Procoagulant and proinflammatory effects of red blood cells on lipopolysaccharide-stimulated monocytes

J Thromb Haemost. 2015 Sep;13(9):1676-82. doi: 10.1111/jth.13041. Epub 2015 Jul 27.

Abstract

Background: We aimed to evaluate the mechanisms underlying the effects of red blood cells (RBCs) on the reactivity of monocytes to lipopolysaccharide (LPS) stimulation.

Methods: Measurements of tissue factor (TF) antigen and activity were performed on freshly isolated white blood cells (WBCs)/platelets resuspended in heparinized plasma, as well as cultured monocytic cells.

Results: In a dose-dependent manner, RBCs significantly enhanced LPS-induced TF activity and antigen levels in blood monocytes; potentiation of TF activity by both human and murine RBCs did not require the presence of neutrophils and/or platelets. We also measured the levels of monocyte chemotactic protein-1 (MCP-1), the key proinflammatory chemokine that binds to duffy antigen receptor for chemokines (DARC) on RBC surface, in plasma and RBC lysates after the incubation of RBCs with WBC/platelets; at the concentrations corresponding to normal blood counts, RBCs exerted a significant influence on the free plasma levels of MCP-1, with about two-thirds of detectable MCP-1 post-LPS stimulation being associated with RBCs. Critically, DARC-deficient murine RBCs failed to enhance LPS-induced TF activity, confirming the mechanistic significance of RBC-DARC.

Conclusions: Our study reports a novel mechanism by which RBCs promote procoagulant and proinflammatory sequelae of WBC exposure to LPS, likely mediated by RBC-DARC in the microenvironment(s) that bring monocytes and RBCs in close proximity.

Keywords: blood coagulation; chemokines; erythrocytes; lipopolysaccharides; thromboplastin.

MeSH terms

  • Adult
  • Animals
  • Blood Coagulation / physiology*
  • Cell Line
  • Chemokine CCL2 / biosynthesis*
  • Chemokine CCL2 / blood
  • Chemokine CCL2 / genetics
  • Duffy Blood-Group System / blood
  • Duffy Blood-Group System / immunology*
  • Endotoxemia / blood
  • Endotoxemia / immunology
  • Erythrocytes / immunology*
  • Gene Expression Regulation
  • Humans
  • Inflammation / blood*
  • Lipopolysaccharides / pharmacology
  • Lipopolysaccharides / toxicity
  • Mice
  • Mice, Inbred C57BL
  • Monocytes / drug effects
  • Monocytes / immunology*
  • Monocytes / metabolism
  • RNA, Messenger / biosynthesis
  • RNA, Messenger / blood
  • Receptors, Cell Surface / blood
  • Receptors, Cell Surface / deficiency
  • Receptors, Cell Surface / immunology*
  • Thromboplastin / biosynthesis*
  • Thromboplastin / genetics

Substances

  • ACKR1 protein, human
  • CCL2 protein, human
  • Chemokine CCL2
  • Dfy protein, mouse
  • Duffy Blood-Group System
  • Lipopolysaccharides
  • RNA, Messenger
  • Receptors, Cell Surface
  • lipopolysaccharide, E. coli O26-B6
  • lipopolysaccharide, Escherichia coli O111 B4
  • Thromboplastin