Jose, CA). Cytokine levels were determined using 13-plex Cytometric bead arrays
(CBA) from Biolegend (San Diego, CA). Mass-spectrometry reagents were sourced
from various vendors as follows: J.T. Baker Ultra LC/MS-grade acetonitrile
(ACN), methanol (MeOH), and water were purchased from VWR International (Radnor,
PA). LC/MS Ultra-grade formic acid (Fluka) was purchased from Sigma-Aldrich
(Saint Louis, MO, USA). Internal standards 2,2,4,4-D4 cholic acid,
2,2,4,4-D4 deoxycholic acid, 2,2,4,4-D4chenodeoxycholic acid, 2,2,4,4-D4 ursodeoxycholic acid, and
2,2,4,4-D4 lithocholic acid were purchased from Cambridge Isotope
Laboratories (Andover, MA USA). 2,2,4,4-D4 taurocholic acid was
purchased from AlsaChim (France). Millipore Amicon Ultrafree PTFE membrane
centrifugal filters (0.2 μm), and Millipore Amicon Ultra 0.5 mL 3,000
MWCO centrifugal filters were purchased from Thermo Fisher Scientific (Waltham,
MA USA)