Abstract |
Meconium aspiration causes intensive inflammatory reactions in the lungs, and may lead to neonatal respiratory disorder. Infiltrated inflammatory cells, particularly macrophages, play an important role in such an inflammation. A rat alveolar macrophage cell line (ATCC8383) was exposed to meconium alone or in combination with dexamethasone, budesonide, or interferon-gamma. Nitric oxide (NO) accumulation in the supernatant of the cell culture was detected by Griess reaction, and mRNA of inducible NO synthase (iNOS) expression was detected by reverse transcriptase-PCR. Nuclear factor-kappa B was analyzed by electrophoretic mobility shift assay, and iNOS location and nuclear factor-kappa B transactivation were determined by immunostaining. Our results showed that meconium was capable of inducing production of NO and expression of iNOS in alveolar macrophages in a dose- (1-25 mg/mL, p < 0.05) and time- (4-48 h, p < 0.05) dependent manner. This capability of meconium could be further enhanced in the presence of interferon-gamma (100 IU/mL, p < 0.05). Budesonide (10(-4)-10(-10) M) or dexamethasone (10(-4)-10(-6) M) effectively inhibited the meconium-induced NO production (p < 0.05). Using the protein synthesis inhibitor cycloheximide, we demonstrated that meconium directly induced iNOS in macrophages. Furthermore, meconium also triggered nuclear factor-kappa B activation, a mechanism possibly responsible for the iNOS expression. Our findings suggest that meconium is a potent inflammatory stimulus, resulting in iNOS expression, leading to overproduction of NO from the macrophages, which may be of pathogenic importance in meconium aspiration syndrome. In vitro steroids down-regulated the iNOS expression, thus suggesting a potential to down-regulate NO-mediated inflammation in neonates with meconium aspiration syndrome.
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Authors | Y H Li, Z Q Yan, A Brauner, K Tullus |
Journal | Pediatric research
(Pediatr Res)
Vol. 49
Issue 6
Pg. 820-5
(Jun 2001)
ISSN: 0031-3998 [Print] United States |
PMID | 11385144
(Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
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Chemical References |
- Anti-Inflammatory Agents
- DNA Primers
- Glucocorticoids
- NF-kappa B
- RNA, Messenger
- Nitric Oxide
- Budesonide
- Dexamethasone
- NOS2 protein, human
- Nitric Oxide Synthase
- Nitric Oxide Synthase Type II
- Nos2 protein, rat
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Topics |
- Animals
- Anti-Inflammatory Agents
(pharmacology)
- Base Sequence
- Budesonide
(pharmacology)
- Cell Line
- DNA Primers
(genetics)
- Dexamethasone
(pharmacology)
- Gene Expression
- Glucocorticoids
(pharmacology)
- Humans
- Infant, Newborn
- Macrophages, Alveolar
(drug effects, metabolism)
- Meconium
(metabolism)
- Meconium Aspiration Syndrome
(genetics, metabolism)
- NF-kappa B
(metabolism)
- Nitric Oxide
(biosynthesis)
- Nitric Oxide Synthase
(genetics, metabolism)
- Nitric Oxide Synthase Type II
- RNA, Messenger
(genetics, metabolism)
- Rats
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