Bartosova Maria, Rudolf Andras, Pichl Sebastian, Schmidt Kathrin, Okun Jürgen G, Straub Beate K, Rutkowski Rafael, Witowski Janusz, Schmitt Claus P
Division of Pediatric Nephrology, Center for Pediatric and Adolescent Medicine, University Hospital Heidelberg, Im Neuenheimer Feld 430, 69120, Heidelberg, Germany.
University of Medical Sciences, Poznan, Poland.
Clin Exp Nephrol. 2016 Aug;20(4):544-551. doi: 10.1007/s10157-015-1192-1. Epub 2015 Nov 2.
BACKGROUND/AIMS: Human peritoneal mesothelial cells (HPMC) secrete phosphatidylcholines (PC) which form a lipid bilayer lining the peritoneum. They prevent frictions and adhesions and act as a barrier to the transport of water-soluble solutes while permitting water flux. PC may play an essential role in peritoneal integrity and function, the role of PD induced HPMC senescence on PC homeostasis, however, is unknown.
HPMC cell lines were isolated from four non-uremic patients. Expression of the three PC synthesis genes (rt-PCR), and cellular storage and secretion of PC (ESI-mass-spectrometry) were analyzed in young and senescent HPMC (>Hayflick-limit).
Senescent cells displayed significantly altered morphology; flow cytometry demonstrated extensive staining for senescence-associated beta galactosidase. Nine different PC were detected in HPMC with palmitoyl-myristoyl phosphatidylcholine (PMPC) being most abundant. In senescent HPMC mRNA expression of the three key PC synthesis genes was 1.5-, 2.4- and 6-fold increased as compared to young HPMC, with the latter, phosphatidylcholine cytidylyltransferase, being rate limiting. Intracellular storage of the nine PC was 75-450 % higher in senescent vs. young HPMC, PC secretion rates were 100-300 % higher. Intracellular PC concentrations were not correlated with the PC secretion rates. Electron microscopy demonstrated lamellar bodies, the primary storage site of PC, in senescent but not in young cells.
Senescent HPMC store and secrete substantially more PC than young cells. Our findings indicate a novel protective mechanism, which should counteract peritoneal damage induced by chronic exposure to PD fluids.
背景/目的：人腹膜间皮细胞（HPMC）分泌磷脂酰胆碱（PC），其形成腹膜的脂质双层。它们可防止摩擦和粘连，并在允许水通量的同时作为水溶性溶质运输的屏障。PC可能在腹膜完整性和功能中起重要作用，然而，腹膜透析（PD）诱导的HPMC衰老对PC稳态的作用尚不清楚。
从四名非尿毒症患者中分离出HPMC细胞系。分析了年轻和衰老的HPMC（超过海弗利克极限）中三种PC合成基因的表达（逆转录-聚合酶链反应）以及PC的细胞储存和分泌（电喷雾电离质谱法）。
衰老细胞显示出明显改变的形态；流式细胞术显示衰老相关β半乳糖苷酶有广泛染色。在HPMC中检测到九种不同的PC，其中棕榈酰-肉豆蔻酰磷脂酰胆碱（PMPC）最为丰富。与年轻的HPMC相比，衰老的HPMC中三种关键PC合成基因的mRNA表达分别增加了1.5倍、2.4倍和6倍，其中后者磷脂酰胆碱胞苷酰转移酶是限速酶。衰老的HPMC中九种PC的细胞内储存量比年轻细胞高75%-450%，PC分泌率高100%-300%。细胞内PC浓度与PC分泌率无关。电子显微镜显示，衰老细胞中有板层小体，即PC的主要储存部位，而年轻细胞中则没有。
衰老的HPMC储存和分泌的PC比年轻细胞多得多。我们的研究结果表明了一种新的保护机制，该机制应能抵消长期暴露于PD液引起的腹膜损伤。
