After TNF-α and IL-1β exposure, the expression levels of IDO in the T-H-SF-MSCs and T-RA-SF-MSCs significantly increased when YWHAZ (p < 0.0001 and p < 0.0001), PPIA (p < 0.0002 and p < 0.0001), and TBP (p < 0.0001 and p < 0.0001) were used for normalization (Figure 5A). Here, TNF is linked to rheumatoid arthritis.