C-C Chemokine Ligand 2/Monocyte Chemoattractant Protein-1 Directly Inhibits NKT Cell IL-4 Production and Is Hepatoprotective in T Cell-Mediated Hepatitis in the Mouse

摘要

T cell-mediated liver diseases are associated with elevated serum levels of C-C chemokine ligand 2 (CCL2)/monocyte chemoattractant protein-1 (MCP-1). However, the extent to which the actions of CCL2/MCP-1 contribute to the pathogenesis of T cell-mediated hepatitis remains incompletely understood. Con A-induced hepatitis is a liver-specific inflammation mediated by activated T cells and is driven by an up-regulation of the hepatic expression of TNF-α, IFN-γ, and IL-4. The present study examined the role of CCL2/MCP-1 in the pathogenesis of T cell-mediated hepatitis induced by Con A administration in the mouse. We demonstrate a novel hepatoprotective role for CCL2/MCP-1 during Con A-induced hepatitis, because CCL2/MCP-1 neutralization strikingly enhanced hepatic injury, both biochemically and histologically, after Con A administration. Furthermore, CCL2/MCP-1 neutralization was associated with a significant reduction in the hepatic levels of TNF-α and IFN-γ, but with a significant increase in hepatic IL-4 levels. Moreover, IL-4 production and CCR2 expression by Con A-stimulated CD3+NK1.1+ T cells was significantly reduced by rMCP-1 treatment in vitro. In summary, we propose that CCL2/MCP-1 fulfills a novel anti-inflammatory role in T cell-mediated hepatitis by inhibiting CD3+NK1.1+ T cell-derived IL-4 production through direct stimulation of its specific receptor CCR2. These findings may have direct clinical relevance to T cell-mediated hepatitis.