A study of matrix metalloproteinase expression and activity in atopic dermatitis using a novel skin wash sampling assay for functional biomarker analysis.
BACKGROUND
Atopic dermatitis (AD) is a chronic inflammatory skin condition that is characterized by a defective skin barrier. Despite the well-recognized role of proteases in skin barrier maintenance, relatively little is known of the contribution made by matrix metalloproteinases (MMPs) to the inflammatory process in AD.


OBJECTIVE
To test a simple, novel ex vivo bioassay technique in an analysis of the MMPs present in wash samples taken from the skin surface of patients with AD.


METHODS
Saline wash samples were collected from eczematous and unaffected areas of the skin of patients with AD and from the skin of normal controls. Wash samples were analysed for their MMP content using a functional peptide cleavage assay, gelatin zymography and an antibody array.


RESULTS
Using a functional substrate cleavage assay, skin wash samples from AD lesions were shown to contain 10- to 24-fold more MMP activity than those from normal control skin (P < 0.02) and fivefold more than those from unaffected AD skin (P < 0.05); this activity was inhibited by a broad-spectrum MMP inhibitor Ro 31-9790. Gelatin zymography and antibody array analysis revealed substantial levels of MMP-8 (neutrophil collagenase) and MMP-9 (92-kDa gelatinase) in AD skin wash samples as well as lower levels of MMP-10 (stromelysin 2) and tissue inhibitor of metalloproteinases (TIMP)-1 and TIMP-2; low levels of MMP-1 (fibroblast collagenase), MMP-3 (stromelysin 1) and TIMP-4 were also detected.


CONCLUSIONS
A simple skin wash technique suitable for the quantitative and functional analysis of biomolecules in AD is described. Using this method we show that MMPs, and in particular MMP-8 and MMP-9, represent an important potential component of the pathology of AD. The method is expected to prove useful in advancing our understanding of AD and in identifying biomarkers for the evaluation of new therapies.
Harper
J I
JI
Department of Paediatric Dermatology, Great Ormond Street Hospital for Children, London WC1N 3JH, U.K. harpej@gosh.nhs.uk
Godwin
H
H
Green
A
A
Wilkes
L E
LE
Holden
N J
NJ
Moffatt
M
M
Cookson
W O
WO
Layton
G
G
Chandler
S
S
D000293:Adolescent; D015415:Biomarkers / Q000032:analysis / Q000378:metabolism; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D003876:Dermatitis, Atopic / Q000378:metabolism*; D006801:Humans; D020782:Matrix Metalloproteinases / Q000032:analysis / Q000378:metabolism*; D012720:Severity of Illness Index; D012867:Skin / Q000378:metabolism* / Q000473:pathology; D012882:Skin Tests / Q000379:methods; D019714:Tissue Inhibitor of Metalloproteinases / Q000032:analysis / Q000378:metabolism
D015415:Biomarkers; D019714:Tissue Inhibitor of Metalloproteinases; D020782:Matrix Metalloproteinases