Sickle cell vaso-occlusion: multistep and multicellular paradigm.

Area of Science:

• Hematology
• Vascular Biology
• Immunology

Background:

• Sickle cell disease (SCD) causes painful episodes and organ damage via microvascular occlusion.
• Previous studies identified increased sickle erythrocyte adherence to endothelial cells, but in vivo relevance was unclear.
• Clinical data link leukocytosis to SCD severity and suggest leukocytes precipitate crises.

Purpose of the Study:

• To evaluate the in vivo relevance of cellular interactions in sickle cell vaso-occlusion.
• To propose a novel multistep model for vaso-occlusion involving leukocytes.
• To identify potential therapeutic targets in sickle cell disease.

Main Methods:

• Utilized intravital microscopy to observe interactions in inflamed venules.
• Proposed a multistep model integrating endothelial activation, leukocyte recruitment, and erythrocyte-leukocyte interactions.
• Reviewed clinical data and experimental findings.

Main Results:

• Sickle erythrocytes interact with adherent leukocytes in inflamed microvasculature.
• A novel model posits endothelial activation leads to leukocyte recruitment, which then interacts with sickle erythrocytes.
• This erythrocyte-leukocyte interaction impedes blood flow, leading to vaso-occlusion.

Conclusions:

• Adherent leukocytes critically participate in sickle cell vaso-occlusion.
• The proposed model highlights erythrocyte-leukocyte interactions as a key mechanism in SCD.
• This understanding opens new avenues for therapeutic interventions targeting leukocyte involvement.