Soap-induced damage to the stratum corneum arises as a result
of elevated proteolytic degradation of corneodesmosomes
S. G. Danby1,*, A. Wigley1, N. Tierney2, K. Martin2, G. Stamatas2, M. J. Cork1
Abstract ID: 2983802
1The
Academic Unit of Dermatology Research, Department of Infection and Immunity, The University of Sheffield Medical School, Sheffield, UK;
2Johnson & Johnson Consumer Companies Inc., Skillman, New Jersey, USA. *Corresponding Author: [email protected]
INTRODUCTION
RESULTS
The use of soap and harsh detergents causes
xerosis and exacerbates atopic dermatitis (AD)1
by a mechanism involving skin barrier
breakdown. How soap facilitates skin barrier
breakdown is not fully understood. The most
damaging soaps and detergents all elevate skinsurface-pH, whereas milder synthetic
surfactants do not. Stratum corneum (SC) pH is
an important regulator of skin barrier
homeostasis, and when elevated increases the
activity of serine proteases involved in
desquamation. Elevated protease activity leads
to accelerated proteolysis of desmoglein 1
(DSG1) and other corneodesmosomal
components responsible for cell-to-cell adhesion
of corneocytes2,3. We hypothesized that, by
modification of skin-surface-pH, the use of soap
exacerbates AD by increasing the rate of
corneodesmosomal proteolysis.
BSL
0.5
4
5
SGD is in receipt of a research fellowship from Johnson & Johnson
Consumer Companies Inc. SGD and MJC have received funding
for investigator-led research from Johnson & Johnson Consumer
Companies Inc.
4
60
8
7
6
5
4
**
5
10
15
24
Chymotrypsin-like activity (nU/µg)
Figure 4: Elevated skin-surface-pH
significantly correlated with elevated
ex vivo stratum corneum
chymotrypsin-like protease activity
(p<0.0001).
6
4
2
*
*
30
10
4
8
12
16
20
**
15
10
5
20
0
4
8
12
16
20
as
w
as
Tape strip number
So
ap
w
o
N
0
Soap wash
No wash
h
h
h
h
as
w
40
20
0
o
25
Soap wash
No wash
50
TEWL (g/m2/h)
Chymotrypsin-like activity (nU/µg)
*
Tape strip number
Figure 5: The effect of a 7 day soap wash regime. Skin-surface-pH (far left) and chymotrypsin-like protease activity
(centre left) were significantly elevated (p=0.01 and p=0.0024 respectively) 12 hours post-final wash. TEWL was
significantly elevated following tape stripping (centre right), the extent of which was dependent on whether soap was
used or not (p<0.05 at TS16 and TS20, identified using a Sidak post-test following a 2-way ANOVA). Skin integrity was
significantly reduced post-wash (far right) (p=0.0051 at TS4 identified using a Sidak post-test following a 2-way ANOVA).
4. DSG1 staining becomes more
peripheral towards the surface of the
skin.
Chymotrypsin-like activity (nU/µg)
DSG1 staining pattern
10
Soap wash
No wash
3
2
1
0.00
0.25
0.50
0.75
5. A peripheral DSG1 staining pattern is associated with
elevated protease activity and decreased skin barrier
function.
1.00
Basal
8
30
Y = 5.716*X - 15.92
Y = 8.700*X - 10.43
r = 0.7660
25
6
TEWL (g/m2/h)
Peripheral 4
4
2
r = 0.8182
20
15
0
-2
2.5
3.0
More uniform
3.5
4.0
Peripheral
Desmoglein 1 staining pattern
SC depth
CONFLICT OF INTEREST
0.5
0
Time post-washing (hours)
Uppermost
We thank all our volunteers for taking part, Les Hunter for
recruitment, and Johnson & Johnson Consumer Companies Inc.
(New Jersey, USA) for providing the funding.
BSL
8
Uniform
ACKNOWLEDGEMENTS
5
Protein removed (µg/cm2)
9
•  DSG1 distribution was determined for samples of SC
removed by tape stripping by staining with anti-DSG1
(Progen Biotechnik, Germany) and Alexa Fluor 488 (Life
Technologies, UK). DSG1 was observed using an
inverted Zeiss LSM 510 NLO confocal microscope.
Subsequent analysis was performed using Image J.
10
2.5
3.0
More uniform
3.5
4.0
Peripheral
Desmoglein 1 staining pattern
Figure 6: DSG1 staining changed from more
uniform in the deeper SC layers to more
peripheral in the upper layers. Following a 7
day soap wash regime the uppermost SC
layer had a more peripheral staining pattern
than unwashed skin (p=0.0317).
Figure 7: Elevated chymotrypsin-like protease activity correlated with a
more peripheral DSG1 staining pattern (p=0.013) on the uppermost SC
layer (left). A 7 day soap wash regime increased TEWL on average by
6.8g/m2/h (p=0.0127) (data not shown). Elevated TEWL correlated with
a more peripheral DSG1 staining pattern (p=0.0058) on the uppermost
SC layer (right).
6. Protease activity does not elevate
if a mild cleanser that does not
increase skin-surface-pH is used.
CONCLUSIONS
Fold change in chymotrypsin-like activity
Meding B, Swanbeck G. Br J Dermatol 1987; 116:627-­‐634. Lundström A, Egelrud T et al. J Invest Dermatol 1990; 94:216-­‐20. Caubet C, Jonca N et al. J Invest Dermatol 2004; 122:1235-­‐44. Fluhr JW, Feingold KR et al. Exp Dermatol 2006; 15:483-­‐92. Voegeli R, Rawlings AV et al. Br J Dermatol 2009; 161:70-­‐7. 6
4
0
r = 0.9675
7
3. Washing skin with soap for 7 days damages the skin barrier; resulting in elevated skin-surface-pH,
elevated chymotrypsin-like protease activity, and decreased SC integrity.
•  Chymotrypsin-like and caseinolytic protease activity were
determined for samples of SC removed by tape stripping
based on a previously published method5.
1. 
2. 
3. 
4. 
5. 
Soap
wash
10
24
Y = 0.1973*X + 4.661
Figure 3: The effect of a single wash with soap compared to washing with water
alone. Skin-surface-pH (left) and chymotrypsin-like protease activity (right) were
significantly elevated for at least 4 hours following washing, the extent of which
was dependent on whether soap was used or not. Asterisks indicate a significant
difference (p<0.05) identified using a Sidak post-test following a 2-way ANOVA.
•  Skin barrier function was determined by measuring TEWL
using an AquaFlux TEWL machine (Biox, UK)4.
REFERENCES
Water
wash
*
Time post-washing (hours)
•  Skin-surface-pH was measured using a Skin-pH-meter
(C&K, Germany).
Figure 2: DSG1 staining was scored on a scale
of 1 (uniform) to 4 (peripheral) from the
uppermost to the basal SC layer. The basal SC
layer was determined when no more
corneocytes were detected by infrared
densitometry following tape stripping.
8
*
Skin-surface-pH
5
N
Three cohorts of volunteers were recruited between the
ages of 18-60, with a Fitzpatrick skin type I-III and no history
of atopy. In the first cohort, 10 participants washed one
forearm with traditional alkyl carboxylate soap (Imperial
Leather® original bar soap) and water and the other with
water alone once. The biophysical and biological properties
of the skin were assessed before and at set time points postwashing. In the second cohort, 12 participants washed one
forearm with soap and water and the other with a liquid
cleanser (Johnson’s® baby head-to-toe® wash) once. The
biophysical and biological properties of the skin were
measured before and at set time points post-washing. In the
third cohort, 5 participants repeated the soap wash 3 times
per day for 7 days on one forearm. The biophysical and
biological properties of the skin were measured 12 hours
post-final wash. The following assessments were made:
6
3
Skin-surface-pH
METHODS
Soap
wash
4
Figure 1: SC cell-cell adhesion of corneocytes
Aim: To determine the effect of washing
with soap compared to water alone,
and a liquid cleanser containing a
synthetic detergent, on the structure of
the skin barrier.
*
Chymotrypsin-like activity (nU/µg)
Skin-surface-pH
7
Water
wash
as
Cornified envelope Proteases -­‐ Chymotrypsin-­‐like -­‐ Trypsin-­‐like -­‐ CaseinolyZc *
w
Corneocyte Lipid lamellae 15
ap
Corneocyte Desmoglein 1 8
So
Corneodesmosome 2. Elevated skin-surface-pH
is associated with elevated
protease activity.
1. Washing skin with soap once significantly increases skinsurface-pH and chymotrypsin-like protease activity for more than 4
hours compared to washing with water alone.
7
6
5
***
***
***
Cleanser
wash
Soap
wash
4
•  Washing with soap elevates chymotrypsin-like protease
activity, by modifying skin-surface-pH.
•  Elevated protease activity was associated with reduced
inter-corneocyte cohesion/SC integrity.
•  The reduction in SC integrity could be explained by a
decrease in the number of central, but not peripheral,
corneodesmosomal junctions on the surface of
corneocytes.
3
•  A peripheral pattern of corneodesmosomal staining was
correlated with reduced skin barrier function.
2
1
0
0.25
0.5
4
24
Time post-washing (hours)
Figure 8: The effect of a single wash with
soap compared to a mild cleanser on
protease activity (*p<0.001). Skin-surface-pH
remained within the normal range using the
cleanser, but elevated following the soap use.
•  Peripheral corneodesmosomes appear to be protected
from soap-induced increases in chymotrypsin-like protease
activity. Tight junctions have been proposed to protect
peripheral corneodesmosomes from cleavage.
•  Washing with a mild liquid cleanser optimized for babies did
not affect SC chymotrypsin-like protease activity, and
therefore may help protect against skin barrier breakdown
and development of AD.