title: The hepatitis B e antigen suppresses IL-1β-mediated NF-κB activation in hepatocytes.
abstract: Previous clinical studies have demonstrated an association between the hepatitis B e antigen and Toll-like receptor (TLR) expression and signalling. Therefore, the aim of this study was to develop an in vitro assay to measure the effect of hepatitis B virus proteins, including the precore protein, on signalling mediated by members of the Toll-like/interleukin 1 (TIR) superfamily, by measuring NF-κB promoter activity. The basal level of NF-κB reporter activity was measured in three hepatocyte cell lines (Huh7, HepG2 and PH5CH8) and one kidney cell line (HEK293) using a luciferase assay. All cell lines were virtually refractory to stimulation with lipopolysaccharide; however, PH5CH8 cells had a robust activation of NF-κB in response to IL-1β stimulation, with ∼ 40-fold higher activation than the unstimulated control, a higher degree of activation than that observed in either Huh7 and HepG2, or HEK293 and HEK293-TLR2 cells. In PH5CH8 cells transfected with pCI expression constructs and stimulated with IL-1β, we showed that the precursor form of the precore protein, p25, inhibits NF-κB activation by up to 30% and the cytosolic form, p22, inhibits NF-κB activation by 70%. The core protein, p21, which shares significant homology with the precore protein except for a 10-amino acid extension at the N-terminus, had no effect on NF-κB activation. We hypothesize that the inhibition of IL-1β-mediated NF-κB activation by the precore protein may be a mechanism that allows the virus to persist, suggesting a role for the pool of precore protein that remains intracellular.
authors.affiliation: Research & Molecular Development, Victorian Infectious Diseases Reference Laboratory, North Melbourne, Victoria, Australia.
authors.forename: R
authors.initials: R
authors.lastname: Wilson
authors.forename: N
authors.initials: N
authors.lastname: Warner
authors.forename: K
authors.initials: K
authors.lastname: Ryan
authors.forename: L
authors.initials: L
authors.lastname: Selleck
authors.forename: D
authors.initials: D
authors.lastname: Colledge
authors.forename: S
authors.initials: S
authors.lastname: Rodgers
authors.forename: K
authors.initials: K
authors.lastname: Li
authors.forename: P
authors.initials: P
authors.lastname: Revill
authors.forename: S
authors.initials: S
authors.lastname: Locarnini
mesh_terms: D019677:Artificial Gene Fusion; D002460:Cell Line; D000090266:Chromobox Protein Homolog 5; D004847:Epithelial Cells / Q000276:immunology / Q000821:virology; D017930:Genes, Reporter; D006513:Hepatitis B e Antigens / Q000378:metabolism*; D006515:Hepatitis B virus / Q000276:immunology* / Q000472:pathogenicity*; D022781:Hepatocytes / Q000276:immunology* / Q000821:virology*; D006801:Humans; D057131:Immune Evasion; D053583:Interleukin-1beta / Q000037:antagonists & inhibitors*; D008156:Luciferases / Q000235:genetics / Q000378:metabolism; D016328:NF-kappa B / Q000037:antagonists & inhibitors*
chemical_list: C000715594:CBX5 protein, human; D006513:Hepatitis B e Antigens; D053583:Interleukin-1beta; D016328:NF-kappa B; D000090266:Chromobox Protein Homolog 5; D008156:Luciferases