In vitro testing strategy for assessing the skin sensitizing potential of "difficult to test" cosmetic ingredients.

Before placing a new cosmetic ingredient on the market, manufacturers must establish its safety profile, in particular assessing the skin sensitization potential, which is a mandatory requirement for topical applications. Since the ban on animal testing in Europe, and its extension to many parts of the world, a battery of in vitro tests covering the key steps of the Adverse Outcome Pathway (AOP) for skin sensitization is recommended. To date, three in vitro methods are validated in the OECD guidelines (442C, 442D, 442E), and many others are under validation by OECD (2019) and ECVAM.

Assessment of phototoxicity in pigmented Long-Evans rat: sparfloxacin and 8-methoxypsoralen.

The aim of the present work was to evaluate the effects of photo-activated toxicity induced after administration of two known melanin-binding phototoxic compounds, sparfloxacin (SPX) and 8-methoxypsoralen (8-MOP), followed or not by UVA/Vis exposure, in pigmented rats (Long Evans: LE) and albino rats (Sprague Dawley: SD). Groups of three rats were treated with SPX or 8-MOP by oral gavage for six consecutive days. Irradiated animals were submitted to a UVA/Vis light dose standardized to 10 J/cm UVA daily.

Allergic skin inflammation induced by chemical sensitizers is controlled by the transcription factor Nrf2.

Allergic contact dermatitis (ACD) is induced by low-molecular weight electrophilic chemicals and metal ions. Chemical contact sensitizers trigger reactive oxygen species production and provoke electrophilic stress, leading to the accumulation of the transcription factor nuclear-related factor 2 (Nrf2) in innate immune cell types. The objective of this work was to identify the role of Nrf2 in the regulation of ACD.