Chlorin e6-mediated photodynamic therapy promotes collagen production and suppresses MMPs expression via modulating AP-1 signaling in P. acnes-stimulated HaCaT cells.

BACKGROUND: Photodynamic therapy (PDT) is a clinically approved therapeutic for cancers and non-neoplastic diseases, based on the use of a photosensitizer activated by light. The feasibility of PDT depends on several factors, such as PDT dose, photosensitizer efficacy, type of light source, and target tissue irradiated.

METHODS: In this study, the second generation photosensitizer chlorin e6 (Ce6) and halogen light were used to investigate their PDT effect on the collagen production and MMPs expression of heat killed P. acnes-stimulated HaCaT cells. The mRNA levels of COL1A1, c-Jun, and c-Fos were detected by RT-PCR. The protein levels of MMPs, ERK and JNK were detected by western blot. The transactivation of AP-1 was detected by luciferase assay.

RESULTS: Ce6-based PDT markedly upregulated the mRNA level of COL1A1 and type I procollagen level; and at the same time downregulated the expression of MMPs in P. acnes-infected HaCaT cells. Moreover, Ce6-mediated PDT, in a dose dependent manner, inhibited P. acnes-induced phosphorylation of JNK and ERK, as wells as the phosphorylation of their downstream targets c-Jun and c-Fos. P. acnes-induced mRNA expression of c-Jun and c-Fos were also suppressed by Ce6-mediated PDT. The transactivation of AP-1 induced by P. acnes infection was also downregulated.

CONCLUSION: These results indicated that Ce6-mediated PDT with halogen light enhanced collagen production, but inhibited the expression of MMPs in P. acnes-infected HaCaT cells, by regulating AP-1 signals. This investigation provided the first molecular basis for the increase in collagen production by Ce6-mediated PDT, suggesting its potential use for scar amelioration and skin rejuvenation in acne treatment.