S100A9 and immunoglobulin G4-related sclerosing disease: Totally, 64 (35 up-regulated, 29 down-regulated) DEPs in saliva (Figure 1A) were identified and the top10 upregulated DEPs (rank by ratio) in IgG4-RD were SLPI, S100A12, S100A8, S100A9, CD55, LYPD3, CD59, IGHA2, APP and ANXA5.