Evaluation of expression levels of innate lymphoid cells in preeclamptic placentas

Objective: Preeclampsia is a disease associated with poor placentation and immune tolerance. Many studies have determined that Innate Lymphoid Cells (ILC) play a role in the reorganization of spiral arteries, ensuring immune tolerance, adapting decidua to pregnancy, and homeostasis. It is not known whether the expression levels in the placenta change in the preeclampsia compared to normal pregnancy. We think that there may be differences in the expression of ILCs in preeclamptic pregnancies compared to normal pregnancies, with the hypothesis that the levels of expression of ILCs in the placenta in preeclampsia will affect trophoblast invasion and cause abnormalities in the reorganization of the spiral arteries, thus disrupting homeostasis and causing abnormalities in blood pressure. Method: Control group (term placenta samples, n=6), mild preeclampsia group (term placenta samples, n=6), and severe preeclampsia group (term placenta samples, n=6) were formed. Normal and preeclamptic placenta morphologies by hematoxylin-eosin staining were determined. Flow cytometry experiments were performed for ILC1, ILC2, and ILC3 types to determine the numerical value of ILCs present in placentas in preeclamptic and healthy pregnancies. Results: Morphologically, preeclamptic placentas are characterized by numerous syncytial nodes, fibrin deposits, areas of calcification, and trophoblast cell shedding. According to our flow cytometry results, there was no difference between the groups in the expression of ILC1s (p>0.05). When ILC2 expression was compared with the control group, it showed a statistically significant increase (p<0.05) in mild and severe preeclampsia groups. ILC3 expression showed a statistically significant increase (p<0.05) in the severe preeclampsia group compared to the control. Conclusion: While the expression of ILC1 does not differ in preeclamptic placentas compared to healthy placentas, there is an increase in the number of ILC2 and ILC3 cells. Especially as the severity of preeclampsia increases, the increase in the number of ILC3 cells becomes more statistically significant.