ALA-PDT alleviates the psoriasis by inhibiting JAK signalling pathway

Background Photodynamic therapy (PDT) with 5-aminolevulinic acid (ALA) is a well-known treatment for non-hypertrophic actinic keratoses and superficial basal-cell carcinomas. Objectives In this study, we first revealed that ALA-PDT treatment effectively ameliorated the psoriasis-like lesion in imiquimod (IMQ)-induced mouse model and further explored the potential molecular mechanism and related signalling pathways during the treatment. Besides, we also confirmed a significant alleviation of ALA-PDT therapy on IFN-γ-induced over-proliferation of keratinocytes. Methods H&E staining was conducted to reveal the histological changes of mice in different groups. The different expression levels of RNA were illustrated by using QRT-PCR. Western blot was performed to confirm the various expression levels of protein in mice. In vitro, cell proliferation and cell cycle were evaluated by cell counting kit-8 and flow cytometry assay, respectively. Results The result showed that ALA-PDT’s anti-proliferation effect and regulation on Socs1 /3, JAK1 /2 and K17 in IFN-γ-induced keratinocytes were largely weakened by NAC, indicating that ALA-PDT attenuated the proliferation of IFN-γ-induced keratinocytes by enhancing ROS level. Conclusions These results demonstrated that ALA-PDT largely activated the productivity of Socs1 /3 in a ROS-dependent manner. Socs1 /3 is a potential blocker in JAK signalling pathway and inhibits the proliferation and keratinization of keratinocytes in psoriasis.