Pregnancy is a state where high and stage-dependent plasticity of the maternal immune system is necessary in order to equilibrate between immunosuppression of harmful responses towards the fetus and ability to fight infections. TCR γδ cells have been implicated in the responses in infectious diseases, in the regulation of immune responses, and in tissue homeostasis and repair. The variety of functions makes γδ T cells a particularly interesting population during pregnancy. In this study, we investigated the proportion, phenotype and TCR γ and δ repertoires of γδ T cells at the maternal–fetal interface and in the blood of pregnant women using FACS, immunohistochemistry and spectratyping. We found an enrichment of activated and terminally differentiated pro-inflammatory γδ T-cell effectors with specific location in the human decidua during early pregnancy, while no significant changes in their counterparts in the blood of pregnant women were observed. Our spectratyping data revealed polyclonal CDR3 repertoires of the δ1, δ2 and δ3 chains and γ2, γ3, γ4 and γ5 chains and oligoclonal and highly restricted CDR3γ9 repertoire of γδ T cells in the decidua and blood of pregnant women. Early pregnancy induces recruitment of differentiated pro-inflammatory γδ T-cell effectors with diverse TCR repertoires at the maternal–fetal interface.

The main role of HLA-G is to protect the semi-allogeneic embryo from immune rejection by proper interaction with its cognate receptors on the maternal immune cells. Spontaneous abortion is the most common adverse pregnancy outcome, with an incidence rate between 10% and 15%, with immunologic dysregulation being thought to play a role in some of the cases. In this study, we aimed to detect the membrane and soluble HLA-G molecule at the maternal–fetal interface (MFI) and in the serum of women experiencing missed abortion (asymptomatic early pregnancy loss) in comparison to the women experiencing normal early pregnancy. In addition, the proportion of T cells and their cytotoxic profile was evaluated. We observed no difference in the spatial expression of HLA-G at the MFI and in its serum levels between the women with missed abortions and those with normal early pregnancy. In addition, comparable numbers of peripheral blood and decidual total T and γδT cells were found. In addition, as novel data we showed that missed abortion is not associated with altered extravilous invasion into uterine blood vessels and increased cytotoxicity of γδT cells. A strong signal for HLA-G on non-migrating extravilous trophoblast in the full-term normal placental bed was detected. In conclusion, HLA-G production at the MFI or in the blood of the women could not be used as a marker for normal pregnancy or missed abortions.

The role of human leukocyte antigen F (HLA-F) at the maternal-fetal interface (MFI) during viral infection and its regulation by interferon signaling remains poorly understood. Here, we investigated HLA-F expression and regulation in first-trimester trophoblast cells following activation of the type I interferon pathway and viral infection. We demonstrate that HLA-F is significantly upregulated at both mRNA and protein levels in response to Poly(I:C) and IFN-β in a dose- and time-dependent manner, suggesting its regulation as an interferon-stimulated gene (ISG). Zika virus (ZIKV) infection similarly induced HLA-F upregulation over time. In contrast, HSV-2 infection downregulated HLA-F mRNA while maintaining steady protein levels, indicative of virus-specific regulatory mechanisms. Moreover, we identified a soluble HLA-F secreted following Poly(I:C) stimulation. These findings reveal that HLA-F is dynamically regulated in trophoblasts during viral challenge and type I IFN signaling activation, supporting its broader immunomodulatory role in antiviral defense and immune tolerance at the MFI.

The role of human leukocyte antigen F (HLA-F) at the maternal–fetal interface (MFI) during viral infection and its regulation by interferon signaling remains poorly understood. Here, we investigated HLA-F expression and regulation in first-trimester trophoblast cells following activation of the type I interferon pathway and viral infection. We demonstrate that HLA-F is significantly upregulated at both mRNA and protein levels in response to Poly(I:C) and IFN-β in a dose- and time-dependent manner, suggesting its regulation as an interferon-stimulated gene (ISG). Zika virus (ZIKV) infection similarly induced HLA-F upregulation over time. In contrast, HSV-2 infection downregulated HLA-F mRNA while maintaining steady protein levels, indicative of virus-specific regulatory mechanisms. Moreover, we identified a soluble form of HLA-F secreted following Poly(I:C) stimulation. These findings reveal that HLA-F is dynamically regulated in trophoblasts during viral challenge and type I IFN signaling activation, supporting its broader immunomodulatory role in antiviral defense and immune tolerance at the MFI.

Maternal–fetal tolerance mechanisms are crucial during human pregnancy to prevent the immune rejection of the embryo. A well-known mechanism blocking NK-cell cytotoxicity is the interaction of their inhibitory killer-cell immunoglobulin-like receptors (iKIR) with HLA-C molecules on the target cells. In this study, we aimed to investigate the expression of iKIRs (KIR2DL1 and KIR2DL2/3) on the matched decidual and peripheral γδT cells and the localization of HLA-C ligands throughout human pregnancy. The degranulation of γδT cells of pregnant and non-pregnant women in the presence of trophoblast cells was evaluated as well. Our results showed a higher proportion of iKIR-positive γδT cells at the maternal–fetal interface early in human pregnancy compared to the paired blood of pregnant women and full-term pregnancy decidua. In accordance, HLA-C was intensively expressed by the intermediate cytotrophoblasts and decidua-invading extravillous trophoblasts (EVTs) in early but not late pregnancy. Decidual γδT cells during early pregnancy showed higher spontaneous degranulation compared to their blood pairs, but neither decidual nor peripheral γδ T cells increased their degranulation in the presence of Sw71 EVT-like cells. The latter were unable to suppress the higher cytotoxicity of γδT cells, suggesting a complex regulatory landscape beyond NK-like activity inhibition.

Mesenchymal stem/stromal cells (MSCs) derived from adult and perinatal tissues exhibit distinct biological and stemness characteristics due to their different developmental origins. These differences are reflected in their proliferative capacity, differentiation potential, and the expression of key pluripotency-related transcription factors: OCT4A, SOX2, and NANOG. We examined protein-level expression and localization of these factors in early-passage adipose tissue-derived MSCs (AT-MSCs) and umbilical cord-derived MSCs (UC-MSCs). OCT4A was more prevalent in UC-MSCs, while SOX2 was higher in AT-MSCs, and NANOG was predominantly expressed in a small subpopulation (~3%) of cells obtained from both sources. OCT4A was mainly localized in the nucleus, whereas SOX2 and NANOG showed mixed nuclear and perinuclear localization. Notably, UC-MSCs exhibited higher proliferative potential, which correlated with higher OCT4 levels. These findings reveal differences in the expression of the pluripotency-related transcription factors OCT4A and SOX2 depending on the source, whereas NANOG exhibits comparable expression levels across the studied MSCs.