As2O3 could also down-regulated those four proteins in supernatants of RA-FLS and HDMECs co-culture when TNF-α treatment was absent (p < 0.05, Figure 3A), however those in supernatants from NH-FLS and HDMECs co-cultures under As2O3 administration without TNF-α treatment didn’t change significantly (Supplementary Figure 4A). Here, TNF is linked to rheumatoid arthritis.