Impact of Obesity and Hyperglycemia on Placental Mitochondria

Pregnancy Disorders: A Potential Role for Mitochondrial Altered Homeostasis

Pregnancy is a complex and challenging process associated with physiological changes whose objective is to adapt the maternal organism to the increasing energetic requirements due to embryo and fetal development. A failed adaptation to these demands may lead to pregnancy complications that threaten the health of both mothers and their offspring. Since mitochondria are the main organelle responsible for energy generation in the form of ATP, the adequate state of these organelles seems crucial for proper pregnancy development and healthy pregnancy outcomes. The homeostasis of these organelles depends on several aspects, including their content, biogenesis, energy production, oxidative stress, dynamics, and signaling functions, such as apoptosis, which can be modified in relation to diseases during pregnancy. The etiology of pregnancy disorders like preeclampsia, fetal growth restriction, and gestational diabetes mellitus is not yet well understood. Nevertheless, insufficient placental perfusion and oxygen transfer are characteristic of many of them, being associated with alterations in the previously cited different aspects of mitochondrial homeostasis. Therefore, and due to the capacity of these multifactorial organelles to respond to physiological and pathophysiological stimuli, it is of great importance to gather the currently available scientific information regarding the relationship between main pregnancy complications and mitochondrial alterations. According to this, the present review is intended to show clear insight into the possible implications of mitochondria in these disorders, thus providing relevant information for further investigation in relation to the investigation and management of pregnancy diseases.

Placental mitochondrial impairment and its association with maternal metabolic dysfunction

The placenta plays an essential role in pregnancy, leading to proper fetal development and growth. As an organ with multiple physiological functions for both mother and fetus, it is a highly energetic and metabolically demanding tissue. Mitochondrial physiology plays a crucial role in the metabolism of this organ and thus any alteration leading to mitochondrial dysfunction has a severe outcome in the development of the fetus. Pregnancy-related pathological states with a mitochondrial dysfunction outcome include preeclampsia and gestational diabetes mellitus. In this review, we address the role of mitochondrial morphology, metabolism and physiology of the placenta during pregnancy, highlighting the roles of the cytotrophoblast and syncytiotrophoblast. We also describe the relationship between preeclampsia, gestational diabetes, gestational diabesity and pre-pregnancy maternal obesity with mitochondrial dysfunction.

Intrauterine hyperglycemia induces SIRT3-mediated mitochondrial dysfunction: the fetal origin pathogenesis of precocious osteoarthritis

OBJECTIVE

Diabetes and other metabolic and inflammatory comorbidities are highly associated with osteoarthritis (OA). However, whether early-life hyperglycemia exposure affects susceptibility to long-term OA is still unknown. The purpose of this study was to explore the fetal origins of OA and provide insights into early-life safeguarding for individual health.

METHOD

This study utilized streptozotocin to induce intrauterine hyperglycemia and performed destabilization of the medial meniscus surgery on the knee joints of the offspring mice to induce accelerated OA. Cartilage degeneration-related markers, as well as the expression levels of mitochondrial respiratory chain complexes and mitophagy genes in the adult offspring mice, were investigated. In vitro, mitochondrial function and mitophagy of chondrocyte C28/I2 cells stimulated under high glucose conditions were also evaluated. The methylation levels of the sirt3 gene promoter region in the articular cartilage of intrauterine hyperglycemia-exposed offspring mice were further analyzed.

RESULTS

In this study, we found that the intrauterine hyperglycemic environment could lead to an increase in individual susceptibility to OA in late adulthood, mainly due to persistently low levels of Sirt3 expression. Downregulation of Sirt3 causes impaired mitophagy in chondrocytes and abnormal mitochondrial respiratory function due to a failure to clear aged and damaged mitochondria in a timely manner. Overexpressing Sirt3 at the cellular level or using Sirt3 agonists like Honokiol in mouse models can partially rescue mitophagy disorders caused by the hyperglycemic environment and thus alleviate the progression of OA.

CONCLUSION

Our study revealed a significantly increased susceptibility to OA in the gestational diabetes mellitus offspring, which is partly attributed to exposure to adverse factors in utero and ultimately to the onset of disease via epigenetic modulation.

Maternal obesity: A potential disruptor of female fertility and current interventions to reduce associated risks

Currently, obesity has achieved epidemic levels in reproductive-aged women with a myriad of consequences. Obesity is susceptible to several reproductive complications that eventually affect fertility rates. These complications originate from the deteriorated quality of oocytes from mothers with obesity, which increases the probability of chromosomal aneuploidy, elevated reactive oxygen species production, compromised embryonic developmental competency, and eventually reduced fertility. Maternal obesity is linked to pregnancy complications such as implantation error, abortion, miscarriage, and early pregnancy loss. This review highlights the adverse effects of maternal obesity on female fertility, with a focus on the mechanistic link between maternal obesity and oocyte quality and discusses possible measures to reduce its associated risks.

Maternal obesity and offspring health: Adapting metabolic changes through autophagy and mitophagy

Maternal obesity leads to obstetric complications and a high prevalence of metabolic anomalies in the offspring. Among various contributing factors for maternal obesity-evoked health sequelae, developmental programming is considered as one of the leading culprit factors for maternal obesity-associated chronic comorbidities. Although a unified theory is still lacking to systematically address multiple unfavorable postnatal health sequelae, a cadre of etiological machineries have been put forward, including lipotoxicity, inflammation, oxidative stress, autophagy/mitophagy defect, and cell death. Hereinto, autophagy and mitophagy play an essential housekeeping role in the clearance of long-lived, damaged, and unnecessary cell components to maintain and restore cellular homeostasis. Defective autophagy/mitophagy has been reported in maternal obesity and negatively impacts fetal development and postnatal health. This review will provide an update on metabolic disorders in fetal development and postnatal health issues evoked by maternal obesity and/or intrauterine overnutrition and discuss the possible contribution of autophagy/mitophagy in metabolic diseases. Moreover, relevant mechanisms and potential therapeutic strategies will be discussed in an effort to target autophagy/mitophagy and metabolic disturbances in maternal obesity.

Cryopreserved placental biopsies maintain mitochondrial activity for high-resolution respirometry

BACKGROUND

High-resolution respirometry (HRR) of human biopsies can provide useful metabolic, diagnostic, and mechanistic insights for clinical research and comparative medical studies. Fresh tissues analysis offers the potential best condition, the drawback being the need to use them shortly after dissection for mitochondrial respiratory experiments. The development of effective long-term storage protocols for biopsies that allow the assessment of key Electron Transport System (ETS) parameters at later stages is thus a major need.

METHODS

We optimised a cryopreservation protocol that preserves mitochondrial membranes intactness, otherwise affected by direct tissue freezing. The protocol is based on a gradual freezing step from on-ice to liquid nitrogen and - 80 °C storage using a specific DMSO-based buffer.

RESULTS

Placenta is a suitable tissue to design and test the effectiveness of long-term storage protocols being metabolically active foetal tissue with mitochondrial dysfunctions contributing to placental disease and gestational disorders. Here we designed and tested the effectiveness of the cryopreservation protocol using human placenta biopsies; we measured the ETS activity by HRR of placenta specimens comparing fresh, cryopreserved, and snap frozen conditions.

CONCLUSIONS

By this protocol, Oxygen Consumption Rate (OCR) measurements of fresh and cryopreserved placental specimens are comparable whereas snap frozen procedure impairs mitochondrial activity.

Platelets and endothelial dysfunction in gestational diabetes mellitus

The prevalence of gestational diabetes mellitus (GDM) has increased in recent years, along with the higher prevalence of obesity in women of reproductive age. GDM is a pathology associated with vascular dysfunction in the fetoplacental unit. GDM-associated endothelial dysfunction alters the transfer of nutrients to the foetus affecting newborns and pregnant women. Various mechanisms for this vascular dysfunction have been proposed, of which the most studied are metabolic alterations of the vascular endothelium. However, different cell types are involved in GDM-associated endothelial dysfunction, including platelets. Platelets are small, enucleated cell fragments that actively take part in blood haemostasis and thrombus formation. Thus, they play crucial roles in pathologies coursing with endothelial dysfunction, such as atherosclerosis, cardiovascular diseases, and diabetes mellitus. Nevertheless, platelet function in GDM is understudied. Several reports show a potential relationship between platelet volume and mass with GDM; however, platelet roles and signaling mechanisms in GDM-associated endothelial dysfunction are unclear. This review summarizes the reported findings and proposes a link among altered amount, volume, mass, reactivity, and function of platelets and placenta development, resulting in fetoplacental vascular dysfunction in GDM.

Role of Inflammaging on the Reproductive Function and Pregnancy

During female lifetime and pregnancy, inflammation and cellular senescence are implicated in physiological processes, from ovulation and menstruation, to placental homeostasis and delivery. Several lifestyles, nutritional, and environmental insults, as well as long-lasting pregestational inflammatory diseases may lead to detrimental effects in promoting and sustaining a chronic excessive inflammatory response and inflammaging, which finally contribute to the decay of fertility and pregnancy outcome, with a negative effect on placental function, fetal development, and future health risk profile in the offspring. Maladaptation to pregnancy and obstetric disease may in turn increase maternal inflammaging in a feedback loop, speeding up aging processes and outbreak of chronic diseases. Maternal inflammaging may also impact, through transgenerational effects, on future adult health. Hence, efficacious interventions should be implemented by physicians and healthcare professionals involved in prevention activities to reduce the modifiable factors contributing to the inflammaging process in order to improve public health.

The role of chemerin in the regulation of cGAS-STING pathway in gestational diabetes mellitus placenta

Recent studies already confirmed that placenta mitochondrial dysfunction is associated with the progression of gestational diabetes mellitus (GDM). Besides, a possible relationship between adipokine chemerin and disulfide-bond A oxidoreductase-like protein (DsbA-L) had been revealed, whereas the potential interaction remains unclear. In addition, very little is still known about the cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) signaling pathway and its mechanisms of action in the context of GDM. The present study aims to investigate the underlying mechanism of cGAS-STING pathway and its regulatory relationship with chemerin in GDM. A total of 50 participants, including 25 cases of GDM patients and 25 pregnant women with normal glucose tolerance, were enrolled, and their placenta tissues at term labor were collected. Besides, an insulin resistance cell model was established on the human trophoblastic cell line to explore the molecular mechanism of chemerin on cGAS-STING pathway. Results showed that there were mitochondrial pathological changes in GDM placenta, accompanied by the decreased expression of DsbA-L, increased level of chemerin, and the activation of cGAS-STING pathway. In the insulin resistant cell model, overexpression of chemerin upregulated protein expression of DsbA-L, and recombinant chemerin presented time-dependent inhibition on the cGAS-STING pathway, but this effect was not dependent on DsbA-L. In conclusion, elevated chemerin is probably a protective mechanism, which may be a potential therapeutic strategy for GDM.

Placental F4-Neuroprostanes and F2-Isoprostanes are altered in gestational diabetes mellitus and maternal obesity

We investigated whether gestational diabetes mellitus (GDM) associated with maternal obesity modifies the placental profile of F₄-Neuroprostanes and F₂-Isoprostanes, metabolites of non-enzymatic oxidation of docosahexaenoic acid (DHA) and arachidonic acid (AA), respectively. Twenty-five placental samples were divided into lean (n=11), obesity (n=7) and overweight/obesity+GDM (n=7) groups. F₄-Neuroprostanes and F₂-Isoprostanes were higher in obesity compared to lean controls, but reduced to levels similar to lean women when obesity is further complicated with GDM. Lower content of F₂-Isoprostanes suggests adaptive placental responses in GDM attenuating oxidative stress. However, low levels of placental F₄-Neuroprostanes may indicate impaired DHA metabolism in GDM, affecting fetal development and offspring health. These results were not related to differences in placental content of DHA, AA and polyunsaturated fatty acids status nor to maternal diet or gestational weight gain. Placental DHA and AA metabolism differs in obesity and GDM, highlighting the importance of investigating the signalling roles of F₄-Neuroprostanes and F₂-Isoprostanes in the human term placenta.

Chemical inhibition of mitochondrial fission improves insulin signaling and subdues hyperglycemia induced stress in placental trophoblast cells

BACKGROUND

Gestational diabetes mellitus (GDM) is a metabolic complication that affects millions of pregnant women in the world. Placental tissue function is endangered by hyperglycemia during GDM, which is correlated to increased incidences of pregnancy complications. Recently we showed that due to a significant decrease in mitochondrial fusion, mitochondrial dynamics equilibrium is altered in placental tissues from GDM patients. Evidence for the role of reduced mitochondrial fusion in the disruption of mitochondrial function in placental cells is limited.

METHODS AND RESULTS

Here we show that chemical inhibition of mitochondrial fission in cultured placental trophoblast cells leads to an increase in mitochondrial fusion and improves the physiological state of these cells and hence, their capacity to cope in a hyperglycemic environment. Specifically, mitochondrial fission inhibition led to a reduction in reactive oxygen species (ROS) generation, mitochondrial unfolded protein marker expressions, and mitochondrial depolarization. It supported the increase in mitochondrial antioxidant enzyme expressions as well. Mitochondrial fission inhibition also increases the placental cell insulin sensitivity during hyperglycemia.

CONCLUSION

Our results suggest that mitochondrial fusion/fission equilibrium is critical for placental cell function and signify the therapeutic potential of small molecule inhibitors of fission during GDM.

Maternal obesity: new placental paradigms unfolded

The prevalence of maternal obesity is increasing at an alarming rate, and is providing a major challenge for obstetric practice. Adverse effects on maternal and fetal health are mediated by complex interactions between metabolic, inflammatory, and oxidative stress signaling in the placenta. Endoplasmic reticulum (ER) stress and activation of the unfolded protein response (UPR) are common downstream pathways of cell stress, and there is evidence that this conserved homeostatic response may be a key mediator in the pathogenesis of placental dysfunction. We summarize the current literature on the placental cellular and molecular changes that occur in obese women. A special focus is cast onto placental ER stress in obese pregnancy, which may provide a novel link for future investigation.

Maternal obesity-associated disruption of polarized lactate transporter MCT4 expression in human placenta

Maternal obesity is associated with an increased risk of adverse pregnancy outcomes including stillbirth, and their etiology is thought to be related to placental and fetal hypoxia. In this study, we sought to investigate the levels of lactate in maternal and umbilical cord blood, a well characterized biomarker for hypoxia, and expression of plasma membrane lactate transporter MCT1 and MCT4 in the placental syncytiotrophoblast (STB), which are responsible for lactate uptake and extrusion, respectively, from pregnant women with a diagnosis of obesity following a Cesarean delivery at term. With use of approaches including immunofluorescence staining, Western blot, RT-qPCR and ELISA, our results revealed that in controls the expression of MCT1 was equally observed between basal (fetal-facing, BM) and microvillous (maternal-facing, MVM) membrane of the STB, whereas MCT4 was predominantly expressed in the MVM but barely detected in the BM. However, obese patients demonstrated significant decreased MCT4 abundance in the MVM coupled with concurrent elevated expression in the BM. We also found a linear trend toward decreasing MCT4 expression ratio of MVM to BM with increasing maternal pre-pregnancy BMI. Furthermore, our data showed that the lactate ratios of fetal cord arterial to maternal blood were remarkably reduced in obese samples compared to their normal counterparts. Collectively, these results suggest that the loss of polarization of lactate transporter MCT4 expression in placental STB leading to disruption of unidirectional lactate transport from the fetal to the maternal compartment may constitute part of mechanisms linking maternal obesity and pathogenesis of stillbirth.

Epigenetic Profiling in the Saliva of Obese Pregnant Women

Maternal obesity is associated with inflammation and oxidative stress, strongly impacting the intrauterine environment with detrimental consequences for both mother and offspring. The saliva is a non-invasive biofluid reflecting both local and systemic health status. This observational study aimed to profile the epigenetic signature in the saliva of Obese (OB) and Normal-Weight (NW) pregnant women. Sixteen NW and sixteen OB Caucasian women with singleton spontaneous pregnancies were enrolled. microRNAs were quantified by the OpenArray Platform. The promoter region methylation of Suppressor of Cytokine Signaling 3 (SOCS3) and Transforming Growth Factor Beta 1 (TGF-Beta1) was assessed by pyrosequencing. There were 754 microRNAs evaluated: 20 microRNAs resulted in being differentially expressed between OB and NW. microRNA pathway enrichment analysis showed a significant association with the TGF-Beta signaling pathway (miTALOS) and with fatty acids biosynthesis/metabolism, lysine degradation, and ECM-receptor interaction pathways (DIANA-miRPath). Both SOCS3 and TGF-Beta1 were significantly down-methylated in OB vs. NW. These results help to clarify impaired mechanisms involved in obesity and pave the way for the understanding of specific damaged pathways. The characterization of the epigenetic profile in saliva of pregnant women can represent a promising tool for the identification of obesity-related altered mechanisms and of possible biomarkers for early diagnosis and treatment of pregnancy-adverse conditions.

Dynamic and Systemic Perspective in Autism Spectrum Disorders: A Change of Gaze in Research Opens to A New Landscape of Needs and Solutions

The first step for a harmonious bio-psycho-social framework in approaching autism spectrum disorders (ASD) is overcoming the conflict between the biological and the psychosocial perspective. Biological research can provide clues for a correct approach to clinical practice, assuming that it would lead to the conceptualization of a pathogenetic paradigm able to account for epidemiologic and clinical findings. The upward trajectory in ASD prevalence and the systemic involvement of other organs besides the brain suggest that the epigenetic paradigm is the most plausible one. The embryo-fetal period is the crucial window of opportunity for keeping neurodevelopment on the right tracks, suggesting that women's health in pregnancy should be a priority. Maladaptive molecular pathways beginning in utero, in particular, a vicious circle between the immune response, oxidative stress/mitochondrial dysfunction, and dysbiosis-impact neurodevelopment and brain functioning across the lifespan and are the basis for progressive multisystemic disorders that account for the substantial health loss and the increased mortality in ASD. Therefore, the biological complexity of ASD and its implications for health requires the enhancement of clinical skills on these topics, to achieve an effective multi-disciplinary healthcare model. Well-balanced training courses could be a promising starting point to make a change.

Mitochondrial and Oxidative Unbalance in Placentas from Mothers with SARS-CoV-2 Infection

SARS-CoV-2 infection has been related to adverse pregnancy outcomes. A placental role in protecting the fetus from SARS-CoV-2 infection has been documented. Nevertheless, it is still unclear how the placenta is affected in SARS-CoV-2 infection. Here we assessed placental mitochondrial (mt) and oxidative features in COVID-19 and healthy mothers. mtDNA levels, DNA oxidative damage, expression levels of genes involved in antioxidant defenses, mitochondrial dynamics and respiratory chain subunits were investigated in placentas from singleton pregnancies of 30 women with SARS-CoV-2 infection during the third trimester (12 asymptomatic, 18 symptomatic) and 16 controls. mtDNA levels decreased in COVID-19 placentas vs. controls and inversely correlated with DNA oxidative damage, which increased in the symptomatic group. Antioxidant gene expressions decreased in SARS-CoV-2 mothers (CAT, GSS). Symptomatic cases also showed a lower expression of respiratory chain (NDUFA9, SDHA, COX4I1) and mt dynamics (DNM1L, FIS1) genes. Alterations in placental mitochondrial features and oxidative balance in COVID-19-affected mothers might be due to the impaired intrauterine environment, generated by systemic viral effects, leading to a negative vicious circle that worsens placental oxidative stress and mitochondrial efficiency. This likely causes cell homeostasis dysregulations, raising the potential of possible long-term effects.

Prenatal exercise in fetal development: a placental perspective

Maternal obesity (MO) and gestational diabetes mellitus (GDM) are common in Western societies, which impair fetal development and predispose offspring to metabolic dysfunction. Placenta is the organ linking the mother to her fetus, and MO suppresses the development of vascular system and expression of nutrient transporters in placenta, thereby affecting fetal development. For maintaining its proper physiological function, placenta is energy demanding, which is met through extensive oxidative phosphorylation. However, the oxidative capacity of placenta is suppressed due to MO and GDM. Recently, several studies showed that physical activity during pregnancy enhances oxidative metabolism and improves placental function, which might be partially mediated by exerkines, referring to cytokines elicited by exercise. In addition, as an endocrine organ, placenta secretes cytokines, termed placentokines, including apelin, superoxide dismutase 3, irisin, and adiponectin, which mediate fetal development and maternal metabolism. Possible molecular mechanisms linking maternal exercise and placentokines to placental and fetal development are further discussed. As an emerging field, up to now, available studies are limited, mostly conducted in rodents. Given the epidemics of obesity and metabolic disorders, as well as the prevalence of maternal sedentary lifestyle, the effects of exercise of pregnant women on placental function and placentokine secretion, as well as their impacts on fetal development, need to be further examined.

Placental pathology in COVID-19 affected pregnant women: A prospective case-control study

INTRODUCTION

During pregnancy, SARS-CoV-2 infection may cause an abnormal development of the placenta, thus influencing maternal and fetal outcomes. Few studies have reported data on placental morphology and histology in infected pregnant patients, although not compared with carefully matched controls. The aim of this study is to compare placental morphology and histology of pregnant women affected by SARS-CoV-2 to non-infected controls.

METHODS

This is a prospective multicenter case-control study on 64 pregnant women affected by SARS-CoV-2 who delivered at term or late-preterm. Data were collected about pregnancy course, maternal and fetal outcomes, placental biometry and macro- and microscopical morphology. 64 not-infected women were identified as controls, matched by age, body mass index and ethnicity.

RESULTS

Cases and controls had similar fetal and maternal outcomes. No significant differences were observed in placental macro- or microscopical morphology between the two groups. In the cases treated with antivirals, chloroquine, LMWH or antibiotics, placentas were heavier but not more efficient than the non-treated, since the fetal/placental weight ratio did not differ. Moreover, delayed villous maturation was more frequent in treated women, although not significantly. The newborns whose mothers received oxygen therapy as treatment had higher levels of umbilical cord pO₂ at birth.

DISCUSSION

In this prospective case-control study, SARS-CoV-2 infection during the third trimester did not influence placental histological pattern. Pharmacological and oxygen therapy administered to women affected by this viral infection could impact maternal and fetal outcomes and be associated to placental histological alterations.

Effects of Maternal Obesity On Placental Phenotype

The incidence of obesity is rising rapidly worldwide with the consequence that more women are entering pregnancy overweight or obese. This leads to an increased incidence of clinical complications during pregnancy and of poor obstetric outcomes. The offspring of obese pregnancies are often macrosomic at birth although there is also a subset of the progeny that are growth-restricted at term. Maternal obesity during pregnancy is also associated with cardiovascular, metabolic and endocrine dysfunction in the offspring later in life. As the interface between the mother and fetus, the placenta has a central role in programming intrauterine development and is known to adapt its phenotype in response to environmental conditions such as maternal undernutrition and hypoxia. However, less is known about placental function in the abnormal metabolic and endocrine environment associated with maternal obesity during pregnancy. This review discusses the placental consequences of maternal obesity induced either naturally or experimentally by increasing maternal nutritional intake and/or changing the dietary composition. It takes a comparative, multi-species approach and focusses on placental size, morphology, nutrient transport, metabolism and endocrine function during the later stages of obese pregnancy. It also examines the interventions that have been made during pregnancy in an attempt to alleviate the more adverse impacts of maternal obesity on placental phenotype. The review highlights the potential role of adaptations in placental phenotype as a contributory factor to the pregnancy complications and changes in fetal growth and development that are associated with maternal obesity.

Placental Antioxidant Defenses and Autophagy-Related Genes in Maternal Obesity and Gestational Diabetes Mellitus

Maternal obesity and gestational diabetes mellitus (GDM) are increasing worldwide, representing risk factors for both mother and child short/long-term outcomes. Oxidative stress, lipotoxicity and altered autophagy have already been reported in obesity, but few studies have focused on obese pregnant women with GDM. Antioxidant and macro/chaperone-mediated autophagy (CMA)-related gene expressions were evaluated herein in obese and GDM placentas. A total of 47 women with singleton pregnancies delivered by elective cesarean section were enrolled: 16 normal weight (NW), 18 obese with no comorbidities (OB GDM(–)), 13 obese with GDM (OB GDM(+)). Placental gene expression was assessed by real-time PCR. Antioxidant gene expression (CAT, GPX1, GSS) decreased, the pro-autophagic ULK1 gene increased and the chaperone-mediated autophagy regulator PHLPP1 decreased in OB GDM(–) vs. NW. On the other hand, PHLPP1 expression increased in OB GDM(+) vs. OB GDM(–). When analyzing results in relation to fetal sex, we found sexual dimorphism for both antioxidant and CMA-related gene expressions. These preliminary results can pave the way for further analyses aimed at elucidating the placental autophagy role in metabolic pregnancy disorders and its potential targetability for the treatment of diabetes outcomes.

Maternal Low-Grade Chronic Inflammation and Intrauterine Programming of Health and Disease

Overweight and obesity during pregnancy have been associated with increased birth weight, childhood obesity, and noncommunicable diseases in the offspring, leading to a vicious transgenerational perpetuating of metabolic derangements. Key components in intrauterine developmental programming still remain to be identified. Obesity involves chronic low-grade systemic inflammation that, in addition to physiological adaptations to pregnancy, may potentially expand to the placental interface and lead to intrauterine derangements with a threshold effect. Animal models, where maternal inflammation is mimicked by single injections with lipopolysaccharide (LPS) resembling the obesity-induced immune profile, showed increased adiposity and impaired metabolic homeostasis in the offspring, similar to the phenotype observed after exposure to maternal obesity. Cytokine levels might be specifically important for the metabolic imprinting, as cytokines are transferable from maternal to fetal circulation and have the capability to modulate placental nutrient transfer. Maternal inflammation may induce metabolic reprogramming at several levels, starting from the periconceptional period with effects on the oocyte going through early stages of embryonic and placental development. Given the potential to reduce inflammation through inexpensive, widely available therapies, examinations of the impact of chronic inflammation on reproductive and pregnancy outcomes, as well as preventive interventions, are now needed.

Autism Spectrum Disorder from the Womb to Adulthood: Suggestions for a Paradigm Shift

The wide spectrum of unique needs and strengths of Autism Spectrum Disorders (ASD) is a challenge for the worldwide healthcare system. With the plethora of information from research, a common thread is required to conceptualize an exhaustive pathogenetic paradigm. The epidemiological and clinical findings in ASD cannot be explained by the traditional linear genetic model, hence the need to move towards a more fluid conception, integrating genetics, environment, and epigenetics as a whole. The embryo-fetal period and the first two years of life (the so-called 'First 1000 Days') are the crucial time window for neurodevelopment. In particular, the interplay and the vicious loop between immune activation, gut dysbiosis, and mitochondrial impairment/oxidative stress significantly affects neurodevelopment during pregnancy and undermines the health of ASD people throughout life. Consequently, the most effective intervention in ASD is expected by primary prevention aimed at pregnancy and at early control of the main effector molecular pathways. We will reason here on a comprehensive and exhaustive pathogenetic paradigm in ASD, viewed not just as a theoretical issue, but as a tool to provide suggestions for effective preventive strategies and personalized, dynamic (from womb to adulthood), systemic, and interdisciplinary healthcare approach.

The Influence of Obesity and Associated Fatty Acids on Placental Inflammation

PURPOSE

Maternal obesity, affecting nearly 1 in 4 pregnancies, is associated with increased circulating saturated fatty acids, such as palmitate. These fatty acids are implicated in placental inflammation, which may in turn exacerbate both maternal-fetal tolerance and responses to pathogens, such as group B Streptococcus. In this review, we address the question, "How do obesity and associated fatty acids influence placental inflammation?"

METHODS

In this narrative review, we searched PubMed and Google Scholar using combinations of the key words placental inflammation or pregnancy and lipids, fatty acids, obesity, palmitate, or other closely related search terms. We also used references found within these articles that may have been absent from our original search queries. We analyzed methods and key results of these articles to compare and contrast their findings, which were occasionally at odds with each other.

FINDINGS

Although obesity can be studied as a whole, complex phenomena with in vivo mouse models and human samples from patients with obesity, in vitro modeling often relies on the treatment of cells or tissues with ≥1 fatty acids and occasionally other compounds (eg, glucose and insulin). We found that palmitate, most commonly used in vitro to recreate hallmarks of obesity, induces apoptosis, oxidative stress, mitochondrial dysfunction, autophagy defects, and inflammasome activation in many placental cell types. We compare this to in vivo models of obesity wherever possible. We found that obesity as a whole may have more complex regulation of these phenomena (apoptosis, oxidative stress, mitochondrial dysfunction, autophagy defects, and inflammasome activation) compared with in vitro models of fatty acid treatment (primarily palmitate) because of the presence of unsaturated fatty acids (ie, oleate), which may have anti-inflammatory effects.

IMPLICATIONS

The interaction of unsaturated fatty acids with saturated fatty acids may ameliorate many inflammatory effects of saturated fatty acids alone, which complicates interpretation of in vitro studies that focus on a particular fatty acid in isolation. This complication may explain why certain studies of obesity in vivo have differing outcomes from studies of specific fatty acids in vitro.

Placental mitochondrial function in response to gestational exposures

Poor environmental conditions, including malnutrition, hypoxia and obesity in the mother increase the risk of pregnancy complications, such as pre-eclampsia and gestational diabetes mellitus, which impacts the lifelong health of the mother and her offspring. The placenta plays an important role in determining pregnancy outcome by acting as an exchange interface and endocrine hub to support fetal growth. Mitochondria are energy powerhouses of cells that fuel placental physiology throughout pregnancy, including placental development, substrate exchange and hormone secretion. They are responsive to environmental cues and changes in mitochondrial function may serve to mediate or mitigate the impacts of poor gestational environments on placental physiology and hence, the risks of pregnancy complications. Thus, a more integrated understanding about the role of placental mitochondria in orchestrating changes in relation to environmental conditions and pregnancy outcome is paramount. This review summarises the functions of mitochondria in the placenta and findings from humans and experimental animals that demonstrate how mitochondrial structure and function are altered in different gestational environments (namely complicated pregnancies and adverse environmental conditions). Together the available data suggest that mitochondria in the placenta play a major role in determining placental physiology, fetal growth and pregnancy outcome.

Placental mitochondrial dysfunction with metabolic diseases: Therapeutic approaches

Both obesity and gestational diabetes mellitus (GDM) lead to poor maternal and fetal outcomes, including pregnancy complications, fetal growth issues, stillbirth, and developmental programming of adult-onset disease in the offspring. Increased placental oxidative/nitrative stress and reduced placental (trophoblast) mitochondrial respiration occur in association with the altered maternal metabolic milieu of obesity and GDM. The effect is particularly evident when the fetus is male, suggesting a sexually dimorphic influence on the placenta. In addition, obesity and GDM are associated with inflexibility in trophoblast, limiting the ability to switch between usage of glucose, fatty acids, and glutamine as substrates for oxidative phosphorylation, again in a sexually dimorphic manner. Here we review mechanisms underlying placental mitochondrial dysfunction: its relationship to maternal and fetal outcomes and the influence of fetal sex. Prevention of placental oxidative stress and mitochondrial dysfunction may improve pregnancy outcomes. We outline pathways to ameliorate deficient mitochondrial respiration, particularly the benefits and pitfalls of mitochondria-targeted antioxidants.

Effects of α-lipoic acid and myo-inositol supplementation on the oocyte environment of infertile obese women: A preliminary study

Obesity is becoming pandemic and is associated with impaired reproductive potential. Oxidative stress, low-grade chronic inflammation and mitochondrial dysfunctions, which characterize obesity, strongly affect oocyte environment and function. Supplementation with antioxidant and anti-inflammatory compounds has been suggested to improve fertility. Here we evaluated the effect of α-lipoic acid and myo-inositol supplementation on the oocyte environment of infertile obese women. Nineteen normal-weight and twenty-three obese women, infertile for non-ovarian reasons, were recruited. For two months before ovarian stimulation, all women received 400 μg/die folic acid, whereas 15 obese were additionally supplemented with 800 mg α-lipoic acid, 2 g myo-inositol/die. Antioxidant capacity was measured in follicular fluid by enzymatic assay; mitochondrial DNA (mtDNA) content and mRNA levels of two respiratory chain subunits were analyzed in granulosa cells by Real-time PCR. Pregnancy rate was similar between normal-weight and treated obese, and lower in untreated obese patients. Supplemented women showed significantly higher antioxidant levels in follicular fluid compared to the two groups taking only folic acid. Conversely, granulosa cells mtDNA content was decreased in treated and higher in untreated obese patients compared to normal-weight women, suggesting mtDNA increases to compensate for oxidative-stress damages. Reduced expression of respiratory subunits in untreated obese may confirm mitochondria impairment. Interestingly, mtDNA levels inversely correlated to both total and metaphase II oocyte number. In this preliminary study, combined supplementation of α-lipoic acid and myo-inositol in infertile obese women was associated with amelioration in the oxidative status of the oocyte environment, possibly contributing to a higher pregnancy rate.

Mitochondrial dysfunction in placental trophoblast cells experiencing gestational diabetes mellitus

KEY POINTS

Mitochondrial dysfunction is known to occur in diabetic phenotypes including type 1 and 2 diabetes mellitus. The incidence of gestational diabetes mellitus (GDM) is increasing and defined as the onset of a diabetic phenotype during pregnancy. The role of placental mitochondria in the aetiology of GDM remains unclear and is an emerging area of research. Differing mitochondrial morphologies within the placenta may influence the pathogenesis of the disorder. This study observed mitochondrial dysfunction in GDM placenta when assessing whole tissue. Upon further investigation into mitochondrial isolates from the cytotrophoblast and syncytiotrophoblast, mitochondrial dysfunction appears exaggerated in syncytiotrophoblast. Assessing mitochondrial populations individually enabled the determination of differences between cell lineages of the placenta and established varying levels of mitochondrial dysfunction in GDM, in some instances establishing significance in pathways previously inconclusive or confounded when assessing whole tissue. This research lays the foundation for future work into mitochondrial dysfunction in the placenta and the role it may play in the aetiology of GDM.

ABSTRACT

Mitochondrial dysfunction has been associated with diabetic phenotypes, yet the involvement of placental mitochondria in gestational diabetes mellitus (GDM) remains inconclusive. This is in part complicated by the different mitochondrial subpopulations present in the two major trophoblast cell lineages of the placenta. To better elucidate the role of mitochondria in this pathology, this study examined key aspects of mitochondrial function in placentas from healthy pregnancies and those complicated by GDM in both whole tissue and isolated mitochondria. Mitochondrial content, citrate synthase activity, reactive oxygen species production and gene expression regulating metabolic, hormonal and antioxidant control was examined in placental tissue, before examining functional differences between mitochondrial isolates from cytotrophoblast (Cyto-Mito) and syncytiotrophoblast (Syncytio-Mito). Our study observed evidence of mitochondrial dysfunction across multiple pathways when assessing whole placental tissue from GDM pregnancies compared with healthy controls. Furthermore, by examining isolated mitochondria from the cytotrophoblast and syncytiotrophoblast cell lineages of the placenta we established that although both mitochondrial populations were dysfunctional, they were differentially impacted. These data highlight the need to consider changes in mitochondrial subpopulations at the feto-maternal interface when studying pregnancy pathologies.

Placental proteome abnormalities in women with gestational diabetes and large-for-gestational-age newborns

INTRODUCTION

Gestational diabetes mellitus (GDM) is the most frequent metabolic complication during pregnancy and is associated with development of short-term and long-term complications for newborns, with large-for-gestational-age (LGA) being particularly common. Interestingly, the mechanism behind altered fetal growth in GDM is only partially understood.

RESEARCH DESIGN AND METHODS

A proteomic approach was used to analyze placental samples obtained from healthy pregnant women (n=5), patients with GDM (n=12) and with GDM and LGA (n=5). Effects of altered proteins on fetal development were tested in vitro in human embryonic stem cells (hESCs).

RESULTS

Here, we demonstrate that the placental proteome is altered in pregnant women affected by GDM with LGA, with at least 37 proteins differentially expressed to a higher degree (p<0.05) as compared with those with GDM but without LGA. Among these proteins, 10 are involved in regulating tissue differentiation and/or fetal growth and development, with bone marrow proteoglycan (PRG2) and dipeptidyl peptidase-4 (DPP-4) being highly expressed. Both PRG2 and DPP-4 altered the transcriptome profile of stem cells differentiation markers when tested in vitro in hESCs, suggesting a potential role in the onset of fetal abnormalities.

CONCLUSIONS

Our findings suggest that placental dysfunction may be directly responsible for abnormal fetal growth/development during GDM. Once established on a larger population, inhibitors of the pathways involving those altered factors may be tested in conditions such as GDM and LGA, in which therapeutic approaches are still lacking.

Mitochondrial dysfunction in the fetoplacental unit in gestational diabetes mellitus

Gestational diabetes mellitus (GDM) is a disease of pregnancy that is associated with d-glucose intolerance and foeto-placental vascular dysfunction. GMD causes mitochondrial dysfunction in the placental endothelium and trophoblast. Additionally, GDM is associated with reduced placental oxidative phosphorylation due to diminished activity of the mitochondrial F₀F₁-ATP synthase (complex V). This phenomenon may result from a higher generation of reactive superoxide anion and nitric oxide. Placental mitochondrial biogenesis and mitophagy work in concert to maintain cell homeostasis and are vital mechanisms securing the efficient generation of ATP, whose demand is higher in pregnancy, ensuring foetal growth and development. Additional factors disturbing placental ATP synthase activity in GDM include pre-gestational maternal obesity or overweight, intracellular pH, miRNAs, fatty acid oxidation, and foetal (and 'placental') sex. GDM is also associated with maternal and foetal hyperinsulinaemia, altered circulating levels of adiponectin and leptin, and the accumulation of extracellular adenosine. Here, we reviewed the potential interplay between these molecules or metabolic conditions on the mechanisms of mitochondrial dysfunction in the foeto-placental unit in GDM pregnancies.

Fetal circulating human resistin increases in diabetes during pregnancy and impairs placental mitochondrial biogenesis

Background

Diabetes during pregnancy affects placental mitochondrial content and function, which has the potential to impact fetal development and the long-term health of offspring. Resistin is a peptide hormone originally discovered in mice as an adipocyte-derived factor that induced insulin resistance. In humans, resistin is primarily secreted by monocytes or macrophages. The regulation and roles of human resistin in diabetes during pregnancy remain unclear.

Methods

Fetal resistin levels were measured in cord blood from pregnancies with (n = 42) and without maternal diabetes (n = 81). Secretion of resistin from cord blood mononuclear cells (CBMCs) was measured. The actions of human resistin in mitochondrial biogenesis were determined in placental trophoblastic cells (BeWo cells) or human placental explant.

Results

Concentrations of human resistin in cord sera were higher in diabetic pregnancies (67 ng/ml) compared to healthy controls (50 ng/ml, P < 0.05), and correlated (r = 0.4, P = 0.002) with a measure of maternal glycemia (glucose concentration 2 h post challenge). Resistin mRNA was most abundant in cord blood mononuclear cells (CBMCs) compared with placenta and mesenchymal stem cells (MSCs). Secretion of resistin from cultured CBMCs was increased in response to high glucose (25 mM). Exposing BeWo cells or human placental explant to resistin decreased expression of peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α), mitochondrial abundance, and ATP production.

Conclusions

Resistin is increased in fetal circulation of infants exposed to the diabetic milieu, potentially reflecting a response of monocytes/macrophages to hyperglycemia and metabolic stresses associated with diabetes during pregnancy. Increased exposure to resistin may contribute to mitochondrial dysfunction and aberrant energy metabolism characteristic of offspring exposed to diabetes in utero.

Nutrients, Mitochondrial Function, and Perinatal Health

Mitochondria are active independent organelles that not only meet the cellular energy requirement but also regulate central cellular activities. Mitochondria can play a critical role in physiological adaptations during pregnancy. Differences in mitochondrial function have been found between healthy and complicated pregnancies. Pregnancy signifies increased nutritional requirements to support fetal growth and the metabolism of maternal and fetal tissues. Nutrient availability regulates mitochondrial metabolism, where excessive macronutrient supply could lead to oxidative stress and contribute to mitochondrial dysfunction, while micronutrients are essential elements for optimal mitochondrial processes, as cofactors in energy metabolism and/or as antioxidants. Inadequate macronutrient and micronutrient consumption can result in adverse pregnancy outcomes, possibly through mitochondrial dysfunction, by impairing energy supply, one-carbon metabolism, biosynthetic pathways, and the availability of metabolic co-factors which modulate the epigenetic processes capable of establishing significant short- and long-term effects on infant health. Here, we review the importance of macronutrients and micronutrients on mitochondrial function and its influence on maternal and infant health.

Placental function in maternal obesity

Maternal obesity is associated with pregnancy complications and increases the risk for the infant to develop obesity, diabetes and cardiovascular disease later in life. However, the mechanisms linking the maternal obesogenic environment to adverse short- and long-term outcomes remain poorly understood. As compared with pregnant women with normal BMI, women entering pregnancy obese have more pronounced insulin resistance, higher circulating plasma insulin, leptin, IGF-1, lipids and possibly proinflammatory cytokines and lower plasma adiponectin. Importantly, the changes in maternal levels of nutrients, growth factors and hormones in maternal obesity modulate placental function. For example, high insulin, leptin, IGF-1 and low adiponectin in obese pregnant women activate mTOR signaling in the placenta, promoting protein synthesis, mitochondrial function and nutrient transport. These changes are believed to increase fetal nutrient supply and contribute to fetal overgrowth and/or adiposity in offspring, which increases the risk to develop disease later in life. However, the majority of obese women give birth to normal weight infants and these pregnancies are also associated with activation of inflammatory signaling pathways, oxidative stress, decreased oxidative phosphorylation and lipid accumulation in the placenta. Recent bioinformatics approaches have expanded our understanding of how maternal obesity affects the placenta; however, the link between changes in placental function and adverse outcomes in obese women giving birth to normal sized infants is unclear. Interventions that specifically target placental function, such as activation of placental adiponectin receptors, may prevent the transmission of metabolic disease from obese women to the next generation.

Investigating mitochondrial dysfunction in gestational diabetes mellitus and elucidating if BMI is a causative mediator

OBJECTIVE

Gestational diabetes mellitus (GDM) is defined as any degree of glucose intolerance which is diagnosed during pregnancy and poses considerable health risks for mother and child. Maternal body mass index (BMI) correlates with GDM diagnosis and the pathophysiology of this link may be explained through oxidative stress and mitochondrial dysfunction. In this study we investigate if mitochondrial dysfunction is evident in GDM by measuring cell free mitochondrial DNA concentration and determine if a potential relationship exists between maternal mitochondrial function and GDM diagnosis.

STUDY DESIGN

Plasma samples were taken at 20 weeks' gestation from women who subsequently developed GDM (n = 44) and matched with women with uncomplicated pregnancies (n = 85) as controls. Control group 1 was matched by maternal age and BMI (n = 41) to GDM cases, while control group 2 was matched by maternal age alone (n = 44). Prediction potential was determined by binary regression analysis. Statistical analysis was performed on SPSS Statistics v25.

RESULTS

Binary regression analysis showed a statistically significant association between mtDNA concentration and GDM diagnosis (p = 0.032) in GDM cases versus control group 2, indicating that GDM patients have higher circulating mtDNA concentrations relative to healthy control patients. The lack of statistical significance in control group 1 suggests that BMI may be linked to mitochondrial function in GDM patients.

CONCLUSION

These results demonstrate a potential pathogenic role for mitochondrial dysfunction in GDM, with BMI presenting as a likely physiological mediator.

Role of metformin in epigenetic regulation of placental mitochondrial biogenesis in maternal diabetes

Adverse maternal environments, such as diabetes and obesity, impair placental mitochondrial function, which affects fetal development and offspring long-term health. The underlying mechanisms and effective interventions to abrogate such effect remain unclear. Our previous studies demonstrated impaired mitochondrial biogenesis in male human placenta of diabetic mothers. In the present studies, epigenetic marks possibly related to mitochondrial biogenesis in placentae of women with diabetes (n = 23) and controls (n = 23) were analyzed. Effects of metformin were examined in human placental explants from a subgroup of diabetic women and in a mouse model of maternal high fat diet feeding. We found that maternal diabetes was associated with epigenetic regulation of mitochondrial biogenesis in human placenta in a fetal sex-dependent manner, including decreased histone acetylation (H3K27 acetylation) and increased promoter methylation of peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α). In male placenta, the levels of H3K27 acetylation and PGC-1α promoter methylation correlated significantly with the activity of AMP-activated protein kinase (AMPK). Metformin treatment on male diabetic placental explant activated AMPK and stimulated PGC-1α expression, concomitant with increased H3K27 acetylation and decreased PGC-1α promoter methylation. In vivo, we show that maternal metformin treatment along with maternal high fat diet significantly increased mouse placental abundance of PGC-1α expression and downstream mitochondrial transcription factor A (TFAM) and inhibited maternal high fat diet-impaired placental efficiency and glucose tolerance in offspring. Together, these findings suggest the capability of metformin to stimulate placental mitochondrial biogenesis and inhibit the aberrant epigenetic alterations occurring in maternal diabetes during pregnancy, conferring protective effects on offspring.

Increased placental mitochondrial fusion in gestational diabetes mellitus: an adaptive mechanism to optimize feto-placental metabolic homeostasis?

INTRODUCTION

Gestational diabetes mellitus (GDM), a common pregnancy disorder, increases the risk of fetal overgrowth and later metabolic morbidity in the offspring. The placenta likely mediates these sequelae, but the exact mechanisms remain elusive. Mitochondrial dynamics refers to the joining and division of these organelles, in attempts to maintain cellular homeostasis in stress conditions or alterations in oxygen and fuel availability. These remodeling processes are critical to optimize mitochondrial function, and their disturbances characterize diabetes and obesity.

METHODS AND RESULTS

Herein we show that placental mitochondrial dynamics are tilted toward fusion in GDM, as evidenced by transmission electron microscopy and changes in the expression of key mechanochemical enzymes such as OPA1 and active phosphorylated DRP1. In vitro experiments using choriocarcinoma JEG-3 cells demonstrated that increased exposure to insulin, which typifies GDM, promotes mitochondrial fusion. As placental ceramide induces mitochondrial fission in pre-eclampsia, we also examined ceramide content in GDM and control placentae and observed a reduction in placental ceramide enrichment in GDM, likely due to an insulin-dependent increase in ceramide-degrading ASAH1 expression.

CONCLUSIONS

Placental mitochondrial fusion is enhanced in GDM, possibly as a compensatory response to maternal and fetal metabolic derangements. Alterations in placental insulin exposure and sphingolipid metabolism are among potential contributing factors. Overall, our results suggest that GDM has profound impacts on placental mitochondrial dynamics and metabolism, with plausible implications for the short-term and long-term health of the offspring.

Mechanism of Placenta Damage in Gestational Diabetes Mellitus by Investigating TXNIP of Patient Samples and Gene Functional Research in Cell Line

INTRODUCTION

Gestational diabetes mellitus (GDM) is a gestational complication that affects maternal and child health. The placenta provides the fetus with the necessary nutrition and oxygen and takes away the metabolic waste. Patients with GDM are diagnosed and treated merely on the basis of the blood glucose level; this approach does nothing to help evaluate the status of the placenta, which is worth noting in GDM. The purpose of this research was to clarify the relation between thioredoxin-interacting protein (TXNIP) and reactive oxygen species (ROS) in the placenta of patients with GDM, which has thus far remained unclear.

METHODS

The expression of TXNIP in the placentas of 10 patients with GDM and 10 healthy puerperae (control group) was investigated via immunofluorescence. The relation among TXNIP, ROS, and the function of mitochondria was explored in HTR-8/SVneo cells stimulated by high glucose (HG).

RESULTS

The results showed the expression of TXNIP in the placentas of patients with GDM was higher than that in the control group, and the expression of TXNIP in HTR-8/SVneo cells treated with HG was higher than that in the control group, causing the accumulation of ROS and changes of mitochondria, promoting apoptosis and inhibition of migration.

CONCLUSIONS

High expression of TXNIP caused by HG mediates the increasing ROS and the mitochondria dysfunction in GDM; this impairs the function of the placenta and is the basis for the prediction of perinatal outcome.

Placental mitochondria and reactive oxygen species in the physiology and pathophysiology of pregnancy

Mitochondria are central to cell function. The placenta forms the interface between maternal and fetal systems, and placental mitochondria have critical roles in maintaining pregnancy. The placenta is unusual in having two adjacent cell layers (cytotrophoblasts and the syncytiotrophoblast) with vastly different mitochondria that have distinct functions in health and disease. Mitochondria both produce the majority of reactive oxygen species (ROS), and are sensitive to ROS. ROS are important in allowing cells to sense their environment through mitochondrial-centred signalling, and this signalling also helps cells/tissues adapt to changing environments. However, excessive ROS are damaging, and increased ROS levels are associated with pregnancy complications, including the important disorders preeclampsia and gestational diabetes mellitus. Here we review the function of placental mitochondria in healthy pregnancy, and also in pregnancy complications. Placental mitochondria are critical to cell function, and mitochondrial damage is a feature of pregnancy complications. However, the responsiveness of mitochondria to ROS signalling may be central to placental adaptations that mitigate damage, and placental mitochondria are an attractive target for the development of therapeutics to improve pregnancy outcomes.

Placental ESRRG-CYP19A1 Expressions and Circulating 17-Beta Estradiol in IUGR Pregnancies

Introduction: Sex steroids are regulating factors for intrauterine growth. 17-β Estradiol (E2) is particularly critical to a physiological pregnancy, as increased maternal E2 was correlated to lower fetal weight at delivery. The placenta itself is a primary source of estrogens, synthetized from cholesterol precursors. Cytochrome P450 aromatase (encoded by CYP19A1 gene) is a rate-limiting enzyme for E2 biosynthesis. CYP19A1 transcription is supported by Estrogen Related-Receptor Gamma (ERRγ- ESRRG gene), which thus has an indirect role in placental steroidogenesis. Here we investigated maternal E2 levels and placental CYP19A1 and ESRRG expressions in pregnancies with IntraUterine Growth Restriction (IUGR). Methods: Singleton pregnancies were studied. E2 was measured in maternal plasma by electrochemiluminescence in 16 term controls and 11 IUGR (classified by umbilical artery doppler pulsatility index) at elective cesarean section, and also in 13 controls during pregnancy at a gestational age comparable to IUGR. CYP19A1 and ESRRG expressions were analyzed in placental tissue. Maternal/fetal characteristics, placental and molecular data were compared among study groups and tested for correlations. Results: Maternal E2 plasma concentrations were significantly decreased in IUGR compared to controls at delivery. When analyzing normal pregnancies at a gestational age similar to IUGR, E2 levels were not different to pathological cases. However, E2 levels at delivery positively correlated with placental efficiency. Placental CYP19A1 levels were significantly higher in IUGR placental tissue vs. controls, and specifically increased in female IUGR placentas. ESRRG expression was not different among groups. Discussion: We report a positive correlation between 17-β Estradiol levels and placental efficiency, that might indicate a disrupted steroidogenesis in IUGR pregnancies. Moreover, we show alterations of CYP19A1 expression in IUGR placentas, possibly indicating a compensatory effect to the adverse IUGR intrauterine environment, also depending on fetal sex. Further studies are needed to deeper investigate IUGR alterations in the complex interaction among molecules involved in placental steroidogenesis.