Testing Human Skin and Respiratory Sensitizers—What Is Good Enough?

Int. J. Mol. Sci. 2017, 18(2), 241; doi:10.3390/ijms18020241 Malmborg A., Borrebaeck C. A.K. Abstract Alternative methods for accurate in vitro assessment of skin and respiratory sensitizers are urgently needed. Sensitization is a complex biological process that cannot be evaluated accurately using single events or biomarkers, since the information content is too restricted in these measurements. […]

Int. J. Mol. Sci. 2017, 18(2), 241; doi:10.3390/ijms18020241

Malmborg A., Borrebaeck C. A.K.

Abstract

Alternative methods for accurate in vitro assessment of skin and respiratory sensitizers are urgently needed. Sensitization is a complex biological process that cannot be evaluated accurately using single events or biomarkers, since the information content is too restricted in these measurements. On the contrary, if the tremendous information content harbored in DNA/mRNA could be mined, most complex biological processes could be elucidated. Genomic technologies available today, including transcriptional profiling and next generation sequencing, have the power to decipher sensitization, when used in the right context. Thus, a genomic test platform has been developed, denoted the Genomic Allergen Rapid Detection (GARD) assay. Due to the high informational content of the GARD test, accurate predictions of both the skin and respiratory sensitizing capacity of chemicals, have been demonstrated. Based on a matured dendritic cell line, acting as a human-like reporter system, information about potency has also been acquired. Consequently, multiparametric diagnostic technologies are disruptive test principles that can change the way in which the next generation of alternative methods are designed.
Keywords:

genomics; skin sensitization; adverse outcome pathways; next generation in vitro tests

Next generation skin sensitisation testing.

Personal Care Magazine Europe, sept 2016 Malmborg Hager A., Johansson H., Lindstedt M., Borrebaeck CA.   DNA is the software that predicts human phenotypes. Genomics utilises DNA as such a piece of software, which in several recent applications has been demonstrated to be able to predict a number of biological features, enabling anything from face recognition to vaccine development. The tremendous information […]

Personal Care Magazine Europe, sept 2016

Malmborg Hager A., Johansson H., Lindstedt M., Borrebaeck CA.

 

DNA is the software that predicts human phenotypes. Genomics utilises DNA as such a piece of software, which in several recent applications has been demonstrated to be able to predict a number of biological features, enabling anything from face recognition to vaccine development. The tremendous information content, harboured in the DNA, should be harnessed in tests of cosmetic ingredients and formulations, to get a complete insight into what is happening in the body when these types of products are applied to the human skin. This type of complex information gives a holistic view of a human condition that many of us are familiar with, such as e.g. allergic contact dermatitis, and has the potential not only to classify chemicals used in cosmetics but also to determine the magnitude to which a
chemical affects the human body (the potency).

This distinguishes genomics from most other test principles, where in many cases only one or two markers are being
monitored, such as DC activation markers (CD86, CD54), genes involved in cytoprotective responses to oxidative stress or electrophilic compounds (Nrf2, Keap1), or proinflammatory cytokines, (e.g. IL18).

Next generation skin sensitisation testing. PC Magazine, Sept 2016. Malmborg Hager A., Johansson H., Lindstedt M., Borrebaeck CA.

From genome-wide arrays to tailor-made biomarker readout – Progress towards routine analysis of skin sensitizing chemicals with GARD.

Toxicol In Vitro. 2016 Dec;37:178-188. doi: 10.1016/j.tiv.2016.09.013. Epub 2016 Sep 13. Forreryd A., Zeller K., Lindberg T., Johansson H., Lindstedt M Abstract Allergic contact dermatitis (ACD) initiated by chemical sensitizers is an important public health concern. To prevent ACD, it is important to identify chemical allergens to limit the use of such compounds in various […]

Toxicol In Vitro. 2016 Dec;37:178-188. doi: 10.1016/j.tiv.2016.09.013. Epub 2016 Sep 13.

Forreryd A., Zeller K., Lindberg T., Johansson H., Lindstedt M

Abstract

Allergic contact dermatitis (ACD) initiated by chemical sensitizers is an important public health concern. To prevent ACD, it is important to identify chemical allergens to limit the use of such compounds in various products. EU legislations, as well as increased mechanistic knowledge of skin sensitization have promoted development of non-animal based approaches for hazard classification of chemicals. GARD is an in vitro testing strategy based on measurements of a genomic biomarker signature. However, current GARD protocols are optimized for identification of predictive biomarker signatures, and not suitable for standardized screening. This study describes improvements to GARD to progress from biomarker discovery into a reliable and cost-effective assay for routine testing. Gene expression measurements were transferred to NanoString nCounter platform, normalization strategy was adjusted to fit serial arrival of testing substances, and a novel strategy to correct batch variations was presented. When challenging GARD with 29 compounds, sensitivity, specificity and accuracy could be estimated to 94%, 83% and 90%, respectively. In conclusion, we present a GARD workflow with improved sample capacity, retained predictive performance, and in a format adapted to standardized screening. We propose that GARD is ready to be considered as part of an integrated testing strategy for skin sensitization.

KEYWORDS:

GARD; In vitro assay; Predictive genomic biomarker signature; Skin sensitization

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Prediction of chemical respiratory sensitizers using GARD, a novel in vitro assay based on a genomic biomarker signature.

PLoS One. 2015 Mar 11;10(3):e0118808. doi: 10.1371/journal.pone.0118808. eCollection 2015. Forreryd A., Johansson H., Albrekt AS, Borrebaeck CA, Lindstedt M. Abstract BACKGROUND: Repeated exposure to certain low molecular weight (LMW) chemical compounds may result in development of allergic reactions in the skin or in the respiratory tract. In most cases, a certain LMW compound selectively sensitize […]

PLoS One. 2015 Mar 11;10(3):e0118808. doi: 10.1371/journal.pone.0118808. eCollection 2015.

Forreryd A., Johansson H., Albrekt AS, Borrebaeck CA, Lindstedt M.

Abstract

BACKGROUND:

Repeated exposure to certain low molecular weight (LMW) chemical compounds may result in development of allergic reactions in the skin or in the respiratory tract. In most cases, a certain LMW compound selectively sensitize the skin, giving rise to allergic contact dermatitis (ACD), or the respiratory tract, giving rise to occupational asthma (OA). To limit occurrence of allergic diseases, efforts are currently being made to develop predictive assays that accurately identify chemicals capable of inducing such reactions. However, while a few promising methods for prediction of skin sensitization have been described, to date no validated method, in vitro or in vivo, exists that is able to accurately classify chemicals as respiratory sensitizers.

RESULTS:

Recently, we presented the in vitro based Genomic Allergen Rapid Detection (GARD) assay as a novel testing strategy for classification of skin sensitizing chemicals based on measurement of a genomic biomarker signature. We have expanded the applicability domain of the GARD assay to classify also respiratory sensitizers by identifying a separate biomarker signature containing 389 differentially regulated genes for respiratory sensitizers in comparison to non-respiratory sensitizers. By using an independent data set in combination with supervised machine learning, we validated the assay, showing that the identified genomic biomarker is able to accurately classify respiratory sensitizers.

CONCLUSIONS:

We have identified a genomic biomarker signature for classification of respiratory sensitizers. Combining this newly identified biomarker signature with our previously identified biomarker signature for classification of skin sensitizers, we have developed a novel in vitro testing strategy with a potent ability to predict both skin and respiratory sensitization in the same sample.

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Systematic evaluation of non-animal test methods for skin sensitisation safety assessment.

Toxicology in Vitro   Volume 29, Issue 1, February 2015, Pages 259–270 Kerstin Reisinger, Sebastian Hoffmann, Nathalie Alépée, Takao Ashikaga, Joao Barroso, Cliff Elcombe, Nicola Gellatly, Valentina Galbiati, Susan Gibbs, Hervé Groux, Jalila Hibatallah, Donald Keller, Petra Kern, Martina Klaric, Susanne Kolle, Jochen Kuehnl, Nathalie Lambrechts, Malin Lindstedt, Marion Millet, Silvia Martinozzi-Teissier, Andreas Natsch, Dirk Petersohn, […]
Toxicology in Vitro   Volume 29, Issue 1, February 2015, Pages 259–270

Kerstin Reisinger, Sebastian Hoffmann, Nathalie Alépée, Takao Ashikaga, Joao Barroso, Cliff Elcombe, Nicola Gellatly, Valentina Galbiati, Susan Gibbs, Hervé Groux, Jalila Hibatallah, Donald Keller, Petra Kern, Martina Klaric, Susanne Kolle, Jochen Kuehnl, Nathalie Lambrechts, Malin Lindstedt, Marion Millet, Silvia Martinozzi-Teissier, Andreas Natsch, Dirk Petersohn, Ian Pike, Hitoshi Sakaguchi, Andreas Schepky, Magalie Tailhardat, Marie Templier, Erwin van Vliet, Gavin Maxwell

 

Abstract

The need for non-animal data to assess skin sensitisation properties of substances, especially cosmetics ingredients, has spawned the development of many in vitro methods. As it is widely believed that no single method can provide a solution, the Cosmetics Europe Skin Tolerance Task Force has defined a three-phase framework for the development of a non-animal testing strategy for skin sensitisation potency prediction. The results of the first phase – systematic evaluation of 16 test methods – are presented here. This evaluation involved generation of data on a common set of ten substances in all methods and systematic collation of information including the level of standardisation, existing test data, potential for throughput, transferability and accessibility in cooperation with the test method developers. A workshop was held with the test method developers to review the outcome of this evaluation and to discuss the results. The evaluation informed the prioritisation of test methods for the next phase of the non-animal testing strategy development framework. Ultimately, the testing strategy – combined with bioavailability and skin metabolism data and exposure consideration – is envisaged to allow establishment of a data integration approach for skin sensitisation safety assessment of cosmetic ingredients.

Keywords

Skin sensitisationTesting strategySafety assessmentNon-animal test methodsAdverse Outcome Pathways

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Genomic allergen rapid detection in-house validation-a proof of concept.

Toxicol Sci. 2014 Jun;139(2):362-70. doi: 10.1093/toxsci/kfu046. Epub 2014 Mar 27. Johansson H., Rydnert F., Kuehnl J., Schepky A., Borrebaeck C.A.K., Lindstedt M. Abstract Chemical sensitization is an adverse immunologic response to chemical substances, inducing hypersensitivity in exposed individuals. Identifying chemical sensitizers is of great importance for chemical, pharmaceutical, and cosmetic industries, in order to prevent […]

Toxicol Sci. 2014 Jun;139(2):362-70. doi: 10.1093/toxsci/kfu046. Epub 2014 Mar 27.

Johansson H., Rydnert F., Kuehnl J., Schepky A., Borrebaeck C.A.K., Lindstedt M.

Abstract

Chemical sensitization is an adverse immunologic response to chemical substances, inducing hypersensitivity in exposed individuals. Identifying chemical sensitizers is of great importance for chemical, pharmaceutical, and cosmetic industries, in order to prevent the use of sensitizers in consumer products. Historically, chemical sensitizers have been assessed mainly by in vivo methods, however, recently enforced European legislations urge and promote the development of animal-free test methods able to predict chemical sensitizers. Recently, we presented a predictive biomarker signature in the myeloid cell line MUTZ-3, for assessment of skinsensitizers. The identified genomic biomarkers were found to be involved in immunologically relevant pathways, induced by recognition of foreign substances and regulating dendritic cell maturation and cytoprotective mechanisms. We have developed the usage of this biomarker signature into a novel in vitro assay for assessment of chemical sensitizers, called Genomic Allergen Rapid Detection (GARD). The assay is based on chemical stimulation of MUTZ-3 cultures, using the compounds to be assayed as stimulatory agents. The readout of the assay is a transcriptional quantification of the genomic predictors, collectively termed the GARD Prediction Signature (GPS), using a complete genome expression array. Compounds are predicted as either sensitizers or nonsensitizers by a Support Vector Machine model. In this report, we provide a proof of concept for the functionality of the GARD assay by describing the classification of 26 blinded and 11 nonblinded chemicals as sensitizers or nonsensitizers. Based on these classifications, the accuracy, sensitivity, and specificity of the assay were estimated to 89, 89, and 88%, respectively.

KEYWORDS:

GARD; allergic contact dermatitis; chemical sensitizers; in vitro assay; predictive assay; skin sensitization

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Human blood dendritic cell subsets exhibit discriminative pattern recognition receptor profiles

Immunology. 2014 Jun;142(2):279-88. doi: 10.1111/imm.12252. Lundberg K., Rydnert F, Greiff L, Lindstedt M. Abstract Dendritic cells (DCs) operate as the link between innate and adaptive immunity. Their expression of pattern recognition receptors (PRRs), such as Toll-like receptors (TLRs) and C-type lectin receptors (CLRs), enables antigen recognition and mediates appropriate immune responses. Distinct subsets of human […]

Immunology. 2014 Jun;142(2):279-88. doi: 10.1111/imm.12252.

Lundberg K., Rydnert F, Greiff L, Lindstedt M.

Abstract

Dendritic cells (DCs) operate as the link between innate and adaptive immunity. Their expression of pattern recognition receptors (PRRs), such as Toll-like receptors (TLRs) and C-type lectin receptors (CLRs), enables antigen recognition and mediates appropriate immune responses. Distinct subsets of human DCs have been identified; however their expression of PRRs is not fully clarified. Expressions of CLRs by DC subpopulations, in particular, remain elusive. This study aimed to identify and compare PRR expressions on human blood DC subsets, including CD1c(+) , CD141(+) and CD16(+) myeloid DCs and CD123(+) plasmacytoid DCs, in order to understand their capacity to recognize different antigens as well as their responsiveness to PRR-directed targeting. Whole blood was obtained from 13 allergic and six non-allergic individuals. Mononuclear cells were purified and multi-colour flow cytometry was used to assess the expression of 10 CLRs and two TLRs on distinct DC subsets. PRR expression levels were shown to differ between DC subsets for each PRR assessed. Furthermore, principal component analysis and random forest test demonstrated that the PRR profiles were discriminative between DC subsets. Interestingly, CLEC9A was expressed at lower levels by CD141(+) DCs from allergic compared with non-allergic donors. The subset-specific PRR expression profiles suggests individual responsiveness to PRR-targeting and supports functional specialization.

KEYWORDS:

C-type lectin receptors; Toll-like receptors; human dendritic cell subsets; pattern recognition receptors

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Evaluation of high throughput gene expression platforms using a genomic biomarker signature for prediction of skin sensitization.

BMC Genomics. 2014 May 16;15:379. doi: 10.1186/1471-2164-15-379. Forreryd A., Johansson H., Albrekt A.S., Lindstedt M Abstract BACKGROUND: Allergic contact dermatitis (ACD) develops upon exposure to certain chemical compounds termed skin sensitizers. To reduce the occurrence of skin sensitizers, chemicals are regularly screened for their capacity to induce sensitization. The recently developed Genomic Allergen Rapid Detection […]

BMC Genomics. 2014 May 16;15:379. doi: 10.1186/1471-2164-15-379.

Forreryd A., Johansson H., Albrekt A.S., Lindstedt M

Abstract

BACKGROUND:

Allergic contact dermatitis (ACD) develops upon exposure to certain chemical compounds termed skin sensitizers. To reduce the occurrence of skin sensitizers, chemicals are regularly screened for their capacity to induce sensitization. The recently developed Genomic Allergen Rapid Detection (GARD) assay is an in vitro alternative to animal testing for identification of skinsensitizers, classifying chemicals by evaluating transcriptional levels of a genomic biomarker signature. During assay development and biomarker identification, genome-wide expression analysis was applied using microarrays covering approximately 30,000 transcripts. However, the microarray platform suffers from drawbacks in terms of low sample throughput, high cost per sample and time consuming protocols and is a limiting factor for adaption of GARD into a routine assay for screening of potential sensitizers. With the purpose to simplify assay procedures, improve technical parameters and increase sample throughput, we assessed the performance of three high throughput gene expression platforms–nCounter®, BioMark HD™ and OpenArray®–and correlated their performance metrics against our previously generated microarray data. We measured the levels of 30 transcripts from the GARD biomarker signature across 48 samples. Detection sensitivity, reproducibility, correlations and overall structure of gene expression measurements were compared across platforms.

RESULTS:

Gene expression data from all of the evaluated platforms could be used to classify most of the sensitizers from non-sensitizers in the GARD assay. Results also showed high data quality and acceptable reproducibility for all platforms but only medium to poor correlations of expression measurements across platforms. In addition, evaluated platforms were superior to the microarray platform in terms of cost efficiency, simplicity of protocols and sample throughput.

CONCLUSIONS:

We evaluated the performance of three non-array based platforms using a limited set of transcripts from the GARD biomarker signature. We demonstrated that it was possible to achieve acceptable discriminatory power in terms of separation between sensitizers and non-sensitizers in the GARD assay while reducing assay costs, simplify assay procedures and increase sample throughput by using an alternative platform, providing a first step towards the goal to prepare GARD for formal validation and adaption of the assay for industrial screening of potential sensitizers.

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Prediction of skin sensitizers using alternative methods to animal experimentation.

Basic Clin Pharmacol Toxicol. 2014 Jul;115(1):110-7. doi: 10.1111/bcpt.12199. Epub 2014 Feb 18. Johansson H., Lindstedt M. Abstract Regulatory frameworks within the European Union demand that chemical substances are investigated for their ability to induce sensitization, an adverse health effect caused by the human immune system in response to chemical exposure. A recent ban on the […]

Basic Clin Pharmacol Toxicol. 2014 Jul;115(1):110-7. doi: 10.1111/bcpt.12199. Epub 2014 Feb 18.

Johansson H., Lindstedt M.

Abstract

Regulatory frameworks within the European Union demand that chemical substances are investigated for their ability to induce sensitization, an adverse health effect caused by the human immune system in response to chemical exposure. A recent ban on the use of animal tests within the cosmetics industry has led to an urgent need for alternative animal-free test methods that can be used for assessment of chemical sensitizers. To date, no such alternative assay has yet completed formal validation. However, a number of assays are in development and the understanding of the biological mechanisms of chemical sensitization has greatly increased during the last decade. In this MiniReview, we aim to summarize and give our view on the recent progress of method development for alternative assessment of chemical sensitizers. We propose that integrated testing strategies should comprise complementary assays, providing measurements of a wide range of mechanistic events, to perform well-educated risk assessments based on weight of evidence.

Skin sensitizers differentially regulate signaling pathways in MUTZ-3 cells in relation to their individual potency.

BMC Pharmacol Toxicol. 2014 Feb 11;15:5. doi: 10.1186/2050-6511-15-5. Albrekt A.S., Johansson H., Borrebaeck C.A.K., Lindstedt M. Abstract BACKGROUND: Due to the recent European legislations posing a ban of animal tests for safety assessment within the cosmetic industry, development of in vitro alternatives for assessment of skin sensitization is highly prioritized. To date, proposed in vitro […]

BMC Pharmacol Toxicol. 2014 Feb 11;15:5. doi: 10.1186/2050-6511-15-5.

Albrekt A.S., Johansson H., Borrebaeck C.A.K., Lindstedt M.

Abstract

BACKGROUND:

Due to the recent European legislations posing a ban of animal tests for safety assessment within the cosmetic industry, development of in vitro alternatives for assessment of skin sensitization is highly prioritized. To date, proposed in vitro assays are mainly based on single biomarkers, which so far have not been able to classify and stratify chemicals into subgroups, related to risk or potency.

METHODS:

Recently, we presented the Genomic Allergen Rapid Detection (GARD) assay for assessment of chemical sensitizers. In this paper, we show how the genome wide readout of GARD can be expanded and used to identify differentially regulated pathways relating to individual chemical sensitizers. In this study, we investigated the mechanisms of action of a range of skin sensitizers through pathway identification, pathway classification and transcription factor analysis and related this to the reactive mechanisms and potency of the sensitizing agents.

RESULTS:

By transcriptional profiling of chemically stimulated MUTZ-3 cells, 33 canonical pathways intimately involved in sensitization to chemical substances were identified. The results showed that metabolic processes, cell cycling and oxidative stress responses are the key events activated during skin sensitization, and that these functions are engaged differently depending on the reactivity mechanisms of the sensitizing agent. Furthermore, the results indicate that the chemical reactivity groups seem to gradually engage more pathways and more molecules in each pathway with increasing sensitizing potency of the chemical used for stimulation. Also, a switch in gene regulation from up to down regulation, with increasing potency, was seen both in genes involved in metabolic functions and cell cycling. These observed pathway patterns were clearly reflected in the regulatory elements identified to drive these processes, where 33 regulatory elements have been proposed for further analysis.

CONCLUSIONS:

This study demonstrates that functional analysis of biomarkers identified from our genomics study of human MUTZ-3 cells can be used to assess sensitizing potency of chemicals in vitro, by the identification of key cellular events, such as metabolic and cell cycling pathways.