CD56^bright natural killer cells induce HBsAg reduction via cytolysis and cccDNA decay in long‐term entecavir‐treated patients switching to peginterferon alfa‐2a

Abstract

HBV surface antigen (HBsAg) reduction is well observed in chronic hepatitis B (CHB) patients treated with pegylated interferon alpha-2a (PegIFNα). However, the mechanism of HBsAg suppression has not been fully elucidated. Twenty-seven of 55 entecavir-treated CHB e antigen positive patients were switched to PegIFNα treatment (Group A) whereas 28 patients continued entecavir treatment (Group B). The percentage or absolute number of CD56 /CD56 NK cells, expression of receptors and cytokines were evaluated by flow cytometry for 48 weeks and correlated with treatment efficacy. In vitro, purified NK cells were co-cultured with HepAD38 cells for measurement of HBsAg, apoptosis and covalently closed circular DNA (cccDNA). In association with a reduction of HBsAg, the percentage and absolute number of CD56 NK cells was significantly elevated in patients in group A, especially in Virologic Responders (VRs, HBsAg decreased). Furthermore, the percentage of NKp30 , NKp46 , TRAIL , TNF-α and IFNγ CD56 NK cells were significantly expanded in Group A, which were positively correlated with the decline of HBsAg at week 48. In vitro, peripheral NK cells from Group A induced a decline of HBsAg in comparison with NK cells from Group B which was significantly inhibited by anti-TRAIL, anti-TNF-α and anti-IFNγ antibodies. Furthermore, apoptosis of HepAD38 cells and levels of cccDNA, were significantly reduced by TRAIL and TNF-α /IFNγ NK cells from Group A, respectively. A functional restoration of CD56 NK cells in entecavir-treated patients who were switched to PegIFNα contributes to HBsAg and cccDNA clearance through TRAIL-induced cytolysis and TNF-α/IFNγ-mediated noncytolytic pathways.

Combination of pegylated interferon-alpha and nucleos(t)ide analogue treatment enhances the activity of natural killer cells in nucleos(t)ide analogue experienced chronic hepatitis B patients

“…In patients with CHB, the cytotoxicity capacity of NK cells is retained but their ability to produce cytokines is reduced [22,23]. In our study, the proportion of CD56 bright NK cells in the combination treatment group was significantly higher than that in the NA group, which was consistent with the experimental results of another study [13]; by contrast, the proportion of CD56 dim NK cells was significantly lower than that in the NA group. We detected a reduction in lymphocyte counts after Peg-IFN-α treatment; however, the absolute number of CD56 bright NK cells still increased, which indicates that a decreased lymphocyte count does not affect NK cell activity.…”

Contribution of NK cells to HBsAg seroconversion in inactive HBsAg carriers following pegylated IFN therapy

“…18 CD56 bright NK cells induce HBsAg reduction via cytolysis and cccDNA decay in long-term entecavir-treated patients switching to PEG-IFN. 19 Combination therapy significantly influences NK cell phenotype and function. Differences between patients with CHB with HBsAg clearance and non-responders suggest that NK cells play a role in the clearance of HBsAg during IFN-based combination therapy.…”

The impact of currently licensed therapies on viral and immune responses in chronic hepatitis B: Considerations for future novel therapeutics

“…This has been further demonstrated where Peg‐IFNα add‐on was employed in patients virally suppressed with ETV, resulting in a reduction in T‐reg frequencies with an increase in NKG2C+ NK cells and TLR‐2+ CD14 monocytes, which was associated with treatment response . In the same cohort, the expansion of CD56 bright NK cells expressing activatory receptors NKp30 and NKp46 along with TRAIL and IFNγ correlated with HBsAg decline with potential cccDNA clearance through TRAIL‐induced cytolysis, demonstrating the importance of Peg‐IFNα for immune modulation and HBV clearance . Similarly, in patients primed with Peg‐IFNα prior to viral suppression, the maintenance of expanded functional CD56 bright NK cells has been shown to correlate with treatment response .…”

“…94 In the same cohort, the expansion of CD56 bright NK cells expressing activatory receptors NKp30 and NKp46 along with TRAIL and IFNγ correlated with HBsAg decline with potential cccDNA clearance through TRAILinduced cytolysis, demonstrating the importance of Peg-IFNα for immune modulation and HBV clearance. 95 Similarly, in patients primed with Peg-IFNα prior to viral suppression, the maintenance of expanded functional CD56 bright NK cells has been shown to correlate with treatment response. 27 It is noteworthy that the recovery of nonconventional T cells (iNKT and γδ T) was limited despite significant declines in HBsAg in a cohort of patients undergoing combination therapy.…”