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Original article
The paradox of NKp46+ natural killer cells: drivers of severe hepatitis C virus-induced pathology but in-vivo resistance to interferon α treatment
  1. Tom Pembroke1,
  2. Adam Christian2,
  3. Emma Jones1,
  4. Robert K Hills3,
  5. Eddie C Y Wang1,
  6. Awen M Gallimore1,
  7. Andrew Godkin1
  1. 1Institute of Infection & Immunity, Cardiff University, Cardiff, UK
  2. 2Department of Histopathology, University Hospital of Wales, Cardiff, UK
  3. 3Haematology Trials Unit, Institute of Translation, Innovation, Methodology and Engagement, Cardiff University, University Hospital of Wales, Cardiff, UK
  1. Correspondence to Dr Andrew Godkin, Institute of Infection and Immunity, Cardiff University, Henry Wellcome Building, Heath Park, Cardiff CF14 4XN, UK; godkinaj{at}cardiff.ac.uk

Abstract

Objective There is evidence that natural killer (NK) cells help control persistent viral infections including hepatitis C virus (HCV). The phenotype and function of blood and intrahepatic NK cells, in steady state and after interferon (IFN) α treatment has not been fully elucidated.

Design We performed a comparison of NK cells derived from blood and intrahepatic compartments in multiple paired samples from patients with a variety of chronic liver diseases. Furthermore, we obtained serial paired samples from an average of five time points in HCV patients treated with IFNα.

Results Liver NK cells demonstrate a distinct activated phenotype compared to blood manifested as downregulation of the NK cell activation receptors CD16, NKG2D, and NKp30; with increased spontaneous degranulation and IFN production. In contrast, NKp46 expression was not downregulated. Indeed, NKp46-rich NK populations were the most activated, correlating closely with the severity of liver inflammation. Following initiation of IFNα treatment there was a significant increase in the proportion of intrahepatic NK cells at days 1 and 3. NKp46-rich NK populations demonstrated no reserve activation capacity with IFNα treatment and were associated with poor viral control on treatment and treatment failure.

Conclusions NKp46 marks out pathologically activated NK cells, which may result from a loss of homeostatic control of activating receptor expression in HCV. Paradoxically these pathological NK cells do not appear to be involved in viral control in IFNα-treated individuals and, indeed, predict slower rates of viral clearance.

  • CHRONIC VIRAL HEPATITIS
  • HEPATITIS C
  • IMMUNE-MEDIATED LIVER DAMAGE
  • IMMUNOLOGY IN HEPATOLOGY

This is an Open Access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 3.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/3.0/

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