Silybin inhibits interleukin-1β-induced production of pro-inflammatory mediators in canine hepatocyte cultures

Hepatocytes are highly susceptible to cytokine stimulation and are fundamental to liver function. We established primary canine hepatocyte cultures to study effects of anti-inflammatory agents with hepatoprotective properties. Hepatocyte cultures were incubated with control media alone, silybin (SB), or the more bioavailable silybin-phosphatidylcholine complex (SPC), followed by activation with interleukin-1 beta (IL-1 beta; 10 ng/mL). Inflammatory response was measured by prostaglandin E2 (PGE(2)), interleukin-8 (IL-8), and monocyte chemotactic protein-1 (MCP-1) production and also nuclear factor-kappa B (NF-kappa B) translocation. Hepatocyte cultures continued production of the phenotypic marker albumin for more than 7 days in culture. IL-1 beta exposure increased PGE(2), IL-8, and MCP-1 production, which was paralleled by NF-kappa B translocation from the cytoplasm to the nucleus. Pretreatment with SB and SPC significantly inhibited IL-1 beta-induced production of pro-inflammatory markers and attenuated NF-kappa B nuclear translocation. We demonstrate for the first time that primary canine hepatocyte cultures can be maintained in culture without phenotypic loss. The observation that hepatocyte cultures respond to pro-inflammatory IL-1 beta activation indicates hepatocytes as primary cellular targets of extrinsic IL-1 beta. The ability of SB and SPC to inhibit hepatocyte culture activation by IL-1 beta reinforces the notion of their hepatoprotective effects. Our primary canine hepatocyte culture model facilitates identification of hepatoprotective agents and their mechanism of action.