Peritoneal Dialysis Fluid Supplementation with Alanyl-Glutamine Attenuates Conventional Dialysis Fluid-Mediated Endothelial Cell Injury by Restoring Perturbed Cytoprotective Responses.

Rebecca Herzog,Seth L Alper,Claus Peter Schmitt,Christoph Aufricht,Juan Manuel Sacnun,Silvia Tarantino,Anja Wagner,Klaus Kratochwill,Lilian Kuster,Maria Bartosova,Markus Unterwurzacher,Betti Schaefer,Anton M Lichtenauer

doi:10.3390/biom10121678

Abstract

Long-term clinical outcome of peritoneal dialysis (PD) depends on adequate removal of small solutes and water. The peritoneal endothelium represents the key barrier and peritoneal transport dysfunction is associated with vascular changes. Alanyl-glutamine (AlaGln) has been shown to counteract PD-induced deteriorations but the effect on vascular changes has not yet been elucidated. Using multiplexed proteomic and bioinformatic analyses we investigated the molecular mechanisms of vascular pathology in-vitro (primary human umbilical vein endothelial cells, HUVEC) and ex-vivo (arterioles of patients undergoing PD) following exposure to PD-fluid. An overlap of 1813 proteins (40%) of over 3100 proteins was identified in both sample types. PD-fluid treatment significantly altered 378 in endothelial cells and 192 in arterioles. The HUVEC proteome resembles the arteriolar proteome with expected sample specific differences of mainly immune system processes only present in arterioles and extracellular region proteins primarily found in HUVEC. AlaGln-addition to PD-fluid revealed 359 differentially abundant proteins and restored the molecular process landscape altered by PD fluid. This study provides evidence on validity and inherent limitations of studying endothelial pathomechanisms in-vitro compared to vascular ex-vivo findings. AlaGln could reduce PD-associated vasculopathy by reducing endothelial cellular damage, restoring perturbed abundances of pathologically important proteins and enriching protective processes.

Highlights

Peritoneal dialysis (PD) is a home-based, renal replacement therapy used by 300,000 end stage renal disease patients worldwide
Mass spectrometry data have been deposited into the ProteomeXchange Consortium via the PRIDE partner repository with dataset identifiers PXD022170 and PXD022183. This systematic investigation of the proteomes of endothelial cells exposed to conventional and AlaGln-supplemented PD fluids was performed on two types of endothelial cell samples in a multiplex-approach based on tandem mass tags (TMT), off-line fractionation of digested proteins and shotgun (“bottom-up”) proteomics analysis, using orbitrap-type high resolution mass spectrometers
Quantitative proteomic analysis of arterioles isolated from peritoneal biopsies of children dialyzed with conventional PD fluid (n = 4) or healthy control donors undergoing elective surgery for a reason unrelated to either the kidney or dialysis (n = 5) identified and quantified 3128 proteins, very similar in number to in vitro proteome analysis, demonstrating excellent sensitivity of the approach in these tiny, infrequently available specimens (Supplemental Table S2)

Summary

Introduction

Peritoneal dialysis (PD) is a home-based, renal replacement therapy used by 300,000 end stage renal disease patients worldwide. According to the “3-Pore-Model”, the peritoneal vascular endothelium is considered the primary transport barrier in PD defining membrane function, whereas submesothelial fibrosis only impacts fluid and solute kinetics in severe cases [8,9,10]. It influences peritoneal inflammation and host defenses by allowing translocation of immune cells into the peritoneal cavity [11,12]. Despite the association between ultrafiltration failure and peritoneal vascular changes, little is known about the effect of PD fluids on endothelial cell function and the pathophysiological mechanisms involved

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Conclusion