Depending on the light dose and concentration of photosensitizer for photodynamic treatment (PDT), a multitude of dose-related events are demonstrable in PDT-treated cells. Sublethal doses may result in the alteration of cytokine release and consequently modify immune actions, rather than cause cell death.
The purpose of this study was to investigate cytokine expression in cultured HaCaT cells after intense pulse light (IPL) treatment or PDT utilizing 5-aminolevulinic acid (ALA) and IPL at sublethal doses.
Cultured HaCaT cells were treated with either IPL only (4, 8 and 12 J/cm2) or ALA-IPL PDT (100µmol/L of ALA; 0, 4, 8, and 12 J/cm2 of IPL). The expression of IL-10, TGF-β1 and TNF-α was investigated by reverse transcription-polymerase chain reaction and enzyme linked immunosorbent assay.
IL-10 protein increased up to 5.95-fold after IPL treatment and up to 2.85-fold after PDT. TGF-β1 mRNA and protein showed slight increases after both IPL treatment and PDT, of which the latter induced slightly larger increases. TNF-α mRNA and protein showed no induction or reduction after PDT.
Increased expressions of IL-10 and TGF-β1 was observed after PDT. The induction of IL-10 may contribute to the anti-inflammatory effect, which explains the therapeutic benefit of PDT for inflammatory dermatoses, and that of TGF-β1 may be related to the therapeutic effect for psoriasis. The finding that IL-10 induction was more marked after IPL treatment than after PDT suggests that other mechanisms than IL-10 induction in keratinocytes after PDT may participate in the anti-inflammatory effect of PDT.
Keywords: IL-10, Keratinocyte, Photodynamic therapy, TGF-β1, TNF-α