Changes In Diabetic Nephropathy Research Articles

Early histopathological changes in diabetic nephropathy.

Early histopathological changes in diabetic nephropathy.

Changes in the Expression of Nephrin Gene and Protein in Experimental Diabetic Nephropathy

Diabetic nephropathy is a major complication of diabetes leading to thickening of the glomerular basement membrane, glomerular hypertrophy, mesangial expansion, and overt renal disease. The pathophysiologic mechanisms of diabetic nephropathy remain poorly understood. Nephrin is a recently found podocyte protein crucial for the interpodocyte slit membrane structure and maintenance of an intact filtration barrier. Here we have assessed the role of nephrin in two widely used animal models of diabetes, the streptozotocin model of the rat and the nonobese diabetic mouse. In both models, the expression levels of nephrin-specific mRNA as determined by real-time quantitative polymerase chain reaction increased up to two-fold during several weeks of follow-up. Immunohistochemical stainings revealed nephrin also more centrally within the glomerular tuft along with its preferential site in podocytes. Interestingly, as detected by immunoblotting, nephrin protein was also found in the urine of streptozotocin-induced rats. We conclude that nephrin is connected to the early changes of diabetic nephropathy and thus may contribute to the loss of glomerular filtration function.

Atherogenic lipoprotein changes in diabetic nephropathy

Cardiovascular risk is increased in patients with diabetic nephropathy. The aim of this study was to examine the relative impacts of albuminuria and renal failure, the two important features of diabetic nephropathy, on potentially atherogenic lipoprotein changes in this condition. The subjects were 160 non-diabetic healthy controls and a total of 200 type 2 diabetes patients with various degrees of nephropathy. The diabetic patients were divided into four groups by urinary albumin/creatinine ratio (U-ACR) and serum creatinine (S-Cr) levels: DM-1 ( U-ACR<30 mg/g, N=85), DM-2 ( U-ACR=30 –300 mg/g, N=48), DM-3 ( U-ACR>300 mg/g, N=29) and DM-4 ( S-Cr>177 μmol/l or 2.0 mg/dl, N=38). Lipids in very low (VLDL), intermediate (IDL), low (LDL), and high density (HDL) lipoproteins were measured following ultracentrifugation. VLDL-cholesterol (VLDL-C) was elevated (by 73–100%) in diabetic patients and it did not differ among the stages of nephropathy. IDL-C was higher as the nephropathy stage was advanced, and the elevation was significant in the DM-3 (by 75%) and DM-4 (by 131%) groups. LDL-C was not elevated in diabetic patients and was not different among the stages of nephropathy. Reduction of HDL-C was significant in DM-1, DM-2 and DM-3 (by 12–16%) and it was more exaggerated in DM-4 (by 35%). Multiple regression analyses indicated that elevated S-Cr, but not U-ACR, was an independent factor associated with raised IDL-C and lowered HDL-C in diabetic patients. These results indicate that diabetic patients with nephropathy show multiple lipoprotein changes, and that renal failure has greater impact than albuminuria on abnormalities in IDL and HDL. These lipoprotein alterations may contribute to an increased cardiovascular risk in diabetic nephropathy, especially in diabetic renal failure.

Duplex sonographic registration of age and diabetes-related loss of renal vasodilatory response to nitroglycerine.

Nitroglycerine effects dilatation of the vas afferens in the kidney by its active metabolite nitric oxide (NO). In diabetic nephropathy, NO appears to cause hyperfiltration and proteinuria. The aim of this study was to investigate the potential of duplex Doppler ultrasonography in recording changes in resistive indices following nitroglycerine and whether the extent of changes in diabetic nephropathy is reduced as a result of the arteriolar dilatation mediated by NO. Fifty-three subjects made up three groups: group 1, 12 young healthy volunteers (5 male, 7 female, 28+/-6 years); group 2, 21 older healthy volunteers (7 male, 14 female, 62+/-8 years); group 3, 20 patients (13 male, 7 female, 56+/-18 years) with mild diabetic nephropathy. The resistive index (RI) was measured in the interlobar arteries before, and 1, 3 and 5 min after administration of 0.8 mg sublingual nitroglycerine. The initial RI of 0.592 decreased in group 1 by 10.8% (P<0. 01) after nitroglycerine, in group 2 the initial figure of 0.631 decreased by 5.9% (P<0.01), and in group 3 the initial figure of 0. 669 decreased by 3.4% (P<0.01). Initial RI values differed significantly between groups 1 and 3 (P<0.01) and groups 1 and 2 (P<0.01), as did values between all healthy volunteers (groups 1 and 2, n=33) and patients with nephropathy (P<0.005). The extent of DeltaRI differed significantly between groups 1 and 3 (P<0.01), 1 and 2 (P<0.02), and between all volunteers and group 3 (P<0.003). In groups 1 and 2 the initial RI was dependent on age (P<0.03), in group 3 on age and creatinine clearance (P<0.02 and P<0.05 respectively). DeltaRI correlated with age in the healthy subjects (P<0.01) and with duration of diabetes in diabetic nephropathy (P0. 03). Haemodynamic changes in renal perfusion caused by nitroglycerine can be detected using duplex ultrasonography. In healthy subjects, DeltaRI declines with increasing age. In diabetic nephropathy patients, the response to nitroglycerine is reduced. The increased initial RI in such patients suggests fixed arteriolar damage.

Glycosaminoglycans: use in treatment of diabetic nephropathy.

Glycosaminoglycans: use in treatment of diabetic nephropathy.

Size and Charge Selectivity of the Glomerular Filter in Patients with Insulin-Dependent Diabetes mellitus: Urinary Immunoglobulins and Glycosaminoglycans

Background: In diabetic nephropathy, a reduction in negative membrane charge in the glomerular filter, i.e., the number of sulphated groups of glycosaminoglycans, has been argued to lead to increases in excretion of negatively charged molecules, such as albumin and IgG4. However, albuminuria and an increased excretion rate of IgG may also be caused by an increase in radius or number of glomerular large pores. Methods: Timed urinary excretion rates of sulphated glycosaminoglycans, albumin, and IgG2, IgG4, and IgM were analyzed in 94 patients with insulin-dependent diabetes mellitus with different degrees of nephropathy and compared with the excretion rates in 26 control subjects. Sulphated glycosaminoglycans were measured spectrophotometrically after addition of 1,9-dimethylmethylene blue. Albumin and immunoglobulins were measured by immunoassays. Results: With increases in the albumin excretion rate the excretion of IgG2, IgG4, and IgM also increased, in contrast to a decrease in glycosaminoglycans and the ratio between IgG2 and IgG4 (selectivity index). This index decreased from 6.2 to 0.7 (median; p < 0.01). However, with linear regression analysis the excretion rates of albumin and immunoglobulins were not associated with those of glycosaminoglycans. Conclusion: In diabetic nephropathy changes in both large-pore number and in charge selectivity may be pathogenic mechanisms for albuminuria.

The three-dimensional ultrastructure of diabetic glomeruli revealed by the quick-freezing and deep-etching method

The three-dimensional ultrastructure of the glomerular basement membrane (GBM) and mesangial matrix (MM) in streptozotocin (STZ)-induced diabetic rats and in one case of a human diabetic nephropathy were examined using the quick-freezing and deep-etching method. In the diabetic rats, the GBM inner layer was diffusely enlarged, and the meshwork structures in the GBM middle layer and the MM were markedly irregular due to the rupturing of fine fibrils. These irregularities and enlargements of the mesh pores in the diabetic rats developed during the experimental period and were significantly different from those in the control rats. Insulin treatment after STZ injection significantly prevented ultrastructural changes in the GBM and MM. The human diabetic case was a 69-year-old male who had been suffering from non-insulin dependent diabetes mellitus for 29 years. He had a background diabetic retinopathy, microalbuminuria and a decrease in lower limb tendon reflexes. Conventional electron microscopy revealed electron-lucent areas in enlarged subendothelial spaces and mesangium. By the quick-freezing and deep-etching method, the GBM inner layer was diffusely enlarged, and the meshwork structure of the GBM middle layer and the MM showed marked irregularity due to the rupturing of fine fibrils. These findings suggest that the initial morphological changes in diabetic nephropathy include structural abnormalities of fine fibrils in the GBM and MM, which may correspond to the subendothelial and mesangial electron-lucent areas as observed in conventional ultrathin sections.

Synthesis of type III Collagen and type IV collagen by tubular epithelial cells in diabetic nephropathy

Overproduction of extracellular matrix (ECM) is considered to be primarily responsible for both glomerular and tubulointerstitial (TI) changes in diabetic nephropathy (DN). To clarify the possible role of the collagens in TI damage in DN, type III interstitial collagen and type IV basement membrane collagen were studied in 10 cases of DN and 10 control cases by immunohistochemistry and in situ hybridization techniques. In control cases, no immunostaining for type III collagen was found in the renal tubules, while strongly positive in the adjacent interstitium. On the other hand, type IV collagen was found weakly in the tubular basement membrane (TBM) in control cases. In DN, increased immunostaining for both type III and type IV collagens were found in the damaged tubulointenstitium (TI). To determine the sources of these collagens in TI damage, non-radioactive in situ hybridization was performed utilizing thymine-thymine (T-T) dimerized synthetic oligonucleotides complementary to either human pro alpha 1 (III) chain or pro alpha 1 (IV) chain mRNA as probe. In normal tubules, tubular epithelial cells were not uniformly but persistently positive for pro alpha 1 (IV) mRNA. Meanwhile, no specifically detectable positive hybridization signals for pro alpha 1 (III) mRNA was found in the normal tubular epithelial cells. Accelerated synthesis of both type III and type IV collagens by tubular epithelial cells was noted in TI damage in DN. From the results we concluded that excessive synthesis of both type III and type IV collagens by tubular epithelial cells might significantly contribute to the TI damage found in DN.

In situ hybridization of interleukin 6 in diabetic nephropathy.

Increased mesangial expansion is one of the most characteristic histological changes in diabetic nephropathy (DN). Although the pathogenesis of DN remains unclear, recent studies associate interleukin (IL) 6 with mesangial proliferative glomerulonephritis. To elucidate the expression and localization of IL-6 mRNA in renal tissues of patients with DN, a high-resolution in situ hybridization using digoxigenin-labeled oligonucleotide was performed. Patients were divided into three groups based on light microscopy findings: mild (group 1), moderate (group 2), and severe (group 3) mesangial expansion. The relationship between the expression of IL-6 mRNA and the degree of glomerular mesangial expansion in DN was examined. Individual cells positive for IL-6 mRNA were observed in glomeruli. These cells were mesangial cells, glomerular epithelial cells, and Bowman's capsule. The signal intensity was strongest in tissues from group 2 but was weak in those from groups 1 and 3. Most cells in the area of mesangial proliferation were strongly stained for IL-6 mRNA, and few positive cells were found in the Kimmelstiel-Wilson nodular lesion. In the interstitium, some tubules, particularly atrophic tubules, and some infiltrating cells were positively stained for IL-6 mRNA. The interstitial expression of IL-6 mRNA correlated significantly with the degree of interstitial injury and was remarkable in tissues from groups 2 and 3. We conclude that IL-6 mRNA is expressed by glomerular resident cells and interstitial cells in the renal tissue of patients with DN and that its expression may be associated with mesangial proliferation and may be involved in the tissue injury of DN.

Effects of somatostatin and captopril on glomerular prostaglandin E 2 production in normal and diabetic rats

Somatostatin (SRIH) has recently been shown to be effective in reversing many of the early changes of diabetic nephropathy. It is unknown whether SRIH exerts its protective effects via its ability to suppress growth hormone (GH) or via other direct renal effects. Since changes in glomerular prostaglandin (PG) E 2 production are thought to be an important part of the underlying pathophysiology of diabetic nephropathy, we sought to determine if SRIH altered glomerular PG E 2 production in the rat. Whole glomeruli isolated from streptozotocin-diabetic rats and from controls were incubated with either saline, captopril, or varying concentrations of SRIH, and PG E 2 production was determined by direct radioimmunoassay of media. Incubation with captopril (10 −4M) resulted in equivalent increases in PG E 2 production in glomeruli from both control and diabetic rats (140.8±12.8% and 150.2±18.9% respectively). Incubation with high concentrations of SRIH (10 −6M) also resulted in significant increases in glomerular PG E 2 production in both diabetic and control rats. However, at low SRIH concentrations (10 −10M), glomerular PG E 2 production was increased only in the diabetic rats (167.0±11.4% vs 95.3±9.2% in normals). We conclude that SRIH increases glomerular PG E 2 production, and that glomeruli from diabetic rats appear to be more sensitive to lower concentrations of SRIH when compared to normal rats. It is possible that this effect on PG E 2 production may underlie the favorable effects of SRIH on the glomerulus in diabetes.

INCIPIENT DIABETIC NEPHROPATHY IN IDDM ADOLESCENTS: MICROALBUMINURIA PRECEDES THE RISE IN SYSTEMIC BLOOD PRESSURE

The temporal relationship between the onset of diabetic nephropathy and the development of systemic hypertension remains uncertain. Our aim was to evaluate whether differences in systemic BP in IDDM adolescents with (MA) and without (nMA) microalbuminuria could be detected by ambulatory blood pressure monitoring (aBPm). 20 IDDM adolescents (9 MA, 11 nMA), well matched for sex, age (MA 17.1±1.8yr, nMA 17.3 ±1.5 yr), body mass index (23.3±2.2 and 24.3±3.0 kg/m2) and IDDM duration (8.8±4.2 and 8.2±3.6 yr). HbA1c (9.4±2.0 and 8.6±1.3%), and creatinine clearance (1.46±0.77 and 1.63±0.42 ml/s/1.73 m2) were similar in the 2 groups; they differed only in albumin excretion rate: MA group 111 ± 171, nMA group 6.2±3.7 ng/min (p 95th percentile for age: there were no significant differences in any of the BP measurements. The % sBP >95th percentile tended to be higher in those with MA.(28±25%) than those in the nMA (15±15) group, but this difference was not statistically significant. Other studies have shown significant BP differences in aBPm in IDDM subjects with and without MA; however, these subjects were older and had longer duration disease. Our data suggest, however, that systemic hypertension may be a consequence of the earliest changes of diabetic nephropathy and not a prerequisite for its development. A longitudinal study is warranted to assess changes in aBPm profiles in these individuals as they progress towards overt nephropathy.

Heterogeneous nature of renal lesions in type II diabetes.

The nature of renal damage in patients with type II diabetes remains unclear. This study was directed to evaluate pathologic changes in 52 patients affected by type II diabetes with overt clinical nephropathy by conventional and morphometric techniques. The duration of diabetes ranged from 6 to 384 months, urinary protein excretion ranged from 0.9 to 9.2 g/24 h, and serum creatinine ranged from 0.9 to 9 mg/dL. Specimens were examined semiquantitatively by light microscopy, immunofluorescence, and electron microscopy. Glomerular tuft cross-sectional area was measured by a versatile computer system. Pathologic examination revealed three distinct patterns arbitrarily defined as Classes 1, 2, and 3. Class 1 included 19 patients with typical changes of diabetic nephropathy characterized by a high score of glomerulosclerosis (mean score, 2.1), marked glomerular hypertrophy (23,632 microns2), and arteriolar hyalinosis (mean score, 2). There was a positive correlation between glomerulosclerosis and arteriolar hyalinosis scores (P < 0.05). Class 2 included 16 patients showing chronic and aspecific changes. As compared with Class 1 patients, these patients had less glomerulosclerosis (mean score, 1.3) and less arteriolar hyalinosis (mean score, 0.8) but more severe ischemic glomerular lesions (mean score, 1.4) and arteriosclerosis (mean score, 2). Class 3 included 17 patients showing glomerular disease superimposed on diabetic glomerulosclerosis. There were no differences in age, mean duration of diabetes, renal function, urinary protein excretion, and mean arterial pressure among the three classes of patients. This study indicates that renal lesions in patients with type II diabetes manifest in a quite heterogeneous fashion.(ABSTRACT TRUNCATED AT 250 WORDS)

Cell biology and the functional changes of diabetic nephropathy.

Journal Article Cell biology and the functional changes of diabetic nephropathy Get access E. N. Wardle E. N. Wardle Search for other works by this author on: Oxford Academic PubMed Google Scholar Nephrology Dialysis Transplantation, Volume 7, Issue 9, 1992, Pages 889–895, https://doi.org/10.1093/ndt/7.9.889 Published: 01 January 1992 Article history Received: 26 November 1991 Published: 01 January 1992 Revision received: 10 April 1992

Prevention of glomerular basement membrane thickening by aminoguanidine in experimental diabetes mellitus

The etiology of diabetic glomerulopathy appears to be related, at least in part, to the degree of hyperglycemia, the resultant nonenzymatic glycosylation of proteins, and the eventual formation of advanced glycosylation end products in long-lived structural proteins. To investigate the ralationship between the glomerular basement membrane (GBM) changes of diabetic nephropathy and the formation of advanced glycosylation end products, we studied control rats, diabetic rats, and control and diabetic rats who received aminoguanidine, a compound that pharmacologically inhibits formation of advanced glycosylation end products. After 9 months, rat weight was smaller and kidney weight larger in both diabetic groups compared with both control groups. GBM width was increased in the diabetic group compared with the control group. Aminoguanidine administration to diabetic rats ameliorated this increase in GBM. Thus, aminoguanidine administration from the onset of experimental diabetes prevented the widening of the GBM that is typical of diabetes.

Twenty percent of patients with juvenil diabetes mellitus (JDM)

Will develop renal failure within 30 years. The interval between the first clinical signs of nephropathy and terminal renal failure averages 3 years. To find early predictors of diabetic nephropathy, renal functional studies are being carried out in the 250 children followed in the diabetic section of this hospital. Glomerular filtration rate (GFR) and the clearance of Beta-2-microglobulin and albumin are determined. Results are presently available from BO children and show that GFR is increased already shortly after the onset of JDM (149 ±20 ml/1.73 m2/min as compared to 110±12 in controls). GFR remains on a high level during the first 10 years after the onset. 10-15 years after the onset, GFR is no longer sign. different from that in controls. 15 years after the onset, subnormal GFR values are recorded in some patients. 0-2 years after the onset there is a positive correlation between GFR on one hand and average blood sugar and HbA1C on the other hand. 2-6 years after the onset there is no correlation between GFR and HbA1C. 6-10 years after the onset there is a negative correlation between GFR and HbA1C. Fractional excretion of Beta-2-microglobulin is normal in all patients suggesting that the changes in diabetic nephropathy are primarily glomerular. The different correlations between GFR and metabolic control recorded early after the onset and during the later course of the disease suggest that the changes in GFR in JDM are due both to functional adaptation to the altered metabolism and to progressive structural changes.

The development, enhancement, and reversal of the secondary complications of diabetes mellitus

Diabetic glomerulopathy continues as a major problem in the management of the patient with diabetes mellitus; however, evidence in man and in animals underlines the fact that good control of diabetes favorably alters the course of this complication. Islet transplantation in the diabetic rat returns plasma glucose and insulin levels to normal. In parallel mesangial matrix thickening, mesangial deposition of immunoglobulin and urinary excretion of albumin markedly improve following islet transplantation. Although amelioration of diabetes affects the course of glomerulopathy, other factors (most notably measures that increase glomerular capillary pressure) enhance the development of the diabetic renal lesions. Following uninephrectomy or clipping of a renal artery, the remaining (in the case of uninephrectomy) or unclipped diabetic kidney develops the morphologic and functional changes of diabetic nephropathy at a rate greater than in kidneys in an intact diabetic rat. The clipped kidney demonstrates diminished diabetic changes, suggesting a protective effect with decreased glomerular capillary pressure. In addition to measures improving the control of diabetes, procedures reducing factors accelerating diabetic complications may improve the prognosis in diabetic glomerulopathy.

Diabetes Mellitus with Immune Complex Glomerulonephritis

The present study describes 3 patients with the simultaneous occurrence of diabetic nephropathy and immune-complex mediated glomerulonephritis. Renal manifestation included proteinuria and hematuria which were preceded by or co-existent with an infectious process. Renal manifestation included proteinuria and hematuria which were preceded by or co-existent with an infectious process. Renal histology showed the characteristic change of diabetic nephropathy along with those of immune complex glomerulonephritis. Immunofluorescence studies showed a linear pattern with a superimposed granular pattern of IgG and C3 deposits. Renal function and urinary findings improved in the 2 patients who were followed up.

Differential renal protein clearance in diabetes.

Measurements of differential renal protein clearance (ratio of the renal clearance of immunoglobulin-G to that of transferrin) have been performed in long-standing diabetics with varying amounts of proteinuria. In seventy-one diabetics the IgC-transferrin clearance ratio (0.44 ± 0.04, mean ± S.E.M.) was significantly lower than in seventeen normal subjects (1.85 ± 0.24). The mean IgG-transferrin clearance ratio was significantly lower in fourteen of these diabetics with normal amounts of proteinuria than in normal subjects. A further decrease in clearance ratio was apparent when nonproteinuric (125 mg./24 hr.) and minimally proteinuric (500 mg./24 hr.) diabetics were compared. Deterioration of renal function in proteinuric diabetics was associated with an increase in the IgG-transferrin clearance ratio. The results taken overall suggest that an initial fall and a delayed rise in the clearance ratio occurs in individuals who progress to terminal renal failure. The initial fall in the IgG-transferrin clearance ratio may reflect the earliest renal changes of diabetic nephropathy. The relationship of this fall to the onset of carbohydrate intolerance remains to be clarified.

Retinal vascular patterns. IV. Diabetic retinopathy.

It is generally held that microaneurysms constitute the characteristic lesion of diabetic retinopathy. First observed by MacKenzie and Nettleship in 1879, 1 the microaneurysms were rediscovered by Ballantyne and Loewenstein in 1943 2 and have been described by numerous clinicians and pathologists since that time. Noteworthy has been the predominant localization of the diabetic microaneurysms in the central and paracentral regions, their random distribution, and their association with punctate hemorrhages and exudates in the deep retina. It has also been assumed that the microaneurysms and other evidence of angiopathy in diabetic retinas have a bearing on the glomerular changes in diabetic nephropathy 3-5 and that a clarification of the one might yield useful information for the other. As must be evident from the many reviews which have appeared in recent years, 6-12 the pathogenesis of retinal microaneurysms has been a subject of wide speculation based on some firm evidence but