Transcriptomic Changes during early endometriotic lesion development - PROJECT SUMMARY Endometriosis is a non-malignant disorder defined by the presence of endometrial-like tissue outside the uterus and is associated with debilitating pelvic pain and impaired fertility. Retrograde menstruation is a primary etiologic pathway. The on-average 7-10 years between the onset of symptoms and definitive diagnosis of endometriosis places an enormous emotional and financial burden on both the patient and the healthcare system. Despite the significant health care costs and long-term health risks associated with endometriosis, its molecular etiology remains largely unknown, and non-invasive diagnostic and non-hormonal treatment options remain elusive. Therefore, a critical need exists to understand the pathogenesis of endometriotic lesions, which will ultimately lead to early treatment interventions and prevention of disease progression. Although, most studies on endometriosis have focused only on adults, patients with endometriosis report that their pain symptoms emerged during adolescence and young adulthood. Our baboon model has provided significant insight into the early pathophysiology of the disease and the mechanisms associated with aberrant gene expression. Furthermore, the peritoneal disease induced in our baboon model phenocopies changes associated with endometriosis in women including transcriptomic changes in the eutopic endometrium and lesion gene expression. Therefore, the Specific Aims of this proposal are to integrate single cell, spatial, and bulk transcriptomics analyses of peritoneal endometriotic lesions at 12 months after the induction of disease in the baboon and explore translation of these discoveries to human adolescents at early stages of endometriosis. Specifically, in Aim 1 we will determine the early inflammatory transcriptomic events in peritoneal endometriotic lesions by single cell and spatial transcriptomics analyses in our baboon model at 12 months of disease and correlate these changes with spatial transcriptomics analysis of endometriotic lesions from adolescent patients with endometriosis at 12-months post- onset of symptoms. In Aim 2 we propose to identify new drug candidates using Reversal of Gene Expression Score (RGES) to compute a drug’s potency to reverse disease gene expression based on bulk RNA-seq gene expression signatures from baboon lesions and human superficial peritoneal lesions from adolescent patients within 12 months since onset of symptoms. Drugs, filtered to target cells/pathways identified as pathologically relevant, will be tested in an endometriotic spheroid model of invasion followed by RNA-sequencing of spheroid epithelium to validate the mechanism of action. Successful completion of this research project will identify the key inflammatory transcriptomic changes over time in endometriotic lesions during their early developmental timepoints and will pave the way for early biomarker discovery, and identification of drugs for targeted therapies, which will be of direct relevance to the early disease identification and treatment for women with endometriosis.