CYTOKINE-INDUCED NEUTROPHIL CHEMOATTRACTANT RELEASE FROM HEPATOCYTES IS MODULATED BY KUPFFER CELLS

To clarify the role of intercellular communication in the liver during accumulation of neutrophils, the release of cytokine-induced neutroph il chemoattractant (CINC) (interleukin-8 [IL-8] related protein in rod ents) by hepatocytes was investigated in the presence of Kupffer cell- conditioned medium in vitro. Kupffer cells were prepared by perfusion of rat liver with collagenase followed by centrifugation on a metrizam ide gradient and were cultured in the presence or absence of lipopolys ac charide (LPS). The conditioned medium was collected after 24 hours, and rat hepatocytes were cultured in the presence or absence of Kupff er cell-conditioned medium. An amount of CINC in the culture supernata nt was measured by western blotting analysis and enzyme-linked immunos orbent assay (ELLSA), and expression of its messenger RNA (mRNA) was a ssessed by the polymerase chain reaction. LPS-stimulated Kupffer cell- conditioned medium enhanced an expression of CINC mRNA in hepatocytes and increased the production of CINC by hepatocytes, Enhanced producti on of CINC was not shown when the Kupffer cell-conditioned medium was pretreated with heat (56 degrees C, 30 minutes). The production of CIN C by hepatocytes in the presence of the LPS-stimulated Kupffer cell-co nditioned medium was reduced by an antibody against interleukin 1 beta (IL-1 beta), but not by antibodies against tumor necrosis factor alph a (TNF-alpha) or LPS. These results suggest that production of CINC by hepatocytes could be regulated by IL-1 beta released from Kupffer cel ls, leading to neutrophil accumulation during liver injury, because th is protein is a strong chemoattractant for neutrophils.