FIG 2.
Intracellular MRSA-induced cytokine expression and cytotoxicity in HaCaT keratinocytes. Keratinocytes were infected, treated with gentamicin to kill the extracellular S. aureus, and then treated with purified CPPTat-JDlys, JDlys proteins, or vancomycin. Infected cells were treated with PBS as a control. (A) The mRNA levels of TNF-α and IL-6 were measured by real-time PCR at 3 h after the treatments mentioned above. The levels of TNF-α and IL-6 mRNA were normalized to the levels of β-actin mRNA and then were expressed as the n-fold increases with respect to the levels in uninfected cells. (B) Effect of bacterial cell-mediated cytotoxicity measured by LDH cytotoxicity assays. Infected cells were treated with PBS as a control. Uninfected cells were treated with CPPTat-JDlys as a CPPTat-JDlys control. *, the cytokine levels or cytotoxicity for samples treated with CPPTat-JDlys were significantly lower (P < 0.05) than those for samples treated with JDlys, vancomycin, and the PBS control. The data shown are means ± SEMs from at least three independent experiments.