The Effect of Probiotics on Intestinal Tight Junction Protein Expression in Animal  Models: A Meta-Analysis

Round 1

Reviewer 1 Report

The article has been improved in accoreance with reviewers' suggestions.

Author Response

Thanks for your review.

Reviewer 2 Report

The authors presented one very interesting and detailed study named “ The effect of probiotics on intestinal tight junction protein expression in animal models: a meta-analysis”. The analysis revealed significant impact of these probiotics in tight junction related proteins expression, such as  occludin, claudin, and  zonula occludens-1. The criteria to choose the articles included in these kind of analysis should be very clear, and rigorous. Regarding to this point, my only concern is the fact presented on table 1, related to TJP evaluation. There are at least three methodologies used : Western Blot, qRT-PCR, and Immunohistochemical analysis. In my opinion, Western blot and Imunohistochemical analysis indicates protein expression, and qRT-PCR indicates mRNA transcription. I Think this point should be discussed in the text.

Author Response

Thank you for your advice. We revised the manuscript as you commented. Please confirm the attachment.

Author Response File: Author Response.docx

Reviewer 3 Report

In this study, the authors analyzed the effects of probiotic administration on TJP expression, including occludin, claudin, and ZO-1, using meta-analysis. Their analysis data revealed that probiotics are effective in improving TJP expression in IBD animal model. It is well written, didactical and has methodologies.

I have some comments to improve the manuscript:

1. Introduction is insufficient.
2. The data are based on animal model, it is hard to apply it on the human body, are there any publications which supported their results in human IBD? The authors may discuss more in the discussion part.
3. Some writing mistakes:

Line 46: “increase” should be “increased”

              Line 231: “one the previous study” should be “one previous study”

               Line 271: ”be helpful at” should be “be helpful in”

               Line 272: “ad-ministration” should be “administration”

4. In the References, the citation numbers are duplicated.

               Line 310, reference 12, the review change is not accepted.

Author Response

Thank you for your comment. As you pointed, we revised the manuscript.

Please confirm the attachment.

Author Response File: Author Response.docx

This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.

Round 1

Reviewer 1 Report

The study is interesting. However, some points should be addressed before the manuscript can be considered for publication.

The main issue – Why do you call your study as describing “murine inflammatory bowel disease model” (L14) and “expression in the murine intestine”  (L227) when some studies listed in Table 1 were performed using rat (mostly), chicken, or rabbit as model animals?

Other comments:

L37 IBD abbreviation should be explained

L42-43 Please unify throughout the manuscript. In these line you describe ZO-1 (tight-junction-associated protein, which also known as Tight junction protein-1) as not being a tight junction protein (TJP). In the rest of the manuscript, you include ZO-1 as one of TJPs. Also please rephase the section “such as occludin, claudin, etc.” to “such as occludin, claudin, and others”, “which include, among others, occludin, claudin” or similar.

Please describe the tight junction proteins as TJP consistently.

L46 unfortunate wording, what do you mean by "improving IBD" ? Also please correct to “study [3]”

L50-53 The aim of this study should be formulated precisely, in different way. In your study you do not explore the relationship between two reports analyzing the expression of pro-inflammatory cytokines.

All symbols and abbreviation used in the tables should be explained int tables’ footnote. Also please write probiotic names in italic

Table 3. correct “ci” to “CI”.

L177 Crohn's disease

L187 “and” - Something is missing here.

L199-201 grammar

L269 correct to “tight”

Thank for the opportunity of reviewing this interesting work.

Author Response

Thanks for your comment on this article. Please see the attachment.

Author Response File: Author Response.docx

Reviewer 2 Report

The study is a meta-analysis that evaluated the effect of probiotics on the expression of tight juction proteins in an animal model. The theme is innovative and could support explanations about the mechanism of action of probiotics, thus supporting future studies with humans. However, the study has important weaknesses that need to be reviewed.

Abstract

Line 27 – I believe that the animal study is not a limitation. Please, remove this sentence.  Moreover, explore the strengths of your study .

Introduction

Line 32- The reference is incorrect. the authors who defined this concept and was cited by the reference used was Hill et al 2014. Please, correct it.

Line 38-45. Please rewrite this paragraph as the sentences are with repeated information and no connection to the next paragraph

Methods

Line 57- The authors describe that used PRISMA 2009. The current PRISMA is Page MJ, McKenzie JE, Bossuyt PM, Boutron I, Hoffmann TC, Mulrow CD, Shamseer L, Tetzlaff JM, Akl EA, Brennan SE, Chou R, Glanville J, Grimshaw JM, Hróbjartsson A, Lalu MM, Li T, Loder EW, Mayo-Wilson E, McDonald S, McGuinness LA, Stewart LA, Thomas J, Tricco AC, Welch VA, Whiting P, Moher D. The PRISMA 2020 statement: an updated guideline for systematic reporting reviews. BMJ. 2021 Mar 29; 372:n71.doi:10.1136/bmj.n71. PMID: 33782057; PMCID: PMC8005924. Please, update this.

Line 57 - According to the PRISMA checklist, the flowchart must be described and cited in the results. Please correct this.

Line 58 - The authors cited only the keywords used. According to the PRISMA checklist, the aurhors should present the full search strategies for all databases, registers and websites, including any filters and limits used.

Line 64- Was this selection performed by two reviewers independently? This must be described. What were the inclusion and exclusion criteria?

Fig 1 - The flowchart was not prepared as requested in PRISMA. It is necessary to describe the number of articles identified in each database, the number of duplicates excluded, the reason for the exclusion of articles in phase 2, among others. Please make the adjustment

- Acoording to PRISMA, the authors should “Specify the methods used to assess risk of bias in the included studies, including details of the tool(s) used, how many reviewers assessed each study and whether they worked independently, and if applicable, details of automation tools used in the process” and “Describe any methods used to assess risk of bias due to missing results in a synthesis (arising from reporting biases).” The authors described only the second request. They did not assess the risk of bias of the studies selected through questionnaires such as Joanna Briggs, Cochrane and others

Results

- It is recommended after the description of each result, to cite the references of the articles that presented that result

Table 1 - It is also recommended to describe in Table 1: treatment time, type of treatment for each group, form of probiotic administration (gavage, diet?), method used in the evaluation of protein expression. Also, tables do not have inner rows.

3.2 line107- When describing each result, please cite the SMD; 95%CI, Q, P and I2 in parentheses

Line 138 - Why did you include studies that used prebiotic or medicinal if the objective was to assess the effect of probiotics?

- Considering the high heterogeneity, why did you not conduct subgroup analysis for time of treatment, dose, type of administration, type of animal?

Line 161. The authors describe in this line that there is publication bias, but in the abstract it is described that there was no publication bias by the Eggers test. Which one is correct?

Discussion - It is recommended that the discussion begins with a summary of the results and that these results are compared with the literature and discussed in order to explain the results found. The first paragraph of the discussion of this article is more suitable for an introduction than for a discussion, as it is not related at any time to the results found. Studies are just cited.

Line 188 - this was not described in the results section

192-193 –Please, rewrite.  you can not conclude this with the results  that you described.

Line 198- I believe that the subgroup analysis would explain some of this high heterogeneity.

- Please describe strengths and limitations

- Conclusion is an answer to your objective. the purpose of this study was not to compare medicinal with probiotics. Please rewrite the conclusions.

Author Response

Thanks for your comment on this article. Please see the attachment.

Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

Line 45- Please, excluded "which, in conjunction with zonula occludens-1 (ZO-1), regulate adhesion among the cells and act as a biological barrier that moderates the movement of water and substances that pass through [11-12]"

Line 59;70: As already mentioned, Figure 1 should be cited and described only in the results section.

Line 69- The content described as exclusion and inclusion criteria, in fact is the description of how the election of studies in Phase 1 and 2 of the systematic review were made. Please rewrite this section.

What would be inclusion criterion? Studies with at least one groups using the Isolated Probiotic? any type of animal or just mice and rats? adults or animals in childhood? Have you excluded which types of paper?

Line 73 - According to the prism, the selection of papers should be done by two reviewers independently and not under discussion.

The authors did not present the evaluation of the Risk of Bias in the Included Studies, nor a justification for not presenting it. They also did not present the search strategy used in each database.

The subgroup analysis presented in Tables 2 and 3 were only for strain. The question in the first review was: Why did not do this analysis also for intervention time, dose as heterogeneity remained high with the subgroup analysis considering the strain.

It is not necessary to include this section: "If the Regression Model is not meantent (p> 0.05) in the Analysis Item, The Null Hypothesis Cannot Be Rejected, Whereas IF There is no Publication Bias, There is no Relationship Between the Effect size and Standard Error " The question made to the authors was not that. The question was: in the line 24 the authors described: "The Egger’s linear regression test detected no publication bias, " but in the line 180, the authors described the opposite: "It implies that there is a publication bias in these results"

Author Response

Dear reviewer,

Thank you for your fruitful advice.

I am happy that this article could be better through this correction.

We revised it, please check the attachment.

Best regards,

Sung-Il Ahn

Author Response File: Author Response.docx