Ultrastructural background of albuminuria in rats with passive Heymann nephritis

Arai, Takami; Morimoto, Kengo; Masaoka, Hiroshi; Kaneko, Oriyoshi; Mera, Junichiro; Kojima, Kenichiro; Nagase, Mitsumasa; Kobayashi, Shuzo; Ohtake, Takayasu; Hishida, Akira

doi:10.1093/ndt/12.12.2542

Cited by 7 publications

(8 citation statements)

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“…This indicates that the permeability of the GBM itself was already enhanced in these rats and implies that subepithelial deposit formation per se, with or without complement activation, can perturb the integrity of the glomerular permselective filter in the GBM. The observed reduction in the glomerular anionic sites in the LRE in PHN, with or without complement depletion, supports this suggestion, as proposed in an earlier report [4]. However, as seen in PHN-CVF-rats, the reduction in glomerular anionic sites in itself was not sufficient to lead to significant proteinuria.…”

Section: Discussionsupporting

confidence: 88%

Sequence of events in the glomerular capillary wall at the onset of proteinuria in passive Heymann nephritis

Fujigaki

Batsford²,

Yamashita

et al. 2001

Virchows Archiv

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Proteinuria in passive Heymann nephritis (PHN) results from complement-mediated glomerular injury, since complement depletion with cobra venom factor (CVF) prevents proteinuria. However, there are no comprehensive morphological studies identifying the sites of injury leading to onset of proteinuria. To address this issue, we attempted to locate sites of injury involved in the onset of proteinuria in PHN. PHN was induced in intact Munich-Wistar rats (PHN-rats, examined at days 3, 5, and 7) and in complement-depleted rats (CVF treated, PHN-CVF-rats, examined at days 3 and 5). The distribution of endogenous albumin in the glomerular basement membrane (GBM) was studied in in situ drip-fixed glomeruli using immunogold immunocytochemistry, and glomerular anionic sites were visualized by polyethyleneimine staining. In addition, the ultrastructural localization of an epitope recognized by a proteinuria-inducing monoclonal antibody (called 5-1-6) directed against the slit diaphragm was examined. Significant proteinuria was seen in intact PHN-rats, starting at day 5. The intensity of gold labeling for endogenous albumin was significantly increased at the outermost site of the GBM (GBM interfacing foot process and the filtration slit, designated area O) at day 3 in both PHN-rats and PHN-CVF-rats in comparison to untreated controls. At day 5, labeling for albumin in area O was decreased in PHN-rats, but not in PHN-CVF-rats, where it was then higher; in PHN-rats, some areas between epithelial cells and subepithelial deposits were almost free of albumin labeling at day 7. There was no evidence of epithelial cell detachment in any group at day 5, but on day 7 limited focal detachment was seen exclusively in PHN-rats. In proteinuric rats, amorphous material that stained for albumin could be seen in the urinary space, without any exocytosis of labeling by glomerular epithelial cells. A significant reduction of intensity of staining for anionic sites was seen in parallel in both groups, but only in the regions of the lamina rara externa adjacent to subepithelial deposits. This local loss of charge might contribute to enhanced permeability to albumin in both PHN- and PHN-CVF-rats. Changes in the appearance of the filtration slits and in the density and distribution of antigen recognised by monoclonal antibody 5-1-6 were similar in PHN- and PHN-CVF-rats at day 5. Complement depletion prevented neither the reduction in anionic sites of the GBM nor the changes in the slit diaphragm observed. These data suggest that albumin leakage between the epithelial cell and the GBM (area O) could occur in PHN-rats, perhaps as a result of epithelial foot-process changes. This may be the final link in the chain of events responsible for the onset of proteinuria in PHN.

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Section: Discussionsupporting

confidence: 88%

Sequence of events in the glomerular capillary wall at the onset of proteinuria in passive Heymann nephritis

Fujigaki

Batsford²,

Yamashita

et al. 2001

Virchows Archiv

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“…The deposition of Ab at the base of the GEC and the in situ formation of immune complexes in the GBM has been shown to cause charge and hemodynamic effects capable of causing proteinuria (49). The structural effect on the GBM of enlarging sub-GEC deposits may cause proteinuria (9,50,51). The mechanical effects of these sub-GEC deposits such as retraction of GEC and reduced density of anionic sites in the lamina rara externa may be critical to the development of proteinuria (50).…”

Section: Pvg/c6mentioning

confidence: 99%

“…The structural effect on the GBM of enlarging sub-GEC deposits may cause proteinuria (9,50,51). The mechanical effects of these sub-GEC deposits such as retraction of GEC and reduced density of anionic sites in the lamina rara externa may be critical to the development of proteinuria (50). A number of other local mediators have been postulated to damage GBM and GEC, such as reactive oxygen species (52) and PGs (53).…”

Section: Pvg/c6mentioning

confidence: 99%

Induction of Passive Heymann Nephritis in Complement Component 6-Deficient PVG Rats

Spicer

Tran

Killingsworth

et al. 2007

The Journal of Immunology

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Passive Heymann nephritis (PHN), a model of human membranous nephritis, is induced in susceptible rat strains by injection of heterologous antisera to rat renal tubular Ag extract. PHN is currently considered the archetypal complement-dependent form of nephritis, with the proteinuria resulting from sublytic glomerular epithelial cell injury induced by the complement membrane attack complex (MAC) of C5b-9. This study examined whether C6 and MAC are essential to the development of proteinuria in PHN by comparing the effect of injection of anti-Fx1A antisera into PVG rats deficient in C6 (PVG/C6−) and normal PVG rats (PVG/c). PVG/c and PVG/C6− rats developed similar levels of proteinuria at 3, 7, 14, and 28 days following injection of antisera. Isolated whole glomeruli showed similar deposition of rat Ig and C3 staining in PVG/c and PVG/C6− rats. C9 deposition was abundant in PVG/c but was not detected in PVG/C6− glomeruli, indicating C5b-9/MAC had not formed in PVG/C6− rats. There was also no difference in the glomerular cellular infiltrate of T cells and macrophages nor the size of glomerular basement membrane deposits measured on electron micrographs. To examine whether T cells effect injury, rats were depleted of CD8+ T cells which did not affect proteinuria in the early heterologous phase but prevented the increase in proteinuria associated with the later autologous phase. These studies showed proteinuria in PHN occurs without MAC and that other mechanisms, such as immune complex size, early complement components, CD4+ and CD8+ T cells, disrupt glomerular integrity and lead to proteinuria.

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“…It is well known that treatment with cobra venom factor (CVF), which depletes serum complement, prevents development of proteinuria in PHN. Arai et al [22] demonstrated decreased size of subepithelial deposits and reduced retraction of glomerular epithelial cells in CVFtreated animals in the heterologous phase of PHN. Although the proteinuria was prevented, the density of anionic sites in the GBM, estimated by ruthenium red (RR), was not significantly different in the PHN with or without CVF treatment.…”

Section: Discussionmentioning

confidence: 96%

“…Loss of glomerular anionic sites has been documented in PHN using various cationic probes [1,[21][22][23] . In the study by Arai et al [21] , anionic charge of the GBM in the heterologous phase of PHN was examined by measurements of ruthenium red binding to the GBM.…”

Section: Discussionmentioning

confidence: 99%

Glomerular Charge Barrier and Development of Proteinuria in Passive Heymann Nephritis

Christiansen

Kolmannskog²,

Leh³

et al. 2008

Kidney Blood Press Res

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Background/Aim: Passive Heymann nephritis (PHN) in rats is a commonly used model of membranous glomerulonephritis in man where the cause of proteinuria is not fully resolved. This study was designed to investigate the role of the glomerular charge barrier in development of PHN proteinuria. Methods: We studied female Sprague-Dawley rats (n = 33) at days 0, 2, 5 and 14 after induction of PHN by injection of antiserum against renal tubular epithelial antigens (anti-Fx1A). Measuring clearance of chymotrypsinogen A (Chym, MW 25,000, 21 Å) and similar sized anionic chymotrypsinogen (aChym), together with ⁵¹Cr-EDTA, we hypothesized an increased sieving coefficient (θ) of aChym in the early phase of PHN due to impairment of the glomerular charge barrier. Results: No proteinuria was seen at day 2 (5.8 ± 1.4 mg/ 24 h, p > 0.05), while protein excretion increased to 23.2 ± 2.9 mg/24 h (p < 0.05) at day 5 (84 ± 2% albumin) and further to 544.3 ± 51.1 mg/24 h (p < 0.01) at day 14 (60 ± 1% albumin; p < 0.01, day 5 vs. day 14). θ aChym was similar to control at day 2 (0.49 ± 0.03, p > 0.05), increased at day 5 to 0.62 ± 0.02 (p < 0.01) but decreased at day 14 to 0.39 ± 0.02 (p < 0.01). The sieving coefficient of Chym (θ Chym) was decreased at day 14 (p < 0.05). The ratio of θ aChym to θ Chym was increased at day 5 (p < 0.01) but was elsewhere similar to control. Conclusion: The increased ratio of θ aChym to θ Chym and selective albuminuria at day 5 indicates an initial impairment of the glomerular charge barrier in PHN.

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Ultrastructural background of albuminuria in rats with passive Heymann nephritis

Abstract: Depletion of serum complement decreases subepithelial EDDs as well as the number of sites with decreased anionic charge underlying the EDDs. Thus, the size of subepithelial EDDs plays a pivotal role in the onset of albuminuria.

Cited by 7 publications

References 1 publication

Sequence of events in the glomerular capillary wall at the onset of proteinuria in passive Heymann nephritis

Sequence of events in the glomerular capillary wall at the onset of proteinuria in passive Heymann nephritis

Induction of Passive Heymann Nephritis in Complement Component 6-Deficient PVG Rats

Glomerular Charge Barrier and Development of Proteinuria in Passive Heymann Nephritis

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