Staphylococcus aureus–derived lipoteichoic acid induces temporary T-cell paralysis independent of Toll-like receptor 2

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The interplay between microbes and surface organs, such as the skin, shapes a complex immune system with several checks and balances. The first-line defense is mediated by innate immune pathways leading to inflammation. In the second phase specific Tcells invade the infected organ, amplifying inflammation and defense. Consecutively, termination of inflammation is crucial to avoid chronic inflammation triggered by microbes, such as in patients with atopic dermatitis. We aimed to elucidate how the Staphylococcus aureus-derived cell-wall component lipoteichoic acid (LTA) governs the second phase of immune responses when high concentrations of LTA access Tcells directly through disrupted skin. We analyzed the direct exposure of Tcells to LTA invitro. For invivo analyses, we used fluorescein isothiocyanate contact hypersensitivity and ovalbumin-induced dermatitis as models for TH2-mediated cutaneous inflammation. We observed that LTA potently suppressed T-lymphocyte activation in a Toll-like receptor 2-independent manner. LTA-exposed Tcells did not proliferate and did not produce cytokines. Importantly, these Tcells remained completely viable and were responsive to consecutive activation signals on subsequent removal of LTA. Thus LTA exposure resulted in temporary functional T-cell paralysis. Invivo experiments revealed that T-cell cytokine production and cutaneous recall responses were significantly suppressed by LTA. We identified a new mechanism through which bacterial compounds directly but temporarily modulate adaptive immune responses.