Glial Cells as Key Mediators in the Pathophysiology of Neurodegenerative Diseases

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This review is of general interest, based on a comprehensive illustration of the three glial cells and their neurodegenerative diseases. Because of their extensive and accurate presentation it is of potential interest for significant number of readers in the field. On the other hand, important aspects of this review need to be consider critically, especially in terms of various scientific aspects and of their presentation. The  language of the review is widely acceptable, however throughout the whole text many mistakes are present that need to be corrected. The presentation of the three glial cells need to be considered critically. For example, the heterogeneity of astrocytes  is  mentioned only once, with no interest for its relevance; their structure includes the body and branches (called also shafts), however with no interest for the thin leaflets necessary at pre-post synapses and other sites; their young and senescent structures are significantly different, and never considered. The presentation of the glial cells and their diseases are abundant, however most cases of the reported cells and events have been chosen for the last decade or more. Recent developments,  innovative with respect to previous opinions, are often left out. Finally, the presented list of neurodegenerative diseases include also the MS, defined here "an autoimmune disorder of the CNS". I recommend to leave it out of this review.  In case the authors prefer to keep it included, I would prefer to reduce its size including only the similarities with the other diseases and moving it at the end of the disease list.  

 

 

Author Response

Comments 1: “For example, the heterogeneity of astrocytes  is  mentioned only once, with no interest for its relevance; their structure includes the body and branches (called also shafts), however with no interest for the thin leaflets necessary at pre-post synapses and other sites; their young and senescent structures are significantly different, and never considered.”
Response 1: Thank you very much for this comment. In the paragraph concerning astrocytes, a section introducing the division into two phenotypes, A1 and A2, has been added (line 125). Of course, the diversity in the morphology and function of astrocytes is not limited to this division. However, for the purposes of the following review, we have decided to limit ourselves to the aforementioned division.

Comments 2: “The presentation of the glial cells and their diseases are abundant, however most cases of the reported cells and events have been chosen for the last decade or more. Recent developments,  innovative with respect to previous opinions, are often left out.”
Response 2: The literature analyzed to create this review comes mainly from the last 10 years. This is a very broad topic, so only certain key aspects have been selected for the purposes of this article and its clarity. If the Reviewer believes that there are extra studies that should be included in this review, please let us know.

Comments 3: “Finally, the presented list of neurodegenerative diseases include also the MS, defined here "an autoimmune disorder of the CNS". I recommend to leave it out of this review.  In case the authors prefer to keep it included, I would prefer to reduce its size including only the similarities with the other diseases and moving it at the end of the disease list.”
Response 3: In accordance with the Reviewer's recommendation, the term “an autoimmune” has been removed.
We thank the Reviewer for this thoughtful comment. We agree that Multiple Sclerosis is traditionally classified as an autoimmune disease of the CNS. However, we deliberately chose to retain MS in this review because accumulating evidence over the last decade has fundamentally revised this view, identifying resident glial cells as key drivers of disease initiation, progression, and chronic neurodegeneration, independently of peripheral immune infiltration.
Recent single-cell, spatial transcriptomic, imaging and experimental studies demonstrate that chronic microglial activation, astrocyte-mediated BBB dysfunction, and oligodendrocyte/OPC failure represent central mechanisms shared between MS—particularly in its progressive forms—and classical neurodegenerative disorders such as AD, PD, ALS and HD. In this context, MS serves as a paradigmatic model of glia-driven neurodegeneration rather than an outlier.
As presented in the text, the role of glial cells is important  for the mechanisms of the development and maintenance of inflammation and neurodegeneration. We believe that this subsection does make the manuscript chapter more easy to follow.

Reviewer 2 Report

Comments and Suggestions for Authors

The manuscript provides a broad narrative overview of astrocytes, microglia, and oligodendrocyte lineage cells in major neurodegenerative disorders (AD, PD, MS, HD, ALS). However, in its current form the review requires major revision to improve factual precision, conceptual depth (especially regarding glial-state heterogeneity), and overall presentation/formatting quality. 

Major comments

1)

• The statement that glia “differ from neurons only by their inability to generate action potentials” is an overgeneralization and may be misleading; glia differ by lineage, excitability mechanisms, signaling modes, electrophysiological properties, and specialized functions beyond action potentials. Please rephrase more cautiously. 
• Microglial origin is simplified as “mesoderm… lineage of monocytes.” This should be corrected/updated (developmental origin and terminology), or at minimum rewritten more precisely and referenced appropriately. 

2)

The manuscript frequently uses dichotomies (e.g., M1/M2 microglia  and A1/A2 astrocytes  ). While historically common, these binaries can be oversimplified relative to current single-cell/spatial literature. The abstract explicitly mentions “glial heterogeneity” and omics-driven “dynamic shifts”  , but the body would benefit from a dedicated subsection that:

• summarizes major glial-state taxonomies (disease-associated microglia and disease-stage/state transitions),
• clarifies limitations of binary phenotypes,
• maps glial states to disease stage, region, and triggers (Aβ, α-syn, demyelination milieu, etc.).

3)

• Figure 1 and Figure 2caption includes “Created in BioRender. Marchesi, N. (2026) …” which is inconsistent with the manuscript year (2025) and looks like an error that must be corrected. 

4)

Add a high-yield summary table that links each disease to:

• dominant glial mechanisms (inflammation, synaptic pruning, BBB/vascular unit effects, myelin/OPC failure),
• representative molecular pathways/targets,
• evidence tier (human postmortem, imaging, animal models, iPSC, trials).

5)

In the Conclusions, the review moves toward therapeutic statements (e.g., microglial purinergic receptor P2X7R blockade; “limited side-effects”; “must not disturb neural network physiology”). These claims are currently too assertive for a general review conclusion and should be softened, qualified, and tied to evidence (preclinical vs clinical, known risks/limitations, off-target effects, BBB considerations, etc.). 

Minor comments (presentation, style, and technical fixes)

1. Language/grammar polishing is needed throughout (articles, punctuation, spacing around citations; occasional double punctuation such as “astrocytes,, ”). Example visible in AD section around BBB discussion. 
2. Consider consistent terminology and style:

• “Noteworthy” - “Notably” (more standard scientific tone). 
• Keep abbreviations consistent and defined once (the abbreviations list exists  , but also ensure first-use definitions in the main text).

1. Microglia paragraph: if retaining M1/M2, explicitly acknowledge it as a simplified heuristic and cite more recent state-based frameworks. 
2. Please ensure all placeholder template items are removed/filled (e.g., “Funding”, “Authors contribution”, etc.). 

 

Author Response

Comments 1a: “The statement that glia “differ from neurons only by their inability to generate action potentials” is an overgeneralization and may be misleading; glia differ by lineage, excitability mechanisms, signaling modes, electrophysiological properties, and specialized functions beyond action potentials. Please rephrase more cautiously.”
Response 1a: Thank you for pointing out this inaccuracy. The wide range of competences of glial cells is described in the following subsections, so we will omit this sentence here.

Comments 1b:“Microglial origin is simplified as “mesoderm… lineage of monocytes.” This should be corrected/updated (developmental origin and terminology), or at minimum rewritten more precisely and referenced appropriately.”
Response 1b: Thank you for pointing this out. We have clarified the origin of microglia with the following sentence: Most neuroglia is of ectodermal origin, with the exception of microglia, which is derived from the mesoderm ̶̶ specifically, the fetal macrophages that migrate into the neural tube during embryonic development [1] (line 42)

Comments 2a: “The manuscript frequently uses dichotomies (e.g., M1/M2 microglia  and A1/A2 astrocytes  ). While historically common, these binaries can be oversimplified relative to current single-cell/spatial literature.”
Response 2a: We thank the Reviewer for highlighting this important conceptual point. We fully agree that the traditional M1/M2 microglia and A1/A2 astrocyte dichotomies represent an oversimplification in light of recent single-cell and spatial transcriptomic studies, which have revealed a highly heterogeneous and dynamic spectrum of glial activation states.
In the revised manuscript, these binary classifications are used as simplified conceptual models to facilitate comparison across diseases, rather than as rigid or discrete biological states. We now explicitly acknowledge that in vivo glial phenotypes exist along a continuum and are shaped by regional, temporal, and disease-specific contexts (line 213)

Comments 2b: “The abstract explicitly mentions “glial heterogeneity” and omics-driven “dynamic shifts”  , but the body would benefit from a dedicated subsection that:

• summarizes major glial-state taxonomies (disease-associated microglia and disease-stage/state transitions),
• clarifies limitations of binary phenotypes,
• maps glial states to disease stage, region, and triggers (Aβ, α-syn, demyelination milieu, etc."

Response 2b: We understand that such a summary would be valuable for this review. However, we believe that Table 1 and Fiure 2 partially fulfils these needs. Therefore, in order not to lengthen the article itself, we have used the figure.

Comments 3: "Figure 1 and Figure 2 caption includes “Created in BioRender. Marchesi, N. (2026) …” which is inconsistent with the manuscript year (2025) and looks like an error that must be corrected." 
Response 3: Thank you for pointing out this error. Of course, the correct BioRender licence details have already been sent to the journal.

Comments 4: “Add a high-yield summary table that links each disease to:

• dominant glial mechanisms (inflammation, synaptic pruning, BBB/vascular unit effects, myelin/OPC failure),
• representative molecular pathways/targets,
• evidence tier (human postmortem, imaging, animal models, iPSC, trials)."

Response 4: Thank you for suggesting this idea. Such a summary will be perfect for this review. We hope that the table we have prepared meets your expectations.

Comments 5: “In the Conclusions, the review moves toward therapeutic statements (e.g., microglial purinergic receptor P2X7R blockade; “limited side-effects”; “must not disturb neural network physiology”). These claims are currently too assertive for a general review conclusion and should be softened, qualified, and tied to evidence (preclinical vs clinical, known risks/limitations, off-target effects, BBB considerations, etc.)."
Response 5: Thank you for this comment. Indeed, the statements mentioned by Reviewer can be found too assertive for this general review that is not focused on the clinical and pharmacotherapeutical issues, so they have been removed from the manuscript.

"Minor comments
(presentation, style, and technical fixes)

Language/grammar polishing is needed throughout (articles, punctuation, spacing around citations; occasional double punctuation such as “astrocytes,, ”). Example visible in AD section around BBB discussion. 

Consider consistent terminology and style:

• “Noteworthy” - “Notably” (more standard scientific tone). 
• Keep abbreviations consistent and defined once (the abbreviations list exists  , but also ensure first-use definitions in the main text).

Microglia paragraph: if retaining M1/M2, explicitly acknowledge it as a simplified heuristic and cite more recent state-based frameworks. 

Please ensure all placeholder template items are removed/filled (e.g., “Funding”, “Authors contribution”, etc.).

Response: Thank you for all comments. It seems to us that we managed to eliminate and correct all the identified errors, also from a linguistic perspective. We have also added/removed all placeholder template items.

When it comes to naming microglia M1/M2, we have added an explanation (line 213).

 

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

The revised version of the paper is greatly improved,  therefore now it can be accepted for publication.

Reviewer 2 Report

Comments and Suggestions for Authors

After significant revisions to the manuscript, it now meets all the requirements for publication.