GARD - Genomic Allergen Rapid Detection. A Testing Strategy for Assessment of Chemical Sensitizers

Abstract: The modern world is increasingly dependent of the use of chemicals. The chemical industries have greatly contributed to the high standard of living in industrialised societies, and chemical compounds surround us in everyday life. Unfortunately, a vast number of chemicals cause adverse effects on the environment and human health. One such concern is chemical hypersensitivity, which is a state caused by the human immune system. Upon exposure of certain chemical substances, the body will in some instances mount immunologic responses, giving rise to clinical symptoms such as irritation and damage on skin and impaired function of the respiratory tract. In order to limit the usage of chemical compounds that induce hypersensitivity, often referred to as sensitizers, risk and hazard assessment of chemicals are crucial. Historically, toxicological hazard assessment has been performed using animal-based test methods. However, a number of factors, both political and ethical, make animal-based test methods for assessment of sensitizers unsuitable. Because of this, the development of alternative, animal-free test methods is very high priority research. However, no validated alternative is yet available that can singlehandedly replace the animal models used to date. This thesis presents a novel in vitro assay for assessment of sensitization, called Genomic Allergen Rapid Detection – GARD. It describes the identification of a predictive genomic biomarker signature in MUTZ-3 cells, able to discriminate between cell samples stimulated with chemical skin sensitizers and non-sensitizers. These findings were used to formulate guidelines and protocols for the novel assay. The functionality and predictive performance of GARD have been demonstrated with results from predictions of blinded chemicals. In addition, GARD has been explored for the possibility to predict respiratory chemical sensitisers. The ability provide mechanistic information for two different endpoints makes GARD an attractive and unique assay for safety assessment of chemicals in an in vitro environment. In conclusion, this thesis discusses GARD in relation to trends in modern toxicology and demonstrates how accurate and safe assessment of chemical sensitizers can be performed without the use of animal experiments.