Additionally, our GO enrichment analysis revealed that signaling was an integral component of biological processes in both RA and OA: 8 DEGs (KLRD1, ITGAX, CD79A, IRS2, JAK2, SEMA4D, ITGB7, and OLFM4) screened from the RA group and 8 DEGs (LBP, CDH2, HTR2B, TNFRSF11A, ADM, TLR7, IL1B, and DUSP2) screened from the OA group played significant roles in signaling biological processes. This evidence concerns the gene SEMA4D and rheumatoid arthritis.