Antimicrobial efficacy of granulysin-derived synthetic peptides in acne vulgaris

BackgroundAntimicrobial peptides are considered as a potential alternative to antibiotic treatment in acne vulgaris because the development of a resistant strain of Propionibacterium acnes is problematic. Granulysin can be regarded as an ideal substance with which to treat acne because it has antimicrobial and anti-inflammatory effects. ObjectivesThis study was performed to explore the effectiveness of granulysin-derived peptides (GDPs) in killing P.acnes in vitro under a standard microbiologic assay and to evaluate their potential use in a topical agent for the treatment of acne vulgaris. MethodsTwenty different peptides based on the known sequence of a GDP were synthesized and tested in vitro for antimicrobial activity. Thirty patients with facial acne vulgaris were instructed to apply a topical formulation containing synthetic GDP to acne lesions twice per day for 12weeks. ResultsA newly synthesized peptide in which aspartic acid was substituted with arginine, and methionine was substituted with cysteine, showed the highest antimicrobial activity against P.acnes. Moreover, it was effective against both Gram-positive and Gram-negative bacteria in vitro. After treatment with the topical formulation containing 50ppm of synthetic peptide for 12weeks, a significant reduction in the number of pustules was observed, regardless of the increase in the number of comedones. In addition, a significant reduction in the clinical grade of acne based on the Korean Acne Grading System (KAGS) was evident. ConclusionsSynthesized GDP shows strong antimicrobial activity against P.acnes in vitro. The clinical improvement observed suggests a topical formulation containing the GDP has therapeutic potential for the improvement of inflammatory-type acne vulgaris by its antimicrobial activity.