Induction of apoptosis and necrosis in human peripheral blood mononuclear cells by fatty acid ethyl esters.

BACKGROUND: 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. OBJECTIVES: To evaluate the morphological and physiological effects of FAEE on human mononuclear cells and to study the impact of FAEE on cell viability. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.

Xenogenic transfer of isolated murine mitochondria into human rho0 cells can improve respiratory function.

Mitochondrial DNA mutations are the direct cause of several physiological disorders and are also associated with the aging process. The modest progress made over the past two decades towards manipulating the mitochondrial genome and understanding its function within living mammalian cells means that cures for mitochondrial DNA mutations are still elusive. Here, we report that transformed mammalian cells internalize exogenous isolated mitochondria upon simple co-incubation. We first demonstrate the physical presence of internalized mitochondria within recipient cells using fluorescence microscopy. Second, we show that xenogenic transfer of murine mitochondria into human cells lacking functional mitochondria can functionally restore respiration in cells lacking mtDNA. Third, utilizing the natural competence of isolated mitochondria to take up linear DNA molecules, we demonstrate the feasibility of using cellular internalization of isolated exogenous mitochondria as a potential tool for studying mitochondrial genetics in living mammalian cells.