Impaired adhesion of neutrophils expressing Slc44a2/HNA-3b to VWF protects against NETosis under venous shear rates

• Published in: Blood 2021-04, Vol.137 (16), p.2256-2266
• Main Authors: Zirka, Gaïa, Robert, Philippe, Tilburg, Julia, Tishkova, Victoria, Maracle, Chrissta X., Legendre, Paulette, van Vlijmen, Bart J.M., Alessi, Marie-Christine, Lenting, Peter J., Morange, Pierre-Emmanuel, Thomas, Grace M.
• Format: Article
• Language: English
• Subjects: Animals; Blood Circulation; Cardiology and cardiovascular system; Cell Adhesion; Cell Behavior; Cells, Cultured; Cellular Biology; Extracellular Traps - genetics; Extracellular Traps - metabolism; Gene Expression; HEK293 Cells; Hematology; Human health and pathology; Humans; Isoantigens - genetics; Isoantigens - metabolism; Life Sciences; Male; Membrane Glycoproteins - genetics; Membrane Glycoproteins - metabolism; Membrane Transport Proteins - genetics; Membrane Transport Proteins - metabolism; Mice; Mice, Inbred C57BL; Neutrophils - cytology; Neutrophils - metabolism; Venous Thrombosis - genetics; Venous Thrombosis - metabolism; von Willebrand Factor - metabolism
• ISSN: 0006-4971; 1528-0020
• DOI: 10.1182/blood.2020008345

Genome-wide association studies linked expression of the human neutrophil antigen 3b (HNA-3b) epitope on the Slc44a2 protein with a 30% decreased risk of venous thrombosis (VT) in humans. Slc44a2 is a ubiquitous transmembrane protein identified as a receptor for von Willebrand factor (VWF). To explain the link between Slc44a2 and VT, we wanted to determine how Slc44a2 expressing either HNA-3a or HNA-3b on neutrophils could modulate their adhesion and activation on VWF under flow. Transfected HEK293T cells or neutrophils homozygous for the HNA-3a– or HNA-3b–coding allele were purified from healthy donors and perfused in flow chambers coated with VWF at venous shear rates (100 s−1). HNA-3a expression was required for Slc44a2-mediated neutrophil adhesion to VWF at 100 s−1. This adhesion could occur independently of β2 integrin and was enhanced when neutrophils were preactivated with lipopolysaccharide. Moreover, specific shear conditions with high neutrophil concentration could act as a “second hit,” inducing the formation of neutrophil extracellular traps. Neutrophil mobilization was also measured by intravital microscopy in venules from SLC44A2-knockout and wild-type mice after histamine-induced endothelial degranulation. Mice lacking Slc44a2 showed a massive reduction in neutrophil recruitment in inflamed mesenteric venules. Our results show that Slc44a2/HNA-3a is important for the adhesion and activation of neutrophils in veins under inflammation and when submitted to specific shears. The fact that neutrophils expressing Slc44a2/HNA-3b have a different response on VWF in the conditions tested could thus explain the association between HNA-3b and a reduced risk for VT in humans. •Slc44a2 expressed by neutrophils is important for their adhesion to VWF-A1 domain and can mediate NETosis on VWF at venous shear.•Slc44a2 importance in neutrophil recruitment on VWF is exacerbated during inflammation both in vitro and in vivo. [Display omitted]