PONE-D-20-12036

Plasma microRNAs biomarkers in mild cognitive impairment among patients with type 2 diabetes mellitus

PLOS ONE

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PLOS ONE

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Comments to the Author

1. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented. 

Reviewer #1: Yes

Reviewer #2: Yes

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2. Has the statistical analysis been performed appropriately and rigorously? 

Reviewer #1: Yes

Reviewer #2: Yes

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3. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: Yes

Reviewer #2: Yes

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4. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: Yes

Reviewer #2: Yes

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5. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: In this study, Iman I Salama et al reports that plasma expression of miR-132 was significantly higher in T2DM patients with MCI compared to those without MCI and to normal cognitive healthy subjects.

The cognitive impairment associated with diabetes is a world-wide problem. The article is meaningful because there are no reliable biomarkers for the patients of MCI with T2DM. However, there are several issues that need to be addressed.

1) In the study, the cognitive functions of normal cognitive healthy subjects and T2DM were assessed by the ACE III test, and the score less than 88 was diagnosed as MCI. Authors mentioned that the ACE III score of T2DM patients ranged from 69 to 100, however each score of T2DM groups with and without MCI was not shown. Authors should show the ACE III score of each group of T2DM patients as well as those of cognitive normal subjects.

2) How 163 participants were diagnosed as T2DM? Were they diagnosed by HbA1c and/or blood glucose level? The enrollment criteria of T2DM should be mentioned. In the paper, authors state that 32 of T2DM patients were taking insulin and the rest of patients (n=131) were taking oral hypoglycemic drugs (described in lines 153-154). However, the number of patients received treatments of insulin or oral hypoglycemic was 32 and 117, respectively as shown in Table 2. Please explain this discrepancy.

3) In the paper, the age, sex and education were matched between cognitive normal healthy subjects and T2DM patients (described in lines 82-83). Although the results of age and sex were mentioned in lines 150-152, authors have not shown whether the education level was matched. As shown in Table 2 and 3, the education level seems to be an important factor for the prediction of MCI. Thus, the comparison of education level between control and T2DM patients should be demonstrated.

4) Among the expression of miRNAs including miR-128, miR-132, miR-874, miR-134, miR-323 and miR-382, the expression of miR-132 was significantly higher in T2DM patients with MCI compared to those without MCI. Authors discuss the involvement of miR-128 and miR-874 in addition to miR-132, however there were no implications about the expression of miR-134, miR-323 and miR-382. Please discuss about these miR-134, miR-323 and miR-382 expressions.

5) Throughout the paper, there were many typographical errors such as “miRAs” in line 295. Please correct these wrong notations.

Reviewer #2: The manuscript PONE-D-20-12036 by Salama and colleagues explores the role of several plasma circulating miRNAs to assess their potential as a biomarkers of Mild Cognitive Impairment (MCI), among a population of Type 2 Diabetic patients. The authors focused on the analysis of previous miRNAs known to be associated with MCI. Their results show a significant correlation with high levels of circulating plasma miR-132 in T2D patients with MCI compared to patients without MCI or cognitive healthy individuals. Overall, the work presented by Salama and colleagues is of interest, well written and consistent. However, I recommend a few changes that would improve the quality of the manuscript.

Main points

1. The authors stated that total RNA extracted from plasma was measured with Nanodrop spectrophotometer. Could the authors indicate the amount of plasma RNA from plasma used for retro-transcription to perform miRNA detection? Also, I wonder if the authors were able to analyze the quality and concentration of small RNA by Bioanalyzer or by another alternative method.

2. While explaining the association with T2D with cognitive impairment the authors stated: “Hyperinsulinemia that precedes or accompanies T2DM increases concentrations of amyloid � through inhibiting its brain clearance.” (Line 211-212). Although a reader from the field will probably interpret this sentence easily, the authors might want to make this clear here by adding that amyloid � peptide is one of the main causes of neuronal death during of AD, which is known to be strongly associated with T2DM.

3. Finally, could the authors discuss the possible reason behind the increase in miR-132 in plasma and its potential source? This will maybe clarify the contradictory effect of high levels of miR-132 on MCI, since it is described in the literature that miR-132 exerts a number of beneficial neurolophysiological effects both in human and in mice.

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Reviewer #1: No

Reviewer #2: No

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Plasma microRNAs biomarkers in mild cognitive impairment among patients with type 2 diabetes mellitus

PONE-D-20-12036R1

Dear Dr. Salama,

We’re pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it meets all outstanding technical requirements.

Within one week, you’ll receive an e-mail detailing the required amendments. When these have been addressed, you’ll receive a formal acceptance letter and your manuscript will be scheduled for publication.

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Kind regards,

Stephen D. Ginsberg, Ph.D.

Section Editor

PLOS ONE

Comments to the Author

1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation.

Reviewer #1: All comments have been addressed

Reviewer #2: All comments have been addressed

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2. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: Yes

Reviewer #2: Yes

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3. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: Yes

Reviewer #2: I Don't Know

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4. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: Yes

Reviewer #2: Yes

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5. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: Yes

Reviewer #2: Yes

**********

6. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: (No Response)

Reviewer #2: (No Response)

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7. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files.

If you choose “no”, your identity will remain anonymous but your review may still be made public.

Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy.

Reviewer #1: No

Reviewer #2: No