Rutaecarpine ameliorates imiquimod-induced psoriasis-like dermatitis in mice associated with alterations in the gut microbiota

Psoriasis is accepted as a chronic, inflammatory, immune-mediated skin disease triggered by complex environmental and genetic factors. For a long time, disease recurrence, drug rejection, and high treatment costs have remained enormous challenges and burdens to patients and clinicians. Natural products with effective immunomodulatory and anti-inflammatory activities from medicinal plants have the potential to combat psoriasis and complications. Herein, an imiquimod (IMQ)-induced psoriasis-like dermatitis model was established in mice. The model mice are treated with 1% rutaecarpine (RUT) (external use) or the oral administration of RUT at different concentrations. Furthermore, high-throughput 16S rRNA gene sequencing was applied to analyse the changes in the diversity and composition of the gut microbiota. Based on the observation of mouse dorsal skin changes, RUT can protect against inflammation to improve psoriasis-like skin damage in mice. Additionally, RUT could suppress the expression levels of proinflammatory cytokines (IL-23, IL-17A, IL-22, IL-6, and IFN-α) within skin tissue samples. Concerning gut microbiota, we found obvious variations within the composition of gut microflora between IMQ-induced psoriasis mice and RUT-treated psoriasis mice. RUT effectively mediates the recovery of gut microbiota in mice induced by IMQ application. Psoriasis is linked to the production of several inflammatory cytokines and gut microbiome alterations. This research shows that RUT might restore gut microbiota homeostasis, reduce inflammatory cytokine production, and ameliorate psoriasis symptoms. In conclusion, the gut microbiota might be a therapeutic target or biomarker for psoriasis that aids in clinical diagnosis and therapy.