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Glomerular fibrillary deposits have occasionally been reported in diabetic nephropathy, but no large-scale, ultrastructural evaluation of these deposits has been reported so far. Here, we report our study of glomerular non-Congophilic, DnaJ homolog subfamily B member 9 negative fibrillary deposits in diabetic nephropathy as characterized by transmission electron microscopy. Clinical data from 55 patients with biopsy-confirmed diabetic nephropathy and 18 healthy living donors were reviewed, and their biopsies were evaluated by light microscopy, immunofluorescence, and electron microscopy. Small fibrillary structures with a diameter of 10 ± 1 nm were present in all cases with diabetic nephropathy, regardless of the histologic class. In addition, glomerular fibrillary structures with a diameter of 23 ± 5 nm or 30 ± 7 nm were present in 35 cases. Interestingly, especially the small- and medium-sized fibrils, usually without apparent organization, were comparable with fibrils in fibrillary glomerulopathy. We conclude that glomerular fibrillary deposits occur far more commonly in renal biopsies of patients with diabetic nephropathy than generally considered. This is an important finding because their similarity to fibrils in fibrillary glomerulonephritis may complicate the histologic diagnostic process, especially in cases of overlapping clinical manifestations. Therefore, when encountering fibrillary deposits on electron microscopy, it is important to consider diabetic nephropathy as an alternative diagnosis., (Copyright © 2024 United States & Canadian Academy of Pathology. Published by Elsevier Inc. All rights reserved.)

Complement factor C4d was recently observed in renal biopsies from patients who had IgA nephropathy and a poor prognosis. We previously reported that C4d is a common denominator in microangiopathies. In this retrospective cohort study, we investigated whether C4d is a marker of microangiopathy in both IgA nephropathy and IgA vasculitis with nephritis, and whether patients with C4d and microangiopathy have poor renal outcome. We examined 128 renal biopsies from adult and pediatric patients, including normotensive and hypertensive patients, who presented with IgA nephropathy or IgA vasculitis with nephritis. Biopsies were re-evaluated in accordance with the Oxford classification, scored for additional lesions, and stained for complement proteins using immunohistochemistry, including C4d and C5b-9. Clinical data were collected with a mean (±SD) follow-up period of 51 ± 39 months. Changes in estimated glomerular filtration rate over time were compared using linear mixed-effects models. Renal survival was analyzed using multivariable Cox regression. Microangiopathic lesions were present in 20% of all biopsies (23% and 9% of patients with IgA nephropathy and IgA vasculitis with nephritis, respectively). Microangiopathy was associated with C4d and C5b-9 deposits, a higher number of chronic lesions, and hypertension (all p < 0.05). Patients with C4d and microangiopathic lesions had significantly poorer renal survival than patients without these findings, corrected for hypertension (p < 0.01). In conclusion, patients with IgA nephropathy or IgA vasculitis with nephritis with a combination of C4d positivity and microangiopathy comprise a clinical subgroup with an increased number of chronic lesions, lower estimated glomerular filtration rate, and poorer renal survival, even when corrected for hypertension. These data suggest that complement activation is involved in the development of microangiopathy in patients with IgA nephropathy and IgA vasculitis with nephritis, and that complement-mediated microangiopathy contributes to disease progression.

Induction of anti-Thy-1 nephritis in different strains of inbred rats results in phenotypically different types of renal diseases. In Wistar and Lewis (LEW) rats, a transient influx of ED1+ macrophages occurs 24 hours after injection of anti-Thy-1 antibodies, whereas this does not occur in F344 rats. The present experiments were designed to investigate the role of the kidney in the regulation of the monocyte influx in this model. To dissociate the role of the immune system from local intrarenal factors in the control of monocyte influx, anti-Thy-1 nephritis was induced in LEW rats with an F344 kidney transplant and in F344 rats with a LEW kidney allograft. Acute rejection episodes were prevented by treatment with an anti-CD4 monoclonal antibody. Control rats received a syngeneic kidney graft. Monocyte influx after injection of anti-Thy-1 antibodies was found in the glomeruli of both LEW and F344 kidneys removed from LEW recipients, whereas there was no demonstrable monocyte influx after infusion of anti-Thy-1 antibodies in either LEW or F344 kidneys removed from F344 recipients. Monocyte infiltration correlated with the subsequent expansion of the mesangial extracellular matrix. The inability to attract monocytes was not due to the lack of glomerular expression of chemokines, because F344 and LEW glomeruli demonstrated a similar expression of monocyte chemoattractant protein-1 (MCP-1). Differences in the ability to activate the complement system were excluded. We conclude that the immune system controls the glomerular influx of monocytes and that the reaction of the mesangial cells is probably controlled by combinations of cytokines produced during the inflammatory process.

The survival rate of hepatocytes after allogeneic hepatocyte transplatation (HTX) is low, possibly because of formation of intravascular hepatocyte aggregates. The aim of this study was to determine the role of integrins in intravascular aggregation and intraparenchymal survival of transplanted hepatocytes in a fully allogeneic rat model. First, the expression profile of various integrins was determined on both isolated hepatocytes in vitro and on hepatocyte aggregates in recipient livers after intraportal transplantation of allogeneic hepatocytes. Next, the role of these integrins in hepatocyte aggregation was determined in an in vitro attachment assay on liver sections with function-blocking anti-integrin monoclonal antibodies (mAb). The results showed that anti-alpha 1 beta 1 integrin mAb significantly block hepatocyte attachment to vessel walls and liver parenchyma in vitro. Subsequently, the effect of preincubation of hepatocytes with anti-integrin mAb on their intravascular aggregation and on intraparenchymal survival was studied in an allogeneic HTX model. Preincubation with anti-leukocyte function-associated antigen-1 alpha or anti-beta 2 mAb significantly intravascular hepatocyte aggregation, and anti-leukocyte function-associated antigen-1 alpha mAb enhanced intraparenchymal survival. Preincubation with anti-alpha 1 or anti-beta 1 mAb did not inhibit aggregation but significantly improved survival from 2% to up to 45% at Day 2 after transplantation (p < 0.001). In conclusion, our results suggest that the blocking of alpha 1 beta 1 integrin significantly improves survival of allotransplanted hepatocytes.

The polycystic kidney disease-1 gene, which is mutated in the majority of patients with autosomal dominant polycystic kidney disease, has been identified. The protein encoded by this gene, polycystin, has no homology with any gene known thus far. To gain more insight into the function of polycystin, we raised antibodies against synthetic peptides and a fusion protein corresponding to the sequence of two different fragments of polycystin. Two of the antibodies were capable of immunoprecipitating an in vitro transcription and translation product corresponding to a fragment of polycystin. In the cyst-lining epithelium of polycystic kidney disease-1 patients, a strong staining was observed. In normal adult and embryonic kidney tissues, expression was seen in the epithelium of all tubular structures and in the glomerular parietal and visceral epithelium (podocytes), although the podocytes were mainly recognized on cryosections and not on paraffin sections. A double-labeled immunofluorescence with one of the polycystin antibodies and the monoclonal antibody 8G8 ascertained that within the glomerular tuft podocytes were recognized.

Background: Hereditary cerebral hemorrhage with amyloidosis (Dutch) (HCHWA-D) and Alzheimer's disease (AD) have certain clinical and histopathologic features in common; both are characterized by cerebral amyloid beta deposits. Extracellular matrix (ECM) components have been demonstrated in plaques and in vascular amyloid of AD, suggesting a causative relation., Experimental Design: We studied the immunohistochemical expression of the ECM components collagen type I, III, and IV, heparan sulfate proteoglycan (HSPG), laminin, and fibronectin in cortical tissue of six HCHWA-D patients, two AD patients, and five controls., Results: The vasculature of control patients and the noncongophilic vessels in HCHWA-D and AD patients stained for all ECM components, with the exception of collagen type I in part of the capillaries. The media of normal larger vessels stained for collagen type I and III and fibronectin; a similar pattern was found in the vascular amyloid in HCHWA-D and AD patients. The plaques in HCHWA-D and AD reacted for HSPG and weakly for collagen III and IV and laminin. Furthermore, with the exception of anti-collagen type I, all anti-ECM Ab decorated coarse deposits clustered in the vicinity of thick-walled, amyloid-laden vessels in HCHWA-D patients; these deposits were not spatially related to amyloid beta-positive plaques., Conclusions: This study demonstrates the presence of ECM components in the main pathologic features of HCHWA-D and as perivascular deposits. The observed distribution of matrix molecules is partly different from AD. The ECM may well be essential for the evolvement of the pathology of HCHWA-D.

Background: We have conducted an immunohistochemical analysis to investigate the presence of cellular adhesion molecules in normal and diseased human kidneys., Experimental Design: A total of 44 renal biopsies were classified in eight groups according to pathologic diagnosis. Using immunohistochemistry, microscopical evaluation by two observers in a blinded fashion, and statistical analysis (p < 0.01), significant changes in the expression of intercellular adhesion molecule-1, vascular cell adhesion molecule-1, and endothelial-leukocyte adhesion molecule-1 were evaluated in diseased versus normal kidneys., Results: Small caliber vessels, such as peritubular and interstitial capillaries remained negative or showed decreased expression of vascular cell adhesion molecule-1. Upregulation of this molecule was seen only on the endothelium of interstitial arterioles and venules of diseased kidneys. Expression of intercellular adhesion molecule-1 was significantly increased on parietal epithelium of glomeruli in membranous nephropathy and Henoch-Schönlein purpura, on mesangium in Henoch-Schönlein purpura, membranoproliferative glomerulonephritis and IgA nephropathy, and in small interstitial vessels in membranous nephropathy and membranoproliferative glomerulonephritis. Interstitial infiltrates contained only few intercellular adhesion molecule-1-positive cells in Henoch-Schönlein purpura and IgA nephropathy. Kidneys with lupus nephritis and Henoch-Schönlein purpura demonstrated an increase of endothelial-leukocyte adhesion molecule-1 on parietal epithelium of glomeruli and on tubular epithelium. In membranoproliferative glomerulonephritis, this increase was seen only on parietal epithelium of glomeruli., Conclusions: These results show for the first time (a) endothelial vascular cell adhesion molecule-1 induction in various glomerulonephritides and (b) endothelial-leukocyte adhesion molecule-1 induction in the kidney. Complementary to earlier in vitro work, our findings indicate that these molecules play distinct roles in the pathogenesis of immune-mediated renal disease.

Background: In murine chronic graft-versus-host disease, an experimental model for lupus nephritis, autoantibodies against renal tubular epithelium can be found. Part of these antibodies are directed against a constituent of renal tubular epithelium, the enzyme Dipeptidyl peptidase IV (DPP IV). DPP IV is present on the cell membrane of glomerular epithelial and endothelial cells, and plays an important role in cell-extracellular matrix interactions. In mice and rats, administration of heterologous anti-DPP IV antibodies can induce proteinuria and podocyte effacement., Experimental Design: In this study, the glomerular DPP IV enzyme activity was investigated in the course of graft-versus-host disease in (C57BL/10 x DBA/2) F1 hybrids both by light- and electron microscopy using a DPP IV-specific substratum., Results: Light microscopical examination revealed an overall reduction of DPP IV activity and an altered distribution pattern in glomeruli as early as 4 weeks after induction of graft-versus-host disease. Immunofluorescence studies using anti-DPP IV antibodies showed actual redistribution, excluding antibody-mediated enzyme inactivation. Enzyme electron microscopy revealed an irregular deposition of reaction product characterized by a patchy, "moth eaten" appearance of the endothelial and epithelial membranes. This process occurred simultaneously with the development of albuminuria and preceded the effacement of epithelial foot processes. In control mice, DPP IV showed a continuous distribution along endothelial and podocyte membranes., Conclusions: In view of these findings we postulate that impairment of the function of DPP IV as a non integrin adhesion molecule may be one of the causative factors underlying the structural and functional lesions observed in this model for lupus nephritis.

Background: Recent data suggest that the extracellular matrix of organs and heterogeneous integrin expression of tumor cells may influence metastasis distribution., Experimental Design: Three human melanoma cell lines were characterized for integrin expression, in vitro binding to cryostat sections of different organs, and ability to generate experimental metastases in triple immunodeficient mice., Results: The three cell lines exhibited heterogeneous expression of integrins, binding to cryostat sections, and organ colonization. A primary melanoma cell line (PM-WK) did not give rise to experimental metastases, showed scant or mild attachment to only a few organ tissue sections, and showed absent or minimal expression of alpha-integrin subunits tested (VLA 1-6) and alpha v beta 3. In contrast, two lymph node derived lines exhibited distinct patterns of organ colonization: MM-RU colonized only the lungs and expressed predominantly alpha 2 beta 1 and alpha v beta 3 integrin, whereas MM-AN colonized lung and extrapulmonary sites including pancreas and subcutaneous brown fat and expressed predominantly alpha 2 beta 1 and alpha 6 beta 1 integrin. In vitro, MM-RU exhibited marked attachment to lung, brown fat, kidney, and adrenal with no binding to liver, pancreas, brain, or muscle tissue sections, whereas MM-AN had a similar binding profile but with additional attachment to liver and pancreas. Function blocking anti-beta 1 monoclonal antibody inhibited the attachment of MM-RU and MM-AN cells to these tissues (p < 0.001), whereas function blocking anti-alpha 5 and an unrelated monoclonal antibody (HLA class I) did not. Function blocking anti-alpha 2 monoclonal antibody inhibited MM-RU cell adhesion (p < 0.001) but not MM-AN adhesion. However, the function blocking monoclonal antibody alpha 6 beta 1 significantly inhibited the binding of MM-AN to these tissues., Conclusions: These data suggest that alpha 2 beta 1 and alpha 6 beta 1 mediate differential melanoma cell attachment to organ tissue sections in vitro and that differences in integrin expression of these melanoma cells may be involved in differential organ colonization in vivo.

Background: We studied the development of glomerulosclerosis in murine chronic graft-versus-host disease, a model for human systemic lupus erythematosus., Experimental Design: The disease was induced in (C57BL10 x DBA/2)F1 hybrids by injection of DBA/2 lymphocytes leading to deposition of auto-antibodies in the glomeruli, and a lupus type of nephritis morphologically. We have determined the levels of mRNA coding for laminin (B1 and B2), a 67 kilodalton laminin binding protein, and types I and IV collagen, in control and graft-versus host disease mice at various times after disease induction., Results: Laminin and collagen mRNAs were increased in whole kidneys 4 weeks after induction of the disease. At week 10, all animals displayed dramatic stimulation of alpha 1(I), alpha 1(IV), laminin B1, and B2 mRNAs. The 67 kilodalton laminin binding protein mRNA was also doubled from week 4 to 16. In isolated glomeruli, the mRNA level coding for laminin B2 was already significantly increased from week 8. This enhancement of laminin synthesis corresponds to the mesangial expansion and to the development of laminin-containing spike formations of the glomerular basement membrane at week 8., Conclusions: The expansion of the mesangial matrix in murine chronic graft-versus-host disease is caused at least in part, by an increased production of extracellular matrix components by glomerular cells. These results demonstrate that the increase of specific extracellular matrix components mRNAs precedes light microscopic changes. Quantitative evaluation of the mRNA levels coding for extracellular matrix proteins may reveal a useful method for the early detection of the development of glomerular sclerosis at the stage preceding the onset of anatomo-clinical changes.

The present studies dealt with the pathogenesis of renal involvement in murine chronic graft-versus-host disease, which is a model for human systemic lupus erythematosus. The disease was induced in (C57BL10xDBA/2)F1 hybrids by injection of DBA/2 lymphocytes. The animals developed systemic disease accompanied by deposition of autoantibodies in the glomeruli and a lupus type of nephritis. Antibodies were eluted from glomeruli isolated during various stages of the disease by magnetic extraction from iron-perfused kidneys. For assessment of the specificity of the antibodies, we used indirect immunofluorescence, an enzyme-linked immunosorbent assay, and immunoblotting. In glomeruli from week 4, autoantibodies were found to be directed against several antigens, among which were the glomerular basement membrane component laminin and the glomerular enzyme dipeptidyl peptidase IV, whereas week 8 glomeruli also showed antibodies directed against nuclear antigens. Both laminin and dipeptidyl peptidase IV are known nephritogenic antigens occurring in renal tubular epithelial brush border preparations. Antibodies eluted from isolated glomeruli of diseased animals bound in a granular pattern along the glomerular capillary wall after in vivo transfer. Anti-renal tubular epithelial antibodies in the sera of diseased animals were affinity purified and injected into naive mice, which induced immune complex glomerulonephritis and proteinuria, thus confirming the nephritogenic role of these autoantibodies in this model.

Antibodies directed against tubular brush border antigens (RTE) are used to induce heterologous immune-complex nephritis. Among these antigens a glycoprotein with a molecular weight of 330 kilodaltons (gp330) has been shown to be of pathogenetic significance. We investigated whether antibodies other than those directed against gp330 are present in anti-RTE and whether they play a pathogenetic role. By using enzyme-linked immunosorbent assay techniques and Western blotting, we investigated polyclonal antibodies directed not only against crude RTE but also against RTEgp, a purified glycoprotein fraction of RTE, with respect to activity against glomerular basement membrane (GBM) components laminin, fibronectin, and type IV collagen. Both antibody preparations showed reactivity predominantly to the 220 kilodaltons subunit of laminin. Lower but nevertheless distinct reactivity to fibronectin and type IV collagen was also found. The antibody fraction directed against components of the GBM, which was isolated from anti-RTE IgG by affinity chromatography, showed linear binding to the GBM in indirect immunofluorescence studies. Injection of these antibodies into the renal artery also led to linear binding to the GBM with linear deposition of complement factors 3 and 9 and induced a weak and transient proteinuria. Immunoelectron microscopy revealed binding of the antibodies to glomerular epithelial and endothelial cell surfaces adjacent to the GBM. Injection of anti-RTE antibody absorbed to GBM components resulted in binding of antibodies and complement factors 3 and 9 in a fine granular pattern along the GBM, whereas injection of unabsorbed anti-RTE led to a course granular pattern. We conclude that the presence of antibodies (cross-)reacting with laminin, fibronectin, and type IV collagen in anti-RTE antibody has pathogenetic effects and could explain differences in pathogenicity between monospecific anti-gp330 antibody and polyclonal anti-RTE antibody.