Neutrophils exhibit distinct migration phenotypes that are modulated by transendothelial migration

The extravasation of polymorphonuclear neutrophils (PMNs) is a critical component of the innate immune response that involves transendothelial migration (TEM) and interstitial migration. TEM-mediated interactions between PMNs and vascular endothelial cells (VECs) trigger a cascade of biochemical and mechanobiological signals whose effects on interstitial migration are currently unclear. To address this question, we cultured human VECs on a fibronectin-treated transwell insert to model the endothelium and basement membrane, loaded differentiated HL60 (dHL-60) neutrophils in the upper chamber of the insert, and collected neutrophils that crossed the membrane-supported monolayer from the lower chamber. The 3D chemotactic migration of the TEM-conditioned dHL-60 neutrophils through collagen matrices was then quantified. Data collected from over 60,000 trajectories showed two distinct migratory phenotypes, i.e., a high-persistence phenotype and a low-persistence phenotype. These phenotypes were conserved across treatment conditions, and their existence was confirmed in human primary PMNs. The high-persistence phenotype was characterized by more straight trajectories and faster migration speeds, whereas the low-persistence one exhibited more frequent sharp turns and loitering periods. A key finding of our study is that TEM increased low-persistence migration prevalence. Changes in the relative proportion of high-persistence and low-persistence populations correlated with G protein-coupled receptor kinase 2 (GRK2) expression levels. Inhibiting GRK2 hindered the TEM-induced shift in migratory phenotype and impaired the phagocytic function of dHL-60 neutrophils. Consistent with this finding, primary human PMNs displayed comparable TEM-driven GRK2 upregulation and shifts in migratory behavior better suited for spatial exploration, demonstrating that this regulatory axis operates in native neutrophils. These observations provide novel insight into the biophysical impacts of TEM, suggesting that priming PMNs is essential to conduct sentinel functions.