Total circulating microparticle levels are increased in patients with deep infiltrating endometriosis

Study question: Are the levels of total circulating cell-derived microparticles (cMPs) and circulating tissue factor-containing microparticles (cMP-TF) increased in patients with endometriosis?

Summary answer: The levels of total cMP, but not cMP-TF, were higher in patients with endometriosis, and these were attributed to higher levels in patients with deep infiltrating endometriosis (DIE).

What is known already: Previous studies have reported elevated levels of total cMP in inflammatory conditions as well as higher levels of other inflammatory biomarkers in endometriosis. Increased expression of tissue factor (a transmembrane receptor for Factor VII/VIIa) in eutopic and ectopic endometrium from patients with endometriosis has been described. There is no previous data regarding total cMP and cMP-TF levels in patients with endometriosis.

Study design, size, duration: A prospective case-control study including two groups of patients was carried out. The E group included 65 patients with surgically confirmed endometriosis (37 with DIE lesions) and the C group comprises 33 women without surgical findings of any form of endometriosis. Patients and controls were recruited during the same 10-month period. Controls were the next patient without endometriosis undergoing surgery, after including two patients with endometriosis.

Participants/materials, setting, methods: Venous blood samples for total cMP and cMP-TF determinations were obtained at the time of surgery, before anesthesia at a tertiary care center. To assess total cMP, an ELISA functional assay was used and cMP-TF activity in plasma was measured using an ELISA kit.

Main results and the role of chance: Total cMP levels in plasma were higher in the E group compared with the C group (P < 0.0001). The subanalysis of endometriosis patients with DIE or with ovarian endometriomas without DIE showed that total cMP levels were higher in the DIE group (P = 0.001). There were no statistically significant differences in cMP-TF levels among the groups analyzed.

Limitations, reasons for caution: This is a preliminary study in which the sample size was arbitrarily decided, albeit in keeping with previous studies analyzing cMP in other inflammatory diseases and other biomarkers in endometriosis. The control group included patients with other pathologies as well as healthy controls, and blood samples were taken at different phases of the cycle.

Wider implications of the findings: Elevated total cMP levels in DIE patients may reflect an inflammatory and/or procoagulant systemic status in these patients. Further studies are warranted to confirm our findings and to assess the role of cMP levels in the pathophysiology of DIE.

Study funding/competing interests: This study was supported in part by a grant from FIS-PI11/01560 and FIS-PI11/00977 within the 'Plan Nacional de I + D + I' and co-funded by the 'ISCIII-Subdirección General de Evaluación' and 'Fondo Europeo de Desarrollo Regional (FEDER)' and by the grant 'Premi Fi de Residència Emili Letang 2015' from the Hospital Clínic of Barcelona. The authors have no competing interests to disclose.