[Alcohol abuse as a risk factor for ARDS].
Morbidity and mortality rates of ARDS (acute respiratory distress syndrome) are high in patients with a history of chronic alcohol abuse. In addition to susceptibility to lung infection, alteration of local cellular functions in the lung has recently been proposed as a new mechanism of exacerbation of ARDS in patients with a history of chronic alcohol abuse. Clinical studies and studies using animal experiments have shown that a decrease in lung glutathione levels is associated with exacerbation of ARDS in chronic alcohol abuse. In the alcoholic lung, depletion of glutathione increases oxidative stress derived from activated neutrophils, resulting in decreased surfactant production, apoptosis and increased permeability of alveolar epithelial type II cells, in which TGF-beta1 may be involved. Acetoaldehyde has been suggested to be involved in the mechanism of exacerbation of ARDS by inducing lung remodeling through stimulation of fibronectin expression following nicotinic acetylcholine receptor stimulation and CREB activation in chronic alcohol abuse. More recently, antagonists of angiotensin II type-1 receptor (AT1 receptor) have been shown to prevent glutathione depletion, increase in TGF-beta1 expression and lung edema in endotoxemic rats with chronic alcohol administration. On the other hand, macrophage-derived prostaglandin E2 plays a protective role at an initial phase of ARDS by inhibiting cytokine production by macrophages and extravascular invasion of activated neutrophils. Our recent studies have shown that LPS-induced COX-2 expression and subsequent prostaglandin E2 production in rat alveolar macrophages are inhibited by ethanol incubation in vitro and ethanol administration in vivo. Only a decade has passed since alcohol abuse was demonstrated to be associated with increased mortality of ARDS and future studies are needed to clarify the mechanism underlying alcohol-induced exacerbation of ARDS.