Increased expression of IL-37 correlates with TNF-\u03b1 levels and disease stage in endometriosis patients

Abstract

BackgroundIL-37 is an anti-inflammatory cytokine that increases in several inflammatory diseases with the main inducing signal for its production being pro-inflammatory cytokines like TNF-α. We aimed to assess the correlation between peritoneal fluid levels of IL-37 and TNF-α in endometriosis patients and investigate their association with disease stage. Levels of IL-37 and TNF-α were assessed in peritoneal fluid of 50 patients with endometriosis and 23 endometriosis-free females using enzyme-linked immunosorbent assay. We also assessed serum levels of IL-37 using enzyme-linked immunosorbent assay and expression of IL-37 mRNA in peritoneal fluid cells using polymerase chain reaction.ResultsPeritoneal fluid levels of IL-37 and TNF-α were higher in endometriosis patients than in control females. Also, levels were higher in patients with late endometriosis than patients with early endometriosis. In addition, serum levels of IL-37, as well as IL-37 mRNA expression in peritoneal fluid cells, were higher in patients than controls. In endometriosis patients, peritoneal fluid levels of IL-37 positively correlated with levels of TNF-α.ConclusionCollectively, our results show increased levels of the anti-inflammatory cytokine IL-37 in endometriosis patients that correlate with levels of the pro-inflammatory cytokine TNF-α, one of the main signals for IL-37 production.