Large scale enzyme based xenobiotic identification for exposomics

Ken H Liu,Preeti Bais,Edward T Morgan,Choon M Lee,Gary W Miller,Thomas R Ziegler,Michael H Woodworth,Shuzhao Li,Young-Mi Go,Colleen S Kraft,Dean P Jones,Francisco Castellanos,Grant Singer

doi:10.1038/s41467-021-25698-x

Ken H Liu, Preeti Bais + Show 11 more

Open Access

https://doi.org/10.1038/s41467-021-25698-x

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Abstract

Advances in genomics have revealed many of the genetic underpinnings of human disease, but exposomics methods are currently inadequate to obtain a similar level of understanding of environmental contributions to human disease. Exposomics methods are limited by low abundance of xenobiotic metabolites and lack of authentic standards, which precludes identification using solely mass spectrometry-based criteria. Here, we develop and validate a method for enzymatic generation of xenobiotic metabolites for use with high-resolution mass spectrometry (HRMS) for chemical identification. Generated xenobiotic metabolites were used to confirm identities of respective metabolites in mice and human samples based upon accurate mass, retention time and co-occurrence with related xenobiotic metabolites. The results establish a generally applicable enzyme-based identification (EBI) for mass spectrometry identification of xenobiotic metabolites and could complement existing criteria for chemical identification.

Highlights

Advances in genomics have revealed many of the genetic underpinnings of human disease, but exposomics methods are currently inadequate to obtain a similar level of understanding of environmental contributions to human disease
We used pooled human liver S9 fractions based upon previous findings that they are more representative of hepatocyte metabolism compared to microsomes and are more amenable for high-throughput screening applications compared to hepatocytes[14]
The purpose of this study was to develop strategies to aid the identification of low abundance xenobiotic metabolites detected by high-resolution mass spectrometry (HRMS)

Summary

Introduction

Advances in genomics have revealed many of the genetic underpinnings of human disease, but exposomics methods are currently inadequate to obtain a similar level of understanding of environmental contributions to human disease. Exposomics methods are limited by low abundance of xenobiotic metabolites and lack of authentic standards, which precludes identification using solely mass spectrometry-based criteria. To overcome the limitation in the number of chemicals measured with targeted methods, high-resolution mass spectrometry (HRMS) uses liquid chromatography with ultra-high resolution mass spectrometry and computational methods to measure chemicals as mass spectral signals without a priori knowledge of chemical identity[3] This fills an important need to deliver -omics scale chemical data for environmental epidemiology to detect unrecognized health hazards[4] but increases the need for additional approaches for chemical identification. The results establish a method to provide authentic xenobiotic metabolites and associated stable isotopic forms for use with HRMS to improve confidence in the identification of low abundance xenobiotic metabolites in humans

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