Marijke M. Faas

Maternal obesity increases the risk of obesity and metabolic disease in the offspring, yet the cellular mechanisms that program adipose tissue development remain poorly understood. Mesenchymal stem cells (MSCs), the precursors of adipocytes, may represent an early target of metabolic programming during fetal development. In this study, we investigated whether maternal obesity alters stemness, redox homeostasis and adipogenic signaling through FOXO1 in neonatal MSCs. MSCs were isolated from Wharton's jelly of umbilical cords from neonates born to mothers with normal weight (NW‐MSCs, n = 15) or obesity (OB‐MSCs, n = 15). OB‐MSCs exhibited reduced stemness characteristics, including lower OCT3/4 expression and decreased clonogenic capacity. These cells also displayed increased mitochondrial superoxide levels and reduced SOD2 expression, indicating mitochondrial oxidative stress. In addition, OB‐MSCs showed increased GSH levels and decreased antioxidant enzyme response, compared to NW‐MSCs. Further, OB‐MSCs exhibited higher FOXO1 expression levels, reduced acetyl‐FOXO1 levels, and altered subcellular localization during early adipogenesis, consistent with reduced repression of the adipogenic regulator PPARγ. Finally, OB‐MSC–derived adipocytes exhibited increased PPARγ expression at later stages of differentiation. These findings suggest that maternal obesity disrupts redox balance and FOXO1 dynamics in neonatal MSCs, thereby shifting early adipogenic signaling toward enhanced adipocyte commitment. This early programming mechanism may expand the adipocyte precursor pool, potentially predisposing the progeny to higher adiposity and metabolic disorders later in life.

Recent studies evidence an altered bioenergetic profile and higher adipogenic commitment in the mesenchymal stem cells (MSC) from neonates of mothers with obesity. We hypothesize that these alterations may also affect the secretome of these cells. The aim of this study was to characterize the secretome of MSCs from the offspring of women with obesity compared to the ones from normal-weight women, both before and during adipogenesis. Wharton’s jelly-derived MSCs were isolated from newborns of normal-weight women (NW-MSC; Body Mass Index 18.5-24.5 kg/m2) and women with obesity (OB-MSC; Body Mass Index > 30 kg/m2) and cultured for 0, 5, and 21 days of adipogenesis. The secretome from these cells was collected during the three timepoints and characterized by mass spectrometry. Our findings reveal fundamental differences in the secretome profiles, primarily associated with pathways involved in cellular and metabolic processes. Maternal obesity was found to decrease redox capacity at day 0 but subsequently triggered a compensatory increase in redox proteins during adipogenesis of OB-MSCs. Additionally, OB-MSCs secreted higher levels of lipid synthesis-related proteins and proinflammatory adipokines, which may contribute to the dysregulated adipogenesis observed in obesity. These preliminary data indicate that maternal obesity programs the secretome of neonatal MSCs, supporting the hypothesis that maternal obesity imprints early progenitor cells and potentially dictates the future metabolic status of the offspring’s adipocytes.

The maternal gut microbiome is involved in adapting immune responses to the presence of the semiallogeneic foetus. We have previously shown that antibiotics‐induced gut dysbiosis, alterations in the maternal immune response and decreased foetal and placental weight. Here, we tested whether Bifidobacterium animalis subsp. lactis BL‐99 (BL‐99) could improve antibiotics‐induced gut dysbiosis, maternal immune responses and foetal and placental weight. To do so, pregnant mice received antibiotics in their drinking water (day 9‐16) and BL‐99 via oral gavage (day 9‐18). After sacrifice (day 18) immune responses were measured using flowcytometry. BL‐99 increased placental weight in antibiotics‐treated pregnant mice. BL‐99 did not significantly change the maternal microbiome, but improved maternal immune responses by decreasing splenic Th1 cells and Treg cells, and increasing FoxP3/RoRγT double‐positive cells in the Peyer's patches to levels observed in control pregnant mice. BL‐99 also improved monocyte subsets and activation status. Additionally, BL‐99 changed foetal monocyte subsets and activational status and increased foetal splenic Th cells. We thus showed that the effect of antibiotics treatment on immune cells and placental weight was mitigated by supplementation of BL‐99. We suggest that pregnancy complications associated with a disturbed microbiome and immune responses, such as preeclampsia or obese pregnancies, could benefit from BL‐99 supplementation. This should be tested in future studies.

Maternal obesity is a risk factor for increased fetal adiposity. The underlying mechanisms remain unclear, however, emerging evidence suggests that mesenchymal stem cells (MSCs), which are the precursors of adipocytes, from neonates of mothers with obesity exhibit enhanced adipogenic differentiation potential. We hypothesise that the MSCs of neonates from mothers with obesity have different stemness potential and redox state compared to the MSCs from mothers with normal weight. MSCs were isolated from neonates of women with obesity (BMI>30 kg/m², OB-MSCs) and women with normal weight (BMI 2 ^•- ), together with lower antioxidant SOD2 gene expression, compared to NW-MSCs (p2 O ₂ (250 μM), OB-MSCs displayed attenuated antioxidant response, with lower SOD1, SOD2 and GPX1 gene expression as compared to NW-MSCs (p2 O ₂ , 400 μM), total ROS levels were lower in OB-MSCs than in NW-MSCs. In contrast, when challenged for mitochondrial ROS, OB-MSCs showed higher levels of mitochondrial superoxide production as compared to NW-MSCs (p2 ^•- and a different basal and oxidative stress-induced redox profile compared to NW-MSCs. These changes in OB-MSCs could predispose them to an increase adipogeneic commitment. GRAPHICAL

The development of the fetal immune response is a highly complex process. In the present review, we describe the development of the fetal immune response and the role of the maternal gut bacteria in this process. In contrast to the previous belief that the fetal immune response is inert, it is now thought that the fetal immune response is uniquely tolerant to maternal and allo-antigens, but able to respond to infectious agents, such as bacteria. This is accomplished by the development of T cells toward regulatory T cells rather than toward effector T cells, but also by the presence of functional innate immune cells, such as monocytes and NK cells. Moreover, in fetuses there is different programming of CD8 + T cells and memory T cells toward innate immune cells rather than to adaptive immune cells. The maternal gut bacteria are important in shaping the fetal immune response by producing bacterial products and metabolites that pass the placenta into the fetus and influence development of the fetal immune response. Insight into how and when these products affect the fetal immune response may open new treatment options with pre- or probiotics to affect the maternal gut bacteria and therewith the fetal immune response.

Maternal obesity during pregnancy is associated with adverse pregnancy outcomes. This might be due to undesired obesity-induced changes in the maternal gut microbiota and related changes in the maternal immune adaptations during pregnancy. The current study examines how obesity affects gut microbiota and immunity in pregnant obese and lean mice during mid-pregnancy (gestational day 12 (GD12)). C57BL/6 mice were fed a high-fat diet or low-fat diet from 8 weeks before mating and during pregnancy. At GD12, we analyzed the gut microbiota composition in the feces and immune responses in the intestine (Peyer’s patches, mesenteric lymph nodes) and the peripheral circulation (spleen and peripheral blood). Maternal obesity reduced beneficial bacteria (e.g., Bifidobacterium and Akkermansia) and changed intestinal and peripheral immune responses (e.g., dendritic cells, Th1/Th2/Th17/Treg axis, monocytes). Numerous correlations were found between obesity-associated bacterial genera and intestinal/peripheral immune anomalies. This study shows that maternal obesity impacts the abundance of specific bacterial gut genera as compared to lean mice and deranges maternal intestinal immune responses that subsequently change peripheral maternal immune responses in mid-pregnancy. Our findings underscore the opportunities for early intervention strategies targeting maternal obesity, ideally starting in the periconceptional period, to mitigate these obesity-related pregnancy effects.

Is periconceptional multiple-micronutrient supplement (MMS) use including folic acid (FA) compared to FA use only associated with increased embryonic growth, development, and birth weight in a high-risk population? Women with MMS intake show no significant differences in first-trimester morphological embryo development, but increased first-trimester embryonic growth trajectories and fewer neonates born small for gestational age (SGA), less than the 3rd percentile (β = 0.052, 95% CI 0.012–0.090, EV: β = 0.022, 95% CI 0.002–0.042) in women using MMS compared to those using only FA. Moreover, a 45% reduced risk of a neonate-born SGA (<p3) was shown in women using MMS compared to FA users (adjusted OR = 0.546, 95% CI 0.308, 0.969). Embryonic morphological development (Carnegie stages) and the occurrence of miscarriages did not differ between women using MMS or solely FA. Following the heterogeneity of the composition and dose of MMS preparations, it is unclear which specific micronutrient, combination, or dose explains the increased embryonic growth trajectory and reduction in risk for SGA. This also hampers the possibility of differentiating between the effects of FA alone or as a component of MMS. Our findings emphasize the importance of periconceptional maternal MMS use as a potential preventative intervention against reduced embryonic growth and neonates born SGA. Therefore, we recommend the periconceptional use of MMS in women at risk of inadequate micronutrient intake. However, awareness of potentially harmful side effects of high doses and combinations of micronutrients is essential, therefore the optimal composition and dose need to be investigated, and careful surveillance is recommended. This research was funded by the Department of Obstetrics and Gynaecology, Erasmus MC, University Medical Center, Rotterdam, The Netherlands, and the ZonMw grant Open Competition 2018 (09120011910046). The authors declare that they have no conflict of interest. NTR4356.

Purpose: Today’s diet consists of a substantial proportion of ultra-processed foods (UPF), especially in women with overweight and obesity in the reproductive period. High UPF intake results in an inadequate and unbalanced diet leading to derangements of several metabolic pathways detrimental to pregnancy and birth outcomes. Therefore, we aim to investigate whether UPF intake in the periconceptional period affects total homocysteine plasma levels (tHcy). Methods: 1532 participants were included from the prospective Rotterdam Periconceptional Cohort. UPF intake was calculated using Food Frequency Questionnaires including items classified as 4 in the Nova classification, and tHcy was measured by using liquid chromatography-tandem mass spectrometry system, with an interassay coefficient of variation of < 5.5%. Multivariable linear regression modeling was used and adjusted for covariates and significant interaction terms. Results: Women with overweight or obesity showed significantly higher percentage of UPF intake (respectively, 50.3 and 51.3%) and higher tHcy (respectively, 6.6 and 6.3 µmol/L, Kruskal–Wallis test; respectively, p < 0.001 and p = 0.04) compared to women with normal BMI (UPF intake: 46.8%, tHcy: 6.1 µmol/L). A 10% higher intake of UPF was associated with an increase in tHcy (adjusted: β = 1.31, 95% CI = 0.38–2.23). Analysis stratified for BMI classification showed comparable associations in normal weight participants (adjusted: β = 1.07, 95% CI = 0.06–2.07); however, no significant association in participants with overweight (adjusted: β = 0.06, 95% CI = − 0.95–1.07) and obesity (adjusted: β = 1.70, 95% CI = − 0.52–3.92) was shown. Conclusion: This study showed that a higher intake of UPF is associated with increased tHcy. Better knowledge and awareness of the nutritional quality of the diet in the periconceptional period may contribute to 1-CM and subsequently improve pregnancy course and outcome. Trial registration number and date: NTR4356, November 2010.

The gut microbiota are involved in adaptations of the maternal immune response to pregnancy. We therefore hypothesized that inducing gut dysbiosis during pregnancy alters the maternal immune response. Thus, pregnant mice received antibiotics from day 9 to day 16 to disturb the maternal gut microbiome. Feces were collected before, during and after antibiotic treatment, and microbiota were measured using 16S RNA sequencing. Mice were sacrificed at day 18 of pregnancy and intestinal (Peyer’s patches (PP) and mesenteric lymph nodes (MLN)) and peripheral immune responses (blood and spleen) were measured using flow cytometry. Antibiotic treatment decreased fetal and placental weight. The bacterial count and the Shannon index were significantly decreased (Friedman, followed by Dunn’s test, p < 0.05) and the bacterial genera abundance was significantly changed (Permanova, p < 0.05) following antibiotics treatment as compared with before treatment. Splenic Th1 cells and activated blood monocytes were increased, while Th2, Th17 and FoxP3/RoRgT double-positive cells in the PP and MLNs were decreased in pregnant antibiotics-treated mice as compared with untreated pregnant mice. In addition, intestinal dendritic cell subsets were affected by antibiotics. Correlation of immune cells with bacterial genera showed various correlations between immune cells in the PP, MLN and peripheral circulation (blood and spleen). We conclude the disturbed gut microbiota after antibiotics treatment disturbed the maternal immune response. This disturbed maternal immune response may affect fetal and placental weight.

Uterine natural killer (uNK) cells, a specific type of natural killer (NK) cells, are important cells at the foeto-maternal interface in humans as well as in mice. uNK cells are part of the innate lymphoid cells group 1. Especially in the mouse, but also in the rat, many in vivo studies have been performed to evaluate the role of uNK cells in placental development. These studies have shown that uNK cells are not indispensable to pregnancy, but that they play an important role in optimal decidual angiogenesis in early pregnancy, trophoblast invasion and spiral artery remodelling in the mouse placenta. Based on the mouse studies, various in vitro studies, as well as immunohistological studies of the human placenta from elective abortions, have shown that uNK cells have similar functions in the human placenta. In the present narrative review, the role of the uNK cells in the development of the mouse and rat placenta will be discussed first. Thereafter, studies on the role of human uNK cells in the human placenta will be reviewed and these studies will be discussed in the light of the knowledge on mouse uNK cells.