Licochalcone A attenuates acne symptoms mediated by suppression of NLRP3 inflammasome

Activation of the NACHT, LRR and PYD domains-containing protein 3 (NLRP3) inflammasome by Propionibacterium acnes (P. acnes) is critical for inducing inflammation and aggravating the development of acne lesions. We searched for available small-molecule inhibitors of the NLRP3 inflammasome that could be topically administered for the treatment of acne. We found that licochalcone A, a chalconoid isolated from the root of Glycyrrhiza inflate, was an effective inhibitor for P. acnes-induced NLRP3 inflammasome activation. Licochalcone A blocked P. acnes-induced production of caspase-1(p10) and IL-1β in primary mouse macrophages and human SZ95 sebocytes, indicating the suppression of NLRP3 inflammasome. Licochalcone A suppressed P. acnes-induced ASC speck formation and mitochondrial reactive oxygen species. Topical application of licochalcone A to mouse ear skin attenuated P. acnes-induced skin inflammation as shown by histological assessment, ear thickness measurement, and inflammatory gene expression. Licochalcone A reduced caspase-1 activity and IL-1β production in mouse ear injected with P. acnes. This study demonstrated that licochalcone A is effective in the control of P. acnes-induced skin inflammation as an efficient inhibitor for NLRP3 inflammasome. Our study provides a new paradigm for the development of anti-acne therapy via targeting NLRP3 inflammasome.