Glomerular Capillary Basement Membrane Thickening Research Articles

Effect of the oral iron chelator deferiprone in diabetic nephropathy rats.

The aim of the present study was to investigate the effects of the iron chelator deferiprone in diabetic nephropathy (DN) rats and the mechanisms involved. Thirty-two male Wistar rats (180-220 g, 6 weeks old) were randomly divided into a control group, a DN group and two DN groups treated with either 50 or 100 mg/kg per day deferiprone. The DN group was established by feeding of a high-carbohydrate-fat diet and injection of 35 mg/kg streptozotocin into the vena caudalis. The duration of deferiprone treatment was 20 weeks. Histopathological changes were detected by hematoxylin-eosin and Masson staining, as well as transmission electron microscopy. Levels of nuclear factor (NF)-κB, monocyte chemotactic protein (MCP)-1, matrix metalloproteinase (MMP)-9, tissue-specific inhibitor of metalloproteinase (TIMP)-1, cyclo-oxygenase (COX)-2, and nitrotyrosine were determined in kidney tissues using reverse transcription-polymerase chain reaction (RT-PCR), western blotting, and immunohistochemistry. Histopathological observations showed that deferiprone treatment alleviated inflammation infiltrates and collagenous fibrosis in DN rats. Results from RT-PCR and western blotting indicated that deferiprone inhibited the expression of NF-κB, MCP-1, COX-2, and nitrotyrosine, which were overexpressed in DN rats. Immunohistochemistry showed that the mechanism of deferiprone action may involve regulation of MMP-9 and TIMP-1. Decreased MMP-9 expression and increased TIMP-1 expression in DN rats were significantly promoted and inhibited by deferiprone, respectively. Iron chelation by oral deferiprone has a renoprotective effect in DN rats by relieving oxidative stress, inflammation, and fibrosis, which is related to the cytokines NF-κB, MCP-1, MMP-9, TIMP-1, COX-2, and nitrotyrosine.

Long-term streptozotocin-induced diabetes in rats leads to severe damage of brain blood vessels and neurons via enhanced oxidative stress

The aim of this study was to investigate pathophysiological alterations and oxidative stress in various stages of streptozotocin (STZ)‑induced diabetes mellitus (DM) in rats. Male Sprague-Dawley rats (120) were randomized into DM and control groups. Body mass, plasma glucose, glycated hemoglobin (HbA1c), superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) levels, as well as aldose reductase (AR) activities, in brain tissue and serum were determined. Electron microscopy was used to observe neuron and vessel changes in the brain. In STZ‑treated rats, blood glucose, low density lipoproteins, triglycerides and total cholesterol levels increased 1.43‑3.0‑fold and high density lipoprotein, HbA1c and insulin sensitivity index increased 1.1‑1.23‑fold compared with control. At week 16 following treatment, DM rat serum H2O2 concentration was increased, indicating oxidative stress and mRNA levels of GPx and SOD were 2‑fold higher than the control. Protein GPx and SOD levels were reduced (P<0.01). DM rats were identified to exhibit early irregular glomerular capillary basement membrane thickening and vacuolization in the mitochondria and epithelial cells. Neuron cells and blood vessels in the DM rat brains became increasingly abnormal over time with altered Golgi bodies, mitochondria and endoplasmic reticulum cisterns, concurrent with SOD inactivation and AR protein accumulation. Disease progression in rats with STZ‑induced DM included brain pathologies with vascular and neuron cell abnormalities, associated with the reduction of SOD, CAT and GPx activities and also AR accumulation.

Altering expression of α3β1 integrin on podocytes of human and rats with diabetes

The adhesion molecule integrin α3β1 is the major receptor of podocyte to the glomerular capillary basement membrane (GBM). Since progressive alteration of the glomerular extracellular matrix (ECM) compartment leading to GBM thickening is common in diabetic nephropathy, we investigated the cellular distribution of α3β1 integrin in podocytes of patients with diabetic nephropathy and streptozotocin-induced diabetic rats, and we evaluated the effects of high glucose on the cultured rat podocytes. Both human and rat kidneys were stained using the immunoelectron microscopy and immunoperoxidase technique with mouse monoclonal antibodies to human integrin α3 subunit. The results showed that both the number of immunogold particles and the staining of integrin α3 subunit on podocytes were weaker in patients with diabetic nephropathy than those of control kidneys. The staining of α3 on podocytes in the poorly-controlled diabetic rats was also weaker after one and three months of hyperglycemia. However, the staining was identical to controls in rats with only one week of hyperglycemia. High glucose (25 mM) but not streptozotocin in vitro suppressed the α3 expression of cultured rat podocytes. Our results demonstrated that the expression of integrin α3β1 on podocytes was suppressed in both human and rats with diabetes, possibly due to the effects of hyperglycemia, and the suppression became more severe with the duration of diabetes.

Basement membrane-specific chondroitin sulfate proteoglycan is abnormally associated with the glomerular capillary basement membrane of diabetic rats.

We have previously reported the production of monoclonal antibodies (MAb) recognizing the core protein of a basement membrane-specific chondroitin sulfate proteoglycan (BM-CSPG). Using immunohistochemical techniques, we have shown that BM-CSPG is present in almost every basement membrane, one exception being the normal glomerular capillary basement membrane (GBM), where it is absent. In the present study of mature kidneys we examined the distribution of BM-CSPG in streptozocin-induced diabetes mellitus in rats. We found BM-CSPG atypically associated with the GBM of diabetic animals as early as 1 month after induction of diabetes mellitus. Immunoelectron microscopy (IEM) of affected capillary loops showed BM-CSPG present in the subendothelial matrix in areas of GBM thickening and absent in areas where the GBM appears to be of normal thickness. Moreover, the association of BM-CSPG with regions of the pericapillary GBM affects the morphology of the capillary endothelial cells within these areas, directly displacing the cell body from the GBM proper and causing loss of fenestrae. These new data on BM-CSPG distribution reflect abnormal glomerular extracellular matrix protein biosynthesis/turnover in diabetes and suggest that BM-CSPG in the GBM might in turn affect normal capillary structure and/or function.

Systematic evaluation of microangiopathy in diabetic Chinese hamsters: I. Morphometric analysis of minimal glomerular basement membrane thickness in 11- to 15- and 19- to 23-month-old Chinese hamsters

Renal glomeruli of 11- to 15- and 19- to 23-month-old nondiabetic (M) and diabetic (XA and AC) genetic sublines of Chinese hamsters were morphometrically analyzed to determine if minimal capillary basement membrane thickening (CBMT) is a microvascular complication in this animal model. Minimal glomerular capillary basement membrane thickness was significantly elevated in the AC diabetic subline (117.2 nm ± 5.0, P < 0.004) compared with the M nondiabetic subline (99.0 nm ± 14.0) in the 11- to 15-month age span. However, in the 19- to 23-month age range, both the XA (140.2 nm ± 20.0, P < 0.02) and AC (140.1 nm ± 12.4, P < 0.04) diabetic sublines displayed significantly greater glomerular capillary basement membrane thickness in comparison with the M nondiabetic subline (119.0 nm ± 13.4). The greatest influence on CBMT in the diabetics was shown to be a combination of the aging process and severity of hyperglycemia. This initial systematic morphometric study has demonstrated that glomerular CBMT is a characteristic microvascular lesion in 11- to 15-month-old diabetic AC and 19- to 23-month-old diabetic XA and AC Chinese hamsters in comparison with age-matched nondiabetics. Furthermore, this investigation suggests that the Chinese hamster appears to be an acceptable model for the study of chronic complications associated with diabetic nephropathy.

Glomerular disease in captive galagos.

A captive colony of galagos that for several years lived under poor housing conditions and suffered a variety of chronic illnesses showed a high incidence of renal glomerular disease. Several patterns of glomerular disease were seen: four types of proliferative lesions included a mild stalk glomerulitis, more severe stalk-lobular proliferative glomerulonephritis, diffuse proliferative glomerulonephritis, diffuse proliferative glomerulonephritis, and diffuse proliferative and sclerotic glomerulonephritis; and a form of glomerular capillary basement membrane thickening. Glomerular localization of immunoglobulin and the third component of complement as well as some unusual ultrastructural observations in diffuse proliferative and sclerotic glomerulonephritis suggest an immunopathogenesis for this disease.

Inhibitory effect of elastase on the glomerular capillary basement membrane thickening of the experimental congenital diabetic mice (N.S.Y. mice).

Elastase is an elastin lytic enzyme that inhibits the deposition of fat on arterial walls and suppresses fat buildup. The changes in the renal glomerular basement membrane were observed over 30days ofelastase administration in N. Y. S. mice (experimental congenital diabetic animals). and the treated group showed a lessening in the thickening of the basement membrane. The thichness of the basement membrane in treated animals was 2158.7 ± 96.2 A against 2743.8 ± 168.6 A in the control. Thus, a significant difference (P < 0.01) resulted between the groups of N. S. Y. mice. and elastase is presumed to act upon the metabolism of the renal glomerular basement membrane in them.

Diabetic glomerulosclerosis without glucose intolerance

The pathophysiology of the microangiopathy of diabetes mellitus is poorly understood, and the relevance of carbohydrate intolerance remains uncertain. Four patients are presented with renal abnormalities suggestive of diffuse diabetic glomerulosclerosis. These patients have no evidence of carbohydrate intolerance by standard clinical technics. A familial incidence of diabetes mellitus and delayed insulin response to an oral glucose load support a classification of prediabetes or suspected diabetes mellitus for these patients. Early intercapillary nodule formation was seen in only two of the four patients. In the absence of this infrequent pathognomonic finding, an alternate approach to the diagnosis of diabetic glomerulosclerosis is suggested. Diffuse glomerular capillary basement membrane thickening, consistently present with diabetic glomerulosclerosis, is demonstrated by measurements utilizing the latex microsphere technic. The mean glomerular capillary basement membrane thickness of these patients was 4,403 Å, compared with the control value of 3,098 Å (P < 0.001). Other pathologic findings suggestive of diabetic nephropathy include efferent arteriolosclerosis and linear immunofluorescence without electron dense deposits or inflammation. Skeletal muscle capillary basement membranes of all four patients also demonstrated significant thickening. The mean value for the patients was 1,510 Å, as compared with a control value of 961 Å (P < 0.001). The importance of this muscle capillary basement membrane thickening to the diagnosis of diabetic microangiopathy is discussed. The pathologic alterations in the renal biopsy specimens and the demonstration of muscle capillary basement membrane thickening strongly suggest that diabetic glomerulosclerosis may occur in the absence of overt clinical carbohydrate intolerance.