Cellular fibronectin stimulates hepatocytes to produce factors that promote alcohol-induced liver injury

Figure 6 Secretion of cytokines tumor necrosis factor-alpha and interleukin-6 by cultured hepatocytes isolated from the livers of rats that were pair-fed control and ethanol diets and stimulated with cellular fibronectin. Hepatocytes were cultured in the presence of different concentrations of exogenous cultured hepatocytes (cFn) (0 μg/mL, 0.2 μg/mL, 0.75 μg/mL, 4.0 μg/mL and 7.5 μg/mL) for 20 h. After this time, the level of each cytokine (pg/well) released by the cells into the culture supernatant was determined by ELISA, as described in Material and Methods. In the presence of 7.5 μg/mL cFn, cells from both control and ethanol-fed animals released elevated levels of tumor necrosis factor-alpha (TNF-α) (A) and Interleukin-(IL)-6 (B) compared with corresponding untreated cells, with hepatocytes from ethanol-fed rats secreting significantly higher levels of both cytokines compared with controls. Plasma fibronectin treatment produced no effect on either cell type (inserts, A and B). Data are represented as means ± SEM. Ethanol values significantly different from those of the control are expressed as ^aP < 0.05, and treatment significantly different from untreated cultures is expressed as ^bP < 0.05. (n = 8 - 15 experiments).