RESUMEN
BACKGROUND: Propionibacterium acnes is a major contributing factor to the inflammatory component of acne. The interaction of P. acnes with keratinocytes leads to an innate immune response via activation of toll-like receptors (TLR2, TLR4) resulting in the production and secretion of pro-inflammatory mediators. SIG1273, an isoprenylcysteine small molecule modulates inflammatory signaling pathways and kills P. acnes. SIG1273 represents a novel cosmetic functional ingredient that provides relief from blemishes in acne prone skin. OBJECTIVE: To assess the keratinocyte response and microbial growth of SIG1273 in vitro and evaluate the tolerability of SIG1273 gel applied topically in acne prone subjects. METHODS: For in vitro studies, human keratinocytes were exposed in culture to live P. acnes and peptidoglycan (PGN) to induce IL-8 production. P. acnes were cultured to determine minimal inhibitory concentration and minimal bactericidal concentration values. A total of 30 subjects were randomized in a double-blind controlled trial receiving 3% SIG1273 gel or vehicle for 6 weeks. Evaluation included inflammatory lesions, noninflammatory lesions, microcomedones, Sebutape scores, and P. acnes counts. RESULTS: In vitro studies demonstrate SIG1273 inhibits P. acnes-induced IL-8 production and inhibits P. acnes growth. SIG1273 gel was well tolerated with no signs of stinging, redness, or itching. Furthermore, improvement in some aspects of acne was observed in subjects applying SIG1273 gel, including inflammatory lesions, microcomedone counts and Sebutape scores. Facial scrubs taken to measure P. acnes colony-forming units showed those applying SIG1273 gel had ~1.0 Log 10 colony reduction over the length of the study, a statistically significantly improvement when compared with vehicle. No significant effects above vehicle were observed for noninflammatory lesions. CONCLUSIONS: SIG1273 represents a novel cosmetic functional ingredient that provides a safe dual modulating benefit to individuals with acne prone skin by reducing P. acnes counts and reducing inflammation.