Photobiomodulation (PBM) emerges as a valuable fast-growing technology in the treatment of numerous skin conditions using low levels of visible or near infrared light to stimulate healing of the skin or reduce its inflammation. Since we have previously shown that the transcription factor Nrf2 controls the skin inflammatory response induced by contact allergens, we investigated the role of Nrf2 in the anti-inflammatory effect of PBM.
Primary human epidermal keratinocytes (KCs), HPEK were treated with 2,4-dinitrochlorobenzene (DNCB), an electrophilic compound described as a strong sensitizer inducing "xenoinflammation”, and were illuminated with two wavelengths (3 J/cm2): 660 nm (red) or 520 nm (green). Nrf2 pathway in response to PBM in normal and stressed KCs was investigated.
Our results revealed an increase of Nrf2 accumulation, measured by western blot, in untreated KCs illuminated with either wavelength. This accumulation is noticeably increased in illuminated DNCB- stimulated KCs. Regarding the target antioxidant genes of Nrf2, PBM induced the expression of HO1 and GCLC, 3h after illumination of DNCB-stimulated KCs with either of the two wavelengths, as shown by RT-qPCR. In terms of inflammatory response, we measured less TNF-α, IL-6 and IL-8 expression in illuminated DNCB-stimulated KCs compared to non-illuminated stressed KCs. Given that Nrf2 regulates the redox state of the cells, reactive oxygen species (ROS) production has been investigated by measuring H2O2 levels after illumination of normal or DNCB- stimulated KCs. Our results showed that PBM seems to slightly reduce the oxidative stress in DNCB-stimulated 1h after their illumination.
Our preliminaries data suggest that PBM may control inflammation response through Nrf2 activation. Nrf2 invalidation in KCs model will allow us to support the role of Nrf2 in controlling the anti-inflammatory response of PBM.

ESDRLB007 - Role of Nrf2 in the skin anti-inflammatory response induced by photobiomodulation

50th Annual Meeting of the European Society for Dermatological Research. VIRTUAL MEETING