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Cultured rat mesothelial cells generate hydrogen peroxide: a new player in peritoneal defense?
A Shostak1, E Pivnik, L Gotloib
1Department of Nephrology and Hypertension, Central Emek Hospital, Afula, Israel.
Abstract:
This study was designed to examine whether rat peritoneal mesothelial cells in culture could generate hydrogen peroxide in different experimental conditions. Mesothelial cells, incubated in M-199, spontaneously released hydrogen peroxide. This process was significantly increased by addition of phorbol myristate acetate, as well as of superoxide dismutase to the medium, whereas it was substantially inhibited by catalase. Exposure of mesothelial cells to modified M-199 medium with 1.5% glucose concentration-lactated peritoneal dialysis solution did not seem to interfere either with the spontaneous release of hydrogen peroxide, or with that induced by phorbol myristate acetate. Furthermore, exposure of mesothelial cells to the glucose (4.25%) peritoneal dialysis solution in Medium M-199, was coincident with increased hydrogen peroxide generation, which was significantly higher than the spontaneous release, and not far from that observed with phorbol myristate acetate and superoxide dismutase. So far, it can be inferred from this evidence that peritoneal mesothelial cells in culture are not only endowed with the capability of producing hydrogen peroxide, but they can also be activated to do so in a way comparable to that observed in neutrophils and macrophages. This attribute is one more indication that mesothelial cells play a relevant role in the peritoneal mechanism of defense against infection. On the other hand, continuous exposure of mesothelial cells to glucose-enriched fluids, as occurs in clinical continuous ambulatory peritoneal dialysis, may well also be at the origin of a process of continuous injury, resulting from an increased hydrogen peroxide generation.
Insights
Rat peritoneal mesothelial cells produce hydrogen peroxide, a key component in immune defense. However, prolonged exposure to high-glucose dialysis fluids may cause cellular injury due to increased hydrogen peroxide generation.
Area of Science:
- Cell Biology
- Immunology
- Biochemistry
Background:
- Peritoneal mesothelial cells (PMCs) are crucial for peritoneal membrane integrity and defense.
- Hydrogen peroxide (H2O2) is a reactive oxygen species involved in cellular signaling and defense mechanisms.
- Understanding PMC H2O2 production is vital for assessing peritoneal dialysis (PD) complications.
Purpose of the Study:
- To investigate the capacity of rat PMCs in culture to generate hydrogen peroxide under various conditions.
- To determine the effect of phorbol myristate acetate (PMA), superoxide dismutase (SOD), and catalase on PMC H2O2 release.
- To evaluate the impact of different glucose concentrations in peritoneal dialysis solutions on PMC H2O2 production.
Main Methods:
- Primary rat peritoneal mesothelial cells were cultured in Medium M-199.
- H2O2 release was measured spontaneously and after stimulation with PMA.
- The effects of SOD and catalase on H2O2 release were assessed.
- Cells were exposed to modified M-199 with 1.5% and 4.25% glucose peritoneal dialysis solutions.
Main Results:
- Cultured rat PMCs spontaneously released H2O2.
- PMA and SOD significantly increased H2O2 release, while catalase inhibited it.
- Exposure to 1.5% glucose PD solution did not alter spontaneous or PMA-induced H2O2 release.
- Exposure to 4.25% glucose PD solution significantly increased H2O2 generation compared to spontaneous release.
Conclusions:
- Peritoneal mesothelial cells can produce and release H2O2, indicating a role in peritoneal defense.
- PMC activation to produce H2O2 is comparable to professional phagocytes like neutrophils and macrophages.
- Sustained exposure to high-glucose PD fluids may lead to cellular injury via increased H2O2 production.