Dear Editor,
We read with great interest the recent publication by Tang et al. [
1], which investigates in depth the role of antibody-mediated natural killer (NK) cell in chronic hepatitis B (CHB) infection. By integrating the T-cell receptor-like antibody specific for the HBV core 18–27 peptide (cTCRL-Ab) system with single-cell RNA sequencing technology, the authors addressed a clinical paradox: although pegylated interferon alpha (Peg-IFNα) treatment led to a general downregulation of CD16 expression, a subpopulation of CX3CR1
+KLRC2
-CD16
hi NK cells with enhanced functionality was enriched. This study provides valuable insights into NK cell heterogeneity and immune remodeling during antiviral therapy, significantly advancing our understanding of these processes. While we greatly value the innovative methodology and the identification of this unique NK subpopulation, we believe that further exploration of specific aspects could enhance the translational impact of these findings.
First, the impairment of antibody-dependent cellular cytotoxicity (ADCC) should be re-examined in terms of immune remodeling rather than immune restoration. Tang et al. [
1] extend the established concept of NK-cell functional dichotomy [
2] by showing that ADCC is impaired in parallel with cytokine production, with CD16 downregulation being a key determinant of reduced ADCC activity. Notably, Peg-IFNα treatment is associated with a reduction in overall CD16 expression while concomitantly enriching a highly active CX3CR1
+ subset, indicating that effective immunotherapy may not reinstate a canonical ‘healthy’ baseline state. Instead, it may preferentially reshape the NK-cell compartment toward specialized, high-function subsets, even at the expense of broadly distributed CD16 expression. This framework has important implications for therapeutic design: because antibody-mediated effector functions are frequently impaired [
3] in CHB and treatment further lowers global CD16 levels, endogenous ADCC alone is unlikely to provide sufficient antiviral activity. Therefore, strategies incorporating engineered high-affinity antibodies, such as cTCRL-Ab (
Fig. 1), may be required to augment effector engagement. By coupling viral antigen recognition with these remodeled CX3CR1
+ NK-cell populations, such approaches could leverage Peg-IFNα-induced immune modulation while improving targeting efficiency, thereby integrating immune reshaping with precision-directed cytotoxicity.
Second, the clinical translation of these findings should incorporate the checkpoint constraint, particularly the contribution of NKG2A to non-response. Although the authors identify the CX3CR1
+ subset as the principal effector population, an important limitation is evident: in non-complete responders (NCR), even this CX3CR1
+ subset shows significantly increased
KLRC1 expression (encoding the inhibitory receptor NKG2A) relative to responders (Fig. 5F of the original article) [
1]. Interpreting these findings in the context of immune checkpoints underscores a clinically relevant constraint: persistent NKG2A upregulation in NCR suggests that cells with an activated phenotype may remain functionally attenuated by inhibitory signaling, consistent with reports that hepatitis B virus infection increases NKG2A/CD94 expression and impairs NK-cell antiviral activity [
4,
5]. Accordingly, Peg-IFNα-induced remodeling may be required yet insufficient to achieve the desired therapeutic outcome if NKG2A-mediated inhibition persists, indicating a potential resistance mechanism in non-responders. This interpretation is supported by animal studies showing that blockade of the NKG2A-HLA-E axis can restore NK cytotoxicity and facilitate viral clearance [
5]. In addition, increased expression of other inhibitory receptors (e.g., TIGIT) in CHB has been associated with functional exhaustion [
6], suggesting that a broader inhibitory network may further limit the antiviral efficacy of the expanded CX3CR1
+ effector compartment. Collectively, these observations provide mechanistic rationale for combination strategies, including pairing Peg-IFNα with NKG2A blockade (e.g., monalizumab) to relieve inhibitory constraint and enhance antiviral activity [
7].
Third, it is essential to distinguish causality from correlation in interpreting the observed immune recovery. This study shows that enrichment of the CX3CR1
+KLRC2
-CD16
hi subpopulation is closely associated with favorable therapeutic outcomes, including hepatitis B surface antigen clearance (Fig. 5D, 6B of the original article) [
1]. However, the cross-sectional nature of the current dataset does not resolve directionality or temporal ordering: it remains unclear whether expansion of this cytotoxic subpopulation contributes to viral clearance, or whether declining viral antigen burden permits recovery of this population. Although
in vitro functional assays were performed (Fig. 4G of the original article) [
1], additional studies incorporating longitudinal intrahepatic sampling and/or humanized animal models are needed to determine whether expansion of this subpopulation precedes reductions in virological markers.
In conclusion, the study by Tang et al. [
1] marks a milestone, shifting our focus from ‘global activation’ to ‘subpopulation-specific remodeling.’ To aid clarity, we provide a conceptual summary of our key points in Figure 1. The figure was created with BioRender, and a publication license has been obtained. Addressing the issues discussed above, particularly regarding causality and combination therapy strategies, is essential for translating these biological insights into a functional cure for CHB [
8].
FOOTNOTES
-
Authors’ contribution
LX found the question and wrote the draft. YW and GW revised the manuscript. All authors have approved the letter.
-
Conflicts of Interest
The authors declare that they have no competing interests related to this work.
Figure 1.Mechanisms of Peg-IFNα-induced NK cell remodeling and proposed combinatorial strategies targeting the NKG2A checkpoint in chronic hepatitis B. Peg-IFNα, pegylated interferon alpha; CHB, chronic hepatitis B; cTCRL-Ab, T-cell receptor-like antibody specific for the HBV core 18–27 peptide; NK, natural killer; ADCC, antibody-dependent cellular cytotoxicity; HBV, hepatitis B virus.
Abbreviations
antibody-dependent cellular cytotoxicity
T-cell receptor-like antibody specific for the HBV core 18–27 peptide
pegylated interferon alpha
REFERENCES
- 1. Tang L, Wang Y, Jin Z, Gu Y, Zeng Z, Song L, et al. Dissecting antibody-mediated natural killer cell effects reveals a cytotoxic CX3CR1+KLRC2-CD16hi subset linked to hepatitis B virus outcomes. Clin Mol Hepatol 2026;32:683-705.
- 2. Oliviero B, Varchetta S, Paudice E, Michelone G, Zaramella M, Mavilio D, et al. Natural killer cell functional dichotomy in chronic hepatitis B and chronic hepatitis C virus infections. Gastroenterology 2009;137:1151-1160.e7.
- 3. Bertoletti A, Ferrari C. Innate and adaptive immune responses in chronic hepatitis B virus infections: towards restoration of immune control of viral infection. Gut 2012;61:1754-1764.
- 4. Tjwa ET, van Oord GW, Hegmans JP, Janssen HL, Woltman AM. Viral load reduction improves activation and function of natural killer cells in patients with chronic hepatitis B. J Hepatol 2011;54:209-218.
- 5. Li F, Wei H, Wei H, Gao Y, Xu L, Yin W, et al. Blocking the natural killer cell inhibitory receptor NKG2A increases activity of human natural killer cells and clears hepatitis B virus infection in mice. Gastroenterology 2013;144:392-401.
- 6. Wang J, Hou H, Mao L, Wang F, Yu J, Luo Y, et al. TIGIT signaling pathway regulates natural killer cell function in chronic hepatitis B virus infection. Front Med (Lausanne) 2022;8:816474.
- 7. André P, Denis C, Soulas C, Bourbon-Caillet C, Lopez J, Arnoux T, et al. Anti-NKG2A mAb is a checkpoint inhibitor that promotes anti-tumor immunity by unleashing both T and NK cells. Cell 2018;175:1731-1743.e13.
- 8. Cornberg M, Lok AS, Terrault NA, Zoulim F; 2019 EASL-AASLD HBV Treatment Endpoints Conference Faculty. Guidance for design and endpoints of clinical trials in chronic hepatitis B - Report from the 2019 EASL-AASLD HBV Treatment Endpoints Conference. J Hepatol 2020;72:539-557.
Citations
Citations to this article as recorded by
- Correspondence to letter to the editor on “Dissecting antibody-mediated natural killer cell effects reveals a cytotoxic CX3CR1+KLRC2-CD16hi subset linked to hepatitis B virus outcomes”
Zihan Jin, Libo Tang, Yuhao Wang, Shihong Zhong, Yongyin Li
Clinical and Molecular Hepatology.2026; 32(3): e427. CrossRef
