Characterization of gene expression profile in rat Kupffer cells stimulated with IFN-alpha or IFN-gamma.

Kupffer cells are intrasinusoidal space located macrophages with phagocytic capacity. Interferons are cytokines with antiviral, antiproliferative and immunomodulatory activities which may influence the activity of Kupffer cells. Aim of this study was to evaluate Kupffer cell gene expression after interferon-alpha or interferon-gamma stimulation in order to investigate a link between these cytokines and macrophage activation. Rat Kupffer cells were cultured for 24 h and divided into three groups: unstimulated; stimulated with interferon-alpha and stimulated with interferon-gamma. After 8 h stimulation total RNA was extracted and processed according to Affymetrix protocols and hybridised on R34A microarray gene set. Data analyses was performed using Microarray Analysis Suite 5.0 software. Genes showing remarkably different expression in microarray analysis were confirmed by real-time PCR. Nearly 4000 out of the 8800 genes represented in the array were expressed by Kupffer cells. Among these, interferon-alpha up-regulates 91 genes by over two-fold (antiviral, antigen processing and presentation, and tumour suppressor/proapoptotic genes) and down-regulates 72 genes by 50% or more. Interferon-gamma up-regulates 70 genes by over two-fold and down-regulates 78 genes by 50% or more. Most of the genes induced by interferon-alpha are also induced by interferon-gamma. Down-regulated genes include growth factors and genes involved in cell cycle/proliferation. Real-time PCR confirms the results of the array. Interferons directly target rat Kupffer cells and are involved in the regulation of a wide variety of genes. Their expression profile shed light onto molecular mechanism of Kupffer cells activation in specific pathways such as antiviral and antitumour processes.