Improvement of blood glucose control in IDDM patients retards the progression of morphological changes in early diabetic nephropathy

Arteriolar hyalinosis is related to rapid GFR decline and long-standing GFR changes observed on renal biopsies in normo-microalbuminuric type 2 diabetic patients

AIMS

Whether or not renal structural changes, especially arteriolar hyalinosis, are related to the rate of renal functional decline and increase in urinary albumin excretion (UAE) at the early stage of diabetic nephropathy in patients with type 2 diabetes is still unknown. Our previous study determined that arteriolar hyalinosis is an independent risk factor for low GFR. We sought to determine whether arteriolar hyalinosis is also a risk factor for rapidly progressive decline in GFR.

METHODS

We evaluated 22 type 2 diabetic patients with normo- or microalbuminuria who took part in the previous study, to clarify which renal histological factors were associated with changes in UAE and the glomerular filtration rate (GFR) during 11.0 ± 3.0 years of follow-up. Light and electron microscopy-based morphometric analyses were performed to quantitatively evaluate the glomerular and interstitial structural changes.

RESULTS

In all 22 patients, the GFR was significantly decreased from baseline to follow-up, while the UAE did not change markedly between the 2 periods. After 11 ± 3 years of follow-up, the GFR was significantly lower in the rapid decliner group (annual rate of GFR decline ≥3.0%) than in the non-rapid decliner group (p = 0.017). The index of arteriolar hyalinosis (IAH) at baseline in the rapid decliners was significantly larger than in the non-rapid decliners (p = 0.015). The IAH showed a significant negative correlation with the GFR at follow-up (r = 0.50, p = 0.018) and the annual rate in the GFR decline (r = 0.47, p = 0.027) and significant positive correlations with UAE at follow-up (r = 0.46, p = 0.034) and the annual rate in the UAE increase (r = 0.57, p = 0.005). The GFR at follow-up in patients with IAH ≥2.0 was significantly decreased from baseline (p = 0.042) and significantly lower than that of the patients with IAH <2.0 (p = 0.026), which did not decrease significantly from baseline. The frequency of rapid decliners was larger in the IAH ≥2.0 than in the IAH <2.0 patients (p = 0.037).

CONCLUSIONS

Aggravated arteriolar hyalinosis was a risk factor for a rapid GFR decline. This finding might reflect initial changes in early diabetic nephropathy.

Serial renal biopsies in normo- and microalbuminuric patients with type 2 diabetes demonstrate that loss of renal function is associated with a reduction in glomerular filtration surface secondary to mesangial expansion

AIMS

The aim of the present study was to explore the relationship between changes in renal structure in patients with type 2 diabetes at an early stage of diabetic nephropathy using serial renal biopsies, and change in renal function.

METHODS

The study population comprised 10 patients with type 2 diabetes with normo- or microalbuminuria at baseline. Light and electron microscopy-based morphometric analyses were performed to quantitatively evaluate glomerular and interstitial structural changes. Urinary albumin excretion (UAE) and glomerular filtration rate (GFR) were measured annually. A second renal biopsy was performed after a mean of 6.1 ± 2.4 years of follow-up.

RESULTS

UAE, GFR, blood pressure and severity of diabetic retinopathy (DR) did not change between the baseline and follow-up. The annual decrease in the surface density of the peripheral glomerular basement membrane (GBM) (Sv[PGBM/glom]) was correlated with the rate of loss of GFR during the six-year follow-up period. The annual change in the Sv(PGBM/glom) was negatively correlated with the change in mesangial volume fraction.

CONCLUSIONS

Decreases in the GFR in patients with type 2 diabetes with normo- or microalbuminuria at baseline were associated with a decreased glomerular filtration surface, as a result of mesangial expansion during a mean six years of observation. These findings confirm ongoing pathological progression of glomerulopathy despite no significant change in albuminuria or retinopathy status.

Insulin and glucose-lowering agents for treating people with diabetes and chronic kidney disease

BACKGROUND

Diabetes is the commonest cause of chronic kidney disease (CKD). Both conditions commonly co-exist. Glucometabolic changes and concurrent dialysis in diabetes and CKD make glucose-lowering challenging, increasing the risk of hypoglycaemia. Glucose-lowering agents have been mainly studied in people with near-normal kidney function. It is important to characterise existing knowledge of glucose-lowering agents in CKD to guide treatment.

OBJECTIVES

To examine the efficacy and safety of insulin and other pharmacological interventions for lowering glucose levels in people with diabetes and CKD.

SEARCH METHODS

We searched the Cochrane Kidney and Transplant Register of Studies up to 12 February 2018 through contact with the Information Specialist using search terms relevant to this review. Studies in the Register are identified through searches of CENTRAL, MEDLINE, and EMBASE, conference proceedings, the International Clinical Trials Register (ICTRP) Search Portal and ClinicalTrials.gov.

SELECTION CRITERIA

All randomised controlled trials (RCTs) and quasi-RCTs looking at head-to-head comparisons of active regimens of glucose-lowering therapy or active regimen compared with placebo/standard care in people with diabetes and CKD (estimated glomerular filtration rate (eGFR) < 60 mL/min/1.73 m2) were eligible.

DATA COLLECTION AND ANALYSIS

Four authors independently assessed study eligibility, risk of bias, and quality of data and performed data extraction. Continuous outcomes were expressed as post-treatment mean differences (MD). Adverse events were expressed as post-treatment absolute risk differences (RD). Dichotomous clinical outcomes were presented as risk ratios (RR) with 95% confidence intervals (CI).

MAIN RESULTS

Forty-four studies (128 records, 13,036 participants) were included. Nine studies compared sodium glucose co-transporter-2 (SGLT2) inhibitors to placebo; 13 studies compared dipeptidyl peptidase-4 (DPP-4) inhibitors to placebo; 2 studies compared glucagon-like peptide-1 (GLP-1) agonists to placebo; 8 studies compared glitazones to no glitazone treatment; 1 study compared glinide to no glinide treatment; and 4 studies compared different types, doses or modes of administration of insulin. In addition, 2 studies compared sitagliptin to glipizide; and 1 study compared each of sitagliptin to insulin, glitazars to pioglitazone, vildagliptin to sitagliptin, linagliptin to voglibose, and albiglutide to sitagliptin. Most studies had a high risk of bias due to funding and attrition bias, and an unclear risk of detection bias.Compared to placebo, SGLT2 inhibitors probably reduce HbA1c (7 studies, 1092 participants: MD -0.29%, -0.38 to -0.19 (-3.2 mmol/mol, -4.2 to -2.2); I2 = 0%), fasting blood glucose (FBG) (5 studies, 855 participants: MD -0.48 mmol/L, -0.78 to -0.19; I2 = 0%), systolic blood pressure (BP) (7 studies, 1198 participants: MD -4.68 mmHg, -6.69 to -2.68; I2 = 40%), diastolic BP (6 studies, 1142 participants: MD -1.72 mmHg, -2.77 to -0.66; I2 = 0%), heart failure (3 studies, 2519 participants: RR 0.59, 0.41 to 0.87; I2 = 0%), and hyperkalaemia (4 studies, 2788 participants: RR 0.58, 0.42 to 0.81; I2 = 0%); but probably increase genital infections (7 studies, 3086 participants: RR 2.50, 1.52 to 4.11; I2 = 0%), and creatinine (4 studies, 848 participants: MD 3.82 μmol/L, 1.45 to 6.19; I2 = 16%) (all effects of moderate certainty evidence). SGLT2 inhibitors may reduce weight (5 studies, 1029 participants: MD -1.41 kg, -1.8 to -1.02; I2 = 28%) and albuminuria (MD -8.14 mg/mmol creatinine, -14.51 to -1.77; I2 = 11%; low certainty evidence). SGLT2 inhibitors may have little or no effect on the risk of cardiovascular death, hypoglycaemia, acute kidney injury (AKI), and urinary tract infection (low certainty evidence). It is uncertain whether SGLT2 inhibitors have any effect on death, end-stage kidney disease (ESKD), hypovolaemia, fractures, diabetic ketoacidosis, or discontinuation due to adverse effects (very low certainty evidence).Compared to placebo, DPP-4 inhibitors may reduce HbA1c (7 studies, 867 participants: MD -0.62%, -0.85 to -0.39 (-6.8 mmol/mol, -9.3 to -4.3); I2 = 59%) but may have little or no effect on FBG (low certainty evidence). DPP-4 inhibitors probably have little or no effect on cardiovascular death (2 studies, 5897 participants: RR 0.93, 0.77 to 1.11; I2 = 0%) and weight (2 studies, 210 participants: MD 0.16 kg, -0.58 to 0.90; I2 = 29%; moderate certainty evidence). Compared to placebo, DPP-4 inhibitors may have little or no effect on heart failure, upper respiratory tract infections, and liver impairment (low certainty evidence). Compared to placebo, it is uncertain whether DPP-4 inhibitors have any effect on eGFR, hypoglycaemia, pancreatitis, pancreatic cancer, or discontinuation due to adverse effects (very low certainty evidence).Compared to placebo, GLP-1 agonists probably reduce HbA1c (7 studies, 867 participants: MD -0.53%, -1.01 to -0.06 (-5.8 mmol/mol, -11.0 to -0.7); I2 = 41%; moderate certainty evidence) and may reduce weight (low certainty evidence). GLP-1 agonists may have little or no effect on eGFR, hypoglycaemia, or discontinuation due to adverse effects (low certainty evidence). It is uncertain whether GLP-1 agonists reduce FBG, increase gastrointestinal symptoms, or affect the risk of pancreatitis (very low certainty evidence).Compared to placebo, it is uncertain whether glitazones have any effect on HbA1c, FBG, death, weight, and risk of hypoglycaemia (very low certainty evidence).Compared to glipizide, sitagliptin probably reduces hypoglycaemia (2 studies, 551 participants: RR 0.40, 0.23 to 0.69; I2 = 0%; moderate certainty evidence). Compared to glipizide, sitagliptin may have had little or no effect on HbA1c, FBG, weight, and eGFR (low certainty evidence). Compared to glipizide, it is uncertain if sitagliptin has any effect on death or discontinuation due to adverse effects (very low certainty).For types, dosages or modes of administration of insulin and other head-to-head comparisons only individual studies were available so no conclusions could be made.

AUTHORS' CONCLUSIONS

Evidence concerning the efficacy and safety of glucose-lowering agents in diabetes and CKD is limited. SGLT2 inhibitors and GLP-1 agonists are probably efficacious for glucose-lowering and DPP-4 inhibitors may be efficacious for glucose-lowering. Additionally, SGLT2 inhibitors probably reduce BP, heart failure, and hyperkalaemia but increase genital infections, and slightly increase creatinine. The safety profile for GLP-1 agonists is uncertain. No further conclusions could be made for the other classes of glucose-lowering agents including insulin. More high quality studies are required to help guide therapeutic choice for glucose-lowering in diabetes and CKD.

Continuous subcutaneous insulin infusion: short-term benefits apparent, long-term benefits speculative

Continuous subcutaneous insulin infusion (CSII) is increasingly used as a means of insulin delivery for those with type 1 diabetes, and has recently been endorsed by NICE for this purpose. CSII improves glycaemic control compared to other intensified insulin regimens, with a small decrease in HbA1C and mean blood glucose, and a larger reduction in glucose fluctuation. This improved control is not associated with an increased risk of hypoglycaemia and CSII probably results in significantly lower rates of severe hypoglycaemia. There is no evidence that those using CSII are at increased risk of diabetic ketoacidosis. CSII is uniquely associated with a small risk of application site infection. CSII has a positive impact on quality of life. There is much less evidence concerning the benefits of CSII in reducing microvascular or macrovascular complication rates. Small studies, mostly from the 1980s, show improvements in markers of early nephropathy, retinopathy progression and neuropathy, but the potential long-term impact of CSII has not been proven. Recently CSII has been used in the management of those Br J Diabetes Vasc Dis 2004;4:104—08 with type 2 diabetes but evidence is lacking with regard to the benefits of using it in this group.

Podocyte-specific Nox4 deletion affords renoprotection in a mouse model of diabetic nephropathy

AIMS/HYPOTHESIS

Changes in podocyte morphology and function are associated with albuminuria and progression of diabetic nephropathy. NADPH oxidase 4 (NOX4) is the main source of reactive oxygen species (ROS) in the kidney and Nox4 is upregulated in podocytes in response to high glucose. We assessed the role of NOX4-derived ROS in podocytes in vivo in a model of diabetic nephropathy using a podocyte-specific NOX4-deficient mouse, with a major focus on the development of albuminuria and ultra-glomerular structural damage.

METHODS

Streptozotocin-induced diabetes-associated changes in renal structure and function were studied in male floxedNox4 and podocyte-specific, NOX4 knockout (podNox4KO) mice. We assessed albuminuria, glomerular extracellular matrix accumulation and glomerulosclerosis, and markers of ROS and inflammation, as well as glomerular basement membrane thickness, effacement of podocytes and expression of the podocyte-specific protein nephrin.

RESULTS

Podocyte-specific Nox4 deletion in streptozotocin-induced diabetic mice attenuated albuminuria in association with reduced vascular endothelial growth factor (VEGF) expression and prevention of the diabetes-induced reduction in nephrin expression. In addition, podocyte-specific Nox4 deletion reduced glomerular accumulation of collagen IV and fibronectin, glomerulosclerosis and mesangial expansion, as well as glomerular basement membrane thickness. Furthermore, diabetes-induced increases in renal ROS, glomerular monocyte chemoattractant protein-1 (MCP-1) and protein kinase C alpha (PKC-α) were attenuated in podocyte-specific NOX4-deficient mice.

CONCLUSIONS/INTERPRETATION

Collectively, this study shows the deleterious effect of Nox4 expression in podocytes by promoting podocytopathy in association with albuminuria and extracellular matrix accumulation in experimental diabetes, emphasising the role of NOX4 as a target for new renoprotective agents.

Rs12976445 Polymorphism is Associated with Risk of Diabetic Nephropathy Through Modulating Expression of MicroRNA-125 and Interleukin-6R

BACKGROUND

Diabetic nephropathy (DN) is one of the most significant long-term complications of diabetes mellitus (DM), and it is a primary risk factor for end-stage renal disease. MicroRNAs (miRNAs) play important roles in regulating the expression of genes, including interleukin-6R (IL-6R), which has been reported to be involved in the development of DNDN. The aim of this study was to identify the dysregulation of miRNA and its target responsible for the development of DN in DM.

MATERIAL AND METHODS

We collected the kidney tissues from patients with DN (N=36) and control patients (N=28), and performed real-time PCR and Western blot analysis to determine the expression of IL-6R. Computational analysis and luciferase assay were used to identify the miRNA that regulates IL-6R. To explore the association between rs12976445 polymorphism and risk of DN, we enrolled 594 DM patients with (N=282) or without DN (N=312), and studied the association between a variant in miR-125a and risk of DN in DM.

RESULTS

The expression of IL-6R was barely detected in the control groups, while in the DN group, the IL-6R was clearly detectable. Next, miR-125a was identified as a regulator of IL-6R by using informatics analysis and luciferase assay. A single-nucleotide polymorphism (rs12976445) in pri-miR-125a has been shown to compromise the mature processing of miR-125a, and we showed that the expression levels of miR-125a was comparable between individuals carrying TT and CT, and when combined into 1 group, the miR-125a expression was approximately 3 times lower than in the CC group. We found significant differences regarding rs12976445 genotype distribution between the DN and the control (OR=1.45, 95% C.I.=1.02-2.08, p<0.05) with the possible confounding factors adjusted for by using logistic regression analysis.

CONCLUSIONS

We identified miR-125a as a direct regulator of IL-6R, and the genotype of rs12976445 might be a novel predictor of the development of DN in DM.

Cellular and molecular aspects of diabetic nephropathy; the role of VEGF-A

The prevalence of diabetes mellitus increased during the last century and it is estimated that 45% of the patients are not diagnosed. In South America the prevalence of diabetes and chronic kidney disease (CKD) increased, with a great disparity among the countries with respect to access to dialysis. In Ecuador it is one of the main causes of mortality, principally in the provinces located on the coast of the Pacific Ocean. The greatest single cause of beginning dialysis is diabetic nephropathy (DN). Even using the best therapeutic options for DN, the residual risk of proteinuria and of terminal CKD remains high. In this review we indicate the importance of the problem globally and in our region. We analyse relevant cellular and molecular studies that illustrate the crucial significance of glomerular events in DN development and evolution and in insulin resistance. We include basic anatomical, pathophysiological and clinical concepts, with special attention to the role of angiogenic factors such as the vascular endothelial growth factor (VEGF-A) and their relationship to the insulin receptor, endothelial isoform of nitric oxide synthase (eNOS) and angiopoietins. We also propose various pathways that have therapeutic potential in our opinion. Greater in-depth study of VEGF-A and angiopoietins, the state of glomerular VEGF resistance, the relationship of VEGF receptor 2/nephrin, VEGF/insulin receptors/nephrin and the relationship of VEGF/eNOS-NO at glomerular level could provide solutions to the pressing world problem of DN and generate new treatment alternatives.

Urinary excretion of neutrophil gelatinase-associated lipocalin in diabetic rats

Recent studies suggest that tubular damage precedes glomerular damage in the progression of diabetic nephropathy. Therefore, we evaluated oxidative stress and urinary excretion of tubular proteins as markers of tubular dysfunction. Methods. Diabetes was induced in rats by streptozotocin administration (50 mg/kg). Oxidative stress was assessed by measuring the activity of catalase (CAT), glutathione peroxidase (GPx), and superoxide dismutase (SOD); additionally, expression levels of 3-nitrotyrosine (3-NT), 4-hydroxynonenal (4-HNE), and oxidized protein (OP) were quantified. Whole glomerular filtration rate (GFR) was measured. Urinary excretion of neutrophil gelatinase-associated lipocalin (uNGAL), osteopontin (uOPN), and N-acetyl-β-D-glucosaminidase (uNAG) was also determined. Results. Diabetic rats showed an increase in uNGAL excretion 7 days following induction of diabetes. Diuresis, proteinuria, albuminuria, creatinine clearance, and GFR were significantly increased by 30 days after induction. Furthermore, there was an increase in both CAT and SOD activity, in addition to 3-NT, 4-HNE, and OP expression levels. However, GPx activity was lower. Serum levels of NGAL and OPN, as well as excretion levels of uNGAL, uOPN, and uNAG, were increased in diabetics. Tubular damage was observed by 7 days after diabetes induction and was further aggravated by 30 days after induction. Conclusion. The tubular dysfunction evidenced by urinary excretion of NGAL precedes oxidative stress during diabetes.

Gliquidone decreases urinary protein by promoting tubular reabsorption in diabetic Goto-Kakizaki rats

The efficacy of gliquidone for the treatment of diabetic nephropathy was investigated by implanting micro-osmotic pumps containing gliquidone into the abdominal cavities of Goto-Kakizaki (GK) rats with diabetic nephropathy. Blood glucose, 24 h urinary protein, and 24 h urinary albumin levels were measured weekly. After 4 weeks of gliquidone therapy, pathological changes in the glomerular basement membrane (GBM) were examined using an electron microscope. Real-time PCR, western blotting, and immunohistochemistry were employed to detect glomerular expression of receptors for advanced glycation end products (RAGE) (AGER), protein kinase C β (PKCβ), and protein kinase A (PKA) as well as tubular expression of the albumin reabsorption-associated proteins: megalin and cubilin. Human proximal tubular epithelial cells (HK-2 cells) were used to analyze the effects of gliquidone and advanced glycation end products (AGEs) on the expression of megalin and cubilin and on the absorption of albumin. Gliquidone lowered blood glucose, 24 h urinary protein, and 24 h urinary albumin levels in GK rats with diabetic nephropathy. The level of plasma C-peptide increased markedly and GBM and podocyte lesions improved dramatically after gliquidone treatment. Glomerular expression of RAGE and PKCβ decreased after gliquidone treatment, while PKA expression increased. AGEs markedly suppressed the expression of megalin and cubulin and the absorption of albumin in HK-2 cells in vitro, whereas the expression of megalin and cubilin and the absorption of albumin were all increased in these cells after gliquidone treatment. In conclusion, gliquidone treatment effectively reduced urinary protein in GK rats with diabetic nephropathy by improving glomerular lesions and promoting tubular reabsorption.

Comparative investigation of kidney mesangial cells from increased oxidative stress-induced diabetic rats by using different microscopy techniques

High glucose and increased oxidative stress levels are the known important mediators of diabetic nephropathy. However, the effects of these mediators on tissue damage basically due to extracellular matrix expansion in mesangial cells have yet to be fully examined within the context of early stage diabetic nephropathy. In this study, we attempted to characterize changes in mesangial cells of streptozotocin-induced diabetic rats with a comparative investigation of kidney tissue by using different microscopy techniques. The serum levels of urea and creatinine of diabetic rats, as biomarkers of kidney degeneration, decreased significantly compared to those of age-matched controls. In diabetic rats, there are increased malondialdehyde and oxidized-glutathione levels as well as reduced-glutathione and glutathione-peroxidase activity levels in renal tissue compared to those of the controls. By using light and electron microscopies, we showed that there were marked thickening in Bowman's membrane and glomerular capillary wall, increased amount of extracellular matrix often occupying Bowman's space, degenerations in tubules, an increased number of mesangial cells in the network of glomerular capillary walls, and increased amount of lipid accumulation in proximal tubules in the renal tissue of diabetic rats. Our confocal microscopy data confirmed also the presence of irregularity and widened in glomerular capillaries, their attachment to the Bowman's capsule, degenerated heterochromatin, thickening in foci of glomerular basement membrane, and marked increase in mesangial cells. These results suggest that a detailed structural investigation of kidney tissue provides further information on the important role of mesangial cells in pathogenesis of diabetic nephropathy.

Can improved glycemic control slow renal function decline at all stages of diabetic nephropathy?

Observational studies have shown the strong association between level of glycemic control and the key outcome measure, risk of glomerular filtration rate (GFR) loss rather than subsequent course of albumin excretion, in type 1 diabetes patients at all stages of nephropathy. However, it has not been clear if clinical interventions designed to normalize glycemic control are equally effective at all stages, such as primary prevention in normoalbuminuric patients, secondary prevention in microalbuminuria and macroalbuminuria, or tertiary prevention aimed at slowing or reversing further loss of GFR once impaired. Substantial randomized controlled trial data from the Diabetes Control and Complications Trial and Epidemiology of Diabetes Interventions and Complications exists to support postponement, but not outright prevention, of GFR loss in normoalbuminuric patients. Although secondary and tertiary prevention systematic studies are limited to methodologically insufficient insulin pump and transplantation trials, the reversal of advanced glomerular lesions observed in whole-pancreas transplant recipients who experienced long-term glycemic normalization offers convincing support for further research into glycemic interventions specifically for GFR preservation. In light of existing literature, we encourage the design of secondary and tertiary prevention trials that incorporate biomarker methods for identifying patients at highest risk of GFR loss because interventions to normalize hyperglycemia are resource-intensive and may be applied unnecessarily to clinical populations at low long-term GFR loss risk.

Diabetic nephropathy and extracellular matrix

Diabetic nephropathy (DN) is a serious complication in diabetes. Major typical morphological changes are the result of changes in the extracellular matrix (ECM). Thus, basement membranes are thickened and the glomerular mesangial matrix and the tubulointerstitial space are expanded, due to increased amounts of ECM. One important ECM component, the proteoglycans (PGs), shows a more complex pattern of changes in DN. PGs in basement membranes are decreased but increased in the mesangium and the tubulointerstitial space. The amounts and structures of heparan sulfate chains are changed, and such changes affect levels of growth factors regulating cell proliferation and ECM synthesis, with cell attachment affecting endothelial cells and podocytes. Enzymes modulating heparan sulfate structures, such as heparanase and sulfatases, are implicated in DN. Other enzyme classes also modulate ECM proteins and PGs, such as matrix metalloproteinases (MMPs) and serine proteases, such as plasminogen activator, as well as their corresponding inhibitors. The levels of these enzymes and inhibitors are changed in plasma and in the kidneys in DN. Several growth factors, signaling pathways, and hyperglycemia per se affect ECM synthesis and turnover in DN. Whether ECM components can be used as markers for early kidney changes is an important research topic, whereas at present, the clinical use remains to be established.

Inhibition of advanced glycation end product formation by Pu-erh tea ameliorates progression of experimental diabetic nephropathy

Accumulation of advanced glycation end products (AGEs) has been implicated in the development of diabetic nephropathy. We investigated the effects of Pu-erh tea on AGE accumulation associated with diabetic nephropathy. Although it did not affect blood glucose levels and insulin sensitivy, Pu-erh tea treatment for 8 weeks attenuated the increases in urinary albumin, serum creatinine, and mesangial matrix in db/db mice. We found that Pu-erh tea prevented diabetes-induced accumulation of AGEs and led to a decreased level of receptor for AGE expression in glomeruli. Both production and clearance of carbonyl compounds, the main precursor of AGE formation, were probably attenuated by Pu-erh tea in vivo independent of glyoxalase I expression. In vitro, HPLC assay demonstrated Pu-erh tea could trap methylglyoxal in a dose-dependent manner. Our study raises the possibility that inhibition of AGE formation by carbonyl trapping is a promising approach to prevent or arrest the progression of diabetic complications.

Proteases in Plasma and Kidney of db/db Mice as Markers of Diabetes-Induced Nephropathy

Db/db mice are overweight, dyslipidemic and develop diabetic complications, relevant for similar complications in human type 2 diabetes. We have used db/db and db/+ control mice to investigate alterations in proteinase expression and activity in circulation and kidneys by SDS-PAGE zymography, electron microscopy, immunohistochemistry, Western blotting, and in situ zymography. Plasma from db/db mice contained larger amounts of serine proteinases compared to db/+ mice. Kidneys from the db/db mice had a significantly larger glomerular surface area and somewhat thicker glomerular basement membranes compared to the db/+ mice. Furthermore, kidney extracts from db/+ mice contained metalloproteinases with M_r of approximately 92000, compatible with MMP-9, not observed in db/db mice. These results indicate that higher levels of serine proteinases in plasma may serve as potential markers for kidney changes in db/db mice, whereas a decrease in MMP-9 in the kidney may be related to the glomerular changes.

Pathologic classification of diabetic nephropathy

Although pathologic classifications exist for several renal diseases, including IgA nephropathy, focal segmental glomerulosclerosis, and lupus nephritis, a uniform classification for diabetic nephropathy is lacking. Our aim, commissioned by the Research Committee of the Renal Pathology Society, was to develop a consensus classification combining type1 and type 2 diabetic nephropathies. Such a classification should discriminate lesions by various degrees of severity that would be easy to use internationally in clinical practice. We divide diabetic nephropathy into four hierarchical glomerular lesions with a separate evaluation for degrees of interstitial and vascular involvement. Biopsies diagnosed as diabetic nephropathy are classified as follows: Class I, glomerular basement membrane thickening: isolated glomerular basement membrane thickening and only mild, nonspecific changes by light microscopy that do not meet the criteria of classes II through IV. Class II, mesangial expansion, mild (IIa) or severe (IIb): glomeruli classified as mild or severe mesangial expansion but without nodular sclerosis (Kimmelstiel-Wilson lesions) or global glomerulosclerosis in more than 50% of glomeruli. Class III, nodular sclerosis (Kimmelstiel-Wilson lesions): at least one glomerulus with nodular increase in mesangial matrix (Kimmelstiel-Wilson) without changes described in class IV. Class IV, advanced diabetic glomerulosclerosis: more than 50% global glomerulosclerosis with other clinical or pathologic evidence that sclerosis is attributable to diabetic nephropathy. A good interobserver reproducibility for the four classes of DN was shown (intraclass correlation coefficient = 0.84) in a test of this classification.

Continuous subcutaneous insulin infusion (CSII) versus multiple insulin injections for type 1 diabetes mellitus

BACKGROUND

Type 1 diabetes is a metabolic disorder resulting from a defect in insulin secretion. Onset of type 1 diabetes mellitus may occur at any age and it is one of the most common chronic diseases of childhood and adolescence. Since there are no interventions known to prevent onset, it is vital that effective treatment regimes are available. Glycaemic control is maintained by replacement of insulin and may be in the form of 'conventional' insulin therapy (multiple injections per day) or continuous subcutaneous insulin infusion (CSII).

OBJECTIVES

To assess the effects of CSII compared to multiple insulin injections (MI) in people with type 1 diabetes mellitus.

SEARCH STRATEGY

Studies were obtained from electronic searches of The Cochrane Library, MEDLINE, EMBASE and CINAHL.

SELECTION CRITERIA

Studies were included if they were randomised controlled trials comparing CSII with three or more insulin injections per day (MI) in people with type 1 diabetes mellitus.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed risk of bias and extracted characteristics of included studies. Authors contacted study investigators to obtain missing information. Generic inverse variance meta-analyses using a random-effects model were performed.

MAIN RESULTS

Twenty three studies randomised 976 participants with type 1 diabetes to either intervention. There was a statistically significant difference in glycosylated haemoglobin A1c (HbA1c) favouring CSII (weighted mean difference -0.3% (95% confidence interval -0.1 to -0.4). There were no obvious differences between the interventions for non-severe hypoglycaemia, but severe hypoglycaemia appeared to be reduced in those using CSII. Quality of life measures suggest that CSII is preferred over MI. No significant difference was found for weight. Adverse events were not well reported, no information is available on mortality, morbidity and costs.

AUTHORS' CONCLUSIONS

There is some evidence to suggest that CSII may be better than MI for glycaemic control in people with type 1 diabetes. Non-severe hypoglycaemic events do not appear to be reduced with CSII. There is insufficient evidence regarding adverse events, mortality, morbidity and costs.

The natural progression of kidney injury in young type 1 diabetic patients

Diabetes is the most common cause of end-stage renal disease in industrialized countries. This article describes the structural changes in early diabetic nephropathy and the relationship with renal functional parameters, blood pressure, and albumin excretion. The detrimental influence of sustained hyperglycemia and/or glycemic fluctuations on renal structural change has been well documented. Tight glycemic control is paramount to preventing the development, and even the regression, of renal lesions. As much of the renal injury from diabetes occurs in clinical silence before symptoms or laboratory findings of renal injury are evident, finding early markers of risk is imperative so that nephropathy can be prevented. Currently, the only clinical surrogate marker of diabetic renal injury available is microalbuminuria. However, given the reports of regression of microalbuminuria back to normoalbuminuria, the reliability of this tool as an indicator of risk has been questioned. The need for alternative, noninvasive surrogate markers is described in this report.

Matrix metalloproteinases in subjects with type 1 diabetes

Background

Nephropathy is serious complication of diabetes. We have previously shown that level of the proteoglycan syndecan-1 in blood is associated with ultrastructural kidney changes in young persons with type 1 diabetes. Dysregulation of matrix metalloproteinases (MMPs) and tissue inhibitors of matrix metalloproteinases (TIMPs) may contribute to the development of nephropathy. The aim of this study was to investigate if the levels of MMPs in blood samples are potential markers of early nephropathy in type 1 diabetes.

Methods

Blood samples were collected from type 1 diabetes patients after 11 years of diabetes (n = 15) and healthy volunteers (n = 12) and stored at ÷80°C until measurement. Levels and activities of serum MMP-2, MMP-9, TIMP-1 and TIMP- 2 were analyzed and compared to those of control individuals using ELISA, SDS-PAGE gelatin zymography, and Western blot analysis.

Results

The serum levels of both MMP-9 and MMP-2 were significantly higher in subjects with type 1 diabetes, compared to controls (p = 0.016 and p = 0.008 respectively). Western blotting revealed no differences between the two groups in the levels of TIMP-1 or TIMP-2, respectively.

Conclusion

Our MMP analysis of serum from a limited number of patients with type 1 diabetes suggest that such analysis is potentially useful as markers in studies of people at risk of progression to chronic kidney disease.

Early histological changes in the kidney of people with morbid obesity

BACKGROUND

Morbid obesity represents a major health problem with increasing incidence worldwide. The clinical manifestation of renal involvement in obesity is proteinuria, and the histological feature is glomerulomegaly with or without focal and segmental glomerulosclerosis (FSGS). In this study, we have investigated the very early histological changes in kidneys of people with morbid obesity and no proteinuria. Patients and methods. Eighteen patients with body mass index (BMI) >50 kg/m(2) who underwent a variant of biliopancreatic diversion with Roux-en-Y reconstruction (BPD-RYGBP) and consented to undergo a renal biopsy during the surgical procedure were included in the study. The estimation of early histological changes was performed on light (n = 18) and electron microscopy (n = 13).

RESULTS

The mean glomerular cross-sectional area was 30 943 +/- 10,984 microm(2) that is higher than that observed in non-obese individuals. In 21% of the examined glomeruli, the glomerular planar surface area (GPSA) was >40,000 microm(2). Thickening of the glomerular basement membrane (GBM) and scattered paramesangial deposits were identified in 9 of 13 patients (70%) whose renal tissue was examined by electron microscopy. A reduction in the slit pore frequency was observed in obese patients due to extensive foot process effacement. Significant positive correlations between mean GPSA and body weight (r = 0.462, P = 0.05), and between GBM thickness and HbA1c, serum total cholesterol and triglyceride levels (r = 0.60, P = 0.05; r = 0.789, P = 0.004; r = 0.70, P = 0.016, respectively), were observed.

CONCLUSIONS

Glomerulomegaly as well as histological lesions resembling those of early diabetic nephropathy are observed in kidney biopsies of patients with morbid obesity even before the appearance of microalbuminuria. The potential regression of these changes after weight loss needs to be clarified.

Renal tubulointerstitial expansion is associated with endothelial dysfunction and inflammation in type 1 diabetes

OBJECTIVE

Diabetic nephropathy has been considered to be primarily of glomerular origin, but there is now compelling evidence that disruption of the tubulointerstitial architecture determines the outcome of diabetic nephropathy in interplay with the glomerular damage. We investigated whether reactive oxidative species, pro-inflammatory cytokines and endothelial dysfunction were implicated in the progression of tubulointerstitial damage in young subjects with type 1 diabetes.

MATERIAL AND METHODS

In a prospective study, we investigated 18 young subjects (mean age 21 years) with type 1 diabetes and microalbuminuria. Quantitative morphometry concerning glomerular and tubulointerstitial changes was performed at baseline (i.e. mean duration of diabetes 10 years) and 2.5 and 8 years later. Markers of endothelial activation and inflammation, intercellular adhesion molecule-1, vascular cell adhesion molecule-1, tumour necrosis factor-alpha, interleukin-6, interleukin-8 and highly sensitive C-reactive protein were measured at baseline and after 8 years. Tissue plasminogen activator antigen and plasminogen activator inhibitor (PAI-1 activity) and asymmetric dimethylargine (ADMA) were measured at baseline and after 2.5 years.

RESULTS

PAI-1 activity at baseline was a significant independent variable of the 8-year increment in interstitial volume fraction (Vv(Int/cortex)). ADMA/L-arginine ratio at baseline was associated with the increment in Vv(Int/cortex) during 2.5 years (p<0.01), still significant after adjustment for covariates (p = 0.02). No associations between Vv(Int/cortex) and glomerular parameters, HaemoglobinA1c and urinary albumin excretion were observed.

CONCLUSIONS

Biomarkers involved in interstitial volume expansion seem to be different from those of mesangial expansion in early diabetic nephropathy. PAI-1 activity may have a predictive role in the development of the tubulointerstitial expansion.

Renal structure as an indicator for development of albuminuria in normo- and microalbuminuric type 2 diabetic patients

Baseline glomerular structure in microalbuminuric (MA) and proteinuric Caucasian type 2 diabetic patients predicted progressive glomerular filtration rate decline while baseline urinary albumin excretion (UAE) did not. Little is known about whether or not renal structure at the early stages of diabetic nephropathy (DN) in type 2 diabetic patients can predict further functional development of DN. Baseline renal structure and function and follow-up data of renal function were examined in 17 type 2 diabetic patients (11 men, 45+/-7 (mean+/-S.D.) years old) with known diabetes duration 11+/-8 years without definable renal disease other than DN. Six patients showed normoalbuminuria (NA), 11 microalbuminuria (MA), and were followed up for 6.4+/-1.8 years after the baseline renal biopsy. Light and electron microscopic morphometric analyses provided quantitative glomerular and tubulointerstitial structural changes. No statistically significant difference was observed in hemoglobin A1c (HbA1c) values or mean blood pressure (MBP) between baseline and follow-up, even though the number of patients placed on antihypertensive drugs increased from 3 to 7. Follow-up UAE was not significantly different from the baseline UAE although 13 of 17 cases showed an increase. Baseline UAE did not correlate with the follow-up UAE or morphometric measures. Glomerular basement membrane width and volume fraction of the mesangium and mesangial matrix positively correlated with follow-up UAE. In NA and MA Japanese type 2 diabetic patients, baseline renal structural measures are more reliable indicators for the development of UAE than baseline UAE.

Continuous subcutaneous insulin infusion versus multiple daily insulin injections in patients with diabetes mellitus: systematic review and meta-analysis

AIMS

We compared the effects of continuous subcutaneous insulin infusion (CSII) with those of multiple daily insulin (MDI) injections on glycaemic control, risk of hypoglycaemic episodes, insulin requirements and adverse events in type 1 and type 2 diabetes mellitus.

METHODS

The electronic databases MEDLINE, EMBASE and CENTRAL were systematically searched for randomised controlled trials up to March 2007. A systematic review and meta-analysis were performed.

RESULTS

Overall, 22 studies were included (17 on type 1 diabetes mellitus, two on type 2 diabetes mellitus, three on children). With regard to adults with type 1 diabetes mellitus, our meta-analysis found a between-treatment difference of -0.4% HbA(1c) (six studies) in favour of CSII therapy. Available median rates of mild or overall hypoglycaemic events were comparable between the different interventions (1.9 [0.9-3.1] [CSII] vs 1.7 [1.1-3.3] [MDI] events per patient per week). Total daily insulin requirements were lower with CSII than with MDI therapy. In patients with type 2 diabetes mellitus, CSII and MDI treatment showed no statistically significant difference for HbA(1c). The incidence of mild hypoglycaemic events was comparable between the treatment groups. In adolescents with type 1 diabetes mellitus, glycated haemoglobin and insulin requirements were significantly lower in the CSII groups; no data were available on hypoglycaemic events. The only study performed in younger children did not provide enough data for conclusive inferences. No overall conclusions were possible for severe hypoglycaemia and adverse events for any of the different patient groups due to rareness of such events, different definitions and insufficient reporting.

CONCLUSIONS/INTERPRETATION

CSII therapy in adults and adolescents with type 1 diabetes mellitus resulted in a greater reduction of glycated haemoglobin, in adult patients without a higher rate of hypoglycaemia. No beneficial effect of CSII therapy could be detected for patients with type 2 diabetes mellitus.

Long-term prevention of diabetic nephropathy: an audit

AIMS/HYPOTHESIS

In type 1 diabetic patients with microalbuminuria not receiving antihypertensive treatment, an increase in urinary AER (UAER) of 6-14%/year and a risk of developing diabetic nephropathy (DN) of 3-30%/year have been reported. We audited the long-term effect of blocking the renin-angiotensin-aldosterone system (RAAS) with an ACE inhibitor (ACEI) or angiotensin II receptor blocker (ARB) in microalbuminuric type 1 diabetic patients on progression of microalbuminuria and development of DN.

METHODS

All patients with type 1 diabetes and persistent microalbuminuria (30-300 mg/24 h) were identified (n=227) in 1995 at Steno Diabetes Center and followed for 11 years. Development of DN was defined as a UAER of >300 mg/24 h in two of three consecutive urine samples.

RESULTS

Age and duration of diabetes at baseline (mean+/-SD) were 46+/-15 and 28+/-13 years, respectively. During follow-up 14 patients emigrated and 58 (26%) died. Over the same period 79% were treated with an ACEI or ARB. There was a mean decline in UAER of 4%/year. Sixty-five patients (29%) progressed to overt DN, corresponding to 3.1%/year. However, 29 of them regressed to normo- or microalbuminuria on intensified antihypertensive treatment. Glycaemic control and blood pressure remained nearly unchanged.

CONCLUSIONS/INTERPRETATION

In our outpatient clinic, the implementation of RAAS-blocking treatment in type 1 diabetic patients with microalbuminuria successfully reduced long-term progression to overt DN to a rate similar to those previously reported in randomised, double-blind intervention trials of shorter duration using RAAS blockade.

Diabetic nephropathy in children and adolescents

Type 1 diabetes mellitus (T1DM) commonly occurs in childhood or adolescence, although the rising prevalence of type 2 diabetes mellitus (T2DM) in these age groups is now being seen worldwide. Diabetic nephropathy (DN) develops in 15-20% of subjects with T1DM and in similar or higher percentage of T2DM patients, causing increased morbidity and premature mortality. Although overt DN or kidney failure caused by either type of diabetes are very uncommon during childhood or adolescence, diabetic kidney disease in susceptible patients almost certainly begins soon after disease onset and may accelerate during adolescence, leading to microalbuminuria or incipient DN. Therefore, all diabetics warrant ongoing assessment of kidney function and screening for the earliest manifestations of renal injury. Pediatric health care professionals ought to understand about risk factors, strategy for prevention, method for screening, and treatment of early DN. This review considers each form of diabetes separately, including natural history, risk factors for development, screening for early manifestations, and strategy recommended for prevention and treatment of DN in children and adolescents.

Involvement of advanced glycation end products in the pathogenesis of diabetic complications: the protective role of regular physical activity

Advanced glycation end products (AGEs) may play an important role in the pathogenesis of chronic diabetic complications and in the natural process of biological aging. In fact, maintained hyperglycaemia favours the formation of AGEs at the tissue level in diabetic patients, which may influence the triggering of different chronic pathologies of diabetes such as retinopathy, nephropathy, neuropathy and macro- and micro-vascular diseases. Moreover, the literature has also demonstrated the involvement of AGEs in biological aging, which may explain the accelerated process of aging in diabetic patients. The practice of regular physical activity appears to positively influence glycaemic control, particularly in type 2 diabetes mellitus patients. This occurs through the diminution of fasting glycaemia, with a consequent reduction of glycation of plasmatic components suggested by the normalisation of HbA1c plasmatic levels. This exercise-induced positive effect is evident in the blood of diabetic patients and may also reach the endothelium and connective tissues of different organs, such as the kidneys and eyes, and systems, such as the cardiovascular and nervous systems, with a local reduction of AGEs production and further deceleration of organ dysfunction. The aim of this paper was to review the literature concerning this topic to coherently describe the harmful effects of AGEs in organ dysfunction induced by diabetes in advanced age as well as the mechanisms behind the apparent protection given by the practice of regular physical activity.

Hyperglycemia and diabetic renal change in a model of polyvinyl alcohol bioartificial pancreas transplantation

OBJECTIVES

We have developed a bioartificial pancreas transplantation method using polyvinyl alcohol. Using this model, the relationship between hyperglycemia and parameters that represent renal function was investigated.

METHODS

Plasma glucose, 1,5-anhydro-d-glucitol (1,5-AG), and renal factors including plasma urea nitrogen and creatinine levels, urine volume, glucose, and albumin were examined once a week for 9 weeks in diabetic mice with or without transplantation of encapsulated rat islets, and in normal C57BL/6 mice. The mesangial matrix fraction of the glomerulus was measured histologically. The mice were classified into 3 groups according to their mean plasma glucose levels as either severe (n = 17) or mild (n = 23) hyperglycemia or normoglycemia (n = 11). The plasma glucose, renal factors, and mesangial matrix fraction were tested by single and multiple regression analyses.

RESULTS

Almost all the renal factors correlated significantly with mean plasma glucose and 1,5-AG levels. The level and duration of hyperglycemia estimated by the area under the curve above basal correlated most significantly with mesangial matrix fraction.

CONCLUSIONS

Bioartificial pancreas transplantation significantly reduced the deterioration of renal factors. The 1,5-AG was useful to predict urine albumin loss. The level and duration of hyperglycemia determined the degree of renal damage, which were reduced by bioartificial pancreas transplantation.

Glucose modulates basement membrane fibroblast growth factor-2 via alterations in endothelial cell permeability

The effects of glucose extremes on vascular physiology and endothelial cell function have been examined across a range of time scales. Not unexpectedly, chronic glucose exposure induces long term tissue effects. Yet short term exposure can also impose lasting consequences. The persistence of vascular pathology after euglycemic restoration further suggests a glucose exposure memory. Slow turnover reservoirs such as basement membrane are candidates for prolongation of acute events. We hypothesized that glucose-induced vascular dysfunction is related to altered vasoactive compound handling within the endothelial cell-basement membrane co-regulatory unit. Endothelial cell basement membrane-associated fibroblast growth factor-2 increased linearly with culture glucose within days of elevated glucose exposure. Surprisingly, basement membrane fibroblast growth factor-2 binding kinetics remained unchanged. The glucose-induced increase in basement membrane fibroblast growth factor-2 was instead related to enhanced endothelial cell fibroblast growth factor-2 release and permeability. Cellular fibroblast growth factor-2 release occurred concomitant with apoptosis but was not blocked by caspase inhibitors. These data suggest that release was associated with sub-lethal early apoptotic cell membrane damage, perhaps related to reactive oxygen species formation. High glucose basement membrane in turn enhanced endothelial cell proliferation in a fibroblast growth factor-2-dependent manner. We now show that glucose-induced alterations in endothelial cell function promote changes in basement membrane composition, and these changes further affect endothelial cell function. These data highlight the interrelationship of cell and basement membrane in pathological conditions such as hyperglycemia. These phenomena may explain long term effects on the endothelium of short term exposure to glucose extremes.

Renal protection in diabetes: role of glycemic control

Diabetes is the most common cause of ESRD in Western countries. This article describes the impact of glycemic control in the various stages of the disease and considers the impact of tight glycemic control on the development and progression of diabetic nephropathy (DN). The Diabetes Control and Complications Trial and the United Kingdom Prospective Diabetic Study have demonstrated in type 1 and type 2 diabetes that intensive glycemic control significantly reduces the risk for development of microalbuminuria. Although observational studies suggest an impact of glycemia also on the progression of DN, fewer data are available on the impact of improved metabolic control in secondary prevention. The long-term follow-up of the patients who participated in the Diabetes Control and Complications Trial (Epidemiology of Diabetes Interventions and Complications Study) demonstrated a sustained effect of previous tight glycemic control on both development and progression of DN. Finally, long-term normoglycemia, achieved by pancreas transplantation, is able not only to prevent the development of early diabetic glomerulopathy in kidney transplant recipients but also to halt progression and induce regression of the established diabetic renal lesions in nonuremic patients. Taken together, these studies strongly demonstrate that improvement in glucose control is the most important therapeutic approach in primary prevention. Tight glycemic control also is important in slowing progression of DN, and if blood glucose is normalized, then regression of DN can be achieved. Therefore, a target of glycated hemoglobin levels <7% should be recommended in all patients with diabetes.

The course of diabetic glomerulopathy in patients with type I diabetes: a 6-year follow-up with serial biopsies

Diabetic nephropathy is a severe complication and few studies have described the early morphological changes over time. Two kidney biopsies were performed, within a 6-year interval, in 29 primarily normoalbuminuric patients, aged 24 years at the second biopsy. These were examined with light and electron microscopy. Glomerular filtration rate, and effective renal plasma flow were determined with inulin and para-aminohippurate clearances. Urinary albumin excretion rate and the 24 ambulatory blood pressure were determined. Ten patients had developed microalbuminuria and/or hypertension; of these, six were treated with antihypertensive medication for 2 years or more. Significant increases were found in night time diastolic blood pressure and decreases in systolic and diastolic dipping. The glomerular volume, mesangial volume, mesangial matrix volume fraction and foot process width increased significantly. The group that was treated later for complications had the worst long-term metabolic control, thicker basement membranes and larger mesangial matrix and volume at the first biopsy, than the persistent normoalbuminuric group. During the follow-up, the untreated group with complications and the persistent normoalbuminuric group showed an increase in morphological parameters, whereas no progression occurred in the treated patients who also improved their metabolic control. In conclusion, the morphological parameters deteriorated in the normoalbuminuric patients and in those with complications, but were unchanged in the small antihypertensive-treated group with improved metabolic control.

Slowing the Progression of Adult Chronic Kidney Disease

When kidney disease of any aetiology results in substantial loss of nephrons, a common clinical syndrome, characterised by hypertension, proteinuria and a progressive decline in renal function, ensues. This observation suggests that common mechanisms may contribute to progressive renal injury and that therapeutic interventions that inhibit these common pathways may afford renal protection. Research to date has identified several mechanisms that may contribute to progressive renal injury including glomerular haemodynamic changes, multiple effects of angiotensin II and detrimental effects of excessive filtration of plasma proteins by injured glomeruli. Clinical trials over the past decade have identified several interventions that are effective in slowing the rate of progression of chronic kidney disease (CKD). The use of ACE inhibitors, angiotensin receptor antagonists or a combination of the two should be regarded as fundamental to any therapy for slowing the rate of CKD progression. Hypertension should be treated aggressively to achieve a blood pressure target of < 130/80 mm Hg. Reduction of proteinuria to < 0.5 g/day should be regarded as an independent therapeutic goal. Although inconclusive, there is some evidence to support moderate dietary protein restriction to 0.6 g/kg/day in appropriate patients. Hyperlipidaemia may contribute to CKD progression and should be treated to reduce cardiovascular risk and potentially improve renal protection. Smoking cessation should be encouraged and, where necessary, assisted. Among diabetic patients tight glycaemic control should be achieved (glycosylated haemoglobin < 7%). These interventions are simple and relatively inexpensive. If applied to all patients with CKD they will result in substantial slowing of renal function decline in many patients and thereby reduce the number who progress to end-stage renal disease and require renal replacement therapy.

Protective effects of chronic melatonin treatment against renal injury in streptozotocin-induced diabetic rats

The aim of this study was to investigate the effects of melatonin as an antioxidant, on prevention and treatment of streptozotocin (STZ)-induced diabetic renal injury in rats. Male Wistar rats were divided into four groups: (1) untreated, (2) melatonin-treated, (3) untreated diabetic (UD), (4) melatonin-treated diabetic (MD). Experimental diabetes was induced by single dose (60 mg/kg, i.p.) STZ injection. For 3 days prior to administration of STZ, melatonin was injected (200 microg/kg/day, i.p.); these injections were continued until the end of the study (4 weeks). Malondialdehyde (MDA) levels as a marker of lipid peroxidation were significantly increased in the renal homogenates of UD animals and decreased after melatonin administration. The activity of the antioxidative enzyme glutathione peroxidase (GSH-Px) was significantly reduced in UD rats. Melatonin treatment reversed STZ-induced reduction of GSH-Px activity without having an effect on blood glucose. Upon histopathological examination, it was observed that the melatonin treatment prevented the renal morphological damage caused by diabetes. Upon immunohistochemical investigation, glomerular anti-laminin beta1 staining decreased in MD rats. Additionally, no tubular anti-IGF-1 staining was observed in melatonin-treated rats. In conclusion, chronically administered melatonin reduced renal injury in STZ-induced diabetic rats and thus it may provide a useful therapeutic option in humans to reduce oxidative stress and the associated renal injury in patients with diabetes mellitus.

Treatment of diabetic nephropathy in its early stages

Diabetic nephropathy is one of the most frequent causes of end-stage renal disease (ESRD), and, in recent years, the number of diabetic patients entering renal replacement therapy has dramatically increased. The magnitude of the problem has led to numerous efforts to identify preventive and therapeutic strategies. In normoalbuminuric patients, optimal glycemic control (HbA(1c) lower than 7.5%) plays a fundamental role in the primary prevention of ESRD [weighted mean relative risk reduction (RRR) approximately 37% for metabolic control versus trivial renoprotection for intensive anti-hypertensive therapy or ACE-inhibitors (ACE-I)]. In the microalbuminuric stage, strict glycemic control probably reduces the incidence of overt nephropathy (weighted mean RRR approximately 50%), while blood pressure levels below 130/80 mmHg are recommended according to the average blood pressure levels obtained in various studies. In normotensive patients, ACE-I markedly reduce the development of overt nephropathy almost regardless of blood pressure levels; in hypertensive patients, ACE-I are less clearly active (weighted mean RRR approximately 23% versus other drugs), whereas angiotensin-receptor blockers (ARB) appear strikingly renoprotective. Once overt proteinuria appears, it is uncertain whether glycemic control affects the progression of nephropathy. In type 1 diabetes, various anti-hypertensive treatments, mainly ACE-I, are effective in slowing down the progression of nephropathy; in type 2 diabetes, two recent studies demonstrate that ARB are superior to conventional therapy or calcium channel blockers (CCB). In clinical practice, pharmacological tools are not always used to the best benefit of the patients. Therefore, clinicians and patients need to be educated regarding the renoprotection of drugs inhibiting the renin-angiotensin system (RAS) and the overwhelming importance of achieving target blood pressure.

Comorbidity and cardiovascular risk factors in patients with chronic kidney disease

The mortality rate among dialysis patients is high. Although guidelines have been in place to improve outcomes in dialysis patients, new emphasis is being placed on better management of patients who are pre-end-stage renal disease (pre-ESRD)-patients with chronic kidney disease (CKD). Spearheaded by the National Kidney Foundation, the National Institute of Health, and the nephrology community at large, an effort is underway to improve the care of patients with kidney disease. We hope that improvement in health and outcomes of patients with kidney disease will be optimized through attention to care before the development of advanced renal disease. Cardiovascular disease (CVD) is an important comorbidity of chronic kidney disease, and reducing cardiovascular events in this population is an important goal for the people who care for chronic kidney disease patients. In this article, we review the available literature regarding certain risk factors for cardiovascular disease: proteinuria, hyperglycemia, hypertension, homocysteine, hyperlipidemia, and inflammation. When possible, recommendations for treatment are provided based on the information reviewed.

Differential expression of type IV collagen isoforms in rat glomerular endothelial and mesangial cells

Type IV collagen, which is encoded by six genetically distinct alpha-chains (alpha 1-alpha 6), is a major component of the kidney glomerulus. The alpha 1(IV) and alpha 2(IV) chains are present predominantly in the mesangial matrix, whereas the alpha 3(IV), alpha 4(IV), and alpha 5(IV) chains are localized almost exclusively to the glomerular basement membrane (GBM). Thickening of the GBM and expansion of the mesangial matrix are believed to contribute to the pathogenesis of diabetic nephropathy. In the present study, we evaluated the expression of alpha 1(IV), alpha 3(IV), and alpha 5(IV) chains in rat glomerular endothelial (GEndC) and mesangial cells (GMC). Under physiological concentrations of glucose (5 mM), alpha 1(IV) and alpha 5(IV) chains were detectable in GMCs, with an obvious absence of alpha 3(IV) chain. All three isoforms tested were present in GEndCs. At diabetic concentrations of glucose (25 mM), alpha 1(IV) was up-regulated in GMCs, whereas expression level of alpha 1(IV) remained unaltered in GEndCs. The alpha 3(IV) and alpha 5(IV) chains were up-regulated in GEndCs, but remained unchanged in GMCs under diabetic glucose concentrations (25 mM). Collectively, our results demonstrate that GMC might contribute to mesangial matrix expansion, mediated by alpha 1(IV) collagen, while GEndC might contribute to thickening of GBM, mediated by alpha 3(IV) collagen, in patients with diabetic nephropathy.

Treatment of hypertension and microalbuminuria in children and adolescents with type 1 diabetes mellitus

Nephropathy is the main cause of morbidity and mortality in patients with type 1 diabetes and, in adults, persistent microalbuminuria is the best marker of the consequent risk for its development. In the pediatric population, puberty represents the most important risk factor for the development of microangiopathic complications, although it is not necessarily associated with the progression to frank proteinuria. As many as 50% of subjects may revert to normoalbuminuria. Hypertension is a further risk factor and may accelerate the progression of micro- and macrovascular complications. There is evidence that angiotensin-converting enzyme (ACE) inhibitors reduce renal damage by one or more mechanisms independent of their antihypertensive effects--hence they represent the drug of choice for the treatment of diabetic nephropathy. However, as angiotensin II receptor antagonists are more specific, they may become the obvious treatment choice in the near future. There is no consensus as to who should be treated and when treatment with renoprotective drugs should begin in the pediatric population, due to the lack of a clear definition of the natural history of microalbuminuria in this age group. In this review some models and controversial aspects of this issue are presented and discussed.

The early natural history of nephropathy in type 1 diabetes: I. Study design and baseline characteristics of the study participants

This report describes the design and baseline demographic and clinical data in the study of the early natural history of diabetic nephropathy (DN) in type 1 diabetes carried out by the International Diabetic Nephropathy Study Group. The study enrolled 243 patients ages 10-40 years (16.8 +/- 6.0, mean +/- SD) with type 1 diabetes for 2-20 years (8.0 +/- 4.2) at centers in the United States (Minneapolis), Canada (Montreal), and France (Paris). At baseline, all patients were normotensive, none had reduced glomerular filtration rate (GFR), and all but eight were normoalbuminuric (NA). All patients had baseline renal biopsies. During the study, patients will have multiple measurements of blood pressure (BP), renal function, albumin excretion rate (AER), glycemia, and other variables, with repeat renal biopsies planned at 5 years after baseline. The 31.3% of the approached patients who agreed to participate were similar in age, diabetes duration, HbA(1c), AER, and sex to those refusing participation. Age, diabetes duration, HbA(1c), and AER were similar among the three centers, but systolic BP, GFR, renal plasma flow (RPF), and filtration fraction were lower in the Paris center. The 153 patients with hyperfiltration (GFR >130 ml x min(-1) x 1.73 m(-2)) had greater RPF than those with normal GFR. The eight microalbuminuric patients tended to have longer duration of diabetes but were otherwise similar to the NA patients. The role of these and other variables in determining the development rate of the early lesions of DN over the 5 years between biopsies is the central issue under study.

Microvascular complications. Retinopathy and nephropathy

Diabetic retinopathy and diabetic nephropathy extract an enormous toll on patients with diabetes and an enormous burden on the health care system. With aggressive control of glycemia and blood pressure, coupled with aggressive use of laser photocoagulation and treatment of microalbuminuria, these problems can largely be eliminated. In the future, specific interventions may emerge that will allow interdiction of the pathophysiologic processes that lead to initiation and progression of these microvascular complications. The challenge for the primary care physician and diabetologist is to attain excellent glycemic control and aggressive control of blood pressure, while assuring that every patient has appropriate dilated fundus examinations at least annually, preferably by an ophthalmologist or retinal specialist, and regular screening for microalbuminuria. With such medical management, appropriate intervention can occur to reduce the risk of blindness and renal failure and to lessen the burden from diabetic retinopathy and nephropathy.

N-phenacylthiazolium bromide decreases renal and increases urinary advanced glycation end products excretion without ameliorating diabetic nephropathy in C57BL/6 mice

AIMS

Advanced glycation end products (AGE), which form from the non-enzymatic reaction of proteins and sugars, have been implicated in the pathogenesis of diabetic nephropathy. Recently, a compound [N-phenacylthiazolium bromide (PTB)] has been described which cleaves alpha,beta-dicarbonyl compounds. In the present study we used diabetic C57BL/6 mice to determine if PTB altered renal AGE levels and reduced diabetic glomerulosclerosis.

METHODS

Mice with stable hyperglycaemia induced by streptozotocin were given daily subcutaneous injections of either PTB (10 microg/g) or saline for 12 weeks. Renal-collagen bound AGE and urinary AGE-peptides were measured by ELISA using an anti-AGE-RNase antibody. Renal collagen-released Nepsilon(carboxymethyl)lysine (CML) and pentosidine were determined by high pressure liquid chromatography (HPLC). Glomerular lesions (volume and mesangial/total surface area) were evaluated by computer-assisted image analysis. We determined urinary protein/creatinine ratio as a functional parameter. AGE localization was examined by immunohistochemistry using the anti-AGE-RNase antibody.

RESULTS

Renal collagen-bound AGE were decreased and urinary AGE excretion was increased in PTB-treated diabetic mice. However, collagen-released CML and pentosidine were similar in both groups. Glomerular histology and morphometric analysis revealed also no differences between PTB-and saline-treated diabetic mice. The urinary protein/creatinine ratio was unaffected by PTB-treatment. AGE staining by anti-AGE-RNase antibody was present in Bowman's capsules, glomerular basement membranes and cortical tubules. It was decreased in all structures in PTB-treated diabetic mice.

CONCLUSION

In summary, PTB decreased renal AGE accumulation but did not ameliorate glomerular lesions or proteinuria. Thus, cleavage of AGE by PTB is not sufficient to prevent development of diabetic nephropathy in C57BL/6 mice.

Glycohemoglobin: A Primary Predictor of the Development or Reversal of Complications of Diabetes Mellitus

Background: Diabetes mellitus is a major health problem worldwide with long-term micro- and macrovascular complications responsible for a majority of its morbidity and mortality. The development and progression of these complications relate strongly to glycemic control.

Methods: We reviewed the literature extensively for studies that relate glycemic control to the development and progression of diabetic complications. We discuss the problems of standardizing glycohemoglobin measurements for monitoring diabetic therapy and also consider recently developed electrospray ionization mass spectrometry methods that have been considered as candidate reference methods for estimation of glycohemoglobin.

Results: Several clinical trials and studies have clearly shown that improved glycemic control is strongly associated with decreased development and/or progression of complications in both type 1 and type 2 diabetes mellitus. Irrespective of the methods used for estimating glycohemoglobin, these results underline the importance of glycohemoglobin for guiding therapy of diabetes mellitus. Recently developed candidate reference methods promise to yield greatly improved standardization for the measurement of glycohemoglobin.

Conclusions: Glycohemoglobin measurement remains the optimal indicator of glycemic control in diabetic patients, but translation of findings from clinical trials to clinical practice worldwide demands consistent values across all assays. To ensure that the important prognostic information still applies to all diabetic patients with the application of the reference method(s), the hemoglobin A1c values reported in the major clinical trials will have to be translated into statistically and computationally compatible values based on the new reference system(s).

Evolving strategies for renoprotection: diabetic nephropathy

A cumulative incidence of diabetic nephropathy of 25-40% has been documented after duration of diabetes of at least 25 years in both type 1 and type 2 diabetic patients. Diabetic nephropathy has become the leading cause (25-44%) of end-stage renal failure in Europe, the United States and Japan. Until the early 1980s, no renoprotective treatment was available for use in diabetic nephropathy. Death occurred on average 5-7 years after the onset of persistent proteinuria. It should be recalled that development of treatment modalities occurred in reverse order: in the early 1980s, antihypertensive treatment of diabetic nephropathy was introduced, and in the early 1990s, primary and secondary prevention with improved glycaemic control and angiotensin-converting enzyme inhibition. The two main treatment strategies for primary prevention of diabetic nephropathy are improved glycaemic control and blood pressure lowering, particularly using drugs such as angiotensin-converting enzyme inhibitors. Megatrials and meta-analyses have clearly demonstrated the beneficial effect of both the above-mentioned treatment modalities. Secondary prevention, that is, treatment modalities applied to diabetic patients with high risk of development of diabetic nephropathy (e.g. those with microalbuminuria) has been documented, applying angiotensin-converting enzyme inhibitors in both type 1 and type 2 diabetic patients. Furthermore, improved metabolic control reduces the risk of progression. In special cases (such as pancreas transplantation) even reversal of diabetic glomerular lesions has been documented. Antihypertensive treatment of patients with overt nephropathy induces a reduction in albuminuria, a reduction in the rate of decline of glomerular filtration rate, delays development of end-stage renal failure and improves survival. Many potential treatment modalities in preventing and treating diabetic nephropathy are presently being evaluated.

Effect of 3 years of antihypertensive therapy on renal structure in type 1 diabetic patients with albuminuria: the European Study for the Prevention of Renal Disease in Type 1 Diabetes (ESPRIT)

In the treatment of diabetic nephropathy, ACE inhibitor therapy reduces albumin excretion and slows the rate of decline in glomerular filtration rate (GFR). Our study was designed to investigate whether these effects lay in amelioration of the underlying glomerular structural abnormalities. A total of 54 type 1 diabetic patients with albuminuria and blood pressure (BP) <150/90 mmHg were randomized to receive 10 mg enalapril once daily, 10 mg nifedipine retard twice daily, or placebo in a multicenter double-blind study of 3 years' duration. Renal biopsy was performed at baseline and follow-up, and tissue was analyzed by standard morphometric methods. BP, GFR, albumin excretion rate (AER), and HbA1c were measured every 6 months. Enalapril lowered AER after 6 months by 26% (P < 0.05); however, this reduction was not sustained at 3 years. There was no significant effect of nifedipine or placebo on AER. GFR decreased by a similar average rate of 4.1 ml x min(-1) x year(-1) (95% CI 2.6-5.6) in all three groups. BP and HbA1c were unchanged throughout the study in all groups. At baseline, nearly all biopsies showed classic appearances of diabetic glomerulopathy. There was no detectable effect of enalapril compared with either nifedipine or placebo on renal structure over 3 years. However, we found that patients with increased AER have established glomerulopathy and a progressive average decline in GFR of 4.1 ml x min(-1) x year(-1) in the absence of overt hypertension, and baseline AER appeared predictive of subsequent mesangial volume fraction (r = 0.20, P = 0.0018). In this small cohort of nonhypertensive patients studied for 3 years, disease evolution appears unaffected by treatment with either enalapril or nifedipine.