ETHANOL SUPPRESSES LPS-INDUCED MESSENGER-RNA FOR NITRIC-OXIDE SYNTHASE-II IN ALVEOLAR MACROPHAGES IN-VIVO AND IN-VITRO

Alcohol abuse increases the incidence and severity of opportunistic lu ng infections and pneumonias. Inducible nitric oxide (NO) synthase (iN OS II) and NO may be a pivotal system in the intracellular bactericida l activity of macrophages. We tested the hypothesis that acute adminis tration of ethanol (ETOH) suppressed Escherichia coli endotoxin lipopo lysaccharide (LPS) mediated upregulation of the iNOS II system in the lung of the rat, in vivo. We also tested the effect of ETOH on alveola r macrophage (AM) production of free NO using microelectrodes. Male Sp rague-Dawley rats were given ETOH (5.5 g/kg, IP) 30 min, before giving intratracheal sterile phosphate buffered saline solution (PBS, 0.5 ml ) or LPS (1 mg/kg in a total volume of 0.5 mi PBS). The isolated lungs were subjected to bronchoalveolar lavage (BAL) 3.5 hr. later. Aliquot s of the BAL fluid were assayed for tumor necrosis factor alpha TNF al pha and reactive nitrogen intermediates (nitrate and nitrite) (RNI) wi th chemiluminescence. Aliquots of AM were incubated 1 hr ex vivo for s pontaneous production of RNI or frozen and assayed for iNOS II mRNA wi th competitor exchange reverse transcriptase polymerase chain reaction (cERT-PCR). The lung was homogenized and assayed for RNI. LPS increas ed BAL fluid TNF alpha and RNI, lung RNI, and the spontaneous producti on of RNI by AM, ex vivo. These effects were inhibited by in vivo admi nistration of inhibitors of iNOS II. LPS increased iNOS mRNA in AM. Th is was unaffected by iNOS inhibitors. ETOH suppressed LPS-induced BAL fluid TNF, iNOS mRNA and RNI production by AM and the lung. In vitro e thanol inhibited LPS + interferon-gamma induced stimulation of free NO in primed AM from 320 nM to 35 nM. Thus, ETOH impairs transcription a nd posttranscriptional upregulation of iNOS II in AM and the lung. ETO H may increase opportunistic lung infections by suppression of the iNO S II system.