Maria Bartosova1, Andras Rudolf2, Sebastian Pichl1, Kathrin Schmidt1, Jürgen G Okun1, Beate K Straub3, Rafael Rutkowski2, Janusz Witowski2, Claus P Schmitt4. 1. Division of Pediatric Nephrology, Center for Pediatric and Adolescent Medicine, University Hospital Heidelberg, Im Neuenheimer Feld 430, 69120, Heidelberg, Germany. 2. University of Medical Sciences, Poznan, Poland. 3. Institute of Pathology, University Hospital Heidelberg, Heidelberg, Germany. 4. Division of Pediatric Nephrology, Center for Pediatric and Adolescent Medicine, University Hospital Heidelberg, Im Neuenheimer Feld 430, 69120, Heidelberg, Germany. claus.peter.schmitt@med.uni-heidelberg.de.
Abstract
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. METHODS: 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). RESULTS: 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. CONCLUSION: 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.
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. METHODS: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). RESULTS: 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. CONCLUSION: 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.
Authors: John D Williams; Kathrine J Craig; Nicholas Topley; Christopher Von Ruhland; Maureen Fallon; Geoffrey R Newman; Ruth K Mackenzie; Geraint T Williams Journal: J Am Soc Nephrol Date: 2002-02 Impact factor: 10.121
Authors: Thorsten O Bender; Michael Böhm; Klaus Kratochwill; Regina Vargha; Andrea Riesenhuber; Janusz Witowski; Achim Jörres; Anders Wieslander; Christoph Aufricht Journal: Nephrol Dial Transplant Date: 2010-08-16 Impact factor: 5.992