Topical adhesive spatio-temporal nanosystem co-delivering chlorin e6 and HMGB1 inhibitor glycyrrhizic acid for in situ psoriasis chemo-phototherapy

Recently, photodynamic therapy (PDT) has gained considerable attention as a promising therapeutic approach for the treatment of psoriasis. Unfortunately, the activation of high mobility group box 1 protein (HMGB1) by PDT triggers innate and adaptive immune responses, which exacerbate skin inflammation. Herein, we combined glycyrrhizic acid (GA), a natural anti-inflammatory compound and immunomodulator derived from the herb Glycyrrhiza uralensis Fisch., with PDT actuated by the photosensitizer chlorin e6 (Ce6) by co-loading them in GA-based lipid nanoparticles coated with a catechol-modified quaternary chitosan salt (GC NPs/QCS-C). GC NPs/QCS-C exhibited high drug loading efficacy, uniform size distribution, an ideal topical adhesive property, enhanced skin retention and penetration in psoriasis-like lesions, and high intracellular uptake in epidermal cells compared with the counterparts. Subsequently, the transdermal administration of GC NPs/QCS-C followed by near-infrared laser radiation in an imiquimod-induced psoriasis-like mouse model significantly ameliorated psoriasis symptoms, promoted the apoptosis of hyperproliferative epidermal cells, and alleviated the inflammatory cascade. The significant therapeutic outcomes of GC NPs/QCS-C were attributed to the synergistic effects of GA and PDT on modulating immune cell recruitment and inhibiting dendritic cell maturation. Our results demonstrated that the topical bio-adhesive nanosystem that combines GA and Ce6 offers a synergistic chemo-phototherapeutic strategy for psoriasis treatment.