Alcohol causes both tolerance and sensitization of rat Kupffer cells via mechanisms dependent on endotoxin

Abstract

Background & Aims: Ethanol causes both tolerance and sensitization of Kupffer cells. This study was designed to evaluate temporal effects of ethanol in an attempt to understand this paradox. Methods: Rats were given ethanol (4 g/kg body wt) intragastrically, and Kupffer cells were isolated 0–48 hours later. After addition of lipopolysaccharide (LPS), intracellular calcium concentration ([Ca 2+] i) was measured using a microspectrofluorometer with the fluorescent indicator fura-2, and tumor necrosis factor α (TNF-α) was measured by enzyme-linked immunosorbent assay. CD14 was evaluated by Western and Northern analysis. Results: Two hours after ethanol administration, the LPS-induced increase in [Ca 2+] i and TNF-α release by Kupffer cells was diminished by 50%, and these parameters were reciprocally enhanced twofold at 24 hours. Sterilization of the gut with antibiotics blocked all effects of ethanol on [Ca 2+] i and TNF-α release completely. Twenty-four hours after ethanol, CD14 in Kupffer cells was elevated about fivefold. Conclusions: Kupffer cells isolated from rats early after ethanol exhibited tolerance to LPS, whereas sensitization was observed later. It is likely that both of these phenomena are caused by gut-derived endotoxin and that sensitization in Kupffer cells is caused by increases in CD14. GASTROENTEROLOGY 1998;115:443-451