Abstract

Neutrophils are essential to protect the host against invading pathogens but can promote disease progression in sickle cell disease (SCD) by becoming adherent to inflamed microvascular networks in peripheral tissue throughout the body. During the inflammatory response, leukocytes extravasate from the bloodstream using selectin adhesion molecules and migrate to sites of tissue insult through activation of integrins that are essential for combating pathogens. However, during vaso-occlusion associated with SCD, neutrophils are activated during tethering and rolling on selectins upregulated on activated endothelium that line blood vessels. Recently, we reported that recognition of sLex on L-selectin by E-selectin during neutrophil rolling initiates shear force resistant catch-bonds that facilitate tethering to endothelium and activation of integrin bond clusters that anchor cells to the vessel wall. Evidence indicates that blocking this important signaling cascade prevents the congestion and ischemia in microvasculature that occurs from neutrophil capture of sickled red blood cells, which are normally deformable ellipses that flow easily through small blood vessels. Two recently completed clinical trials of therapies targeting selectins and their effect on neutrophil activation in small blood vessels reveal the importance of mechanoregulation that in health is an immune adaption facilitating rapid and proportional leukocyte adhesion, while sustaining tissue perfusion. We provide a timely perspective on the mechanism underlying vaso-occlusive crisis (VOC) with a focus on new drugs that target selectin mediated integrin adhesive bond formation.

Highlights

  • Sickle cell disease (SCD) is an inherited disease characterized by defects in hemoglobin that distorts red blood cells (RBC) into a “sickle” shape [1,2,3]

  • E-selectin binding to Sialyl Lewisx (sLex) supports capture and rolling of human, but not murine neutrophils thereby providing a key event for subsequent mechanosignaling of integrin activation that mediates leukocyte arrest even in absence of chemokine signaling [29]

  • The importance of selectins in Vaso-occlusive crisis (VOC) was rigorously studied by Hidalgo et al, who first reported in a humanized sickle cell mouse model that E-selectin mediated activation of b2-integrins at the leading edge of a neutrophil promotes transition from rolling to arrest in an inflamed microvascular bed [39]

Read more

Summary

Introduction

Sickle cell disease (SCD) is an inherited disease characterized by defects in hemoglobin that distorts red blood cells (RBC) into a “sickle” shape [1,2,3]. E-selectin binding to sLex supports capture and rolling of human, but not murine neutrophils thereby providing a key event for subsequent mechanosignaling of integrin activation that mediates leukocyte arrest even in absence of chemokine signaling [29].

Results
Conclusion
Full Text
Published version (Free)

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call