Relationships between hepatitis C virus replication and CXCL-8 production in vitro.
The chemokine CXCL-8 (interleukin-8) is induced by many viruses, including hepatitis C virus (HCV). In the current study, we examined CXCL-8 levels in the context of acute and chronic HCV replication in vitro. Two different small interfering RNAs were used to silence CXCL-8 mRNA and protein expression in Huh7 and BB7 replicon cells. HCV RNA synthesis in BB7 cells was inhibited by CXCL-8 knockdown. Furthermore, antibody neutralization of endogenous CXCL-8 activity inhibited HCV replication, while addition of recombinant human CXCL-8 stimulated NS5A protein expression. Moreover, CXCL-8 protein levels correlated positively with HCV RNA levels in four independent subgenomic and genomic replicon lines (R = 0.41, P = 0.0013). However, CXCL-8 mRNA levels correlated inversely with CXCL-8 protein and HCV RNA levels in all replicon lines and in Huh7 cells. Transient replication assays with strongly permissive and weakly permissive Huh7 cells and three independent subgenomic replicons with various replicative capacities revealed that CXCL-8 protein levels were higher in weakly than in strongly permissive cells. The JFH-1 subgenomic replicon, which replicated to high levels in both strongly and weakly permissive Huh7 cells, induced CXCL-8 protein to high levels in both cell types. The data indicate that in the replicon system, CXCL-8 protein levels are positively associated with chronic HCV replication and that CXCL-8 removal inhibits HCV replication. During acute HCV replication, CXCL-8 production may be inhibitory to viruses with low replicative capacity. The data underscore the complex regulation of CXCL-8 mRNA and protein expression and further suggest that in addition to contributing to HCV pathology via proinflammatory actions, CXCL-8 may have opposing antiviral and proviral effects depending on the level of HCV replication, the cellular context, and whether the infection is acute or chronic.
Koo
Bon Chang A
BC
Virology Division, Department of Laboratory Medicine, 359690, 325 9th Avenue, Seattle, WA 98104-2499, USA.
McPoland
Paula
P
Wagoner
Jessica P
JP
Kane
Olivia J
OJ
Lohmann
Volker
V
Polyak
Stephen J
SJ
D045744:Cell Line, Tumor; D016174:Hepacivirus / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D006526:Hepatitis C / Q000276:immunology*; D006801:Humans; D016209:Interleukin-8 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D008099:Liver / Q000187:drug effects / Q000276:immunology / Q000821:virology; D034741:RNA, Small Interfering / Q000235:genetics / Q000494:pharmacology; D012367:RNA, Viral / Q000037:antagonists & inhibitors / Q000378:metabolism; D012093:Replicon / Q000187:drug effects; D014779:Virus Replication / Q000187:drug effects
D016209:Interleukin-8; D034741:RNA, Small Interfering; D012367:RNA, Viral