Epithelial Cell Line Derived from Endometriotic Lesion Mimics Macrophage Nervous Mechanism of Pain Generation on Proteome and Metabolome Levels

Endometriosis is a benign disease affecting one in ten women of reproductive age worldwide. Although the pain level is not correlated to the extent of the disease, it is still one of the cardinal symptoms strongly affecting the patients’ quality of life. Yet, a molecular mechanism of this pathology, including the formation of pain, remains to be defined. Recent studies have indicated a close interaction between newly generated nerve cells and macrophages, leading to neurogenic inflammation in the pelvic area. In this context, the responsiveness of an endometriotic cell culture model was characterized upon inflammatory stimulation by employing a multi-omics approach, including proteomics, metabolomics and eicosanoid analysis. Differential proteomic profiling of the 12-Z endometriotic cell line treated with TNFα and IL1β unexpectedly showed that the inflammatory stimulation was able to induce a protein signature associated with neuroangiogenesis, specifically including neuropilins (NRP1/2). Untargeted metabolomic profiling in the same setup further revealed that the endometriotic cells were capable of the autonomous production of 7,8-dihydrobiopterin (BH2), 7,8-dihydroneopterin, normetanephrine and epinephrine. These metabolites are related to the development of neuropathic pain and the former three were found up-regulated upon inflammatory stimulation. Additionally, 12-Z cells were found to secrete the mono-oxygenated oxylipin 16-HETE, a known inhibitor of neutrophil aggregation and adhesion. Thus, inflammatory stimulation of endometriotic 12-Z cells led to specific protein and metabolite expression changes suggesting a direct involvement of these epithelial-like cells in endometriosis pain development.