Review Reports

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This is an interesting review of IGFBP-2 in critical illness, COVID-19 and other conditions. It provides a useful overview of the topic and may be of value to researchers new to this area, or looking for new biomarkers in these conditions. There are two areas where further attention by the authors might improve this work: (1) some sections tend to “jump around” between diseases, and might benefit from better organization, and (2) some of the reference citations seem careless, with papers quoted incorrectly or inaccurately. Some of these are listed in the specific comments below, but it is suggested that the authors carefully check all references for accuracy.

 

Specific comments.

 

1. Abstract, line 21. “Beyond its role in endocrine disruption …”. I suggest using a term other than “endocrine disruption”, perhaps endocrine regulation or endocrine systems, since “endocrine disruption” has a specific meaning generally referring to the actions of exogenous chemicals on the endocrine system.

 

2. Line 42. The cited reference [2] provides no information about ALS. A reference should be added to document the decline in ALS levels.

 

3. Figure 1 has a significant error, as it shows two IGFBP molecules interacting with one IGF-1. This should be corrected for all six IGFBPs, to show a single IGFBP molecule binding a single IGF-1. This 1:1 ratio has been clearly documented.

 

4. Line 92. The cited reference [3] does not refer to a relationship between IGFBP-1 levels and mortality. Perhaps the authors could refer to Mesotten et al (DOI: 10.1210/jc.2002-020664) which specifically discusses this.

 

5. Lines 94-95. “ … which alters the distribution of IGF complexes …”. This would make more sense if the authors change it to the following: “ … which, together with the fall in IGFBP-3, alters the distribution of IGF complexes …”.

 

6. Lines 98-100. “The IGFBP-3/IGFBP-5 ratio, therefore, has been proposed as a potential marker for disease severity in critically ill patients (Figure 2).” Figure 2 is about IGFBP-2, not IGFBP-3 or IGFBP-5, and makes no mention of this ratio. Furthermore, there does not seem to be any basis for this proposal. It is strongly suggested that the authors delete this sentence entirely, and refer to Figure 2 somewhere else in the text.

 

7. Line 137. It is suggested to move the citation of Ref. [24] to the end of line 135: “ …insulin resistance, lipolysis, and protein catabolism [24], …”. As written, it implies that ref. 24 suggests this role for IGFBP-2 (which it doesn’t). 

 

8. Line 201. Ref. [45] identified IGFBP-2 as a protein that discriminates between COVID and control subjects, but it doesn’t provide any evidence that IGFBP-2 “plays a significant role in the inflammatory response and disease progression in sepsis and COVID-19”. The authors should re-phrase this section so that it doesn’t overstate the findings.

Author Response

Re: Submission No 3256351

 

Reviewer #1

There are two areas where further attention by the authors might improve this work:

(1*) some sections tend to “jump around” between diseases, and might benefit from better organization

 

Thank you for the suggestion - the revised text has been re-organized and expanded

 

 

(2*) Some of the reference citations seem careless, with papers quoted incorrectly or inaccurately. Some of these are listed in the specific comments below, but it is suggested that the authors carefully check all references for accuracy.

 

This was noted and the references were checked. Where necessary they were changed/moved.

 

 

Specific comments.

[1]. Abstract, line 21. “Beyond its role in endocrine disruption …”. I suggest using a term other than “endocrine disruption”, perhaps endocrine regulation or endocrine systems, since “endocrine disruption” has a specific meaning generally referring to the actions of exogenous chemicals on the endocrine system.

 

Thank you for the pertinent suggestion. In the revised version of the manuscript we have changed to "regulation".

 

 

[2]. Line 42. The cited reference [2] provides no information about ALS. A reference should be added to document the decline in ALS levels.

 

Thank you for pinpointing this omission. A relevant reference by GV deBerghe has been added.

 

 

[3]. Figure 1 has a significant error, as it shows two IGFBP molecules interacting with one IGF-1. This should be corrected for all six IGFBPs, to show a single IGFBP molecule binding a single IGF-1. This 1:1 ratio has been clearly documented.

 

The reviewer is absolutely right. The figure has been appropriately corrected in the revised version of the manuscript.

 

 

[4]. Line 92. The cited reference [3] does not refer to a relationship between IGFBP-1 levels and mortality. Perhaps the authors could refer to Mesotten et al (DOI: 10.1210/jc.2002-020664) which specifically discusses this.

 

Thank you for pointing this to us. In the revised version of the manuscript we have substituted this reference with the one suggested by the Reviewer.

 

 

[5]. Lines 94-95. “ … which alters the distribution of IGF complexes …”. This would make more sense if the authors change it to the following: “ … which, together with the fall in IGFBP-3, alters the distribution of IGF complexes …”.

 

This was changed per the Reviewer's suggestion in the revised version of the manuscript.

 

 

[6]. Lines 98-100. “The IGFBP-3/IGFBP-5 ratio, therefore, has been proposed as a potential marker for disease severity in critically ill patients (Figure 2).” Figure 2 is about IGFBP-2, not IGFBP-3 or IGFBP-5, and makes no mention of this ratio. Furthermore, there does not seem to be any basis for this proposal. It is strongly suggested that the authors delete this sentence entirely, and refer to Figure 2 somewhere else in the text.

 

In the revised version of the manuscript we have deleted this sentence and moved the reference to Figure 2 in part 3 of the main text

 

 

[7]. Line 137. It is suggested to move the citation of Ref. [24] to the end of line 135: “ …insulin resistance, lipolysis, and protein catabolism [24], …”. As written, it implies that ref. 24 suggests this role for IGFBP-2 (which it doesn’t).

 

In the revised version of the manuscript we have moved the citation to this reference as suggested.

 

 

[8]. Line 201. Ref. [45] identified IGFBP-2 as a protein that discriminates between COVID and control subjects, but it doesn’t provide any evidence that IGFBP-2 “plays a significant role in the inflammatory response and disease progression in sepsis and COVID-19”. The authors should re-phrase this section so that it doesn’t overstate the findings.

 

We thank the Reviewer for pointing this to us. In the revised version of the manuscript we have changed this sentence to "Interestingly, IGFBP-2 was shown to discriminate patients with COVID-19 from healthy subjects, serving as controls".

 

 

Reviewer 2 Report

Comments and Suggestions for Authors

Very interesting narrative review that needs to be more precisely related. Some suggestions are listed below.

 

General comments

Authors should develop molecular aspects explaining:

- IGFBP-2 function: what is the role of NLS sequence? RGD sequence?

- Endogenous and exogeneous factors increasing IGFBP-2 levels

- Association between increased levels of IGFBP-2 and IGFBP-3 limited proteolysis in cancer

 

Authors have completely omitted to present all the post-translational regulations concerning the IGF/IGFBP-2/IGFBPs system, which are nonetheless essential.

 

It is contradictory to present IGFBP-2 as a tumor suppressor (lines 239-240), and as an oncogene (line 145): authors should develop the reasons of the contradiction.

As the review is essentially observational reporting studies showing IGFBP-2 levels in circulation related to severity of various diseases, authors should focus and present this aspect systematically, and restrict their review on IGFBP-2 as a biomarker of severity of critical illness.

 

IGFBP-2 possibly used as a novel biomarker in some pathologies is correctly presented with right references cited. Conversely, it isn’t the case for IGFBP-2 as a therapeutic target as authors’ position on the roles of IGFBP-2 in pathogenesis isn’t convincing. Elevated IGFBP-2 could be a path to counter-act cell proliferation, inflammation, angiogenesis, etc. Thus, IGFBP-2 doesn’t play a functional role in pathogenesis but is a biomarker. Authors should modify the manuscript accordingly.

 

Authors should distinguish data and hypotheses whether the matter is on circulating IGFBPs or on extracellular environment

 

 

Specific comments

 Covid-19 is a minor part of the review that should not figure in the title causing confusion

 

Figure 1: it’s not clear why authors represent 2 molecules of IGFBPs for one IGF1. Authors should provide references

 

Lines 145-146 : IGFBP-2 isn’t an oncogene as the strict definition. Authors may change the sentence as “…where it may act as an oncogene in certain context…”

 

Lines 153-162: Authors should add the relation between limited proteolysis of IGFBP-3 (the main IGFBP in circulation) and increased levels of IGFBP-2

 

Lines 160-162: authors should cite studies reporting IGFBP-2 and IGFBP-3 relative affinity for IGF-1 and IGF-2 to possibly claim that IGFBP-2 binds to IGFs when the total IGFs exceed IGFBP-3 binding capacity

 

Lines 200-201: association between high levels of IGFBP-2 with the inflammatory response and disease progression in sepsis and COVID-19 doesn’t prove it plays a “significant role”: authors should either change the sentence or add functional data and references

Lines 236: same comment

 

Lines 237-239: Authors should cite right original references of studies proving the functionality of IGFBP-2 per se.

 

Line 244: IGFBP-2 activity: dependent or not dependent to IGF binding?

 

Lines 243-250: The paragraph isn’t precise enough, authors should provide precise explanation for “IGFBP-2 activity”, “IGFBP-2 could also play a role in future therapeutic strategies”, “ the therapeutic implications of IGFBP-2 in various diseases”

 

Line 260: Ref 35 is certainly not correctly cited

 

Ref 30: What is the originality of the present review compared to this one and maybe others dedicated to IGFBPs/IGFBP-2?

Author Response

Re: Submission No 3256351

 

Reviewer #2

Very interesting narrative review that needs to be more precisely related. Some suggestions are listed below.

General comments

Authors should develop molecular aspects explaining:

[1]. IGFBP-2 function: what is the role of NLS sequence? RGD sequence?

 

We thank the Reviewer for the suggestion. This has been added in the revised section 3. of the manuscript

 

 

[2]. Endogenous and exogeneous factors increasing IGFBP-2 levels

 

We thank the Reviewer for the suggestion. This also has been added in the revised section 3. of the manuscript

 

 

[3]. Association between increased levels of IGFBP-2 and IGFBP-3 limited proteolysis in cancer

 

We thank the Reviewer for the suggestion. This also has been added in the revised section 3. of the manuscript

 

 

[4]. Authors have completely omitted to present all the post-translational regulations concerning the IGF/IGFBP-2/IGFBPs system, which are nonetheless essential.

 

We thank the Reviewer for pinpointing this omission and for the suggestion. This has been added in the revised section 3. of the manuscript

 

 

[5]. It is contradictory to present IGFBP-2 as a tumor suppressor (lines 239-240), and as an oncogene (line 145): authors should develop the reasons of the contradiction.

 

We thank the Reviewer for the suggestion. This has been developed in the revised section 3. of the manuscript

 

 

[6]. As the review is essentially observational reporting studies showing IGFBP-2 levels in circulation related to severity of various diseases, authors should focus and present this aspect systematically, and restrict their review on IGFBP-2 as a biomarker of severity of critical illness.

IGFBP-2 possibly used as a novel biomarker in some pathologies is correctly presented with right references cited. Conversely, it isn’t the case for IGFBP-2 as a therapeutic target as authors’ position on the roles of IGFBP-2 in pathogenesis isn’t convincing. Elevated IGFBP-2 could be a path to counter-act cell proliferation, inflammation, angiogenesis, etc. Thus, IGFBP-2 doesn’t play a functional role in pathogenesis but is a biomarker. Authors should modify the manuscript accordingly. Authors should distinguish data and hypotheses whether the matter is on circulating IGFBPs or on extracellular environment

 

We thank the Reviewer for the pertinent suggestion. In the revised version of the manuscript the section on IGFBP2 as a therpeutic target has been eliminated. Moreover, in the revised text we focused on data rather than on hypotheses.

 

 

Specific comments

[7]. Covid-19 is a minor part of the review that should not figure in the title causing confusion

 

In the revised version of the manuscript the title has been changed, also taking into account a comment from the Journal's Editors.

 

 

[8]. Figure 1: it’s not clear why authors represent 2 molecules of IGFBPs for one IGF1. Authors should provide references

 

The Reviewer is absolutely right - this was an error and it has been corrected in the revised version of the manuscript.

 

 

[9]. Lines 145-146 : IGFBP-2 isn’t an oncogene as the strict definition. Authors may change the sentence as “…where it may act as an oncogene in certain context…”

 

This was accordingly changed in the revised section 3 of the manuscript.

 

 

[10]. Lines 153-162: Authors should add the relation between limited proteolysis of IGFBP-3 (the main IGFBP in circulation) and increased levels of IGFBP-2

 

This can be found in the revised section 3 of the manuscript.

 

 

[11]. Lines 160-162: authors should cite studies reporting IGFBP-2 and IGFBP-3 relative affinity for IGF-1 and IGF-2 to possibly claim that IGFBP-2 binds to IGFs when the total IGFs exceed IGFBP-3 binding capacity

 

References from the relevant literature have been added supporting this.

 

[12]. Lines 200-201: association between high levels of IGFBP-2 with the inflammatory response and disease progression in sepsis and COVID-19 doesn’t prove it plays a “significant role”: authors should either change the sentence or add functional data and references & Lines 236: same comment

 

This was corrected in the revised section 6 of the manuscript

 

 

[13]. Lines 237-239: Authors should cite right original references of studies proving the functionality of IGFBP-2 per se.

 

References from the literature were cited in the revised version of the manuscript

 

 

[14]. Line 244: IGFBP-2 activity: dependent or not dependent to IGF binding?

 

This theme was presented in the section on therapeutic potential of IGFBP2 and has been eliminated in the revised version of the manuscript.

 

 

[15]. Lines 243-250: The paragraph isn’t precise enough, authors should provide precise explanation for “IGFBP-2 activity”, “IGFBP-2 could also play a role in future therapeutic strategies”, “ the therapeutic implications of IGFBP-2 in various diseases”

 

In the revised version of the manuscript the section on IGFBP2 as a therapeutic target has been eliminated.

 

 

[16]. Line 260: Ref 35 is certainly not correctly cited

 

The Reviewer is right - the reference has been changed

 

 

[17]. Ref 30: What is the originality of the present review compared to this one and maybe others dedicated to IGFBPs/IGFBP-2?

 

Our work add the - albeit scant - data on COVID-19. This is noted in the Conclusion of the revised manuscript.

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Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

Thank you for these revisions which have addressed the points I raised. No further comments.

Reviewer 2 Report

Comments and Suggestions for Authors

The paper is considerably improved in the present form.

One minor point on English : As IGFBP-2 (or IGFBP-3) are not living bodies, authors may write "affinity of IGFBP-2 for IGFs" or "IGFBP-2 affinity" instead of "IGFBP-2's affinity for IGFs" (line 126).

Same comment for lines 112, 120, 192, 209, 219 and maybe others