Untargeted Metabolomics of Archived Dried Blood Spots Reveals Lipid Modulation at Birth Associated with Pediatric Acute Lymphoblastic Leukemia

摘要

Acute lymphoblastic leukemia (ALL) is the most common form of childhood leukemia. Metabolomics analysis of archived dried blood spots (DBS) collected at birth provides a snapshot of early life exposures that can provide insights into the causes and underlying prenatal biology of ALL. We received single 4.7-mm DBS punches (equivalent to ～8 μL whole blood) collected between 1985 and 2005 for over 300 ALL cases and their matched controls as part of the California Childhood Leukemia Study. Matching was performed on date of birth and gender and roughly matched on ethnicity. DBS were extracted with acetonitrile and analyzed with an Agilent 1290 UHPLC system connected to a 6550 QTOF HRMS (Santa Clara, US) in ESI (-) mode. Analysis was performed on subjects stratified by age at diagnosis as a means of distinguishing between potentially different ALL phenotypes (early: 1-5 years; late: 6-14 years). In order to minimize the number of false positives, associations between metabolite features and ALL were determined with an ensemble of statistical methods, namely, linear regression p-values, bootstrapped regularized logistic regression (LASSO), and random forest. There was no overlap in features selected for associations with early diagnosis (9 features) and late diagnosis (24 features) of ALL. Annotated metabolites were primarily fatty acid and glycerophospholipids. Several of the selected metabolites were associated with the time to ALL diagnosis, suggesting that they reflect effects of disease progression rather than causal exposures. Interestingly, several metabolites selected in the late diagnosis group were highly associated with breastfeeding practice, a known risk factor of ALL. Since DBS are collected within 48 hours of birth, they include nutrients from one or more infant feedings. These results suggest that lipids associated with neonatal nutrition may be involved with initiation of ALL in early life and should be a focus of future targeted research.