IL-6 Generated from Human Hematopoietic Stem and Progenitor Cells through TLR4 Signaling Promotes Emergency Granulopoiesis by Regulating Transcription Factor Expression

Abstract Emergency granulopoiesis, also known as demand-adapted is defined the response of an organism to systemic bacterial infections, and it results in neutrophil mobilization from reservoir pools increased myelopoiesis bone marrow. Indirect direct initiating mechanisms emergency granulopoiesis have been hypothesized. However, detailed mechanism hyperactive marrow, which leads granulocyte left shift, remains unknown. In this study, we report that TLR4 expressed on granulo-monocytic progenitors, well mobilized human peripheral blood CD34+ cells, account for 0.2% monocytes blood, ∼ 10% LPS, a component Gram-negative bacteria infection, induces differentiation cells into myelocytes vitro via signaling pathway. Moreover, directly responded LPS stimulation by activating MAPK NF-κB pathways, they produced IL-6 promotes phosphorylating C/EBPα C/EBPβ, effect was suppressed action receptor inhibitor. This work supports finding TLR hematopoietic stem progenitor provides evidence can sense pathogens produce cytokines exerting autocrine and/or paracrine effects, thereby promoting differentiation.