Physiological effects of appropriate washing on xerotic skin

Daily skin care is important for treatment of skin diseases, but few studies have reported on appropriate washing methods.

other natural moisturizing factors in the stratum corneum, as well as lead to accretions, and can encourage xerotic skin symptoms. 1,24][5] Washing when bathing is less likely to be scrutinized by others and, above a certain age, by one's family, and one may unintentionally cultivate and sustain inappropriate skin care practices.
The aim of this study was to find an appropriate skin care method for washing.Therefore, we conducted an internet survey on skin conditions and skin care methods among 668 general subjects without serious underlying diseases.These results were used to develop the washing guidance method; patients with atopic or asteatotic dermatitis, or other conditions that tend to impair the skin barrier function, were instructed on how to wash dry skin.The changes resulting from the use of appropriate cleansers were examined from a physiological and functional perspective.

| Internet survey of skin condition and skin care methods
An internet survey on skin conditions and daily washing methods was conducted, with 668 males and females registered with the Fastask® online survey.The participants were aged 20-69 years and had no serious underlying diseases.Each age group included a range of 66-69 participants of each sex.

| Duration and study site
The study was performed at the Department of Dermatology at our institution, with approval of our institution's Clinical Study Review Board and in conjunction with NOV Academic Research, TOKIWA Pharmaceutical Co., Ltd.

| Study participants
This was a left-right comparative nonrandomized study with no control group.Study participants were patients who were diagnosed with atopic or asteatotic dermatitis, showed stable symptoms regardless of whether or not they used topical or oral treatments, and were capable of deciding whether to agree to ongoing participation in this study.Patients who met the following criteria were excluded: • Those with a rash, injury, or bleeding not relevant for evaluation in this study.
• Patients with complications or those using other therapeutic topical agents that may affect study evaluation.
• Patients unable to attend medical examinations at 4 and 8 weeks after the start of the study.
• Those otherwise judged unsuitable for participation in this study by the attending physician.

| Study schedule and guidance on washing methods
At the start of the study, an attending physician provided the study participants with guidance on washing methods, which is detailed in Table 1.An attending physician also provided the study participants with a fact sheet describing the guidance in detail and instructed them to practice the washing method at home.

| Guidance on washing methods (from the start of study to Week 4)
At the start of the study, an attending physician asked the study participants about their daily washing methods.Based on the responses received, the study participants were provided with guidance on appropriate washing methods (Table 1).All study participants were supplied with the same cotton towel (TK cotton towel; Towa Industry Co., Ltd.) for use when washing the body.Patients continued to use their own skin cleanser.

| Treatments and medications during the study
The study participants continued treatments for underlying diseases or complications that were used before the start of the study and, as a general rule, did not change the type, administration method, or dosage of medications (topical and oral) during the study.However, such changes could be made if medically necessary, and an attending physician described the medication type, administration method, dosage, and expected effect on the study on a case card.

| Observation and evaluation methods
An attending physician entered the individual's anonymized study participant code (enables tracing; assigned at the start of the study), as well as the age, sex, complications, and concomitant drugs used during the study (drug name, administration method, dosage) onto a case card.An attending physician also took skin measurements with equipment and collected stratum corneum cells by tape stripping to determine the ceramide content and measure the thymus and activation-regulated chemokine (TARC) stain intensity.These observations were performed on the inner forearms and lower legs.

| Skin findings
The severity of atopic dermatitis and asteatotic dermatitis over the whole body was graded on four levels (slight, mild, moderate, and severe) at the start of the study, Weeks 4, and 8.The severity of erythema, desquamation, xerosis, pruritus, and excoriation on the inner forearms and lower legs was graded on five levels (none: 0, slight: 1, mild: 2, moderate: 3, severe: 4), and the sum of the scores was used as the total skin score.

| Skin measurements
The items mentioned below were measured at the start of the study, Weeks 4, and 8. Before measurement, the measurement sites were washed with a skin cleanser or wiped with purified water.The study participants then waited at rest for approximately 20 min with the measurement site exposed in a room held at constant climate conditions (temperature: 21 ± 2°C, relative humidity: 50% ± 5%).

Measurement of stratum corneum water content and transepidermal water loss.
The conductance of the inner forearms and lower legs was measured five times using a 3.5 MHz high-frequency conductance analyzer (SKICON®-200EX; Yayoi Co., Ltd.Tokyo, Japan); the mean value was used as the water content of the stratum corneum.A Tewameter® TM210 (Courage+Khazaka electronic GmbH) was used to measure transepidermal water loss at the test site twice, and the mean value was used.

Analysis of stratum corneum cells.
Stratum corneum cells were harvested by tape stripping with cellophane tape (CELLOTAPE™ CT-24, NICHIBAN Co., Ltd.), ceramide content was quantified on the inner forearm by the method described below, and TARC staining of the lower leg was performed.

| Ceramide content
Ceramides were quantified by thin-layer plate chromatography. 6ramide content per unit protein was also calculated using phosphate-buffered saline (PBS) buffer to elute soluble protein from the same length of tape from the same site used to measure ceramide content and measuring the amount of eluted soluble protein via the bicinchoninic acid method.2.6 | Survey assessing ease of adopting washing guidance After 8 weeks, the study participants were surveyed on the usability of the foaming skin cleanser and washing methods.

| S TATIS TIC AL ANALYS IS
In the usage study, data are expressed as mean ± standard devia-

| Internet survey on skin condition and skin care methods
When asked about general skin symptoms, the most common response was xerosis from 56.7% of respondents, followed by itchiness from 33.8%, scaling from 16.6%, redness from 10.3%, and pain from 4.0%.Almost skin symptoms tended to be more prevalent in females than in males (Figure 1A).When asked about the form of skin cleanser used, the most common response was liquid cleanser from 56.7% of respondents, followed by solid soap from 38.2%, and foaming cleanser from 3.6%, with no major difference between males and females (Figure 1B).When asked about washing methods, the most common accessory was a towel or sponge made of nylon or another synthetic material from 48.1% of respondents, followed by a towel or sponge made of natural material such as cotton or hemp from 23.4%, and bare hands from 19.0%.A towel or sponge made of nylon or another synthetic material was the most prevalent accessory among both men and women (Figure 1C).When asked about the degree of lathering, the highest proportion of respondents who answered "I create a good lather" was among people who use a towel or sponge made of a mix of natural and synthetic material (79.5%), followed by people who use a towel or sponge made of nylon or another synthetic material (76.9%), people who use a towel or sponge made of natural material such as cotton or hemp (66.0%), and then people who use bare hands (55.9%).A significant difference was noted between people who wash with bare hands and those who use a towel or sponge made of nylon or another synthetic material (Figure 1D).2).
One study participant with mild atopic dermatitis (29-year-old female, complications: cholinergic urticaria) noticed red papules with itching on all four extremities, including the study evaluation sites, 1 day after starting the study; at her own discretion, she stopped using the cotton towel provided during instruction.
The causal relationship between this event and cotton towel use is unknown; however, based on the symptoms and timing of onset, cholinergic urticaria induced by bathing appears likely.This study participant was excluded, and evaluation was performed on 18 study participants.

| Skin findings
The five-level scoring of skin symptoms on the inner forearms and lower legs revealed a significant reduction in the scores for erythema, desquamation, and xerosis and in the total skin score of the lower legs (Table 3).

| Skin measurements and analysis of stratum corneum cells
After 4 weeks, the water content ratios of the inner forearms and lower legs were 1.14 ± 0.50 and 1.19 ± 0.59, respectively.Moreover, transepidermal water loss in the inner forearms and lower legs was

| Skin findings
A significant reduction was noted in scores for erythema, xerosis, and pruritus and in the total skin score on the inner forearm side washed with bare hands, and a significant reduction was noted in scores for xerosis, pruritus, and excoriation and in the total skin score on the inner forearm side washed with a cotton towel (Table 3).

F I G U R E 1
Internet survey of skin care methods.An internet survey was conducted among 668 males and females (66-69 males and females in each age group, aged 20-69 years, and without serious underlying diseases), regarding their skin conditions and daily washing methods.

| Skin measurements and analysis of stratum corneum cells
The stratum corneum water content ratios after 4 weeks were 1.00 ± 0.00.After 8 weeks, the water content ratio of the inner forearm was 1.22 ± 0.77 on the side washed with bare hands and 1.12 ± 0.40 on the side washed with a cotton towel.On the lower legs, the relative water content after 8 weeks was 1.02 ± 0.59 on the side washed with bare hands and 0.95 ± 0.49 on the side washed with a cotton towel.Moreover, a significant reduction was noted in transepidermal water loss of the inner forearm from with a cotton towel.
The stratum corneum ceramide content ratios of the inner forearm after 4 weeks were 1.00 ± 0.00, and the ratios were 1.62 ± 1.03 for the hand-washed side and 1.42 ± 0.55 for the side washed with a cotton towel, both increased significantly after 8 weeks (p = 0.017 and p = 0.009, respectively).The TARC levels of the lower leg after 4 weeks were 1.00 ± 0.00; after 8 weeks, these levels were 0.75 ± 0.21 for the side washed with bare hands and 0.83 ± 0.42 for the side washed with a towel, both decreased significantly (p = 0.001 and p = 0.008, respectively) (Table 4B).

| Survey assessing ease of adopting washing guidance
When asked about the ease of adopting washing guidance, 6 of 16 study participants responded that "Create a good lather" was difficult to adopt."Do not scrub," "Wash in sequence," and "Rinse with tepid water" were considered difficult to adopt by three, two, and two study participants, respectively (Table 5A).When asked about foaming skin cleansers, all 17 study participants who returned the survey responded that foaming skin cleanser was an advantage, and 15 study participants responded that saving time on creating a lather was an advantage (Table 5B).

| DISCUSS ION
Responses to the internet survey of washing methods and skin symptoms showed that liquid cleansers, followed by solid soap, were most commonly used to wash the body.The most common washing accessory was a towel or sponge made of nylon or another synthetic material.Moreover, a significant difference was noted in the degree of lathering between people who wash with bare hands and those who use a towel or sponge made of nylon or another synthetic material, and lathering was inadequate when washing with bare hands.
Responses also showed that many people develop skin symptoms   Nineteen patients with atopic or asteatotic dermatitis and xerotic symptoms were provided with guidance on creating a good lather with a cotton towel and their current skin cleanser.They were then asked to use a foaming skin cleanser that creates a lather even when washing with bare hands and to use bare hands and a cotton towel to wash separate sides of the body.These washing methods were then compared among the 19 patients.
The skin of patients with atopic dermatitis exhibits a reduced Responses to the survey demonstrated that all the study participants felt that the foaming skin cleanser was advantageous, revealing that they accepted the convenience of the foaming skin cleanser.
More study participants responded that the guideline "Create a good lather" was difficult to adopt when compared with other guidelines, such as "Rinse with tepid water."We thus assumed that many people might not create a good lather, even when they know it is of benefit.
When considering everyday washing of the body, this result indicates that easy-to-understand guidance that is easy to adopt will be effective, such as using foaming skin cleanser that produces an optimum lather without effort, washing with bare hands or a soft towel, not scrubbing, avoiding very hot water, and rinsing thoroughly.
This study has some limitations.Due to the limited number of participants, the study was conducted as a nonrandomized trial using a left-right comparison design.In the future, randomized trials with a large sample size should be conducted.Further, the generalizability of these findings is limited, as the study only included the Japanese  TA B L E 5 Survey assessing ease of adopting washing guidance.

2. 3 . 2 |
Guidance on washing methods and using a foaming skin cleanser (from Weeks 4 to 8) The study participants' skin cleanser was changed to a foamingtype skin cleanser (NOV® foaming soap D; NOEVIR Co., Ltd., and TOKIWA Pharmaceutical Co., Ltd.).Patients with an odd enrollment number washed the left side of the body with bare hands and the right side of the body with the cotton towel, and the study participants with an even enrollment number did the reverse.The foaming skin cleanser was a liquid-type fatty acid soap consisting of myristic acid and palmitic acid neutralized with potassium hydroxide.The cleanser was bottled within a container that discharged the skin cleanser components as a lather at an optimum concentration.The foaming skin cleanser reduces physical irritation arising from friction and reduces skin dryness after washing with sorbitol, glycerin, or other moisturizing components.According to the Pharmaceutical Affairs Act (Act on Securing Quality, Efficacy and Safety of Products Including Pharmaceuticals and Medical Devices), this foaming skin cleanser is classified as a cosmetic.

TA B L E 1
Guidance on washing and comparing left and right sides.

From start of the study to Week 4 From Weeks 4 to 8 ( 1 ) Washing guidance ( 2 ) 4 Rinsing
Washing guidance and use of a foaming skin cleanser Type of skin cleanser Use the same skin cleanser Switch to a foaming skin cleanser Degree of lathering Create a good lather with a cotton towel Use lather created with a foaming skin cleanser Washing accessory Use a cotton towel Wash left and right sides separately with a cotton towel or bare hands Odd numbers: left side -bare hand, right side -towel Even numbers: left side -towel, right side-bare hand Washing method Wash gently by stroking and not scrubbing Same as Weeks 1-4 Washing sequence Wash in sequence from the head and face downwards Same as Weeks 1-4 Rinse water temperature Rinse with tepid water (not too hot) Same as Weeks 1-Pour fresh water over self about 10 times, or if showering, rinse for about 1 min and do not miss anything Same as Weeks 1-4 2.5.4 | TARC level Immunohistological staining was performed with anti-TARC antibodies (mouse anti-human CCL17/TARC monoclonal antibody [MAB364; R&D Systems]).After staining, fluorescence images obtained with a fluorescence microscope (BZ-8100; Keyence) were analyzed in Adobe® Photoshop® CS (Adobe Inc.), and the mean luminous intensity (calculated from five visual fields) was used as the TARC stain intensity.7

4. 2 |
Usage study 4.2.1 | Study participants' characteristics This study included a total of 19 study participants with a mean age of 34 ± 11 (range: 19-58) years.The mean disease duration was 26 ± 10 years in patients with atopic dermatitis and 6 ± 5 years in patients with asteatotic dermatitis.Of the 15 study participants with atopic dermatitis, disease severity was slight in two study participants, mild in seven study participants, moderate in six study participants, and severe in zero study participants.Of the four study participants with asteatotic dermatitis, disease severity was slight in one study participant, mild in two study participants, moderate in zero study participants, and severe in one study participant.Concomitant medications were topical steroids in 16 study participants, tacrolimus ointment in 7 study participants, topical drugs used as moisturizing or protective agents in 11 study participants, and oral antiallergy drugs in 12 study participants.Complications included allergic rhinitis, hay fever, bronchial asthma, asthma, cholinergic urticaria, and food allergy.No study participant changed their topical or oral medication (neither type, administration method, nor dosage) during the study (Table

4. 4 |
Guidance on washing methods and using a foaming skin cleanser (from Weeks 4 to 8)

Washing guidance (from start of the study to Week 4 )
Washing guidance and use of a foaming skin cleanser (from Weeks 4Note: n = 18, mean ± S. D., Wilcoxon signed-rank test.*p< 0.05.**p < 0.01.
skin barrier function due to xerotic symptoms,6,8,9 requires a skin cleanser that maintains the skin barrier function and does not cause excessive loss of epidermal sebum or moisturizing factors from the stratum corneum.In this study, the study participants were given guidance on the correct method of lathering with a cotton towel, regardless of the skin cleanser, in addition to using a foaming skin cleanser that avoids the problem of inadequate lathering, even when washing with bare hands.Adopting these changes did not exacerbate the underlying disease severity or skin findings.Instead, xerotic symptoms were improved, and patients with atopic or asteatotic dermatitis and xerotic symptoms could use the cotton towel and adopt the guidance without concern.When the foaming skin cleanser was used from week 4 of the study, a comparison of washing with bare hands versus a cotton towel showed only slight difference between the methods; both methods improved transepidermal water loss, stratum corneum ceramide content, and TARC levels.Guidance on lathering and washing methods in the first half of the study resulted in an immediate improvement in xerosis on the lower legs; in the second half of the study, when a foaming skin cleanser was introduced and washing with bare hands and washing a cotton towel were compared, the effects of these changes were more obvious in the forearms than the lower legs.The reason that guidance on lathering and washing in the first half of the study only produced a quick improvement in skin score in the lower legs remains unknown; however, our conjecture is that participation in this study itself possibly increased the study participants' consciousness of their lower legs, which are normally less conspicuous but have a higher total skin score than do the forearms, thereby improving study participant adherence to skin care and attentive washing methods.
population.Similar studies in other countries should be conducted to verify whether these interventions are equally effective in other countries and cultures.In conclusion, this study reveals that incorporating appropriate and basic methods into daily body washing for xerotic skin can improve xerotic symptoms and related skin measurements in patients with atopic and asteatotic dermatitis.AUTH O R CO NTR I B UTI O N S Conception and design of the study: Satoshi Takeuchi, Masutaka Furue, and Hiroshi Matsunaka.Recruitment of subjects and acquisition of data: Satoshi Takeuchi.Analysis of data: Satoshi Takeuchi and Yumi Murakami.Drafting of the manuscript: Satoshi Takeuchi.Revising the manuscript critically for important intellectual content: Takeshi Nakahara and Hiroshi Matsunaka.All authors reviewed and edited the manuscript and approved the final version of the manuscript.

Washing guidance (from start of the study to Week 4)
Skin measurements and analysis of stratum corneum.
TA B L E 4a.

Ease of guidance adoption % Easy to adopt Difficult to adopt Neither opinion
Note: Pearson's chi-squared test: p < 0.01. a.