Effects of candesartan, an angiotensin II type 1 receptor blocker, on diabetic nephropathy in KK/Ta mice

BACKGROUND: Although therapeutic effects of angiotensin II type 1 receptor blocker (ARB) on renal injury in non-insulin dependant diabetes mellitus (NIDDM) have been demonstrated, the beneficial effects and their mechanisms in diabetic nephropathy have not been well evaluated. METHODS: KK/Ta mice were divided into three groups according to the treatment: candesartan 4 mg/kg/day from 6 to 28 weeks of age (group I; early treatment); from 12 to 28 weeks of age (group II; late treatment); only vehicle (group III). BALB/c mice treated with vehicle were used as controls (group IV). Body weight (BW), systolic blood pressure (SBP), blood glucose, urinary type IV collagen and albumin excretion were measured every 4 weeks. Morphometry and immunohistology of albumin, transforming growth factor-beta1 (TGF-beta1) and Smad7 were performed in all groups. RESULTS: BW and blood glucose were higher in groups I, II and III than in group IV from 8 weeks. SBP was markedly reduced in groups I and II compared with group III (p < 0.05, p < 0.005). Urinary type IV collagen and albumin excretion were increased in group III compared to group IV (p < 0.05, p < 0.005), whereas they were reduced in groups I and II when compared to group III (p < 0.05). Morphometric analysis revealed that the whole glomerular area (WGA), glomerular tuft area (GTA), extracellular matrix area (ECMA) and intraglomerular cell nuclei number (NIGCN) were significantly reduced in groups I, II and IV compared to group III at 28 weeks. In immunohistochemistry, TGF-beta1 expression in both glomeruli and tubules of groups I and II decreased compared to that of group III at 28 weeks, while Smad7 in group III glomeruli was reduced compared to that in groups I and II. CONCLUSIONS: It appears that candesartan reduced urinary type IV collagen and albumin excretion, and attenuated glomerular hypertrophy and mesangial matrix accumulation by the TGF-betaS/Smad signaling pathway in KK/Ta mice with diabetic nephropathy.     

Combination therapy of trandolapril and candesartan cilexetil reduces microalbuminuria and urinary endothelin-1 excretion in patients with type 2 diabetes

Background. Angiotensin (AT)-converting enzyme inhibitors (ACEIs) and AT1-receptor blockers (ARBs) are widely used to reduce urinary albumin excretion (UAE) and slow the progression of diabetic nephropathy. The aim of the present study was to determine whether treatment with trandolapril (an ACEI) and candesartan cilexetil (an ARB) in combination has more effect on UAE and urinary endothelin (ET)-1 excretion than treatment with trandolapril or candesartan cilexetil alone in patients with type 2 diabetes. Methods. Sixty normotensive type 2 diabetes patients with microalbuminuria were randomly assigned to four treatment groups: (A) treatreatment with trandolapril at 2 mg/day (n = 15), (B) treatment with candesartan cilexetil at 8 mg/day (n = 15), (C) treatment with trandolapril at 2 mg/day and candesartan cilexetil at 8 mg/day (n = 15), and (D) treatment with placebo (n = 15). The study period was 18 months. UAE, urinary ET-1, and plasma ET-1 levels were measured in the patients before treatment and after 12 and 18 months of treatment. Results. Before treatment, UAE, urinary ET-1, and plasma ET-1 levels differed little between the four groups. Trandolapril and candesartan cilexetil administered alone reduced UAE and urinary ET-1 excretion to a similar extent (12 months; P < 0.05 and 18 months; P < 0.01). When trandolapril and candesartan cilexetil were coadministered, UAE and urinary ET-1 excretion decreased to a significantly greater extent at 12 and 18 months (P < 0.05) than with trandolapril or candesartan cilexetil alone. However, plasma ET-1 and systemic blood pressure levels were not affected. Conclusions. The data suggest that combination therapy with trandolapril and candesartan cilexetil has an additive effect on the reduction of microalbuminuria in microalbuminuric normotensive type 2 diabetes patients. Received: December 19, 2001 / Accepted: June 12, 2002     

Polymorphism of the aldosterone synthase gene is not associated with progression of diabetic nephropathy, but associated with hypertension in type 2 diabetic patients

Aim: Inhibition of aldosterone system is beneficial in diabetic nephropathy, and aldosterone synthesis is regulated at the gene-encoding aldosterone synthase (CYP11B2). Considering the role of aldosterone in diabetic nephropathy, genetic polymorphism of this gene may contribute to the development and progression of diabetic nephropathy. In this study, we investigated whether it is associated with diabetic nephropathy in type 2 diabetic patients. Methods: 197 type 2 diabetic patients and 71 healthy controls were enrolled. The study subjects were divided into four groups: healthy controls with normoalbuminuria (n = 71), normoalbuminuric diabetic group (n = 71), microalbuminuric diabetic group (n = 51) and overt proteinuria group (n = 51). Polymorphism of aldosterone synthase gene was determined using standard PCR technique. Results: Higher frequency of TT genotype and T allele in steroidogenic factor-1 (SF-1) binding site and wild type (WT) in intronic conversion (IC) in CYP11B2 was observed in diabetic patients than controls. However, there was no significant difference in SF-1 and IC genotype among diabetic patients according to the state of diabetic nephropathy. Subgroup analysis based on SF-1 polymorphism demonstrated that TT genotype is associated with higher systolic and diastolic blood pressure and higher plasma aldosterone level. In addition, WT in IC genotype showed a significantly higher urinary albumin excretion rate. Plasma aldosterone level was significantly related with systolic blood pressure. Conclusion: Our study suggests that aldosterone synthase gene polymorphism is not associated with progression of diabetic nephropathy, but it may contribute to the development of hypertension associated with increased aldosterone secretion in type 2 diabetic patients.     

The effects of dual blockade of the renin-angiotensin system on urinary protein and transforming growth factor-beta excretion in 2 groups of patients with IgA and diabetic nephropathy

AIMS: The therapeutic benefits of dual blockade of the renin-angiotensin system (RAS) have been inconsistent on renal function and proteinuria. To know the contribution of the heterogeneity of study subjects to such inconsistency, we evaluated the effects of dual blockade of RAS in 2 groups of selected renal diseases, IgA and diabetic nephropathy. To avoid confounding by the blood pressure-reducing effects, angiotensin II receptor antagonists (ATRAs) were added on the patients with long-term, optimally controlled blood pressure taking ACE inhibitors. Twenty-four-hour urinary protein excretion rate and urinary TGF-beta1 level were measured as surrogate markers of renal injury. METHODS: We conducted a prospective crossover trial with 14 IgA and 18 type-2-diabetic nephropathy patients showing moderate degree of proteinuria (> or = 1.0 g/day) and renal dysfunction (creatinine clearance 25 - 75/ml/min). Four to 8 mg once-daily dose of candesartan and placebo were alternatively added on ramipril dose of 5 - 7.5 mg/day for 16 weeks. RESULTS: All baseline data except for the age factor were statistically the same between the 2 disease groups. Twenty-four-hour mean arterial blood pressures were 91.2 +/- 1.6 and 92.3 +/- 1.8 mmHg in IgA and diabetic nephropathy patients respectively at baseline (p = NS). Mean arterial pressure did not change by the addition of candesartan or placebo in both groups. The addition of candesartan (combination) reduced 24-hour urinary protein excretion rate in IgA nephropathy patients with a mean change of -12.3 +/- 4.5%, which is significantly greater compared to a mean change of -0.1 +/- 3.3% after the addition of placebo (placebo) (mean difference 12.4 +/- 5.0, 95% CI 1.2 - 23.5; p < 0.05). Urinary TGF-beta1 level was reduced considerably by the combination therapy, with a -28.9 +/- 6.0% decrease, which was significantly different to that by the placebo, with +4.3 +/- 12.4% (33.3 +/- 13.5, 3.2 - 63.3; p < 0.05). In diabetic nephropathy patients, the addition of candesartan did not reduce 24-hour urinary protein excretion rate. Mean changes of 24-hour urinary protein excretion rate were -0.8 +/- 4.7% by the combination therapy and +0.5 +/- 6.1% by placebo (mean difference 1.3 +/- 4.7, 95% CI -6.8 - 13.5; p < NS). The level of urinary TGF-beta1 was reduced by the combination therapy, with -14.3 +/- 9.5% decrease, but it did not reach statistical significance compared to placebo of +0.7 +/- 15.5% (15.0 +/- 13.5, -14.4 - 44.5; p < NS). The changes in 24-hour urinary protein excretion rate and urinary TGF-beta1 level were neither correlated with each other, nor with the change in mean arterial pressure. Significant changes in the renal function were not detected during the study period. CONCLUSION: Definite beneficial effects of dual blockade of RAS on proteinuria and TGF-beta1 excretion were found in IgA nephropathy patients, which was independent of blood pressure-reducing effect. With our 16-week trial, such benefits were not observed in type 2 diabetic nephropathy. The reduction in urinary TGF-beta1 level suggests that the combination therapy may provide additional renoprotection through the antisclerosing effects. Based on our results, for a proper interpretation the therapeutic effects of the combination therapy should be evaluated separately according to the underlying renal disease.     

Urinary excretion of type IV collagen as a specific indicator of the progression of diabetic nephropathy

AIMS AND METHODS: This study was carried out to clarify whether the urinary excretion of type IV collagen (u-IV collagen) detected by specific radioimmunoassay, can be used as an indicator for the progression of diabetic nephropathy. RESULTS: u-IV collagen was higher in diabetic subjects with microalbuminuria and overt proteinuria than those with normoalbuminuria, IgA nephropathy, membranoproliferative glomerulonephritis, membranous nephropathy, or control normal subjects. u-IV collagen was positively correlated with serum and urinary beta(2)-microglobulin and negatively with creatinine clearance only in diabetic patients, but not in patients with other glomerular diseases. The serum type IV collagen was not different between all the groups, and not correlated with its urinary excretion. In the advanced diabetic nephropathy, immunoreactive type IV collagen was detected in glomerular basement membrane (GBM), tubular basement membrane and Bowman's capsule much more than that in the normal kidney. CONCLUSION: These findings indicated increased production and degeneration of type IV collagen in diabetic nephropathy. It is suggested that augmented turnover of type IV collagen in GBM and tubular basement membrane results in increased concentrations of free u-IV collagen. Therefore, measurement of u-IV collagen may be a useful, specific indicator of the progression of diabetic nephropathy.     

The role of determining the levels of serum collagen type IV in diagnosing early diabetic nephropathy

Two molecules of type IV collagen are linked via the COOH-terminal non-collagenous domain (NCI domain). In this way, type IV collagen forms the main framework of basement membrane. We have developed sandwich Enzyme-Linked Immunosorbent Assay (ELISA) for human serum type IV collage peptide monoclonals for CO5 and CO6 recognizing two different determinants on the central triplex of human collagen molecules. Using this, we explored the possibility that serum levels of type IV collagen (Col IV) are an indicator of early diabetic nephropathy (DN). Serum type IV collagen levels were determined by ELISA in 36 patients with diabetic nephropathy. Serum hemoglobin A1c (HbA1c) and in twenty-four hour urinary albumin excretion rates (UAER) were measured at the same time. A relationship was found between serum levels of this collagen IV and the presence of diabetic nephropathy. That is, serum levels of type IV collagen in diabetic nephropathy were significantly higher than those found in non-insulin-dependent diabetic (NIDDM) patients without nephropathy and in healthy subjects (HS). It is possible that an elevated serum collagen type IV level reflects increased synthetic activity in basement membrane collagen type IV. Serum type IV collagen may be a useful marker for monitoring the dynamics of basement membrane metabolism and in this way serve as a clinical indicator of the progression or the activity of diabetic nephropathy and a marker for the assessment of therapeutic effects.     

Blockade of renin-angiotensin system ameliorates renal injury in NIDDM model rats

Background. Recently, inhibition of the renin-angiotensin system has been reported to be effective for patients with diabetic nephropathy. In this study, we examined the renal protective effects of candesartan cilexetil (TCV-116) in Wistar fatty rats, a model of non-insulin-dependent diabetes mellitus (NIDDM) with renal injuries. Methods. Twelve-week-old Wistar fatty rats received candesartan cilexetil (0.3 or 1 mg/kg) or enalapril (10 mg/kg) daily, administered orally, for 16 weeks. Routine laboratory parameters, such as urinary albumin and total protein excretion, were measured every 4 weeks, and renal function tests and histopathological studies were carried out at the end of the experiment. Results. In the 12-week-old Wistar fatty rats, plasma glucose and insulin levels were significantly higher than those in age-matched Wistar lean rats (normal controls). Urinary albumin and total protein excretion was slightly but significantly increased as compared to these parameters in Wistar lean rats, and increased further with time. Daily administration of candesartan cilexetil or enalapril inhibited the increase in urinary albumin and total protein excretion without affecting plasma glucose and insulin levels. In histopathological studies, candesartan cilexetil (0.3 and 1 mg/kg) and enalapril (10 mg/kg) prevented the glomerular injury observed in vehicle-treated rats. Candesartan cilexetil (1 mg/kg) and enalapril also inhibited tubular changes. Systolic blood pressure in the drug-treated groups was significantly decreased compared with that in vehicle-treated rats. Conclusions. Inhibitors of the renin-angiotensin system ameliorated proteinuria and the pathological changes of renal injuries in this NIDDM model. Candesartan cilexetil may be useful for the treatment of NIDDM patients with renal damage. Received: March 1, 1999 / Accepted: June 13, 2000     

The role of the pediatric nephrologist in the care of children with diabetes mellitus

The pediatric nephrologist has traditionally not been involved in the care of the diabetic child since diabetic nephropathy presents in adulthood. Recent studies suggest that diabetic kidney disease develops silently during childhood. Measurement of urinary albumin excretion (UAE) allows earlier detection of patients at risk of nephropathy, often in adolescence. In addition to diabetic nephropathy, diabetic children are at risk of urinary tract infections, renal papillary necrosis, and various forms of glomerulonephritis. The role of the pediatric nephrologist in the care of the child with diabetes might include advising on the administration and interpretation of screening for UAE and the measurement and interpretation of glomerular filtration rate, and blood pressure. Children with evidence of renal dysfunction should be evaluated and treated by the pediatric nephrologist. Frequently, renal biopsy will be necessary in these patients. Future research may allow the detection of diabetic kidney disease earlier in childhood, further expanding the role of the pediatric nephrologist. In particular, early renal biopsy may eventually be used to select those patients at risk of diabetic nephropathy for specific treatment alterations.     

Combination of Pentoxifylline with Angiotensin Converting Enzyme Inhibitors Produces an Additional Reduction in Microalbuminuria in Hypertensive Type 2 Diabetic Patients

Objective.?To investigate the anti proteinuric effect of pentoxifylline in diabetic patients, we prospectively studied in 25 hypertensive type 2 diabetic patients with persistent microalbuminuria and normal renal function the impact of combining pentoxifylline with an angiotensin converting enzyme inhibitor, lisinopril, on urinary albumin excretion and compared the results with those obtained in a control group of 25 type 2 diabetic patients treated with lisinopril only. Material and Methods.?Fifty hypertensive type 2 diabetic patients with persistent microalbuminuria (31 males and 19 females, aged between 47–73 years) were randomly assigned to two groups. Group A received lisinopril 10 mg/day, while group B was given lisinopril 10 mg/day and pentoxifylline 600 mg/day for nine months. There were no significant differences between serum creatinine, HbA1c, blood pressure and urinary albumin excretion in both groups (p>0.05). Results.?Serum creatinine, creatinine clearance, blood pressure, HbA1c levels did not change significantly during the study. Urinary albumin excretion decreased from 228 ± 28 to 148 ± 15 mg/day in group A (p<0.05). In group B urinary albumin excretion decreased from 219 ± 26 to 128 ± 12 mg/day (p<0.05). Pentoxifylline and lisinopril combination caused a significant additional reduction in urinary albumin excretion when compared to lisinopril regimen (p<0.05).

Conclusions.?Our findings suggest that the combination of pentoxifylline with an angiotensin converting enzyme inhibitor in hypertensive type 2 diabetic patients with persistent microalbuminuria causes a significant reduction in urinary albumin excretion and this effect seems independent from blood pressure and glycemic control.     

Exenatide Reduces Urinary Transforming Growth Factor-β(1) and Type IV Collagen Excretion in Patients with Type 2 Diabetes and Microalbuminuria

Aims: It was reported that exenatide ameliorated renal injury in diabetic rats. The present study was carried out to evaluate the effect of exenatide on 24-hour urinary albumin, urinary transforming growth factor-β(1) (TGF-β(1)) and type IV collagen excretion in patients with type 2 diabetes and microalbuminuria. Methods: 31 type 2 diabetic patients with microalbuminuria were randomly allocated to receive exenatide (group Exe, n = 13) or glimepiride treatment (group Glm, n = 18) for 16 weeks. Body mass index (BMI), fasting plasma glucose, 2-hour postprandial plasma glucose, glycated hemoglobin A(1c), systolic blood pressure, diastolic blood pressure, 24-hour urinary albumin, urinary TGF-β(1) and type IV collagen concentration were analyzed between the two treatment groups. 20 age- and BMI-matched healthy subjects were chosen as the normal control group (group NC, n = 20). Results: After 16 weeks of treatment, 24-hour urinary albumin, urinary TGF-β(1) and type IV collagen in group Exe were significantly lower than those of group Glm (p < 0.01), while glycemic control had no statistical difference between the two groups. Conclusions: Our results indicate that exenatide reduces urinary TGF-β(1) and type IV collagen excretion in patients with type 2 diabetes and microalbuminuria, which may be partly contributory to its directly renoprotective role.     

Serum type IV collagen concentrations in diabetic patients with microangiopathy as determined by enzyme immunoassay with monoclonal antibodies.

In long-term diabetes mellitus, thickening of basement membrane in capillaries and small vessels is a characteristic lesion and plays an important role in the progression of diabetic microangiopathy. We have developed a sandwich enzyme immunoassay for human serum type IV collagen peptide with monoclonal antibodies. Previous studies suggested that collagen levels reflect the activity of fibrogenesis in basement membrane. Serum type IV collagen levels were measured in 137 non-insulin-dependent diabetic patients (aged 50-75 yr) with or without clinical signs of retinopathy, nephropathy, and/or neuropathy and 110 healthy subjects (aged 50-75 yr) without serological abnormality. Serum concentrations of type IV collagen were significantly higher (P less than 0.01) in diabetic patients (mean +/- SE 124.1 +/- 4.1 ng/ml) than in healthy subjects (73.9 +/- 2.2 ng/ml) and were increased with the prevalence or incidence of diabetic complications. In the patients with diabetic microangiopathy, serum type IV collagen levels became higher as clinical signs worsened. Especially in the patients with diabetic nephropathy, serum type IV collagen levels became higher with elevation of blood urea nitrogen, serum creatinine, and serum beta 2-microglobulin but not urinary excretion of beta 2-microglobulin and N-acetyl-beta-glucosaminidase. These observations indicated that elevation of serum type IV collagen in diabetic nephropathy was related to glomerular filtration dysfunction rather than renal tubular dysfunction. However, the antigen, which can be detected by our assay system, did not exist in urine specimens of healthy subjects, and an intimate relationship was not observed between serum type IV collagen level and serum creatinine level.(ABSTRACT TRUNCATED AT 250 WORDS)     

How to predict nephropathy in type 1 diabetic patients

OBJECTIVE: Do exaggerated increases in blood pressure and albuminuria during exercise occur earlier than microalbuminuria and which type of test is most predictive of diabetic nephropathy? MATERIAL AND METHODS: A total of 33 insulin-dependent normoalbuminuric men (mean duration of diabetes 14 years; mean age 28 years) and 34 age-matched apparently healthy control subjects were studied. Urinary albumin excretion, heart rate and blood pressure were measured during fixed workload (150 W) and fixed heart rate (155 beats/min) tests. Mean follow-up time was 13.1 +/- 3.2 years. A urinary albumin level in early-morning urine persistently >30 mg/l was considered a sign of diabetic nephropathy. RESULTS: Sixteen patients reached the endpoints of the study. Eleven had developed microalbuminuria and five macroalbuminuria (persistent levels of urinary albumin >300 mg/l). Of the latter patients, two needed dialysis. Systolic blood pressure and albumin excretion during the fixed heart rate test were higher in diabetic patients who developed signs of nephropathy than in control subjects and diabetic subjects with persistent healthy kidneys. Such differences were not found in the fixed workload test. There were no differences in glycated haemoglobin, blood pressure levels or albumin excretion at baseline between the two diabetic groups. CONCLUSIONS: To predict the development of diabetic nephropathy it seems important to choose a fixed heart rate test. High levels of systolic blood pressure in such a test were associated with the development of micro- and macroalbuminuria.     

Relationship between urinary albumin excretion and glomerular filtration rate in normotensive, nonproteinuric patients with type 2 diabetes mellitus

BACKGROUND/AIM: In patients with type 2 diabetes mellitus, the relationship between glomerular filtration rate (GFR) and urinary albumin excretion remains an unresolved issue. In order to investigate the early renal function abnormalities, GFR and urinary albumin excretion were assessed, and their relationship was examined in normotensive patients with type 2 diabetes mellitus. METHODS: In a cross-sectional study of 85 nonhypertensive Japanese patients with type 2 diabetes mellitus not showing overt proteinuria, the GFR was measured using (99m)Tc-diethylenetriamine pentaacetate renography. Fifty-one diabetic patients lacked microalbuminuria (albumin excretion <30 mg/day), while 34 patients showed microalbuminuria (between 30 and 300 mg/day). Fifteen healthy subjects served as controls. RESULTS: The three groups were well matched with regard to gender, age, and body mass index. The GFR in microalbuminuric patients (134 +/- 23 ml/min/1.48 m(2)) was significantly higher than in patients without microalbuminuria (108 +/- 21 ml/min/1.48 m(2)) and in controls (109 +/- 18 ml/min/1.48 m(2); p < 0.0001). In type 2 diabetic patients, the GFR positively correlated with the logarithmically transformed urinary albumin excretion. Multiple regression analysis showed that the urinary albumin excretion was significantly and independently affected by GFR (beta = 0.548), duration of diabetes (beta = 0.297), and systolic blood pressure (beta = 0.232; R(2) = 0.409; p < 0.0001). CONCLUSION: It is suggested that one of the mechanisms underlying increased urinary albumin excretion in early nephropathy in normotensive type 2 diabetes is glomerular hyperfiltration.     

A study of Tamm-Horsfall protein excretion in hypertensive patients and type 1 diabetic patients.

OBJECTIVE: The study was performed in order to evaluate to what extent hypertension or diabetes mellitus may affect the urinary excretion rate of Tamm-Horsfall protein. MATERIALS AND METHOD: The urinary excretion rates of albumin and Tamm-Horsfall protein, a measure of glomerular and distal tubular function, respectively were measured in patients with essential hypertension (n = 17) and in type 1 diabetes with (n = 20) or without nephropathy (n = 8) and in apparently healthy subjects (n = 10). RESULTS: Mean 24-h ambulatory blood pressure measurements showed higher blood pressure levels in the hypertensive (167/ 106 mmHg, p < 0.001) than in the diabetic patients with (136/84 mmHg) and without nephropathy (121/74 mmHg) and in healthy subjects (122/76 mmHg). Day and night ratios of systolic and diastolic blood pressure levels were not different among the four groups. Urinary albumin excretion rate was increased in patients with hypertension (30.8 x/ 3.4 microg/min; geometric mean x/tolerance factor; p < 0.001) and diabetes with nephropathy (462 x/ 3.5 microg/min; p < 0.001) compared with diabetic patients without nephropathy and healthy subjects (4.6 x/ 1.9 and 3.7 x/ 1.5 microg/min, respectively). The Tamm-Horsfall protein excretion rate was decreased in patients with diabetic nephropathy (11.6 x/ 3.5 microg/min) compared to patients with hypertension (36.3 x/2.1 1g/min; p < 0.01), diabetes without nephropathy (39.2 x/ 2.0 microg/min; p < 0.05) and healthy subjects (63.0 x/ 1.4 microg/min; p < 0.001), whereas no differences were found among the latter three groups. CONCLUSION: These data indicate that high blood pressure may be associated with albuminuria, while a decrease in excretion rate of Tamm-Horsfall protein may be associated with diabetic nephropathy. These associations need to be studied in a larger population.     

Urinary type IV collagen excretion reflects renal morphological alterations and type IV collagen expression in patients with type 2 diabetes mellitus

AIM: We tried to establish the significance of quantifying urinary type IV collagen (IV-C) excretion for the evaluation of renal involvement of type 2-diabetic patients. METHODS: Twenty patients (13 males and 7 females; age range 31 to 69 years) with type 2 diabetes mellitus had undergone renal biopsy and relationship between the severity of morphological alteration, IV-C expression and urinary IV-C excretion were examined. RESULTS: Urinary IV-C excretion significantly correlated with mesangial expansion score (p = 0.49, p < 0.05) and tubulointerstitial injury score (p = 0.56, p < 0.05). Furthermore, urinary IV-C excretion significantly correlated with both glomerular (r = 0.56, p < 0.01) and tubulointerstitial IV-C expression areas. Urinary protein excretion also correlated with mesangial expansion score and tubulointerstitial injury score. However, it did not correlate with the expression of IV-C in the kidney. CONCLUSIONS: These results suggest that urinary IV-C excretion reflects the pathogenetic process of diabetic nephropathy, which urinary protein excretion alone cannot do sufficiently. It can be concluded that urinary IV-C excretion could be a more useful marker for the evaluation of renal involvement of type 2-diabetic patients.     

Endocan and albuminuria in type 2 diabetes mellitus

Background: Endocan is a newly identified proteoglycan released from endothelium, stimulating angiogenesis and when increased, indicates endothelial activation (inflammation). Our aim was to examine the association between serum endocan levels and urine albumin–creatinine ratio (UACR).

Method: One hundred and thirty-seven patients with type 2 diabetes mellitus and normal serum creatinine who had no co-morbidities other than hypertension, diabetic nephropathy, retinopathy, or neuropathy were divided into normoalbuminuria (G1), microalbuminuria (G2), and macroalbuminuria (G3) groups and compared cross-sectionally regarding serum endocan levels.

Result: There were 55, 47, and 35 patients in G1, G2, and G3, respectively. The groups were comparable in terms of gender, age, duration of diabetes, diabetic neuropathy/retinopathy, fasting glucose, HbA1c, serum creatinine level, and eGFR. Patients in G3 had significantly higher blood pressure but lower serum albumin and endocan levels. UACR showed a negative bivariate correlation with serum endocan levels (r?=??.282, p?=?.001). There was bivariate positive correlation between endocan and systolic blood pressure (r=.185, p?=?.030). In linear regression analysis, UACR was negatively correlated with endocan while positively correlated with systolic blood pressure, duration of diabetes, and platelet distribution width.

Conclusion: Patients with macroalbuminuria had lower endocan levels, and increasing UACR was associated with decreasing serum endocan levels. Despite the occurrence of angiogenesis and glomerular hypertrophy in the early phase of diabetic nephropathy, ensuing significant renal injury over time may reduce the expression of endocan. Serum endocan levels may represent a novel marker for nephropathy progression.     

Urinary angiotensin-converting enzyme 2 in patients with CKD

Aim: Angiotensin‐converting enzyme 2 (ACE2) is a type I membrane protein that antagonizes the action of angiotensin II. Because of the need for invasive kidney biopsy, little is known about the role of renal ACE2 in human kidney diseases. The authors studied if urinary ACE2 could provide a novel clue to renal ACE2 in chronic kidney disease (CKD). Methods: Subjects were 190 patients with CKD including 38 patients with diabetic nephropathy and 36 healthy subjects. Parameters were urinary ACE2 by enzyme‐linked immunosorbent assay, blood pressure, casual plasma glucose, proteinuria, microalbuminuria, serum creatinine and estimated glomerular filtration rate. Urine and serum samples were also subjected to western blotting of ACE2. Results: Western blotting confirmed increased urinary ACE2 levels in patients with CKD. Urinary ACE2 was significantly higher in patients with CKD than healthy subjects (median 9.64 (interquartile range, 4.41–16.89) vs 1.50 (0.40–2.33) mg/g·creatinine, P < 0.001) and in patients with diabetic nephropathy than patients without diabetic nephropathy (median 13.16 (interquartile range 6.81–18.70) vs 8.90 (4.19–16.67) mg/g·creatinine, P < 0.05). No significant difference in urinary ACE2 was observed by the use of angiotensin‐converting enzyme inhibitor and angiotensin receptor blocker. Conclusion: Urinary ACE2 could be used as a non‐invasive marker to understand the role of renal ACE2 in CKD.     

Prevention and treatment of diabetic nephropathy with blood pressure lowering drugs

Summary: Diabetic nephropathy is a clinical syndrome characterized by persistent albuminuria (>300 mg/24 h), a relentless decline in glomerular filtration rate (GFR), and raised arterial blood pressure. the prevalence of abnormal elevated albumin excretion rate (>30 mg/24 h) is approximately 40% in insulin-dependent (IDDM) and non-insulin-dependent (NIDDM) patients. Diabetes has become the leading cause of end-stage renal failure in the United States of America and Japan and it remains the second leading cause in Europe. Patients suffering from diabetic nephropathy have an enormous increase in morbidity and mortality from cardiovascular disease in addition to renal death. Elevated blood pressure is an early and frequent phenomenon and furthermore accelerates the course of diabetic nephropathy. Studies in humans suggest that angiotensin-converting enzyme (ACE) inhibitors postpone and may even prevent progression to clinical overt diabetic nephropathy in normotensive IDDM and NIDDM patients with persistent microalbuminuria. Conventional antihypertensive therapy and ACE inhibition usually combined with a diuretic reduces albuminuria and postpones renal insufficiency in hypertensive IDDM patients with overt nephropathy. A more beneficial effect on the rate of decline in glomerular filtration rate has been demonstrated by ACE inhibitors compared to conventional antihypertensive treatment in IDDM patients with diabetic nephropathy and reduced kidney function (serum creatinine >133 mmol/L). These findings suggest that ACE inhibition causes renal protection (i.e. a beneficial effect on kidney function [structure] above and beyond what would be expected from blood pressure lowering effect alone). Finally, it should be stressed that ACE inhibition and conventional antihypertensive treatment postpone end-stage renal failure and improve survival in diabetic nephropathy.     

Angiotensin-converting enzyme inhibitors and probucol suppress the time-dependent increase in urinary Type IV collagen excretion of Type II diabetes mellitus patients with early diabetic nephropathy

BACKGROUND: A multicenter prospective clinical trial was carried out in 9 National Hospitals in Japan to elucidate the time-dependent change in urinary Type IV collagen excretion rate of Type II diabetes mellitus (DM) patients, and to investigate whether an angiotensin-converting enzyme inhibitor (ACE-I) or probucol is effective in preventing progression of renal involvement of diabetics by evaluating urinary Type IV collagen excretion. METHODS: Normo- and microalbuminuric patients with Type II DM were recruited. Patients were assigned to either the control (n = 88), ACE-I (n = 43) or probucol (n = 37) group and treated for 24 months. Besides albumin excretion rate (AER), urinary Type IV collagen excretion rate was also measured. RESULTS: Although, AER, urinary N-acetyl-beta-D-glucosaminidase and beta2-microglobulin excretion rates in the control group did not vary over 24 months, urinary Type IV collagen excretion rate in the control group increased time-dependently (p < 0.01 vs baseline at 18 months and p < 0.005 vs baseline at 24 months). In the ACE-I and probucol groups, time-dependent increases in urinary Type IV collagen excretion rates were not observed. In the ACE-I group, the urinary Type IV collagen excretion rate was significantly lower than that in the control group at 24 months (p < 0.05). In the probucol group, the urinary Type IV collagen excretion rate was significantly lower than that in the control group at 6 months (p < 0.05). In the ACE-I group, AER decreased significantly compared with baseline at 18 months (p < 0.05) and at 24 months (p < 0.005). CONCLUSIONS: ACE-I has a beneficial effect and probucol may have a beneficial effect in preventing the progression of early diabetic nephropathy. Measurement of the urinary Type IV collagen excretion rate in combination with AER would be useful for the management of early renal involvement in Type II DM.     

Vitamin D receptor activation with calcitriol for reducing urinary angiotensinogen in patients with type 2 diabetic chronic kidney disease

Background Recently, it has been reported that urinary angiotensinogen levels is a specific index of the intrarenal renin-angiotensin-aldosterone system (RAAS) status and it is significantly correlated with urinary albumin:creatinine (Cr) ratio in hypertensive patients. The aim of the present study was to assess the effect of activation of the Vitamin D receptor with calcitriol on albuminuria and urinary angiotensinogen as a novel biomarker of the intra-renal RAAS status in patients with diabetic nephropathy (DN). Methods Ninety-eight patients with type 2 diabetes and albuminuria who were treated with RAAS inhibitors (angiotensin-converting enzyme inhibitor (ACE-i) or angiotensin receptor blocker (ARB)) have participated in this study. Patients were randomized to receive either placebo (n?=?50) or 0.25?μg/day calcitriol (n?=?48). We have examined urinary albumin:Cr ratio and urinary angiotensinogen:Cr ratio before and 24 weeks later after treatment in both group. Results The mean urinary albumin:Cr ratio and urinary angiotensinogen:Cr ratio were significantly higher in patients with DN than in normal controls (p?0.001). Urinary angiotensinogen:Cr ratio was significantly, positively correlated with urinary albumin:Cr ratio in both groups (in the placebo group; p?=?0.01, r?=?0.4236, in calcitriol group; p?=?0.01, r?=?0.4564). Conclusion These data indicated that administration of Vitamin D receptor activator in combination with RAAS inhibitors had an additional benefit in lowering albuminuria in patients with DN. More pronounced reduction of urinary albumin:Cr ratio that was positively correlated with angiotensinogen:Cr ratio in calcitriol group suggested that Vitamin D receptor activation might blunt albuminuria by reducing urinary angiotensinogen levels reflecting intra-renal RAAS status.