Iron overload-induced ferroptosis in CD8⁺ T cells leads to functional abnormalities that promote endometriosis progression.

Abstract

Endometriosis (EM) exhibits localised iron overload. However, the contribution of ferroptosis to EM pathogenesis remains unclear. We investigated how iron overload affects CD8⁺ T cell immune function and the underlying ferroptotic mechanisms. We collected eutopic and ectopic endometrial tissues from 57 patients with stage III-IV EM and eutopic tissues from 31 controls. Iron deposition was assessed by Prussian blue staining; CD8⁺ T cell infiltration by immunohistochemistry; and ferroptosis in CD8⁺ T cells by immunofluorescence and flow cytometry. In vitro and in vivo assays measured CD8⁺ T cell ferroptosis and endometrial stromal cell apoptosis via flow cytometry. Transwell assays evaluated cell migration. Gene and protein expression were analysed via RT-qPCR and Western Blot. We verified the effect of iron overload on the growth of lesions in vivo by constructing a mouse EM model. The role of CD8⁺ T cells in EM progression was tested using a reinfusion model. In ectopic EM lesions, CD8⁺ T cells were enriched yet functionally impaired, showing increased ferrous iron accumulation and lipid peroxidation alongside decreased GPX4 expression. In vitro, iron overload reduced CD8⁺ T cell viability, elevated lipid peroxidation, and induced mitochondrial damage-effects reversed by ferroptosis inhibitors. Iron overload upregulated p53 and downregulated xCT and GPX4; p53 inhibition blocked ferroptosis, indicating a p53-dependent pathway. In vivo EM models confirmed that excess iron compromises CD8⁺ T cell function and impairs their recruitment to lesion sites. Iron overload induces p53-mediated inhibition of xCT/GPX4, triggering ferroptosis in CD8⁺ T cells and leading to their dysfunction. These insights into ferroptosis-CD8⁺ T cell interactions in EM may guide the development of novel immunotherapeutic strategies.