Fine characterization of intrahepatic NK cells expressing natural killer receptors in chronic hepatitis B and C

Background. To explore the role of natural killer (NK) cells in the process of hepatitis B virus (HBV) clearance and whether their phenotype is related to antiviral treatment outcome in chronic hepatitis B (CHB) patients. Method. We performed a single-center prospective cohort study to analyze changes of NK cells at weeks 12 and 24 from baseline in CHB patients who received PEGylated-interferon- (PEG-IFN-) α-2a versus entecavir. The frequencies of NK, CD56bright, CD56dim, IFNAR2+, NKp46+, NKp46bright, and NKp46dim NK cells and mean fluorescence intensity (MFI) of receptors NKp46 and IFNAR2 on the surface of NK cells were measured. Subgroup analyses were performed by comparing treatment responders versus nonresponders with aforementioned parameters in each group. Results. In PEG-IFN-α-treated patients, posttreatment CD56bright NK cell frequency increased, but CD56dim NK cell frequency decreased. Additionally, receptor NKp46 and IFNAR2 expression enhanced. In entecavir-treated patients, although NK cell frequency increased, CD56bright and CD56dim NK cell frequencies and IFNAR2 expression did not differ between baseline and posttreatment. In subgroup analyses, posttreatment CD56bright NK cell frequency and IFNAR2 expression significantly increased in PEG-IFN-α responders from baseline, while changes were absent in PEG-IFN-α nonresponders and entecavir treatment responders. Among patients with HBV viremia after entecavir therapy, NK cell frequency significantly increased, whereas NKp46bright and IFNAR2+ NK frequency and IFNAR2 MFI significantly decreased at 12 and 24 weeks from baseline. Conclusions. In CHB patients, PEG-IFN-α treatment significantly enhanced NK cell frequency and function when compared to entacavir. Positive treatment responses to either interferon or entecavir were associated with NK cell function improvement. This trial is registered with clinical trial registration no. NCT03208998.

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The Good and the Bad of Natural Killer Cells in Virus Control: Perspective for Anti-HBV Therapy

International Journal of Molecular Sciences ◽

10.3390/ijms20205080 ◽

2019 ◽

Vol 20 (20) ◽

pp. 5080 ◽

Cited By ~ 3

Author(s):

Paola Fisicaro ◽

Marzia Rossi ◽

Andrea Vecchi ◽

Greta Acerbi ◽

Valeria Barili ◽

...

Keyword(s):

T Cells ◽

Chronic Hepatitis ◽

T Cell ◽

Hepatitis B ◽

Nk Cells ◽

Natural Killer ◽

Chronic Hepatitis B ◽

Nk Cell ◽

Viral Control ◽

Cell Functions

Immune modulatory therapies are widely believed to represent potential therapeutic strategies for chronic hepatitis B infection (CHB). Among the cellular targets for immune interventions, Natural Killer (NK) cells represent possible candidates because they have a key role in anti-viral control by producing cytokines and by exerting cytotoxic functions against virus-infected cells. However, in patients with chronic hepatitis B, NK cells have been described to be more pathogenic than protective with preserved cytolytic activity but with a poor capacity to produce anti-viral cytokines. In addition, NK cells can exert a regulatory activity and possibly suppress adaptive immune responses in the setting of persistent viral infections. Consequently, a potential drawback of NK-cell targeted modulatory interventions is that they can potentiate the suppressive NK cell effect on virus-specific T cells, which further causes impairment of exhausted anti-viral T cell functions. Thus, clinically useful NK-cell modulatory strategies should be not only suited to improve positive anti-viral NK cell functions but also to abrogate T cell suppression by NK cell-mediated T cell killing. This review outlines the main NK cell features with a particular focus on CHB infection. It describes different mechanisms involved in NK-T cell interplay as well as how NK cells can have positive anti-viral effector functions and negative suppressive effects on T cells activity. This review discusses how modulation of their balance can have potential therapeutic implications.

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