Serum paraoxonase-1 activity in women with endometriosis and its relationship with the stage of the disease

BACKGROUND: There is increasing evidence that oxidative stress may play a role in the pathophysiology of endometriosis. Serum paraoxonase-1 (PON-1) is a high-density lipoprotein (HDL) associated enzyme that prevents oxidative modification of low-density lipoprotein (LDL). The aims of the study were to (i) compare the serum PON-1 activity in women with endometriosis versus controls and (ii) assess whether PON-1 activity can be used as a diagnostic test for endometriosis. METHODS: A total of 87 women who underwent laparoscopy or laparotomy were divided into groups by visual diagnosis at surgery: control patients (n = 40) with no pathologic findings; endometriosis sufferers with minimal to mild (n = 24) and moderate to severe (n = 23) stage. Serum PON-1 activity was measured spectrophotometrically. Lipid hydroperoxide (LOON) levels were measured by iodometric assay. Serum triglyceride (TG), total cholesterol (TC), HDL and LDL levels were also determined. RESULTS: PON-1 activity was significantly lower whereas LOON levels were significantly higher in women with moderate to severe endometriosis than in women with minimal to mild endometriosis and controls, and in women with minimal to mild endometriosis compared with control groups (P < 0.0001, for all). A significant negative correlation was found between PON-1 activity and stage of the disease (r= -0.74, P < 0.0001). PON-1 activity and HDL levels were decreased whereas LOOH, TG, TC and LDL levels increased in all women with endometriosis versus controls (all P < 0.0001). CONCLUSIONS: Reduced serum PON-1 activity and increased LOOH might contribute to the increased susceptibility for the development of atherosclerosis. PON-1 activity can be used as a diagnostic test to detect endometriosis.