title: CD44 participates in IP-10 induction in cells in which hepatitis C virus RNA is replicating, through an interaction with Toll-like receptor 2 and hyaluronan.
abstract: The mechanisms of induction of liver injury during chronic infection with hepatitis C virus (HCV) are not well understood. Gamma interferon (IFN-γ)-inducible protein 10 (IP-10), a member of the CXC chemokine family, is expressed in the liver of chronic hepatitis C (CHC) patients and selectively recruits activated T cells to the sites of inflammation. Recently, it was shown that a low plasma concentration of IP-10 in CHC patients was closely associated with the outcome of antiviral therapy. In this study, we examined the role of the Toll-like receptor (TLR) pathway on IP-10 production in cells replicating HCV. Among the CXC chemokines, the expression of IP-10 was specifically increased in cells replicating HCV upon stimulation with conventional TLR2 ligands. The enhancement of IP-10 production upon stimulation with TLR2 ligands in cells replicating HCV induced CD44 expression. CD44 is a broadly distributed type I transmembrane glycoprotein and a receptor for the glycosaminoglycan hyaluronan (HA). In CHC patients, the expression of HA in serum has been shown to increase in accord with the progression of liver fibrosis, and HA also works as a ligand for TLR2. In the present study, IP-10 production upon HA stimulation was dependent on the expression of TLR2 and CD44, and a direct association between TLR2 and CD44 was observed. These results suggest that endogenous expression of HA in hepatocytes in CHC patients participates in IP-10 production through an engagement of TLR2 and CD44.
authors.affiliation: Department of Molecular Virology, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan.
authors.forename: Takayuki
authors.initials: T
authors.lastname: Abe
authors.forename: Takasuke
authors.initials: T
authors.lastname: Fukuhara
authors.forename: Xiauyu
authors.initials: X
authors.lastname: Wen
authors.forename: Akinori
authors.initials: A
authors.lastname: Ninomiya
authors.forename: Kohji
authors.initials: K
authors.lastname: Moriishi
authors.forename: Yoshihiko
authors.initials: Y
authors.lastname: Maehara
authors.forename: Osamu
authors.initials: O
authors.lastname: Takeuchi
authors.forename: Taro
authors.initials: T
authors.lastname: Kawai
authors.forename: Shizuo
authors.initials: S
authors.lastname: Akira
authors.forename: Yoshiharu
authors.initials: Y
authors.lastname: Matsuura
mesh_terms: D002460:Cell Line; D054357:Chemokine CXCL10 / Q000378:metabolism*; D005786:Gene Expression Regulation; D016174:Hepacivirus / Q000276:immunology*; D022781:Hepatocytes / Q000276:immunology / Q000821:virology; D054884:Host-Pathogen Interactions; D006801:Humans; D018960:Hyaluronan Receptors / Q000378:metabolism*; D006820:Hyaluronic Acid / Q000378:metabolism*; D011485:Protein Binding; D012367:RNA, Viral / Q000378:metabolism*; D051195:Toll-Like Receptor 2 / Q000819:agonists / Q000378:metabolism*; D014779:Virus Replication
chemical_list: C497483:CD44 protein, human; C114753:CXCL10 protein, human; D054357:Chemokine CXCL10; D018960:Hyaluronan Receptors; D012367:RNA, Viral; C495342:TLR2 protein, human; D051195:Toll-Like Receptor 2; D006820:Hyaluronic Acid