(3) Indirect ELISA was performed to determine the levels of EP1–10 in serum of SLE patients and HCs, and we found EP1, EP2, EP3, EP4, EP6, and EP10 levels were increased in SLE patients compared with HCs, while after Bonferroni correction, only EP1, EP3, EP4, and EP6 levels were elevated. Here, PTGER4 is linked to systemic lupus erythematosus.