Chemokine and Chemokine Receptor Interactions Provide a Mechanism for Selective T Cell Recruitment to Specific Liver Compartments Within Hepatitis C-Infected Liver

Abstract

The role played by chemokines in regulating the selective recruitment of lymphocytes to different tissue compartments in disease is poorly characterized. In hepatitis C infection, inflammation confined to portal areas is associated with a less aggressive course, whereas T cell infiltration of the liver parenchyma is associated with progressive liver injury and cirrhosis. We propose a mechanism to explain how lymphocytes are recruited to hepatic lobules during bursts of necroinflammatory activity in chronic hepatitis C infection. We report here that lymphocytes infiltrating hepatitis C-infected liver express high levels of the chemokine receptors CCR5 and CXCR3. However, whereas the CCR5 ligands macrophage inflammatory protein-1alpha and -1beta were largely confined to vessels within portal tracts, the CXCR3 ligands IFN-inducible protein-10 and monokine-induced by IFN-gamma were selectively up-regulated on sinusoidal endothelium. In vitro, human hepatic sinusoidal endothelial cells secreted IFN-inducible protein-10 and monokine-induced by IFN-gamma in response to stimulation with IFN-gamma in combination with either IL-1 or TNF-alpha. This suggests that intrahepatic Th1 cytokines drive the increased expression of IFN-inducible protein-10 and monokine-induced by IFN-gamma and thereby promote the continuing recruitment of CXCR3-expressing T cells into the hepatic lobule in chronic hepatitis C infection.