Neutrophil F-actin and myosin but not microtubules functionally regulate transepithelial migration induced by interleukin 8 across a cultured intestinal epithelial monolayer.

The role of the polymorphonuclear leukocyte (PMN) cytoskeleton during the transmigration across colonic epithelial cells is not very well understood. In order to study the role of different components of the PMN cytoskeleton during transepithelial migration across a colonic epithelial cell monolayer (T84), PMN were preincubated with drugs affecting either the actin cytoskeleton (cytochalasin B, iota toxin of Clostridium perfringens, and phalloidin) or the microtubules (colchicine and taxol). The role of PMN myosin during transepithelial migration was investigated using the inhibitor 2,3-butanedione monoxime (BDM) and DC3B toxin. PMN intracellular Ca2+, during neutrophil adhesion and translocation across the epithelium, was assessed by the Ca2+ chelator 1, 2bis-(2-aminophenoxy)-ethane-N,N,N', N'-tetra-acetic acid tetrakis (acetoxymethyl) ester (BAPTA-AM). Transmigration of PMN was initiated by applying either interleukin-8 or formyl-met-leu-phe (fMLP). While colchicine and taxol preexposure did not influence PMN transepithelial migration, treatment with cytochalasin B, iota toxin, phalloidin, BDM, DC3B toxin and BAPTA-AM greatly diminished migration of PMN across T84 monolayers. Similarly, cell-cell contacts established between PMN and epithelial cells during the transmigration were diminished after treatment of PMN with iota toxin or cytochalasin B. These data show that the neutrophil actin cytokeleton and myosin, but not the microtubules, evoke a Ca2+ -dependent motility that facilitates migration across the colonic epithelial barrier.