CXCL12 and rheumatoid arthritis: Bioinformatics analysis showed that DE piRNAs might participate in the transcriptional regulation of various RA regulatory molecules, such as STAT3, FCGR2A, CXCL12, etc. GO analysis results showed that piRNA might intervene in the disease by participating in transcriptional regulation, intracellular signal transduction, RNA polymerase II promoter transcriptional regulation, cell differentiation, and other processes, indicating that the whole functional system of piRNAs exists in RA and may change in response to disease status.