Analysis of intra-GBM microstructures in a SLE case with glomerulopathy associated with podocytic infolding.
BACKGROUND
Systemically podocytic infolding into the GBM which causes nonargyrophilic holes in the GBM in association with intra-GBM microstructures has been considered as a new pathological entity. However, its pathomechanisms are largely unknown.


METHODS
We analyzed intra-GBM microstructures in an SLE patient with glomerulopathy associated with podocytic infolding by immunoelectron microscopy for vimentin (a marker for both podocyte and endothelium) and C5b-9 and by 3D reconstruction of transmission electron microscopy (TEM) images by computer tomography method.


RESULTS
Immunofluorescent study showed immunoglobulin deposition in a diffuse, capillary pattern; however, electron-dense deposits like stage 3 membranous nephropathy could be found only in some capillary loops by TEM in spite of the systemic existence of podocytic infolding and the intra-GBM microstructures. Three-dimensional reconstructed images of the TEM images revealed that some of the intra-GBM microstructures made connections with the podocyte. The clustered microstructures underneath the podocyte and their surroundings looked as a whole like the degraded part of podocyte in 3D reconstructed images. Immunoelectron microscopy showed that vimentin was positive in most intra-GBM microstructures. C5b-9 was positive along the entire epithelial side of the GBM and in some microstructures, suggesting that the podocytes may be attacked by C5b-9 and that the microstructures may contain C5b-9 bound cellular membranes.


CONCLUSIONS
Intra-GBM microstructures may be originated mainly from the podocyte. Podotyte and GBM injuries caused by C5b-9 attack to podocytes might contribute in part to podocytic infolding and intra-GBM microstructures in this case.
Fujigaki
Yoshihide
Y
The First Department of Medicine, Hamamatsu University School of Medicine, Hamamatsu, 431-3192, Japan. yf0516@hama-med.ac.jp
Muranaka
Yoshinori
Y
Sakakima
Masanori
M
Ohta
Isao
I
Sakao
Yukitoshi
Y
Fujikura
Tomoyuki
T
Sun
Yuan
Y
Katafuchi
Ritsuko
R
Joh
Kensuke
K
Hishida
Akira
A
D000328:Adult; D015938:Complement Membrane Attack Complex / Q000032:analysis; D005260:Female; D050533:Glomerular Basement Membrane / Q000473:pathology* / Q000648:ultrastructure; D006801:Humans; D007091:Image Processing, Computer-Assisted; D021621:Imaging, Three-Dimensional; D007150:Immunohistochemistry; D008180:Lupus Erythematosus, Systemic / Q000378:metabolism / Q000473:pathology*; D016253:Microscopy, Immunoelectron; D050199:Podocytes / Q000473:pathology* / Q000648:ultrastructure; D014746:Vimentin / Q000032:analysis
D015938:Complement Membrane Attack Complex; D014746:Vimentin