Neutrophils exhibit distinct migration phenotypes that are modulated by transendothelial migration

Area of Science:

• Immunology
• Cell Biology
• Biophysics

Background:

• Polymorphonuclear neutrophils (PMNs) extravasation is vital for innate immunity, involving transendothelial migration (TEM) and interstitial movement.
• The impact of TEM on subsequent PMN interstitial migration remains poorly understood, despite TEM triggering complex signaling cascades.

Purpose of the Study:

• To investigate how transendothelial migration (TEM) influences the 3D migratory behavior of polymorphonuclear neutrophils (PMNs).
• To identify the molecular mechanisms, specifically the role of G protein-coupled receptor kinase 2 (GRK2), regulating PMN migration phenotypes post-TEM.

Main Methods:

• Human vascular endothelial cells (VECs) and differentiated HL60 (dHL-60) neutrophils were used to model the endothelium and basement membrane.
• TEM-conditioned dHL-60 neutrophils were analyzed for their 3D chemotactic migration through collagen matrices, quantifying migratory phenotypes.
• G protein-coupled receptor kinase 2 (GRK2) expression levels were assessed, and its inhibition was studied in relation to PMN migration and phagocytosis.

Main Results:

• Two distinct PMN migratory phenotypes were identified: high-persistence (straight, fast) and low-persistence (erratic, slow).
• Transendothelial migration (TEM) significantly increased the prevalence of the low-persistence phenotype.
• TEM-induced shifts in migratory phenotype correlated with GRK2 expression, and GRK2 inhibition counteracted these shifts and impaired phagocytosis.

Conclusions:

• Transendothelial migration (TEM) conditions PMNs to adopt a less persistent migratory phenotype, facilitating spatial exploration.
• G protein-coupled receptor kinase 2 (GRK2) is a key regulator of this TEM-induced migratory reprogramming in PMNs.
• This regulatory axis is conserved in primary human PMNs, highlighting its importance for innate immune sentinel functions.