Cutting edge: Loss of TLR2, TLR4, and TLR5 on Langerhans cells abolishes bacterial recognition

AMG van der Aar, RMR Sylva-Steenland… - The journal of …, 2007 - journals.aai.org
AMG van der Aar, RMR Sylva-Steenland, JD Bos, ML Kapsenberg, EC de Jong
The journal of immunology, 2007journals.aai.org
It is unknown whether closely related epidermal dendritic cells, Langerhans cells (LCs), and
dermal dendritic cells (DDCs) have unique functions. In this study, we show that human
DDCs have a broad TLR expression profile, whereas human LCs have a selective impaired
expression of cell surface TLR2, TLR4, and TLR5, all involved in bacterial recognition. This
distinct TLR expression profile is acquired during the TGF-β1-driven development of LCs in
vitro. Consequently, and in contrast to DDCs, LCs weakly respond to bacterial TLR2, TLR4 …
Abstract
It is unknown whether closely related epidermal dendritic cells, Langerhans cells (LCs), and dermal dendritic cells (DDCs) have unique functions. In this study, we show that human DDCs have a broad TLR expression profile, whereas human LCs have a selective impaired expression of cell surface TLR2, TLR4, and TLR5, all involved in bacterial recognition. This distinct TLR expression profile is acquired during the TGF-β1-driven development of LCs in vitro. Consequently, and in contrast to DDCs, LCs weakly respond to bacterial TLR2, TLR4, and TLR5 ligands in terms of cytokine production and maturation, as well as to whole Gram-positive and Gram-negative bacteria, whereas their responsiveness to viral TLR ligands and viruses is fully active and comparable to DDCs. Unresponsiveness of LCs to bacteria may be a mechanism that contributes to tolerance to bacterial commensals that colonize the skin.
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