LysoPA (20:3(5Z,8Z,11Z)/0:0), prostaglandin E2, leukotriene B4, lithocholate 3-O-glucuronide, 3-hydroxyquinine, lithocholic acid glycine conjugate, and PA(18:0/22:6(5Z,8E,10Z,13Z,15E,19Z)-2OH(7S, 17S) were found to be associated with all the main symptoms through pathogenic Escherichia coli infection, rheumatoid arthritis, PPAR signaling pathway, bile secretion, GnRH signaling pathway, and fat digestion and absorption pathways. This evidence concerns the gene PPARA and rheumatoid arthritis.