Inhibitory effect of the antimicrobial peptide BLP-7 against Propionibacterium acnes and its anti-inflammatory effect on acne vulgaris.

Propionibacterium acnes (P. acnes) is a Gram-positive commensal bacterium, which is involved in the pathogenesis and inflammation of acne vulgaris. An antimicrobial peptide named bombinin-like peptide 7 (BLP-7), which was determined from Bombina orientalis , has been shown to possess certain antibacterial activity. This study was carried out with synthesized BLP-7 on the basis of the antimicrobial and anti-inflammatory activities against P. acnes in vitro and in vivo. The minimal inhibitory concentration (MIC) of BLP-7 against P. acnes is 5 μM. And BLP-7 exhibits strong resistance to heat, pH and salt concentration, but no significant cytotoxicity to normal human epidermal keratinocytes (NHEKs). Using the co-culture of P. acnes and NHEKs, this study demonstrated that BLP-7 significantly reduced the production of interleukin (IL)-8 and granulocyte-macrophage colony stimulating factor (GM-CSF), as well as the expression of these two pro-inflammatory cytokines at the transcriptional level. In a separate study, using the rat ear edema model, BLP-7 significantly suppressed P. acnes -induced skin inflammation, reducing the ear thickness by 54.21% of the negative control group. These results suggest that due to its anti- P. acnes and anti-inflammatory activities, BLP-7 could be used as a potential anti-acne agent. • The minimal inhibitory concentration of bombinin-like peptide 7 against Propionibacterium acnes is 5 μM. • Bombinin-like peptide 7 exhibits strong resistance to heat, pH and salt concentration. • Bombinin-like peptide 7 significantly reduced the production of two proinflammatory cytokines. • Bombinin-like peptide 7 significantly suppressed Propionibacterium acnes -induced skin inflammation. [ABSTRACT FROM AUTHOR]