APOA2 and rheumatoid arthritis: In addition, RHOA was decreased in the SZ group, which was in line with the trend of pathogenesis, so RHOA was selected as the target protein of pathogenic Escherichia coli infection pathway. The protein targets of the other 5 key pathways were screened by the same method, and the rheumatoid arthritis pathway was TNFSF13, the PPAR signaling pathway was APOA2, the bile secretion pathway was ATP1A1, the GnRH signaling pathway was PRKCD, the fat digestion and absorption pathway was FABP1.