ECM Characterization Reveals a Massive Activation of Acute Phase Response during FSGS.

Eva Nora Bukosza,Helga Schachner,Gabor Szénási,Sigurd Krieger,Katharina Nöbauer,Christoph Aufricht,Christoph Kornauth,André Oszwald,Ebrahim Razzazi Fazeli,Klaus Kratochwill,Peter Hamar,Nicole Huttary,Karin Hummel,Christoph A Gebeshuber

doi:10.3390/ijms21062095

Abstract

The glomerular basement membrane (GBM) and extra-cellular matrix (ECM) are essential to maintain a functional interaction between the glomerular podocytes and the fenestrated endothelial cells in the formation of the slit diaphragm for the filtration of blood. Dysregulation of ECM homeostasis can cause Focal segmental glomerulosclerosis (FSGS). Despite this central role, alterations in ECM composition during FSGS have not been analyzed in detail yet. Here, we characterized the ECM proteome changes in miR-193a-overexpressing mice, which suffer from FSGS due to suppression of Wilms’ tumor 1 (WT1). By mass spectrometry we identified a massive activation of the acute phase response, especially the complement and fibrinogen pathways. Several protease inhibitors (ITIH1, SERPINA1, SERPINA3) were also strongly increased. Complementary analysis of RNA expression data from both miR-193a mice and human FSGS patients identified additional candidate genes also mainly involved in the acute phase response. In total, we identified more than 60 dysregulated, ECM-associated genes with potential relevance for FSGS progression. Our comprehensive analysis of a murine FSGS model and translational comparison with human data offers novel targets for FSGS therapy.

Highlights

The kidney glomerulus is essential for the filtration of blood
Manual curation revealed 111 bona fide extra-cellular matrix (ECM)-associated proteins according to the matrisome resource database [15] plus additional proteins not primarily associated with ECM (Table S2)
We found strong and significant expression changes for 18 up- and two downregulated proteins in ECM isolates in miR-193a Focal segmental glomerulosclerosis (FSGS) mice, four proteins were even exclusively detected in FSGS (Table 1.)

Summary

Introduction

A sieve-like structure is formed by interdigitating foot processes of podocytes and underlying fenestrated endothelial cells. Those cellular components are separated by the glomerular basement membrane/extra-cellular matrix (GBM/ECM). Dysregulation of ECM deposition and formation of excessive connective tissue histologically manifests as sclerosis and can cause organ dysfunction or failure [4], especially in glomerular diseases [5,6,7]. Heterogeneous underlying causes (e.g., gene mutations, circulating factors, miRNAs, hypertension, drugs, viruses) invariably lead to the common ultrastructural denominator—podocyte foot process effacement—or podocyte loss, which clinically manifests as nephrotic range proteinuria. FSGS frequently progresses to a common diagnostic endpoint defined by pronounced sclerotic lesions causing loss of glomerular function and end-stage renal disease (ESRD) [8,9]. The elucidation of changes in the ECM composition during FSGS progression might be instrumental to gain a better understanding of these pathological processes and aid development of novel therapies

Methods

Results

Conclusion