ABSTRACT: Fatty acid ethyl esters (FAEE), nonoxidative products of ethanol metabolism, are formed by the esterification of fatty acids and ethanol. Alcoholic subjects have high levels of FAEE in the circulation as well as in organs and tissues, especially those most often damaged by ethanol abuse. Our previous studies showed a significant synthesis of FAEE by human mononuclear cells within seconds of exposure to physiologic doses of ethanol. In addition, FAEE inhibited phytohemagglutinin (PHA)-stimulated interleukin-2 production and calcium (Ca(2+)) influx into human mononuclear cells. FAEE also caused a rapid increase in the intracellular cAMP. The mechanism by which alcohol suppresses the immune system remains undetermined.
To evaluate the morphological and physiological effects of FAEE on human mononuclear cells and to study the impact of FAEE on cell viability.
Mononuclear cell fractions of human white blood cells (WBC) were incubated with physiological doses (25 and 50 microM) of ethyl oleate, a representative FAEE, for 15, 30, 60, 120 or 180 minutes. Morphological changes were evaluated by light and transmission electron microscopy (TEM). Lactate dehydrogenase (LDH) release was measured as a physiological indicator of necrosis. Physiological changes were also evaluated by western blots performed on whole-cell lysates of treated and untreated cells and by DNA electrophoresis.
Significant morphological changes were detected in cells exposed to FAEE by both light and TEM. Concentration and time-dependent increases in the rates of apoptosis and necrosis were found by light microscopy and by LDH release, respectively, following 60 minutes exposure to 25 or 50 microM FAEE. One-hour 50 microM FAEE exposure caused activation of the caspase cascade, as demonstrated by Poly (ADP-ribose) Polymerase (PARP) cleavage, and significant DNA damage as a result of necrosis in human mononuclear cells.
These studies provide evidence to support the toxic effects of FAEE on intact human mononuclear cells. The results from our studies also show that both apoptosis and necrosis are modes of cell death in FAEE-treated human mononuclear cells. This may be an important mechanism in alcohol-induced immunosuppression.
Alcoholism Clinical and Experimental Research 04/2008; 32(3):534-43. · 3.34 Impact Factor
ABSTRACT: Fatty acid ethyl esters (FAEE), nonoxidative ethanol metabolites, are produced by the esterification of fatty acids and ethanol. Plasma and serum FAEE correlate linearly with blood ethanol levels and are present in organs most commonly damaged by ethanol abuse. Our previous studies have shown that there is significant synthesis of FAEE by human mononuclear cells within seconds of exposure to physiologic doses of ethanol.
We studied the effects of FAEE on selected early events of mononuclear cell activation that follow stimulation with phytohemagglutinin (PHA). Fatty acid ethyl esters induced changes in cytosolic free calcium ([Ca2+]) levels, the production and secretion of interleukin-2 (IL-2) by the cells, and intracellular cAMP concentrations.
A mononuclear fraction of human white blood cells (WBC) was incubated with physiologic doses of FAEE. For experiments involving IL-2 production and calcium influx, PHA-stimulated cells were incubated with 10, 25, 50, or 100 microM ethyl oleate, a representative FAEE species, for 60 minutes. Interleukin-2 was measured by enzyme immunometeric assay and maximum levels of Ca2+ were monitored by spectrofluorimetry. In other experiments, mononuclear cells were incubated with 10, 25, and 50 microM ethyl oleate for 0.08 to 120 minutes, and then the concentration of cAMP was determined by a cAMP competitive enzyme immunoassay system.
Fatty acid ethyl esters inhibited the PHA-induced IL-2 production and secretion in activated human mononuclear cells. Fatty acid ethyl esters also inhibited PHA-induced [Ca2+] influx into cells in a dose-dependent fashion. There was a rapid increase in the intracellular cAMP concentration of mononuclear cells induced by FAEE, with FAEE dose dependence. The cAMP concentration decreased as the incubation time with FAEE was increased.
Fatty acid ethyl esters inhibited PHA-stimulated IL-2 production and Ca2+ influx into human mononuclear cells and elevated intracellular cAMP concentration. These changes in mononuclear cell signaling may be associated with the immunosuppression associated with alcohol abuse.
Alcoholism Clinical and Experimental Research 08/2006; 30(7):1121-5. · 3.34 Impact Factor
ABSTRACT: Fatty acid ethyl esters (FAEE) are nonoxidative metabolites of ethanol. They are esterification products of ethanol and fatty acids. Fatty acid ethyl esters have been implicated as important mediators of ethanol-induced cytotoxicity, organ damage, and disease. In addition, they serve as specific and sensitive biomarkers for ethanol intake. Following ethanol consumption, FAEE are found in circulating blood bound to albumin or/and lipoproteins.
Using a mononuclear fraction of white blood cells (WBC) exposed to ethanol, we investigated FAEE synthesis. We then determined the amount of uptake of preformed FAEE presented to the cells and compared the amounts of FAEE within the cells that were derived from endogenous synthesis with the amount derived from uptake of exposure FAEE. We also measured the persistence of FAEE within these cells and assessed the fate of the FAEE-associated fatty acid upon FAEE hydrolysis.
A mononuclear fraction of human WBC was incubated with 25, 50, or 100 mM ethanol for 0.08 to 120 minutes, and FAEE synthesis was measured by gas chromatography/mass spectrometry. In other experiments, mononuclear cells were incubated with 25, 50, and/or 100 microM [3H]ethyl oleate, a representative FAEE species, for 0.08-120 minutes, and FAEE uptake and hydrolysis were measured.
The total FAEE formed by treating the cells with 25 mM ethanol, which represents a physiologic dose achievable with excess alcohol intake, greatly exceeded the FAEE within cells derived from uptake of 100 microM ethyl oleate, which represents a supraphysiologic dose. There was hydrolysis of FAEE by human mononuclear cells, with free fatty acids as major metabolites of FAEE hydrolysis. Unlike any other cell type or homogenate studied, the only ethyl ester formed by human mononuclear cells exposed to ethanol was ethyl oleate.
There is significant synthesis of FAEE by human mononuclear cells within seconds of exposure to physiologic doses of ethanol. The amount of FAEE in these cells derived from endogenous synthesis greatly exceeds the amount acquired by exogenous uptake.
Alcoholism Clinical and Experimental Research 04/2006; 30(3):560-6. · 3.34 Impact Factor