British ]ounml of Dermatology 1997; 1 i6: 966-967.

Normal recovery of the stratum corneum barrier functionfollowing damage induced by tape stripping in patients withatopic dermatitis

M.TANAKA. Y.X.ZHEN AND H.TAGAMIDepartment oj Dermatology. Tohoku University School of Medicine. Aobakii Seirijo-nuichi I-I. Sendai 9 8 0 - 7 7 . japan

Accepted for publication 19 December 1996

Summary Patients with atopic dermatitis (AD) constantly inflict mechanical damage to their skin by scratchinginduced by pruritus. On excoriated lesions of the cheek we found exceedingly high levels oftransepidermal water loss (TEWL) as compared to those in the normal skin of healthy subjects.However, it is not clear whether the skin of patients with AD also shows an abnormally slow recoveryafter mechanical damage. We compared the recovery of the barrier function of the stratum corneum(SC). after its complete removal by tape stripping, in patients with AD and age-matched healthycontrol subjects. On the normal-looking skin of the flexor forearm, we found no difference in therecovery process of the water barrier function of the SC between the two groups. This suggests thatability to reconstruct SC barrier function after mechanical damage is not impaired in AD patients.

Recent analyses of the stratum corneum (SC) in patientswith atopic dermatitis (AD) have revealed various typesof functional impairment of the SC even in clinicallyuninvolved xerotic skin outside the dermatitic areas.'"^Non-lesional skin of patients with AD has been reportedto show more severe damage and slower recovery ofthe SC barrier function following irritation with sodiumlauryl sulphate (SLS). the most widely utilized surfactantfor studying irritation, than that of control subjects."'*'Mechanical removal of the SC by tape stripping caninduce reproducible damage to the SC.

The time course of recovery of transepidermal waterloss (TEWL) values, as well as water-holding capacity ofthe SC, after complete tape stripping has been studied innormal healthy subjects.' Within the first 2 days therewas about 80% recovery of TEWL values and. in normalsubjects, complete recovery of SC function was observed14 days after tape strippitig. In the present study wehave examined whether patients with AD, whose skin iscovered with numerous scratch marks due to incessantpruritus, show any abnormal reaction to the mechani-cal damage induced by tape stripping as compared withage-matched healthy control subjects.

Materials and methods

Six patients (mean age ± SEM, 29 ± 3 years, five malesand one female) with AD and 12 age-matched healthycontrol subjects (mean age 30 ± 1 years, four males and

eight fetnales) were included in this study. Clinically,their disease activity was moderate according to thecriteria of Hanifin and Rajka.^ We used the cheek andthe mid-portion of the volar aspect of the forearms of thesubjects for the experiments. In those with AD, non-inflamed uninvolved skin areas were chosen for the tapestripping study."* The patients received topical steroidtherapy only for areas of active dermatitis, avoiding theforearm test sites. The SC of the fiexor forearm skin wascompletely removed by stripping with adhesive cello-phane tape. All measurements were conducted at roomtemperature (18-20 °C) and the relative humidityvaried between 20 and 30% in the months of Januaryand February. TEWL was determined with a skin eva-porative water recorder (Evaporimeter, Servo Med,Stockholm. Sweden).^ Measurements of TEWL in theexcoriated skin of patients with AD were performed onthe cheek of the face and also on the tape-stripped sites,over the subsequent 2 weeks, and also on the adjacentnormal control skin.

Results

The mean value ± SEM of TEWL for the excoriated lesions(7O±7g/m") on the cheek was signiticantly higher(P<0-01, Student's Mest) than that of the adjacentnon-erosive lesions whose mean (38±10g/m^) wasstill remarkably high when compared to that of thecheek of healthy controls (10 ± 2 g/ni^}.

966 1997 British Association of Dermatologists

STRATUM CORNEUM BARRIER FUNCTION 967

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Figure 1. Comparison of recovery after lape stripping of the stratumcurneuni function, estimated by transepidermal water loss (TEW'L|levels, bflween atopic dermatitis (Al) stripped! patients and healthycontrols (HC strippedl. Vertical bars represent standard errors of tbemean. Broken lines represent TEWL values of non-slripped controlsites (AD control. HC control). There were no significant differences inthe TEWL levels between the two groups at each point.

Increased TEWL levels, similar lo those noted atthe erosive lesions of the AD patients, were observedimmediately after complete removal of the SC from theflexor forearm skin of normal subjects or from theunaffected skin of AD patients, by adhesive-tape strip-ping. This was due to direct exposure of the moist viableepidermis. With the formation of crusty scales, thesevalues recovered to be H()~9{)% of the normal TEWLlevels within 3 days. From the second to the sixth day.patients with AD tended to show earlier recovery ofTEWL levels than controls, although this was notstatistically significant (Fig. 1. Students t-test). Theforearm skin of AD patients examined in this presentstudy was not xerotic and looked the same as that of thecontrols. The TEWL levels of the adjacent normal skin inthe AD subjects did not differ significantly from those ofnormal controls (Fig. 1).

Discussion

The pruritic skin of patients with AD commonly showsmultiple excoriated lesions. In this study we found thatthe erosive facial lesions of patients with AD showenormously high TEWL values compared to healthycontrols. The values are comparable to those seenover a warm water surface. Excoriated skin in patientswith AD is thought to allow easy passage of certain large

molecular weight environmental allergens. The TEWLvalues of excoriated lesions in AD patients were as highas those of sites subjected to complete tape stripping.Unlike in SLS-irritated skin.^ we found that the recoveryof the SC damaged by tape stripping was not impaired orwas. in fact, rather faster in patients with AD than inhealthy control subjects. From these results, we believethat the ability for recovery of damaged SC in patientswith AD is not impaired as long as the skin clinicallylooks normal.

Atopic xerosis. the dry skin of patients with AD.shows impairment of various SC functions, probablyreflecting increased epidermal proliferation due to a lowlevel ongoing dermatitis."* Matiy authors describe^"**abnormally increased TEWL in such skin. Patientswith AD are reported to react more severely to SLSthan do controls. They show higher TEWL values soonafter the application of SLS and slower recovery at 1week later than normal controls.^ In contrast, we didnot find any specific difference in the response tomechanical irritation in our present study. This discre-pancy may stem from the difference in skin reactivity tosurfactant irritation and physical injury. The mildinflammatory infiltration in skin affected by atopicxerosis seems to mean that it will react much more tochemical irritation than to physical insults, We considerthat the unaffected skin in our patients was totallynormal, as its barrier function was not inferior to thatin healthy controls.

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associated with atopic eczema. Br / Dcnnatol 1*JS(): lOJ: 249-Sf^.2 Werner Y, Lindberg M. Transt'pidermal water loss in dry and

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5 Nassif A. Chan SC. Slurrs F] ct al. Abnormal skin irritancy in atopicdermatitis and in atopy without dermatitis. Arch Dermalal 1994;130: 1402-7.

6 Tupker RA. Coenraads PJ, Fidler V et al. Irritant susceptibility andweal and flare reactions to bioactive agents in atopic dermatitis. I.Influence of disease severity. Hr j Dermatol 1995; U J : J'i8-fi4.

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1997 British Association of Dermatologists. British journal of Dermatoloyij. 136. 966-9f)7