title: NK cells from HCV-infected patients effectively induce apoptosis of activated primary human hepatic stellate cells in a TRAIL-, FasL- and NKG2D-dependent manner.
abstract: In mouse models it has been shown that natural killer (NK) cells can attenuate liver fibrosis via killing of activated hepatic stellate cells (HSCs) in a NKG2D- and tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-dependent manner. However, only little data exist regarding interactions of human NK cells with HSCs and their potential role in hepatitis C virus (HCV)-associated fibrogenesis. Therefore, purified NK cells from untreated HCV RNA(+) patients (n=33), interferon-α (IFN-α)-treated patients (n=17) and healthy controls (n=18) were coincubated with activated primary HSCs, and were tested for degranulation (CD107a expression) and secretion of IFN-γ and TNF-α, respectively. Induction of HSC apoptosis was analyzed using an active caspase-3 assay. We found that following coincubation with HSCs a significant increase in CD107a expression could be observed in both NK cells from HCV(+) patients and healthy controls, whereas only negligible secretion of IFN-γ and TNF-α could be detected. More importantly, NK cells from untreated HCV RNA(+) patients were significantly more effective in induction of HSC apoptosis (17.8 ± 9.2%) than NK cells from healthy controls (6.2 ± 2.1%; P<0.0001). Additionally, we observed an inverse correlation of liver fibrosis stage and the ability of NK cells to induce HSC apoptosis. Induction of HSC apoptosis was contact dependent and could partly be blocked by antibodies specific for TRAIL, NKG2D and FasL, respectively. It is noteworthy that NK cells from IFN-α-treated HCV(+) patients displayed the highest capability to kill HSCs (27.6 ± 10.5%). Accordingly, pre-stimulation of NK cells with recombinant IFN-α significantly increased the ability of NK cells to induce cell death in primary HSCs and was dependent on upregulated expression of TRAIL. Here we demonstrate that NK cells from HCV-infected patients are highly efficient in inducing apoptosis of activated HSCs. Thus, NK cells may have an important anti-fibrotic role in chronic hepatitis C.
authors.affiliation: Department of Internal Medicine I, University of Bonn, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Glässner
authors.forename: Marianne
authors.initials: M
authors.lastname: Eisenhardt
authors.forename: Benjamin
authors.initials: B
authors.lastname: Krämer
authors.forename: Christian
authors.initials: C
authors.lastname: Körner
authors.forename: Martin
authors.initials: M
authors.lastname: Coenen
authors.forename: Tilman
authors.initials: T
authors.lastname: Sauerbruch
authors.forename: Ulrich
authors.initials: U
authors.lastname: Spengler
authors.forename: Jacob
authors.initials: J
authors.lastname: Nattermann
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000998:Antiviral Agents / Q000008:administration & dosage; D017209:Apoptosis / Q000502:physiology; D016022:Case-Control Studies; D053222:Fas Ligand Protein / Q000502:physiology*; D005260:Female; D055166:Hepatic Stellate Cells / Q000473:pathology* / Q000502:physiology*; D019698:Hepatitis C, Chronic / Q000188:drug therapy / Q000276:immunology / Q000473:pathology* / Q000503:physiopathology*; D006801:Humans; D066298:In Vitro Techniques; D016898:Interferon-alpha / Q000008:administration & dosage; D007371:Interferon-gamma / Q000096:biosynthesis; D007694:Killer Cells, Natural / Q000276:immunology / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D055655:NK Cell Lectin-Like Receptor Subfamily K / Q000502:physiology*; D011092:Polyethylene Glycols / Q000008:administration & dosage; D011994:Recombinant Proteins / Q000008:administration & dosage; D012254:Ribavirin / Q000600:supply & distribution; D053221:TNF-Related Apoptosis-Inducing Ligand / Q000502:physiology*; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis
chemical_list: D000998:Antiviral Agents; C505661:FASLG protein, human; D053222:Fas Ligand Protein; D016898:Interferon-alpha; C527085:KLRK1 protein, human; D055655:NK Cell Lectin-Like Receptor Subfamily K; D011994:Recombinant Proteins; D053221:TNF-Related Apoptosis-Inducing Ligand; C505653:TNFSF10 protein, human; D014409:Tumor Necrosis Factor-alpha; D011092:Polyethylene Glycols; D012254:Ribavirin; D007371:Interferon-gamma; C100416:peginterferon alfa-2a