Mechanisms and Effects of Isorhamnetin on Imiquimod-Induced Psoriasiform Dermatitis in Mice

Isorhamnetin (IRh), which has a wide range of pharmacological effects, is one of the most significant active components in the fruits of Hippophae rhamnoides L. and the leaves of Ginkgo biloba L. It protects the heart and brain, in addition to possessing anti-tumor, anti-inflammatory, antioxidant, organ protection, and anti-obesity properties. We sought to assess IRh's anti-psoriatic activity, explore its immunomodulatory properties in reducing the severity of psoriatic symptoms, and evaluate its potential immunotherapeutic effects. We used IRh to treat imiquimod (IMQ)-induced psoriasis in BALB/C mice and examined the underlying mechanisms. The outcomes demonstrated that IRh reduced epidermal hyperplasia, lowered PASI scores, and improved histopathological psoriasiform lesions in IMQ-induced mice. IRh attenuated the accumulation of malondialdehyde (MDA), and also reversed the reduction caused by IMQ of superoxide dismutase (SOD) and catalase (CAT) in skin tissues. Additionally, IRh effectively inhibited IMQ's ability to increase proinflammatory cytokines such as TNF-α, IL-6, IL-17A, and transcription factor NF-κB. Furthermore, IRh significantly reduced the percentage of Th1 and Th17 in the spleens of mice treated with IMQ and suppressed the maturation of splenic dendritic cells. Overall, our research suggests that IRh protects against oxidative stress and inflammation in the pathogenesis of psoriasis, with potential for the development of new and potent medication for the treatment of psoriasis.