Forsythoside A Alleviates Imiquimod-Induced Psoriasis-like Dermatitis in Mice by Regulating Th17 Cells and IL-17A Expression

Abstract

Psoriasis is a recurrent inflammatory skin disease characterized by redness and scaly skin lesions with itchy or painful sensations. Forsythoside A, one of the main active compounds isolated from the fruit of Forsythia suspensa, has been widely applied to treat inflammatory diseases in the clinical use of traditional oriental medicine. However, the effect of forsythoside A on psoriasis remains unclear. This study aimed to explore the therapeutic effects and immune regulation of forsythoside A on psoriasis. C57BL/6 mice were divided into six groups and treated with imiquimod cream on their shaved back skin to induce psoriasis-like dermatitis. Different doses of forsythoside A (5 mg/kg, 10 mg/kg, or 20 mg/kg) were administered to the respective treatment groups. Skin redness, scaling, and ear thickness were measured; keratinocyte proliferation and inflammatory cytokine expression were detected by hematoxylin–eosin and immunohistochemical staining. Th17 cells in the inguinal lymph nodes were detected by flow cytometric analysis. IL-17A levels were measured using ELISA. The results showed that forsythoside A relieved psoriatic skin symptoms such as skin redness, thickness, scaling, and reduced epidermal thickening. The expression of IL-6, IL-17, and Ki-67 was downregulated in the forsythoside-A-treated groups. Th17 cell expression in inguinal lymph nodes and IL-17A secretion was suppressed by forsythoside A. In conclusion, forsythoside A was found to alleviate imiquimod-induced psoriasis-like dermatitis in mice by suppressing Th17 development and IL-17A secretion. These findings demonstrate the feasibility of forsythoside A in treating human psoriasis.

Chemical Compositions of Lianqiao (Forsythia suspensa) Extracts and Their Potential Health Benefits

“…According to these results and the literature, compound 28 was identified as forsythoside A, a type of phenylethanoid glycosides. Forsythoside A has been proven to have antioxidant, anti-inflammatory, and antiviral activities, and is known as one of the representative active substances in Lianqiao [ 17 , 18 , 19 ]. The content of forsythoside has been designated as a marker for Lianqiao’s quality control according to Chinese Pharmacopoeia (2015 Edition) [ 20 ].…”

Phytochemicals Characterization of Lianqiao (Forsythia suspensa) extract and evaluation of its antivirus and antioxidant activities

“…The content of forsythoside has been designated as a marker for Lianqiao's quality control according to Chinese Pharmacopoeia [14]. Forsythoside A has been proven to exhibit antioxidant, anti-in ammatory and antiviral activities, and is known as one of the representative active substances in Lianqiao [15][16][17]. The viral infections can induce the production of superoxide molecules, leading to oxidative stress within the host [18].…”

Forsythoside A inhibits apoptosis and autophagy induced by infectious bronchitis virus through regulation of the PI3K/Akt/NF-κB pathway

“…The activity of caspase-3 protein in BHK cells was detected using Caspase-3 Assay Kit (Beyotime Biotechnology, China). Briefly, after the BHK cells in 96-well plates were treated with FTA (10, 25, and 50 µM) and IBV (10 TCID 50 ), the 50 µL of cellular lysate supernatant, 40 µL of detection buffer, and 10 µL of caspase-3 substrate acetyl-Asp-Glu-Val-Asp p-nitroanilide (2 mM) were added into the plates and incubated for 60 min ( 40 ). The absorbance of p -nitroanilide was determined at 405 nm using a microtiter plate reader.…”