Twenty cytokines were decreased in PBC saliva, including TNF-related cytokines (sTNF-R1, sTNF-R2, TNF-α, TNFSF12, TNFSF13B, TNFSF14), chemokines (CCL15, CCL2, IL-8/CXCL8), IL-12 family cytokines (IL-12p40, IL-35), IL-20 family cytokines (IL-19, IL-22), metalloproteases (MMP-1, MMP-2), soluble IL-6 receptors (sIL-6Rα and sIL-6Rβ), IL-1β, IL-32, and osteocalcin. Here, MMP2 is linked to primary biliary cholangitis.