Insights from the Evolution of Coagulation: A New Perspective on Anti-Inflammatory Strategies in the ICU—Focus on the Contact Activation System

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The manuscript by Wang and Zhu presents a rich and well-referenced review that explores an important and timely topic: the role of the contact activation system (CAS) in inflammation and critical illness, framed through an evolutionary perspective. The authors make interesting connections between the origins of coagulation factors, innate immunity, and clinical applications, particularly in sepsis and extracorporeal therapies. The manuscript offers a solid foundation and could certainly be impactful once refined. At present, though, there are areas where the argument could be made clearer, the structure tightened, and the balance between scientific discussion and clinical speculation adjusted. Below are my main suggestions for revision.

Major Comments

The evolutionary framing is certainly a fresh angle, but it is not entirely clear what new insights this adds beyond existing reviews. I suggest clarifying this in the introduction: how does looking at FXII evolution guide therapeutic thinking? And in the conclusion, reiterate what this perspective uniquely adds in terms of translational relevance.

The idea that FXII inhibitors could revolutionize ICU care is exciting, but needs to be presented more cautiously. Most of these strategies are still in early stages. Consider including a table summarizing the current development status of CAS-targeting drugs: this would help ground the reader in what is experimental and what is nearing clinical use.

References 26 and 34 are duplicates (Moellmer et al., Blood, 2024). Please remove the duplication and adjust the numbering; Reference 68 is cited twice but refers to different content. This needs to be split and renumbered.

FXI is discussed mainly in the context of coagulation, but its role in inflammation and immune responses is increasingly recognized. A recent review (DOI: 10.1055/s-0043-1764469) covers this well. I recommend citing and incorporating this dimension, it would round out the discussion.

Section 3 mentions exotoxins like staphylocoagulase and gingipains, which is relevant. But I think the review would benefit from including bacterial membrane components, like LPS, lipoteichoic acid, and peptidoglycans, as potentials CAS activators. There is robust data supporting this, and it would help the reader understand how broader pathogen signals link to contact activation. Suggested references: doi: 10.1002/rth2.12217 and doi: 10.1016/j.bvth.2025.100091

Throughout the manuscript, terms like “contact system activation (CAS)”, “factor XII (FXII)” “neutrophil extracellular traps (NETs)” are written out in full multiple times. After first mention, please stick to the abbreviations. This will improve the flow and make the manuscript easier to read.

This review has a lot of potential and already brings together several important themes. With some restructuring and careful clarification, especially around FXI's broader roles, reference corrections, bacterial triggers of CAS, and more measured language on clinical application, it can become a highly valuable resource for researchers and clinicians working at the interface of hemostasis, immunity, and critical care.

Author Response

First, I sincerely apologize for submitting my revised manuscript on the very last day of the deadline. This was my first attempt at writing a review article in English and submitting to an international journal, and I felt quite overwhelmed. Prior to working with my supervisor (the corresponding author), I had little exposure to research. It was under his encouragement that I began writing this article and learning how to conduct experiments. I also regret that I did not check my email promptly and mistakenly flagged your email as spam. I understand that such actions may seem unforgivable to a reviewer, and I deeply regret my oversight.

Second, I am immensely grateful for your thorough review of my manuscript. Apart from my supervisor, no one has read my work with such care and attention to detail. You pointed out specific issues, such as duplicate references and inconsistencies in the use of full terms and abbreviations for technical terms. Your meticulous feedback has been a tremendous encouragement on my research journey. I carefully studied the three articles you recommended in your review comments, which significantly inspired my writing of this review. Previously, my understanding of the contact activation system was limited to its role in coagulation. Through these articles, I gained a broader perspective on its diverse functions. I have incorporated your suggestions and made corresponding revisions to the manuscript.

Additionally, upon revisiting my article after two months, I noticed that the logical flow was not as cohesive as it could be, and some sections were overly verbose and redundant. In the revised version, I have addressed these issues by tightening the narrative and removing unnecessary content.

I kindly request your time to review my revised manuscript and provide further feedback on any remaining shortcomings. Your insights would be invaluable in helping me improve this work.

Thank you once again for your time and expertise.

Comments 1:The evolutionary framing is certainly a fresh angle, but it is not entirely clear what new insights this adds beyond existing reviews. I suggest clarifying this in the introduction: how does looking at FXII evolution guide therapeutic thinking? And in the conclusion, reiterate what this perspective uniquely adds in terms of translational relevance.

Response 1: Thank you for pointing this out. I/We agree with this comment. Viewed through an evolutionary lens, this paper positions the contact activation system (CAS) as a sensor of non-self and explains its functions at the molecular level. In conclusion, we argue that the advent of CAS inhibitors has renewed attention to this pathway. By tuning CAS activity, it may be possible to achieve anticoagulation while simultaneously modulating inflammation.

Comments 2: The idea that FXII inhibitors could revolutionize ICU care is exciting, but needs to be presented more cautiously. Most of these strategies are still in early stages. Consider including a table summarizing the current development status of CAS-targeting drugs: this would help ground the reader in what is experimental and what is nearing clinical use.

Response 2: It’s been added.

Comments 3：References 26 and 34 are duplicates (Moellmer et al., Blood, 2024). Please remove the duplication and adjust the numbering; Reference 68 is cited twice but refers to different content. This needs to be split and renumbered.

Response 3：References 26 and 34 have been removed, and the duplicate no. 68 entries in the reference list have been corrected.

Comments 4：FXI is discussed mainly in the context of coagulation, but its role in inflammation and immune responses is increasingly recognized. A recent review (DOI: 10.1055/s-0043-1764469) covers this well. I recommend citing and incorporating this dimension, it would round out the discussion.

Response 4：It has been incorporated into the manuscript as reference 84.

Comments 5：Section 3 mentions exotoxins like staphylocoagulase and gingipains, which is relevant. But I think the review would benefit from including bacterial membrane components, like LPS, lipoteichoic acid, and peptidoglycans, as potentials CAS activators. There is robust data supporting this, and it would help the reader understand how broader pathogen signals link to contact activation. Suggested references: doi: 10.1002/rth2.12217 and doi: 10.1016/j.bvth.2025.100091

Response 5：It has been incorporated into the manuscript as reference 84.

Comments 6：Throughout the manuscript, terms like “contact system activation (CAS)”, “factor XII (FXII)” “neutrophil extracellular traps (NETs)” are written out in full multiple times. After first mention, please stick to the abbreviations. This will improve the flow and make the manuscript easier to read.

Response 6：It has been revised.

Reviewer 2 Report

Comments and Suggestions for Authors

Dear authors in the paper several key claims are over‑extrapolated from preclinical or disease‑specific contexts (HAE, COVID‑19) to the ICU/sepsis setting; some evolutionary assertions need tighter sourcing; and sections would benefit from a more balanced appraisal of conflicting data (especially NETs, clinical trial outcomes with FXI inhibitors, and the still‑nascent clinical evidence for FXII inhibitors beyond HAE).

1. Strength of evidence and clinical translatability are overstated

• The manuscript repeatedly implies clinical readiness for FXII inhibition in sepsis/ICU. In reality, human data for FXII inhibitors are essentially limited to HAE (e.g., garadacimab, Phase 3 VANGUARD and OLE; recent UK HTA/NICE recommendation); to date, there are no randomized trials in sepsis or ECMO. Please temper claims and clearly distinguish between preclinical and clinical No mention is reported in the paper about the failure of Garadacimab in the treatment of COVID-19 disease (Papi A, Stapleton RD, Shore PM, Bica MA, Chen Y, Larbig M, Welte T. Efficacy and Safety of Garadacimab in Combination with Standard of Care Treatment in Patients with Severe COVID-19). Lung. 2023 Apr;201(2):159-170. doi: 10.1007/s00408-023-00615-9. Epub 2023 Mar 31. PMID: 37000214; PMCID: PMC10064633. )
• ECMO sections rely on animal models (rabbit antisense depletion of FXII/FXI; rat FXII knockout), which are encouraging for thromboinflammation but remain preclinical. State this explicitly and avoid implying patient-level outcome data.
• For bradykinin blockade in COVID-19, the literature is heterogeneous: early mechanistic hypotheses and small studies suggested benefit, but results are mixed, and large programs waned as the pandemic evolved. (Berra S, Parolin D, Suffritti C, Folcia A, Zanichelli A, Gusso Let al. Patterns of C1-Inhibitor Plasma Levels and Kinin-Kallikrein System Activation in Relation to COVID-19 Severity. Life (Basel). 2024 Nov 21;14(12):1525. doi: 10.3390/life14121525. PMID: 39768234; PMCID: PMC11679851.)

 

2. Evolutionary assertions require tighter sourcing and nuance

• The paper attributes FXII loss in cetaceans primarily to deep-sea thrombotic pressure. Please anchor this in comparative genomics, demonstrating pseudogenization of F12 (and KLKB1) in cetaceans and loss in many birds; avoid causal overreach (environmental selection is plausible but multifactorial).
• The “soil hypothesis” is interesting; ensure it is supported with Blood Advances evidence and presented as a hypothesis rather than a fact.

3. NETs and contact activation: acknowledge conflicting data

• The review presents NETs as unidirectionally prothrombotic via FXII activation. While a large body of work supports NET-driven immunothrombosis, not all studies find intact NET lattices directly trigger coagulation (some suggest free DNA/histones, rather than NETs per se, are the dominant triggers). Recommend incorporating this nuance and citing both views.

Author Response

1. Summary
Comments 1:Strength of evidence and clinical translatability are overstated The manuscript repeatedly implies clinical readiness for FXII inhibition in sepsis/ICU. In reality, human data for FXII inhibitors are essentially limited to HAE (e.g., garadacimab, Phase 3 VANGUARD and OLE; recent UK HTA/NICE recommendation); to date, there are no randomized trials in sepsis or ECMO. Please temper claims and clearly distinguish between preclinical and clinical No mention is reported in the paper about the failure of Garadacimab in the treatment of COVID-19 disease (Papi A, Stapleton RD, Shore PM, Bica MA, Chen Y, Larbig M, Welte T. Efficacy and Safety of Garadacimab in Combination with Standard of Care Treatment in Patients with Severe COVID-19). Lung. 2023 Apr;201(2):159-170. doi: 10.1007/s00408-023-00615-9. Epub 2023 Mar 31. PMID: 37000214; PMCID: PMC10064633. ) ECMO sections rely on animal models (rabbit antisense depletion of FXII/FXI; rat FXII knockout), which are encouraging for thromboinflammation but remain preclinical. State this explicitly and avoid implying patient-level outcome data. For bradykinin blockade in COVID-19, the literature is heterogeneous: early mechanistic hypotheses and small studies suggested benefit, but results are mixed, and large programs waned as the pandemic evolved. (Berra S, Parolin D, Suffritti C, Folcia A, Zanichelli A, Gusso Let al. Patterns of C1-Inhibitor Plasma Levels and Kinin-Kallikrein System Activation in Relation to COVID-19 Severity. Life (Basel). 2024 Nov 21;14(12):1525. doi: 10.3390/life14121525. PMID: 39768234; PMCID: PMC11679851.)
Response 1: I have rewritten this section of the article. It emphasizes that Factor XII (FXII) has no human studies related to anticoagulation or anti-inflammatory effects. The anticoagulant effects of ECMO are also limited to animal studies. Literature indicating no benefit of garadacimab in treating COVID-19 has been incorporated into the article.
Comments 2: Evolutionary assertions require tighter sourcing and nuance The paper attributes FXII loss in cetaceans primarily to deep-sea thrombotic pressure. Please anchor this in comparative genomics, demonstrating pseudogenization of F12 (and KLKB1) in cetaceans and loss in many birds; avoid causal overreach (environmental selection is plausible but multifactorial). The “soil hypothesis” is interesting; ensure it is supported with Blood Advances evidence and presented as a hypothesis rather than a fact.
Response 2: The section on whales lacking the FXII factor has been rewritten. The soil hypothesis is merely my personal assumption, just my individual perspective, provided as an example to facilitate the discussion of the subsequent content.
Comments 3：NETs and contact activation: acknowledge conflicting data The review presents NETs as unidirectionally prothrombotic via FXII activation. While a large body of work supports NET-driven immunothrombosis, not all studies find intact NET lattices directly trigger coagulation (some suggest free DNA/histones, rather than NETs per se, are the dominant triggers). Recommend incorporating this nuance and citing both views.
Response 3：The direct triggering of coagulation by NETs lattices has been incorporated into the article.

Reviewer 3 Report

Comments and Suggestions for Authors

This is an important article for the medical field, but some changes must be made:

1. The title did not reflect the article's content
2. Subchapters 1.1 and 1.2 can be combined into a single chapter.
3. It is important to specify the incidence of sepsis.
4. What are the guidelines for sepsis in the ICU?
5. How many studies included CAS-KKS in sepsis treatment? Can it be applied to all patients? Is this treatment approved?
6. It is important to present here the study's results regarding these treatments applied to the patients and what the survival rate is in this situation
7. The relationship between sepsis-CAS-KKS is little described
8. The first seven pages of the article are a physiology lesson

9.  Therefore, this article must be reorganized

Author Response

Comments 1:The title did not reflect the article's content

Subchapters 1.1 and 1.2 can be combined into a single chapter.

It is important to specify the incidence of sepsis.

What are the guidelines for sepsis in the ICU?

How many studies included CAS-KKS in sepsis treatment? Can it be applied to all patients? Is this treatment approved?

It is important to present here the study's results regarding these treatments applied to the patients and what the survival rate is in this situation

The relationship between sepsis-CAS-KKS is little described

The first seven pages of the article are a physiology lesson

9. Therefore, this article must be reorganized

Response 1: The newly uploaded manuscript is a fully rewritten version. Sections 1.1 and 1.2 have been merged. This paper focuses on the potential mechanisms by which CAS contributes to the pathogenesis and treatment of sepsis; accordingly, we do not discuss sepsis epidemiology or guideline-based management. At present, concepts related to the CAS–KKS  have not been translated into clinical practice, as contact-system inhibitors have not yet entered the clinic.

Reviewer 4 Report

Comments and Suggestions for Authors

The authors have conducted a review and evaluation of the evolution of coagulation, with a particular focus on anti-inflammatory strategies within the ICU setting, emphasizing the role of the contact activation system. To enhance the manuscript, the following major revisions are recommended:

1. Please provide a comprehensive explanation of why FXII was chosen as the focal point. Discuss its specific significance in coagulation, contact system activation, and its potential therapeutic implications, especially in the context of inflammation and critical care.
2. The current detailed account of the coagulation cascade may be overly exhaustive and could potentially overwhelm or bore the reader. It is advisable to condense this section into a clear, concise overview that highlights key developments and concepts relevant to the contact activation system and inflammatory processes.
3. Include a detailed discussion on how coagulation pathways, particularly contact activation factors, influence COVID-19 pathophysiology. Address topics such as coagulopathy, thrombotic complications, and the interplay between inflammation and coagulation in COVID-19 patients.
4. The current title emphasizes the contact activation system's importance in ICU management, yet this aspect is insufficiently covered in the main text. Please add a new chapter explicitly titled "Role of the Contact Activation System in ICU Strategies" or similar, providing detailed information on how this system influences treatment approaches, patient outcomes, and potential therapeutic targets in the ICU setting.
5. To provide a comprehensive overview, add a few sentences exploring how other coagulation factors interact with or influence the contact activation system and inflammation, especially within critical illness contexts.

Author Response

Comments

1. Please provide a comprehensive explanation of why FXII was chosen as the focal point. Discuss its specific significance in coagulation, contact system activation, and its potential therapeutic implications, especially in the context of inflammation and critical care.
2. The current detailed account of the coagulation cascade may be overly exhaustive and could potentially overwhelm or bore the reader. It is advisable to condense this section into a clear, concise overview that highlights key developments and concepts relevant to the contact activation system and inflammatory processes.
3. Include a detailed discussion on how coagulation pathways, particularly contact activation factors, influence COVID-19 pathophysiology. Address topics such as coagulopathy, thrombotic complications, and the interplay between inflammation and coagulation in COVID-19 patients.
4. The current title emphasizes the contact activation system's importance in ICU management, yet this aspect is insufficiently covered in the main text. Please add a new chapter explicitly titled "Role of the Contact Activation System in ICU Strategies" or similar, providing detailed information on how this system influences treatment approaches, patient outcomes, and potential therapeutic targets in the ICU setting.
5. To provide a comprehensive overview, add a few sentences exploring how other coagulation factors interact with or influence the contact activation system and inflammation, especially within critical illness contexts.

 

Response

I have rewritten this review article. In the new version, the role of FXII factor in sepsis has been redescribed. The description of the coagulation cascade has been significantly reduced. The final paragraph of the first chapter explains that organ support in the ICU, artificial management of anticoagulation, and the entry of sepsis-related bacteria and their metabolic products into the bloodstream are the reasons why ICU physicians need to focus on the contact activation pathway.

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

Dear authors, several key claims in the second version of the paper are over-extrapolated from preclinical or disease-specific contexts (HAE, COVID-19) to the ICU/sepsis setting.

The narrative occasionally lacks logical progression. For example, the transition from evolutionary biology to ICU applications is abrupt.

The review summarizes existing studies but offers limited critical appraisal of conflicting evidence (e.g., inconsistent clinical outcomes of FXII inhibitors in COVID-19 and sepsis).

The authors should discuss the limitations of animal models and the translational gap more explicitly.

Comments on the Quality of English Language

Numerous grammatical errors and awkward phrasing reduce readability.

Some sentences are overly complex and need simplification for clarity.

Reviewer 3 Report

Comments and Suggestions for Authors

The article has been significantly improved and can be published  in the revised form

Reviewer 4 Report

Comments and Suggestions for Authors

The revised draft effictively addresses the comments. Thank you