Two Distinct Coagulase-Dependent Barriers Protect Staphylococcus aureus from Neutrophils in a Three Dimensional in vitro Infection Model (original) (raw)
Figure 7
S. aureus Newman microcolonies are protected from neutrophils by MAM.
Neutrophils approached Newman wildtype microcolonies grown in 3D-CoG and immediately started phagocytosis (A, picture 3 h after challenge with neutrophils). The sae mutant (Newman-29) grown in 3D-CoG/Fib was attacked in the same way (B, picture 3 h after challenge with neutrophils). Wildtype microcolonies grown in 3D-CoG/Fib were not approached by neutrophils within 3 h (C, D). This can be depicted more clearly by time projection (0–3 h) of single frames from Video S3 (E). In contrast to this, the vWbp emp double mutant was readily approached by neutrophils which were only held back by the pseudocapsule (F–H, see Video S5). This neutrophil-free halo surrounding the microcolonies was measured and revealed a correlation with the MAM (I). Green: GFP-neutrophils; Blue: Sytox Blue-stained DNA; White: confocal reflection microscopy showing collagen fibers. Scale bar 50 µm. The microcolony in H is illustrated by a dotted line. The images are representative of at least three independent experiments. Data in I are averaged from three independent experiments.