CD8 and CD4 Positive NKT Subpopulations and Immune-Checkpoint Pathways in Early-Onset Preeclampsia and Healthy Pregnancy.

Although many studies have investigated the clinical aspect of early-onset preeclampsia, our knowledge about the immunological consequences of improper placenta development is scarce. The maternal immunotolerance against the fetus is greatly influenced by the Th1 predominance developed by the mother's immune system. Thirty-two early-onset preeclamptic and fifty-one healthy pregnant women with appropriately matched gestational age were involved in our study. Mononuclear cells were separated from peripheral venous blood and the frequency of CD8⁺, CD4⁺, double positive (DP), and double negative (DN) NKT cell subpopulations was determined using multicolor flow cytometry. Following the characterization, the expression levels of different immune checkpoint receptors and ligands were also defined. Soluble CD226 levels were quantified by ELISA. Novel and significant differences were revealed among the ratios of the investigated NKT subsets and in the expression patterns of PD-1, LAG-3, TIGIT and CD226 receptors. Further differences were determined in the expression of CD112, PD-1, LAG-3 and CD226 MFI values between the early-onset preeclamptic and the healthy pregnant groups. Our results suggest that the investigated NKT subpopulations act differently in the altered immune condition characteristic of early-onset preeclampsia and indicate that the different subsets may contribute to the compensation or maintenance of Th1 predominance.

Examination of the TIGIT-CD226-CD112-CD155 Immune Checkpoint Network during a Healthy Pregnancy.

Background: The importance of immune checkpoint molecules is well known in tumor and transplantation immunology; however, much less information is available regarding human pregnancy. Despite the significant amount of information about the TIGIT and CD226 immune checkpoint receptors in immune therapies, very little research has been conducted to study the possible role of these surface molecules and their ligands (CD112 and CD155) during the three trimesters of pregnancy. Methods: From peripheral blood, immune cell subpopulations were studied, and the surface expression of immune checkpoint molecules was analyzed by flow cytometry. Soluble immune checkpoint molecule levels were measured by ELISA. Results: Notable changes were observed regarding the percentage of monocyte subpopulation and the expression of CD226 receptor by CD4+ T and NKT cells. Elevated granzyme B content by the intermediate and non-classical monocytes was assessed as pregnancy proceeded. Furthermore, we revealed an important relationship between the CD226 surface expression by NKT cells and the serum CD226 level in the third trimester of pregnancy. Conclusions: Our results confirm the importance of immune checkpoint molecules in immunoregulation during pregnancy. CD226 seems to be a significant regulator, especially in the case of CD4+ T and NKT cells, contributing to the maternal immune tolerance in the late phase of pregnancy.

Examination of the TIGIT, CD226, CD112, and CD155 Immune Checkpoint Molecules in Peripheral Blood Mononuclear Cells in Women Diagnosed with Early-Onset Preeclampsia.

Early-onset preeclampsia is a common obstetrical disease with a potential genetic background and is characterized by the predominance of Th1 immune response. However, although many studies investigated the immunological environment in preeclamptic patients, no information is available about the potential role of the TIGIT/CD226/CD112/CD155 immune checkpoint pathway. A total of 37 pregnant women diagnosed with early-onset preeclampsia and 36 control women with appropriately matched gestational age were enrolled in this study. From venous blood, mononuclear cells were isolated and stored in the freezer. Using multicolor flow cytometry T-, NK cell and monocyte subpopulations were determined. After characterization of the immune cell subsets, TIGIT, CD226, CD112, and CD155 surface expression and intracellular granzyme B content were determined by flow cytometer. Significantly decreased CD226 expression and increased CD112 and CD155 surface expression were detected in almost all investigated T-cell, NK cell, and monocyte subpopulations in women diagnosed with preeclampsia compared to the healthy group. Furthermore, reduced TIGIT and granzyme B expression were measured only in preeclamptic CD8+ T cells compared to healthy pregnant women. A decreased level of the activatory receptor CD226 in effector lymphocytes accompanied with an elevated surface presence of the CD112 and CD155 ligands in monocytes could promote the TIGIT/CD112 and/or TIGIT/CD155 ligation, which mediates inhibitory signals. We assume that the inhibition of the immune response via this immune checkpoint pathway might contribute to compensate for the Th1 predominance during early-onset preeclampsia.