In serum, RA subjects with moderate/severe periodontitis had significantly higher levels of APRIL (TNFSF13) (p = 0.013), sCD30 (TNFRSF8) (p = 0.048) and gp130 (sIL-6Rß) (p = 0.01) compared to patients with no/mild form of periodontitis (Figure 1A–C). Here, TNFSF13 is linked to periodontitis.