Determination of antigen levels: t-plastin, transgelin and ca-125 as potential biomarkers in baboons with induced endometriosis

Abstract

Endometriosis is defined as the presence of endometrial-like tissue outside the uterine cavity and is associated with chronic intra-pelvic inflammation. Its symptoms, which are often severe, have a negative impact on a woman’s quality of life. They include chronic pelvic pain and infertility. It is estimated that about 10% of women in their reproductive ages are affected by the disease globally. Currently, diagnostic methods are laparoscopy with histological confirmation and non-invasive methods such as ultrasound and Magnetic Resonance Imaging (MRI) for advanced disease. Serum biomarkers such as CA-125 is known to be elevated in endometriosis, however, it does not have sufficient diagnostic power as a single biomarker of endometriosis. Due to this fact, there is a need to determine other antigens that would act as potential biomarkers for endometriosis. It has been observed that Transgelin and T-Plastin are upregulated in endometriosis lesions and endometrium during the secretory phase respectively in women. There is insufficient data available showing the concentration of T-plastin in serum or plasma in the development of endometriosis. The main objective of this study was to determine whether T-plastin, Transgelin and CA-125 are potential biomarkers in early diagnosis of endometriosis using baboon model for endometriosis. The baboon model represents clinically relevant research models for endometriosis. This study compared the levels of T-plastin, Transgelin and CA-125 in the peripheral blood and peritoneal fluid of baboons before and after induction of endometriosis. In this experimental design study, ten female baboons (Papio anubis, 9-15 kg each) of proven fertility, that had at least one menstruation during captivity, were induced by intra-pelvic injection of menstrual endometrium on day 1 or 2 of menstruation. This was followed by staging laparoscopy. Serum and peritoneal fluid samples were collected prior to induction to serve as controls. T-Plastin, Transgelin and CA-125 were measured using commercially available ELISA Kits. Data was analyzed using non-parametric test and level of significance determined at p<0.005. T-Plastin and Transgelin had insignificant p values in both peripheral blood and peritoneal fluid. However CA-125 showed a p- value of 0.0003 in peripheral blood between pre induction and 1st post induction sampling while the p-value in peritoneal fluid was equal to 0.0279. Diagnostic performance of individual biomarkers was determined by Receiver Operating Characteristic (ROC) with the Area under the curve (AUC) equal to 0.5 showing T-Plastin and Transgelin in both serum and peritoneal fluid were unreliable for use as biomarkers in endometriosis unless combined with other antigen. Levels of CA-125 in peritoneal fluid had an AUC of 0.7900 indicating it can be used as potential biomarkers for endometriosis in combination with other antigens. An evaluation of the three antigens using different body fluids and different methods would enhance possibility of them being used as potential biomarkers.