Katarina Vukojevic1, Fila Raguz2, Marijan Saraga3, Natalija Filipovic4, Ivana Bocina5, Darko Kero6, Merica Glavina Durdov7, Vlatka Martinovic8, Mirna Saraga-Babic9. 1. Department of Anatomy, Histology and Embryology, School of Medicine, University of Split, Split, Croatia; Department of Histology and Embryology, School of Medicine, University of Mostar, Mostar, Bosnia and Herzegovina. Electronic address: katarina.vukojevic@mefst.hr. 2. Department of Histology and Embryology, School of Medicine, University of Mostar, Mostar, Bosnia and Herzegovina. 3. Department of Pediatrics, University Hospital in Split, Split, Croatia. 4. Department of Anatomy, Histology and Embryology, School of Medicine, University of Split, Split, Croatia. 5. Department of Biology, Faculty of Science, University of Split, Split, Croatia. 6. School of Medicine, University of Split, Split, Croatia. 7. Department of Pathology, University Hospital in Split, Split, Croatia. 8. Department of Pediatric Surgery, University Hospital Mostar, Mostar, Bosnia and Herzegovina. 9. Department of Anatomy, Histology and Embryology, School of Medicine, University of Split, Split, Croatia. Electronic address: msb@mefst.hr.
Abstract
BACKGROUND: Podocytes are postmitotic, highly specialized cells which maintain the glomerular filtration barrier (GFB). Their injury is characterized by foot processes effacement and change in protein expression leading to proteinuria and end-stage kidney disease. METHODS: Our study focuses on the morphological and immunohistochemical changes of human podocytes during normal development and postnatal period, compared to congenital nephrotic syndrome of the Finnish type (CNF). Kidney tissues taken from 17 human conceptuses 8th-38th weeks old, two healthy and three CNF kidneys were embedded in paraffin for immunohistochemical or double immunofluorescence methods, or were embedded in resin for electron microscopy. Paraffin sections were stained with markers for proliferation (Ki-67), proteins nephrin and nestin, and alpha-tubulin. Quantification of positive cells were performed using Mann Whitney and Kruskal-Wallis test. RESULTS: Tissue analysis showed that proliferation of podocytes gradually decreased during development and disappeared in postnatal period. Decrease in number of ciliated glomerular cells and visceral podocytes (from 47% to 3%), and parietal epithelial cells (from 32% to 7%) characterized normal development. Nestin and nephrin co-expressed in developing podocytes in different cellular compartments. During development, nephrin expression increased (from 17% to 75%) and postnatally changed its pattern, while nestin positive glomerular cells decreased from 98% to 40%. CNF glomeruli displayed increased number of immature ciliated podocytes (6%) and parietal epithelial cells (9%). CONCLUSION: Changes in cytoplasmic alpha-tubulin expression and reduced nephrin expression (20%) indicating association of incomplete podocyte maturation with failure of GFB function and appearance of prenatal proteinuria in CNF patients.
BACKGROUND: Podocytes are postmitotic, highly specialized cells which maintain the glomerular filtration barrier (GFB). Their injury is characterized by foot processes effacement and change in protein expression leading to proteinuria and end-stage kidney disease. METHODS: Our study focuses on the morphological and immunohistochemical changes of human podocytes during normal development and postnatal period, compared to congenital nephrotic syndrome of the Finnish type (CNF). Kidney tissues taken from 17 human conceptuses 8th-38th weeks old, two healthy and three CNF kidneys were embedded in paraffin for immunohistochemical or double immunofluorescence methods, or were embedded in resin for electron microscopy. Paraffin sections were stained with markers for proliferation (Ki-67), proteins nephrin and nestin, and alpha-tubulin. Quantification of positive cells were performed using Mann Whitney and Kruskal-Wallis test. RESULTS: Tissue analysis showed that proliferation of podocytes gradually decreased during development and disappeared in postnatal period. Decrease in number of ciliated glomerular cells and visceral podocytes (from 47% to 3%), and parietal epithelial cells (from 32% to 7%) characterized normal development. Nestin and nephrin co-expressed in developing podocytes in different cellular compartments. During development, nephrin expression increased (from 17% to 75%) and postnatally changed its pattern, while nestin positive glomerular cells decreased from 98% to 40%. CNF glomeruli displayed increased number of immature ciliated podocytes (6%) and parietal epithelial cells (9%). CONCLUSION: Changes in cytoplasmic alpha-tubulin expression and reduced nephrin expression (20%) indicating association of incomplete podocyte maturation with failure of GFB function and appearance of prenatal proteinuria in CNFpatients.
Authors: Kasi C McPherson; Corbin A Shields; Bibek Poudel; Ashley C Johnson; Lateia Taylor; Cassandra Stubbs; Alyssa Nichols; Denise C Cornelius; Michael R Garrett; Jan M Williams Journal: Am J Physiol Renal Physiol Date: 2020-02-18