Self-assembled nanoparticles with bilirubin/JPH203 alleviate imiquimod-induced psoriasis by reducing oxidative stress and suppressing Th17 expansion

Psoriasis is a chronic inflammatory skin disease with dysregulation of the immune system, which usually manifests as erythematous scleroma with hyperplasia of the epidermis. Although the pathogenesis remains unclear, oxidative stress and inflammation are inextricably linked during the development of psoriasis. Therefore, scavenging of ROS and suppression of inflammation may be a rational and effective strategy to ameliorate psoriasis and delay its further development. Here, a “Tanghulu”-like nanoplatform (BJN) is developed using the endogenous antioxidant bilirubin and a specific inhibitor (JPH203) of LAT1, an amino acid transporter involved in the activation of mTOR, for treatment of psoriasis by scavenging ROS and interfering with mTOR signaling, consequently blocking Th17 and IL-17 release. The nanoparticles show increased uptake in inflamed keratinocytes and display an efficient ROS scavenging capability. In an in vivo psoriasis model, BJN effectively permeate into the inflamed skin and be retained there, thereby reversing the psoriasis-specific changes in the imiquimod-induced mice as evident from suppression of keratinocyte hyperplasia and decrease in immune cell infiltration. This study shows that BJN can exert a superior anti-psoriasis effect by scavenging ROS, blocking the LAT1-mTOR pathway, inactivating immune reaction, restricting Th17 differentiation, and decreasing IL-17A secretion, offering a promising strategy for psoriasis treatment.