The production of interferons is not impaired in primary isolated liver cells from HCV-positive individuals after Toll-like receptor mediated stimulation

Background: The function of the innate immune system of the human liver and its role in the local defense against HCV are not well understood. It has been reported that TLR induced IFN production in HCV-bearing hepatoma cells is blunted by a NS3/4 dependent mechanism. Aim of this study was to investigate the TLR signaling in primary isolated human liver cells from HCV-positive and HCV-negative individuals. Methods: Human liver samples were obtained after tumor resection (n=10) or liver transplantation (n=18; HCV n=7), respectively. Human hepatocytes (n=21) were isolated after liver perfusion and digestion of the liver. In addition endothelial cells (LSEC, n=4), stellate cells (HSC, n=4) and a mix of remaining NPC (n=11) were purified by density centrifugation and MACS separation. Cells were stimulated with TLR1–9 ligands for 6h, RNA was extracted and expression of TNF-α, IL-6, IL-10, a subset of interferons and interferon sensitive genes (ISGs) was determined by qRT-PCR. Results: Expression of pro-inflammatory (TNF-α, IL-6) and anti-inflammatory cytokines (IL-10) was upregulated in hepatocytes and NPC stimulated through TLR1–8, but not TLR9. In contrast, expression of type-I and –II interferons (IFN-α, -β, -γ, IL28A, IL28B and IL29) could only be induced after TLR3 stimulation, resulting in enhanced expression of ISGs (ISG15, IFI-T1, RSAD2 and MXA). The different underlying diseases, the type of surgery, fibrosis stage as well as liver functions tests (ALT, AST, GGT and AP) did not influence TLR signaling in these cells. Primary hepatocytes, but not NPC, from HCV infected patients showed lower IL-10 expression levels after TLR stimulation. Conclusions: In general, liver cells isolated from HCV infected individuals respond to TLR ligands in a similar fashion as compared to HCV-negative controls. In contrast to data generated in hepatoma cell lines, primary hepatocytes from HCV-infected patients are able to produce a variety of IFNs after TLR stimulation.

Hepatitis C - interferon - toll-like receptor