Upregulation of TLR2 expression on G-CSF-mobilized peripheral blood stem cells is responsible for their rapid engraftment after allogeneic hematopoietic stem cell transplantation

Staphylococcus aureus recognition by hematopoietic stem and progenitor cells via TLR2/MyD88/PGE2 stimulates granulopoiesis in wounds

“…29 It is interesting to note that TLR2 signaling enhances myeloid differentiation of blood-derived HSCs far greater than BM-derived HSCs. 28 Thus, HSPCs mobilized in response to wounding-induced inflammatory mediators appear primed to respond to TLR2 stimulation and undergo granulopoiesis in the wound.…”

“…Indeed, WT HSPCs exhibited a trend for less efficient granulopoiesis in MyD88-deficient wounds, perhaps because of other upstream receptors including TLRs and/or IL-1R family members. In addition, HSCs upregulate TLR2 in response to G-CSF 28 and cutaneous S aureus infection induces gd T-cell production of IL-17, 27 which in turn induces G-CSF production in epithelial cells. 29 It is interesting to note that TLR2 signaling enhances myeloid differentiation of blood-derived HSCs far greater than BM-derived HSCs.…”

G-CSF-induced myeloid cells stimulated by TLR2 enhance engraftment after allogeneic hematopoietic stem cell transplantation

“…We previously showed that TLR2 is highly expressed on HSCs from G-CSF-treated mice. The HSCs are rapidly differentiated into myeloid cell types by endogenous ligand generated in allogeneic recipients [14]. Cumulatively, these results suggest thatTLR2 could be a functional molecule that mediates the biological effect of G-CSF.…”

“…Our previous results showed that G-CSF-mobilized PBSCs express high levels of TLR2 and that TLR2 signaling promoted the myeloid differentiation of PBSCs. This differentiation resulted in rapid cell engraftment [14]. Moreover, G-CSF is known to enhance TLR2 expression on certain types of immune cells [15][16][17].…”

Danger Signals and Graft-versus-host Disease: Current Understanding and Future Perspectives

“…TLR2 recognizes cell-wall components such as peptidoglycan (PGN) from gram-positive bacteria as well as zymosan from yeast. Intriguingly, granulocyte-colony stimulating factor (G-CSF) mobilized donor grafts showed the increase level of TLR2 expression on myeloid cell populations (19), but upregulated TLR2 expression did not correlate with enhanced allogeneic responses (20). The studies utilizing TLR2 −/− animals as either donor or host demonstrated that TLR2 has little effect on acute GVHD (12, 20).…”