Round 1

Reviewer 1 Report

Comments: Revisiting the role of local cryotherapy for acne treatment: a review and update

Manuscript is well-versed with the title and interesting to reader.

However, the manuscript is limited to the experts or scholars in terms of literature. 

1. The whole manuscript lacks clinical evidence in any tabular form or separate sections in data.

2. Side effects are minimized to section 6 in a very brief note, please rewrite it.

3. The manuscript need revisions and add the cellular and molecular insights about acne.

4. Author can refer this article in acne -https://doi.org/10.1016/j.hsr.2022.100042

5. Authors must specify that permission and consent have been taken for the figures where it is required.

These are the above suggestions for the manuscript. It requires revision before acceptance.  

Comments for author File: Comments.docx

Author Response

A point-by-point response to the reviewer’s comments (reviewer 1, round 1)

We would like to thank the reviewers for their thoughtful comments and efforts towards improving our manuscript. In the following, we present our response specific to each reviewer comments.

[Reviewer’s comment] 1) The whole manuscript lacks clinical evidence in any tabular form or separate sections in data.

[Authors’ response] Thank you very much for your valuable comment. As the reviewer kindly suggested, we added Table 1 to the revised manuscript. The table summarizes key findings from selected clinical studies regarding cryotherapy for acne treatment.

[Reviewer’s comment] 2) Side effects are minimized to section 6 in a very brief note, please rewrite it.

[Authors’ response] We appreciate the reviewer’s suggestion. We rewrote the section with subsections and included more information on various side effects of cryotherapy, and some rare side effects are also mentioned in the revised manuscript.

[Reviewer’s comment] 3) The manuscript need revisions and add the cellular and molecular insights about acne.

[Authors’ response] Thank you very much for the recommendation. According to the reviewer’s suggestion, we revised the section 4-2. Possible mechanisms of action, with new sentences focusing on the general and cellular/molecular aspects of acne pathogenesis.

The new sentences in the revised manuscript are as follows:

Important factors that play a role in the genesis of acne formation include hormones, inflammatory mediators, Cutibacterium acnes, and genetics. Testosterone and andro-gens cause activation and proliferation of keratinocytes, sebaceous cells, and ductal lining cells of the hair follicle, which accumulate in the pilosebaceous unit and result in the formation of pore obstruction and more sebum production. Oxygen availability within the cells can be compromised by the pressure exerted inside the pilosebaceous unit, providing ideal environmental conditions for the growth of C. acnes which further promotes acne formation (49). /…/ It has been noted that cold exposure induces the release of fewer pro-inflammatory cytokines (IL-2, IL-6, IL-8, IL-9, and TNF-α, among many others) and more anti-inflammatory cytokines (mainly IL-10), in addition, improve humoral and cellular immunity, stimulating B lymphocytes and natural killer lymphocytes (NK cells) (42). /…/ Cellular mechanisms governing acne pathogenesis include insulin-stimulated activation of the PI3K-Akt signaling pathways along with mTOR in sebocytes, resulting in increased synthesis of proteins and lipids, cell proliferation, and inflammation (49). Insulin has been reported to decrease in cold conditions (56), which may imply the possible role of cryotherapy in inhibiting the activation of the signal pathways during acne development.

[Reviewer’s comment] 4) Author can refer this article in acne -https://doi.org/10.1016/j.hsr.2022.100042.

[Authors’ response] Thank you very much for your valuable recommendation. The recommended reference (Lalrengpuii J, Raza K, Mishra A, Shukla R. Retinoid nanoparticles: approachable gateway for acne treatment. Health Sci Rev. 2022;4:100042) was included in the bibliography and referred in the revised manuscript (section 4.2. Possible mechanisms of action) as reference 49.

[Reviewer’s comment] 5) Authors must specify that permission and consent have been taken for the figures where it is required..

[Authors’ response] We appreciate the reviewer’s comment. We specified in the figure legends (Figures 4 and 5) that clinical photos of patients are used with permission and consent.

Again, we would like to show our deepest appreciation regarding the reviewer’s valuable comments and suggestions.

On behalf of the authors,

Nark-Kyoung Rho (the corresponding author)

Author Response File: Author Response.pdf

Reviewer 2 Report

I read with great interest your manuscript entitled "Revisiting the role of local cryotherapy for acne treatment: a review and update". In this article, the Author narratively reviewes the literature to characterize the role that cryosurgery has historically played in acne vulgaris and the new perspectives made possible by the latest available studies on the subject. In fact, the Author analyzes the results of the first studies available in relation to cryosurgery for acne (dating back to more than a century ago) up to the studies carried out in recent years with the use of modern devices capable of modulating the skin temperature. 

Physical treatments are somewhat regarded as obsolete therapies for acne vulgaris and of pure historical interest. The Author collects sufficient evidence to state that there are some instances in which cryosurgery can be useful for acne therapy, even if not as a first-line. Finally, the author describes the histological and molecular mechanisms underlying the efficacy of cryosurgery in acne treatment.

Nonetheless, I suggest some minor revisions:

- Risk of atrophic scars: although the author adequately addresses the risk of post-procedural hypo- and hyperpigmentation, the risk of cryosurgery-induced skin atrophy is not mentioned. In fact, atrophic scars are a long-term consequence of acne vulgaris that can impact the quality of life. If there is some evidence in relation to the risk of post-cryosurgery atrophy, the Author should mention it; if no data in this regard is available, this fact should be clearly stated.

- The role of cryosurgery in other inflammatory conditions: acne vulgaris is regarded as a primary inflammatory disease rather than an infectious condition. On the other hand, other inflammatory or immune-mediated cutaneous diseases are worsened by cryosurgery: for example, in psoriasis cryosurgery may induce an isomorphic response (koebner phenomenon). In addition to hidradenitis suppurativa, the Author should mention the possible role of cryosurgery in other inflammatory diseases

- Line 353-354: “and the difference was statistically significant (92). In addition, cryotherapy has a role in treating needle-phobic”: the Author states that there is a difference between the analgesia obtained with nitrogen spray and another measure. The author should specify what is the other measure referred to (ice-cold packs? No treatment?). Finally, the sentence “In addition, cryotherapy has a role in treating needle-phobic” is redundant and should be omitted.

- Line 366-388: “The author’s experience shows a significant difference in clinically relevant pain during intralesional triamcinolone injections with and without lesional cooling when treating acne. Upon retrospective analysis of 65 adolescent acne patients of the first author (unpublished data), the median pain score was significantly lower for those that received a combination treatment (cryotherapy and intralesional injection) than those that received intralesional injection monotherapy (3.0 vs. 5.0, p<0.00001) […]” the author should not include previously unpublished and/or not peer-reviewed data in this manuscript, since it is a narrative review of the Literature. Anything that refers to the personal experience of the Author or to non-peer-reviewed data (including fig. 6) should be omitted from this manuscript

- Line 428-429: “According to the authors’ experience, a very weak cooling of around –3°C is sufficient in reducing injection pain, as in our clinical data”: as previously stated, any references to unpublished data or personal opinions should not be included in the manuscript

- Line 434 “The “counterirritant” effect, which occurs when a temperature stimulus overrides a painful stimulus”: the Author defines “counterirritant effect” the overriding of a painful stimulus by a temperature stimulus; on the other hand, in line 198 the Author defines “counterirritant” effect the one causing inflammatory lesions to disappear faster than without treatment. Using the same term to define two distinct biological effects is a potential source of confusion. 

- Line 456-457: “With a temperature of around –10°C, cooling damages sebaceous glands, increases enzymatic activities”: it is known that enzymatic activity tends to decrease at low temperatures. The author should mention which enzymes of the sebaceous unit increase their activity at low temperatures.

Author Response

A point-by-point response to the reviewer’s comments (reviewer 2, round 1)

We would like to thank the reviewers for their thoughtful comments and efforts toward improving our manuscript. We present our response specific to each reviewer's comments in the following.

[Reviewer’s comment] 1) Risk of atrophic scars: although the author adequately addresses the risk of post-procedural hypo- and hyperpigmentation, the risk of cryosurgery-induced skin atrophy is not mentioned. In fact, atrophic scars are a long-term consequence of acne vulgaris that can impact the quality of life. If there is some evidence in relation to the risk of post-cryosurgery atrophy, the Author should mention it; if no data in this regard is available, this fact should be clearly stated.

[Authors’ response] Thank you very much for your valuable comment. As the reviewer pointed out, we added a new subsection (6.3. Scarring) which describes the possible scarring (both hypertrophic and atrophic) after cryotherapy.

The new sentences in the revised manuscript are as follows:

Scarring is rare after cryotherapy at temperatures of −7.5°C or warmer (98). However, aggressive cryotherapy can cause hypertrophic or even atrophic scarring (22,43). Since atrophic scarring is a long-term consequence of acne vulgaris that can heavily impact the patient’s quality of life, aggressive freezing may not be adequate for treating acne.

[Reviewer’s comment] 2) The role of cryosurgery in other inflammatory conditions: acne vulgaris is regarded as a primary inflammatory disease rather than an infectious condition. On the other hand, other inflammatory or immune-mediated cutaneous diseases are worsened by cryosurgery: for example, in psoriasis cryosurgery may induce an isomorphic response (koebner phenomenon). In addition to hidradenitis suppurativa, the Author should mention the possible role of cryosurgery in other inflammatory diseases

[Authors’ response] We appreciate the reviewer’s suggestion. Indeed, the role of cryotherapy in treating inflammatory skin disorders other than acne is worth mentioning, as the reviewer pointed out. In the revised manuscript, we added a new section (3.6. Other inflammatory dermatoses) and included more information on the use of cryotherapy for other inflammatory dermatoses.

The new sentences in the revised manuscript are as follows:

The role of cryotherapy in treating other inflammatory skin conditions is worth mentioning since acne vulgaris is regarded as a primary inflammatory disease rather than an infectious condition. Although research on the impact of individual skin characteristics is inconsistent, positive effects on reducing inflammation and oxidative stress have been noted, supported by clinical reports of cryotherapy successfully used in several inflammatory skin conditions (9,37), including atopic dermatitis (42). Cryotherapy was also reported to be effective in treating psoriasis (43), although many clinicians have hesitated to use cryosurgery in psoriasis since cold injury may induce an isomorphic response (the Koebner phenomenon).

[Reviewer’s comment] 3)Line 353-354: “and the difference was statistically significant (92). In addition, cryotherapy has a role in treating needle-phobic”: the Author states that there is a difference between the analgesia obtained with nitrogen spray and another measure. The author should specify what is the other measure referred to (ice-cold packs? No treatment?). Finally, the sentence “In addition, cryotherapy has a role in treating needle-phobic” is redundant and should be omitted.

[Authors’ response] We sincerely appreciate the reviewer’s valuable comment. We rewrote the sentence for clarity.

The new sentence in the revised manuscript is as follows:

A recent prospective, open trial involving 21 dermatologic patients who received intralesional triamcinolone injections revealed that the mean pain reduction was 3.4 (a numeric rating scale, 0 to 10) in the liquid nitrogen spray cooling group and 6.9 in no cooling control group (p<0.001) (92).

The last sentence (“In addition, cryotherapy has a role in treating needle-phobic (16).”) has been deleted as the reviewer suggested.

[Reviewer’s comment] 4) Line 366-388: “The author’s experience shows a significant difference in clinically relevant pain during intralesional triamcinolone injections with and without lesional cooling when treating acne. Upon retrospective analysis of 65 adolescent acne patients of the first author (unpublished data), the median pain score was significantly lower for those that received a combination treatment (cryotherapy and intralesional injection) than those that received intralesional injection monotherapy (3.0 vs. 5.0, p<0.00001) […]” the author should not include previously unpublished and/or not peer-reviewed data in this manuscript, since it is a narrative review of the Literature. Anything that refers to the personal experience of the Author or to non-peer-reviewed data (including fig. 6) should be omitted from this manuscript.

[Authors’ response] First, the authors would like to apologize for the inappropriate writing of a narrative literature review in the first manuscript. As the reviewer strongly suggested, we decided to delete all the sentences and figure 6, describing the personal data which has not been published nor peer-reviewed.

The deleted sentences in the revised manuscript are as follows:

The author’s experience shows a significant difference in clinically relevant pain during intralesional triamcinolone injections with and without lesional cooling when treating acne. Upon retrospective analysis of 65 adolescent acne patients of the first author (unpublished data), the median pain score was significantly lower for those that received a combination treatment (cryotherapy and intralesional injection) than those that received intralesional injection monotherapy (3.0 vs. 5.0, p<0.00001). Figure 6 shows a histogram comparing each cohort's pain rating scale scores. There were no serious adverse outcomes secondary to the procedures, except for one patient who developed a focal area of hyperpigmentation after cryotherapy, which was mild and resolved spontaneously in eight weeks.

[Reviewer’s comment] 5) Line 428-429: “According to the authors’ experience, a very weak cooling of around –3°C is sufficient in reducing injection pain, as in our clinical data”: as previously stated, any references to unpublished data or personal opinions should not be included in the manuscript.

[Authors’ response] We deleted the phrase describing an unpublished personal experience. We rewrote the sentence as follows: A weak cooling of around –3°C is sufficient in reducing injection pain, as shown in the study by Jung et al. (97).

[Reviewer’s comment] 6) Line 434 “The “counterirritant” effect, which occurs when a temperature stimulus overrides a painful stimulus”: the Author defines “counterirritant effect” the overriding of a painful stimulus by a temperature stimulus; on the other hand, in line 198 the Author defines “counterirritant” effect the one causing inflammatory lesions to disappear faster than without treatment. Using the same term to define two distinct biological effects is a potential source of confusion.

[Authors’ response] We admit that we used confusing definitions of “counterirritant,” as the reviewer pointed out. The first phrase describing the term “counterirritant” was deleted and rewrote as follows: Although not fully founded in evidence, it is generally regarded that freezing causes inflammatory lesions to disappear faster than without treatment (15).

[Reviewer’s comment] 7) Line 456-457: “With a temperature of around –10°C, cooling damages sebaceous glands, increases enzymatic activities”: it is known that enzymatic activity tends to decrease at low temperatures. The author should mention which enzymes of the sebaceous unit increase their activity at low temperatures.

[Authors’ response] We would like to deeply apologize for our mistake in writing the sentence. As the reviewer pointed out, enzymatic activities tend to DECREASE rather than INCREASE at lower temperatures. It was our mistake to erroneously use a verve “increase” in the original submission. We changed the word “increases” to “disrupts.” We rewrote the sentence: With a temperature of around –10°C, cooling damages sebaceous glands, disrupts some enzymatic activities, and reduces sebum output for two weeks, with minimal injury to surrounding tissues (60).

Again, we would like to show our deepest appreciation for the reviewer’s valuable comments and suggestions.

On behalf of the authors,

Nark-Kyoung Rho (the corresponding author)

Author Response File: Author Response.pdf

Reviewer 3 Report

Abstract

The abstract is well structured and it highlights the main ideas of the study, while also engaging the interest of its target reading audience. Furthermore, there is a decidely academic use of english language.

The manuscript is structured in eight parts:

1.      Introduction

2.      Brief History and Early Reports of Acne Cryotherapy

3.      Cryotherapy for Acne

4.      Mechanism of action

5.      Adjunctive Uses of Cryotherapy in Acne Treatment

6.      Side Effects

7.      Acne Cryotherapy: What is the Optimal Temperature?

8.      Conclusion

1.      Introduction

The introduction is coherent, throughtly documented, it summarizes the manuscript and explains the utility of the study in future medical practice, in an adequate and fluent language.

2.      Brief History and Early Reports of Acne Cryotherapy

This chapter consists of three different subchapters, presenting a brief history and early reports of acne cryotherapy. The reader is provided with an insight regarding the evolution of cryotherapy, but although it is very interestingly presented, the information might not very much appealing to nowadays practice, as the storyline could be a little over-detailed, thus I suggest summarizing it.

3.      Cryotherapy for Acne

The author explains the subtypes of acne that can be treated using cryotherapy, based on several studies, but also the selection of patients that can benefit from this treatment and the drawbacks of this therapy. 

4.      Mechanism of action

The reader is being explained the mechanism of action in a very detailed manner, taking into account histologic studies, effects on the sebaceous gland but also many other possible mechanisms. The language is used in an appropriate and explicit manner.

5.      Adjunctive Uses of Cryotherapy in Acne Treatment

This part consists of valuable data about the combination therapy, based on evidence from recent studies, much useful for today’s practice.

6.      Side Effects

The side effects are presented in a very correct manner, from the most frequent to the infrequent ones, based on the evidence from many different studies.

7.      Acne Cryotherapy: What is the Optimal Temperature?

This topic is very useful and of major interest for the specialists who would use this therapy for their selected patients, as many different devices and their technology is presented. The quality of the data presented is good and the facts are evidence-based.

8.      Conclusion

The conclusion is supported by the data presented and it shows the importance of such a study in providing this treatment option for a selected group of patients. The key papers discused are appropriately cited. However, many of the papers were not very recently published, so there is a need of more modern studies and controlled trials with larger sample sizes to confirm the efficacy of this treatment, as the author himself suggests. For the study to get more appealing to nowadays practice, I suggest implementing more papers that are published in the recent years.

Quality of English language

In my opinion, the manuscript should not be language edited prior to acceptance, as the language is appropriate and fluent.

Overview

In conclusion, this article consists of valuable research which might prove to make a difference in the treatment options of various types of acne, in selected patients.

Overall, the manuscript should be accepted with minor editing.

Author Response

A point-by-point response to the reviewer’s comments (reviewer 3, round 1)

The authors would like to thank all the reviewers for their thoughtful comments and efforts toward improving our manuscript. We would like to appreciate the cheering comments from this reviewer 3 especially. We present our response specific to a suggestion by the reviewer (reviewer 3) in the following.

[Reviewer’s comment] 1) Brief History and Early Reports of Acne Cryotherapy: This chapter consists of three different subchapters, presenting a brief history and early reports of acne cryotherapy. The reader is provided with an insight regarding the evolution of cryotherapy, but although it is very interestingly presented, the information might not very much appealing to nowadays practice, as the storyline could be a little over-detailed, thus I suggest summarizing it.

[Authors’ response] Thank you very much for your valuable recommendation. As the reviewer suggested, we deleted subsection headings and merged the separate subsections into a single section (2. Brief History and Early Reports of Acne Cryotherapy). Several detailed historical aspects have been deleted to make the section more concise.

The new section in the revised manuscript is as follows:

Dermatologic cryosurgery textbooks and scholarly reviews credit James Arnott, who is widely regarded as the “father of modern cryosurgery” (2,3). In his own words, Arnott described his cryotherapy technique as “congelation arresting the accompanying inflammation and destroying the vitality of the cancer cell (2)”. In addition to treating tumors, Arnott also proposed that cryotherapy could be utilized to treat other dermatologic conditions, including acne vulgaris. Arnott won the prize medal at the Great Exhibition of London of 1851 for his cold equipment that allowed reducing tissue temperature to ₋20 °C (4) (Figure. 1).

From Arnott’s early work, the practice of cryotherapy has blossomed into a staple in the practice of modern dermatology (5). Arnott's idea led to the development of a more practical cryotherapy device consisting of carbon dioxide collector and com-pressor units, which John Hall-Edwards described in 1911 (6) (Figure 2). In 1925 Giraudeau (cited by (7)) commenced using cryotherapy for acne, with a mixture of solid carbon dioxide (₋78.5 °C), acetone, and precipitated sulfur, which was later found out by Dobes et al. (8) to produce better results in papulopustular acne than in nodular lesions. It produces erythema and desquamation, of which the degree is determined by the time the slush is in contact with the skin (9).

At the end of the 19th century, all the so-called “permanent gases” (oxygen, nitrogen, and hydrogen) were liquefied, and commercial liquefaction of air was established by Carl Von Linde (4,6). Campbell White used a glass flask that acted as a liquid air sprayer, which became the first portable cryosurgery device (Figure 3) (4). During the 1920s and 1930s, liquified oxygen (₋182.9 °C) was used as a cryogenic agent to treat various skin conditions, including acne (3). However, liquid oxygen soon became obsolete as a cryogenic agent because of its high combustibility (10).

Liquid nitrogen (₋196 °C) became commercially available and was introduced into clinical practice in 1950 by Herman V. Allington (11), who was the first to publish on the successful use of liquid nitrogen to treat acne. Allington used a cotton swab dipped in liquid nitrogen (4,11). Later reports in the 1970s mainly used liquid nitrogen as a cryogen source to treat acne. A study of 150 acne patients treated with liquid nitrogen cryotherapy reported excellent results in 95 % of cases (12). In 1973, Goette (13) also reported that liquid nitrogen cryotherapy is effective in treating acne. In 1967, Setrag Zacarian, who brought the term “cryosurgery” into use for the first time, designed a handheld cryosurgical device using liquid nitrogen which gave rise to several models of handheld cryosurgical units (14).

Again, we would like to show our deepest appreciation for the reviewer’s valuable comments and suggestions.

On behalf of the authors,

Nark-Kyoung Rho (the corresponding author)

Author Response File: Author Response.pdf