Quantification of Gut and Inflammation Markers

Levels of REG3α, TFF3, I-FABP (intestinal fatty acid binding protein), and IL-22 in plasma samples were quantified using the Human REG3α DuoSet ELISA Kit, Human TFF3 DuoSet ELISA kit, Human I-FABP DuoSet ELISA kit, and Human IL-22 Quantikine ELISA kit (R&D Systems, Minneapolis, MN), respectively, according to the manufacturer’s instructions. Plasma levels of sCD14, sCD163, LPS-binding protein (LBP), and IL-6 were quantified using the Human CD14 Quantikine Kit, the Human CD163 Quantikine Kit, the Human LBP DuoSet ELISA Kit, and the IL-6 High Sensitivity Quantikine ELISA kit (R&D Systems, Minneapolis, MN), respectively, as previously described (Li et al., 2017 (link), Li et al., 2019 (link), Xia et al., 2020 (link)). Plasma LPS levels were determined using the PYROGENT-5000 Kinetic Turbidimetric Limulus Amebocyte Lysate Assay (Lonza, Walkersville, MD) as previously described (Li et al., 2019 (link)). Plasma concentrations of 45 cytokines/chemokines/growth factors were measured using the Cytokine/Chemokine/Growth Factor 45-Plex Human ProcartaPlex Panel 1 (ThermoFisher Scientific, Waltham, MA) as previously described (Li et al., 2019 (link)).