経表皮水分蒸散量(TEWL)の上昇は犬の皮膚バリア機能破壊を反映する

誌名誌名 The journal of veterinary medical science

ISSNISSN 09167250

著者著者

島田, 健一郎吉原, 徹山本, 昌彦ほか4名,

巻/号巻/号 70巻8号

掲載ページ掲載ページ p. 841-843

発行年月発行年月 2008年8月

農林水産省 農林水産技術会議事務局筑波産学連携支援センターTsukuba Business-Academia Cooperation Support Center, Agriculture, Forestry and Fisheries Research CouncilSecretariat

NOTE Internal Medicine

Transepidermal Water Loss (TEWL) Reflects Skin Barrier Function ofDog

Kenichiro SHIMADA1)， Toru YOSHIHARA2)， Masahiko YAMA加tOT011， Katsuhiko KONN01)， Yasuyuki MOM0I1)，

Koji NISHIFUnl) and Toshiroh IWASAKI1)

/JDepartment of Veterinary Inlernal Medicine， Faculηof Agriculture， To勾oUniversiηof Agriculture & Technology， 3-5--8 Saiwai， Fuchu， To旬。 183--8509and 2) Kao Corporation， 2ー1-3Bun知 ，Sumida，To勾0，Japan

(Received 29 January 2008/Accept巴d15 April 2008)

ABSTRA口 Thecorrelation between skin barrier function and transepiderrnal water loss (TEWL) was巴valuatedin dogs. Stratum corneum (SC) of 10 hea1thy dogs was remov巴dby tape stripping (TS)， which decreased出ecorn巴allay巴rto allow for perrneation of fluorescent dy巴 intoskin. TEWL of damaged skin was measured with the c1osed-ch創nber-typeTEWL analyzer， CC-01. The frequency of TS was directly related to th巴d巴creaseof SC and the increased p巴rmeationof fluorescent dye， and TEWL increased with increasing impairrn巴ntof skin barrier function. The results suggest that increased TEWL reflects impaired canine skin barrier function KEY WORDS: canine skin， skin barrier function， transepidermal water loss.

The skin functions as an interactive wall of mammalian

body， controlling egress of water and suppressing ingress of environmental and microbial agents， thereby preventing skin diseases [3]. Therefore， the maintenance of skin barrier function is critical for the住eatmentof skin diseases in mam-mals.

Transepidermal water loss (TEWL) is de白nedas the vol-ume of water that passes from inside to outside of the body through the epidermallayer. TEWL measurement has been used to evaluate skin barrier function in human [1， 5， 8]， and an increase in TEWL has been repo巾 dto reflect impair-ment of skin barrier function [2]， i.e.， high TEWL suggests low skin barrier function. In addition， in human， a number of studies have suggested that high TEWL is associated in various skin diseases， including atopic dermatitis， psoriasis，

contact dermatitis， and ichthyosis [4， 10， 11， 14]. Thus，

TEWL is thought to be a us巴fulP訂 ameterthat characteriz巴sskin barrier function in human.

Many skin disorders are suggested to be associated with skin barrier function in dogs [7]. However， the relationship between skin disease and the barrier function is not w巴11analyzed because of paucity of studies on出eTEWL va1ue in normal and damaged canine skin. In this study， we eval-uated whether TEWL could reflect impaired canine skin barrier function or not.

Ten healthy dogs (8 crossbred dogs and 2 b巴agles，age range 7-13 years， 1 female， 3 sterilized females， and 4 neu-tered males) were enrolled in出isstudy. All anima1s were fed on the same food and kept in an air-conditioned room. Two different anatomical areas， lumbar skin and inguinal skin， were used for TEWL measurement. Hair on both areas of each dog was clipped before measurement. M巴asure-ments were performed at 23-250C and 45-65% relative

* CORRESPONDENCE TO: IWAsAKI， T.， Department ofVeterinary Inter-nal Medicine， Faculty of Agriculture， Tokyo University of Agrト

culture & Technology， 3-5-8 Saiwai， Fuchu， Tokyo 183-8509， Japan. e-mail: bpag2180@cc.tuat.ac.jp

J. Vet. Med. Sci. 70(8): 841-843，2008

humidity. AlI dogs were acclimated at least 30 min to th巴measurement conditions. AlI experiments were performed in accordance with the guidelines of anima1 research com-mittee in Tokyo University of Agriculture and Technology.

Tape stripping (TS) is a well-known method to artificially damage the stratum corneum (SC) [9， 12]. TS was per-formed on the left and right sides of lumbar skin and inguinal skin of five of ten dogs， using adhesive cellophane tape (Nichiban， Tokyo， Japan). The tape-stripped areas

were divided into five parts， and skin of each part was tape-stripped 0， 5， 10， 15 or 20 times， respectively. After TS，

TEWL in each area was measur巴dthree times with a closed-chamber-type TEWL analyzer (CC-Ol， Kao Corporation， Japan) [15]. TEWL was expressed as mean :t SD

Skin was sampled from each of the five tape-stripped areas with 6 mm biopsy trepan. Then， fluor.巴sc巴ntdye was applied to tape-stripped areas of the other 5 dogs in order to visualize skin damage. Fluorescence dye (10%， A1con， Japan) was measured 0.05 ml and poured into出巴paperdisc and held to the skin by Finn chamber (Epitest， Helsinki， Fin-land). Thirty min after application，出epatch test area was washed with physiological sa1ine solution， and permeation of fluorescent dye into the skin was observed with Wood's lamp in a darkroom.

Figure 1 shows the histopathological findings and percu-taneous permeation of fluorescent dye into lumbar skin of a representative dog. The non-stripped area had more than 10 SCs， but after stripping 5 times， more出anhalf of出eSC was removed. Only a few SCs were left on the epidermis after stripping 10 times， and permeation of the fluorescent dye was apparently visible. Moreover， stripping 15 times completely removed the SC， and the extent of permeation of the fluorescent dye was the same as that of the area stripp巴d10 times. These findings indicate that similar to human skin， TS of canine skin impair巴dskin barrier function to allow for permeation of fluorescent dye into the skin

Figur巴2shows the relationship between TEWL and fre-quency of tape stripping in 10 dogs. In the lumbar region，

842 K. SHIMADA ET AL

Fig. 1. HistopathologicaI findings and permeation of fluorescent dye after tape stripping in lumbar skin. According to tape stripping fre-qu巴ncy，canine skin stratum corneum graduaIly decreased and percutaneous permeation of fluorescent dye was accelerated. 0， non S仕ippedarea. 5， 10， 15， and 20， fr.巴quencyof tap巴stripping.

200 制ド

• Lumbar

175

口 Ingui na I

"""' 150 '-...c: (n = 10)

N 125 ホ p < 0.05 ε 、b¥o

'---" 100 ー」室主LU

ト 75

50

25

。O 5 10 15 20 FreCI-.Jenαof tape stripping

Fig. 2. Relationship between TEWL and frequency of tape stripping. TEWL is significantly increased in lumbar skin and inguinal skin when fr，巴quencyof tape stripping was increased， compared wi出 non-strippedarea (One-factor ANOVA， P<0.05). There is a positive correlation between TEWL and frequency of TS in bo出areas(Spearman' s rank correlation， P<0.05).

TEWL in non tape-stripped area was 20.59:t 5.51 (g/m勾hr)，

but after stripping five times， it increased to 28.17:t 7.47 (g/

m2・hr). After stripping 10 times， it incr巴asedto 44.87士

24.02 (g/m2・hr)，and after stripping 15 times， it was 66.61 :t 24.94 (g/m2ohr). TEWL was 87.58 :t 30.59 (g/m2ohr) after

stripping 20 times. In the inguinal region， TEWL in non

tape-stripped area was 20.17 :t 3.60 (g/m2・hr)，but increased to 33.37 :t 8.53 (g/m2ohr) after stripping 10 times. It was

63.94:t 19.78 (g/m2ohr) after stripping 15 times， and increased to 129.05 :t 64.11 (g/m2ohr) after stripping 20

times. The mean TEWL values increas巴dwith the fre-

quency of stripping and were significantly high巴rthan those

in the non-stripped area on both lumbar skin and inguinal skin (One-factor ANOV A， Pく0.05).And also， there is a

positive correlation between TEWL and frequency of TS in

both areas (Spearman's rank correlation， P<0.05). Th巴 purposeof this study is (0 evaluate the relationship

between TEWL and impaired skin in dogs. There are some

studies of TEWL in canine skin， but most of them used open-chamber-type instruments [6， 13]. We measured TEWL with a cIosed-chamber-type instrum巴nt，which is

considered to be better than the open chamber type because

it minimizes the effects of a reIative humidity and move-ment of dogs [15]

We found that the increased frequency of tape stripping

induc巴dhigh TEWL value. Mean TEWL was higher in the area stripped 10 times than in the non-stripped area， and flu

orescent dye permeated into the skin as the SC was dam-

aged. Since fluorescent dye does not permeate into the skin

when skin barrier function is intact， as observed in the non-

stripped area， the permeation of fluorescent dye is an indica-tion that skin barrier function was impaired. Taken

together， it is conceived that TEWL and impairment of skin barrier function may have a positive correlation.

In concIusion， the relationship between TEWL and dam-

aged skin in dogs was cIarified. TEWL measurement

enables us to evaluate canine skin barrier function quantita-tively. The advantages presented by出isnon-invasive pro-

cedure， quantificating of skin barrier state will give us new insights into skin biology and the pathogenesis and treat-ment of skin diseases.

TRANSEPlDERMAL W ATER LOSS IN CANINE SK別 843

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