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Human peritoneal mesothelial cells produce nitric oxide: induction by cytokines
1Department of Medicine, Taipei Veterans General Hospital, Taiwan. jychen@vghtpe.gov.tw
Objective:
To investigate the induction of nitric oxide synthase type II (iNOS) in human peritoneal mesothelial cells (HPMC) using cytokines and bacterial lipopolysaccharide (LPS).
Design:
Confluent monolayers of HPMC were exposed to cytokines [tumor necrosis factor alpha (TNFalpha), interleukin-1 beta (IL-1beta), interferon gamma (IFNgamma)] or LPS, individually or in various double and triple combinations, for 24-72 hours. Concentrations of nitrate and nitrite in the media were quantified using the Griess reaction and used as indirect indices of nitric oxide (NO) production. The expression of iNOS was assessed using reverse transcriptase-polymerase chain reaction (RT-PCR) and Western blot.
Results:
Neither single cytokines nor LPS was able to induce iNOS mRNA or NO production. Both double combinations of TNFalpha + IFNgamma and IL-1beta + IFNgamma were able to induce iNOS mRNA expression, but only TNFalpha + IFNgamma induced significant NO production. The triple combination of TNFalpha + IFNgamma + IL-1beta induced even more NO production than TNFalpha + IFNgamma. There was no constitutive NO synthase type III (eNOS) expression in HPMC.
Conclusions:
Certain combinations of cytokines could stimulate cultured HPMC to produce NO, and HPMC might be a source of intraperitoneal NO production during peritonitis.
Insights
Certain cytokine combinations, but not single agents, induce nitric oxide (NO) production in human peritoneal mesothelial cells (HPMC). HPMC may be a source of NO during peritonitis.
Area of Science:
- Cell Biology
- Immunology
- Physiology
Background:
- Human peritoneal mesothelial cells (HPMC) play a role in the peritoneal environment.
- Nitric oxide (NO) is a critical signaling molecule involved in various physiological and pathological processes.
- Understanding NO production in HPMC is important for conditions like peritonitis.
Purpose of the Study:
- To investigate the induction of inducible nitric oxide synthase type II (iNOS) in HPMC.
- To determine the effects of cytokines and bacterial lipopolysaccharide (LPS) on iNOS expression and NO production in HPMC.
Main Methods:
- Cultured HPMC were treated with individual or combined cytokines (TNFalpha, IL-1beta, IFNgamma) and LPS.
- Nitrate and nitrite levels were measured using the Griess reaction as indicators of NO production.
- iNOS mRNA and protein expression were analyzed via RT-PCR and Western blot.
Main Results:
- Single cytokines or LPS did not induce iNOS mRNA or NO production.
- Combinations of TNFalpha + IFNgamma and IL-1beta + IFNgamma induced iNOS mRNA expression.
- TNFalpha + IFNgamma significantly induced NO production, with further enhancement by IL-1beta.
Conclusions:
- Specific cytokine combinations can stimulate NO production in cultured HPMC.
- HPMC represent a potential source of intraperitoneal NO during peritonitis.