Soluble ST2 and IL-33: Potential markers of endometriosis in the Tunisian population

• IL-33 levels in PF and in serum were significantly higher in patients with endometriosis compared to healthy controls.
• Soluble ST2 levels in PF were significantly different between patients and controls.
• Higher levels of IL-33 mRNA were detected in PF from patients with endometriosis.
• Significant correlation between IL-33 and sST2 levels in PF was observed.

Interleukin-33 is an IL-1 family cytokine which signals via its T1/ST2 receptor, and acts as a key regulator of inflammation. This study aims to measure the expression of soluble ST2 (sST2) and IL-33 in endometriosis. We investigated thirty women with laparoscopic and histopathological confirmed endometriosis and 20 control women without pelvic pathology. Peripheral blood mononuclear cells and peritoneal fluid (PF) were assessed for sST2 and IL-33 levels that are measured by sandwich enzyme-linked immunosorbent assay. Peritoneal fluid IL-33 mRNA expression was quantified by real-time reverse transcription polymerase chain reaction assays. We found that IL-33 levels in PF and in serum were significantly higher in patients with endometriosis compared to women without endometriosis (P < 0.05). IL-33 increased levels were significantly more important in PF [10.45 ± 14.33 ng/mL] than in serum [2.68 ± 1.54 ng/mL] from endometriosis patients. Higher levels of IL-33 mRNA expression were detected in PF from patients with endometriosis. Soluble ST2 levels in PF were significantly different between patients [2.96 ± 0.98 ng/mL; P < 0.0001] and controls [0.88 ± 0.076 ng/mL]. Serum sST2 levels were similarly expressed in endometriosis patients and in controls (P > 0.05). Significant correlation was observed between IL-33 and sST2 levels in PF. In conclusion, IL-33 and sST2 values observed in PF were found to correlate with endometriosis severity. Elevated and correlated PF IL-33 and sST2 levels from patients with endometriosis suggested a potential role as surrogate markers of disease activity.