Introduction: Diesel particulate matter (DPM) emitted from diesel engines is a major source of air pollutants. DPM is composed of elemental carbon, which adsorbs organic compounds including toxic polycyclic aromatic hydrocarbons (PAHs). The skin, as well as airways, is directly exposed to DPM, and association of atopic dermatitis, psoriasis flares, and premature skin aging with air pollutant levels has been documented. In skin, the permeation of DPM and DPM-adsorbed compounds is primarily blocked by the epidermal permeability barrier deployed in the stratum corneum. Depending upon the integrity of this barrier, certain amounts of DPM and DPM-adsorbed compounds can permeate into the skin. However, this permeation into human skin has not been completely elucidated. Methods: We assessed the permeation of PAHs (adsorbed to DPM) into skin using ex vivo normal (barrier-competent) organ-cultured human skin after application of DPM. Two major PAHs, 2-methylnaphthalene and triphenylene, and a carcinogenic PAH, benzo(a)pyrene, all found in DPM, were measured in the epidermis and dermis using liquid chromatography electrospray ionization tandem mass spectrometry. In addition, we investigated whether a topical formulation can attenuate the permeation of DPM into skin. Results: 2-Methylnaphthalene, triphenylene, and benzo(a)pyrene were recovered from the epidermis. Although these PAHs were also detected in the dermis after DPM application, these PAH levels were significantly lower than those found in the epidermis. We also demonstrated that a topical formulation that has the ability to form more uniform membrane structures can significantly suppress the permeation of PAHs adsorbed to DPM into the skin. Conclusion: Toxic compounds adsorbed by DPM can permeate even barrier-competent skin. Hence, barrier-compromised skin, such as in atopic dermatitis, psoriasis, and xerosis, is even more vulnerable to air pollutants. A properly formulated topical mixture that forms certain membrane structures on the skin surface can effectively prevent permeation of exogenous substances, including DPM, into skin.

1.
Wang
HL
,
Sun
J
,
Qian
ZM
,
Gong
YQ
,
Zhong
JB
,
Yang
RD
, et al
.
Association between air pollution and atopic dermatitis in Guangzhou, China: modification by age and season
.
Br J Dermatol
.
2021
;
184
(
6
):
1068
76
.
2.
Bellinato
F
,
Adami
G
,
Vaienti
S
,
Benini
C
,
Gatti
D
,
Idolazzi
L
, et al
.
Association between short-term exposure to environmental air pollution and psoriasis flare
.
JAMA Dermatol
.
2022
;
158
(
4
):
375
81
.
3.
Schikowski
T
,
Huls
A
.
Air pollution and skin aging
.
Curr Environ Health Rep
.
2020
;
7
(
1
):
58
64
.
4.
Farahani
VJ
,
Pirhadi
M
,
Sioutas
C
.
Are standardized diesel exhaust particles (DEP) representative of ambient particles in air pollution toxicological studies
.
Sci Total Environ
.
2021
;
788
:
147854
.
5.
Hoskin
R
,
Pambianchi
E
,
Pecorelli
A
,
Grace
M
,
Therrien
JP
,
Valacchi
G
, et al
.
Novel spray dried algae-rosemary particles attenuate pollution-induced skin damage
.
Molecules
.
2021
;
26
(
13
):
3781
.
6.
Uchida
Y
,
Park
K
.
Ceramides in skin health and disease: an update
.
Am J Clin Dermatol
.
2021
;
22
(
6
):
853
66
.
7.
Suzuki
M
,
Ohno
Y
,
Kihara
A
.
Whole picture of human stratum corneum ceramides, including the chain-length diversity of long-chain bases
.
J Lipid Res
.
2022
;
63
(
7
):
100235
.
8.
Loden
M
.
Role of topical emollients and moisturizers in the treatment of dry skin barrier disorders
.
Am J Clin Dermatol
.
2003
;
4
(
11
):
771
88
.
9.
Loden
M
.
Effect of moisturizers on epidermal barrier function
.
Clin Dermatol
.
2012
;
30
(
3
):
286
96
.
10.
Chaudhary
M
,
Khan
A
,
Gupta
M
.
Skin ageing: pathophysiology and current market treatment approaches
.
Curr Aging Sci
.
2020
;
13
(
1
):
22
30
.
11.
Danso
MO
,
Berkers
T
,
Mieremet
A
,
Hausil
F
,
Bouwstra
JA
.
An ex vivo human skin model for studying skin barrier repair
.
Exp Dermatol
.
2015
;
24
(
1
):
48
54
.
12.
Neil
JE
,
Brown
MB
,
Williams
AC
.
Human skin explant model for the investigation of topical therapeutics
.
Sci Rep
.
2020
;
10
(
1
):
21192
.
13.
Obata
Y
,
Takahashia
S
,
Ishida
K
,
Takayama
K
.
Evaluation of the structure and barrier function of a skin care formulation containing optically active ceramide 2 and cholesterol
.
Asian J Pharm Sci
.
2009
;
4
(
5
):
292
9
.
14.
Ishida
K
,
Obata
Y
,
Akagi
C
,
Onuki
Y
,
Takayama
K
.
Practical syntheses of D-erythro- and L-threo-ceramide [NDS] and difference in contribution of each isomer in microstructure of stratum corneum intercellular lipids
.
J Drug Deliv Sci Technol
.
2014
;
24
(
6
):
689
93
.
15.
Uchida
Y
,
Celli
A
.
A method to investigate the epidermal permeability barrier in vitro
.
Methods Mol Biol
.
2020
;
2154
:
73
90
.
16.
Bourgart
E
,
Barbeau
D
,
Marques
M
,
von Koschembahr
A
,
Beal
D
,
Persoons
R
, et al
.
A realistic human skin model to study benzo[a]pyrene cutaneous absorption in order to determine the most relevant biomarker for carcinogenic exposure
.
Arch Toxicol
.
2019
;
93
(
1
):
81
93
.
17.
Nakazawa
H
,
Ohta
N
,
Hatta
I
.
A possible regulation mechanism of water content in human stratum corneum via intercellular lipid matrix
.
Chem Phys Lipids
.
2012
;
165
(
2
):
238
43
.
18.
Ohnari
H
,
Naru
E
,
Sakata
O
,
Obata
Y
.
Distribution of domains formed by lateral packing of intercellular lipid in the stratum corneum
.
Chem Pharm Bull
.
2023
;
71
(
1
):
31
40
.
19.
De Luca
C
,
Valacchi
G
.
Surface lipids as multifunctional mediators of skin responses to environmental stimuli
.
Mediators Inflamm
.
2010
;
2010
:
321494
.
20.
Sheu
HM
,
Chao
SC
,
Wong
TW
,
Yu-Yun Lee
J
,
Tsai
JC
.
Human skin surface lipid film: an ultrastructural study and interaction with corneocytes and intercellular lipid lamellae of the stratum corneum
.
Br J Dermatol
.
1999
;
140
(
3
):
385
91
.
21.
Cecchi
L
,
D’Amato
G
,
Annesi-Maesano
I
.
External exposome and allergic respiratory and skin diseases
.
J Allergy Clin Immunol
.
2018
;
141
(
3
):
846
57
.
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