SHP2‐Triggered Endothelial Cell Activation Fuels Estradiol‐Independent Endometrial Sterile Inflammation

Sterile inflammation occurs in various chronic diseases due to many nonmicrobe factors. Examples include endometrial hyperplasia (EH), endometriosis, endometrial cancer, and breast cancer, which are all sterile inflammation diseases induced by estrogen imbalances. However, how estrogen-induced sterile inflammation regulates EH remains unclear. Here, a single-cell RNA-Seq is used to show that SHP2 upregulation in endometrial endothelial cells promotes their inflammatory activation and subsequent transendothelial macrophage migration. Independent of the initial estrogen stimulation, IL1β and TNFα from macrophages then create a feedforward loop that enhances endothelial cell activation and IGF1 secretion. This endothelial cell-macrophage interaction sustains sterile endometrial inflammation and facilitates epithelial cell proliferation, even after estradiol withdrawal. The bulk RNA-Seq results and phosphoproteomic analysis show that endothelial SHP2 mechanistically enhances RIPK1 activity by dephosphorylating RIPK1^Tyr380. This event activates downstream activator protein 1 (AP-1) and instigates the inflammation response. Furthermore, targeting SHP2 using SHP099 (an allosteric inhibitor) or endothelial-specific SHP2 deletion alleviates endothelial cell activation, macrophage infiltration, and EH progression in mice. Collectively, the findings demonstrate that SHP2 mediates the transition of endothelial activation from estradiol-driven acute inflammation to macrophage-amplified chronic inflammation. Targeting sterile inflammation mediated by endothelial cell activation is a promising strategy for nonhormonal intervention in estrogen-related diseases.