Early-onset pediatric atopic dermatitis is TH2 but also TH17 polarized in skin.
Atopic dermatitis (AD) affects 15% to 25% of children and 4% to 7% of adults. Paradigm-shifting discoveries about AD have been based on adult biomarkers, reflecting decades of disease activity, although 85% of cases begin by 5 years. Blood phenotyping shows only TH2 skewing in patients with early-onset pediatric AD, but alterations in early pediatric skin lesions are unknown, limiting advancement of targeted therapies.



We sought to characterize the early pediatric AD skin phenotype and its differences from pediatric control subjects and adults with AD.



Using immunohistochemistry and quantitative real-time PCR, we assessed biopsy specimens from 19 children with AD younger than 5 years within 6 months of disease onset in comparison with adults with AD or psoriasis and pediatric and adult control subjects.



In lesional skin children showed comparable or greater epidermal hyperplasia (thickness and keratin 16) and cellular infiltration (CD3+, CD11c+, and FcεRI+) than adults with AD. Similar to adults, strong activation of the TH2 (IL-13, IL-31, and CCL17) and TH22 (IL-22 and S100As) axes and some TH1 skewing (IFN-γ and CXCL10) were present. Children showed significantly higher induction of TH17-related cytokines and antimicrobials (IL-17A, IL-19, CCL20, LL37, and peptidase inhibitor 3/elafin), TH9/IL-9, IL-33, and innate markers (IL-8) than adults (P < .02). Despite the characteristic downregulation in adult patients with AD, filaggrin expression was similar in children with AD and healthy children. Nonlesional skin in pediatric patients with AD showed higher levels of inflammation (particularly IL-17A and the related molecules IL-19 and LL37) and epidermal proliferation (keratin 16 and S100As) markers (P < .001).



The skin phenotype of new-onset pediatric AD is substantially different from that of adult AD. Although excess TH2 activation characterizes both, TH9 and TH17 are highly activated at disease initiation. Increases in IL-19 levels might link TH2 and TH17 activation.
Department of Dermatology and Laboratory for Inflammatory Skin Diseases, Icahn School of Medicine at Mount Sinai, New York, NY; Laboratory for Investigative Dermatology, Rockefeller University, New York, NY.
Hitokazu
H
Esaki
Laboratory for Investigative Dermatology, Rockefeller University, New York, NY.
Patrick M
PM
Brunner
Department of Dermatology and Laboratory for Inflammatory Skin Diseases, Icahn School of Medicine at Mount Sinai, New York, NY.
Yael
Y
Renert-Yuval
Laboratory for Investigative Dermatology, Rockefeller University, New York, NY.
Tali
T
Czarnowicki
Department of Dermatology, Northwestern University Feinberg School of Medicine, Chicago, Ill.
Thy
T
Huynh
Department of Dermatology, Northwestern University Feinberg School of Medicine, Chicago, Ill.
Gary
G
Tran
Department of Dermatology, Northwestern University Feinberg School of Medicine, Chicago, Ill.
Sarah
S
Lyon
Department of Dermatology, Northwestern University Feinberg School of Medicine, Chicago, Ill.
Giselle
G
Rodriguez
Department of Dermatology, Northwestern University Feinberg School of Medicine, Chicago, Ill.
Supriya
S
Immaneni
NorthShore University HealthSystem, University of Chicago Pritzker School of Medicine, Northbrook, Ill.
Donald B
DB
Johnson
NorthShore University HealthSystem, University of Chicago Pritzker School of Medicine, Northbrook, Ill.
Bruce
B
Bauer
Laboratory for Investigative Dermatology, Rockefeller University, New York, NY.
Judilyn
J
Fuentes-Duculan
Laboratory for Investigative Dermatology, Rockefeller University, New York, NY.
Xiuzhong
X
Zheng
Department of Dermatology and Laboratory for Inflammatory Skin Diseases, Icahn School of Medicine at Mount Sinai, New York, NY.
Xiangyu
X
Peng
Department of Dermatology and Laboratory for Inflammatory Skin Diseases, Icahn School of Medicine at Mount Sinai, New York, NY.
Yeriel D
YD
Estrada
Department of Dermatology and Laboratory for Inflammatory Skin Diseases, Icahn School of Medicine at Mount Sinai, New York, NY.
Hui
H
Xu
Division of Biology and Biomedical Sciences, Washington University, St Louis, Mo.
Christina
C
de Guzman Strong
Department of Dermatology and Laboratory for Inflammatory Skin Diseases, Icahn School of Medicine at Mount Sinai, New York, NY; Laboratory for Investigative Dermatology, Rockefeller University, New York, NY; Department of Population Health Science and Policy, Icahn School of Medicine at Mount Sinai, New York, NY; Department of Genetics and Genomics Science, Icahn Institute for Genomics and Multiscale Biology, New York, NY.
Mayte
M
Suárez-Fariñas
Laboratory for Investigative Dermatology, Rockefeller University, New York, NY.
James G
JG
Krueger
Department of Dermatology, Northwestern University Feinberg School of Medicine, Chicago, Ill.
Amy S
AS
Paller
Department of Dermatology and Laboratory for Inflammatory Skin Diseases, Icahn School of Medicine at Mount Sinai, New York, NY; Laboratory for Investigative Dermatology, Rockefeller University, New York, NY. Electronic address: Emma.Guttman@mountsinai.org.
Emma
E
Guttman-Yassky
D000328:Adult; D000367:Age Factors; D000368:Aged; D002675:Child, Preschool; D016207:Cytokines / Q000378:metabolism; D003876:Dermatitis, Atopic / Q000276:immunology / Q000473:pathology*; D004485:Eczema / Q000276:immunology / Q000473:pathology*; D005260:Female; D000091344:Filaggrin Proteins; D006630:Hispanic or Latino; D006801:Humans; D007223:Infant; D008297:Male; D008875:Middle Aged; D011565:Psoriasis / Q000276:immunology / Q000473:pathology*; D012867:Skin / Q000473:pathology*; D058504:Th17 Cells / Q000276:immunology*; D018418:Th2 Cells / Q000276:immunology*; D014481:United States
D016207:Cytokines; C000717249:FLG protein, human; D000091344:Filaggrin Proteins
Atopic dermatitis; IL-17; IL-19; T(H)17; T(H)2; T(H)9; adult; antimicrobials; pediatric; skin