Metabolic Profiling and Compound-Class Identification Reveal Alterations in Serum Triglyceride Levels in Mice Immunized with Human Vaccine Adjuvant Alum

Alum
has been widely used as an adjuvant for human vaccines; however,
the impact of Alum on host metabolism remains largely unknown. Herein,
we applied mass spectrometry (MS) (liquid chromatography–MS)-based
metabolic and lipid profiling to monitor the effects of the Alum adjuvant
on mouse serum at 6, 24, 72, and 168 h post-vaccination. We propose
a new strategy termed subclass identification and annotation for metabolomics
for class-wise identification of untargeted metabolomics data generated
from high-resolution MS. Using this approach, we identified and validated
the levels of several lipids in mouse serum that were significantly
altered following Alum administration. These lipids showed a biphasic
response even 168 h after vaccination. The majority of the lipids
were triglycerides (TAGs), where TAGs with long-chain unsaturated
fatty acids (FAs) decreased at 24 h and TAGs with short-chain FAs
decreased at 168 h. To our knowledge, this is the first report on
the impact of human vaccine adjuvant Alum on the host metabolome,
which may provide new insights into the mechanism of action of Alum.