KEGG analysis showed that these key genes were mainly involved in inflammatory bowel disease (STAT4, HLA-DPB1, HLA-DRA, STAT6, FOXP3, HLA-DPA1), cell adhesion molecule pathways (CD8B, HLA-DPB1, PDCD1, HLA-DPA1), JAK-STAT signaling pathways (STAT4, STAT6), and the T cell receptor signaling pathway (PDCD1) (Fig. 9B). Here, PDCD1 is linked to inflammatory bowel disease.