Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.07.31.209106v1?rss=1 Authors: Gibson, D. A., Collins, F., De Leo, B., Hotne, A. W., Saunders, P. Abstract: Objective: To characterise peritoneal macrophage populations in women with suspected endometriosis and assess if they are correlated with severity of pelvic pain symptoms. Design: Flow cytometry analysis of peritoneal fluid samples and clinical data. Setting: University Research Institute. Patients: Clinical questionnaires, surgical data and peritoneal fluid were collected with informed consent from women undergoing diagnostic laparoscopy for suspected endometriosis (n=54). Intervention(s): None Main Outcome Measure(s): Severity of pelvic pain symptoms was assessed by the EHP-30 questionnaire. Immune cells recovered from peritoneal fluid were analysed by flow cytometry. Results: Pain scores (pain domain of EHP30) did not differ according to endometriosis diagnosis, stage of endometriosis or whether or not women were receiving hormone treatment. Analysis of immune cells in peritoneal fluid revealed two populations of peritoneal macrophages: CD14high and CD14low which were not altered by menstrual cycle phase or hormone treatment. CD14high peritoneal macrophages were increased in women with endometriosis compared to those without but were not altered by coincident reproductive health issues such as infertility or heavy menstrual bleeding. Peritoneal macrophage phenotype correlated with pelvic pain symptoms in women with suspected endometriosis. Notably, CD14high peritoneal macrophages negatively correlated with pain scores whereas CD14low peritoneal macrophages were positively correlated. This association was independent of endometriosis diagnosis. Conclusion: Peritoneal macrophage phenotypes correlate with pelvic pain symptoms in women with suspected endometriosis and are altered by presence of disease. These results provide new insight into the association between endometriosis pathophysiology and pelvic pain symptoms. Copy rights belong to original authors. Visit the link for more info