To demonstrate the STING-IRF7-LCN2 axis formation in patients with chronic endometritis, the immunohistochemical staining of STING, IRF7, LCN2 and MC4R were detected, and the results showed these expressions had accumulated in the endometrium of chronic endometritis patients, which supports that STING-IRF7-LCN2 axis was activated during endometrial inflammation (Figure 7A; Supplementary Figure 5A–D). Here, MC4R is linked to chronic endometritis.