Figure 3.
Erythrocyte hemolysis, cytotoxtic properties of N-AgrD against epithelial cells and murine models of infection. (a) Heparinized human whole blood was processed and treated with N-ArgD peptides or saline control. N-AgrD F20 and N-AgrD F24 showed moderate hemolysis activity. The N-AgrD D20 peptide did not cause hemolysis. (b) A549 human alveolar epithelial cell and (c) HaCaT human keratinocyte cell lines were incubated with N-AgrD peptides for 120 min; cell damage was monitored by LDH release. All three peptides displayed significant cytolytic activity. Statistical analysis by one-way ANOVA; ***P <0.001. (d) Fluorescent microscopy of A549 cells after live/dead cell staining. (e) In vivo contribution of the N-AgrD F20 and N-AgrD F24 peptides as assessed in murine lesion infection models. Subcutaneous infection of C57Bl/6 mice with an S. aureus agr null strain was tested +/− addition of a 1:1 mixture of AgrD F20 and AgrD F24 (10 μg/ml) on contralateral flanks. Statistical analysis was performed by Student's t-test; **P <0.01. (f) Appearance of a representative infected mouse flank shows addition of the N-AgrD F20 + N-AgrD F24 peptides to the S. aureus agr null strain results in an approximate doubling of lesion area. All statistical data was expressed as mean ± standard deviation.