Protective Role of Surfactant Protein D in Ocular Staphylococcus aureus Infection
Fig 5
SP-D promoted S. aureus phagocytosis by neutrophils in ocular surface, but cysteine protease impaired SP-D activity.
After inoculation with 107 CFUs of bacteria or bacteria with 10nM E64 for 6h, tear fluid was collected and the cells were mounted on slides by cytospin centrifugation method. The cells were stained and one hundred randomly selected neutrophils per slide were analyzed at x1,000 magnification. Neutrophils that phagocytized at least one bacterium were counted as bacteria-positive neutrophils. The phagocytic index (PI) was calculated as the percentage of bacteria-positive neutrophils multiplied by the average number of bacteria per bacteria-positive neutrophils. Panel A shows neutrophils with bacteria stained using the Hema-3 Stain Kit. Panel B shows PI in infected WT and SP-D KO mice. “#” marked neutrophils. Arrows point to S. aureus. Scale bars: 3 μm. The results shown are from three independent experiments (n = 8 to 12 mice per group). All values represent mean ± SE. * p<0.05 in student’s t test.