PRG2 and AQPEP are misexpressed in fetal membranes in placenta previa and percreta†

Analysis of the clinical value of serum MMP-9 and VEGF expression levels in the prenatal diagnosis of patients with aggressive placenta previa

OBJECTIVE

To investigate the diagnostic efficacy and detection value of matrix metalloproteinase-9 (MMP-9) and VEGF in menacing pernicious placenta previa (PPP).

METHOD

Among all the cases of PPP, a critical condition within the Placenta Accreta Spectrum (PAS) caused by aberrant implantation of the placenta in the uterine wall, which were analyzed between April 2021 and March 2023, there were sixty-three cases. The control group consisted of those sixty-three women who had a normal placenta. Serum levels of MMP-9 and VEGF were measured and compared in both groups. The expression levels of MMP-9 and VEGF were analyzed along with ultrasound scores related to different degrees of placental implantation. Comparisons between groups were performed using t-tests and one-way ANOVA. The diagnostic efficacy of each of the indicators was determined using receiver operating characteristic (ROC) curves by calculating the area under the curve (AUC) and Youden's index.

RESULTS

MMP-9, VEGF expression, and ultrasound scores of pregnant women in the PPP group were significantly higher than those in the control group (p < 0.05). Logistic regression analysis demonstrated that MMP-9, VEGF, and ultrasound scores were significantly associated with PPP (p < 0.05). ROC curves indicated that serum MMP-9, VEGF, and ultrasound scores predicted the AUC of 0.802, 0.817, and 0.983 for PPP, respectively. The Youden's index values were 0.492, 0.540, and 0.826, respectively.

CONCLUSION

MMP-9, VEGF, and ultrasound scores help predict placental implantation in PPP, which, in turn, provides significant support for clinical understanding.

Spatial proteomics and transcriptomics of the maternal-fetal interface in placenta accreta spectrum

In severe Placenta Accreta Spectrum (PAS), trophoblasts gain deep access in the myometrium (placenta increta). This study investigated alterations at the fetal-maternal interface in PAS cases using a systems biology approach consisting of immunohistochemistry, spatial transcriptomics and proteomics. We identified spatial variation in the distribution of CD4+, CD3+ and CD8+ T-cells at the maternal-interface in placenta increta cases. Spatial transcriptomics identified transcription factors involved in promotion of trophoblast invasion such as AP-1 subunits ATF-3 and JUN, and NFKB were upregulated in regions with deep myometrial invasion. Pathway analysis of differentially expressed genes demonstrated that degradation of extracellular matrix (ECM) and class 1 MHC protein were increased in increta regions, suggesting local tissue injury and immune suppression. Spatial proteomics demonstrated that increta regions were characterised by excessive trophoblastic proliferation in an immunosuppressive environment. Expression of inhibitors of apoptosis such as BCL-2 and fibronectin were increased, while CTLA-4 was decreased and increased expression of PD-L1, PD-L2 and CD14 macrophages. Additionally, CD44, which is a ligand of fibronectin that promotes trophoblast invasion and cell adhesion was also increased in increta regions. We subsequently examined ligand receptor interactions enriched in increta regions, with interactions with ITGβ1, including with fibronectin and ADAMS, emerging as central in increta. These ITGβ1 ligand interactions are involved in activation of epithelial-mesenchymal transition and remodelling of ECM suggesting a more invasive trophoblast phenotype. In PAS, we suggest this is driven by fibronectin via AP-1 signalling, likely as a secondary response to myometrial scarring.

Placenta: an old organ with new functions

The transition from oviparity to viviparity and the establishment of feto-maternal communications introduced the placenta as the major anatomical site to provide nutrients, gases, and hormones to the developing fetus. The placenta has endocrine functions, orchestrates maternal adaptations to pregnancy at different periods of pregnancy, and acts as a selective barrier to minimize exposure of developing fetus to xenobiotics, pathogens, and parasites. Despite the fact that this ancient organ is central for establishment of a normal pregnancy in eutherians, the placenta remains one of the least studied organs. The first step of pregnancy, embryo implantation, is finely regulated by the trophoectoderm, the precursor of all trophoblast cells. There is a bidirectional communication between placenta and endometrium leading to decidualization, a critical step for maintenance of pregnancy. There are three-direction interactions between the placenta, maternal immune cells, and the endometrium for adaptation of endometrial immune system to the allogeneic fetus. While 65% of all systemically expressed human proteins have been found in the placenta tissues, it expresses numerous placenta-specific proteins, whose expression are dramatically changed in gestational diseases and could serve as biomarkers for early detection of gestational diseases. Surprisingly, placentation and carcinogenesis exhibit numerous shared features in metabolism and cell behavior, proteins and molecular signatures, signaling pathways, and tissue microenvironment, which proposes the concept of "cancer as ectopic trophoblastic cells". By extensive researches in this novel field, a handful of cancer biomarkers has been discovered. This review paper, which has been inspired in part by our extensive experiences during the past couple of years, highlights new aspects of placental functions with emphasis on its immunomodulatory role in establishment of a successful pregnancy and on a potential link between placentation and carcinogenesis.

Mouse Surgical Model of Mechanical Uterine Injury and Subsequent Embryo Defects

Uterine injury from procedures such as Cesarean sections (C-sections) often have severe consequences on subsequent pregnancies, leading to disorders such as uterine placenta previa, placenta accreta spectrum (PAS), and Cesarean scar pregnancy. With rates of C-section at ∼30% of deliveries in the US and projected to continue to climb, an understanding of the mechanisms by which these pregnancy disorders arise and opportunities for intervention are sorely needed. However, there are currently very few animal models of uterine injury and its subsequent impacts on maternal as well as in utero and postnatal fetal outcomes. Here, we describe a procedure for a novel model of surgically induced uterine injury in the genetically tractable laboratory mouse (Mus musculus). We describe preparatory steps for surgery, the induction of uterine injury itself, and post-surgical recovery. We then provide supporting information regarding downstream dissection of pregnant mice. Lastly, we include additional information regarding estrous cycle staging in order to perform surgeries and dissections at the relevant phase in non-pregnant mice. This procedure for incurring uterine injury in a mouse model presents an important step forward in understanding uterine damage and its associated pregnancy disorders. © 2024 Wiley Periodicals LLC. Basic Protocol 1: Preparation for surgery Basic Protocol 2: Surgery and induction of uterine injury Basic Protocol 3: Mating and dissection of pregnant mice as endpoint analyses Support Protocol: Estrous staging of animals.

Human uterine natural killer cells regulate differentiation of extravillous trophoblast early in pregnancy

In humans, balanced invasion of trophoblast cells into the uterine mucosa, the decidua, is critical for successful pregnancy. Evidence suggests that this process is regulated by uterine natural killer (uNK) cells, but how they influence reproductive outcomes is unclear. Here, we used our trophoblast organoids and primary tissue samples to determine how uNK cells affect placentation. By locating potential interaction axes between trophoblast and uNK cells using single-cell transcriptomics and in vitro modeling of these interactions in organoids, we identify a uNK cell-derived cytokine signal that promotes trophoblast differentiation at the late stage of the invasive pathway. Moreover, it affects transcriptional programs involved in regulating blood flow, nutrients, and inflammatory and adaptive immune responses, as well as gene signatures associated with disorders of pregnancy such as pre-eclampsia. Our findings suggest mechanisms on how optimal immunological interactions between uNK cells and trophoblast enhance reproductive success.

Structural insights into the covalent regulation of PAPP-A activity by proMBP and STC2

Originally discovered in the circulation of pregnant women as a protein secreted by placental trophoblasts, the metalloprotease pregnancy-associated plasma protein A (PAPP-A) is also widely expressed by many other tissues. It cleaves insulin-like growth factor-binding proteins (IGFBPs) to increase the bioavailability of IGFs and plays essential roles in multiple growth-promoting processes. While the vast majority of the circulatory PAPP-A in pregnancy is proteolytically inactive due to covalent inhibition by proform of eosinophil major basic protein (proMBP), the activity of PAPP-A can also be covalently inhibited by another less characterized modulator, stanniocalcin-2 (STC2). However, the structural basis of PAPP-A proteolysis and the mechanistic differences between these two modulators are poorly understood. Here we present two cryo-EM structures of endogenous purified PAPP-A in complex with either proMBP or STC2. Both modulators form 2:2 heterotetramer with PAPP-A and establish extensive interactions with multiple domains of PAPP-A that are distal to the catalytic cleft. This exosite-binding property results in a steric hindrance to prevent the binding and cleavage of IGFBPs, while the IGFBP linker region-derived peptides harboring the cleavage sites are no longer sensitive to the modulator treatment. Functional investigation into proMBP-mediated PAPP-A regulation in selective intrauterine growth restriction (sIUGR) pregnancy elucidates that PAPP-A and proMBP collaboratively regulate extravillous trophoblast invasion and the consequent fetal growth. Collectively, our work reveals a novel covalent exosite-competitive inhibition mechanism of PAPP-A and its regulatory effect on placental function.