HCV/TLR3-dependent innate and adaptive immune functions of non-parenchymal liver cells are controlled by interleukin-10 and transforming growth factor beta

Abstract

Aims: The regulation of HCV/TLR3-mediated innate immune responses in the liver is not well understood. Therefore, we analyzed the capacity of the anti-inflammatory cytokines interleukin-10 (IL-10) and transforming growth factor beta (TGF-β) to regulate TLR3-activation of non-parenchymal liver cells. Methods: Murine Kupffer cells (KC) and sinusoidal endothelial cells (LSEC) were cultivated in the presence or absence of IL-10 or TGF-β and stimulated by TLR3 ligands. Supernatants from TLR-stimulated NPC were assayed for antiviral activities by viral protection assays(EMCV) on L929 cells. Total RNA was isolated and analyzed by quantitative rt-PCR. Mixed lymphocyte reactions (MLR) were performed to assess T cell activation while activation of transcription factors (NF-κB, IRF-3) was studied by western blot and reporter gene assays, respectively. Expression of cell surface markers (CD80, CD86, CD40, MHC-II) were assessed by FACS. Results: TLR3 induced stimulation of antiviral activities; IFN production and expression of interferon-stimulated genes in NPC were potently suppressed by pretreatment with IL-10 or TGF-β. This correlated with suppression of TLR3 receptor expression and inhibition of TLR-induced activation of NF-κB and IRF-3 in these cells. T cell activation induced by TLR3-stimulated NPC was suppressed by IL-10 and TGF-β which was associated with a downregulation of costimulatory cell surface molecules (CD80, CD86). Conclusions: HCV/TLR3-mediated innate and adaptive immune functions of non-parenchymal liver cells are potently controlled by IL-10 and TGF-β. This is of relevance for the regulation of the local immune responses against viral infections of the liver and the pathogenesis of HCV infection in particular.