Olivia Larne, Ulrika I Torstensdotter Mattson, Rikard Alm, and Gunilla Grundström.
SenzaGen, Lund, Sweden.
The GARD®skin assay is an in vitro assay developed for the assessment of skin sensitizers. It is based on SenzaCells™, a human dendritic-like cell line, and a biomarker signature analyzed by a prediction model including pattern recognition and machine learning.
During the development of the GARD®skin platform, two solvents were used: DMSO (0.1%) and water. To increase the applicability domain of GARD®skin and the possibility to dissolve certain test items, for e.g. hard to dissolve substances and UVCBs, where show a broader range of solvents compatible with GARD®skin. Also, use of higher concentrations of the tested solvents were explored for the possibility to increase test item concentrations.
GARD®skin compatible solvents:
Increased applicability domain.
Poster publication at Eurotox, Helsinki, Sep 9, 2019.
Toxicological Sciences, kfz108, https://doi.org/10.1093/toxsci/kfz108
Henrik Johansson, Robin Gradin, Angelica Johansson, Els Adriaens, Amber Edwards, Veronika Zuckerstätter, Anders Jerre, Florence Burleson, Helge Gehrke, Erwin Roggen
Proactive identification of chemicals with skin sensitizing properties is a key toxicological endpoint within chemical safety assessment, as required by legislation for registration of chemicals. In order to meet demands of increased animal welfare and facilitate increased testing efficiency also in non-regulatory settings, considerable efforts have been made to develop non-animal approaches to replace current animal testing.
GARD™, GARD™skin, in vitro, sensitization, chemical sensitizers
Article on line ahead of print with open access
Wiley Online Library, First published: 21 April 2019, https://doi.org/10.1111/cod.13294.
Renato I. de Ávila Danillo F. M. C. Veloso Gabriel C. Teixeira Thaisângela L. Rodrigues Tim Lindberg Malin Lindstedt Simone G. Fonseca Eliana M. Lima Marize C. Valadares
Allergic contact dermatitis reported to henna‐based hair coloring products (HPs) has been associated with adulteration of henna with p‐phenylenediamine (PPD).
To develop a testing approach based on in vitro techniques that address key events within the skin sensitization adverse outcome pathway to evaluate allergenic potential of HPs.
The following in vitro assays were used to test the sensitizing capacity of hair dye ingredients: micro‐direct peptide reactivity assay (mDPRA); HaCaT keratinocytes‐associated IL‐18 assay; U937 cell line activation test (USENS)/IL‐8 levels; blood monocyte‐derived dendritic cell test; genomic allergen rapid detection (GARD skin). Those techniques with better human concordance were selected to evaluate the allergenic potential of ten HPs.
Contrasting to the label’s information, chromatographic analyses identified PPD in all products. The main henna biomarker, lawsone, was not detected in one of 10 the products. Among the techniques evaluated by testing HDIs, mDPRA, IL‐18 assay, GARD skin and U‐SENS correlated better with human classification (concordances 91.7 to 100%) and were superior to the animal testing (concordance 78.5%). Thus, these assays were used to evaluate HPs, which were classified as skin sensitizers using different two‐out‐of‐three approaches.
Our findings highlight toxicological consequences and risks associated of the undisclosed use of PPD in henna‐based “natural” “real‐life” products.
This article is protected by copyright. All rights reserved.
To replace a test animal, which is clearly a complex system with blood and organs, you need a more holistic approach to model the entire allergic response within the body. Our CEO Anki Malmborg Hager explains the benefits of using alternative testing methods to prove product safety in this week’s Manufacturing Chemist.
Int. J. Mol. Sci. 2019, 20(3), 666; https://doi.org/10.3390/ijms20030666
Gunilla Grundström and Carl A.K. Borrebaeck
There is an increasing demand for alternative in vitro methods to replace animal testing, and, to succeed, new methods are required to be at least as accurate as existing in vivo tests. However, skin sensitization is a complex process requiring coordinated and tightly regulated interactions between a variety of cells and molecules. Consequently, there is considerable difficulty in reproducing this level of biological complexity in vitro, and as a result the development of non-animal methods has posed a major challenge. However, with the use of a relevant biological system, the high information content of whole genome expression, and comprehensive bioinformatics, assays for most complex biological processes can be achieved. We propose that the Genomic Allergen Rapid Detection (GARD™) assay, developed to create a holistic data-driven in vitro model with high informational content, could be such an example. Based on the genomic expression of a mature human dendritic cell line and state-of-the-art machine learning techniques, GARD™ can today accurately predict skin sensitizers and correctly categorize skin sensitizing potency. Consequently, by utilizing advanced processing tools in combination with high information genomic or proteomic data, we can take the next step toward alternative methods with the same predictive accuracy as today’s in vivo methods—and beyond.
David W Roberts, Liverpool John Moores University, Liverpool
Introduction – Non-Animal Prediction: the 21st Century Consensus
Because of the biological complexity of the skin sensitisation process no single in chemico or in vitro assay will be an appropriate replacement for an animal-based assay such as LLNA or GPMT…
…to ensure a mechanistic basis and cover the complexity, multiple methods should be integrated into a testing strategy, in accordance with the adverse outcome pathway that describes all key events in skin sensitisation.
We need an ITS based on the KEs of the AOP…but
Is that what we really need?
A single assay, GARD™, predicts sensitisation potential and absence of sensitisation potential better than any of, or combinations of, the OECD guideline assays DPRA, KeratinosensTM (ARE-Nrf2 ) and h-CLAT.
We do not really need an ITS covering all KE’s of the AOP.
Regulatory Toxicology and Pharmacology, Volume 98, October 2018, Pages 155-160, https://doi.org/10.1016/j.yrtph.2018.07.014.
- Prediction of skin sensitization potential does not need multiple assays representing Key Events of the AOP.
- This has been argued on theoretical grounds and is now tested against published data.
- A single assay, GARD™, can outperform combinations of OECD test guideline assays.
It is shown here that GARD™ alone outperforms each of DPRA, ARE-Nrf2 luciferase or h-CLAT, alone or in any combination as a 2 out of 3 strategy, in terms of sensitivity, specificity and accuracy.
Based on the datasets analysed here, the sensitivity and specificity of GARD™ alone are 90–92% and 79–84% (“2 out of 3”, 86% and 76%). Thus, in any situation where the 2 out of 3 strategy is considered adequate, GARD™ alone could be used with equal or better performance.
Article on line
Don’t miss the interesting article in Chemical Risk Manager in Chemical Watch, written by Dr. Emma Davies, with the title; Skin sensitization integrated testing strategies need rethink, expert suggests.
Emma Davies is interviewing the UK academic Dr. David Roberts after his publication of an article in Regulatory Toxicology and Pharmacology in July where he is discussing the relevance of Integrated Testing Strategy (ITS) for skin sensitization testing as well as he is presenting data on the performance of the GARDskin test method compared to the OECD -tests.
In short, David Roberts from Liverpool John Moores University questions the science behind integrated testing strategies (ITS) for combining in vitro test methods to predict skin sensitisation, as required by REACH. Instead, Roberts suggests, ”… that the genomic allergen rapid detection (GARD) assay for skin sensitisation may outperform other OECD validated test methods, either alone or in combination.”
Dr. David Roberts will present his data and the research behind the article at the EUSAAT meeting 23-26 September in Linz, and at the ESTIV conference 15-18 October in Berlin
Read the article here (requires subscription to Chemical Watch):
Jenvert RM, Larne O, TorstensdotterMattssonU. I., Johansson H, SenzaGen, Lund, Sweden
The Genomic Allergen Rapid Detection (GARD) assay is a state of the art in vitro assay developed for the assessment of skin sensitizers. It is based on gene expression analysis of SenzaCells, a human myeloid cell line, after stimulation by the test item.
During the development of the GARD platform, two solvents were used; DMSO (0.1%) and Water. To increase the applicability domain of GARD® and the solubility of certain test items, for e.g. Medical Device extracts and UVCBs, we here show a broader range of solvents compatible with GARD.
Here, we show that the GARD® platform is compatible with the following solvents:
• Super refined olive oil