Non-invasive diagnostics of endometriosis based on plasma miRNA expression

Aim . To develop a method for noninvasive diagnosis of external genital endometriosis based on plasma microRNA concentrations. Materials and Methods . 80 women of reproductive age who were admitted to the gynecological department for routine laparoscopy were retrospectively examined, according to the results of which and histological examination, the patients were divided into 2 groups: the main group — 54 patients with laparoscopically and histologically confirmed external genital endometriosis (EGE); the control group — 26 patients without EGE. Before laparoscopy, a blood sample was taken from all patients for a molecular-biological study of the expression of 10 microRNAs: miR-183, miR-125b, miR-126, miR-16, miR-15a, miR-200a, miR-20a, miR-21, miR-222 and miR-29b. Identification of the studied and normalizing RNAs (U6 RNA and 103a microRNA) was performed according to the method of Chen et al. The presented values of the expression of the studied microRNAs are given in the form of 2-ΔCt. The expression ratio is given in the form of 2-ΔCt (main)/2-ΔCt (control), if the expression in the group of patients with endometriosis exceeded that in the control group, and in the form of 2-ΔCt (control)/2-ΔCt (main), if vice versa. Results . Comparison of the expression of 10 mi-croRNAs between the two groups revealed statistically significant differences only in miR-183: its expression in patients with EGE was statistically 1.5 times higher than that in women of the control group (p=0.017). We have not detected a difference in the expression of mir-200a, while according to other researchers, representatives of the mir-200 family are among the most frequent whose expression changes with endometriosis. MIR-16 expression also did not differ statistically among the patients we examined, whereas a group of American colleagues revealed its increase in patients with endometriosis and with endometriosis-associated ovarian tumors. We found no difference in mir-21 expression. The results of other researchers are contradictory: some found its increase in endometrioid cysts compared with eutopic endometrium, an increase in the epithelium of the fallopian tubes with their endometriosis compared with unaffected; others did not reveal a difference between the eutopic endometrium of endometriosis patients and healthy women, but showed a decrease in expression in peritoneal foci and foci of deep infiltrative endometriosis compared with eutopic endometrium. The expression of mir-222 was reduced in the patients we examined with endometriosis, which goes against the existing ideas about the pro-oncogenic role of this microRNA. An increase in its expression in cancer of the stomach, bladder, liver, lungs, breast, endometrium, ovaries is described. At the same time, the oncosuppressive effect of mir-222 is also known in prostate cancer, squamous cell carcinoma of the oral cavity. Conclusion . Taking into account the revealed statistically significant difference in microRNA expression by ROC analysis, we determined their effectiveness and specificity in the diagnosis of EGE. Of course, further studies with a large contingent of patients are needed to confirm the diagnostic value of these biomarkers. In addition, our study did not allow us to establish a statistical difference in microRNA expression in patients with impaired fertility. But it is the test that makes it possible to differentiate female infertility — associated with endometriosis and without it, as a rule, tubal-peritoneal genesis — that will become a key tool in the personalized management of patients with infertility. In our work, the distribution of patients by stages of EGE turned out to be uneven (there were no women with stage I at all) and it was not possible to establish a statistical difference in microRNA expression depending on the "length of service" of the disease.