Meconium Induces Expression of Inducible NO Synthase and Activation of NF-|[kgr]|B in Rat Alveolar Macrophages

摘要

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-γ. 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 p p ?4?10?10 M) or dexamethasone (10?4?10?6 M) effectively inhibited the meconium-induced NO production (p In vitro steroids down-regulated the iNOS expression, thus suggesting a potential to down-regulate NO-mediated inflammation in neonates with meconium aspiration syndrome.Abbreviations: LPS, lipopolysaccharide; RT-PCR, reverse transcriptase-PCR; NO, nitric oxide; iNOS, inducible nitric oxide synthase; IFN-γ, interferon-γ; NF-κB, nuclear factor-kappa B; CHX, cycloheximide; EMSA, electrophoretic mobility shift assay; MAS, meconium aspiration syndrome; NO2?, nitrite; G3PDH, glyceraldehyde-3-phosphate dehydrogenase