Figure 1.

ExoU effect on blood cell–endothelium interaction. Leukocyte rolling on (A) and adhesion to (B) the endothelium was significantly higher in PA103-infected mice than in PA103ΔexoU-infected or in control animals. Data are means (and SEM) of the results obtained with six animals from each group, and are representative of the results obtained in two different experiments. *P < 0.05 and ***P < 0.001 when the values obtained from PA103ΔexoU-infected and control mice were compared with those obtained from animals infected with the ExoU-producing PA103 strain. In panels C–F microvessels from PA103-infected mice are shown. Note the presence of rhodamin-labeled cell aggregates of different sizes in the blood vessel lumina (arrows in panels C and D) or adherent to the endothelium (asterisk in panel E), forming a structure that narrowed the blood vessel lumen. In this figure, panel F exhibits the same vessels as shown in panel E, labeled with the FITC-dextran complex. Note the absence of perfusion in the area labeled with the asterisks. The inset included in panel D shows leukocyte rolling/adhesion to brain venule endothelium from PA103-infected mice. In panels G and H, microvessels from PA103ΔexoU-infected and control non-infected mice are shown, respectively. Note the absence of cell aggregates in the microvessel lumina. Final magnification, × 200; scale bar: 100 μm.