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Introduction:Superimposed preeclampsia (SPE) occurs in 25-40% of pregnant women affected by chronic hypertension and is associated with adverse maternal and neonatal outcomes. In previous studies, we have demonstrated that pregnant Stroke-prone Spontaneously Hypertensive Rat represent a spontaneous SPE model, characterized by defective trophoblast invasion and placental oxidative stress, asymmetric fetal growth restriction and worsening maternal hypertension with renal dysfunction towards term. Here, we sought to evaluate the therapeutic potential of alpha lipoic acid (ALA), a potent antioxidant, during early pregnancy in this model.Methods:Congenic timed breedings were established using SHRSP and Wistar Kyoto (WKY) females (10-12 weeks old, 200-250 g body weight, N = 10 animals/day analyzed). Upon vaginal plug detection (gestation day (GD)1), dams were assigned to two groups: ALA treatment, injected 25mg/kg body weight ALA i.p. on GD1, GD8 and GD12 and controls, receiving saline following the same protocol. Systolic blood pressure (SBP) profiles throughout pregnancy were recorded using a noninvasive volume pressure recording device. On GD20, animals were euthanized and fetoplacental specimens isolated for morphological and molecular analyzes. Statistical analysis was run on GraphPad Prism v 8.0, using 2 way ANOVA. Statistical significance was set at p˂ 0.05.Results:Treatment with ALA prevented the pregnancy-dependent SBP increase typical of the SHRSP model (SBP GD14 SHRSP: 169.3±2.1 mmHg vs. SHRSP+ALA: 146.1±3.4, p˂0.001). Furthermore, fetuses carried by ALA-treated SHRSP displayed increased weights (SHRSP: 1.75±0.05g vs. SHRSP+ALA: 1.99±0.01g, p˂0.05) and decreased cephalization indexes on GD20, indicating an improvement in the asymmetric growth restriction pattern. Treated dams also presented increased numbers of glycogen trophoblasts (PAS+cells) in the junctional zone and an enhanced vessel density on Isolectin B4+staining, suggesting an improved placental function.Conclusions:ALA administration during early pregnancy in the SHRSP model ameliorated maternal signs and improved placental function and fetal growth, emerging as a novel therapeutic intervention in pregnancies affected by chronic hypertension

Pregnancy is a unique event in which a fetus, despite being genetically and immunologically different from the mother (a hemi-allograft), develops in the uterus. Successful pregnancy implies avoidance of rejection by the maternal immune system. Fetal and maternal immune cells come into direct contact at the decidua, which is a highly specialized mucous membrane that plays a key role in fetal tolerance. Uterine dendritic cells (DC) within the decidua have been implicated in pregnancy maintenance. DC serve as antigen-presenting cells with the unique ability to induce primary immune responses. Just as lymphocytes comprise different subsets, DC subsets have been identified that differentially control lymphocyte function. DC may also act to induce immunologic tolerance and regulation of T cell-mediated immunity. Current understanding of DC immunobiology within the context of mammalian fetal-maternal tolerance is reviewed and discussed herein.

Disruption of fetal-maternal tolerance mechanisms can contribute to pregnancy complications, including spontaneous abortion. Galectin-9 (LGALS9), a tandem repeat lectin associated with immune modulation, is expressed in the endometrium during the mid and late secretory phases and in decidua during human early pregnancy. However, the role of LGALS9 during pregnancy remains poorly understood. We used real-time PCR and immunohistochemical staining to analyze the expression of Lgals9/LGALS9 during mouse gestation as well as in human tissues obtained from normal pregnancy and spontaneous abortions. In mice, three Lgals9splice variants were detected, the expression of which was differentially regulated during gestation. Furthermore, decidual Lgals9expression was deregulated in a mouse model of spontaneous abortion, whereas placental levels did not change. We further found that the LGALS9 D5 isoform suppresses interferon gamma production by decidual natural killer cells. In human patients, six Lgals9splice variants were detected, and a decrease in Lgals9D5/10was associated with spontaneous abortion. Altogether, these results show a differential regulation of Lgals9isoform expression during normal and pathological pregnancies and designate Lgals9as a potential marker for adverse pregnancy outcomes.

Mouse and human pregnancy-specific glycoproteins (PSG) are known to exert immunomodulatory functions during pregnancy by inducing maternal leukocytes to secrete anti-inflammatory cytokines that promote a tolerogenic decidual microenvironment. Many such anti-inflammatory mediators also function as proangiogenic factors, which, along with the reported association of murine PSG with the uterine vasculature, suggest that PSG may contribute to the vascular adaptations necessary for successful implantation and placental development. We observed that PSG22 is strongly expressed around the embryonic crypt on Gestation Day 5.5, indicating that trophoblast giant cells are the main source of PSG22 during the early stages of pregnancy. PSG22 treatment up-regulated the secretion of transforming growth factor beta 1 and vascular endothelial growth factor A (VEGFA) in murine macrophages, uterine dendritic cells, and natural killer cells. A possible role of PSGs in uteroplacental angiogenesis is further supported by the finding that incubation of endothelial cells with PSG22 resulted in the formation of tubes in the presence and absence of VEGFA. We determined that PSG22, like human PSG1 and murine PSG17 and PSG23, binds to the heparan sulfate chains in syndecans. Therefore, our findings indicate that despite the independent evolution and expansion of human and rodent PSG, members in both families have conserved functions that include their ability to induce anti-inflammatory cytokines and proangiogenic factors as well as to induce the formation of capillary structures by endothelial cells. In summary, our results indicate that PSG22, the most abundant PSG expressed during mouse early pregnancy, is likely a major contributor to the establishment of a successful pregnancy.