POTENT ANTI-IMIQUIMOD-INDUCED PSORIASIS OF FORMULATED CITRUS PEEL EXTRACT IN MICE

Chi-Chen Lin¹, Ye-Chin Lin¹,Michiko Suzawa², Shiming Li³, Chi-Tang Ho³

¹Institute of Biomedical Science, National Chung-Hsing University, Taichung, Taiwan, Republic of China; ²Miyauchi Citrus Research Center, Shigoka-Machi, Takasaki, Gunma, 370-0845, Japan; ³Department of Food Science, Rutgers University, New Brunswick, NJ 08901, USA

Keywords: Psoriasis, Gold lotion (GL), IL-17, IL-22, IL-6, imiquimod, inflammation

Background: Psoriasis is a chronic inflammatory skin disorders affecting 2 to 3% of the worldwide population. The lesion is usually characterized by raised erythematous scaly plaques, skin infiltration with leukocytes, epidermal hyperproliferation (acanthosis), aberrant differentiation of keratinocytes (parakeratosis), and increased tortuous capillaries (angiogenesis). Initially, psoriasis was defined as a chronic-relapsing T helper (Th1)-1 type disease based on elevated levels of IFN-gamma, TNF-alpha, and IL-12. Later on, a functional role of IL-23/Th17 in the immunopathogenesis of psoriasis was demonstrated. Gold lotion (GL), a formulated product made from the peels of six citrus fruits (navel orange, citrus hassaku, citrus limon, citrus natsudaidai, citrus miyauchi iyo, and Satsuma), has been confirmed to have the bioactivities of antioxidation, anti-inflammation and immunomodulatory; however, its effects on psoriasis are unknown.

Objective: This study aims to determine the in vivo effects of GL in imiquimod-induced psoriasis form skin inflammation in mice.

Methods: BALB/c mice were given oral administration with GL and imiquimod cream was applied to the shaved back skin for seven consecutive days.

Results: We report that imiquimod (IMQ)-induced epidermal hyperplasia and psoriasis like-inflammation was significantly inhibited following GL treatment. Real-time PCR showed that mRNA levels of IL-17A, IL-17F, IL-22, IL-1ß, IL-6, and TNF-α cytokines were decreased significantly by GL application. In addition, we found that GL reduced infiltrations of CD3⁺ T cells, GR-1⁺ cells, and neutrophils in lesional skin and reduced the percentage of Th17 in the spleen.

Conclusion: The results presented herein provided a basis for GL to be used in the treatment of psoriasis in the future.