Skin, Liver, and Kidney Interactions Contribute to Skin Dryness in Aging KK-Ay/Tajcl Mice

Round 1

Reviewer 1 Report

 In my opinion, this is an interesting, well designed and practical manuscript that deserves publication. Further comments about the manuscript are reported below.

1. Please disclose the detailed contribution of co-author Tsuneki Horikawa to this manuscript.

2. In the References section, the list was not prepared in accordance with the requirements of the journal

3. The section on survey methodology is not described in sufficient detail.

4. How many animals were used in the experiment? What was the number of animals in the control group versus the study group?

5. What equipment was used for image capture to assess histopathological changes in dorsal skin, kidney and liver samples?

6. What was the scale and what measurement lenses were used?

7. How many measurements were made for each sample taken from a particular animal?

8. Incorrect value of scale bars in the description of Figure 2

Author Response

To Reviewer 1

We would like to thank the reviewer for appreciation of our work.

 

1. Thank you for your comment. We added the contribution of Mr. Tsuneki Horikawa to this paper.

Author Contributions

K.H., S.T. wrote the article and designed the research. K.G., T.H. analyzed and interpreted the data, and K.O. contributed the essential regents and tools.

 

2. Thank you for your comment. Corrected the references section to the format of this journal.

References

 

3. Thank you for your comment. We have added a little more detail to the methods.

Materials and Methods

 

4. Thank you for your comment. We added the number of animals used per group.

   Materials and Methods

　 2.1. Animal experiments   n=5

    2.6. Statistical analysis    ・・・derived from five animals. 

 

5. Thank you for your comment. Added names of instruments used to assess

histopathologyical changes.

Materials and Methods, 2.3. Preparation and staining of dorsal skin, kidney, and liver samples p.2 lines 10-11

    BX51 Olympus microscope with UPlanSApo (Olympus, Tokyo, Japan) was used

    to these histological analyses.

 

6. Thank you for your comment. We added the meaning of the scale and the

information of the measurement lens.

Figure 2

Scale bar (Length unit display)

Materials and Methods, 2.3. Preparation and staining of dorsal skin, kidney, and liver samples p.2 lines 10-11

    BX51 Olympus microscope with UPlanSApo (Olympus, Tokyo, Japan) was used

 to these histological analyses.

 

7. Thank you for your comment. Samples were measured in duplicate.

   Materials and Methods, 2.6. Statistical analysis p.3 line 2

   Shown is a representative of 2 independent experiments.

 

8. Thank you for your comment. It’s our mistake. We rewrote it.

Figure 2

Scale bars = 100 mm. → Scale bars = 100 μm.

Author Response File: Author Response.pdf

Reviewer 2 Report

This paper entitled “Skin, Liver, and Kidney Interactions Contribute to Skin Dryness in Aging KK-Ay/Tajcl Mice” is informative, however, there are several concerns that need to be addressed as follows.

 

Major Concerns

Besides inflammation, several possibilities regarding dry skin linked to type 2 diabetes need to be considered.

When blood sugar levels are too high, many changes take place such as alteration of collagen networks causing stiff skin due to blood vessel damage or dehydration due to frequent urination etc.

Given that all the data from Figure 1 to 7 based on circumstantial evidence, the authors should present concrete evidence to what extent do liver and kidney interactions surely contribute to dry skin in aged diabetes mice?

Author Response

Response to the Reviewers’ comments

 

To Reviewer 2

We would like to thank the reviewer for appreciation of our work.

 

As the reviewer say, there are other possible causes of dry skin in type 2 diabetes.

 

(Discussion: p.11, line 44 - p.12, line 7):

As diabetes progresses, dehydrations occurs due to frequent urination, and excessively high blood glucose levels change the collagen network, causing damage to blood vessel and stiffening the skin, which also causes dryness [29]. In this study, we measured the amount of urination and water intake (data not shown), both of which increase with age. The difference in urine output and water intake was the same as in young diabetic nice, suggesting that the possibility of dryness due to dehydration is low. On the other hand, skin stiffness due to vascular injury is well considered, and markers of vascular injury should be invested. Furthermore, In this study concluded that kidney and liver are important for skin dryness because damage to kidney and liver increases with progression of diabetes and correlates with increased skin dryness with aging. However, there is no direct evidence that the kidney and liver are interrelated and exacerbate dry skin due to diabetes, and further investing is required.

 

(References 29):

29. Hofmann B, Adam AC, Jacobs K, Riemer M, Erbs C, Bushnaq H, Simm A, Silber RE, Santos AN. Advanced glycation end product associated skin autofluorescence: a mirror of vascular function? Exp Gerontol 2013; 48(1):38-44.

Author Response File: Author Response.pdf

Reviewer 3 Report

This is a well-designed study exploring skin dryness and ageing through the interaction of skin, kidneys and liver.

I have minor comments/suggestions:

1. In the title you use the word 'skin ageing' but do not include a clear definition of skin ageing and if measures that you explore are a definite marker of skin ageing.

2. You introduce your study by describing type 2 diabetes in people, and the study is performed on mice, but don't mention how the results can be generalized and if they can be extrapolated to also apply to humans. In the conclusion it may be necessary to point out that the results apply to mice.

The first sentence of Discussion you write: 'In this study, the effects of the liver and kidney on skin dryness were investing using and aging type 2 diabetes mouse model' Please correct this sentence, the grammar is wrong.

Author Response

Response to the Reviewers’ comments

 

To Reviewer 3

We would like to thank the reviewer for appreciation of our work.

 

1. Thank you for your comment. I’m sorry, but we don’t use the word “skin aging” in the title. Also, this paper does not mention skin aging. However, dry skin is one of the important indicators of skin aging*. In this study, diabetic model mice showed a marked increase in dry skin. Therefore, it is though that skin aging is also affected, and this is a subject for further investigation.

*White-Chu, F.E.; Reddy, M. Dry skin in the eldely: complexityes of a common problem. Clin. Dermatol. 2011, 29,37-42.

 

2. Thank you for your comment. We added the conclusion about how to apply this  research to humans.

(Conclusions: p.12, lines 7-11):

Based on these findings, it may be possible to create new drugs that target each organ in type 2 diabetes by further advancing this research. Furthermore, it may be possible to estimate the degree of kidney or liver damage by observing the skin condition. However, this study used mice, and it is necessary to confirm consistency with mice by conducting clinical trials on humans.

 

3. Thank you for your comment. We rewrote the first line “In this study, the effects of

the liver and kidney on skin dryness were investing using and aging type 2 diabetes mouse model (KK-Ay/Tajcl).”

   (Discussion: p.11, lines 1-2):

   In this study, the effects of the liver and kidney on skin dryness were investigated using aging type 2 diabetes mouse model (KK-Ay/Tajcl).

Author Response File: Author Response.pdf