Inhibitory and anti-inflammatory effects of the Helicobacter pylori-derived antimicrobial peptide HPA3NT3 against Propionibacterium acnes in the skin.

BACKGROUND An effective treatment strategy for acne vulgaris is the reduction of Propionibacterium acnes in the skin. The Helicobacter pylori-derived synthetic antimicrobial peptide HPA3NT3 is a customized α-helical cationic peptide with antibacterial and anti-inflammatory activity. OBJECTIVES To examine the role of HPA3NT3 as a treatment against P. acnes-induced skin inflammation. METHODS Morphological alteration of individual P. acnes cells by HPA3NT3 was visualized by scanning electron microscopy. Modulation by HPA3NT3 of a number of P. acnes-induced innate immune responses was analysed in vitro using cultured normal human keratinocytes (HKs), and in vivo using the ICR mouse, a well-established model for P. acnes-induced skin inflammation. RESULTS The minimum inhibitory concentration of HPA3NT3 against P. acnes was low (0·4 μmol L(-1)). HPA3NT3 showed no cytotoxicity to HK cells at the concentrations used in our in vitro and in vivo studies. Treatment with HPA3NT3 in vitro induced morphological disruptions in P. acnes cells suggestive of a bactericidal effect. HPA3NT3 significantly decreased P. acnes-induced interleukin-8 expression and intracellular calcium mobilization in HK cells by inhibiting P. acnes-activated Toll-like receptor 2-mediated nuclear factor-κB signalling pathways. Intradermal injection of HPA3NT3 in vivo effectively decreased viable P. acnes, as well as erythema, swelling and inflammatory-cell infiltration in ICR mouse ears inoculated with P. acnes. CONCLUSIONS Our data suggest that HPA3NT3 has potential as a therapeutic agent for acne vulgaris due to its antimicrobial effects on P. acnes and its ability to block P. acnes-induced inflammation.