Monocytes may play a role in preeclampsia development: Study

Russia: In a recent study published in Scientific Reports, Russian researchers have found a distinctive pattern in the composition of monocytes in preeclampsia patients. 

A pathological condition called preeclampsia may occur in the second half of pregnancy. At the same time, high blood pressure and proteinuria are observed. Such a dangerous complication can lead to long-term consequences for the mother and child, increasing the risk of maternal and perinatal mortality. At the same time, scientists still do not know the causes of this pathology, the features of its course, nor the methods of its treatment.

Monocytes are innate immune cells that first circulate in the bloodstream, settle in tissues, and become macrophages. There are three types of monocytes - classical (CD14++), non-classical (CD16++) and mixed, or transitional, subpopulation.

“Preeclampsia remains the leading cause of maternal and fetal morbidity and mortality. On average, this complication occurs in 8% of pregnancies. Cells of the monocyte-macrophage system play an important role in maintaining pregnancy because they maintain tolerance to a semi-allogeneic fetus. Monocytes are divided into two main subpopulations: classical and non-classical. It can be assumed that a change in the composition of monocytes can affect those organs where monocytes come from the bloodstream, particularly the placenta. Our goal was to assess what happens to two subpopulations of monocytes in preeclampsia,” Polina Vishnyakova, PhD, Assistant at the Department of Histology, Cytology and Embryology, RUDN University.

Researchers at RUDN University studied the indicators in 33 patients. In 11 of them, the pregnancy proceeded without complications; the rest faced preeclampsia. Moreover, in 12 patients with preeclampsia, the pathology appeared early - before 34 weeks.

There was no difference in the absolute number of monocytes in normal pregnancy and pregnancy with complications. However, the proportion of classic monocytes was significantly lower in patients with late preeclampsia. RUDN scientists also conducted a transcriptomic analysis to see the genes the cells express and in what quantity. With its help, the researchers hypothesized that the cause of preeclampsia might be immunological stress, that is, the stress of the immune system. The hypothesis itself is not new, but the results obtained add arguments in its favor.

“Our results point to significant changes that occur with two opposite monocyte subpopulations in preeclampsia. Overall, our study reinforces the concept of immunological stress as a major factor contributing to preeclampsia development. Moreover, it can be tracked by changes in the transcriptome profiles of monocytes,” Polina Vishnyakova, PhD, Assistant at the Department of Histology, Cytology and Embryology, RUDN University.

Reference:

Vishnyakova, P., Kuznetsova, M., Poltavets, A. et al. Distinct gene expression patterns for CD14++ and CD16++ monocytes in preeclampsia. Sci Rep 12, 15469 (2022). https://doi.org/10.1038/s41598-022-19847-5