title: Vitamin D Metabolites Inhibit Hepatitis C Virus and Modulate Cellular Gene Expression.
abstract: OBJECTIVE
  Previous studies suggest that low serum 25-hydroxyvitamin D [25(OH) D] levels are associated with reduced responsiveness to interferon and ribavirin therapy. We investigated the impact of vitamin D metabolites on HCV and cellular gene expression in cultured hepatoma cells.
  
  
  METHODS
  HCV Replicon cell lines stably expressing luciferase reporter constructs (genotype 1b and 2a replicon) or JC1-Luc2a were incubated in the presence of vitamin D2, vitamin D3 or 1,25-dihydroxyvitamin D3 (1,25(OH)2D3). Presence of HCV was quantified by a luciferase reporter assay and immunoblot of the Core protein. Synergy of interferon-alpha A/D (IFN-α) and 1,25(OH)2D3 was evaluated using the Chou-Talalay method. Cellular gene expression by microarray analysis using Illumina Bead Chips and real-time quantitative PCR.
  
  
  RESULTS
  Vitamin D2, D3 and 1,25(OH)2D3 each demonstrated anti-HCV activity at low micro molar concentrations. In vitro conversion from D3 to 25(OH)D3 was shown by LC/MS/MS. Combination indices of 1,25(OH)2D3 and IFN-α demonstrated a synergistic effect (0.23-0.46) and significantly reduced core expression by immunoblot. Differentially expressed genes were identified between Huh7.5.1 cells in the presence and absence of 1,25(OH)2D3 and HCV. Genes involved with classical effects of vitamin D metabolism and excretion were activated, along with genes linked to autophagy such as G-protein coupled receptor 37 (GPR37) and Hypoxia-inducible factor 1-alpha (HIF1a). Additionally, additive effects of 1,25(OH)2D3 and IFN-α were seen on mRNA expression of chemokine motif ligand 20 (CCL20).
  
  
  CONCLUSIONS
  This study shows that vitamin D reduces HCV protein production in cell culture synergistically with IFN-α. Vitamin D also activates gene expression independently and additively with IFN-α and this may explain its ability to aid in the clearance of HCV in vivo.
authors.affiliation: Texas Liver Institute, Department of Hepatology, University of Texas Health Science Center San Antonio, USA ; Division of Infectious Diseases, University of California, San Diego, USA.
authors.forename: Julio A
authors.initials: JA
authors.lastname: Gutierrez
authors.affiliation: Division of Infectious Diseases, University of California, San Diego, USA.
authors.forename: Krysten A
authors.initials: KA
authors.lastname: Jones
authors.affiliation: Division of Infectious Diseases, University of California, San Diego, USA.
authors.forename: Roxana
authors.initials: R
authors.lastname: Flores
authors.affiliation: Division of Infectious Diseases, University of California, San Diego, USA ; Clinical and Experimental Sciences, Southampton General Hospital, USA.
authors.forename: Akul
authors.initials: A
authors.lastname: Singhania
authors.affiliation: Division of Infectious Diseases, University of California, San Diego, USA ; Clinical and Experimental Sciences, Southampton General Hospital, USA.
authors.forename: Christopher H
authors.initials: CH
authors.lastname: Woelk
authors.affiliation: Division of Infectious Diseases, University of California, San Diego, USA.
authors.forename: Robert T
authors.initials: RT
authors.lastname: Schooley
authors.affiliation: Division of Infectious Diseases, University of California, San Diego, USA.
authors.forename: David L
authors.initials: DL
authors.lastname: Wyles
keywords: Hepatitis C Virus; Interferon; Ribavirin therapy