Microfluidic investigation reveals distinct roles for actin cytoskeleton and myosin II activity in capillary leukocyte trafficking.
Circulating leukocyte sequestration in pulmonary capillaries is arguably the initiating event of lung injury in acute respiratory distress syndrome. We present a microfluidic investigation of the roles of actin organization and myosin II activity during the different stages of leukocyte trafficking through narrow capillaries (entry, transit and shape relaxation) using specific drugs (latrunculin A, jasplakinolide, and blebbistatin). The deformation rate during entry reveals that cell stiffness depends strongly on F-actin organization and hardly on myosin II activity, supporting a microfilament role in leukocyte sequestration. In the transit stage, cell friction is influenced by stiffness, demonstrating that the actin network is not completely broken after a forced entry into a capillary. Conversely, membrane unfolding was independent of leukocyte stiffness. The surface area of sequestered leukocytes increased by up to 160% in the absence of myosin II activity, showing the major role of molecular motors in microvilli wrinkling and zipping. Finally, cell shape relaxation was largely independent of both actin organization and myosin II activity, whereas a deformed state was required for normal trafficking through capillary segments.
Gabriele
Sylvain
S
Université de la Méditerranée, Institut National de la Santé et de la Recherche Médicale INSERM U600-Centre National de la Recherche Scientifique CNRS UMR6212, Marseille, France.
Benoliel
Anne-Marie
AM
Bongrand
Pierre
P
Théodoly
Olivier
O
D000199:Actins / Q000378:metabolism*; D000205:Actomyosin / Q000378:metabolism; D002196:Capillaries / Q000166:cytology*; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D002465:Cell Movement; D048430:Cell Shape; D003599:Cytoskeleton / Q000378:metabolism*; D006801:Humans; D007700:Kinetics; D007962:Leukocytes / Q000166:cytology*; D044085:Microfluidics; D024462:Myosin Type II / Q000378:metabolism*
D000199:Actins; D000205:Actomyosin; D024462:Myosin Type II