The impact ofStaphylococcus aureuscell wall glycosylation on langerin recognition and Langerhans cell activation

Staphylococcus aureusis the leading cause of skin and soft tissue infections. It remains incompletely understood how skin-resident immune cells respond toS. aureusinvasion and contribute to an effective immune response. Langerhans cells (LCs), the only professional antigen-presenting cell type in the epidermis, senseS. aureusthrough their pattern-recognition receptor langerin, triggering a pro-inflammatory response. Langerin specifically recognizes the β-1,4-linkedN-acetylglucosamine (β-GlcNAc) modification, which requires the glycosyltransferase TarS, on the cell wall glycopolymer Wall Teichoic Acid (WTA). Recently, an alternative WTA glycosyltransferase, TarP, was identified in methicillin-resistantS. aureusstrains belonging to clonal complexes (CC) 5 and CC398. TarP also modifies WTA with β-GlcNAc but at the C-3 position of the WTA ribitol phosphate (RboP) subunit. Here, we aimed to unravel the impact of β-GlcNAc linkage position for langerin binding and LC activation. In addition, we performed structure-binding studies using a small panel of unique chemically-synthesized WTA molecules to assess langerin-WTA binding requirements. Using FITC-labeled recombinant human langerin and genetically-modifiedS. aureusstrains, we observed that langerin similarly recognized bacteria that produce either TarS- or TarP-modified WTA. Furthermore, using chemically-synthesized WTA, representative of the differentS. aureusWTA glycosylation patterns, established that β-GlcNAc is sufficient to confer langerin binding. Functionally,tarP-expressingS. aureusinduce increased cytokine production and maturation ofin vitro-generated LCs compared totarSexpressingS. aureus. Overall, our data suggest that LCs are able to sense all β-GlcNAc-WTA producingS. aureusstrains, likely performing an important role as first responders uponS. aureusskin invasion.