Increased concentrations of soluble tumour necrosis factor receptor (sTNFR) I and II in peritoneal fluid from women with endometriosis

Tumour necrosis factor alpha (TNF alpha), a proapoptotic cytokine, is known to be present in peritoneal fluid from women with endometriosis. An emerging view is that soluble TNF receptors (sTNFR) can modulate the effects of TNF alpha by acting as TNF alpha antagonists. To assess the relevance of sTNFRs in the pathophysiology of endometriosis, concentrations of sTNFR I, sTNFR II and TNF alpha in peritoneal fluid from women with endometriosis (n = 53) and without endometriosis (n = 40) were measured. Concentrations of both sTNFR I and sTNFR II in peritoneal fluid from women with endometriosis were significantly higher than in peritoneal fluid from women without endometriosis, both in the follicular and the luteal phases. TNF alpha concentrations did not differ in patients with and without endometriosis in both phases. When stratified by the stage of the disease, women with both stages I/II and stages III/IV exhibited significantly higher concentrations of sTNFR I and sTNFR II in peritoneal fluid, compared with women without endometriosis, whereas no appreciable difference in the concentrations was detected between stages I/II and stages III/IV. A significant correlation was found between the concentrations of sTNFR I and sTNFR II; while the correlations between TNF alpha and sTNFR I or sTNFR II, were either not significant or were very weak. Furthermore, mRNA for the membrane-associated TNF receptor type 1 and TNF receptor type 2, both of which convey the effects of TNF alpha, were shown to be expressed in endometriotic tissues as well as eutopic endometrium. Together, these findings suggest a possible involvement of sTNFRs in the pathophysiology of endometriosis.