Review for 10.1186/s12876-025-04067-8 (2025)

Title: The role of m6A regulators mRNA expression in peripheral blood mononuclear cells in
chronic hepatitis B: A novel Diagnostic and prognostic indicator
Version: 4 Date: 20 Apr 2025
Reviewer's report:
I understand the authors' intention to propose m6A regulators primarily as biomarkers. If the
scope of their study is limited to biomarker utility, direct measurement of m6A modification
may not be essential. In that case, a more comprehensive discussion of the relevant literature
would be sufficient to support their claims.
Clarification on Opposing Expression Patterns of METTL3/METTL14 and ALKBH5
In the Discussion, the authors describe that "METTL3 expression varied significantly across
health and different stages of CHB progression… METTL3 and METTL14 showed decreasing
trends, while IGF2BP3 and ALKBH5 were elevated in non-LC CHB patients but decreased in
LC patients". This opposing trend warrants further discussion. While the complexity of m6A
regulation is acknowledged, a short discussion of potential mechanisms (e.g., compensatory
feedback between writers and erasers, or differences across immune cell subtypes) would
aid interpretation. Additionally, the authors could briefly mention whether similar nonlinear
trajectories have been reported in other chronic inflammatory contexts.
On the Correlation Between METTL3 and Inflammatory Markers
The authors report that "METTL3 expression in PBMCs was negatively correlated with NLR
(rs = -0.3013) and PLR (rs = -0.2674), and positively correlated with LMR (rs = 0.4355)"
. While these results are statistically significant, the correlation strengths are modest. This
should be more explicitly acknowledged as a limitation of inference based solely on mRNA
levels, especially given that m6A-mediated effects are often context-dependent and post-
transcriptionally regulated.
Interpreting Decreased METTL3 Expression in CHB Progression
The Discussion rightly emphasizes METTL3’s role in immunity: "METTL3-deficient cells
exhibit downregulation of immune response genes… the TBK1-METTL3 axis enhances type I
IFN responses". However, METTL3 is also known to support HBV replication by stabilizing
viral RNAs. This dual role may lead to interpretive ambiguity. The authors might briefly note
that METTL3’s role may be cell-type or context-specific, and that downregulation in PBMCs
during cirrhosis could reflect host immune exhaustion or compensatory adaptation, rather than
a protective mechanism.
Causality and Cross-Sectional Limitations
The manuscript appropriately acknowledges that "the retrospective design… precludes causal
inference… prospective cohorts will track METTL3 changes pre/post-antiviral therapy". This
is sufficient and appreciated.
Clarifying the Novelty of PBMC-based m6A Biomarker Strategy
The authors highlight that "PBMCs… reflect systemic immune responses critical to HBV
pathogenesis… dynamic m6A changes in PBMCs may precede tissue damage". They also
compare METTL3 with conventional liver markers, showing that "METTL3 AUC = 0.8198
was higher than ALT, AST, and GGT". To sharpen the positioning of this work, a short
summarizing sentence in the Introduction or Discussion (e.g., "Unlike prior studies focused on
hepatic tissues, this study investigates systemic m6A signatures in PBMCs as a non-invasive
biomarker platform") would help underscore the manuscript's translational relevance.