Figure 3

SAK-mediated plasmin activity increased infectious skin lesion size and bacterial load. A. Macroscopically apparent lesion size 10 days after subcutaneous inoculation with S. aureus Xen36. Mean and SD for skin lesions in WT/null mice (n = 12), α₂AP KO/null mice (n = 11), WT/huPlg mice (n = 17) and α₂AP KO/huPlg mice (n = 14), respectively. B. Lesion size: S. aureus Xen36 possesses a stable copy of the modified Photorhabdus luminescens luxABCDE operon. Evolution of bacterial spread was assessed non-invasively by bioluminescence image analysis of the surface area with signal > threshold. Mean and SEM for lesion size in the 4 groups. Dimensions for α₂AP KO/huPlg mice and WT/huPlg mice are compared to WT/null mice. C. Examples of bioluminescence photographs of the left flank lesion for representative animals of the 4 groups at day 9. D. Bacterial load: signal intensity of the infectious lesion site, in photons/s through a defined region of interest, which was used for all lesions. Bacterial density analysis shows that bacterial clearance is hampered by enhanced proteolytic activity. Mean and SEM for signal intensity in the 4 groups. Bacterial loads for α₂AP KO/huPlg, α₂AP KO/null and WT/huPlg mice are compared to WT/null mice. *denotes P < 0.05, **P < 0.01, ***P < 0.001.