Lugdunin amplifies innate immune responses in the skin in synergy with host- and microbiota-derived factors

Recently our groups discovered lugdunin, a new cyclic peptide antibiotic that inhibits Staphylococcus aureus epithelial colonization in humans and rodents. In this work, we analyzed its immuno-modulatory and antimicrobial potential as a single agent or in combination with other microbiota- or host-derived factors. We show that pretreatment of primary human keratinocytes or mouse skin with lugdunin in combination with microbiota-derived factors results in a significant reduction of S. aureus colonization. Moreover, lugdunin increases expression and release of LL-37 and CXCL8/MIP-2 in human keratinocytes and mouse skin, and results in the recruitment of monocytes and neutrophils in vivo, both by a TLR/MyD88-dependent mechanism. Interestingly, S. aureus elimination by lugdunin is additionally achieved by synergistic antimicrobial activity with LL-37 and dermcidin-derived peptides. In summary, our results indicate that lugdunin provides multi-level protection against S. aureus and may thus become a promising treatment option for S. aureus skin infections in the future.

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Policy information about availability of computer code Data collection qPCR data were collected using a LightCycler96 (Roche). Flow cytometry data were acquired on a BD LSR II (BD Bioscience) with BD FACSDiva software.

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GraphPad Prism 7 (GraphPad Software, Inc.) was used to prepare graphs and to perform statistical analyses. Flow cytometry data were analyzed using FlowJo v10 (Treestar, Inc.). Combination indices (CI) were calculated using CompuSyn (ComboSyn, Inc.) and indicated in median effect plots as a function of the bacteria fractions affected by the combinatorial peptide treatment.
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April 2018
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To prepare single-cell suspensions, relevant dorsal skin area was transferred to PBS + 2% FBS (Biochrom/ Merck Millipore). Subcutaneous fat was removed using a razor blade and skin tissue was transferred into a 2 mL reaction tube containing digestion solution.

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