Analysis of Components of the CD14/TLR System on Leukocytes of Patients with Atopic Dermatitis

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Abstract
Atopic dermatitis (AD) is frequently associated with skin infections that may be a consequence of an impaired function of the innate immune response. Conversely, the frequent bacterial colonization may also influence the systemic immune reactions, including the Toll-like receptor (TLR) system, through the translocation of bacterial components into the circulation. Therefore, we characterized phenotypic and functional properties of the TLR system in patients with extrinsic and intrinsic AD. The absolute number of surface CD14, TLR2, TLR4 and CD180 and the CD14-mediated uptake of bodipy-labeled endotoxin and bacteria by whole blood leukocytes was studied by flow cytometry. We measured the serum soluble CD14 concentration by an inhibitory flow cytometric method. We observed a significant overexpression of TLR2 and TLR4 on monocytes, TLR2 and CD14 on granulocytes and CD180 on lymphocytes of intrinsic AD patients compared to healthy controls. The serum soluble CD14 was not different in the intrinsic AD patients, while it was diminished in the extrinsic AD group compared to the controls. The endotoxin and bacterium uptake showed no differences. The observed upregulation of CD14, TLR2, TLR4 and CD180 on peripheral leukocytes seems to be rather a consequence than the cause of the repeated bacterial infections in AD.