Sector 600

The blood sampling procedures were described in detail for this cohort in (Sha et al., 2022) (link). Briefly, blood samples were collected in EDTA tubes, between 9:00 am and 12:00 pm, and immediately transported to the laboratory on ice. Samples were centrifuged into plasma and immediately frozen at -80 °C until analysis. The laboratory analyses were performed by staff who were blinded to all clinical parameters. IL1β, IL-6, and TNF-α levels were run on a Sector 600 (K15049D, Meso Scale Diagnostics, Rockville, MD, USA) following manufacturer's instructions as previously published (Achtyes et al., 2020) (link). Inter-assay coefficients of variation (% CV) were: IL-1β (3.5 %), IL-2 (3.0 %), IL-6 (2.2 %), IL-8 (2.4 %), IL-10 (1.8 %), and TNF-α (2.8 %). Tryptophan (TRP), kynurenine (KYN), KYNA, and QUIN were analyzed as previously described (Achtyes et al., 2020) (link). Also, three metabolite ratios were used as derivative predictors; the KYN/TRP (rKT), QUIN/KYNA (rQK), and PIC/QUIN (rPQ) are used as estimates of the differential activity of specific enzymatic steps/branches of the pathway. Note that the absolute levels of cytokines and metabolites in the full cohort have been published previously (Sha et al., 2022) (link).