The integrin linked kinase is required for chemokine-triggered high affinity conformation of neutrophil β2-integrin LFA1.

Neutrophil adhesion and extravasation into tissue at sites of injury or infection depend on binding of integrin lymphocyte function-associated antigen-1 (LFA-1) to ICAM-1 expressed on activated endothelial cells. The activation-dependent conformational change of LFA-1 to the high affinity conformation (H+) requires kindlin-3 binding to the β2-integrin cytoplasmic domain. Here we show that genetic deletion of the known kindlin-interactor integrin linked kinase (ILK) impaired neutrophil adhesion and extravasation in the cremaster muscle and in a clinically relevant model of renal-ischemia-reperfusion injury. Utilizing in vitro microfluidic adhesion chambers and conformation specific antibodies, we show that knockdown of ILK in HL-60 cells reduces the conformational change of β2-integrins to the H+ conformation. Mechanistically, we found that ILK is required for PKC membrane targeting and for chemokine-induced upregulation of its kinase activity. Moreover, PKC-α deficiency also results in impaired leukocyte adhesion in bone marrow chimeric mice. Mass spectrometric and western blot analyses revealed a stimulation- and ILK-dependent phosphorylation of kindlin-3 upon activation. In sum our data indicate an important role of ILK in kindlin-3-dependent conformational activation of LFA-1.