Interaction of kindlin-3 and b2-integrins differentially regulates neutrophil recruitment and NET release in mice

• Kindlin-3–b2-integrin signaling in neutrophils is involved in regulation of both neutrophil recruitment and NET release. • Disrupting the crosstalk between kindlin-3 and b2-integrins in neutrophils with a blocking peptide preferentially attenuates NET release. Kindlin-3 essentially supports integrin activation in blood cells. Absence of kindlin-3 in humanscauses leukocyte adhesiondeficiency-III characterizedwith severe bleedingdisorder and recurrent infections. Previously, we generated kindlin-3 knock-in (K3KI) mice carrying an integrin-interaction disrupting mutation in kindlin-3 and verified the functional significance of the binding of kindlin-3 to integrin aIIbb3 in platelets. Here, using K3KI mice, we functionally evaluate the crosstalk between kindlin-3 and b2-integrins in neutrophils. Although the kindlin-3mutant in K3KI neutrophils is normally expressed, its binding ability to b2-integrins in neutrophils is disabled. In vitro and in vivo analyses disclose that b2-integrin–mediated K3KI neutrophil adhesion and recruitment are significantly suppressed. Interestingly, the ability of releasing neutrophil extracellular traps (NETs) fromK3KI neutrophils is also compromised. Substantially, a peptide derived from the integrin b2 cytoplasmic tail that can inhibit the interaction between kindlin-3 and b2-inegrins significantly jeopardizes NET release without affecting neutrophil adhesion and recruitment under the experimental conditions. These findings suggest that crosstalk between kindlin-3 and b2-integrins in neutrophils is required for supporting both neutrophil recruitment andNET release, but the involved regulatorymechanisms in these two cellular eventsmight be differential, thus providing a novel therapeutic concept to treat innate immune-related diseases. (Blood. 2015;126(3):373-377)