Glomerular heparan sulfate alterations: mechanisms and relevance for proteinuria

Heparan sulfate (HS) is the anionic polysaccharide side chain of HS proteoglycans (HSPGs) present in basement membranes, in extracellular matrix, and on cell surfaces. Recently, agrin was identified as a major HSPG present in the glomerular basement membrane (GBM). An increased permeability of the GBM for proteins after digestion of HS by heparitinase or after antibody binding to HS demonstrated the importance of HS for the permselective properties of the GBM. With recently developed antibodies directed against the GBM HSPG (agrin) core protein and the HS side chain, we demonstrated a decrease in HS staining in the GBM in different human proteinuric glomerulopathies, such as systemic lupus erythematosus (SLE), minimal change disease, membranous glomerulonephritis, and diabetic nephropathy, whereas the staining of the agrin core protein remained unaltered. This suggested changes in the HS side chains of HSPG in proteinuric glomerular diseases. To gain more insight into the mechanisms responsible for this observation, we studied GBM HS(PG) expression in experimental models of proteinuria. Similar HS changes were found in murine lupus nephritis, adriamycin nephropathy, and active Heymann nephritis. In these models, an inverse correlation was found between HS staining in the GBM and proteinuria. From these investigations, four new and different mechanisms have emerged. First, in lupus nephritis, HS was found to be masked by nucleosomes complexed to antinuclear autoantibodies. This masking was due to the binding of cationic moieties on the N-terminal parts of the core histones to anionic determinants in HS. Second, in adriamycin nephropathy, glomerular HS was depolymerized by reactive oxygen species (ROS), mainly hydroxyl radicals, which could be prevented by scavengers both in vitro (exposure of HS to ROS) and in vivo. Third, in vivo renal perfusion of purified elastase led to a decrease of HS in the GBM caused by proteolytic cleavage of the agrin core protein near the attachment sites of HS by the HS-bound enzyme. Fourth, in streptozotocin-induced diabetic nephropathy and during culture of glomerular cells under high glucose conditions, evidence was obtained that hyperglycemia led to a down-regulation of HS synthesis, accompanied by a reduction in the degree of HS sulfation.     

Expression of glomerular heparan sulphate domains in murine and human lupus nephritis.

BACKGROUND: Recently, we identified specific N- and 6-O-sulphated heparan sulphate (HS) domains on activated glomerular endothelial cells. In this study, we evaluated in lupus nephritis the expression of different HS domains on glomerular endothelium and in the glomerular basement membrane (GBM). METHODS: The expression of specific glomerular HS domains and the presence of immunoglobulins (Ig) were determined by immunofluorescence staining of kidney sections of patients with nephritis due to systemic lupus erythematosus (SLE) and MRL/lpr lupus mice. The expression/presence of glomerular HS domains and Ig was also evaluated after eluting Ig from renal sections of lupus mice using two elution methods, and in renal sections of lupus mice treated with heparinoids. RESULTS: Both MRL/lpr mice and patients with lupus nephritis showed a decreased expression of HS in the GBM. The expression of N- and 6-O-sulphated HS domains on glomerular endothelium was decreased in MRL/lpr mice, but increased in SLE patients. MRL/lpr mice had more extensive glomerular Ig deposits than SLE patients. After elution of Ig, the glomerular endothelial expression of N- and 6-O-sulphated HS domains in MRL/lpr mice was recovered and even increased above normal levels, while the expression of HS in the GBM was restored to normal levels. Treatment with heparinoids prevented Ig deposition and preserved the expression of glomerular HS domains at normal levels in lupus mice. CONCLUSION: The expression of specific HS domains on glomerular endothelium and in the GBM is changed during lupus nephritis due to masking by Ig deposits and induction of inflammatory N- and 6-O-sulphated HS domains.     

Fibrillary and immunotactoid glomerulonephritis: Distinct entities with different clinical and pathologic features

BACKGROUND: Controversy surrounds the relatedness of fibrillary glomerulonephritis (FGN) and immunotactoid glomerulonephritis (IT). METHODS: To better define their clinicopathologic features and outcome, we report the largest single center series of 67 cases biopsied from 1980 to 2001, including 61 FGN and 6 IT. FGN was defined by glomerular immune deposition of Congo red-negative randomly oriented fibrils of < 30 nm (mean, 20.1 +/- 0.4 nm). IT was defined by glomerular deposition of hollow, stacked microtubules of > or = 30 nm (mean, 38.2 +/- 5.7 nm). RESULTS: FGN comprised 0.6% of total native kidney biopsies and IT was tenfold more rare (0.06%). Deposits in FGN were immunoglobulin G (IgG) dominant and polyclonal in 96%. IgG subtype analysis in 19 FGN cases showed monotypic deposits in four (two IgG1 and two IgG4) and oligotypic deposits in 15 (all combined IgG1 and IgG4). In IT, deposits were IgG dominant in 83% and monoclonal in 67% (three IgG1 kappa and one IgG1 lambda). FGN patients were a mean age of 57 years, 92% were Caucasian, and 39% were male. At biopsy, FGN patients had the following clinical characteristics (mean, range): creatinine 3.1 mg/dL (0.5 to 14), proteinuria 6.5 g/day (0.8 to 25), 60% microhematuria, and 59% hypertension. Histologic patterns of FGN were diverse, including diffuse proliferative glomerulonephritis (DPGN) (nine cases), membranoproliferative glomerulonephritis (MPGN) (27 cases), mesangial proliferative/sclerosing (MES) (13), membranous glomerulonephritis (MGN) (four), and diffuse sclerosing (DS) (eight). The more proliferative (MPGN and DPGN) and sclerosing (DS) forms presented with a higher creatinine and greater proteinuria compared to MES and MGN. Median time to end-stage renal disease (ESRD) was 24.4 months for FGN and mean time to ESRD varied by histologic subtype: DS 7 months, DPGN 20 months, MPGN 44 months, compared to MES 80 months and MGN 87 months. There was no statistically significant effect of immunosuppressive therapy (given to 36% of FGN patients). By Cox regression (hazard ratio, confidence interval, P value), independent predictors of progression to ESRD were creatinine at biopsy [2.05 (1.55 to 2.72) P < 0.001] and severity of interstitial fibrosis [2.01 (1.05 to 3.85) P = 0.034]. Although IT had similar presentation, histologic patterns, and outcome compared to FGN, it had a greater association with monoclonal gammopathy (P = 0.014), underlying lymphoproliferative disease (P = 0.020), and hypocomplementemia (P = 0.032). CONCLUSION: FGN is an idiopathic condition characterized by polyclonal immune deposits with restricted gamma isotypes. Most patients present with significant renal insufficiency and have a poor outcome despite immunosuppressive therapy, and outcome correlates with histologic subtype. By contrast, IT often contains monoclonal IgG deposits and has a significant association with underlying dysproteinemia and hypocomplementemia. Differentiation of FGN from the much more rare entity IT appears justified on immunopathologic, ultrastructural, and clinical grounds.     

Renal glomerular alterations in patients with cancer: a clinical and immunohistochemical autopsy study

Background: Membranous glomerulonephritis (MGN) can be found in patients with cancer as a paraneoplastic syndrome or it could be manifested clinically before tumor detection. The aim of this study was to evaluate the frequency and type of renal histopathological alterations in patients with malignancy that died without cancer treatment and were submitted to necropsy. Methods: Patient's demographical and clinical data collection and laboratory tests (serum creatinine and urine sample) were evaluated. Results: Kidney fragments from 21 patients were obtained and studied by light microscopy after habitual staining. Immunohistochemistry studies were performed with monoclonal immunoglobulin and tumor markers. Patients' mean age was 71 years and 62% were male. The most frequent tumor was gastric cancer (five cases), followed by colon and oral cavity (three cases each). In 67% of the cases, malignancy was the main cause of death. Serum creatinine was increased in 10 cases, proteinuria in 15, and hematuria was present in 8 cases. The most usual glomerular lesion found was thickening of basement membrane (BM) of the capillary loops. There were two cases of IgA nephropathy, three cases of focal segmental glomerulosclerosis, and one case of MGN. Only in the patient with MGN and metastatic melanoma specific tumor markers were identified in the kidney. Conclusions: We observed a wide range of glomerular pathological changes and abnormal urinary sediments in almost all patients, but we found tumor marker deposits only in the patient with MGN.     

Asymptomatic haematuria and proteinuria: Renal pathology and clinical outcome in 54 children

In a mass screening programme, 54 children with haematuria and proteinuria were detected and evaluated by clinical findings and renal histology. IgA glomerulonephritis (GN) occurred in 29 patients, diffuse mesangial proliferative GN (DPGN) in 16, membranous GN (MGN) in 4, membranoproliferative GN (MPGN) in 3, and focal segmental glomerular sclerosis (FSGS) was seen in 2. Of the 35 children with proteinuria less than or equal to 1 g/m² per day, 21 with IgA GN and 14 with DPGN had only mild to moderate glomerular changes. None of these children had developed renal impairment after a mean period of 6.5 years (range 5–10 years). On the other hand, 8 children with IgA GN, 2 with DPGN, 4 with MGN, 3 with MPGN, and 2 with FSGS had proteinuria that exceeded 1 g/m² per day. The biopsy specimens from these children showed moderate to severe glomerular changes, and 7 of these children had hypertension or renal impairment during the period of evaluation. This study suggests that a poor outcome correlates with the level of proteinuria and the severity of renal pathology in children with haematuria and proteinuria.     

The evolution of membranous glomerulonephritis reconsidered: new insights from a study on relapsing disease

Membranous glomerulonephritis (MGN) has a highly variable clinical course. The morphological basis for this variability has not been fully elucidated. We studied 10 patients with relapsing MGN and compared the findings with those in other clinical courses. The mean duration of follow-up was 10.4 years. Clinical remission occurred, on average, 1.5 years and relapse, on average, 5.6 years after onset. Thirty-one renal biopsies obtained at various clinical phases were studied, 22 of them electron microscopically. The ultrastructural and clinical alterations paralleled each other closely. Subepithelial electron-dense deposits were present during the primary nephrotic phase, were replaced by intramembranous lucent deposits during remission, and reappeared again during relapse. Light microscopic changes (projections, thickening) of the glomerular capillary basement membrane (GBM) were variable. Both ultrastructural and light microscopic changes were unreliable indicators of the duration of illness. A comparative analysis of the present and previous findings suggests that the length of time during which new deposit material is formed determines the evolution of the membranous lesion and the corresponding clinical course. Thus, a short duration results in a single generation of deposits, a morphologically and clinically healing course, and no thickening of the GBM. A repeated formation of deposit material results in a new generation of subepithelial deposits, and a relapsing course. A prolonged formation results in a continuous presence of subepithelial deposits, a thickening of the GBM, and a protracted or progressive course. The morphologic staging currently in use pertains to one particular evolution and course of MGN and therefore should not be used.     

Immunofluorescence on pronase-digested paraffin sections: a valuable salvage technique for renal biopsies

Direct immunofluorescence (IF) on frozen tissue is the method of choice for the study of medical renal diseases. When no glomeruli are available, IF can be performed on the formalin-fixed paraffin-embedded tissue allocated for light microscopy after antigen retrieval with proteases. In this study, the results of IF on frozen tissue (IF-F) and on deparaffinized, pronase-treated tissue (IF-P) were compared in 71 renal biopsies representing 12 major renal diseases. Using IF-P, diagnostic findings were obtained in 100% of cases of lupus nephritis, acute post-infectious glomerulonephritis, cryoglobulinemic glomerulonephritis, fibrillary glomerulonephritis, primary amyloidosis, myeloma cast nephropathy, and light-chain Fanconi syndrome (LCFS), 88% of cases of immunoglobulin (Ig)A nephropathy, 80% of cases of light-chain deposition disease, 60% of cases of membranoproliferative glomerulonephritis type 1, 50% of cases of idiopathic membranous glomerulopathy (MGN) and 20% of cases of anti-glomerular basement membrane (GBM) disease. IF-P was less sensitive than IF-F for the detection of C3 in all disease categories and for the detection of IgG in cases of MGN and anti-GBM disease. The diagnostic kappa light-chain staining was demonstrated in 100% of cases of LCFS by IF-P versus 40% by IF-F. We conclude that IF-P is a valuable salvage immunohistochemical technique for renal biopsies lacking adequate cortical sampling for IF-F, and is superior to IF-F for the diagnosis of LCFS.     

The pathology and clinical features of early recurrent membranous glomerulonephritis

We assessed the earliest manifestations of recurrent membranous glomerulonephritis (MGN) in renal allografts. Clinical, laboratory and pathologic data were reviewed in 21 patients at the initial biopsy within 4 months post-transplant with evidence of MGN and on follow-up biopsies, compared to a biopsy control group of eight transplants without recurrent MGN. The mean time of first biopsy with pathologic changes was 2.7 months. In each earliest biopsy, immunofluorescence (IF) showed granular glomerular basement membrane (GBM) staining for C4d, IgG, kappa and lambda. IF for C3 was negative or showed trace staining in 16/21. On each MGN biopsy positive by IF, 14/19 showed absence of deposits or rare tiny subepithelial deposits by electron microscopy (EM). At the earliest biopsy, the mean proteinuria was 1.1 g/day; 16 patients had <1 g/day proteinuria. Follow-up was available in all patients (mean 35 months posttransplant). A total of 13 patients developed >1 g/day proteinuria; 12 were treated with: rituximab (n = 8), ACEI and increased prednisone dose (n = 2), ACEI or ARB only (n = 2). All patients showed reduction in proteinuria after treatment. A total of 11/16 patients showed progression of disease by EM on follow-up biopsy. Recognition of early allograft biopsy features aids in diagnosis of recurrent MGN before patients develop significant proteinuria.     

The expression of cytoskeletal proteins (α-SMA,vimentin, desmin) in kidney tissue: A comparison of fetal,normal kidneys,and glomerulonephritis

Background: The aim of the study is a comparison of the expression of cytoskeletal proteins, alpha smooth muscle actin (-SMA), vimentin, and desmin in fetal, normal kidney and proliferative (diffuse proliferative and membranoproliferative glomerulonephritis) and nonproliferative (membranous glomerulonephritis) glomerulonephritis.Methods: We have studied the expression of cytoskeletal proteins (-SMA, vimentin, desmin) in the paraffin embedded tissue sections from the kidneys of 10 normal kidney (adults and infants), 13 fetal kidney, 12 membranous glomerulonephritis (MGN), 8 membranoproliferative glomerulonephritis (MPGN), 8 diffuse proliferative glomerulonephritis (DPGN). Interstitial and glomerular positive stainings were evaluated.Results: Vimentin expression was similar in normal infant and adult kidneys with positive staining in glomeruli and negative staining in interstitium. In fetal kidneys, glomerular mesangial and epithelial cells and blastematous areas showed positive reactivity with vimentin. -SMA staining was different among the groups. In fetal kidney, -SMA expression was found in glomerular mesangial cells and blastematous areas. -SMAstaining was positive in peritubular area and glomerular mesangial cells in infant kidney. In adult kidneys, glomerular staining with -SMA disappeared but peritubular positivity continued. Interstitial staining with -SMA was positive in fibrotic areas of proliferative (MPGN, DPGN) and non-proliferative (MGN) glomerulonephritis, but positive glomerular staining with -SMA was found only proliferative glomerulonephritis. Desmin expression was negative in all groups.Conclusions: Desmin is not expressed in early stages of kidney growth, infant and adult kidneys, and proliferative and nonproliferative glomerulonephritis. Interstitial staining of vimentin in the diseased kidney tissues revealed increased fibrosis. -SMA revealed important differences in different stages of nephrogenesis. Glomerular mesangial staining with -SMA in developing (fetal and infant kidneys) and proliferative glomerulonephritis suggest that it may be a marker of proliferation. In addition, it shows myofibroblastic differentiation in interstitium in diseased kidneys.     

Membranous glomerulonephritis with crescents

Purpose

The coexistence of membranous glomerulonephritis (MGN) and necrotizing and crescentic glomerulonephritis (NCGN) is an unusual finding in a renal biopsy except in lupus nephritis. Little is known about whether these lesions are causally related in any clinical setting.

Methods

We reviewed the pathology, presentation, and clinical course of 13 non-lupus patients with combined MGN and NCGN in native kidney biopsies (nine females, four males; median age 69 years), with particular attention to evidence of secondary MGN. Additional IgG subclass and phospholipase A2 receptor (PLA2R) immunofluorescence studies were conducted in seven cases.

Results

Eight biopsies were pauci-immune other than the capillary wall deposits of MGN; one patient had a non-lupus immune complex disease, and four had mesangial deposits, including one with rare subendothelial deposits. None had anti-glomerular basement membrane disease. IgG4 was dominant or codominant in the capillary wall deposits in three cases and virtually absent in four; PLA2R was positive in two cases, and negative in five. Seven patients were judged to have secondary MGN, including five of eight ANCA+ patients. Twelve patients were treated with combinations of steroids, cyclophosphamide, rituximab, followed by durable response in seven and relentless progression to end stage renal disease in four.

Conclusions

Secondary MGN occurs with higher frequency in ANCA-positive NCGN than in the general MGN population. A causal relationship between MGN and NCGN was not established in any patient, but circumstances suggest a common cause in several, including immune complex disease, drug reaction and paraneoplastic syndrome.     

Monocyte infiltration in human glomerulonephritis: alpha-1-antitrypsin as a marker for mononuclear phagocytes in renal biopsies

Alpha-1-antitrypsin detected by immunoperoxidase has been used as a marker for infiltrating monocytes on formalin-fixed, paraffin-embedded sections of 75 renal biopsies. Patients were classified on the basis of glomerular hypercellularity on light microscopy. Monocytes increased with increasing glomerular hypercellularity, most being in diffuse proliferative GN (DPGN) and severe mesangiocapillary GN (MCGN-S). Monocytes were reduced by 48-95% in repeat biopsies of DPGN, mesangial proliferative GN and focal GN, but not in MCGN. In electron micrographs (70 biopsies) monocytes were identified but less frequently than by alpha-1-antitrypsin. Highest numbers were found with subepithelial or subendothelial deposits and lowest numbers in biopsies without deposits. The results show monocytes are detectable in human proliferative GN, numbers increasing with increasing glomerular hypercellularity, and subendothelial and subepithelial deposits.     

Abnormalities of glomerular basement membrane in acute postinfectious glomerulonephritis

The segmental abnormalities of glomerular basement membrane (GBM) were studied by electron microscopy in 69 renal biopsies with acute postinfectious glomerulonephritis (APGN) and correlated with the general morphologic features and clinical findings. Thirty-six were children and 33 were adults. Biopsies were grouped into three stages by light microscopy: exudative stage (25 patients), exudative-proliferative stage (26) and proliferative stage (18). Subepithelial deposits or "humps" were present in 59 patients (86%). The frequency of humps was significantly lower at the proliferative stage than that noted in the earlier biopsies (p less than 0.01). Intramembranous, subendothelial and mesangial deposits were shown in 83% to 88% of the patients. The overall frequency of GBM abnormalities was 45%, showing significantly higher frequency in children than in adults (p less than 0.01). Dissolving subepithelial deposits were often present in the foci with GBM abnormalities. The GBM lesions were not related to more severe clinical manifestations or outcomes, but tended to occur more frequently in later biopsies (p less than 0.01). These results suggest that abnormalities of GBM in APGN are more often present than formerly assumed, especially in children, and could be a normal response to subepithelial deposits. The occurrence of these lesions in other types of immune-related glomerulonephritis may be considered along the same lines.     

Patterns of IgG subclass deposits in membranous glomerulonephritis in renal allografts

Background

Membranous glomerulonephritis (MGN) may develop in the renal allograft either de novo or as a recurrence. These 2 forms of MGN may have different pathogenic mechanisms, with different IgG subclass profiles in the immune deposits. This study examined IgG subclass distributions in recurrent and de novo MGN in allograft kidneys.

Methods

We identified allograft kidneys with MGN, including 7 with recurrent MGN, 2 with de novo MGN, and 2 atypical/indeterminate, and determined the relative intensity of IgG1, IgG2, IgG3, and IgG4 staining in capillary wall deposits by immunofluorescence microscopy.

Results

IgG4 was the dominant or codominant IgG subclass in capillary loop deposits in all 7 cases of recurrent MGN. IgG1 staining was dominant in 3 of 4 de novo or atypical MGN cases and codominant with IgG4 in the fourth.

Conclusions

Although pretransplantation kidney biopsies were not available for comparisons, these findings suggest that all allograft recurrences represent idiopathic MGN and that de novo MGN cases had a different pathogenic mechanism.     

Cationic dextran induces mesangioproliferative nephritis in rats independent of glomerular IgA deposition

Background. Dextran-induced mesangioproliferative glomerulonephritis in mice and, as recently reported, in rats is used as a model of IgA nephropathy. The pathogenetic role of the glomerular IgA deposits in this model, however, is unclear since IgG is often deposited in parallel. Methods. Lewis rats were immunized with cationic DEAE-dextran. Following this, rats received 5 x /week i.v. injections of 3 mg DEAE-dextran each, from days 20 to 80 and were then followed until day 120. Results. Rats developed transient proteinuria (range 63-152 mg/24 h) and haematuria on day 80. Renal biopsies obtained at days 60, 80, 100 and 120 showed mild to severe mesangioproliferative changes at days 80 and 100 which did not persist at day 120. Electron-microscopy revealed mesangial immune deposits, signs of endothelial activation and vacuoles in mesangial cells and podocytes. Compared to normal, age-matched controls, in the nephritic rats significant (P<0.05) increases were noted for glomerular total celluarity, &agr;-smooth-muscle actin expression (a marker of activated mesangial cells), monocyte/macrophage counts, and matrix proteins. Using three different antibodies, no evidence of glomerular IgA deposition was detected at any timepoint. In contrast, glomerular IgG, IgM, C3 and occasional small C5b-9 deposits were present in nephritic rats. Circulating IgG but not IgA anti-dextran antibodies could be demonstrated in nephritic rats. Conclusions. The data confirm that mesangioproliferative glomerulonephritis can be induced in rats by immunization and chronic challenge with cationic dextran. Our data also show that in rats glomerular IgG deposition rather than IgA, appears to play an important pathogenetic role in this mesangioproliferative glomerulonephritis model.     

Membranous glomerulonephritis in renal transplant. A case report and review of the literature

A patient with membranous glomerulonephritis (MGN) presented with recurrent disease after renal transplantation. The disease on the original and the transplanted kidney was characterized by diffuse subepithelial electron-dense deposits on the glomerular basement membranes. Including this case, 23 cases of MGN have been reported in renal transplants, of which 8 are 'recurrent' and 15 are 'de novo'. This incidence of 'de novo' MGN makes it the most common type of 'de novo' glomerulonephritis in renal transplants. Survey of clinical and morphological features of the cases of both the 'de novo' and the 'recurrent' disease failed to identify a specific cause of the MGN. Hypothetically, immunosuppression in transplanted patients may lower the antibody response to levels that favor the development of membranous glomerulonephritis.     

Urotensin-II immunoreactivity in children with chronic glomerulonephritis

BACKGROUND: Human urotensin-II (hU-II) is one of the most potent vasoconstrictors in mammals. To our knowledge, there is no study about the role of U-II in childhood glomerulonephritis.We first determined the expression of h U-II in kidneys of children with chronic glomerular diseases. METHODS: Normal human kidneys were obtained from postmortem biopsies and compared with the kidney biopsy specimens of 24 children with membranoproliferative glomerulonephritis (MPGN) and 6 children with membranous GN. Kidney needle biopsies in 10% neutral buffered-formalin prior to routine processing through to embedded blocking sections were cut, and immunohistochemical reactions were performed on paraffin-embedded tissue by an avidin-biotin peroxidase complex method. The antibodies used in the present study were hU-II. The positivities were revealed as weak (+), moderate (++), and severe (+++), according to the color intensity. RESULTS: In kidneys of children with MPGN, differently fom the normal kidneys, more dense U-II immunoreactivity was seen in the glomerular basement membrane (GBM), glomerular mesangium, Bowman capsule, and tubules. Interestingly, we also observed U-II immunoreactivity in crescents. In children with MGN, U-II was mostly seen in GBM and Bowman capsule. CONCLUSION: Our findings suggest that U-II may have a possible autocrine/paracrine function in the kidneys, and may be an important target molecule in studying renal pathophysiology.     

Immunohistochemical staining of renal biopsy samples in patients with diabetic nephropathy in non-insulin dependent diabetes mellitus using monoclonal antibody to advanced glycation end products

Summary: Immunohistochemical staining of glomeruli in patients with diabetic nephropathy (DN) in non-insulin dependent diabetes mellitus (NIDDM) using the monoclonal anti-advanced glycation end products (AGE) antibody is described. In order to detect the localization of AGE in human renal tissues, we performed immunohistochemical staining using the monoclonal anti-AGE antibody in the glomeruli of 11 patients with DN and 11 age-matched patients with diffuse mesangial proliferative glomerulonephritis without IgA deposition (DPGN) as controls.
Emergence of AGE in the mesangial area was more marked in the glomeruli of patients with severe mesangial expansion than in those with mild expansion. AGE in the extraglomerular arteriolar walls was also observed. In contrast, there was no positive staining using the same antibody in renal tissue obtained from DPGN.
These data support the concept that deposition and/or formation of AGE in the mesangial area might be associated with the progression of diabetic nephropathy.     

Urotensin-II Immunoreactivity in Children with Chronic Glomerulonephritis

Background. Human urotensin-II (hU-II) is one of the most potent vasoconstrictors in mammals. To our knowledge, there is no study about the role of U-II in childhood glomerulonephritis.We first determined the expression of h U‐II in kidneys of children with chronic glomerular diseases. Methods. Normal human kidneys were obtained from postmortem biopsies and compared with the kidney biopsy specimens of 24 children with membranoproliferative glomerulonephritis (MPGN) and 6 children with membranous GN. Kidney needle biopsies in 10% neutral buffered-formalin prior to routine processing through to embedded blocking sections were cut, and immunohistochemical reactions were performed on parafin-embedded tissue by an avidin-biotin peroxidase complex method. The antibodies used in the present study were hU-II. The positivities were revealed as weak (+), moderate (++), and severe (+++), according to the color intensity. Results. In kidneys of children with MPGN, differently fom the normal kidneys, more dense U-II immunoreactivity was seen in the glomerular basement membrane (GBM), glomerular mesangium, Bowman capsule, and tubules. Interestingly, we also observed U-II immunoreactivity in crescents. In children with MGN, U-II was mostly seen in GBM and Bowman capsule. Conclusion. Our findings suggest that U-II may have a possible autocrine/paracrine function in the kidneys, and may be an important target molecule in studying renal pathophsiology.     

Identification of glomerular immune deposits in cryoglobulinemia glomerulonephritis

To provide further evidence of the nature of intraglomerular immune deposits in essential mixed cryoglobulinemia (EMC), we used two mouse monoclonal antibodies against cross-reactive idiotypes present on monoclonal rheumatoid factors (MoRFs) from patients with type II-EMC. MoAb Cc1 reacted with 9 of 16 circulating IgMk MoRFs tested, and MOAb Lc1 with four of the remaining. Using indirect immunofluorescence and immunoperoxidase techniques, we could identify the same cross-reactive idiotype of the serum MoRF in the renal biopsy specimens from 11 of 13 patients with EMC glomerulonephritis. Kidney specimens from the three patients, whose MoRF was not recognized by MoAbs Cc1 and Lc1, were negative. Two out of 30 control renal biopsies from patients with other forms of glomerulonephritis were shown to contain idiotype (Cc1 and Lc1) positive material. Both patients had serum polyclonal RF which could account for this finding. In conclusion, our results provide direct evidence that serum cryo-MoRF participate in the formation of glomerular immune deposits and, presumably, in the pathogenesis of renal damage in EMC glomerulonephritis.