Intraperitoneal translocation of gut microbiota induces NETosis and promotes endometriosis

Background Endometriosis is a debilitating gynaecological disorder with an elusive pathogenesis. While gut microbiota dysbiosis has been implicated, the causal role of gut-peritoneum microbial translocation and the specific mechanisms driving disease progression remain elusive. Notably, the role of peritoneal neutrophils and neutrophil extracellular traps (NETs) in the development of endometriosis remains unknown. Objective This study aims to delineate the pathogenic pathway linking gut microbiota to peritoneal neutrophil activation and the development of endometriosis. Design We combined single-cell RNA sequencing of clinical peritoneal fluid immune cells with functional validation in heterologous and homologous mice models. We further adopted microbial source-tracking analysis of patient cohorts and interventional strategies, including faecal microbiota transplantation (FMT) and administration of green fluorescent protein (GFP)-tagged Pseudomonas aeruginosa . Results We identified a unique membrane metalloendopeptidase (MME) positive neutrophil subset (Neu_MME) that is expanded in endometriosis and primed for NETs formation (NETosis). These Neu_MME released NETs in response to bacterial lipopolysaccharides (LPS), which directly captured endometrial cells and enhanced their proliferation and migration, driving lesion development. Accordingly, inhibiting NETosis or degrading NETs significantly suppressed endometriosis in mice. Furthermore, FMT from patients with endometriosis to mice disrupted the intestinal barrier, promoting the translocation of gut microbiota, particularly Pseudomonas , into the peritoneal cavity and the lesions. This translocated Pseudomonas was identified as a key driver of LPS-induced NETosis and disease progression. Conclusion Our findings define a gut-peritoneum axis in endometriosis, where gut-derived Pseudomonas triggers NETosis in peritoneal Neu_MME to promote disease, suggesting that targeting this bacterium or NETosis represents a viable therapeutic strategy.