Psoriasis is a chronic immune-mediated skin disease characterized by the infiltration of multiple inflammatory cells and abnormal differentiation of keratinocytes in the skin. The treatment of psoriasis is primarily based on immunosuppressive drugs; however, their long-term use can lead to various adverse effects. Euphorbia humifusa Willd. (EuH) is used in traditional Chinese medicine for its anti-inflammatory properties and effects on skin diseases such as psoriasis.
Aim of the study
This study aimed to evaluate the anti-psoriasis effects of EuH extract, and explore its underlying mechanisms.
Methods and materials
The main components of EuH extract were analyzed using ultra-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-QTOF-MS/MS) technology. Then, we administered EuH extract to imiquimod-induced psoriasis mice for 6 consecutive days, and evaluated the effects according to the psoriasis area and severity index (PASI), spleen index, histological analysis, immunohistochemical and immunofluorescence staining, quantitative reverse-transcription polymerase chain reaction (qRT-PCR), and flow cytometry analysis. The potential mechanism was revealed using RNA sequencing (RNA-seq) and validated by target prediction, ELISA, qRT-PCR and western blot (WB) analysis.
Results
The UPLC-QTOF-MS/MS analysis showed that phenolics were the essential components in the water extracts of EuH, including flavonoids, phenolic acids, and gallotannins. Treatment with EuH alleviated psoriatic symptoms including skin condition, high PASI scores (erythema, scaling, and thickness), and spleen index values in imiquimod-induced mice. EuH treatment also inhibited keratinocyte hyperproliferation, reduced epidermal thickness, reduced inflammatory cell infiltration into skin lesions, decreased the mRNA levels of inflammatory factors, and restored T and Treg cellular balance in the spleen. RNA-seq, ELISA, qRT-PCR and WB analyses indicated that EuH extract reduced the inflammatory response and keratinocyte hyperproliferation by inhibiting the IL-17 signaling pathway.
Conclusions
Our findings suggest that EuH extract suppresses keratinocyte hyperproliferation and inflammation in psoriasis by inhibiting the IL-17 signaling pathway, supporting EuH as a potential treatment for psoriasis.
