Interleukin-38: A Candidate Biomarker for Disease Severity in Advanced Steatotic Liver Disease

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

  This study investigated serum levels of Il-38 in 3 types of patients, namely with alcoholic liver disease (ALD), metabolic dysfunction-associated liver disease (MASLD) and steatotic liver disease of mixed alcoholic and metabolic origin (MetALD). In cohort of 176 patients IL-38 was marker of disease severity as it correlated with MELD score and bilirubin level. 
 
 
I have some remarks that may be treated as limitations of this study
 
1.   Although common feature of investigated patients is fatty liver, the different etiologies make this cohort heterogenous. In consequence, the patients with MASLD had significantly greater BMI (probably with variable metabolic comorbidities) and patients with ALD more commonly presented liver failure. Moreover, ALD patients were not divided into those with and without alcoholic hepatitis, which is common decompensating factor.  
 
2.   IL-38 was correlated with AST that could result from alcoholic hepatitis, as AST in MASLD has another connotation. Association between AST and IL-38 should be explored more in-dept. 
 
3.   Authors claim that the study is prospective, but it only means that blood was taken for IL-38 in consecutively consulted patients, and it does not involve any follow-up of patients towards development of decompensation events or survival.  Any statements on predictive value of IL-38 should be avoided. The period covering the study should be given. 
 
4.   Decompensation encompasses several liver-related events like ascites, GI bleeding, icterus, encephalopathy, AKI and even HCC. It unknown how decompensation was defined in this study. 
 
5.   In majority of papers on IL-38 its concentration is given in pg/ml (in this study is expressed in ng/ml that provides values below 1).   

Author Response

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Reviewer 2 Report

Comments and Suggestions for Authors

This well-designed prospective monocentric cohort study investigates the role of interleukin-38 (IL-38) as a biomarker in steatotic liver disease (SLD), which includes metALD, ALD, and MASLD. The role of anti-inflammatory IL-1 family cytokines in advanced SLD and hepatic decompensation is a significant and understudied topic covered in this manuscript. The authors provide compelling evidence that IL-38 is elevated in decompensated disease and has a strong correlation with MELD score and disease severity. 

I have some comments:

1. According to the results : IL-38 more explicitly is a severity-associated or state biomarker, rather than a predictive or prognostic one.
2. The small number of healthy controls limits the interpretability of comparisons with disease groups (should be mentioned in the limitations)
3. The borderline significance in ALD/metALD vs healthy (p=0.046) should be interpreted cautiously.
4. Although etiological groups are included, the study is underpowered for robust subgroup analyses.
5. There was only one measurement of IL-38.It's unclear if IL-38 increases prior to, during, or following decompensation because it's a dynamic process.

 

Author Response

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Reviewer 3 Report

Comments and Suggestions for Authors

Reviewer comments:

In the present study, Wagner et al. aimed to characterize circulating IL-38 levels in a prospective cohort of patients with steatotic liver disease (SLD) and to evaluate their diagnostic and prognostic relevance, with the overarching goal of assessing IL-38 as a potential biomarker. This study is timely and relevant, as IL-38 remains relatively underexplored in the setting of advanced SLD, particularly given the growing emphasis on inflammatory pathways in MASLD/MASH and alcohol-related liver disease. Moreover, the proposed integration of IL-38 with the MELD score to improve the prediction of hepatic decompensation is of considerable clinical interest. Nevertheless, while the study addresses an important clinical question, several issues remain that require attention.

Major comments

• The title of the manuscript, “Interleukin-38 as a Mechanistic and Predictive Biomarker in Advanced Steatotic Liver Disease,” is somewhat misleading, as it refers to IL-38 as both a “mechanistic” and “predictive” biomarker. While the study supports its predictive value, showing higher IL-38 levels in patients with advanced steatotic liver disease, correlations with MELD score, and associations with laboratory markers of liver injury, it does not provide mechanistic evidence for IL-38’s role in SLD. Therefore, the title could be refined to emphasize its predictive or severity-related relevance rather than implying mechanistic insight.
• Only 8 healthy controls were included, which is too small to establish a robust baseline for IL-38 levels. This limits confidence in comparisons between SLD and "healthy" subjects.
• IL-38 alone demonstrated only moderate discriminatory performance for hepatic decompensation (AUC ~0.7), whereas excellent discrimination (AUC ~0.92) was achieved only when IL-38 was combined with the MELD score. Accordingly, the characterization of IL-38 as an independent predictive biomarker should be reconsidered. Instead, the authors should emphasize its additive or complementary value to established prognostic scores rather than implying standalone predictive capability.
• In the discussion section, the authors should more thoroughly contextualize the novelty of IL-38 by comparing its performance and relevance with other established biomarkers in advanced liver disease (e.g., IL-6). In addition, a more in-depth discussion of potential biological mechanisms is warranted. In particular, IL-38 has been proposed to counteract IL-1–driven inflammatory signaling (de Graaf DM, et al. Interleukin-38 in Health and Disease. Cytokine. 2022;152:155824), which is consistent with the systemic inflammation observed in hepatic decompensation. Finally, the authors should acknowledge the need for external validation in independent, multicenter cohorts to support the generalizability of their findings.

Author Response

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Round 2

Reviewer 3 Report

Comments and Suggestions for Authors

Minor changes:

- The title « Interleukin-38: A Candidate Biomarker of Disease Severity in Advanced Steatotic Liver Disease”, should be changed to “Interleukin-38: A Candidate Biomarker for Disease Severity in Advanced Steatotic Liver Disease”

- The manuscript would benefit from careful editing of the English language to improve clarity and readability. As an example, the sentence (line 294 of the last version) “Our association of IL-38 with advanced SLD severity is biologically plausible given its role as a counter-regulatory IL-1 family cytokine”, “our association” is awkward and unclear in English.

Author Response

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