Evaluation of different oxidative stress biomarkers in endometriosis

Endometriosis is an estrogen-dependent chronic inflammatory disease in which oxidative stress is one of the key factors for the disease progression. Our aim was to assess oxidative stress parameters secondary to chronic inflammation in women with endometriosis by the determination of tissue thiol groups (GSH), lipid peroxidation (LOOH) and the expression of different genes related to oxidative stress (heme oxygenase-1 (HO-1), inducible nitric oxide synthase (iNOS) and inflammation (IL-6 and IL-1β). GSH and LOOH were determined by spectrophotometric analysis whereas HO-1, iNOS, IL-6 and IL-1β gene expressions were determined by real time PCR. Our results showed that GSH was significantly reduced in endometriosis group compared to controls; whereas LOOH were surprisingly lower in the endometriosis group. No significant differences were observed in GSH and LOOH levels among the different stages of the disease. In addition, our results showed that HO-1, iNOS, IL- 6 and IL-1β genes were more expressed in the endometriosis group. In particular IL-6 was significantly higher in the moderate groups compared to mild and severe group whereas IL- 1β was significantly higher in the mild group compared to moderate and severe. Furthermore, oxidative stress and inflammatory biomarkers were not dependent on the localization of the disease. Taken all together, our data suggest that oxidative stress is increased in endometriosis and it is not depending on the stadiation or localization of the disease whereas oxidative stress-related gene expression is depending on the stage of the disease.