Development of a multiparametric in vitro model of skin sensitization

Abstract

Most animal experiments on cosmetics safety are prohibited and since March 2013, this obligation includes sensitization tests. However, until now there has been no validated alternative in vitro method. In this work, 400 compounds used in the cosmetic industry were selected to cover the greatest diversity of structures, biological activities and sensitizing potential. These molecules were submitted to a series of tests aimed at reproducing essential steps in sensitization and to distinguish between sensitization and irritations, i.e., transcutaneous permeation (factor A), haptenation (factor B), sensitization cytokines production (factor C) and acute toxicity (factor D). The transcutaneous diffusion was measured on human skin explants using Franz cells. Haptenation was tested in solution on human serum albumin. Sensitization cytokine production was investigated by measurement of interleukin-18 release by keratinocytes. Acute toxicity was determined using an 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide(75) cell viability test. As only sufficiently stable, soluble and detectable compounds are usable, 33, 72, 68 and 68 molecules were finally tested on factors A, B, C and D, respectively, and 32 were completely screened by the four factors. The individual correlation of the four factors with the reference in vivo tests was limited but the combination of these factors led to a correlation between in vivo and in vitro assays of 81.2% and the safety of the test (risk of false negative) reached 96.8%. The techniques employed are simple and inexpensive and this model of four tests appears as a promising technique to evaluate in vitro the skin sensitization potential of unknown molecules.

Predicting full thickness skin sensitization using a support vector machine

“…This supports the recent notion that a molecular signature or a battery of assays needs to be implemented together to correctly identify potential contact allergens (Bauch et al, 2012; Guyard-Nicodeme, 2014). The true predictive power of our specific molecular signature will need to undergo validation studies with an expanded panel of chemicals.…”

“…There is evidence that assays that use of epidermal equivalents may be more amenable to inter-laboratory transfers to generate reproducible results than submerged cell lines that are more sensitive to specific culture conditions (Gibbs et al, 2013; Teunis et al, 2013). Ultimately, it is clear that a single assay and cellular metric of sensitization is insufficient as a stand-alone predictor and tiered strategies using a battery of assays improved the overall accuracy of identifying known skin sensitizers (Bauch et al, 2012; Guyard-Nicodeme, 2014). Thus, we envision this type of co-culture system to be utilized as a second tier assay following in silico or peptide binding screening methods.…”

Integrated decision strategies for skin sensitization hazard

“…An IDS incorporates all of the available and pertinent information about a test substance to arrive at a conclusion regarding a potential hazard. Combining outputs from several data sources minimizes the limitations of each individual assay, and the predictive power of the combination of methods may be increased compared with stand‐alone tests (Natsch et al , ; Bauch et al , ; Jaworska et al , ; Nukada et al , ; Tsujita‐Inoue et al , ; van der Veen et al , ; Guyard‐Nicodeme et al , ; Urbisch et al , ; Takenouchi et al , ). In the case of skin sensitization, several in vitro tests targeting key events in the AOP are already available [i.e.…”

Desenvolvimento de epiderme humana reconstruída (RHE) como plataforma de testes <i>in vitro</i> para irritação, sensibilização, dermatite atópica e fotoimunossupressão

“…Atualmente, há uma tendência mundial na busca pela redução, refinamento ou substituição dos ensaios em animais, e assim, ensaios como o ensaio do linfonodo local (LLNA, do inglês, Local lymph node assay) foram desenvolvidos visando a redução do uso de animais para ensaios de sensibilização (ANDERSON; SIEGEL; MEADE, 2011). Em contrapartida, para validação do potencial de sensibilização in vitro não existem modelos completamente validados (GUYARD-NICODÈME et al, 2015). Cada uma das metodologias alternativas in vitro validadas disponíveis atualmente detecta eventos pontuais da etapa de indução da sensibilização, como por exemplo, a reatividade com proteínas (DPRA), a ativação de queratinócitos (KeratinoSense) e a ativação das células dendríticas (h-CLAT) (BASKETTER; MAXWELL, 2007;GERBERICK et al, 2007).…”

“…Cada uma das metodologias alternativas in vitro validadas disponíveis atualmente detecta eventos pontuais da etapa de indução da sensibilização, como por exemplo, a reatividade com proteínas (DPRA), a ativação de queratinócitos (KeratinoSense) e a ativação das células dendríticas (h-CLAT) (BASKETTER; MAXWELL, 2007;GERBERICK et al, 2007). Assim, o desenvolvimento de um modelo completo para estudo de potencial de sensibilização cutânea apresenta-se como um desafio imediato e importante para a indústria cosmética (GUYARD-NICODÈME et al, 2015).…”