GDF15 and rheumatoid arthritis: RA (n = 11) had signs of inflammation compared to HD before D1 with a significantly higher GDF-15 (median 944 pg/mL, p < 0.0001), calprotectin (median 33600 pg/mL, p = 0.012), and IL-6 (median 14.2 pg/mL, p = 0.032) but not for C3a, CXCL4, Galectin-9, IP-10, LBP, MPO, sCD163 and Zonulin (Supplementary Figures S2A, B).