Focal glomerular sclerosis in the fawn-hooded rat.

We have examined the nature of focal glomerular sclerosis (FGS) in fawn-hooded (FH) rats. The fawn-hooded rat develops pathologic features similar to those observed in steroid-resistant focal glomerular sclerosis, ie, by light microscopy some of the glomeruli appear normal but others show areas of solidification confined to one or two lobules of the tuft. The pathogenesis of this disease is not well known and there is a great need for an animal model. In the FH animal, a marked difference in the development of the lesion was noted between male and female rats. Fifty percent of 4-month-old males had proteinuria in excess of 10 mg/day (none of the females had significant proteinuria), while all 12-month-old males had proteinuria in excess of 45 mg/day (female 12-month-old FH rats had mean proteinuria of 7 mg/day). At 6 months of age continuing through 12 months of age, male FH rats had mesangial deposits of IgG, IgM, and, occasionally, C3, demonstrable by immunofluorescence, whether or not FGS was present. Subepithelial electron-dense deposits were never seen by electron microscopy either at 6 of 12 months. Six-month-old animals frequently did not exhibit FGS. Instead, the glomerular epithelial cells, exhibited fusion of foot processes, vacuolization, and, in some areas, focal loss of the epithelial covering on the glomerular basement membrane (GBM). Six-month-old males with proteinuria exhibited focal loss of negative charge from all layers of the filtration barrier. The GBM from sclerotic glomeruli of 12-month-old rats was commonly denuded of epithelium. None of the animals in this study was uremic. FH rats demonstrated FGS associated with progressive glomerular epithelial cell injury.     

Focal and segmental glomerular hyalinosis and sclerosis in the rat.

A glomerular disease spontaneously developing in Wistar rats was studied by light and electron microscopy and by immunofluorescence techniques. The disease is characterized by the local subendothelial deposition of hyaline material leading to increase of mesangial matrix and the development of adhesions. Immunofluorescence shows deposition of complement and IgM and to a lesser degree also of IgG in these lesions. There is a constant relationship of these early changes with the vascular pole of the glomerulus. It is confirmed that female rats are resistent to the disease as are male rats fed a sodium-deficient diet. A higher protein excretion was found in normally fed male rats as compared to female rats and to rats on a sodium-deficient diet. These differences already existed before the normally fed male rats developed glomerular disease. From these studies it is suggested that an appropriate name for this disease would be focal and segmental glomerular hyalinosis and sclerosis and that hemodynamic factors could be an important etiologic mechanism. The histopathology of the disease bears a striking resemblance to focal sclerosing glomerulopathy with segmental hyalinosis sometimes found in kidneys of patients with an idiopathic nephrotic syndrome.     

Focal segmental glomerular hyalinosis and/or sclerosis in rats with congenital unilateral hydronephrosis.

Focal segmental glomerular hyalinosis and/or sclerosis (FSHS) was observed in five Wistar-Imamichi rats with congenital unilateral hydronephrosis (CUH rats). Marked proteinuria (164.9 +/- 138.4 mg/day) was observed in the CUH rats. Immunoperoxidase staining for IgM, C3 and IgG was positive in the glomeruli, showing in a focal, segmental pattern that corresponded to the areas of FSHS seen by light microscopy. These glomerular findings were extremely similar to those of human focal glomerular sclerosis (FGS). FSHS was found to be common to both the hydronephrotic kidney and the contralateral kidney without hydronephrosis. Morphometry revealed that the glomerular area of the juxtamedullary glomeruli was greater than that of superficial glomeruli in control rats (11,037 micron2 vs. 6,847 microns2). On the other hand, glomerular hypertrophy was observed in non-sclerotic glomeruli of CUH rats (superficial glomeruli; 12,477-16,123 microns2, juxtamedullary glomeruli; 14,635-18,418 microns2). Also, a decreased in the number of glomeruli within the range 1.8-4.1 per unit area (1 mm2) was seen in CUH rats compared with control rats (mean 4.4). These results suggest that the increased rate of development of FSHS is based on hyperfiltration in the remaining functional nephrons.     

Collagen VII expression in glomerular sclerosis.

Glomerular sclerosis is the final stage of a variety of kidney diseases and matrix molecules not normally expressed in the extracellular matrix are synthesized and accumulate during the sclerotic process. Collagen type VII is the major component of the anchoring fibrils at the dermal-epidermal junction, but it is usually not present in normal glomeruli. The aim of this study was to investigate whether this type of fibrillary collagen, different from types I and III, is expressed in chronically diseased glomerular extracellular matrix. The presence and distribution of collagen VII have been examined in 50 renal biopsies by indirect immunofluorescence staining, standard electron microscopy, and immuno-electron microscopy. In selected cases, collagen VII mRNA expression was also measured by RT-PCR on isolated glomeruli. Cases included focal segmental glomerulosclerosis, minimal change disease, membranous glomerulonephritis, IgA nephropathy, SLE nephritis, diabetic glomerulosclerosis, ischaemic renal disease, extracapillary glomerulonephritis, and end-stage renal disease. Collagen VII protein and mRNA expression was absent or present in trace amounts in normal kidneys or in disorders with only a mild increase of mesangial matrix, without scarring of the tuft. Maximal expression was evident in the presence of adhesions between the glomerular tuft and Bowman's capsule or fibrous crescents. The results showed that collagen VII is actively synthesized and laid down in areas of glomerular and/or tubular scarring, irrespective of the underlying disease, confirming the de novo expression of fibrillary collagens in diseased renal extracellular matrix. The appearance of an anchoring collagen may be a response to support mechanical stress and it takes part in the process of cell proliferation and tissue repair.     

Light and electron microscopical studies of focal glomerular sclerosis

Renal biopsy material from seven cases of the nephrotic syndrome due to focal glomerular sclerosis has been studied by light, electron, and immunofluorescent microscopy. The nature of glomerular basement membrane changes and the scar tissue was also studied. It was found that the glomerular basement membrane and mesangial matrix formed the major components of scar tissue. On the basis of a short history in some of our cases, a poor response to steroid therapy in the early stages, and the distinct morphological changes, it is suggested that focal glomerular sclerosis has an independent origin and is not a stage of minimal change lesion.     

Ferritin deposition in the glomerular deposits of focal glomerular sclerosis in the rat

The glomerular lesions of focal sclerosis clinically associated with a steroid-resistant nephrotic syndrome, are of unknown origin. IgM and C3 deposits and electron dense material found in areas of sclerosis are not convincing evidence of an immune pathogenesis. These deposits have been studied in a rat model of focal sclerosis induced by uninephrectomy and repeated aminonucleoside administration. Sclerotic lesions closely resembling human disease developed in the remaining kidney. There was a severe progressive proteinuria. Seventy-eight days after initial aminonucleoside injection 65 per cent of glomeruli were sclerotic with IgM, IgG, C3 and fibrinogen deposits, and electron dense deposits by electron microscopy. To study macromolecule deposition in this model of focal sclerosis, ferritin uptake 4 and 24 h after intravenous ferritin given at 77 days was compared in focal sclerosis rats with control rats without sclerosis (uninephrectomy plus saline-only injections). In focal sclerosis rats sclerotic areas contained massive accumulations of ferritin. In unaffected segments of sclerotic glomeruli, and normal glomeruli of focal sclerosis rats, ferritin concentration was no different from controls. Abnormal ferritin trapping in areas of sclerosis suggests that the presence of IgM and C3 may be due to a similar mechanism, and is not indicative of an immune pathogenesis for focal sclerosis.     

Studies of progressive glomerular sclerosis in the rat.

To obtain a better understanding of the sequential development of sclerosis in immune glomerular disease, the authors induced experimental membranous nephropathy in unilaterally nephrectomized rats and evaluated the lesions that developed over a 35-week period. Serial renal biopsies were examined by light and immunofluorescence microscopy for IgG, C3, neoantigens of the membrane attack complex (MAC), and interstitial (Type III) and basement membrane (Type IV) collagen. Urinary protein excretion increased from 208 +/- 19 mg/day to 308 +/- 36 mg/day during the period of observation. Progressive mesangial sclerosis, crescent formation, and interstitial fibrosis developed in association with deposition of Type IV but not Type III collagen in the glomeruli. Capillary wall deposits of IgG, C3, and MAC gradually decreased, whereas coarse granular deposits of C3 and MAC were visible in sclerotic areas beginning at 8 weeks. The appearance of complement components in early sclerotic lesions raises the possibility that they are of pathogenetic importance. The absence of interstitial collagen in sclerotic glomeruli suggests that the components of the lesion are produced solely by glomerular cells.     

Mesangial lesions and focal glomerular sclerosis in the aging rat.

The pathogenesis of focal glomerular sclerosis (FGS) and its relation to proteinuria and idiopathic nephrotic syndrome are unknown. Urine protein excretion in Sprague-Dawley rats increased with age. Fifty per cent of 12-month and 90 per cent of 24-month-old animals were proteinuric (greater than 20 mg. per day). Heavily proteinuric old rats manifested biochemical changes characteristic of nephrotic syndrome without significant loss of renal function. Three-month, 6-month, and nonproteinuric 12-month-old animals had mesangial deposits of IgM in occasional lobules of some glomeruli and slight mesangial hyperplasia. Four proteinuric 12-month-old rats had diffuse 4+ deposits of IgM in the mesangium of most glomeruli, basement membrane thickening and epithelial cell foot process fusion without FGS. The mesangial IgM deposits eluted in acid buffer and did not fix complement. Six proteinuric 12-month-old rats had focal and segmental areas of glomerular sclerosis with adhesions to Bowman's capsule, foamy cells, intraluminal eosinophilic deposits and capillary wall wrinkling and collapse. These lesions were more advanced in 24-month-old animals. Nonproteinuric 24-month-old rats did not have detectable FGS. Mesangial uptake of colloidal carbon was normal in proteinuric and nonproteinuric animals without FGS. Mesangial uptake of colloidal carbon was normal in proteinuric and nonproteinuric animals without FGS and reduced in proteinuric animals with FGS. In the aging rat the development of proteinuria and mesangial IgM deposition apparently precede development of a focal sclerotic glomerular lesion with histologic and ultrastructural features similar to FGS in man. The generalized impairment of mesangial phagocytic function in proteinuric rats with FGS suggests that this lesion may result from mesangial overload and dysfunction consequent to the persistent increase in glomerular permeability and proteinuria.     

Increased glomerular Bax/Bcl2 ratio is positively correlated with glomerular sclerosis in lupus nephritis

Introduction

The role of intrinsic pathway of apoptosis in pathogenesis of lupus nephritis (LN) is still not clear. We investigated the relation between the expression of two major proteins of the intrinsic pathway of apoptosis; bcl2 as an antiapoptotic protein and bax as a proapoptotic one; in renal tissue of LN.

Effect of hyperlipidemia on glomerular sclerosis in unilateral nephrectomized rats

The development of focal segmental glomerular sclerosis (FSGS) and its relation to hypertriglycemia were studied in unilateral nephrectomized rats. Group A (n = 6), fed standard rat chow supplemented with 20% beef tallow and 0.6% cholic acid for 25 weeks, showed evidence of hypertriglycemia (109.4 +/- 4.3 mg/dl). Group B (n = 7) was given the same rat chow as group A, but they did not have high serum levels of TG (66.4 +/- 2.3 mg/dl). Group C (n = 6) were the controls and their serum TG levels were 53.0 +/- 3.8 mg/dl. The incidence of FSGS and body weight was significantly higher in group A than in groups B (p less than 0.01) and C (p less than 0.05). In all three groups, rats with over a 4% FSGS revealed significantly high serum TG levels, proteinuria, and body weight, as compared with rats with less than 1% of FSGS. The serum cholesterol levels did not correlate with the incidence of FSGS. We tentatively conclude that hypertriglycemia induced by a diet rich in saturated fatty acid may play an important role in the production and progression of FSGS.     

Participation of macrophages in segmental endocapillary proliferation preceding focal glomerular sclerosis

We studied infiltrating cells in the glomeruli of eight cases with focal segmental endocapillary proliferation (FSEP) using monoclonal antibodies to leukocyte common antigen, T cells, B cells, and monocytes/macrophages (Mo/Mφ). It was demonstrated by sequential biopsies performed in five cases that FSEP preceded focal glomerular sclerosis (FGS). Cell types in FSEP were compared with those in FGS from 17 patients with persistent nephrotic syndrome, ten non-nephrotic patients, and eight patients with nephrotic syndrome which was initially responsive to steroid therapy but relapsed, as well as minimal change specimens from nine nephrotic patients. In the glomeruli, the mean total leukocyte counts increased significantly in the FSEP group (P < 0.01). The serial sections in FSEP revealed that Mo/Mφ were the predominant cells and were localized in areas of endocapillary proliferation. T-cell or B-cell infiltration was less marked. The extensive intracapillary distribution of p150,95 antigen belonging to the integrin family and acting as a C3bi receptor suggested that FSEP may be mediated by adhesion molecules expressed on Mo/Mφ. These findings indicate that Mo/Mφ may play a key role in FGS which shows endocapillary proliferation in the initial stage.     

Decreased T-colony formation by lymphocytes from patients with focal glomerular sclerosis

The T-colony-forming capacity was examined in 13 normal subjects and 8 patients with biopsy-proven focal glomerular sclerosis (FGS). Fifteen patients with chronic mesangial proliferative glomerulonephritis (CGN) without renal insufficiency were studied as a disease control. The two main assays used were the counting of T colonies formed by the patients' lymphocytes, and the measurement of T-colony-forming activity in conditioned medium from cultures of patients' lymphocytes. The levels of T-colony-forming cells (TCFC) and T-colony-stimulating factor (TCSF) were decreased in patients with FGS compared with those in normal controls and lower in FGS patients with the nephrotic syndrome (NS) than in those without NS. In contrast, these parameters in CGN patients with or without NS did not differ from normal subjects. TCSF activity for TCFC in both normal individuals and FGS patients was removed from media conditioned by phytohemagglutinin (PHA)-stimulated peripheral blood lymphocytes (PHA-LCM) with interleukin-2 (IL-2) receptor bearing cultured T cells. These in vitro findings suggest that IL-2 is the essential factor contained in PHA-LCM. Thus, depressed TCFC in FGS patients with NS may result in part from impaired generation of TCSF by lymphocytes.     

人肾小球系膜细胞增生硬化相关新基因AngRem104的表达和功能研究

目的:AngRem104(angiotensinⅡrelatedgenesinmesangialcells)是血管紧张素Ⅱ(AngⅡ)刺激系膜细胞后上调表达的新基因(GenBank登录号是AF367870)。本研究旨在进一步探讨新基因AngRem104的功能, 为研究肾小球增生硬化可能的分子机制奠定基础。方法:用Northernblot检测AngRem104在正常人组织中的表达分布及其在AngⅡ刺激和刺激被losartan阻断后的表达变化。构建AngRem104与pcDNA3.1/V5/His-TOPO的正义和反义真核表达载体, 并转染至体外培养人肾小球系膜细胞, 用RT-PCR的方法检测在AngRem104基因过度表达时纤粘连蛋白(FN)的表达变化。通过ExPASy对AngRem104进行生物信息学分析。结果:生物信息学分析提示AngRem104是一种核蛋白。Northernblot结果显示AngRem104在正常人心脏、胎盘、肝脏、骨骼肌、肾脏和胰腺组织中广泛的表达, 而在脑组织和肺中未检测到表达。在AngⅡ刺激人系膜细胞后6h, AngRem104表达明显上调, 并可持续至48h, 但却剂量依赖地被AngⅡI型受体(AT1R)拮抗剂(losartan)抑制。用RT-PCR的方法检测到在AngRem104基因过度表达时FN的表达明显上调, 而当反义阻断AngRem104基因的表达时, 在AngⅡ刺激下人系膜细胞FN的表达无明显改变。结论:AngRem104是在正常人组织内广泛表达的核蛋白。血管紧张素Ⅱ可特异性调节AngRem104的表达, 而AngRem104可调控AngⅡ诱导的FN的上调表达。     

Morphometric analysis of the glomerular capillary area--a comparison of minimal change nephrotic syndrome, focal glomerular sclerosis, and pre-eclampsia.

A morphometric analysis was performed to compare the capillary area in non-sclerotic glomeruli in focal glomerular sclerosis (FGS), pre-eclampsia with focal sclerotic change of the glomeruli, and minimal change nephrotic syndrome (MCNS). The mean and standard deviation of the capillary area was greater in FGS than in pre-eclampsia and MCNS. Tubulo-interstitial lesions, such as tubular atrophy, interstitial fibrosis, and lymphocytic infiltration, were more severe in FGS than in pre-eclampsia. The presence of tubulo-interstitial changes including tubular atrophy and interstitial fibrosis with lymphocytic infiltration is thought to be an important prognostic factor in pre-eclampsia as well as in FGS. Unequal dilatation of the glomerular capillaries in non-sclerotic glomeruli may be harmful to the glomeruli and may lead to the development of glomerular sclerosis.     

罗格列酮对2型糖尿病大鼠血浆resistin的影响及对肾小球硬化的干预研究

目的： 研究罗格列酮对糖尿病大鼠血清巨噬细胞因子resistin水平的影响,探讨该药物对糖尿病肾小球硬化的干预及可能的作用机制。方法： 20只10周龄Wistar大鼠随机分为糖尿病肾病（DN）模型组和罗格列酮干预组(DN+RSG),另取10只Wistar大鼠作为正常对照组(NC)。DN和罗格列酮干预组大鼠右肾切除后经过阴茎背静脉注射35 mg/kg链脲菌素（STZ）,罗格列酮组按照10 mg·kg-1·d-1的剂量给予罗格列酮灌胃,DN组及正常对照组喂饲普通饮食。STZ注射20周后留取静脉血和24h尿,后处死大鼠并取肾组织。ELISA法检测血浆白细胞介素-1(IL-1)、肿瘤坏死因子-α (TNF-α)及resistin水平,免疫比浊法测定高敏C反应蛋白(hs-CRP),并测定24 h尿微量白蛋白、空腹血糖及肾功能水平。光镜下观察肾组织的病理改变情况,免疫组化检测肾小球转化生长因子-β1(TGF-β1) 的表达,Western blotting检测Smad2磷酸化水平。 结果： 与NC组比较,DN组大鼠血浆炎症因子IL-1、TNF-α、hs-CRP及resistin的水平均显著升高;罗格列酮干预后血浆中上述指标含量均显著低于模型组。与DN组比较,罗格列酮干预组的空腹血糖无明显变化,但24 h尿微量白蛋白定量及肾功能水平均明显下降。罗格列酮干预后肾小球内TGF-β1蛋白表达及Smad2磷酸化水平较DN组显著降低,并且其肾小球系膜增生程度也较DN组明显减轻。结论： 罗格列酮具有延缓及改善糖尿病肾小球硬化的作用,该作用可能与其降低resistin及其它炎症相关因子的表达有关。针对炎症有望控制DN的发生发展。     

Participation of macrophages in glomerular sclerosis through the expression and activation of matrix metalloproteinases

In order to investigate the role of macrophages in glomeruli in the progression of glomerular sclerosis, methyl-cellulose (MC) was administered intraperitoneally to Wistar rats, in addition to intravenous injection of anti-thy1-1 antibody. In this group of rats (Thy-1 + MC group), many macrophages infiltrated in the lytic mesangium accompanied by rupture of capillary loops at an early stage and stayed with abundant deposition of mesangial matrices until day 35, whereas the proliferative lesions following mesangiolysis almost vanished in the rats treated with anti-thy1-1 antibody alone (Thy-1 group). In immunostaining, matrix metalloproteinase (MMP)-9 was expressed along regenerating capillaries of the Thy-1 group and in extracapillary lesions of the Thy-1 + MC group after day 7. In gelatin zymography, the gelatinolytic band for MMP-9 was expressed much more strongly in the Thy-1 + MC group than in the Thy-1 group at day 3, but it was expressed a little more strongly in the Thy-1 group than in the Thy-1 + MC group at day 7. The bands for an active form of MMP-2 were more strongly expressed in the Thy-1 + MC group than in the Thy-1 group throughout the experimental period. These results suggest that persistent accumulation of macrophages in mesangium induces glomerular sclerosis through expression and activation of MMP.     

Spontaneous glomerular sclerosis in aging Sprague-Dawley rats. II. Ultrastructural studies.

Increased protein filtration and work overload have been proposed to account for the development of glomerular sclerosis in old rats. Sprague-Dawley rat kidneys were examined ultrastructurally from birth through 24 months of age to further delineate pathogenetic factors. There was progressive thickening of all basement membranes with lamination, intramembranous pseudolinear deposits, and degeneration. The glomerular basement membrane (GBM) was 1300 A at birth and increased to 4800 A by 24 months of age. GBM thickening correlated very closely with age (r = 0.90, P less than 0.001), correlated roughly with mesangial sclerosis, but did not correlate at all with proteinuria. Obliteration of podocytes and degenerative changes in the cytoplasm occurred in all cell types and was present in both proteinuric and nonproteinuric rats. These findings suggest that the lesion of spontaneous glomerular sclerosis of aging rats results not from proteinuria but from the natural process of abiotrophic involution. Further, this lesion is but a more obvious indicator of the alterations occurring simultaneously in other portions of the kidney.     

The wt1-heterozygous mouse; a model to study the development of glomerular sclerosis

In the present study, it is shown that mice heterozygous for wt1 develop glomerular sclerosis and the nature and time course of events leading to the glomerular scarring are determined. Wt1-heterozygous (wt1het) mice and their wild-type littermates were closely monitored from birth and plasma levels of urea, creatinine, and albumin were compared with histological data and clinical features. One of the first indications of nephropathy in the wt1het mouse was the development of proteinuria, accompanied by progressive elevation of the plasma levels of urea and creatinine. Subsequently, the mice developed albuminuria, which correlated with thickening of the glomerular basement membrane and fusion of the podocyte foot processes. Glomerulosclerosis was a relatively late event, accompanied by severe albuminuria and loss of WT1, nephrin, CD2AP, and alpha-actinin-4.     

Afferent arteriolopathy and glomerular collapse but not segmental sclerosis induce tubular atrophy in old spontaneously hypertensive rats

In chronic renal disease, the temporal and spatial relationship between vascular, glomerular and tubular changes is still unclear. Hypertension, an important cause of chronic renal failure, leads to afferent arteriolopathy, segmental glomerulosclerosis and tubular atrophy in the juxtamedullary cortex. We investigated the pathological changes of hypertensive renal disease in aged spontaneously hypertensive rats using a large number of serial sections, where we traced and analyzed afferent arteriole, glomerulus and proximal tubule of single nephrons. Our major finding was that both afferent arteriolopathy and glomerular capillary collapse were linked to tubular atrophy. Only nephrons with glomerular collapse (n = 13) showed tubules with reduced diameter indicating atrophy [21.66 ± 2.56 μm vs. tubules in normotensive Wistar Kyoto rats (WKY) 38.56 ± 0.56 μm, p < 0.05], as well as afferent arteriolar wall hypertrophy (diameter 32.74 ± 4.72 μm vs. afferent arterioles in WKY 19.24 ± 0.98 μm, p < 0.05). Nephrons with segmental sclerosis (n = 10) did not show tubular atrophy and tubular diameters were unchanged (35.60 ± 1.43 μm). Afferent arteriolar diameter negatively correlated with glomerular capillary volume fraction (r = −0.36) and proximal tubular diameter (r = −0.46) implying reduced glomerular and tubular flow. In line with this, chronically damaged tubules showed reduced staining for the ciliary protein inversin indicating changed ciliary signalling due to reduced urinary flow. This is the first morphological study on hypertensive renal disease making correlations between vascular, glomerular and tubular components of individual nephron units. Our data suggest that afferent arteriolopathy leads to glomerular collapse and reduced urinary flow with subsequent tubular atrophy.