Modulation of hyperoxia-induced TNF-alpha expression in the newborn rat lung by thalidomide and dexamethasone

The effect of high oxygen concentrations on lungs of neonatal rats was stud ied. In addition, some oxygen-exposed animals were treated with either dexa methasone or thalidomide. No gross histologic changes were noted in the lun gs following exposure to 95% oxygen nor were there changes in the total num ber or the phenotypic distribution of BAL cells obtained from these lungs c ompared to lungs from air exposed (control) neonatal rats. The majority of the BAL cells were CD45+ leukocytes (macrophages). However, when BAL cells were exposed to LPS in vitro, TNF-alpha production was higher in cells from rats exposed to 95% oxygen compared to cells from rats exposed to ambient air. In addition, lung TNF-alpha and IL-6 mRNA levels were increased after exposure to 95% oxygen. In the lungs of animals treated with either dexamet hasone or thalidomide, TNF-alpha mRNA levels were reduced, while only dexam ethasone treatment also reduced IL-6 mRNA levels.