Binding Molecules in Tick Saliva for Targeting Host Cytokines, Chemokines, and Beyond

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The authors reviewed existing knowledge on tick salivary components that target host proteins involved in various aspects of defense that include hemostasis and immunity. The review focus on the mechanism of action and what this could imply for treatment of human hemostatic and immune disorders. 

 

L43: Suggest to use "attachment" rather than "fixation" which can be confusing.

 

L44: ... facilitate ectoparasitism ... (remove the)

 

L45: ... pathogenicity of arthorpod-borne (remove the)

 

L54: move "is notable" to the end of the sentence.

 

L101: I find the systematic review approach to be highly problematic since the choice of keywords actually present a very biased set of papers that is not representative of the field. For example, the study miss the following important proteins considered important for understanding tick-host interactions and that was at various times considered important for development of therapeutic agents:

Apyrase: This enzyme is secreted in the saliva of most tick species. In fact, it is one of the few conserved proteins found in tick saliva. It is also one of the first anti-hemostatics that was described. While this protein does not bind a target it does bind and hydrolyze ATP and ADP, effectively removing these immune and hemostatic agonists. This mechanism is considered similar to that of the histamine binding lipocalins since in both instances it scavenges agonists from the feeding sites. in fact, various studies have been published on tick apyrase (Ribeiro et al., 1985; Ribeiro et al., 1991; Mans et al., 1998; Mans et al., 2008; Stuzer et al. 2009).

Tick anticoagulant peptide (TAP): This protein  was one of the first anti-hemostatics isolated from ticks (Waxman et al. 1990). It was also one of the first that was extensively characterized as potential therapeutic agent. While it was isolated from whole ticks, its ortholog fXa inhibitor was isolated from salivary gland extract (Gaspar et al., 1995). It therefore follow that it would also be a salivary protein.

Variabilin: This was the first GPIIbIIIa inhibitor isolated from hard tick salivary glands (Wang et al. 1996).

OMCI: While OMCI is cited the original paper that described OMCI is not (Nunn et al., 2005). It is also not indicated that OMCI can bind leukotriene B4.

Leukotriene C4 binders: While the study cite leukotriene B4 scavengers, it fails to reference leukotriene C4 scavengers which is just as important in inflammatory responses (Mans and Ribeiro, 2008).

Cystatins: It may be noted that sialostatin L was described before sialostatin L2. Both target primarily cathepsins (Kotsyfakis et al. 2006, 2008). Indeed, after this a number of other cystatins was described from tick salivary glands. 

 

Figure 1: The relationsips depicted in the tree is incorrect. For example: Anomalohimalaya is a hard tick genus that is shown to group within the soft tick family. Similarly, Otobius group in the Ornithodorinae and basal to Ornithodoros, Carios and Argas. 

 

Table 1: It may be noted that Amblin was isolated from hemolymph and does not occur in the salivary glands or saliva.

 

Table 1: Monomine and Monotonin are not the only bioactive molecules described from Argas monolakensis. A fibrinogen receptor antagonist (monogrin), thrombin inhibitor (monobin) and leukotriene C4 scavenger (AM-33) was also described.

 

Table 1: Votucalis is the same protein as the Ra-HBPs. It was just renamed.

 

L219-221: The contention that soft ticks only target blood coagulation and vasoconstriction is not true. Soft ticks also secrete histamine and leukotriene binding proteins, complement inhibitors and cystatins.

 

L228, L254: Italicize species names.

 

L240: It is not clear why hard ticks show a predominance. Perhaps because more of them has been studied? Soft ticks also produce many proteins that target various proteins and ligands.

 

General: The study promised to highlight mechanism of action and how this could impact development of immunobiologics. However, listing targets is not the same as discussing mechanism of action. On this, the authors refer a lot to evasins and how little work has been done on these. However, several excellent studies on the mechanisms of evasins exist and I would argue that significant work has been done to date on evasin targets and mechanism of action. I would suggest that the authors define what they mean with mechanism of action since it generally refer to the molecular mechanism of action, ie. structure-function relationships. What they currently describe the target and the host defense pathways that are affected. The study is somewhat of a let down given that other extensive reviews on tick salivary gland biomolecules exist. In current form it repeats what other studies have said before. I would have liked to have seen how the mechanism of action was linked to immunobiologics. In this regard, it is strange that the authors do not discuss in more depth molecules that has been intensively investigated in the last 30 odd years with the explicit aim of developing them as clinical agents. A number of these exist for ticks.

 

L266: It is not clear why cytokine modulators are highlighted as having knowledge gaps. There are many protein family members for which no functions has been elucidated. The same statement can be made for all of the extensive tick family members found in salivary glands.

 

The supplementary material cite references not included in the material which does not correlate with references in the paper.

Examples:

Iwanaga 1926 [10] correlate with reference [41] in the paper. The date for this citation cannot be 1926, possibly 2003. All of the citations follow this same pattern. It is suggested that the supplementary material include its own set of references since the numbers do not correspond with what is in the paper.

 

Author Response

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Reviewer 2 Report

Comments and Suggestions for Authors In light of today's knowledge, it is a fact that tick saliva is a pharmacopoeia of biologically active products that perform different functions that allow these ectoparasites to successfully feed on the blood of their hosts and that facilitate the infection of the parasites they transmit. For this reason, this review could be very interesting to the scientific community working not only on ticks but also in medicine due to the potential use of these active molecules for therapeutic purposes of many diseases. However, the manuscript deserves improvements before publication.   In my opinion the aim should be reformulated. The authors did not identify the molecules present in tick saliva neither determine their ligands. This work was performed by other authors. The authors of this review have pretended putting together all these works in order to have a list of molecule/ligand previously publish which could be very useful and interesting. On the other hand, it is not clear for me what is the meaning of this statement " .... analyze the spatial and temporal distribution of studies related to these molecules" (Line 33 and line 79) as an aim of this review when they only have mentioned an increase in publications about this topic in 2008 in the discussion section without additional considerations. On the other hand, I also do not agree that the manuscript examines the possible uses of this molecules for treatment of a broad spectrum of hemostatic and immune-mediated disorders because in the discussion section the authors limit themselves to talking only a little about the functions of the described active molecules and do not go into depth about disorders that could be treated with these molecules. A title for Table 1 should be defined. In summary, I consider that the authors could take more advantages of this review to discuss more deeply implications of our knowledge of these molecules and their functions and their applications in order to control tick infestations and pathogen trasmissions.

 

   

 

Author Response

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Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

Review of Biomolecules-3270693, “Binding Molecules in Ticks for Targeting Host Cytokines, Chemokines and Beyond: A Scoping Review.”

The manuscript, “Binding Molecules in Ticks for Targeting Host Cytokines, Chemokines and Beyond: A Scoping Review,” provides a limited narrative review of published literature reporting identification and roles of immunomodulatory ligands present in tick saliva. As such, the manuscript provides a useful compilation of previous literature relating to specific immunomodulatory tick salivary ligands, however there are a number of significant deficiencies in the present form of the manuscript.

Key terms utilized in the database searches included Argasidae and Ixodida, but NOT Ixodidae, Immunoactive, or Immunomodulatory – Why?

Conference proceedings were excluded without apparent regard for lack of overlap in the remaining literature.

Title: “Binding Molecules in Ticks….” should include “…in Tick Saliva…”

The Introduction would benefit from a more detailed explanation of why the review study was undertaken, and an introduction for differences between hard ticks and soft ticks with respect to differences in their hosts and duration of feeding and how these factors might relate to different needs for anticoagulation, inhibition of vasoconstriction and complement fixation, and suppression of other host innate and acquired immune responses to tissue damage and tick feeding, as well as development of resistance to future tick feeding.

Figure 1. Remove “Disclaimer/Publisher’s Note” from Figure legend & move to Endnotes.

Table 1. Need Title for Table 1. Remove publisher note relating to Table placement.

Table 1: Inconsistent use of nomenclature (e.g., Interleukin-8/IL-8). Abbreviations not defined at first use (STRONGLY SUGGEST ADDITION OF TABLE LISTING ALL ABBREVIATIONS, INCLUDING PROTEIN/GENE IDENTIFICATION. Many terms are unnecessarily hyphenated (e.g.,chem-okines, pa-pain, Ex-hibits, comple-ment, serro-tonin,an-tagonist, plate-lets, in-duced, prolif-eration, path-way, keukotri-ene, de-lays, kal-likrein, coag-ulation, al-pha, Man-nose, etc.).

Discussion. Needs substantial expansion with more detailed explanation of tick salivary ligand roles and mechanisms of immunomodulation. Suggest reorganization according to soft tick/hard tick & why.

Author Response

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Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

The authors have addressed all issues in a satisfactory manner.

Author Response

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Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

The manuscript is much improved from the previous version, however, I do wish to point out two suggestions that would improve the readability and appropriate interpretation of the summarized studies:

1. Table 1 is currently presented in portrait orientation, leading to excessive hyphenation of terms in the columns due to space limitations. This could easily be greatly improved by changing the orientation of Table 1 to landscape, rather than portrait, thereby allowing more space in columns with greater text.

2. The authors indicate that tick salivary molecules may allow tick presence to remain undetected by the host (line 37, "evade detection"; line 158-159, "...allowing them to feed undetected by the host immune system..."). In my view, this is a misrepresentation in that tick presence may be detected, e.g. tissue damage plus presence of foreign molecules, but the appropriate action in response to molecular and cellular messages indicating the need to respond to tissue damage and presence of foreign molecules are thwarted, in a similar way to lack of appropriate monitoring of the alarm messages.

 

Author Response

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