Cytokines induced during chronic hepatitis B virus infection promote a pathway for NK cell–mediated liver damage

C Dunn, M Brunetto, G Reynolds… - The Journal of …, 2007 - rupress.org
C Dunn, M Brunetto, G Reynolds, T Christophides, PT Kennedy, P Lampertico, A Das…
The Journal of experimental medicine, 2007rupress.org
Hepatitis B virus (HBV) causes chronic infection in more than 350 million people worldwide.
It replicates in hepatocytes but is non-cytopathic; liver damage is thought to be immune
mediated. Here, we investigated the role of innate immune responses in mediating liver
damage in patients with chronic HBV infection. Longitudinal analysis revealed a temporal
correlation between flares of liver inflammation and fluctuations in interleukin (IL)-8,
interferon (IFN)-α, and natural killer (NK) cell expression of tumor necrosis factor–related …
Hepatitis B virus (HBV) causes chronic infection in more than 350 million people worldwide. It replicates in hepatocytes but is non-cytopathic; liver damage is thought to be immune mediated. Here, we investigated the role of innate immune responses in mediating liver damage in patients with chronic HBV infection. Longitudinal analysis revealed a temporal correlation between flares of liver inflammation and fluctuations in interleukin (IL)-8, interferon (IFN)-α, and natural killer (NK) cell expression of tumor necrosis factor–related apoptosis-inducing ligand (TRAIL) directly ex vivo. A cross-sectional study confirmed these findings in patients with HBV-related liver inflammation compared with healthy carriers. Activated, TRAIL-expressing NK cells were further enriched in the liver of patients with chronic HBV infection, while their hepatocytes expressed increased levels of a TRAIL death–inducing receptor. IFN-α concentrations found in patients were capable of activating NK cells to induce TRAIL-mediated hepatocyte apoptosis in vitro. The pathogenic potential of this pathway could be further enhanced by the ability of the IFN-α/IL-8 combination to dysregulate the balance of death-inducing and regulatory TRAIL receptors expressed on hepatocytes. We conclude that NK cells may contribute to liver inflammation by TRAIL-mediated death of hepatocytes and demonstrate that this non-antigen–specific mechanism can be switched on by cytokines produced during active HBV infection.
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