Endocannabinoid System-Related Inflammation and Progression of Autosomal Dominant Polycystic Kidney Disease

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Summary

The authors present an interesting evaluation of endocannabinoid system activity and inflammatory status in patients with autosomal dominant polycystic kidney disease (ADPKD). Several significant variations between the analyzed parameters are reported, and the manuscript is generally well written. I have only a few minor concerns that should be addressed to further improve the clarity and scientific completeness of the work.

Abstract

The background section of the abstract (lines 13–17) is somewhat verbose and should be shortened to improve clarity and focus.

Introduction

This section would benefit from further development. In particular, the authors should mention the most relevant genes associated with the endocannabinoid system (e.g., FAAH2, FAAH1, CNR1) and their links with human disease. The following references may be useful for this purpose: (https://doi.org/10.1016/j.gene.2025.149703; https://doi.org/10.1002/ajmg.b.30693)

The PKD gene superfamily should also be briefly mentioned to provide better genetic context.

In addition, the OMIM entries associated with ADPKD caused by PKD1 (#173900) and PKD2 (#613095) should be explicitly reported.

Materials and Methods

Based on the participant group allocation described in the manuscript, the authors should clarify whether this study represents a randomized clinical trial or a prospective observational study.

If the study is a randomized clinical trial, the corresponding registration number should be explicitly reported.

Results

In Tables 2 and 3, the authors should clarify in the footnotes how the differences between the two groups were calculated.

The Results section would benefit from including a correlation plot to better illustrate the relationships among the analyzed parameters.

Figure 4: The authors should explain why a multiple linear regression model was presented instead of a conventional PCA plot, which could potentially provide a clearer summary of the overall data distribution.

Discussion

Although somewhat lengthy, the Discussion section is well written and effectively explains the possible biological reasons underlying the observed results.

Author Response

We thank the Reviewer for the careful evaluation of our manuscript and for the insightful comments that have helped us improve its quality. Our point-by-point responses are provided below.

Abstract - The introductory part of the summary (lines 13-17) has been modified and simplified. The text that is crossed out is intended for deletion. The new text sections are highlighted in blue.

Introduction

– The introduction was supplemented with the topic of the most important genes related to the endocannabinoid system. We would like to thank the reviewer for the suggested sources, they were used in the text - references no. 8 and 9. Lines were 59-71 added.

- The introduction has been supplemented with information about the PKD gene superfamily. Lines were 90-104 added.

- The introduction has been supplemented with OMIM entries related to ADPKD. Lines were 90-104 added.

Materials and Methods – We confirm that the study is a prospective observational study. This has now been clearly stated in the Methods section. Lines 149-151 added.

Results

- In Tables 2 and 3, footnotes explain how the difference between groups was calculated.

- In response to the Reviewer’s suggestion, we added a correlation heatmap summarizing the main associations among endocannabinoids, inflammatory markers, and renal function parameters in the ADPKD group. We also included selected scatter plots illustrating the most relevant correlations. Lines were 274-287 added.

-     Tables containing only statistically significant correlations were removed from the paper. The tables containing all correlations were retained in the supplementary materials.

 

Reviewer 2 Report

Comments and Suggestions for Authors

The manuscript addresses a relevant topic and explores a potentially interesting link between the endocannabinoid system, inflammation and ADPKD progression. However, several methodological and presentation issues need to be addressed:

1. The statistical analysis needs clarification. Please explain how variables were selected for the regression model, justify the use of stepwise regression and address multiple testing given the large number of correlations reported. If no correction for multiple comparisons was applied, this should be stated as a limitation.
2. The study is observational and cross-sectional, yet the manuscript repeatedly suggests mechanistic and therapeutic implications that are not demonstrated by the presented data. These statements should be toned down.
3. Recheck Table 5, as some values appear inconsistent. In the control group, a correlation coefficient of 0.01 is reported together with p = 0.000, which is unlikely and may reflect a reporting error.
4. The main findings are obscured by the volume of descriptive correlation data. The section should be streamlined and some tables could be moved to the Supplementary Material.
5. The Discussion should be shortened and centered on the study findings and their limitations. Several parts read like a broad narrative review rather than a discussion of the presented data.
6. The reference list should be checked carefully, as it contains several duplicate entries. For example, references 23 and 37, 26 and 52, 49 and 63, 50 and 64, 53 and 65, 62 and 68.

Author Response

We thank the Reviewer for the careful evaluation of our manuscript and for the insightful comments that have helped us improve its quality. Our point-by-point responses are provided below.

The text that is crossed out is intended for deletion. The new text sections are highlighted in blue.

1. We have clarified the statistical methodology in the revised manuscript. Variables included in the regression model were selected based on significant associations observed in univariate analyses (Spearman correlations). A stepwise approach was used to identify independent predictors. Lines 190-195 were added. We acknowledge that no correction for multiple comparisons was applied due to the exploratory nature of the study and the limited sample size. This has now been explicitly stated as a limitation in the Discussion section. Lines 482-486 were added.

 2.  As per the reviewer's comment, we refrained from suggesting mechanistic or therapeutic implications.

     Lines 481-483,492-494, and 510-511 were deleted.

 3. The results in Table 5 have been corrected.

 4. The results section has been simplified. Tables containing only statistically significant correlations were removed from the paper. The tables containing all correlations were retained in the supplementary materials. To improve the visualization of the relationships among the analyzed variables, we added a correlation heatmap summarizing the main associations among endocannabinoids, inflammatory markers, and renal function parameters in the ADPKD group. We also included selected scatter plots illustrating the most relevant correlations. Lines 274-287 were added.

     5.  Following a reviewer's comment, the "discussion" section has been simplified.

     6.The bibliography was checked and corrected.

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

The authors have adequately addressed all comments.