TNF and infection: Because IL-8 and TNF-α are inflammatory mediators likely to participate in the response to cutaneous infections, we used real-time RT-PCR (Fig 2) and ELISA (Fig 3) to measure the effects of P5 (0.8 or 1.6 μM) on the expression of IL-8 and TNF-α 24 h after pre-infection (1x108 CFU/ml) of HKs with P. acnes. We found that relative levels of both IL-8 and TNF-α mRNA (Fig 2A and 2B, respectively) and protein (Fig 3A and 3B respectively) were significantly upregulated after P. acnes infection, and those responses were significantly inhibited by P5.