Photodynamic therapy with 5-aminolevulinic acid suppresses IFN-γ-induced K17 expression in HaCaT cells via MAPK pathway.

OBJECTIVE: Psoriasis is a chronic inflammatory skin disorder that greatly affects the patient's quality of life. Photodynamic therapy (PDT) with 5-aminolevulinic acid (ALA) has recently been applied for inflammatory dermatoses including psoriasis. However, the therapeutic effect of ALA-PDT is yet to be validated, and the underlying mechanisms remain unclear.

MATERIALS AND METHODS: In this study, a psoriatic model was established by treating HaCaT cells with 250 U/ml IFN-γ for 48 h. The effect of ALA-PDT treatment on HaCaT cell viability was assessed using MTT assay. The levels of p38, JNK, and ERK, as well as their phosphorylation status (P-p38, P-JNK, P-ERK), were assessed by immunoblotting.

RESULTS: Our data indicate that ALA-PDT can significantly inhibit the proliferation of IFN-g-treated HaCaT cells and the expression of keratin 17, both in a dose- and time-dependent manner. Furthermore, ALA-PDT can activate the MAPK pathway, and promote the expression of p38, JNK, and ERK. ALA-PDT showed pro-apoptotic effects by enhancing cell apoptosis and upregulating the apoptotic genes PARP and caspase 3.

CONCLUSIONS: Taken together, these findings indicate the possible pathways involved in ALA-PDT-mediated effects and highlight the potential of ALA-PDT in the development of novel therapeutic strategies.