002) in HD patients with diabetes, whereas HbA(1c) correlated positively and negatively with hemoglobin (r = 0.090, P = 0.036) and weekly dose of erythropoietin injection (r = -0.159, P < 0.001), respectively. Although PG and GA did not differ significantly between HD patients with diabetes and with and without erythropoietin injection, HbA(1c) levels were significantly higher in patients without erythropoietin. Categorization of glycemic control into arbitrary quartile by HbA(1c) level led to better glycemic control in a significantly higher proportions of HD patients with diabetes than those assessed by GA. Multiple regression analysis demonstrated that the weekly dose of erythropoietin, in addition to PG, emerged as an independent factor associated with HbA(1c) in HD patients with diabetes, although PG but not albumin was an independent factor associated with GA. In summary, it is suggested that GA provides a significantly better measure to estimate glycemic control in HD patients with diabetes and that the assessment of glycemic control by HbA(1c) in these patients might lead to underestimation likely as a result of the increasing proportion of young erythrocyte by the use of erythropoietin.

Connective tissue growth factor mediates the profibrotic effects of transforming growth factor-beta produced by tubular epithelial cells in response to high glucose.

T Kobayashi — 2007-07-25T04:47:21-00:00

Clin Exp Nephrol, Vol. 9, No. 2. (June 2005), pp. 114-121.

BACKGROUND: It was reported that connective tissue growth factor (CTGF) was expressed in the tubular epithelial cells of the diabetic kidney. CTGF has, among other factors, been implicated in mediating the downstream, profibrotic effects of transforming growth factor-beta (TGF-beta), though is precise role in interstitial fibrogenesis in the diabetic kidney has not yet been clarified. METHODS: We employed a coculture system involving cultured murine proximal tubular epithelial cells (mProx24) and renal fibroblasts (TFB), as a model of the subepithelial mesenchyme in the kidney in order to examine the profibrotic effects of CTGF derived from mProx24 cells in response to high glucose (30 mM). RESULTS: We showed that glucose stimulated CTGF expression in cultured mProx24 in both a dose- and a time-dependent manner, and that this effect was mediated by increased levels of TGF-beta. We also found that high glucose significantly stimulated TFB cells to produce profibrotic molecules, such as type I collagen, the EIIIA isoform of fibronectin, and plasminogen activator inhibitor-1. The induction of these molecules was both direct and indirect, the latter induction being mediated by mProx24 cell-derived CTGF, which, in turn, was induced by TGF-beta that was produced by the mProx24 cells. CONCLUSIONS: CTGF plays an important role in mediating renal interstitial fibrogenesis in response to high glucose and, as such, is a reasonable target for anti-fibrotic therapy.

Connective tissue growth factor expressed in tubular epithelium plays a pivotal role in renal fibrogenesis.

H Okada — 2007-07-25T04:47:00-00:00

J Am Soc Nephrol, Vol. 16, No. 1. (January 2005), pp. 133-143.

Connective tissue growth factor (CTGF) is one of the candidate factors that are thought to mediate the downstream profibrotic action of TGF-beta. However, its precise role in renal interstitial fibrogenesis has not yet been clarified. It was demonstrated previously that CTGF was expressed in tubular epithelial cells that had been engulfed by interstitial fibrosis in the remnant kidney of the subtotal nephrectomy (SNx) model. In the present study, co-cultures of tubular epithelial cells (mProx24) and tubulointerstitial fibroblasts (TFB) that mimic the subepithelial mesenchyme in the kidney were used to study the profibrotic effects of TGF-beta1-induced CTGF. In these co-cultures, TGF-beta1 treatment resulted in significantly increased mRNA levels of type I collagen and fibronectin in the TFB. These effects were both direct and indirect, with the latter being mediated by CTGF derived from the co-cultured mProx24. Then TGF-beta1 transgenic mice were subtotally nephrectomized and treated with CTGF antisense oligodeoxynucleotide, and their kidneys were analyzed for fibrosis. Intravenous administration of CTGF antisense oligodeoxynucleotide significantly blocked CTGF expression in the proximal tubular epithelial cells in the remnant kidney of these animals despite the sustained level of TGF-beta1 mRNA. This reduction in CTGF mRNA level paralleled a reduction in mRNA levels of matrix molecules as well as proteinase inhibitors plasminogen activator inhibitor-1 and tissue inhibitor of metalloproteinase-1, suppressing renal interstitial fibrogenesis. In conclusion, tubular CTGF acts as a downstream mediator of the profibrotic effects of TGF-beta1 in the remnant kidney, which is a promising target for antifibrotic drugs designed to treat TGF-beta1-dependent interstitial fibrosis.

Early role of Fsp1 in epithelial-mesenchymal transformation.

H Okada — 2007-07-25T03:37:37-00:00

Am J Physiol, Vol. 273, No. 4 Pt 2. (October 1997)

A seamless plasticity exists among cells shifting between epithelial and mesenchymal phenotypes during early development and again later, in adult tissues, following wound repair or organ remodeling in response to injury. Fsp1, a gene encoding a fibroblast-specific protein associated with mesenchymal cell morphology and motility, is expressed during epithelial-mesenchymal transformations (EMT) in vivo. In the current study, we identified several cytokines that induce Fsp1 in cultured epithelial cells. A combination of these factors, however, was most efficacious at completing the process of EMT. The optimal combination identified were two of the cytokines classically associated with fibrosis, i.e., transforming growth factor-beta1 (TGF-beta1) and epidermal growth factor (EGF). To confirm that it was the induction of Fsp1 by these cytokines mediating EMT, we used antisense oligomers to block Fsp1 production and subsequently measured cell motility and markers of EMT phenotype. The antisense oligomers suppressed Fsp1 expresison and epithelial transformation; therefore, we conclude that the appearance of Fsp1 is an important early event in the pathway toward EMT.

Spironolactone prevents early renal injury in streptozotocin-induced diabetic rats.

G Fujisawa — 2007-07-25T01:04:15-00:00

Kidney Int, Vol. 66, No. 4. (October 2004), pp. 1493-1502.

BACKGROUND: Glomerular and tubulointerstitial injury leads to chronic impairment of renal function, and thus, reversal of the injury may improve renal function and survival. The present study investigated whether and how mineralocorticoid receptor antagonist spironolactone ameliorates early renal injury in streptozotocin-induced diabetic rats. METHODS: Streptozotocin (65 mg/kg, single intraperitoneal injection)- or vehicle-administered rats were used as diabetic or control rats, respectively. The streptozotocin-administered rats were treated with spironolactone (50 mg/kg/day sc) for 3 weeks. Among the 3 groups of rats, we compared renal fibrosis and renal hypertrophy, using picro-sirius red staining and immunohistochemistry of ED-1 macrophage marker, plasminogen activator inhibitor-1 (PAI-1), and transforming growth factor (TGF)-beta1. RESULTS: Three weeks after administration of streptozotocin, rats exhibited increased collagen deposition in glomerular, tubulointerstitial, and perivascular areas in the kidney, which was completely attenuated by spironolactone treatment. In rats given streptozotocin alone, there were increases in ED-1-positive cell, PAI-1 expression, and TGF-beta1 expression in glomeruli and tubulointerstitiums, which were also suppressed by spironolactone treatment. Maximal glomerular and proximal tubular areas were not significantly different among the 3 groups. Rats given streptozotocin alone revealed an increase in proximal tubule wall-to-lumen ratio that was not influenced by treatment with spironolactone. CONCLUSION: Streptozotocin-induced renal fibrosis, PAI-1 expression, TGF-beta1 expression, and macrophage infiltration occur via mineralocorticoid receptor, and spironolactone ameliorates renal fibrosis presumably via the inhibition of macrophage infiltration, PAI-1 expression, and TGF-beta1 expression in streptozotocin-induced early diabetic injury.