Neue Erkenntnisse zur glomerulären Struktur

Zusammenfassung

Während der letzten Jahre hat es bedeutende Forschritte im Verständnis des Aufbaus und der Pathomechanismen des renalen Glomerulus gegeben. In dieser Übersichtsarbeit wird eine Auswahl neuer Aspekte beleuchtet: 1.) Die Funktionsweise der glomerulären Filtrationsbarriere ist bis heute noch nicht gänzlich aufgeklärt, obwohl mittlerweile der anatomische Aufbau auch auf molekularer Ebene gut bekannt ist. 2.) Im Glomerulus vermittelt vascular endothelial growth factor (VEGF) ein von den Podozyten ausgehendes, räumliches Signal, das entscheidend den Aufbau des Glomerulus beeinflusst. 3.) Die Theorie des subpodocyte space liefert eine neue Erklärung für den effektiven Rücktransport von VEGF gegen den Filtrationsstrom von den Podozyten zu den Endothelzellen. 4.) Neu entwickelte transgene Mausmodelle haben nach den Podozyten nun auch die Parietalzellen einer systematischen funktionellen Erforschung zugänglich gemacht. Parietalzellen stellen möglicherweise eine intrarenale Progenitorzellpopulation für die Regeneration von Podozyten dar. 5.) Parietalzellen spielen eine bislang unterschätzte Rolle bei verschiedenen glomerulären Erkrankungen. So werden zelluläre Halbmonde im Rahmen einer rapid progressiven Glomerulonephritis vor allem von glomerulären Parietalzellen ausgebildet.

Abstract

In recent years, significant progress has been made in understanding the structure and pathomechanisms of the glomerulus of the kidney. Some of these more recent advances and open questions are discussed in this review: 1.) The functioning of the glomerular filter still remains incompletely understood, although the microanatomy and molecular biology of the glomerular filter has been investigated in great detail. 2.) Vascular endothelial growth factor (VEGF) has been shown to mediate spacial clues that are essential for the polarized distribution of the cells within the glomerulus. 3.) A novel theory of the subpodocyte space offers a novel explanation for the flux of VEGF from the podocytes against the bulk flow of the filtrate to the glomerular endothelial cells. 4.) Novel transgenic mouse models have enabled us to investigate the functional role not only of podocytes but more recently also of parietal cells which might serve as an intrarenal progenitor cell population. 5.) Parietal cells play a so far under-recognized role in various glomerular diseases. In rapid progressive glomerulonephritis, cellular crescents originate predominantly from parietal cells.

Schlüsselwörter

Glomerulus - Filtrationsbarriere - VEGF - Parietalzellen - Podozyten

Keywords

glomerulus - filtration barrier - VEGF - parietal cells - podocytes

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