New Presentation: Determination of Protein Haptenation by Chemical Sensitisers within the Complexity of the Human Skin Proteome


Skin sensitisation associated with the development of allergic contact dermatitis (ACD) occurs via a number of specific key events at the cellular level. The molecular initiating event (MIE), the first in the sequence of these events, occurs after exposure of the skin to an electrophilic chemical, causing the irreversible haptenation of proteins within skin. Characterisation of this MIE is a key step in elucidating the skin sensitisation adverse outcome pathway and is essential to providing parameters for mathematical models to predict the capacity of a chemical to cause sensitisation. As a first step to addressing this challenge, we have exposed complex protein lysates from a keratinocyte cell line and human skin tissue with a range of well characterised sensitisers, including dinitrochlorobenzene (DNCB), 5-chloro-2-methylisothiazol-3-one (MCI), cinnamaldehyde (CA) and the non (or weak) sensitiser 6-methyl coumarin (6-MC). Using a novel stable isotope labelling approach combined with ion mobility assisted data independent mass spectrometry (HDMSE), we have characterised the haptenome for these sensitisers. Although a significant proportion of highly abundant proteins were haptenated, we also observed the haptenation of low abundant proteins by all three of the chemical sensitisers tested, indicating that within a complex protein background, protein abundance is not the sole determinant driving haptenation, highlighting a relationship to tertiary protein structure and the amino acid specificity of these chemical sensitisers and sensitiser potency. We have developed and tested a sensitive and robust method to study low level in vitro haptenation in relevant tissues and cell lines.

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