Psoriasis is a
skin disease with autoimmune tendency, and
taxifolin is an effective
flavonoid with anti-inflammatory activity. It has been reported that
taxifolin alleviates psoriatic
dermatitis, but the detailed regulatory mechanism of keratinocyte proliferation is unclear. In this study, we revealed the mechanism of
taxifolin on
imiquimod-induced inflammatory infiltration and keratinocyte over-proliferation. Our results show that
taxifolin prevented proliferation cycle of keratinocyte in a concentration-dependent manner. Over-proliferation and abnormal apoptosis of epidermal cells were obvious in the mouse model of
psoriasis induced by
imiquimod.
Taxifolin treatment improved
erythema and scales of psoriatic lesions in mice, and reduced the proportion of CD3 + cells, especially γδT cells, in lesions and thymus. Therefore,
taxifolin decreased the expression level of IL-17A-dominated inflammatory
cytokines. Proteomic analysis showed that 30 up-regulated
proteins and 23 down-regulated
proteins were compared with the lesions before and after the treatment with
taxifolin. Among them, cytoplasmic
phospholipase A2 (cPLA2), the key
enzyme of the pro-inflammatory mediator, was the most significantly down-regulated
protein. And enriched KEGG pathway shown that
PPAR-γ pathway was most involved.
Taxifolin significantly reduced p-cPLA2 and increased
PPAR-γ
protein level in keratinocytes and lesions induced by
IL-17 and
imiquimod respectively. Meanwhile, phosphorylation of ERK and P-38 were also inhibited. These results suggest that
taxifolin prevented imiquimode-induced excessive immune activation and keratinocyte proliferation by decreasing p-cPLA2 and regulating the
PPAR-γ pathway. Our study provides new insights into the cellular regulatory mechanisms of
taxifolin in
psoriasis.