Internalization and coreceptor expression are critical for TLR2-mediated recognition of lipoteichoic acid in human peripheral blood

Bunk, Sebastian, Sigel, Stefanie, Metzdorf, Daniela, Sharif, Omar, Triantafilou, Kathy ORCID: https://orcid.org/0000-0002-7473-6278, Triantafilou, Martha ORCID: https://orcid.org/0000-0002-8489-2602, Hartung, Thomas, Knapp, Sylvia and von Aulock, Sonja 2010. Internalization and coreceptor expression are critical for TLR2-mediated recognition of lipoteichoic acid in human peripheral blood. The Journal of Immunology 185 (6) , pp. 3708-3717. 10.4049/jimmunol.0901660

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Abstract

Lipoteichoic acid (LTA), a ubiquitous cell wall component of Gram-positive bacteria, represents a potent immunostimulatory molecule. Because LTA of a mutant Staphylococcus aureus strain lacking lipoproteins (Δlgt-LTA) has been described to be immunobiologically inactive despite a lack of ascertained structural differences to wild-type LTA (wt-LTA), we investigated the functional requirements for the recognition of Δlgt-LTA by human peripheral blood cells. In this study, we demonstrate that Δlgt-LTA–induced immune activation critically depends on the immobilization of LTA and the presence of human serum components, which, to a lesser degree, was also observed for wt-LTA. Under experimental conditions allowing LTA-mediated stimulation, we found no differences between the immunostimulatory capacity of Δlgt-LTA and wt-LTA in human blood cells, arguing for a limited contribution of possible lipoprotein contaminants to wt-LTA–mediated immune activation. In contrast to human blood cells, TLR2-transfected human embryonic kidney 293 cells could be activated only by wt-LTA, whereas activation of these cells by Δlgt-LTA required the additional expression of TLR6 and CD14, suggesting that activation of human embryonic kidney 293 cells expressing solely TLR2 is probably mediated by residual lipoproteins in wt-LTA. Notably, in human peripheral blood, LTA-specific IgG Abs are essential for Δlgt-LTA–mediated immune activation and appear to induce the phagocytic uptake of Δlgt-LTA via engagement of FcγRII. In this study, we have elucidated a novel mechanism of LTA-induced cytokine induction in human peripheral blood cells that involves uptake of LTA and subsequent intracellular recognition driven by TLR2, TLR6, and CD14.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Medicine
Subjects:	R Medicine > RZ Other systems of medicine
Publisher:	American Association of Immunologists
ISSN:	0022-1767
Last Modified:	19 Oct 2022 10:35
URI:	https://orca.cardiff.ac.uk/id/eprint/24887

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