Dataset Information

Monocytes activate natural killer cells via inflammasome-induced interleukin 18 in response to hepatitis C virus replication.

ABSTRACT: BACKGROUND & AIMS:Production of interferon (IFN)-? by natural killer (NK) cells is attenuated during chronic infection with hepatitis C virus (HCV). We investigated whether this is due to intrinsic or extrinsic mechanisms of NK cells. METHODS:Peripheral blood mononuclear cells (PBMCs) were collected from patients with chronic HCV infection or uninfected blood donors (controls); NK cells and monocytes were isolated or eliminated. We cultured hepatoma cells that express luciferase-tagged subgenomic HCV replicons (Huh7/HCV replicon cells) or their HCV-negative counterparts (Huh7) with NK cells in the presence or absence of other populations of PBMCs. Antiviral activity, cytotoxicity, and cytokine production were assessed. RESULTS:NK cells produced greater amounts of IFN-? when PBMC were cocultured with Huh7/HCV replicon cells than with Huh7 cells; NK cells and PBMCs from controls suppressed HCV replication to a greater extent than those from patients with chronic HCV infection. This antiviral effect was predominantly mediated by tumor necrosis factor (TNF)-? and IFN-?. The antiviral activity of NK cells and their production of IFN-? were reduced when they were used in coculture alone (rather than with PBMC), or after depletion of CD14(+) monocytes, after knockdown of the inflammasome in monocytes, or after neutralization of interleukin-18, which is regulated by the inflammasome. These findings indicate a role for monocytes in NK cell activation. Compared with control monocytes, monocytes from patients with chronic HCV infection had reduced TNF-?-mediated (direct) and reduced NK cell-mediated (indirect) antiviral effects. Control monocytes increased the antiviral effects of NK cells from patients with chronic HCV infection and their production of IFN-?. CONCLUSIONS:Monocytes sense cells that contain replicating HCV and respond by producing interleukin-18 via the inflammasome and by activating NK cells. Patients with chronic HCV infection have reduced monocyte function, attenuating NK cell IFN-?-mediated responses.

SUBMITTER: Serti E

PROVIDER: S-EPMC4469643 | biostudies-literature | 2014 Jul

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Monocytes activate natural killer cells via inflammasome-induced interleukin 18 in response to hepatitis C virus replication.

Serti Elisavet E Werner Jens M JM Chattergoon Michael M Cox Andrea L AL Lohmann Volker V Rehermann Barbara B

Gastroenterology 20140328 1

<h4>Background & aims</h4>Production of interferon (IFN)-γ by natural killer (NK) cells is attenuated during chronic infection with hepatitis C virus (HCV). We investigated whether this is due to intrinsic or extrinsic mechanisms of NK cells.<h4>Methods</h4>Peripheral blood mononuclear cells (PBMCs) were collected from patients with chronic HCV infection or uninfected blood donors (controls); NK cells and monocytes were isolated or eliminated. We cultured hepatoma cells that express luciferase-t ...[more]

PMID: 24685721

Similar Datasets

Project description:ObjectiveSystemic juvenile idiopathic arthritis (sJIA) is characterized by fever, arthritis, rash, hepatosplenomegaly, and macrophage activation syndrome; however, its pathogenesis is still unclear. Elevated serum interleukin (IL)-18 concentrations and decreased natural killer (NK) cell activity are characteristic of active disease; thus, we examined IL-18 signaling in NK cells from sJIA.MethodsWe analyzed mitogen-activated protein kinase (MAPK) p38 and nuclear factor κ light chain enhancer of activated B cells (NFκB) p65 phosphorylation in NK cells after in vitro recombinant IL-18 (rIL-18) stimulation in 31 patients with sJIA. Associations between clinical features, serum IL-18, and phosphorylation intensity were analyzed. Furthermore, we investigated the effects of high IL-18 concentrations on phosphorylation in NK cells.ResultsPatients were divided according to their disease activity: systemic features (n = 8), chronic arthritis (n = 7), remission on medication (n = 10), and remission off medication (n = 6). MAPK p38 and NFκB p65 phosphorylation intensity were the highest in healthy controls, followed by remission off medication, remission on medication (vs. control; MAPK p38, P < 0.01; NFκB p65, P < 0.05), chronic arthritis (P < 0.001, P < 0.001), and systemic features (P < 0.001, P < 0.001). The systemic features group showed a complete defect in phosphorylation. Serum IL-18 was the highest in the systemic features group followed by chronic arthritis, remission on medication (P < 0.01), remission off medication (P < 0.01), and healthy controls (P < 0.01). Phosphorylation intensity was negatively correlated with serum IL-18 (MAPK p38, r2 = 0.42; NFκB p65, r2 = 0.54). Furthermore, healthy control NK cells were cultured with rIL-18; impaired phosphorylation was reproduced in vitro.ConclusionImpaired IL-18 signaling in NK cells correlated with disease activity in sJIA. High serum IL-18 exposure induces impaired MAPK and NFκB phosphorylation in NK cells.

Project description:Although persistent hepatitis B virus (HBV) infection is associated with natural killer (NK) cell dysfunction, it remains obscure whether HBV viral antigens are responsible for NK cell dysfunction in patients with chronic hepatitis B (CHB) infection. In this study, we found that the percentage of NK cells expressing the inhibitory receptor, NKG2A, was increased in CHB patients, and NKG2A blockade restored NK cell function. Furthermore, in CHB patients, the frequency of NK cells expressing NKG2A positively correlated with the number of regulatory T cells (Tregs) and production of interleukin-10 (IL-10) in these Tregs. Moreover, exposure of peripheral blood mononuclear cells (PBMCs) isolated from healthy controls to sera from CHB patients resulted in increased proportion of NKG2A+ NK cells; IL-10 blockade reduced the frequency of NKG2A+ NK cells while increasing the percentage of IFN-?+ NK cells. In addition, stimulation of NK cells and Tregs from healthy controls with CHB sera together with anti-IL-10 antibody increased IFN-? production in the culture supernatant. The frequencies of NKG2A+ NK cells and IL-10+ Tregs, along with serum levels of alanine transferase and HBV DNA, were significantly increased in CHB patients positive for the Hepatitis B e antigen (HBeAg, a marker of viral replication) when compared to HBeAg-negative CHB patients. Importantly, exposure of PBMCs from healthy controls to HBeAg resulted in increased IL-10 production but reduced levels of TNF and IFN-?, and IL-10 blockade rescued the generation of TNF and IFN-? in this assay. The reduced production of TNF and IFN-? was also observed in NK cells and Tregs from healthy controls that were stimulated with HBeAg, while IL-10 blockade increased the secretion of these two cytokines. We conclude that HBeAg induces IL-10 production in Tregs, thereby leading to increased expression of NKG2A on NK cells, which contributes to NK cell dysfunction during CHB infection. These data suggest that HBeAg is associated with NK cell dysfunction in CHB.

Dataset Information

Monocytes activate natural killer cells via inflammasome-induced interleukin 18 in response to hepatitis C virus replication.

Publications

Monocytes activate natural killer cells via inflammasome-induced interleukin 18 in response to hepatitis C virus replication.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets