Live imaging reveals distinct modes of neutrophil and macrophage migration within interstitial tissues

Abstract

Cell motility is required for diverse processes during immunity and inflammation. Classically, leukocyte motility is defined as an amoeboid type of migration, however some leukocytes, like macrophages, also employ a more mesenchymal mode. Here, we sought to characterize the mechanisms that regulate neutrophil and macrophage migration in vivo using dual real time imaging of leukocyte motility within interstitial tissues in zebrafish larvae. Neutrophils displayed a rounded morphology and rapid protease independent motility, lacked defined paxillin punctae and had persistent rearward polarization of stable F-actin and the microtubule network. By contrast, macrophages displayed an elongated morphology with reduced speed and increased directional persistence and formed paxillin-containing punctae but had less defined polarization of the microtubule and actin networks. We also observed differential effects of protease inhibition, microtubule disruption and ROCK inhibition on the efficiency of neutrophil and macrophage motility. Taken together, our findings suggest that larval zebrafish neutrophils and macrophage display distinct modes of migration within interstitial tissues in vivo.