Molecules known as microRNAs (miRNAs) are naturally prevalent in the body and function to control protein expression by limiting protein production. Many diseases show signs of increased production of miRNAs, indicating they have a part of disease pathogenesis. A group of researchers from Medical University of Bialystok in Poland hypothesized that endometriosis may be no different, and they conducted a study to assess miRNA expression in eutopic endometrium samples of patients. They found 136 aberrant miRNA molecules expressed in the patients compared to controls.

“The molecular changes that could potentially lead to abnormal growth of endometrium outside uterus include miRNAs expression fluctuations,” wrote Dr. P. Laudanski, lead author of “Profiling of Selected MicroRNAs in Proliferative Eutopic Endometrium of Women with Ovarian Endometriosis,” which was published in BioMed Research International. “miRNA expression is tissue- and cell-specific and it was demonstrated that miRNAs are important in endometriosis and associated reproductive conditions.”

Previously, the research group identified that two specific miRNAs, hsa-miR-483-5p and hsa-miR-629, out of 667 studied miRNAs were significantly downregulated in samples of eutopic endometrium taken from patients with ovarian endometriosis. The team wanted to expand on this previous work, as there exist many more than 667 possible miRNA molecules.

To cover a wide range of miRNAs, the team conducted the present study using locked-nucleic acid miRNA microarrays, which are the most comprehensive means of analyzing miRNAs. The technique allows more than 2000 miRNAs to be profiled, making it a powerful one. The team chose to use 3100 capture probes in the assay to evaluate miRNA expression, identifying 1198 miRNAs that were differentially expressed between control and endometriosis patients. However, only 136 were different by a fold-change of 1.3 or more.

“There are several pathways that may be potentially dysregulated, due to abnormal miRNA expression, in eutopic endometrium of patients with endometriosis and in this way contribute to its pathogenesis,” wrote Dr. Laudanski. Among the miRNAs detected are ones involved in natural killer cell cytotoxicity. Natural killer cells have been shown to be involved in endometriosis, where other studies have found their activity to be inhibited in the eutopic endometrium. If the link between miRNAs and natural killer cells is further explored, researchers may be able to find a way to enhance cell function and prevent further development of endometriosis.