It has recently been described in a mouse model of periodontitis with RA, that the modulation of cathepsin K-mediated TLR9-related autophagy, can decrease bone destruction in periodontitis promoted by RA, by modulating the infiltration of macrophages, TLR9, autophagy proteins (TFEB and LC3) and inflammatory cytokines (149) (Figure 1G). Here, TLR9 is linked to periodontitis.