A key step in neutrophil-mediated tissue damage is the migration of activated neutrophils across the vascular endothelium. Previously, we identified
protein kinase C δ as a critical regulator of neutrophil migration in
sepsis but did not identify specific steps in migration. In this study, we used our novel biomimetic microfluidic assay to delineate systematically the mechanism by which
protein kinase C δ regulates individual steps in human neutrophil-endothelial interaction during
inflammation. The biomimetic microfluidic assay includes a network of vascular channels, produced from in vivo images connected to a tissue compartment through a porous barrier. HUVECs cultured in vascular channels formed a complete lumen under physiologic shear flow. HUVECs were pretreated with TNF-α ± a
protein kinase C δ inhibitor, and the tissue compartment was filled with a
chemoattractant (fMLP or IL-8). Under physiologic shear flow, the role of
protein kinase C δ on spatial and temporal neutrophil adherence/migration was quantified.
Protein kinase C δ inhibition significantly reduced neutrophil adhesion in response to fMLP and
IL-8 only under low shear rate and near bifurcations.
Protein kinase C δ inhibition also decreased adherence to nonactivated HUVECs in response to fMLP or
IL-8.
Protein kinase C δ inhibition reduced neutrophil migration into the tissue compartment in response to fMLP and to a lesser degree, to
IL-8. Antibody-coated microparticles demonstrated that
protein kinase C δ inhibition down-regulated
E-selectin and
ICAM-1 but not
VCAM-1 expression. With the use of a physiologically relevant in vitro model system, we demonstrate that
protein kinase C δ plays an important role in the regulation of neutrophil adherence/migration during
inflammation and identifies key steps regulated by
protein kinase C δ in neutrophil-endothelial interactions.