Pink lotus flower (Nelumbo nucifera) oil extract alleviates imiquimod-induced psoriasis-like dermatitis.

Pink lotus (Nelumbo nucifera Gaertn.) contains bioactive flavonoids and alkaloids that exert anti-inflammatory and antioxidant activities, and inhibit TNF-α, IL-1β, IL-6 and NF-κB signaling pathways implicated in the pathogenesis of psoriasis. However, the effects of pink lotus flower oil (PLO) on psoriasis-like skin inflammation remain unexplored. Therefore, the present study aimed to evaluate the effects of PLO treatment on imiquimod (IMQ)-induced psoriasis-like skin inflammation in a mouse model. Briefly, BALB/c mice with IMQ-induced psoriasis were administered PLO (100 and 200 mg/kg), and the psoriasis area and severity index were measured. Histopathology, proinflammatory cytokine levels, antioxidant gene expression, oxidative stress and antioxidant marker levels, and immunoreactivity were also assessed. PLO treatment markedly reduced erythema, scaling and epidermal thickening, and suppressed keratinocyte proliferation, as evidenced by decreased proliferating cell nuclear antigen immunoreactivity, and downregulated mRNA levels of keratin-encoding genes keratin 6 (K6), K16 and K17. Moreover, PLO significantly downregulated the levels of proinflammatory cytokines, including TNF-α, IL-17A, IL-23 and IL-6, and reduced the infiltration of CD4⁺ and mast cells. Mechanistically, PLO treatment decreased phosphorylated (p)-JAK2, p-JAK3 and p-STAT3 immunoreactivity by inhibiting JAK2/JAK3/STAT3 signaling. Oxidative stress was attenuated, as evidenced by reduced malondialdehyde levels, and increased nuclear factor erythroid 2-related factor 2, Cu/Zn-superoxide dismutase (Cu/Zn-SOD), Mn-SOD, catalase and glutathione peroxidase mRNA expression levels. PLO treatment also mitigated IMQ-induced splenomegaly, and suppressed IL-1b and IL-6 expression in the spleen, and reduced IL-6 expression in the axillary lymph nodes. In conclusion, PLO treatment ameliorated IMQ-induced psoriasis by enhancing antioxidant defenses, and by inhibiting JAK2 and JAK3/STAT3 signaling, supporting its potential as a therapeutic candidate for psoriasis.