It has long been known that, in addition to genetic factors, epigenetic effects fundamentally influence the functioning of the living organism. Although the genome of individual cells of the human body is almost identical, the access, transcription and expression of genetic information are influenced by epigenetic effects. The eukaryotic nuclear DNA is wrapped around histone octamers to form the nucleosome, the basic unit of the chromatin structure. The covalent modifications of the histone proteins cause epigenetic changes. Human conception, followed by the division and implantation of the fertilized egg into the maternal decidua, is a complex process that requires the coordinated functioning of embryological, immunological processes and anatomical structures. The steps of these processes are genetically determined and the coarse- and fine-tuning of these effects occurs at the epigenetic level by external effects such as hormones, toxins, changes in diet, infections, or cell differentiation. The most significant rearrangements occur in the embryonic period after the fertilization of the egg. In our paper, we review the literature to present the effects that influence the fine-tuning of genome function at the epigenetic level. Disturbances of these mechanisms are the basis of several pathologies that threaten conception, implantation and successful pregnancy, such as recurrent miscarriage, preeclampsia, fetal growth restriction or premature birth. In addition, epigenetic alterations acting during the period of plasticity of individual development can cause diseases that appear in the young, adult and even old age of the offspring, which can even be inherited through generations.

Background/Aim: Successful conception and pregnancy require a complex and organized communication between the embryo (allograft) and the mother’s (host) immune system. The decidual NK cells (dNK), among other leukocyte subsets, have an important role in orchestrating this immune environment. This study aimed to investigate how exposure to benign and malignant trophoblastic cell lines affects the phenotype and cytotoxic function of dNK cells. Materials and Methods: In our study, we isolated dNK cells from term, healthy human placentas and sorted them to achieve a pure, CD56 bright, CD16 negative population. These NK cells were co-cultured with HTR-8 (benign) and Jeg-3 (malignant) trophoblastic cell lines for one and five days. The NK cells were isolated again after the exposure to the trophoblastic cells, and their phenotype was assessed again. Their cytotoxicity was also measured and compared to the cytotoxicity of dNK cells not exposed to trophoblastic cells. Results: After one day of co-culture, dNK phenotype remained unchanged with both cell lines. However, a five-day exposure to Jeg-3 cells resulted in a shift toward a CD56 diminished CD16+ phenotype, resembling peripheral NK cells. Additionally, cytotoxic activity of dNK cells was significantly reduced after co-culture with both cell lines, with a more pronounced suppression observed following exposure to Jeg-3 cells. Conclusion: There are certain similarities between the immune evasion of tumor cells and the physiological invasion of the trophoblastic cells of embryonic origin into the maternal decidua. Understanding the ways of interaction between dNK cells and the trophoblastic cells may reveal similar immunological interactions between the host’s NK cells and tumor cells.

The genotype of our cells is almost the same for all cells in our body, but due to epigenetic effects, their phenotype can show significant differences. Epigenetics is a relatively new field of molecular biology that deals with the changes affecting the heritable phenotype, gene expression and gene activity in addition to the given genotype. The gene expression of immune and tumor cells is regulated by epigenetic processes. These processes can enhance the immune system evasion mechanisms of various tumor cells, while the results of other processes can actually help the immune system function. Our paper explores the epigenetic aspects of gynecological tumors through a thorough review of the Hungarian and international literature, with particular attention to the tumor processes of the cervix, uterus, ovary and breast. It also affects gestational tumors. It discusses the epigenetics of endometriosis, which does not belong to the group of classic tumor diseases, but in terms of its pathomechanism shows many similarities with other tumors. Finally, the paper discusses new findings in epigenetic medicine and therapy. Orv Hetil. 2025; 166(52): 2043–2054.