The expression of TSP-1, TGF-β1, CTGF and VEGF proteins in the supernatants from NH-FLS and HDMECs co-culture as well as RA-FLS and HDMECs co-culture were significantly up-regulated by TNF-α induction (p < 0.05, Figure 3A and Supplementary Figure 4A), thereafter As2O3 significantly suppressed the secretion at a dosage of ≥1.0 μM in a dose-dependent manner (p < 0.05, Figure 3A and Supplementary Figure 4A). This evidence concerns the gene TGFB1 and rheumatoid arthritis.