The Importance of Neutrophils in Osteoarthritis: Current Concepts and Therapeutic Perspectives

Round 1

Reviewer 1 Report

The present review assesses the implications of neutrophils in OA. The topic is relevant, but certain deficiencies identified in both content and form need to be addressed based on the specific recommendations below:

Authors should consider the template provided by the journal for better organization and clarity of the information presented.

Abbreviations are explained when they first appear in the abstract or main text and contribute to making the text easier to read and the information conveyed more efficiently. Once an abbreviation has been established and explained, it will be used throughout the entire manuscript (abstract- osteoarthritis should be OA, ROS and NET shouldn’t be used abbreviated since they are used only one time in the abstract), with the exception of the abstract, where it must be treated separately. Please revise the whole manuscript in terms of abbreviations.

The conclusion part of the abstract should be improved in terms of outcomes and what future research directions this research may refer to.

The introduction section is poorly addressed. It is necessary to present a brief classification of the types of arthritis, each with its own particularities and also a briefly mention of the management of OA in terms of adjuvant therapies, conventional therapies and rehabilitative therapies. I suggest checking and referring to: PMID: 35454333.

The aim of the paper should be improved from the perspective of describing the contribution to the field under analysis and the elements of scientific novelty presented, especially since it is not the first manuscript evaluating these aspects.

There is no need for blank spaces between paragraphs.

The entire pathophysiological mechanism of OA should be included in a figure.

It would be advisable to introduce in treatment strategies targeting neutrophils the concept of nanomedicine already successfully used on various models studied and which may be promising for the management of rheumatic pathologies. I suggest checking and referring to: PMID: 37031724

The different treatment strategies targeting neutrophils should be depicted in a figure for better clarity.

The conclusions section should be improved with proposals to address the unmet needs identified in the implications of neutrophils in OA and future research directions should be developed.

Author Response

We would like to thank the reviewers and editors for their careful assessment of our manuscript and constructive comments. We have adjusted the paper accordingly. We believe the manuscript improved substantially.  

Authors should consider the template provided by the journal for better organization and clarity of the information presented.

Your feedback is greatly appreciated. We acknowledge the importance of adhering to the journal's specific template for consistency and ease of reading. Upon reviewing your comment, we realized that there might be some confusion regarding the template we used. To clarify, we did utilize a specific template for our manuscript, here is the link:

(https://www.mdpi.com/journal/immuno/instructions)

We would be grateful if you could assist us for this matter.

Abbreviations are explained when they first appear in the abstract or main text and contribute to making the text easier to read and the information conveyed more efficiently. Once an abbreviation has been established and explained, it will be used throughout the entire manuscript (abstract- osteoarthritis should be OA, ROS and NET shouldn’t be used abbreviated since they are used only one time in the abstract), with the exception of the abstract, where it must be treated separately. Please revise the whole manuscript in terms of abbreviations.

Thank you for your valuable feedback on our manuscript. We appreciate your guidance regarding the use of abbreviations and their appropriate handling throughout the manuscript. As per your suggestion, we revised the entire manuscript to ensure that abbreviations are appropriately introduced and consistently used after their initial explanation.

The conclusion part of the abstract should be improved in terms of outcomes and what future research directions this research may refer to.

Thank you for bringing this to our attention, and we  made the necessary revisions accordingly.

“Since neutrophils play a complex role in the pathophysiology of osteoarthritis, contributing to joint degradation as well as joint repair, targeting these cells is likely to pave the way for a potential therapeutic approach for the management of OA. Future studies are needed to investigate the use of targeted therapies to modulate neutrophil function and identify their subpopulations that are associated with osteoarthritis progression or response to treatment.”

The introduction section is poorly addressed. It is necessary to present a brief classification of the types of arthritis, each with its own particularities and also a briefly mention of the management of OA in terms of adjuvant therapies, conventional therapies and rehabilitative therapies. I suggest checking and referring to: PMID: 35454333.

Thank you for your feedback. We have included a brief mention of the management of OA.

“ Part 1:      OA is the most common form of arthritis. Several other types of arthritis with different etiologies including autoimmune processes (rheumatoid arthritis, psoriatic arthritis, ankylosing spondylitis, juvenile idiopathic arthritis, psoriasis), crystal deposition (gout), and infections (Lyme's arthritis, septic arthritis), have been described [1, 2]. OA is a musculoskeletal disease that differs from osteoporosis in that its pathogenic process involves the degradation of articular cartilage in a diseased joint and compromises periarticular structures [3]. It is a painful chronic degenerative disease that causes limited movement, bone remodeling, and osteophyte formation, leading to the deterioration of joint function.

Part 2: Despite recent advancements, a definitive treatment for OA remains challenging due to its complexity of pathophysiology. Numerous therapeutic strategies are recommended, including: 1. conventional drug therapy for pain relief and inflammation reduction; 2. biological surgical procedures such as transplantation of mesenchymal stem cells (MSCs); and 3. rehabilitation treatments that contribute to the improvement of patients' functionality and quality of life.”

The aim of the paper should be improved from the perspective of describing the contribution to the field under analysis and the elements of scientific novelty presented, especially since it is not the first manuscript evaluating these aspects.

Thank you for your comments on the draft. We appreciate your suggestions and have carefully considered them. We made some changes, and it was no longer continuous text; we did not include it in the comment section.

There is no need for blank spaces between paragraphs.

Thank you for reviewing our manuscript and providing your feedback. We appreciate your guidance regarding the formatting of paragraphs. In response to your feedback, we revised the manuscript to remove the blank spaces between paragraphs.

The entire pathophysiological mechanism of OA should be included in a figure.

We appreciate your suggestion to include the  pathophysiological mechanism of OA in a figure. We agree that a visual representation can greatly enhance the understanding of the complex processes involved in OA development. Based on your recommendation, we incorporated the figure in the revised version of the manuscript.

It would be advisable to introduce in treatment strategies targeting neutrophils the concept of nanomedicine already successfully used on various models studied and which may be promising for the management of rheumatic pathologies. I suggest checking and referring to: PMID: 37031724

We appreciate your feedback, we tried to add some treatment strategies targeting neutrophils the concept of nanomedicine. 

The different treatment strategies targeting neutrophils should be depicted in a figure for better clarity.

Thank you for your valuable feedback regarding the depiction of different treatment strategies targeting neutrophils in our manuscript. We appreciate your suggestion to include a figure for better clarity and to complement the existing table. We hope that this addition will better support the information provided in the table and aid in the comprehension of our work.

The conclusions section should be improved with proposals to address the unmet needs identified in the implications of neutrophils in OA and future research directions should be developed.

We appreciate the reviewer's insightful comment, and we have taken them into consideration to improve the conclusions section accordingly.

“ A better understanding of the mechanisms by which neutrophils contribute to inflammation and cartilage degradation in OA, including investigating the role of inflammatory factors produced by neutrophils and signaling pathways, would allow for promising therapeutic strategies for osteoarthritis. Additionally, by developing targeted therapies that specifically modulate neutrophil activity in OA, such as novel drugs that specifically inhibit or enhance neutrophil activity, we can hope to improve outcomes for patients with this debilitating disease and ultimately find a cure for this condition.”

Author Response File: Author Response.docx

Reviewer 2 Report

The review addresses a topic that is not well-covered elsewhere in the literature.  It is comprehensive and thorough.  

Concerns: 

1. The review should focus on OA as a human clinical problem.  The introductory paragraph about OA in horses is awkward and does not fit and should be removed.  

2. There are several innacurrate statements that should corrected:

P3, line 86: Obesity is a risk factor since the extra strain on the joints over time may result in unnecessary tension and damage.  It is now understood that the primary negative effect of obesity is metabolic not weight.

P3, line 90: Based on abundant evidence, synovitis is widely accepted as a hallmark of OA.  Yes but not to the same extent as RA

P4, line 119:  Mediators of inflammation and oxidative stress conspire to damage chondrocyte function and viability by reprogramming them to undergo hypertrophic differentiation called early 'senescence' [2].  Chondrocyte hypertrophic differentiation is a normal maturation program of chondrocytes and is not senescence.

P8, line 272: OA was thought to result from articular cartilage wear and tear but new evidence suggests that subchondral bone disturbance and synovial inflammation can initiate and exacerbate the disease [60]. …True OA does not result from wear and tear but the point is that OA results from inappropriate activation of formerly stable articular chondrocytes, which acquire activities including matrix degradation that lead to cartilage loss.  Subchondral bone and synovial inflammation are part of that but so is activation of the chondrocytes themselves, as well as ligaments etc in the joint space. 

Overall, the authors should double check everything they say about OA mechanisms - that is the weakest part of the review.  

English very good, only minor word syntax needed occasionally but would benefit from review for English corrections

Author Response

We would like to thank the reviewers and editors for their careful assessment of our manuscript and constructive comments. We have adjusted the paper accordingly. We believe the manuscript improved substantially.  

The review should focus on OA as a human clinical problem.  The introductory paragraph about OA in horses is awkward and does not fit and should be removed. 

Thank you for your feedback on the manuscript. We appreciate your input and have carefully considered your suggestion to remove the introductory paragraph about osteoarthritis (OA) in horses. Wehave  removed that part from the manuscript.

There are several innacurrate statements that should corrected:

P3, line 86: Obesity is a risk factor since the extra strain on the joints over time may result in unnecessary tension and damage.  It is now understood that the primary negative effect of obesity is metabolic not weight.

Thank you for your feedback regarding the relationship between obesity and joint diseases. We appreciate your insights and would like to address your comment. In response to your suggestion, we have revised the manuscript to reflect this updated understanding. The following statement has been included:

“Furthermore, metabolic obesity-related factors can contribute to the progression of joint diseases. It is believed that the adipose tissue augments the accumulation of metabolites in the peripheral space of the joints, leading to cartilage break down.”

P3, line 90: Based on abundant evidence, synovitis is widely accepted as a hallmark of OA.  Yes but not to the same extent as RA.

Thank you for pointing out that you specifically mentioned synovitis as “ a characteristic feature ” of osteoarthritis.

 P4, line 119:  Mediators of inflammation and oxidative stress conspire to damage chondrocyte function and viability by reprogramming them to undergo hypertrophic differentiation called early 'senescence' [2].  Chondrocyte hypertrophic differentiation is a normal maturation program of chondrocytes and is not senescence.

Thank you for bringing this to our attention, and we made the necessary revisions accordingly.

 P8, line 272: OA was thought to result from articular cartilage wear and tear but new evidence suggests that subchondral bone disturbance and synovial inflammation can initiate and exacerbate the disease [60]. …True OA does not result from wear and tear but the point is that OA results from inappropriate activation of formerly stable articular chondrocytes, which acquire activities including matrix degradation that lead to cartilage loss.  Subchondral bone and synovial inflammation are part of that but so is activation of the chondrocytes themselves, as well as ligaments etc in the joint space. 

Thank you for pointing this out. We have incorporated your suggestion throughout the manuscript. However, because there are some experiments that suggest changes in the subchondral bone region may precede cartilage degeneration, we needed to first explain this statement. Then, we discussed the fact that the exact mechanism is still unclear, but there is a positive relationship between articular cartilage degradation and disorders affecting the synovium, ligaments, and subchondral bone.

“     OA is a “whole joint” malady, as articular cartilage degradation is positively related to synovium, ligament, and subchondral bone disorders [59]. OA is generally accompanied by substantial cellular alterations as well as the overexpression of inflammation-related factors in joint tissue, which have catabolic effects on chondrocytes. Subchondral bone differs from cartilage because it is highly vascularized, allowing significant tissue turnover and remod-eling to adapt to mechanical loads. Subchondral bone inflammation can cause the produc-tion of angiogenic factors and local MMPs, which are thought to promote cartilage degener-ation and osteophyte formation [60]. Although OA results from inappropriate activation of formerly stable articular chondrocytes, new evidence suggests that subchondral bone dis-turbance and synovial inflammation can initiate and exacerbate the disease [61]. In this re-gard, some researchers have shown that structural changes in the subchondral bone region may be a precursor to the degeneration of the cartilage. They pointed out that subchondral bone advancements in thickness, volume, and stiffness increase the load transfer to the ar-ticular cartilage, causing dysfunction of the cartilage. However, the precise mechanism be-hind the potential role of deficient subchondral bone in the deterioration of articular carti-lage or vice versa during the development of OA is mainly unclear. Due to the close contact between cartilage and bone, it is more likely that abnormalities in one tissue will affect the features and functions of the other joint elements throughout the onset and development of OA [62]. “

Overall, the authors should double check everything they say about OA mechanisms - that is the weakest part of the review.  

We appreciate your feedback, we tried to consider this issue.

 Comments on the Quality of English Language:

English very good, only minor word syntax needed occasionally but would benefit from review for English corrections.

Thank you for reviewing our manuscript. We appreciate your feedback and apologize for not mentioning that we had our manuscript edited by a native speaker. We understand the importance of ensuring language accuracy and clarity in academic writing, and we took the necessary steps to address this aspect. The editor we worked with is certified and has experience in editing manuscripts in our field of study.

Author Response File: Author Response.docx

Reviewer 3 Report

In the manuscript titled "The Importance of Neutrophils in Osteoarthritis: Current Concepts and Therapeutic Perspectives" by Mehrani et al., the authors summarized studies on the epidemiology, the biology of neutrophils, the involvement of neutrophils in the pathology of osteoarthritis, and possible therapeutic approaches for treating osteoarthritis by targeting neutrophils. The manuscript is well-written and appropriately organized. This reviewer has no specific concerns about this manuscript.

Author Response

Thank you for your thorough review of our manuscript titled. We sincerely appreciate your positive feedback and are glad to hear that you found the manuscript well-written and appropriately organized.

Round 2

Reviewer 1 Report

The authors have significantly improved the manuscript based on the suggestions received.