Subject(s)
Benzylamines/pharmacology , Cyclams/pharmacology , Granulocyte Colony-Stimulating Factor/pharmacology , Hematopoietic Stem Cell Mobilization/methods , Hematopoietic Stem Cells/physiology , Nitric Oxide/metabolism , Receptor, PAR-1/metabolism , Thrombin/metabolism , Animals , Anti-HIV Agents/pharmacology , Apoptosis , Cell Proliferation , Cells, Cultured , Hematopoietic Stem Cells/cytology , Hematopoietic Stem Cells/drug effects , Mice , Receptor, PAR-1/genetics , Thrombin/geneticsABSTRACT
Neutrophils provide first line of host defense against bacterial infections utilizing glycolysis for their effector functions. How glycolysis and its major byproduct lactate are triggered in bone marrow (BM) neutrophils and their contribution to neutrophil mobilization in acute inflammation is not clear. Here we report that bacterial lipopolysaccharides (LPS) or Salmonella Typhimurium triggers lactate release by increasing glycolysis, NADPH-oxidase-mediated reactive oxygen species and HIF-1α levels in BM neutrophils. Increased release of BM lactate preferentially promotes neutrophil mobilization by reducing endothelial VE-Cadherin expression, increasing BM vascular permeability via endothelial lactate-receptor GPR81 signaling. GPR81-/- mice mobilize reduced levels of neutrophils in response to LPS, unless rescued by VE-Cadherin disrupting antibodies. Lactate administration also induces release of the BM neutrophil mobilizers G-CSF, CXCL1 and CXCL2, indicating that this metabolite drives neutrophil mobilization via multiple pathways. Our study reveals a metabolic crosstalk between lactate-producing neutrophils and BM endothelium, which controls neutrophil mobilization under bacterial infection.
Subject(s)
Bone Marrow Cells/immunology , Lactic Acid/metabolism , Neutrophils/immunology , Receptors, G-Protein-Coupled/metabolism , Salmonella Infections/immunology , Animals , Bone Marrow/blood supply , Bone Marrow Cells/metabolism , Disease Models, Animal , Endothelium, Vascular/metabolism , Female , Humans , Lipopolysaccharides/immunology , Male , Mice , Mice, Knockout , Neutrophils/metabolism , Receptors, G-Protein-Coupled/genetics , Salmonella Infections/microbiology , Salmonella typhimurium/immunology , Signal Transduction/immunologyABSTRACT
Hematopoietic stem and progenitor cells (HSPCs) tightly couple maintenance of the bone marrow (BM) reservoir, including undifferentiated long-term repopulating hematopoietic stem cells (LT-HSCs), with intensive daily production of mature leukocytes and blood replenishment. We found two daily peaks of BM HSPC activity that are initiated by onset of light and darkness providing this coupling. Both peaks follow transient elevation of BM norepinephrine and TNF secretion, which temporarily increase HSPC reactive oxygen species (ROS) levels. Light-induced norepinephrine and TNF secretion augments HSPC differentiation and increases vascular permeability to replenish the blood. In contrast, darkness-induced TNF increases melatonin secretion to drive renewal of HSPCs and LT-HSC potential through modulating surface CD150 and c-Kit expression, increasing COX-2/αSMA+ macrophages, diminishing vascular permeability, and reducing HSPC ROS levels. These findings reveal that light- and darkness-induced daily bursts of norepinephrine, TNF, and melatonin within the BM are essential for synchronized mature blood cell production and HSPC pool repopulation.
