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Takuji Naruse - One of the best experts on this subject based on the ideXlab platform.
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A major pathogenic antigen of Heymann Nephritis is present exclusively in the renal proximal tubule brush border—studies with a monoclonal antibody against pronase-digested tubular antigen
Clinical and experimental immunology, 2008Co-Authors: Yoshito Tsukada, Akira Maezawa, Kumeo Ono, Shintarou Yano, Takuji NaruseAbstract:We have isolated a nephritogenic 120-kD antigen from rat renal tubule brush border that induces rat Heymann Nephritis. A MoAb that recognized this antigen reacted exclusively with the brush border on indirect immunofluorescence and immunoelectron microscopy. Rabbit antiserum against this antigen also reacted exclusively with the brush border. With the injection of this antiserum, rabbit IgG became detectable along the glomerular basement membrane (GBM) after 3 days. Our 120-kD antigen was shown to have a close relationship with gp330 based on the following: (i) this antigen can induce active Heymann Nephritis as gp330; (ii) our MoAb reacted with the immune deposits of nephritic kidneys induced not only by the 120-kD antigen but also by gp330, and conversely, rabbit antiserum against gp330 reacted with those induced by the 120-kD antigen as well as gp330; and (iii) by immunoblotting, polyclonal antibodies against the 120-kD antigen reacted with gp330 and polyclonal antibodies against gp330 reacted with the 120-kD antigen. These observations indicate that antigen present exclusively in the brush border can induce active Heymann Nephritis, and the common antigenic determinants shared by brush border and the coated pits of glomerular epithelium may not be a prerequisite to induce Nephritis. A more precise relationship between the 120-kD antigen and reported C14 fusion protein or 40-kD alpha 2MRAP remains to be established.
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The kinetics of the pathogenic pronase-digested renal proximal tubular antigen and antibody in rat active Heymann Nephritis.
Nephron, 1995Co-Authors: Akira Maezawa, Yoshito Tsukada, Shintaro Yano, Takuji NaruseAbstract:We investigated the pathogenesis of active Heymann Nephritis in the rat by conducing immu-nofluorescent and immunoblotting studies of the pathogenic antigen and the autoantibody, and by detecting this
Dontscho Kerjaschki - One of the best experts on this subject based on the ideXlab platform.
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Role of Xanthine Oxidase in Passive Heymann Nephritis in Rats
2013Co-Authors: Wilfried Gwinner, Dontscho Kerjaschki, Jens Plasger, Ralf P. Brandes, Birgit Kubat, Matthias Schulze, Heinz Regele, Christoph J. Olbricht, Karl-martin KochAbstract:Abstract. Passive Heymann Nephritis (PHN) in rats is a model of human membranous nephropathy characterized by formation of subepithelial immune deposits in the glomerular capillary wall and complement activation. Oxygen radicals have been implicated in the subsequent glomerular damage which leads to proteinuria. This study examines the involvement of xanthine oxidase in this process. Xanthine oxidase activity was increased nearly twofold in glomeruli isolated 1 and 12 d after induction of PHN, and this was associated with increased glomerular superoxide anion generation. Analysis of glomerular samples by Northern and Western blotting revealed no quantitative changes in xanthine oxidoreductase expression in PHN, suggesting conversion of xanthine dehydrogenase to the oxidase form as the cause of increased activity. Treatment of rats with tungsten, an inhibitor of xanthine oxidase, befor
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Role of Xanthine Oxidase in Passive Heymann Nephritis in Rats
Journal of the American Society of Nephrology : JASN, 1999Co-Authors: Wilfried Gwinner, Dontscho Kerjaschki, M Schulze, Jens Plasger, Ralf P. Brandes, Birgit Kubat, Heinz Regele, Christoph J. Olbricht, Karl-martin KochAbstract:Passive Heymann Nephritis (PHN) in rats is a model of human membranous nephropathy characterized by formation of subepithelial immune deposits in the glomerular capillary wall and complement activation. Oxygen radicals have been implicated in the subsequent glomerular damage which leads to proteinuria. This study examines the involvement of xanthine oxidase in this process. Xanthine oxidase activity was increased nearly twofold in glomeruli isolated 1 and 12 d after induction of PHN, and this was associated with increased glomerular superoxide anion generation. Analysis of glomerular samples by Northern and Western blotting revealed no quantitative changes in xanthine oxidoreductase expression in PHN, suggesting conversion of xanthine dehydrogenase to the oxidase form as the cause of increased activity. Treatment of rats with tungsten, an inhibitor of xanthine oxidase, before induction of PHN resulted in a marked decrease in glomerular xanthine oxidase activity and superoxide anion generation, and decreased proteinuria by 80% (day 12: 423+/-245 mg/d in PHN versus 78+/-53 mg/d in tungsten-treated PHN animals, P < 0.01). These findings point to a pivotal role of xanthine oxidase in the pathophysiology of PHN and could be of importance in the therapy of human membranous nephropathy.
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Lipoproteins accumulate in immune deposits and are modified by lipid peroxidation in passive Heymann Nephritis.
The American journal of pathology, 1996Co-Authors: Markus Exner, Martin Susani, Joseph L. Witztum, A. Hovorka, Linda K. Curtiss, S. Spitzauer, Dontscho KerjaschkiAbstract:Proteinuria in passive Heymann Nephritis is primarily caused by reactive oxygen species that are produced by glomerular cells. Reactive oxygen species apparently exert their damaging effects on the glomerular filter by lipid peroxidation and subsequent adduct formation on matrix proteins of glomerular basement membranes. This raised the question as to the source of polyunsaturated fatty acids required as substrates for lipid peroxidation. Here we have localized by immunocytochemistry rat apolipoprotein E and apolipoprotein B within subepithelial immune deposits. Moreover, apolipoprotein B extracted from isolated glomeruli of proteinuric passive Heymann Nephritis rats shows degradation and lipid peroxidation adduct formation, similar to apoproteins of oxidized lipoproteins in atherosclerotic lesions. These data provide evidence that lipoproteins accumulate within immune deposits and suggest that their lipids generate lipid-peroxidation-derived reactive compounds.
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megalin gp330 possesses an antigenic epitope capable of inducing passive Heymann Nephritis independent of the nephritogenic epitope in receptor associated protein
Journal of The American Society of Nephrology, 1995Co-Authors: Robert A. Orlando, Dontscho Kerjaschki, Marilyn G. FarquharAbstract:The Heymann Nephritis antigenic complex (HNAC) consists of two glycoproteins, megalin (gp330), and the receptor-associated protein (RAP). HNAC is expressed on the surface of the glomerular epithelium where it plays a primary role in the pathogenesis of Heymann Nephritis (HN). Several models were previously proposed describing how antibody binding epitopes in HNAC may contribute to the initiation and progression of HN. Although these models suggest that nephritogenic epitopes capable of initiating HN are present in both megalin and RAP, the structural relationship between these epitopes has not been established. Previously a nephritogenic epitope was identified and characterized in RAP that initiates immune complex formation in HN. In this report, the immunologic relationship between nephritogenic epitopes in megalin and RAP were examined to determine whether these epitopes are immunologically distinct or antigenically related. To this end, a polyclonal antibody to megalin was generated that does not recognize RAP by immunoblotting or immunoprecipitation and whether this antibody is capable of inducing passive HN was determined. It was found that antimegalin antibodies devoid of RAP cross-reactivity induced the formation of subepithelial immune deposits (passive HN) when injected into rats. Antibodies eluted from glomeruli of the injected rats recognized only megalin by immunoblotting a cortical extract and did not recognize a RAP fusion protein or any other renal protein. In addition, the eluted antibodies immunoprecipitated two proteolytic fragments of megalin (140 and 75 kd) identifying a pathogenic epitope within a smaller fragment of megalin.(ABSTRACT TRUNCATED AT 250 WORDS)
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gp330 and RAP: the Heymann Nephritis antigenic complex.
Annals of the New York Academy of Sciences, 1994Co-Authors: Marilyn G. Farquhar, Dontscho Kerjaschki, Marita Lundstrom, Robert A. OrlandoAbstract:It is apparent that significant progress has been made in the characterization of gp330 in the years that have elapsed since its initial identification as the nephritogenic antigen of Heymann Nephritis. However, there are still many gaps in our knowledge and we do not yet have a full picture of the molecular events leading to the formation of immune deposits in glomerular capillaries. Moreover, we still do not have direct information on the normal function(s) of gp330 and RAP and their trafficking in renal and other epithelia. The availability of the yolk sac and other cell lines that express gp330 and RAP together with the identification of the functional domains of RAP should greatly facilitate experimental studies designed to elucidate these problems. Progress will also be greatly facilitated in the future when the complete amino-acid sequence of gp330 becomes available, making possible further structural studies. It is our hope that new knowledge obtained on the molecular mechanisms of HN will provide insights into the molecular pathogenesis of human membranous nephropathy and will provide a strategy for the design of appropriate treatments to interrupt the process.
Rene Lafreniere - One of the best experts on this subject based on the ideXlab platform.
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Downregulation of a pathogenic autoantibody response by IgM autoantibodies directed against the nephritogenic antigen in slowly progressive Heymann Nephritis
Pathology International, 2006Co-Authors: Arpad Zsigmond Barabas, Chad D. Cole, Arpad D. Barabas, Rene LafreniereAbstract:The purpose of the study was to find out if a new modified vaccination technique would be effective in downregulating immunopathological events during the course of an experimental autoimmune kidney disease (which is morphologically and functionally similar to Heymann Nephritis) called ‘slowly progressive Heymann Nephritis’ (SPHN). We have shown that the pathogenic IgG autoantibody (aab)-induced experimental autoimmune kidney disease process can be downregulated early on as well as during the chronic progressive phase, when rats were restimulated. The IgM aab, resulting from stimulation by immune complexes made up of rat kidney fraction 3 (rKF3) antigen and rat anti-rKF3 IgM antibody in antigen excess (MIC), can greatly diminish pathogenic aab production by removing or blocking nephritogenic antigens. Reduced IgG aab production limits the formation of damaging immune complexes (IC) in the glomeruli and development of proteinuria. At the end of the experiment 60% and 80% of the MIC-treated groups had no pathogenic IgG aab in their circulation, while all the untreated SPHN rats had high levels of IgG aab associated with disease progression manifesting in increased proteinuria and severe immune complex glomeruloNephritis.
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production of Heymann Nephritis by a chemically modified renal antigen
International Journal of Experimental Pathology, 2004Co-Authors: Arpad Zsigmond Barabas, Chad D. Cole, Arpad D. Barabas, Rene LafreniereAbstract:An autoimmune kidney disease morphologically and functionally similar to Heymann Nephritis (HN) was induced in mature male Sprague Dawley rats by repeated weekly IP injections of a chemically modified azo sonicated ultracentrifuged (u/c) rat kidney fraction 3 (rKF3) antigen in an aqueous medium. The experiment was terminated 15 weeks after the first injection of the chemically altered antigen. Serum samples collected and analysed by an indirect fluorescent antibody test on normal rat kidney sections during the course of the experiment showed a gradual rise in circulating pathogenic autoantibodies directed against the proximal tubular brush border regions. Proteinuria was present and significantly increased in the urine of two of eight rats. The arising immune-complex glomeruloNephritis (ICGN) revealed typical HN kidney disease lesions in 70% of the rats in histological, direct fluorescent antibody and electron-microscopical examinations. Control rats injected similarly with the an unmodified version of the same antigen did not develop the HN-characteristic morphological and functional changes. To our knowledge, this is the first time that the autoimmune kidney disease designated as an active HN has been produced by the administration of a chemically altered renal antigen in an aqueous solution and not by the usual presentation of the nephritogenic renal antigen in an adjuvant.
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Production of a new model of slowly progressive Heymann Nephritis.
International Journal of Experimental Pathology, 2003Co-Authors: Arpad Zsigmond Barabas, Chad D. Cole, Arpad D. Barabas, Rene LafreniereAbstract:A slowly progressive autoimmune kidney disease was induced in Sprague Dawley rats by subcutaneous injection of a chemically modified kidney antigen (rKF3), incorporated into Alum and Distemper complex vaccine, followed by subcutaneous injections of an aqueous preparation of the same antigen. Pathogenic autoantibodies developed, which reacted with fixed glomerular nephritogenic antigen. Subsequently, immunopathological events lead to chronic progressive immune complex glomeruloNephritis and proteinuria. The slowly developing disease was morphologically and functionally similar to Heymann Nephritis (HN). The damage observed in the kidneys of experimental animals at 8 weeks and at the end of the experiment was examined by direct fluorescent antibody test, histology and electron microscopy. The changes were similar to the typical lesions found in HN rat kidneys, but less severe. Animals became proteinuric from 17 weeks onward (instead of the usual 4-8 weeks). By the end of the experiment, at 8 months, 100% of the rats were proteinuric. This new experimental model of autoimmune kidney disease, which is not complicated by intraperitoneal deposition and retention of Freund's complete adjuvant and renal tubular antigens, allowed us to investigate the pathogenesis of the disease processes from a different aspect, and promises to be a useful and improved model for the investigation of future treatment options.
Dennis Brown - One of the best experts on this subject based on the ideXlab platform.
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induction of Heymann Nephritis with a gp330 megalin fusion protein
American Journal of Pathology, 1996Co-Authors: Raktima Raychowdhury, Gang Zheng, Dennis Brown, R T MccluskeyAbstract:Abstract There is considerable evidence that glomerular deposits in Heymann Nephritis, a rat model of membranous Nephritis, result from shedding of immune complexes formed on podocytes and that the principal antigen is part of the extracellular domain of a cell surface glycoprotein receptor called gp330 or megalin. It has also been reported that the immunogen that induces Heymann Nephritis is a complex formed between gp330 and the receptor-associated protein RAP. The recent elucidation of the primary structure of gp330 makes it possible to investigate the ability of defined portions of gp330, devoid of RAP, to induce Heymann Nephritis. In the present study we show that a gp330-glutathione-S-transferase fusion protein, containing 137 amino acid residues (1114 to 1250) of the ectodomain, induces active Heymann Nephritis and that heterologous antibodies against this fusion protein produce passive Heymann Nephritis. By immunofluorescence, typical glomerular immunoglobulin deposits were found, but complement components were lacking and the rats did not develop proteinuria. In the active model, we obtained evidence indicating that the deposits contained portions of the ectodomain of gp330, including regions other than those of the fusion protein. Thus, the deposits were stained by polyclonal antibodies to gp330 and to the gp330 fusion protein, as well as by two monoclonal antibodies reactive with portions of the ectodomain of gp330, only one of which reacted with the fusion protein in vitro. Antibodies against the cytoplasmic domain of gp330 did not stain. Furthermore, we found that RAP was able to bind to gp330 in the glomerular deposits but not to the gp330 fusion protein in vitro. The results show that the region of gp330 spanning amino acid residues 1114 to 1250 contains peptides capable of inducing pathogenic antibodies of Heymann Nephritis without a contributory role of RAP.
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Induction of Heymann Nephritis with a gp330/megalin fusion protein
The American journal of pathology, 1996Co-Authors: Raktima Raychowdhury, Gang Zheng, Dennis BrownAbstract:Abstract There is considerable evidence that glomerular deposits in Heymann Nephritis, a rat model of membranous Nephritis, result from shedding of immune complexes formed on podocytes and that the principal antigen is part of the extracellular domain of a cell surface glycoprotein receptor called gp330 or megalin. It has also been reported that the immunogen that induces Heymann Nephritis is a complex formed between gp330 and the receptor-associated protein RAP. The recent elucidation of the primary structure of gp330 makes it possible to investigate the ability of defined portions of gp330, devoid of RAP, to induce Heymann Nephritis. In the present study we show that a gp330-glutathione-S-transferase fusion protein, containing 137 amino acid residues (1114 to 1250) of the ectodomain, induces active Heymann Nephritis and that heterologous antibodies against this fusion protein produce passive Heymann Nephritis. By immunofluorescence, typical glomerular immunoglobulin deposits were found, but complement components were lacking and the rats did not develop proteinuria. In the active model, we obtained evidence indicating that the deposits contained portions of the ectodomain of gp330, including regions other than those of the fusion protein. Thus, the deposits were stained by polyclonal antibodies to gp330 and to the gp330 fusion protein, as well as by two monoclonal antibodies reactive with portions of the ectodomain of gp330, only one of which reacted with the fusion protein in vitro. Antibodies against the cytoplasmic domain of gp330 did not stain. Furthermore, we found that RAP was able to bind to gp330 in the glomerular deposits but not to the gp330 fusion protein in vitro. The results show that the region of gp330 spanning amino acid residues 1114 to 1250 contains peptides capable of inducing pathogenic antibodies of Heymann Nephritis without a contributory role of RAP.
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Detection of two forms of GP330. Their role in Heymann Nephritis.
The American journal of pathology, 1993Co-Authors: D. R. Bachinsky, Gang Zheng, Dennis Brown, John L. Niles, M. Mclaughlin, M. Abbate, G. Andres, Robert T. MccluskeyAbstract:Abstract Heymann Nephritis is characterized by glomerular immune deposits that contain a glycoprotein called gp330. The deposits are believed to result from shedding of immune complexes formed on podocytes. Complexes are also shed from proximal tubule cells, when antibodies combine with gp330 on the cell surface. We performed the present study to investigate what portion of the gp330 molecule is shed, using a rabbit antiserum against a peptide deduced to be in the cytoplasmic domain of gp330, as well as a rabbit antiserum and two monoclonal antibodies that recognize extracellular epitopes of gp330. The anti-cytoplasmic peptide antiserum precipitated from Fx1A (a crude renal cortical membrane preparation), a protein with a mass of about 440 kd that was reactive with two monoclonal anti-gp330 antibodies. (In our experiments, the protein called gp330 generally has a mass estimated to be about 440 kd.) The anti-cytoplasmic peptide antiserum also reacted with a truncated gp330 protein produced in transfected COS cells. Immunohistochemical studies showed that all the antibodies recognized the same group of epithelial cells. However, as seen in immunoultrastructural studies of proximal tubules, the anti-cytoplasmic peptide antiserum reacted only with components at the base of microvilli, whereas the anti-gp330 ectodomain antibodies identified material not only at the base, but over the surface of microvilli as well. In rats with Heymann Nephritis, glomerular deposits and material shed into tubule lumens reacted with antibodies against extracellular epitopes of gp330, but not with the anti-cytoplasmic peptide antiserum. We propose that there are two forms of gp330 on the cell surface of proximal renal tubules. One form is restricted to coated pit regions at the base of microvilli and has a cytoplasmic domain containing a sequence deduced from a partial complementary DNA encoding gp330. The other form is present over microvilli (and possibly at the base of microvilli as well) and lacks the cytoplasmic domain deduced from the complementary DNA. The complexes that are shed in Heymann Nephritis contain either a portion of gp330 cleaved from the full-length molecule or a form of gp330 that lacks the cytoplasmic domain.
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Loss of antigens associated with the apical endocytotic pathway in proximal tubules from rats with Heymann Nephritis.
The American journal of pathology, 1991Co-Authors: E. J. Gutmann, John L. Niles, Robert T. Mccluskey, Dennis BrownAbstract:In addition to the glomerular lesions associated with Heymann Nephritis, a rat model of human membranous Nephritis, proximal tubule damage, and a perturbation of proximal tubule function also have been reported to occur in this disease. The aim of the present study was to examine in more detail the nature of the apical plasma membrane damage in proximal tubules using specific antibodies directed against clathrin, gp330, and a proton-pumping adenosine triphosphatase, all of which are components of the apical endocytotic apparatus of these epithelial cells. Immunocytochemical studies revealed a marked reduction in staining for all three antigens in proximal tubules from rats with active Heymann Nephritis. Furthermore endocytotic uptake of intravenously injected FITC-dextran was considerably lower in diseased animals than in normal rats. Gp330 and rat IgG were identified as components of the luminal debris that accumulated during the course of Heymann Nephritis. These results show that perturbation of proximal tubule endocytosis occurs in Heymann Nephritis together with a loss of three apical antigens that are normally localized on membrane domains associated with the apical endocytotic pathway in these cells. The results also suggest that antibody-antigen complexes may be shed from the plasma membrane in both the glomerulus and the proximal tubule in this disease.
Yoshito Tsukada - One of the best experts on this subject based on the ideXlab platform.
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A major pathogenic antigen of Heymann Nephritis is present exclusively in the renal proximal tubule brush border—studies with a monoclonal antibody against pronase-digested tubular antigen
Clinical and experimental immunology, 2008Co-Authors: Yoshito Tsukada, Akira Maezawa, Kumeo Ono, Shintarou Yano, Takuji NaruseAbstract:We have isolated a nephritogenic 120-kD antigen from rat renal tubule brush border that induces rat Heymann Nephritis. A MoAb that recognized this antigen reacted exclusively with the brush border on indirect immunofluorescence and immunoelectron microscopy. Rabbit antiserum against this antigen also reacted exclusively with the brush border. With the injection of this antiserum, rabbit IgG became detectable along the glomerular basement membrane (GBM) after 3 days. Our 120-kD antigen was shown to have a close relationship with gp330 based on the following: (i) this antigen can induce active Heymann Nephritis as gp330; (ii) our MoAb reacted with the immune deposits of nephritic kidneys induced not only by the 120-kD antigen but also by gp330, and conversely, rabbit antiserum against gp330 reacted with those induced by the 120-kD antigen as well as gp330; and (iii) by immunoblotting, polyclonal antibodies against the 120-kD antigen reacted with gp330 and polyclonal antibodies against gp330 reacted with the 120-kD antigen. These observations indicate that antigen present exclusively in the brush border can induce active Heymann Nephritis, and the common antigenic determinants shared by brush border and the coated pits of glomerular epithelium may not be a prerequisite to induce Nephritis. A more precise relationship between the 120-kD antigen and reported C14 fusion protein or 40-kD alpha 2MRAP remains to be established.
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The kinetics of the pathogenic pronase-digested renal proximal tubular antigen and antibody in rat active Heymann Nephritis.
Nephron, 1995Co-Authors: Akira Maezawa, Yoshito Tsukada, Shintaro Yano, Takuji NaruseAbstract:We investigated the pathogenesis of active Heymann Nephritis in the rat by conducing immu-nofluorescent and immunoblotting studies of the pathogenic antigen and the autoantibody, and by detecting this