Abstract
Paeoniflorin (PF) has been reported to be effective against several skin disorders, such as allergic contact dermatitis and psoriasis; however, it remains unclear whether PF can protect against urticarial lesions. Herein, the effects of PF on rats with urticarial lesions and the possible underlying mechanism were investigated. The effects of PF administration on a rat model of ovalbumin-induced urticarial-like lesions were evaluated via pathological analysis using hematoxylin-eosin staining. Toluidine blue staining was performed to detect mast cells and ELISA was performed to determine serum histamine levels. PF-induced regulatory effects on autophagic activity and the potential underlying mechanism of this were also investigated using transmission electron microscopy, immunohistochemistry and reverse transcription-quantitative PCR. It was demonstrated that PF suppressed allergic and inflammatory responses to improve urticarial lesions, as evidenced by the attenuation of pathological abnormalities, mast cell infiltration and histamine secretion. Mechanistically, PF treatment was found to markedly limit the production and release of inflammatory cytokine interleukin (IL)-23, while the levels of IL-17 remained unchanged. PF intervention led to an increased number of autophagosomes, along with higher levels of light chain 3B (LC3B) and Beclin-1, and lower levels of P62, indicating that PF could augment autophagic activity in urticarial lesions. PF treatment increased the expression of liver kinase B1 (LKB1) and AMP-activated protein kinase-α (AMPK-α), contributing to the PF-enhanced autophagic activity. In conclusion, PF could effectively improve urticarial lesions by inhibiting inflammatory cytokine IL-23 and increasing the autophagic activity via the LKB1/AMPK-α pathway.