Is IBS a Food Allergy? Confocal Laser Endomicroscopy Findings in Patients with IBS: A Narrative Review

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

1. "Allergy" must be separated into 5 categories in this manuscript: True IgE-mediated anaphylactic food allergy;  IgE-sensitized but eating; not IgE mediated but an intolerance perceived by the subject undergoing the procedure; IgE unknown but perceived as "allergic"; or no perception or intolerance and + on the confocal laser examination
2. What is the potential mechanisms of observed change in the mucosa when food is deposited and a change is observed?
3. is there a difference in food and confocal endomicroscopy in the duodenum vs ileum vs colon (same 
4.  Is it possible at this point to propose standards, location of deposition, in an suspected IBS case. etc

Author Response

R: ”Allergy" must be separated into 5 categories in this manuscript: True IgE-mediated anaphylactic food allergy;  IgE-sensitized but eating; not IgE mediated but an intolerance perceived by the subject undergoing the procedure; IgE unknown but perceived as "allergic"; or no perception or intolerance and + on the confocal laser examination

A: Thank you for pointing this out. Below, I will address your comments point by point:

True IgE-mediated anaphylactic food allergy:
We did not include any studies involving IgE in the context of patients with anaphylactic reactions to food. Allergic reactions to food are not necessarily related solely to the presence of IgE, but should be considered in a broader context that includes the presence of clinical symptoms, positive skin tests, etc. Therefore, we have revised the manuscript following your recommendations, focusing on the characteristics of the patients and the presence or absence of IgE positivity as outlined below:

To address the creation of the category "IgE-sensitized but eating", we have added a comment in the introduction section between lines 130 and 135:
“The sole use of specific IgE testing, although it is a quick and effective method for identifying allergic sensitization, is not recommended as it cannot confirm the presence of a clinical reaction to the allergen. Therefore, it is essential to distinguish between sensitization and true allergy, as some individuals with positive specific IgE may still tolerate the food. This distinction is crucial in order to prevent unnecessary dietary restrictions and the potential development of associated behavioral complications.”

“Not IgE-mediated but an intolerance perceived by the subject undergoing the procedure”:
In all the studies where a food challenge was performed, the selected patients tested negative on serological IgE tests. Nevertheless, they experienced an intolerance to the food, which Fritscher-Ravens defines as a "non-classical food allergy". We specify this in the passage at line 278 in the Results section:
“The group of Fritscher-Ravens and colleagues analyzed a pattern of mucosal changes via CLE, suggesting that these may represent non-classical forms of food allergy due to localized immune reactions in patients with negative IgE serological tests.”

IgE unknown but perceived as "allergic":
In all the studies analyzed, patients described with “atypical food allergy” were included based on the criterion of testing negative on serological IgE assays. Therefore, the IgE status was always known in these patients.

No perception or intolerance and positive on the confocal laser examination:
We addressed this particular aspect in line 343:
“Even 74% of GARF− patients displayed a local mucosal response with duodenal food challenge.”
These patients were also negative for IgE tests. The IgE status of healthy controls is not known in the other studies; however, no positive CLE reactions were observed in these subjects.

 

R: Is there a difference in food and confocal endomicroscopy in the duodenum vs ileum vs colon (same 

 

A: Thank you for pointing this out.

Food challenge studies have all focused on reactions of the duodenal mucosa. we have added a comment in the conclusion section between lines 497 and 500:
The mucosa of the ileum and colon has been analyzed in some studies investigating intestinal permeability in patients with inflammatory bowel disease (IBD), but without stimulation tests using food antigens. Only Grover analyzed the duodenum and jejunum, but without actual stimulation tests with food antigens.

 

R: What is the potential mechanisms of observed change in the mucosa when food is deposited and a change is observed?

 

A: Thank you for pointing this out. We have added a comment in the results section between lines 491 - 495  IELs, in a process partly mediated by the secretion of interferon-gamma (68) likely enhance epithelial permeability by activating myosin light chain kinase, leading to phosphorylation of myosin light chains within the contractile actomyosin ring of the tight junctions. This results in a redistribution of tight junction proteins such as occludin and claudins (69)

 

 

R: Is it possible at this point to propose standards, location of deposition, in an suspected IBS case. Etc

 

A: Thank you for pointing this out. We addressed this particular aspect in line 515 of conclusion section:

“Additionally, despite being a highly useful tool, CLE has significant challenges: it is expensive, technically demanding and requires prolonged sedation. CLE is also currently available only in a few specialized centers. These factors limit the generalizability and applicability of such studies in routine clinical practice”

Reviewer 2 Report

Comments and Suggestions for Authors

Paper: applsci-3504909: Is IBS a food allergy? Confocal laser endomicroscopy findings in patients with IBS: a narrative review

Dear Authors,

This narrative review presents recent findings on the application of confocal laser endomicroscopy for evaluating the intestinal barrier alterations in patients with food allergy and with IBS. This review underlined the contribution of CLE to both development of therapeutic strategies and to an improved understanding of the IBS pathophysiology.  The study is based on is based on about 72 publications and the organization of material is concise, the structure of the article being clear and logical.

Below you will find my brief thoughts on your manuscript.

My recommendations:

The research methodology:  In my opinion you must add the databases you used, number of references used, window of time.

Results presentation: There is only a single subtitle in the Results section, Mucosal Alterations and Food Allergy in IBS: Insights from Confocal Laser Endomicroscopy (line 159). I suggest to reorganize the Results section using more than one subtitle. The authors may present the results grouped on the intestinal segments, e.g., CLE results in small intestine segments of patients with food allergies and IBS; CLE results in colon of patients with food allergies and IBS.

In Table 1, the authors included papers cited as abstracts (ref. no 41, 42 and 43). In my opinion, if the authors have not access to the full version, the paper should not be taken into account as reference. On the other hand, references 44, 45 and 46, although they were included in the Results section, are not presented in Table 1.

Also, table 2 must be included and commented in the Results section, not in Discussions.

Both Table 1 and Table 2 must have titles and footnotes. Table 2 is included in the main manuscript, Table 1 is inserted at the end of the manuscript. Both tables must be inserted in the manuscript with respect to journal`s recommendation.

Overall structure of the manuscript is feasible for this type of paper. My recommendation is to accept after minor revisions.

Author Response

R: In my opinion you must add the databases you used, number of references used, window of time:

A: Thank you for pointing this out. we have added a comment in the matherial and methods section between lines 208 -216: To identify relevant studies for this review, a literature search was conducted using the PubMed database. Publication Date: Studies published up to January 2025. Out of 128 studies identified, 74 were included in this review were collected and 74 have been selected for this review.

 

R: Results presentation: There is only a single subtitle in the Results section, Mucosal Alterations and Food Allergy in IBS: Insights from Confocal Laser Endomicroscopy (line 159). I suggest to reorganize the Results section using more than one subtitle. The authors may present the results grouped on the intestinal segments, e.g., CLE results in small intestine segments of patients with food allergies and IBS; CLE results in colon of patients with food allergies and IBS.

A: Thank you for the comment. Food challenge studies have all focused on reactions of the duodenal mucosa. The mucosa of the ileum and colon has been analyzed in some studies investigating intestinal permeability in patients with inflammatory bowel disease (IBD), but without stimulation tests using food antigens. Only Grover analyzed the duodenum and jejunum, but without actual stimulation tests with food antigens. We have added a comment in the conclusion section between lines 497 and 500:
The mucosa of the ileum and colon has been analyzed in some studies investigating intestinal permeability in patients with inflammatory bowel disease (IBD), but without stimulation tests using food antigens. Only Grover analyzed the duodenum and jejunum, but without actual stimulation tests with food antigens.

R: In Table 1, the authors included papers cited as abstracts (ref. no 41, 42 and 43). In my opinion, if the authors have not access to the full version, the paper should not be taken into account as reference. On the other hand, references 44, 45 and 46, although they were included in the Results section, are not presented in Table 1.

A: We agree that full-text articles generally provide more comprehensive data and are preferable as references. However, we decided to include references 41, 42, and 43—despite being cited as abstracts—to provide a complete overview of the current state of the art regarding CLE and food antigen provocation tests. These abstracts represent preliminary but relevant findings in this rapidly evolving field, and we felt their inclusion was important to illustrate the breadth of available evidence, even if limited. Regarding references 44, 45, and 46, we would like to clarify that they are indeed included in Table 1.

AThank you again for your thoughtful feedback.

R: Also, table 2 must be included and commented in the Results section, not in Discussions. Both Table 1 and Table 2 must have titles and footnotes. Table 2 is included in the main manuscript, Table 1 is inserted at the end of the manuscript. Both tables must be inserted in the manuscript with respect to journal`s recommendation.

A: Thank you for your comment. We have moved the tables accordingly. Footnotes included.

Reviewer 3 Report

Comments and Suggestions for Authors

Comments are in the attachment.

Comments for author File: Comments.pdf

Author Response

R: The current abstract reads as a mix of the introduction and conclusion with a lot of details,

lacking focus on the review’s core contributions. Please rewrite it and make it clear and

brief

A: thank you for your comment, we modified the abstract following your suggestion.

 

R: suggest to add a diagram which explains CLE’s technical principles in the introduction

part. This will help readers grasp the methodology more effectively.

A: Thank you for pointing this out. We have added figure 1 the introduction section

R: Please check the reference format carefully. Now some includes DOIs, while others do

not.

A: Thank you for pointing this out. The following study do not have a doi: 32. 60. Doi added to: 41, 43, 71, 73