LPS Sensing Mounts an Adaptive MSC Response Enhancing Neutrophil Activation and Wound Healing

We here addressed the question whether the unique capacity of mesenchymal stromal/stem cells (MSCs) to re-establish tissue homeostasis depends on their potential to sense pathogen associated molecular pattern (PAMP) and, in consequence, mount an adaptive response in the interest of tissue repair. After injection of MSCs which had been primed with the bacterial wall component LPS into murine wounds, an unexpected acceleration of healing occurred, clearly exceeding that of non-primed MSCs. This correlates with a fundamental reprogramming of the transcriptome in LPS treated MSCs as deduced from RNA-seq analysis and its validation. A network of genes mediating the adaptive response through the TLR-4 pathway responsible for neutrophil activation (GCP- 2, ENA-78, IL-1ß IL-8) and MSC protection (SOX6) profoundly contributes to enhanced wound healing. In fact, silencing of either TRL-4, or IRAK3, a downstream effector of TRL-4, or SOX6 suppressed wound healing most likely due to suppression of neutrophil extracellular trap formation and suppression of the enhanced microbicidal release of reactive oxygen species (ROS), key features of neutrophil activation. This previously unreported results uncover SOX6 which protects MSCs at the wound site from enhanced oxidative stress. This unprecedented findings hold substantial promise to refine current MSC-based therapies for difficult-to-treat wounds. Overall design: Transcriptome profiling of MSCs

3

Munir S, Basu A, Maity P, Krug L, Haas P, Jiang D, Strauss G, Wlaschek M, Geiger H, Singh K, Scharffetter-Kochanek K