Iron Metabolism in Normal and Pathological Pregnancies and Fetal Consequences

Arsenic induces ferroptosis in HTR-8/SVneo cells and placental damage

Placenta ferroptosis has been proven to be associated with a variety of adverse pregnancy outcomes. Arsenic, a conventional metal noxious substance, has garnered considerable attention due to traversing the placental barrier. How arsenic induces placental ferroptosis and reproductive developmental toxicities remains largely unknown. Herein, we investigated the impact of sodium arsenite (As (III)) on iron homeostasis in the placenta through both in vivo and in vitro experiments by using HTR-8/SVneo cells and ICR pregnant mice. As (III) up-regulated the expression of genes or proteins associated with iron uptake (TFRC, DMT1), iron storage (FTH, FTL), ferritin autophagy (NCOA4), and heme degradation (HO-1), and induced cell iron overload. Additionally, accumulation of the lipid hydroperoxide malondialdehyde within cells was triggered by As (III) through inhibition of the Nrf2/GPX4 signal pathway, which resulted in cellular ferroptosis. Fer-1 effectively alleviated the suppression of GPX4 induced by As (III), reduced the accumulation of intracellular lipid peroxidation product MDA, and mitigated cellular ferroptosis. As (III) affected the iron homeostasis, as evidenced by the abnormal iron accumulation in the placenta. Placental structural abnormalities and hemorrhage may be the reason for As (III) causing placental injury and subsequent poor pregnancy outcomes. This study provides new insights into understanding the mechanisms by which As (III) produces placental damage and possible fetal developmental toxicity.

Association between Adiposity and Iron Status in Women of Reproductive Age: Data from the UK National Diet and Nutrition Survey (NDNS) 2008-2019

BACKGROUND

Overweight/obesity and iron deficiency (ID) are highly prevalent in women of reproductive age (WRA), impacting on women's health. Obesity is a risk factor for nutritional deficiencies but its association with ID is unclear.

OBJECTIVES

To determine the association between adiposity and markers of iron status and ID prevalence in WRA.

METHODS

This cross-sectional study analyzed the National Diet and Nutrition Survey (2008-2019) data, focusing on women aged 18-49 y with body mass index (BMI) ≥18.5 kg/m2. Prevalence of anemia, iron deficiency anemia (IDA), and ID were analyzed. Ferritin was adjusted for C-reactive protein. Iron status was assessed across high and low BMI, waist circumference (WC), waist-to-height ratio (WHtR), and waist-to-hip ratio (WHR). χ2, linear and logistic regressions were performed adjusting for covariates.

RESULTS

Among 1098 WRA, 496 normal weight and 602 overweight/obesity, prevalence rates were: anemia 9.2% and IDA 6.8%. Anemia was more prevalent in those with higher WHtR and WHR (11.9% compared with 5.9% and 16.7% compared with 6.5%, both P < 0.001). WRA with increased WC, WHtR, and WHR had higher IDA prevalence than those with lower adiposity (8.5% compared with 4.3%, P = 0.005; 9.4% compared with 3.3%, P < 0.001; 12.1% compared with 4.9%, P < 0.001). ID prevalence was 49.7% (ferritin cutoff 30 μg/L) and 19.6% (ferritin cutoff 15 μg/L), showing similar rates across adiposity groups. ID prevalence defined by soluble transferrin receptor (sTfR) was higher in women with increased WHR (P = 0.001). Higher WHR predicted ID categorized by sTfR (adjusted odds ratio [aOR]: 2.104, P = 0.004), and WHtR and WHR predicted anemia and IDA (anemia: WHtR aOR: 2.006, P = 0.036; WHR aOR: 4.489, P < 0.001 and IDA: WHtR aOR: 2.942, P = 0.012; WHR aOR: 4.142, P < 0.001).

CONCLUSIONS

At least 1 in 5 WRA in the UK are iron deficient, highlighting the need to revise current policies. Greater central adiposity was strongly associated with impaired iron status and the development of anemia, IDA, and ID.

Physiologically based trimester-specific serum ferritin thresholds for iron deficiency in US pregnant women

ABSTRACT

Serum ferritin (SF) concentration is the most widely used indicator for iron deficiency (ID). During pregnancy, the World Health Organization recently recommended SF thresholds for ID of <15 μg/L for the first trimester of pregnancy, based on expert opinion, and made no recommendations for the second and third trimesters. We examined the relationship of SF with 2 independent indicators of the onset of iron-deficient erythropoiesis, hemoglobin and soluble transferrin receptor 1, in cross-sectional data from US National Health and Nutrition Examination Survey for 1999 to 2010 and 2015 to 2018. We included 1288 pregnant women aged 15 to 49 years and excluded women with inflammation or potential liver disease. We used restricted cubic spline (RCS) regression analysis to determine SF thresholds for iron-deficient erythropoiesis. SF decreased during pregnancy; geometric mean SF was higher during the first and lower during the second and third trimesters. Using RCS analysis, the SF thresholds identified during pregnancy were <25.8 μg/L (18.1-28.5) during first trimester, <18.3 μg/L (16.3-22.9) during second trimester, and <19.0 μg/L (14.4- 26.1) during third trimester. These SF threshold levels track concentrations of hepcidin, the iron-regulatory hormone controlling the mobilization of iron stores. An SF concentration of <15 μg/L as the criterion for ID may underestimate the true prevalence of ID throughout pregnancy. In our study, an additional 1 of every 10 pregnant women would be recognized as iron deficient by using the physiologically based thresholds at SF of ∼25 μg/L during the first and ∼20 μg/L during the second and third trimesters.

Effects of Maternal Dietary Enteromorpha prolifera Polysaccharide Iron Supplement on Mineral Elements and Iron Level of Neonatal Piglets

Iron plays a key role in maternal health during pregnancy and fetal growth. Enteromorpha polysaccharide-iron (EP-Fe) as an organic iron chelate may improve the iron transmission of mother and offspring, ameliorate the poor pregnancy outcomes of sows, and alleviate the growth restriction of piglets caused by iron deficiency. This study aimed to evaluate the effects of maternal dietary supplementation with EP-Fe on reproductive performance and placental iron transmission of sows, as well as growth performance of piglets. Sixty pregnant sows at the 95th day of gestation were randomly divided into control group and EP-Fe group (EP-Fe, 139 mg kg-1). Blood samples of sows and neonatal piglets, colostrum, and tissue samples were collected on the day of delivery. The animal experiment ended at the 21st day of post-delivery. Results showed that maternal dietary EP-Fe increased colostrum iron (P < 0.05) of sows, as well as final litter weight (P < 0.05) and average daily weight of piglets (P < 0.05) during days 1-21 of lactation, as well as iron and manganese content in umbilical cord blood (P < 0.05) and hepatic iron of neonatal piglets (P < 0.01), and decreased fecal iron (P < 0.001), serum calcium (P < 0.05), phosphorus (P < 0.05), and zinc (P < 0.01) in the parturient sow. RT-qPCR results showed that Fpn1 and Zip14 in placenta, as well as TfR1 and Zip14 in duodenum of neonatal piglets, were activated by maternal EP-Fe supplement. These findings suggest that maternal dietary EP-Fe could increase iron storage of neonatal piglets via improving placental iron transport and iron secretion in colostrum, thus enhancing the growth performance of sucking piglets.

Oxidative Stress, Lipid Peroxidation and Ferroptosis Are Major Pathophysiological Signatures in the Placental Tissue of Women with Late-Onset Preeclampsia

Preeclampsia, a serious and potentially life-threatening medical complication occurring during pregnancy, is characterized by hypertension and often accompanied by proteinuria and multiorgan dysfunction. It is classified into two subtypes based on the timing of diagnosis: early-onset (EO-PE) and late-onset preeclampsia (LO-PE). Despite being less severe and exhibiting distinct pathophysiological characteristics, LO-PE is more prevalent than EO-PE, although both conditions have a significant impact on placental health. Previous research indicates that different pathophysiological events within the placenta may contribute to the development of preeclampsia across multiple pathways. In our experimental study, we investigated markers of oxidative stress, ferroptosis, and lipid peroxidation pathways in placental tissue samples obtained from women with LO-PE (n = 68) compared to healthy control pregnant women (HC, n = 43). Through a comprehensive analysis, we observed an upregulation of specific molecules associated with these pathways, including NADPH oxidase 1 (NOX-1), NADPH oxidase 2 (NOX-2), transferrin receptor protein 1 (TFRC), arachidonate 5-lipoxygenase (ALOX-5), acyl-CoA synthetase long-chain family member 4 (ACSL-4), glutathione peroxidase 4 (GPX4) and malondialdehyde (MDA) in women with LO-PE. Furthermore, increased ferric tissue deposition (Fe3+) was observed in placenta samples stained with Perls' Prussian blue. The assessment involved gene and protein expression analyses conducted through RT-qPCR experiments and immunohistochemistry assays. Our findings underscore the heightened activation of inflammatory pathways in LO-PE compared to HC, highlighting the pathological mechanisms underlying this pregnancy disorder.

Relationship between prepregnancy BMI and the concentrations of iron, calcium, and magnesium in serum and hair during the first trimester of pregnancy in women

BACKGROUND

In women of childbearing age, a low dietary supply of iron, calcium, and magnesium is often observed. Minerals deficiency in pregnant women is often associated with abnormal body weight and may impact fetal development disorders. The aim of this study is to determine the relationship between prepregnancy body mass index (BMI) and the dietary intake of iron, calcium and magnesium and their concentrations in serum and hair in pregnant women.

METHOD

The study involved 97 Caucasian/white low-risk pregnant women at 12 weeks of gestation. The analysis of minerals in serum and hair samples was performed using atomic absorption spectrometry. Pre-pregnancy BMI was calculated based on self-reported weight. The study used a validated questionnaire and a 24-h recall nutrition interview, which were analyzed using Aliant software.

RESULTS

It was found that overweight and obese women exhibited higher magnesium concentration in serum, while iron content in serum and hair was markedly lower compared to women with normal body weight. The average total supply of iron was below the recommendation in pregnant women. Moreover, an inverse significant relationship was observed between BMI and iron concentration in hair and serum in the whole population.

CONCLUSION

In conclusion, being overweight or obese before pregnancy is associated with low dietary iron intake and low iron concentration in serum and hair during the first trimester of pregnancy in women.

Unraveling the Role of Maternal Serum Ferritin Levels in Preterm Delivery: A Comprehensive Review

Preterm delivery remains a critical global health concern, with numerous adverse consequences for both neonate and healthcare systems. Understanding the relationship between maternal ferritin levels, as a marker of iron status, and the risk of preterm birth is the focal point of this comprehensive review. We provide insights into the multifaceted nature of this connection, highlighting factors that influence maternal ferritin levels, including dietary intake, genetic and physiological variations, comorbidities, and iron supplementation. While evidence suggests an association between low maternal ferritin levels and preterm birth, causality remains elusive, necessitating further research with robust study designs. The potential mechanisms linking maternal iron status to preterm birth, such as inflammation, infection, and oxidative stress, are explored, underscoring the need for in-depth investigations. This comprehensive review emphasizes the clinical importance of assessing and monitoring maternal ferritin levels in prenatal care and advocates for public health initiatives to raise awareness and provide targeted interventions, particularly in high-risk populations. As we strive to address these unanswered questions and embark on innovative research directions, the aim is to ultimately enhance our understanding of the complex relationship between maternal iron status and preterm birth, leading to improved maternal and child health outcomes.

Molecular insights into placental iron transfer mechanisms and maternofetal regulation

PURPOSE

Adequate iron transportation from the mother across the placenta is crucial for fetal growth and establishing sufficient iron stores in neonates at birth. The past decade has marked significant discoveries in iron metabolism with the identification of new players and mechanisms. Immunohistochemical studies rendered valuable data on the localization of substantial iron transporters on placental syncytiotrophoblasts. However, the function and regulation of maternal-placentofetal iron transporters and iron handling is still elusive and requires more attention.

METHODS

A thorough literature review was conducted to gather information about placental iron transfer, the role of regulators and maintenance of iron homeostasis.

RESULTS

The role of classical and new players in maternal-fetal iron transport and the regulation in the placenta has been addressed in this review. Animal and human studies have been discussed. The role of placental iron regulation in thalassemia and hemochromatosis pregnancies has been reviewed.

CONCLUSIONS

The current advances that highlight the mechanisms of placental iron regulation and transport in response to maternal and fetal signals have been presented.

Iron metabolism and ferroptosis: A pathway for understanding preeclampsia

Preeclampsia (PE) is a serious medical condition that poses a significant health risk to women and children worldwide, particularly in the middle- and low-income countries. It is a complex syndrome that occurs as a result of abnormal pregnancy. Hypertension is the most common symptom of PE, with proteinuria and specific organ systems as detrimental targets. PE's pathogenesis is diverse, and its symptoms can overlap with other diseases. In early pregnancy, when the placenta takes over control, oxidative stress may be closely associated with ferroptosis, a type of cell death caused by intracellular iron accumulation. Ferroptosis in the placenta is defined by redox-active iron availability, loss of antioxidant capacity and phospholipids containing polyunsaturated fatty acids (PUFA) oxidation. Recent studies suggest a compelling potential link between ferroptosis and PE. In this article, we comprehensively review the current understanding of PE and discuss one of its emerging underlying mechanisms, the ferroptosis pathway. We also provide perspective and analysis on the implications of this process in the diagnosis, prevention, and treatment of preeclampsia. We aim to bridge the gap between clinicians and basic scientists in understanding this harmful disease and challenge the research community to put more effort into this exciting new area.

The Ferritin, Hepcidin and Cytokines Link in the Diagnoses of Iron Deficiency Anaemia during Pregnancy: A Review

Following a diagnosis of iron deficiency anaemia in pregnancy, iron supplements are prescribed using UK guidelines; however, despite this, the condition remains highly prevalent, affecting up to 30% of pregnant women in the UK. According to the World Health Organisation, it globally accounts for 45% in the most vulnerable groups of pregnant women and infants (<5 years old). Recently, the efficacy of iron replacement therapy and the effectiveness of current standard testing of iron parameters have been reviewed in order to evaluate whether a more accurate diagnosis can be made using alternative and/or supplementary markers. Furthermore, many questions remain about the mechanisms involved in iron metabolism during pregnancy. The most recent studies have shed more light on serum hepcidin and raised questions on the significance of pregnancy related inflammatory markers including cytokines in iron deficiency anaemia. However, research into this is still scarce, and this review aims to contribute to further understanding and elucidating these areas.

Effect of Adherence to the Mediterranean Diet on Maternal Iron Related Biochemical Parameters during Pregnancy and Gestational Weight Gain

Gestation is a crucial life stage for both women and offspring, and outcomes are affected by many environmental factors, including diet. The Mediterranean dietary pattern (MD) is considered a healthy eating pattern that can provide the nutritional requirements of pregnancy. Meanwhile, iron deficiency anemia is one of the most frequent complications related to pregnancy. This study aimed to evaluate how the level of adherence to the MD influences maternal gestational weight gain and specific iron-related maternal biochemical parameters during the pregnancy. Accordingly, an observational, population-based study using data from pregnant women conducted over the entire course of their pregnancy was carried out. Adherence to the MD was assessed once using the MEDAS score questionnaire. Of the 506 women studied, 116 (22.9%) were classified as demonstrating a high adherence, 277 (54.7%) a medium adherence, and 113 (22.3%) a low adherence to the MD. No differences were observed in gestational weight gain among the MD adherence groups but the adequacy of weight gain did vary among the groups, with the proportions of inadequate (insufficient or excessive) weight gain presenting the most notable differences. Total anemia prevalence was 5.3%, 15.6%, and 12.3%, respectively, during the first, second, and third trimesters. For iron-related biochemical parameters, no differences are observed among the adherence groups during pregnancy. With high adherence to the MD as the reference group, the crude odds of iron deficiency diagnosis are significant in the first trimester for both the medium [OR = 2.99 (1.55-5.75)] and low [OR = 4.39 (2.15-8.96)] adherence groups, with deficient adherence to the Mediterranean dietary pattern being responsible for 66.5% (35.5-82.6) and 77.2% (53.5-88.8) of the risk of iron deficiency diagnosis for medium and low adherence, respectively. However, adjusted odds ratios were not significant, possibly due to the small sample size. Our data suggest that MD adherence could be related to gestational weight gain adequacy and that optimal adherence could reduce iron deficiency and/or anemia during pregnancy in the studied population.

Hypophosphataemia risk associated with ferric carboxymaltose in heart failure: A pooled analysis of clinical trials

AIMS

Iron deficiency is a common finding among patients with heart failure (HF) and is associated with adverse outcomes, including decreased quality of life, increased risk of hospitalization, and decreased survival. Intravenous ferric carboxymaltose (FCM) has been shown to improve outcomes among patients with HF and concomitant iron deficiency, but FCM is associated with an increased risk of hypophosphataemia. We aimed to better characterize this risk among HF populations.

METHODS AND RESULTS

This pooled analysis examined data from 41 studies of adults with iron deficiency across disease states and therapeutic areas. Among the 7931 patients treated with FCM available for analysis, 14% made up the HF subgroup. Additional subgroups included women's health (36%), non-dialysis-dependent chronic kidney disease (NDD-CKD; 27%), haemodialysis-dependent chronic kidney disease (HD-CKD; 1%), gastrointestinal (10%), neurology (3%), and other (10%). The incidence of post-baseline moderate or severe hypophosphataemia (i.e. serum phosphate [PO4 3- ] level <2.0 mg/dL) varied across the therapeutic areas, with the lowest incidences observed in the HD-CKD (0%), HF (8.1%), and NDD-CKD (12.8%) subgroups. The prevalence of moderate or severe hypophosphataemia among the women's health, other, gastrointestinal, and neurology subgroups was 30.1%, 40.6%, 51.0%, and 55.6%, respectively. In the HF subgroup, one patient (<0.1%) had a serum PO4 3- of <1.0 mg/dL recorded, compared with 4.8% and 4.0% of the subjects in the neurology and gastrointestinal groups, respectively. With the exception of the HD-CKD subgroup, mean serum PO4 3- levels decreased through weeks 2 to 4, and then returned toward baseline and plateaued by week 8. The strongest predictor of hypophosphataemia was preserved kidney function (estimated glomerular filtration rate: >60 mL/min/1.73 m2 vs. <30 mL/min/1.73 m2 ; odds ratio: 12.2). Among patients in the HF subgroup, the incidence of treatment-emergent adverse events potentially related to hypophosphataemia (e.g. cardiac failure, ventricular tachyarrhythmias, fatigue, muscle weakness, bone pain, neurological symptoms, and muscle pain) was lower among FCM-treated patients than among those receiving placebo, and lower among patients with a post-baseline PO4 3- <2 mg/dL vs. those not meeting such criteria.

CONCLUSIONS

The risk of laboratory-assessed hypophosphataemia in HF patients treated with FCM was lower than that seen in patients in other therapeutic areas treated with FCM, and clinical events associated with hypophosphataemia are uncommon with FCM therapy in this population. Appropriate monitoring, particularly soon after administration in the unlikely event of repeated dosing in HF patients, will allow for further refinement of management strategies. [Correction added on 24 February 2023, after first online publication: In the preceding sentence, "…administration, will allow…" has been corrected to "…administration in the unlikely event of repeated dosing in HF patients, will allow…" in this version.].

The Placentas of Women Who Suffer an Episode of Psychosis during Pregnancy Have Increased Lipid Peroxidation with Evidence of Ferroptosis

Psychosis is a complex entity characterized by psychological, behavioral, and motor alterations resulting in a loss of contact with reality. Although it is not common, pregnancy can be a period in which a first episode of psychosis can manifest, entailing detrimental consequences for both the fetus and the mother. The pathophysiological basis and study of maternofetal wellbeing need to be further elucidated. Lipid peroxidation and ferroptosis are two phenomena that are tightly linked to the placental dysfunction commonly observed in different complications of pregnancy. In the present study, we aim to explore the histopathological and gene expression of different markers of lipid peroxidation and ferroptosis in the placentas of women who underwent a first episode of psychosis during their pregnancy (n = 22). The aim is to then compare them with healthy pregnant women (n = 20). In order to achieve this goal, iron deposits were studied using Prussian Blue staining. In addition, the protein/gene expression of a transferrin receptor (TFRC), as well as an acyl-CoA synthetase long-chain family member 4 (ACSL-4), arachidonate lipoxygenase-5 (ALOX-5), malondialdehyde (MDA), and glutathione peroxidase 4 (GPX4) were all analyzed through gene expression (RT-qPCR) and immunohistochemical procedures. Our results demonstrate an increased presence of iron deposits that are accompanied by a further expression of TFRC, ACSL-4, ALOX-5, MDA, and GPX4-all of which are observed in the placenta tissue of women who have suffered from a first episode of psychosis. Therefore, in our study, a histopathological increase in lipid peroxidation and ferroptosis markers in the affected women is suggested. However, further studies are needed in order to validate our results and to establish possible consequences for the reported alterations.

Maternal heme-enriched diet promotes a gut pro-oxidative status associated with microbiota alteration, gut leakiness and glucose intolerance in mice offspring

Maternal environment, including nutrition and microbiota, plays a critical role in determining offspring's risk of chronic diseases such as diabetes later in life. Heme iron requirement is amplified during pregnancy and lactation, while excessive dietary heme iron intake, compared to non-heme iron, has shown to trigger acute oxidative stress in the gut resulting from reactive aldehyde formation in conjunction with microbiota reshape. Given the immaturity of the antioxidant defense system in early life, we investigated the extent to which a maternal diet enriched with heme iron may have a lasting impact on gut homeostasis and glucose metabolism in 60-day-old C3H/HeN mice offspring.

As hypothesized, the form of iron added to the maternal diet differentially governed the offspring's microbiota establishment despite identical fecal iron status in the offspring. Importantly, despite female offspring was unaffected, oxidative stress markers were however higher in the gut of male offspring from heme enriched-fed mothers, and were accompanied by increases in fecal lipocalin-2, intestinal para-cellular permeability and TNF-α expression. In addition, male mice displayed blood glucose intolerance resulting from impaired insulin secretion following oral glucose challenge. Using an integrated approach including an aldehydomic analysis, this male-specific phenotype was further characterized and revealed close covariations between unidentified putative reactive aldehydes and bacterial communities belonging to Bacteroidales and Lachnospirales orders.

Our work highlights how the form of dietary iron in the maternal diet can dictate the oxidative status in gut offspring in a sex-dependent manner, and how a gut microbiota-driven oxidative challenge in early life can be associated with gut barrier defects and glucose metabolism disorders that may be predictive of diabetes development.

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Maternal heminic vs. non-heminic iron intake differentially and persistently imprints the offspring's fecal microbiota.

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Males from heme-fed dams exhibit increased gut lumen reactive aldehydes in absence of direct dietary exposure to heme iron.

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Some of the increased reactive aldehydes closely covariated with Orders belonging to Bacteroidales and Lachnospirales.

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Maternal exposure to dietary heme iron impairs gut barrier and glucose tolerance in male offspring.