Effect of chronic ethanol feeding on Kupffer cell-mediated antitumor cell activity

Immune response modulation in acutely ethanol-intoxicated, acutely diabetic male and female rats

We examined how acute diabetes mellitus and acute ethanol intoxication modulate factors that mediate immune responses as a basis for explaining the increased susceptibility to infection in these two conditions. Our working hypothesis is that ethanol intoxication in diabetes compromises host defense mechanisms to a greater extent than observed in each condition alone. Male and female rats were made diabetic with streptozotocin (65 mg/kg, i.p.). Forty-eight hours after administration of streptozotocin, rats either received no treatment (control group) or were treated with (1) ethanol (bolus injection of 1.75 g/kg, followed by a 3-h infusion at the rate of 300 mg/kg/h), (2) lipopolysaccharide [(LPS); 0.9 mg/kg], or (3) a combination of LPS+ethanol. At the end of 3 h, rats were killed, and the livers were digested by perfusion with collagenase-containing Hanks' balanced salt solution to isolate hepatocytes and Kupffer cells. To measure chemokine generation, hepatocytes (2.5x10(5) cells per well) and Kupffer cells (1x10(6) cells per well) were cultured for 20 h, and the supernatant was used to measure cytokine-induced neutrophil chemoattractant (CINC) and regulated on activation, normal T-cell expressed and secreted (RANTES) chemokines. Phagocytosis by Kupffer cells was measured by flow cytometry and expressed as mean channel fluorescence intensity (MCF). Induction of diabetes as well as treatment of nondiabetic rats with LPS, ethanol, or LPS+ethanol caused depression of MCF values of Kupffer cells. However, treatment of the diabetic male and female rats with LPS and LPS+ethanol increased the MCF values relative to those of Kupffer cells obtained from untreated diabetic rats, but administration of ethanol to diabetic rats did not have a similar effect. The induction of diabetes caused an increase in CINC generation by Kupffer cells obtained from male rats, but not from female rats. This diabetes-induced elevation of chemoattractant factor was decreased when diabetic animals were treated with LPS, ethanol, or LPS+ethanol, and the sex difference was obliterated. Thus, the induction of diabetes as well as treatment with LPS, ethanol, or LPS+ethanol in nondiabetic rats depressed the phagocytic capability of Kupffer cells, whereas the presence of endotoxemia (administration of the endotoxin LPS) or administration of LPS+ethanol reversed the diabetic effect, but ethanol intoxication did not. These findings seem to indicate a persistence of depression of host defense capacity in the ethanol-intoxicated diabetic condition. This is further reinforced by the depression of the diabetes-induced enhancement of chemotaxis when the diabetic rats became intoxicated.

Alcohol and cancer

A great number of epidemiological data have identified chronic alcohol consumption as a significant risk factor for upper alimentary tract cancer, including cancer of the oropharynx, larynx, and the esophagus, and for the liver. In contrast to those organs, the risk by which alcohol consumption increases cancer in the large intestine and in the breast is much smaller. However, although the risk is lower, carcinogenesis can be enhanced with relatively low daily doses of ethanol. Considering the high prevalence of these tumors, even a small increase in cancer risk is of great importance, especially in those individuals who exhibit a higher risk for other reasons. The epidemiological data on alcohol and other organ cancers are controversial and there is at present not enough evidence for a significant association. Although the exact mechanisms by which chronic alcohol ingestion stimulates carcinogenesis are not known, experimental studies in animals support the concept that ethanol is not a carcinogen, but under certain experimental conditions is a cocarcinogen and/or (especially in the liver) a tumor promoter. The metabolism of ethanol leads to the generation of acetaldehyde and free radicals. These highly reactive compounds bind rapidly to cell constituents and possibly to DNA. Acetaldehyde decreases DNA repair mechanisms and the methylation of cytosine in DNA. It also traps glutathione, an important peptide in detoxification. Furthermore, it leads to chromosomal aberrations and seems to be associated with tissue damage and secondary compensatory hyperregeneration. More recently, the finding of considerable production of acetaldehyde by gastrointestinal bacteria was reported. Other mechanisms by which alcohol stimulates carcinogenesis include the induction of cytochrome P4502E1, associated with an enhanced activation of various procarcinogens present in alcoholic beverages, in association with tobacco smoke and in diets, a change in the metabolism and distribution of carcinogens, alterations in cell cycle behavior such as cell cycle duration leading to hyperregeneration, nutritional deficiencies such as methyl, vitamin A, folate, pyrridoxalphosphate, zinc and selenium deficiency, and alterations of the immune system, eventually resulting in an increased susceptibility to certain viral infections such as hepatitis B virus and hepatitis C virus. In addition, local mechanisms in the upper gastrointestinal tract and in the rectum may be of particular importance. Such mechanisms lead to tissue injury such as cirrhosis of the liver, a major prerequisite for hepatocellular carcinoma. Thus, all these mechanisms, functioning in concert, actively modulate carcinogenesis, leading to its stimulation.

The development and utility of a defined muscle and fat co-culture system

The utility of co-culture systems in defining the interactions between two different cell types has been well documented in the literature but is a relatively new tool for use in the study of cells derived from normal muscle tissue from meat animals. The majority of myonuclei in postnatal skeletal muscle cells (myofibers) result from satellite cell proliferation, differentiation and fusion with existing myofibers. As such, satellite cell culture systems that mimic postnatal myofibers have great potential for delineating the process of growth and repair of muscle mass. Other ways to simulate the environment of postnatal myofibers might include the development of co-culture systems using satellite cells, or satellite cell-derived myotubes, and other mesodermal cells commonly found associated with muscle tissue in vivo. This brief review describes our initial efforts to develop a defined satellite cell and preadipocyte co-culture system. We provide useful information about defined media requirements and requirements for proper cell orientation and growth on two different growth planes. We present summary data to suggest that differences were found between members of the insulin-like growth factor (IGF) and IGF-binding protein (IGFBP) families of polypeptides, when conditioned media samples were analyzed from co-cultures composed of 3T3-L1 preadipocytes and satellite cells (with different propensities to undergo morphological fusion to form multinucleated myotubes). We also provide information about potential problems to avoid when initiating and conducting co-culture experiments. Such a co-culture system has application in the study of human obesity and also in the regulation of fat deposition in meat animals.