Cunning Pathogen Tactics: Neutrophil Movement Influenced by Bacterial Attractants in the Experimental Model

Abstract

To explore the peculiarities of neutrophil motility, two models of chemoattraction were created: a horizontal model, where a container with bacterial chemoattractant was attached laterally to the endotheliocyte monolayer, and a vertical model, simulating a pyemic focus in the lower part of the modified Boyden chamber. Low-molecular weight product secretion and/or degradation of Enterococcus faecalis caused “disorientations” of neutrophil migration with hyperproduction reactive oxygen species (ROS) by immune cells, while Proteus mirabilis inhibited both migration of most neutrophils and the production of ROS by them, while the activity of the remaining uninhibited neutrophils increased. Neutrophils generated ROS during migration, especially actively in the case of a large number of mobile cells (under stimulation with low-molecular weight product secretion and/or degradation of Enterococcus faecalis and Escherichia coli). Using high-resolution microscopy, it was shown that low-activity neutrophils cause changes in the morphology of endothelial cells during migration more than high-activity neutrophils. In the vertical migration model, the morphology of endothelial cells significantly changed during neutrophils diapedesis. It was observed that space between endothelial cells was increased (especially in the case of neutrophil swarming).