Inositol phosphoglycans and signal transduction systems in pregnancy in preeclampsia and diabetes: evidence for a significant regulatory role in preeclampsia at placental and systemic levels

Placenta and maternal endothelium during preeclampsia: Disruption of the glycocalyx explains increased inositol phosphoglycans and angiogenic factors in maternal blood

The etiology of the pregnancy syndrome preeclampsia is still unclear, while most hypotheses center on the placenta as the major contributor of the syndrome. Especially changes of the placental metabolism, including the use of glucose to produce energy, are important features. As an example, inositol phosphoglycan P-type molecules, second messengers involved in the glucose metabolism of all cells, can be retrieved from maternal urine of preeclamptic women, even before the onset of clinical symptoms. Alterations in the placental metabolism may subsequently lead to negative effects on the plasma membrane of the placental syncytiotrophoblast. This in turn may have deleterious effects on the glycocalyx of this layer and a disruption of this layer in all types of preeclampsia. The interruption of the glycocalyx in preeclampsia may result in changes of inositol phosphoglycan P-type signaling pathways and the release of these molecules as well as the release of soluble receptors such as sFlt-1 and sEndoglin. The release of placental factors later affects the maternal endothelium and disrupts the endothelial glycocalyx as well. This in turn may pave the way for edema, endothelial dysfunction, coagulation, all typical symptoms of preeclampsia.

Myo-inositol oxygenese activity in second trimester of pregnancy: altered myoinositol catabolism in gestational diabetes mellitus

OBJECTIVE

We aimed to determine myo-inositol oxygenase (MIOX) activity in gestational diabetes mellitus (GDM).

MATERIAL AND METHODS

The insulin, HbA1c, and MIOX levels of 80 pregnant women were analysed after 75 g OGTT. Group I included patients with no risk factor for GDM, Group II: patients with high risk for GDM, and Group III: GDM patients.

RESULTS

Fasting plasma glucose and Homeostatic Model Assessment for Insulin Resistance index were significantly higher in GDM cases (Group 3). Regarding the MIOX levels, significantly higher levels were recorded at 0-h in Group 3 compared to Groups 1 and 2. Significant alteration in MIOX activity was found between 0- and 2-h in Group 3 compared to Groups 1 and 2 (p < .029).

CONCLUSIONS

MIOX levels were higher in GDM cases so, it may be have a role in myo-inositol catabolism.

Hyperandrogenism and Polycystic ovary syndrome: Effects in pregnancy and offspring development

Polycystic ovary syndrome (PCOS) is one of the major endocrine disorders affecting women of reproductive age. Its etiology remains unclear. It is suggested that environmental factors, and particularly the intrauterine environment, play key roles in PCOS development. Besides the role of androgens in PCOS pathogenesis, exposure to endocrine disruptors, as is Bisphenol A, could also contribute to its development. Although PCOS is considered one of the leading causes of ovarian infertility, many PCOS patients can get pregnant. Some of them by natural conception and others by assisted reproductive technique treatments. As hyperandrogenism (one of PCOS main features) affects ovarian and uterine functions, PCOS women, despite reaching pregnancy, could present high-risk pregnancies, including implantation failure, an increased risk of gestational diabetes, preeclampsia, and preterm birth. Moreover, hyperandrogenism may also be maintained in these women during pregnancy. Therefore, as an altered uterine milieu, including hormonal imbalance, could affect the developing organisms, monitoring these patients throughout pregnancy and their offspring development is highly relevant. The present review focuses on the impact of androgenism and PCOS on fertility issues and pregnancy-related outcomes and offspring development. The evidence suggests that the increased risk of pregnancy complications and adverse offspring outcomes of PCOS women would be due to the factors involved in the syndrome pathogenesis and the related co-morbidities. A better understanding of the involved mechanisms is still needed and could contribute to a better management of these women and their offspring. This article is categorized under: Reproductive System Diseases > Molecular and Cellular Physiology Reproductive System Diseases > Environmental Factors.

Integrated analysis of multiple microarray studies to identify potential pathogenic gene modules in preeclampsia

BACKGROUND

Preeclampsia is a life-threatening hypertensive disorder during pregnancy, while underlying pathogenesis and its diagnosis are incomplete.

METHODS

In this study, we utilized the Robust Rank Aggregation method to integrate 6 eligible preeclampsia microarray datasets from Gene Expression Omnibus database. We used linear regression to assess the associations between significant differentially expressed genes (DEGs) and blood pressure. Functional annotation, protein-protein interaction, Gene Set Enrichment Analysis (GSEA) and single sample GSEA were employed for investigating underlying pathogenesis in preeclampsia.

RESULTS

We filtered 52 DEGs and further screened for 5 hub genes (leptin, pappalysin 2, endoglin, fms related receptor tyrosine kinase 1, tripartite motif containing 24) that were positively correlated with both systolic blood pressure and diastolic blood pressure. Receiver operating characteristic indicated that hub genes were potential biomarkers for diagnosis and prognosis in preeclampsia. GSEA for single hub gene revealed that they were all closely related to angiogenesis and estrogen response in preeclampsia. Moreover, single sample GSEA showed that the expression levels of 5 hub genes were correlated with those of immune cells in immunologic microenvironment at maternal-fetal interface.

CONCLUSIONS

These findings provide new insights into underlying pathogenesis in preeclampsia; 5 hub genes were identified as biomarkers for diagnosis and prognosis in preeclampsia.

A review of the role of inositols in conditions of insulin dysregulation and in uncomplicated and pathological pregnancy

Inositols, a group of 6-carbon polyols, are highly bioactive molecules derived from diet and endogenous synthesis. Inositols and their derivatives are involved in glucose and lipid metabolism and participate in insulin-signaling, with perturbations in inositol processing being associated with conditions involving insulin resistance, dysglycemia and dyslipidemia such as polycystic ovary syndrome and diabetes. Pregnancy is similarly characterized by substantial and complex changes in glycemic and lipidomic regulation as part of maternal adaptation and is also associated with physiological alterations in inositol processing. Disruptions in maternal adaptation are postulated to have a critical pathophysiological role in pregnancy complications such as gestational diabetes and pre-eclampsia. Inositol supplementation has shown promise as an intervention for the alleviation of symptoms in conditions of insulin resistance and for gestational diabetes prevention. However, the mechanisms behind these affects are not fully understood. In this review, we explore the role of inositols in conditions of insulin dysregulation and in pregnancy, and identify priority areas for research. We particularly examine the role and function of inositols within the maternal-placental-fetal axis in both uncomplicated and pathological pregnancies. We also discuss how inositols may mediate maternal-placental-fetal cross-talk, and regulate fetal growth and development, and suggest that inositols play a vital role in promoting healthy pregnancy.

Exploring strengths and limits of urinary D-chiro inositol phosphoglycans (IPG-P) as a screening test for preeclampsia: A systematic review and meta-analysis

Preeclampsia is a severe complication of human pregnancy as it leads to significant maternal and perinatal mortality and morbidity worldwide. A prompt recognition of women that develop this syndrome can improve clinical management, increase surveillance and, finally, improve outcomes. Different methods (based on history, ultrasound, serum and urinary biomarkers) were proposed a screening tests for this disease but their performance showed limited results. Urinary inositol phosphoglycans P-type (IPG-P) were shown to identify in advance most of the women who will develop preeclampsia in case-control and longitudinal studies, so we undertook a systematic review and meta-analysis of published studies. Seven studies met the entry criteria so were evaluated. All case-control studies showed excellent statistical performances in a quality statistical assessment. The meta-analysis considered three longitudinal, prospective studies that showed high sensitivity and specificity with ranges of 0.82- 0.99 and 0.90-1.00, respectively. Univariate measures of accuracy revealed a positive and negative likelihood ratio respectively of 3.61 (95% CI 1.56-5.67) and -2.35 (95% CI -3.79 to -0.91). By univariate approach, we found a pooled logarithm of diagnostic odds ratio of 6.15 (95% CI 2.64-9.67). A limitation of this analysis is that, although conducted in different settings (UK, Italy, France, South Africa, and Mauritius) and different clinical groups, they were based on a single academic group. According to our findings, IPG-P test showed very encouraging results as a rapid noninvasive screening test for preeclampsia. Further studies are needed to verify and to validate the reported findings.

Preeclampsia and the 20th century: "Le siècle des Lumières"

The authors delineate seven quantum leap forward and, or revolutions having occurred during the 20th century in the understanding of the physiopathology of preeclampsia. First the discovery of the inflatable arm band permitting to measure blood pressure in 1896. Second, the discovery that eclamptic (convulsions), and later "pre"eclamptic (proteinuria) women presented hypertension in 1897 and confirmed in 1903, discovery of the hypertensive disorders of pregnancy. Third, the eight major textbooks published all along the 20th century by delineating risk factors of preeclampsia with the concept of "preeclampsia, disease of primigravidae". Fourth, the discovery in the 1970's that human trophoblast implantation was far deeper than in other mammalian species. Fifth, and a major step forward, description at the end of the 1980's that the maternal syndrome in preeclampsia (glomeruloendotheliosis, HELLP syndrome, eclampsia) could be unified in a global endothelial cell inflammation. Sixth, the epidemiological descriptions in the 1970-1990's that indeed preeclampsia was a disease of first pregnancies at the level of a couple ("primipaternity concept"), leading to an explosion in immunological research in the last decade, beginning in 1998. Seventh and finally, in the search for the "factor X" explaining the vascular inflammation in preeclamptic women (inositol phospho glycans P-type were described in 2000, while soluble Flt-1 and S-endoglins have been clearly predicted since 1997). The majority of the seeds or findings have been grounded or realized in the 20th century. Indeed, for preeclampsia, the 20th century has been le "Siècle des Lumières" (the Enlightments).

Immunological Tolerance, Pregnancy, and Preeclampsia: The Roles of Semen Microbes and the Father

Although it is widely considered, in many cases, to involve two separable stages (poor placentation followed by oxidative stress/inflammation), the precise originating causes of preeclampsia (PE) remain elusive. We have previously brought together some of the considerable evidence that a (dormant) microbial component is commonly a significant part of its etiology. However, apart from recognizing, consistent with this view, that the many inflammatory markers of PE are also increased in infection, we had little to say about immunity, whether innate or adaptive. In addition, we focused on the gut, oral and female urinary tract microbiomes as the main sources of the infection. We here marshall further evidence for an infectious component in PE, focusing on the immunological tolerance characteristic of pregnancy, and the well-established fact that increased exposure to the father's semen assists this immunological tolerance. As well as these benefits, however, semen is not sterile, microbial tolerance mechanisms may exist, and we also review the evidence that semen may be responsible for inoculating the developing conceptus (and maybe the placenta) with microbes, not all of which are benign. It is suggested that when they are not, this may be a significant cause of PE. A variety of epidemiological and other evidence is entirely consistent with this, not least correlations between semen infection, infertility and PE. Our view also leads to a series of other, testable predictions. Overall, we argue for a significant paternal role in the development of PE through microbial infection of the mother via insemination.

New insights into early and late onset subgroups of preeclampsia from longitudinal versus cross-sectional analysis of urinary inositol-phosphoglycan P-Type

Most pre-eclampsia (PE) studies have used cross-sectional data to derive conclusions regarding the pathophysiology of the condition. This has led to the concept that there exists early (<34 weeks) and late-onset (>34 weeks) disease according to gestational age at diagnosis. Survival time models have predicted that if the pregnancy was to continue indefinitely, all women would develop PE. In this study we have performed a longitudinal analysis of the urinary biomarker, inositol phosphoglycan (IPG), in a cohort of women giving birth in Mauritius (n-920). We have analysed the PE data in the traditional cross-sectional manner for n = 77 women who developed PE and also then looked at the longitudinal data for 71/77 of the same women. The data allows us to use longitudinal values to calculate a date of onset (first presence of biomarker in urine) and compare that to date of clinical diagnosis (cross sectional). We find two populations for both analysis consistent with an early and late stage subgroup. The calculated date of onset had subgroups (early and late) at 28.4 ± 0.41 weeks and 35.37 ± 0.26 weeks and for clinical date of diagnosis, 32.3 ± 0.59 weeks and 37.04 ± 0.62 weeks, respectively. The presence of the same biomarker in both subgroups and its ability to predict clinical onset 2-4 weeks prior to clinical diagnosis suggest that both groups may have similar aetiology.

Historical evolution of ideas on eclampsia/preeclampsia: A proposed optimistic view of preeclampsia

Eclampsia (together with epilepsy) being the first disease ever written down since the beginning of writings in mankind 5000 years ago, we will make a brief presentation of the different major steps in comprehension of Pre-eclampsia. 1) 1840. Rayer, description of proteinuria in eclampsia, 2) 1897 Vaquez, discovery of gestational hypertension in eclamptic women, 3) In the 1970's, description of the "double" trophoblastic invasion existing only in humans (Brosens & Pijnenborg,), 4) between the 1970's and the 1990's, description of preeclampsia being a couple disease. The "paternity problem" (and therefore irruption of immunology), 5) at the end of the 1980's, a major step forward: Preeclampsia being a global endothelial cell disease (glomeruloendotheliosis, hepatic or cerebral endotheliosis, HELLP, eclampsia), inflammation (J.Roberts.C Redman, R Taylor), 6) End of the 1990's: Consensus for a distinction between early onset preeclampsia EOP and late onset LOP (34 weeks gestation), EOP being rather a problem of implantation of the trophoblast (and the placenta), LOP being rather a pre-existing maternal problem (obesity, diabetes, coagulopathies etc…). LOP is predominant everywhere on this planet, but enormously predominant in developed countries: 90% of cases. This feature is very different in countries where women have their first child very young (88% of world births), where the fatal EOP (early onset) occurs in more than 30% of cases. 7) What could be the common factor which could explain the maternal global endotheliosis in EOP and LOP? Discussion about the inositol phospho glycans P type.

PKB/Akt and MAPK/ERK phosphorylation is highly induced by inositols: Novel potential insights in endothelial dysfunction in preeclampsia

PKB/Akt and MAP/ERK are intracellular kinases regulating cell survival, proliferation and metabolism and as such hold a strategical role in preeclampsia. In fact intracellular pathways related to immunological alterations, endothelial dysfunction and insulin resistance in preeclampsia converge on these molecules. Inositol second messengers are involved in metabolic and cell signaling pathways and are highly expressed during preeclampsia. To evaluate the pathophysiological significance of this response, the effect of myo-inositol and d-chiro inositol on the activation of PKB/Akt and MAPK/ERK was assessed in human endothelial cells in vitro. Time-course and dose-response analyses of phosphorylation following incubation with inositols showed an approximately 6-fold and 15-fold increase for myo-inositol and d-chiro inositol (p<0.05), respectively. Both inositols promoted a significantly higher PKB/Akt and MAPK/ERK phosphorylation than insulin. Thus, exogenously administered inositols can activate PKB/Akt and MAPK/ERK in human endothelial cells in vitro. The increased production of d-chiro inositol phosphoglycans (IPG-P) during preeclampsia may thus represent a compensatory response, potentially promoting cell survival and metabolism.

Putative Key Role of Inositol Messengers in Endothelial Cells in Preeclampsia

Immunological alterations, endothelial dysfunction, and insulin resistance characterize preeclampsia. Endothelial cells hold the key role in the pathogenesis of this disease. The signaling pathways mediating these biological abnormalities converge on PKB/Akt, an intracellular kinase regulating cell survival, proliferation, and metabolism. Inositol second messengers are involved in metabolic and cell signaling pathways and are highly expressed during preeclampsia. Intracellular action of these molecules is deeply affected by zinc, manganese, and calcium. To evaluate the pathophysiological significance, we present the response of the intracellular pathways of inositol phosphoglycans involved in cellular metabolism and propose a link with the disease.

Second trimester amniotic fluid myo-inositol concentrations in women later developing gestational diabetes mellitus or pregnancy-induced hypertension

OBJECTIVE

To evaluate myo-inositol concentrations in amniotic fluid in women later developing gestational diabetes and hypertension.

METHODS

A retrospective study was carried out with three groups of amniotic fluid samples (15-18 gestational weeks): 30 gestational hypertension pregnancies, 30 gestational diabetes pregnancies, and 30 normal pregnancy.

RESULTS

A significant difference was observed in myo-inositol concentrations between the median gestational diabetes values (124.0 µmol/L, IQR 90.0-162.5) and the control group values (79.0 µmol/L, IQR 62.0-107.5), but also with gestational hypertension median values (79.0 µmol/L, IQR 67.75-92.0) (p < 0.001).

CONCLUSIONS

This study has shown that myo-inositol concentrations in amniotic fluid increased significantly in women later developing gestational diabetes compared to the control group.

Endothelial dysfunction and metabolic syndrome in preeclampsia: an alternative viewpoint

Several clinical and basic science reports have elucidated partial aspects of the pathophysiology of preeclampsia and have led many authors to conclude that different "subtypes" of the disease exist. All these subtypes share the main clinical features of the disease and present additional characteristics that define different clinical phenotypes. Nevertheless, immunological alterations, endothelial dysfunction, and insulin resistance constantly characterize this syndrome. These aspects are intimately related at a molecular level; thus, we propose an alternative approach to explaining biologically the main intracellular processes that occur in preeclampsia and this may yield an insight into the pathogenesis.

Urinary inositol phosphoglycan-P type: near patient test to detect preeclampsia prior to clinical onset of the disease. A study on 416 pregnant Mauritian women

Preeclampsia and eclampsia account for major pregnancy complications in Mauritius, an emerging country (maternal mortality rate of 60 per 100,000 deliveries). This prospective longitudinal study was carried out in the main regional hospital in the north of the island, to measure inositol phosphoglycan-P type (IPG-P) in the urine of pregnant women (using an ELISA-based assay). Women had approximately 10 prenatal visits per pregnancy and a complete follow-up in this same referral centre after the first trimester of pregnancy. Urine samples were collected every 1-4 weeks in all women. In a cohort of 416 patients, preeclampsia (PE) was diagnosed in 34 women. In established PE (hypertension and proteinuria), the assay as a diagnostic test showed a positive likelihood ratio of 18.73, a negligible negative likelihood ratio with area under the curve (AUC) of 0.99, sensitivity of 96.7%, specificity of 94.8% and remained negative in control women (n=312), women with gestational hypertension (without proteinuria (n=56), and gestational diabetic mothers (n=14). Moreover, as a predictive screening test two weeks before the diagnosis of PE, the assay showed sensitivity of 84.2% and specificity of 83.6%. Detection of urinary inositol phosphoglycan-P type in pregnant women can be a useful confirmatory marker of PE, as well as a predictive marker, two weeks before the onset of the disease.

Protection against the synaptic targeting and toxicity of Alzheimer's-associated Aβ oligomers by insulin mimetic chiro-inositols

Alzheimer's disease (AD) is a progressive dementia that correlates highly with synapse loss. This loss appears due to the synaptic accumulation of toxic Aβ oligomers (ADDLs), which damages synapse structure and function. Although it has been reported that oligomer binding and toxicity can be prevented by stimulation of neuronal insulin signaling with PPARγ agonists, these agonists have problematic side effects. We therefore investigated the therapeutic potential of chiro-inositols, insulin-sensitizing compounds safe for human consumption. Chiro-inositols have been studied extensively for treatment of diseases associated with peripheral insulin resistance, but their insulin mimetic function in memory-relevant central nervous system (CNS) cells is unknown. Here we demonstrate that mature cultures of hippocampal neurons respond to d-chiro-inositol (DCI), pinitol (3-O-methyl DCI), and the inositol glycan INS-2 (pinitol β-1-4 galactosamine) with increased phosphorylation in key upstream components in the insulin-signaling pathway (insulin receptor, insulin receptor substrate-1, and Akt). Consistent with insulin stimulation, DCI treatment promotes rapid withdrawal of dendritic insulin receptors. With respect to neuroprotection, DCI greatly enhances the ability of insulin to prevent ADDL-induced synapse damage (EC(50) of 90 nM). The mechanism comprises inhibition of oligomer binding at synapses and requires insulin/IGF signaling. DCI showed no effects on Aβ oligomerization. We propose that inositol glycans and DCI, a compound already established as safe for human consumption, have potential as AD therapeutics by protecting CNS synapses against Aβ oligomers through their insulin mimetic activity.

Placental expression of D-chiro-inositol phosphoglycans in preeclampsia

Abnormalities in glucose metabolism linked to D-chiro-inostol phosphoglycans (IPGs) have been described in human placentas of preeclamptic women. In this study, a semi-quantitative approach to assess the histological assessment of IPGs revealed no significant differences between early and late onset preeclampsia and gestational age matched controls. However, there was a tendency towards higher values in early onset preeclampsia for villous stroma and placental vessels. Moreover, in control cases staining of plasma in placental vessels was present only in one part of vessels of mature intermediate villi while in preeclamptic specimens all placental vessels showed a similar staining. The tendencies of more staining in villous stroma associated with a differential staining of placental vessels only in preeclamptic specimens support a vectoral movement of D-chiro-inositol phosphoglycans from the fetus to the placenta.

Insulin stimulation of Akt/PKB phosphorylation in the placenta of preeclampsia patients

CONTEXT AND OBJECTIVE

Preeclampsia is a multi-systemic disease and one of the most frequent severe health problems during pregnancy. Binding of insulin triggers phosphorylation and activates cytoplasmic substrates such as phosphatidylinositol 3 kinase (PI3K). Phosphorylation of membrane phosphoinositide 2 (PIP2) to phosphoinositide 3 (PIP3) by PI3K starts Akt/PKB activation. Defects in phosphorylation of the insulin receptor and its substrates have an important role in insulin resistance. Studies have shown that insulin resistance is associated with preeclampsia and its pathophysiology. The aim here was to investigate insulin stimulation of the Akt/PKB pathway in the placenta, in normal and preeclampsia parturients.

DESIGN AND SETTING

Cross-sectional study in a tertiary public university hospital.

METHODS

Placentas were collected from 12 normal and 12 preeclampsia patients. These were stimulated and analyzed using Western blot to quantify the Akt/PKB phosphorylation.

RESULTS

The insulin stimulation was confirmed through comparing the stimulated group (1.14 ± 0.10) with the non-stimulated group (0.91 ± 0.08; P < 0.001). The phosphorylation of Akt/PKB did not differ between the placenta of the normal patients (1.26 ± 0.16) and those of the preeclampsia patients (1.01 ± 0.11; P = 0.237).

CONCLUSIONS

In vitro insulin stimulation of the human placenta has been well established. There was no difference in Akt/PKB phosphorylation, after stimulation with insulin, between placentas of normal and preeclampsia patients. Nevertheless, it cannot be ruled out that the Akt/PKB signaling pathway may have a role in the pathophysiology of preeclampsia, since the substrates of Akt/PKB still need to be investigated.

Endometrial secretions: creating a stimulatory microenvironment within the human early placenta and implications for the aetiopathogenesis of preeclampsia

Endometrial glands represent an important source of nutrients for the conceptus during the first trimester. Their secretions are enriched with carbohydrates, and glycogen accumulates within the syncytiotrophoblast of the placenta. It has been assumed that fetal and placental metabolism follow adult pathways, although it is now appreciated that early development occurs in a low-oxygen environment. In past decades, a novel family of putative insulin mediators, inositol phosphoglycans (IPGs), was discovered. These molecules act as allosteric activators and/or inhibitors of enzymes and transduction proteins involved in the control of cell signalling and metabolic pathways, and determine the specificity of responses after activation of the insulin receptor. One member, IPG P-type, activates pyruvate dehydrogenase phosphatase (PDH-Pase), glycogen synthase phosphatase, and glycerol-3-phosphate acyltransferase. Activation of key phosphatases play a major role in the regulation of glucose disposal by oxidative metabolism via PDH, and the non-oxidative storage by glycogen synthesis, both pathways classically known to be regulated by insulin. High concentrations of IPG P-type in amniotic fluid suggest a role in the regulation of carbohydrate metabolism in the fetal-placental unit. Glycogen accumulation in the syncytiotrophoblast also occurs in preeclamptic pregnancies, and is consistently associated with higher placental levels of IPG P-type. Here, we explore the relationship between nutrients provided by the endometrial glands during early pregnancy, IPG P-type and fetal metabolic requirements. We also discuss whether a disconnect between the placental/fetal metabolic state and oxygen tension could lead to a preeclamptic-type syndrome via leakage of Warburg/IPG mediators into the maternal circulation.

Age-related changes in the response of rat adipocytes to insulin: evidence for a critical role for inositol phosphoglycans and cAMP

Adipose tissue plays a pivotal role in ageing and longevity; many studies, both human and animal, have focussed on the effects of food limitation. Here we present a new model based on striking differences between two 'normal' inbred strains of albino Wistar rats the Charles River (CR) and Harlan Olac (HO) that have marked differences in age-related accumulation of fat and insulin-stimulated rates of glucose incorporation into lipid in the epididymal fat pads (EFP). The incorporation [U-(14)C]glucose into lipid by adipocytes showed that the CR group had a twofold higher basal rate of lipogenesis and a greater response to insulin in vitro, exceptionally, adipocytes from CR group maintained the high response to insulin to late adulthood while retaining the lower EFP weight/100 g body weight. Inositol phosphoglycan A-type (IPG-A), a putative insulin second messenger, was 3.5-fold higher and cAMP significantly lower per EFP in the CR versus HO groups. Plasma insulin levels were similar and plasma leptin higher in CR versus HO groups. The anomaly of a higher rate of lipogenesis and response to insulin and lower EFP weight in the CR group is interpreted as the resultant effect of a faster turnover of lipid and stimulating effect of leptin in raising fatty acid oxidation by muscle, potentially key to the lower accumulation of visceral fat. The metabolic profile of the CR strain provides a template that could be central to therapies that may lead to the lowering of both adipose and non-adipocyte lipid accumulation in humans in ageing.

Inositol phosphoglycan putative insulin mediator in human amniotic fluid

BACKGROUND

Many hormones such as insulin, insulin-like growth factors, and the glucocorticoids are involved in regulating fetal growth. Inositol phosphoglycans (IPGs), a family of putative second messengers of insulin, are reported to exert several of insulin's metabolic effects.

METHODS

A prospective cross-sectional study was carried out to investigate IPG P-type (P-IPG) in human amniotic fluid and in adult urine under physiological conditions. An amniotic fluid sample was taken from 78 women undergoing early amniocentesis and a mid-stream urine specimen was collected from 109 healthy pregnant and 66 non-pregnant women. All samples were assessed using a polyclonal antibody-based ELISA.

RESULTS

The P-IPG content was a thousand times higher in the amniotic fluid than in the urine (p < 0.0001). Urinary specimens showed a four-fold higher P-IPG content during pregnancy than in healthy non-pregnant women (p < 0.001).

CONCLUSIONS

Under physiological conditions, human amniotic fluid was found to be enriched in P-IPG compared with maternal urine, suggesting a possible fetal origin. Therefore, IPGs may play a role in insulin sensitivity and fetal growth and, perhaps, be involved in some of its abnormalities such as macrosomia and intrauterine growth restriction.

Insight into the role of inositol phosphoglycans in insulin response and the regulation of glucose and lipid metabolism illustrated by the response of adipocytes from two strains of rats

Differences in biochemical and hormone profiles between two strains of rats provide insights into the relationships between insulin response, inositol phosphoglycans and lipid metabolism in adipose tissue. The results suggest the apparent anomaly of a higher rate of lipogenesis and response to insulin with a lower fat pad weight in the Charles River vs. Harlan Olac group relates to: (i) enzyme pre-programming with IPG-A, (ii) faster turnover of lipid, (iii) effects of leptin and cAMP.

Inositol phosphoglycan P-type in healthy and preeclamptic pregnancies

An association between inositol phosphoglycan P-type (P-IPG) and preeclampsia has been demonstrated over recent years. This molecule can mediate many of the metabolic and growth promoting effects of insulin. Dysregulation of the mediator family is associated with insulin resistance. An increased concentration of P-IPG has been reported in preeclamptic placenta, although its precursor (GPI) was undetectable in those placental samples. Insulin administration, that induces P-IPG release in normal human placenta, was shown not to cause production/release of the mediator from preeclamptic placental tissue as a consequence of a disturbed insulin signalling. Amniotic fluid is enriched of this mediator, with further increase during preeclampsia. We have found that the fetus released increasing amounts of P-IPG in the urine between 13 and 18 weeks of gestation, reaching a plateau beyond 20 weeks. Cord blood of infants of preeclamptic mothers showed an increased content of soluble P-IPG compared to controls and to the mother.

Preeclampsia, insulin signalling and immunological dysfunction: a fetal, maternal or placental disorder?

An inappropriate glycogen accumulation in preeclamptic placentas was described as secondary to biochemical alterations. Insulin resistance is widely accepted to be associated with preeclampsia, although its basis remain unclear. A family of putative insulin mediators, namely inositol phosphoglycans, were described to exert many insulin-like effects on lipid and glucose metabolism. A definite association between the P-type mediator (P-IPG) and preeclampsia was reported, being increased in placenta, urine, amniotic fluid and cord blood from human preeclamptic pregnancies. A strong link exists between insulin resistance and inflammation. Clear features of insulin resistance and systemic inflammatory activation were described in preeclampsia. It may be a consequence of the immunological dysfunction that occurs in preeclampsia that is temporized during sperm exposure and co-habitation which confuses the maternal immune network to perceive 'danger'. The over-expression of P-IPG during preeclampsia may be a counter-regulatory mechanism to insulin resistance since these molecules mimic insulin action. Besides, the lipidic form of P-IPG was reported to be similar to endotoxins, and may represent the 'danger signa'. We propose here a novel working theory on insulin resistance and preeclampsia.

Urinary excretion of inositol phosphoglycan P-type in gestational diabetes mellitus

OBJECTIVE

The mechanisms underlying insulin resistance during normal pregnancy, and its further exacerbation in pregnancies complicated by gestational diabetes mellitus (GDM), are generally unknown. Inositolphosphoglycan P-type (P-IPG), a putative second messenger of insulin, correlates with the degree of insulin resistance in diabetic subjects. An increase during normal pregnancy, in maternal and fetal compartments, has recently been reported.

METHODS

A cross-sectional study was carried out in 48 women with GDM and 23 healthy pregnant women. Urinary levels of P-IPG were assessed spectrophotometrically by the activation of pyruvate dehydrogenase phosphatase in urinary specimens and correlated with clinical parameters.

RESULTS

Urinary excretion of P-IPG was higher in GDM than in control women (312.1 +/- 151.0 vs. 210.6 +/- 82.7 nmol NADH/min/mg creatinine, P < 0.01) with values increasing throughout pregnancy in control subjects (r2 = 0.34, P < 0.01). P-IPG correlated with blood glucose levels (r(2) = 0.39, P < 0.01 for postprandial glycaemia and r2 = 0.18 P < 0.01 for mean glycaemia) and birthweight in the diabetic group (r2 = 0.14, P < 0.01).

CONCLUSIONS

Increased P-IPG urinary excretion occurs in GDM and positively correlates with blood glucose levels. P-IPG may play a role in maternal glycaemic control and, possibly, fetal growth in GDM.

Expression of galectin-1, -3 (gal-1, gal-3) and the Thomsen-Friedenreich (TF) antigen in normal, IUGR, preeclamptic and HELLP placentas

BACKGROUND

Galectin-1 (gal-1) and galectin-3 (gal-3), which are members of the mammalian beta-galactoside-binding proteins, recognise preferentially (Galbeta1-4GlcNAc) sequences of several cell surface oligosaccharides. In addition, gal-1 also binds to the Thomsen-Friedenreich (TF) antigen (Galbeta1-3GalNAc-).

MATERIALS AND METHODS

Slides of frozen and paraffin-embedded placental tissue of patients with fetal intrauterine growth retardation (IUGR), preeclampsia, haemolysis, elevated liver enzymes, low platelets (HELLP) and normal term placentas were incubated with monoclonal and polyclonal antibodies against gal-1, gal-3 and TF. Staining reaction was performed with the avidin-biotinylated peroxidase complex (ABC) reagent. The intensity of the immunohistochemical reaction on the slides was analysed using a semi-quantitative score. The identity of galectin-expressing cells was analysed by using a double immunofluorescence method.

RESULTS

We demonstrated immunohistochemically that the expression of gal-1 and gal-3 on the extravillous trophoblast (EVT) is significantly up-regulated in preeclamptic and HELLP placentas and unchanged compared with normal controls in IUGR placentas. The expression of the TF antigen is significantly up-regulated in IUGR and preeclamptic extravillous trophoblast cells and unchanged in HELLP placentas compared with normal controls. In addition, the expression of gal-1 is significantly up-regulated in the decidual tissue of preeclamptic placentas and in the villous trophoblast tissue of HELLP placentas.

CONCLUSION

Our data showed that gal-1, gal-3 and TF were up-regulated on the membrane of EVT in preeclamptic placentas. In addition, the expression of gal-1 is significantly up-regulated in decidual tissue of preeclamptic placentas and villous trophoblast tissue of HELLP placentas. Taking into consideration the results of this study, we speculate that expression of both galectins and TF on the membrane of preeclamptic EVT and up-regulation of gal-1 in preeclamptic decidual cells may at least in part compensate for the apoptotic effects of maternal immune cells.

Inositol Phosphoglycan P-Type in Preeclampsia

A state of insulin resistance has been demonstrated in active preeclampsia, and women with clinical evidence of insulin resistance are at higher risk to develop this syndrome during pregnancy. Recently, inositol phosphoglycan P-type, a putative second messenger of insulin action, has been implicated in the pathophysiology of preeclampsia and is increased in the placenta, amniotic fluid, and maternal urine of preeclamptic women compared with normal pregnant women. We report here a case–control study to assess the potential of urinary levels of inositol phosphoglycan P-type as a screening test for preeclampsia. Twenty-seven preeclamptic women and 47 healthy pregnant women were recruited. A polyclonal antibody-based ELISA was developed to detect levels of inositol phosphoglycan P-type in urine. Its content in urinary specimens was found to be 30-fold higher in preeclamptic subjects than control subjects (329.1±21.8 versus 9.2±1.5; P <0.001), with a higher level in all of the preeclamptic cases. For 6 women who developed preeclampsia, >1 gestational date sample of urine was available, and retrospective analysis showed a significant time-related increase of the urinary level of inositol phosphoglycan P-type ≤7 weeks before clinical diagnosis of preeclampsia. Urinary level of inositol phosphoglycan P-type increased after diagnosis indicating a possible pathophysiological threshold level and steeply decreased after delivery.

P-type inositol phosphoglycans in serum and amniotic fluid in active pre-eclampsia

OBJECTIVES

Abnormal secretion of P-type inositol phosphoglycans (IPG-P) has been described in maternal urine of pre-eclamptic women. The aim of this study was to determine the origin of production of IPG-P. We examined the IPG-P content of maternal and fetal serum, maternal urine and amniotic fluid in both normal pregnancy and pre-eclampsia.

DESIGN

Established extraction and bioactivity assay techniques were used to compare total IPG-P levels in serum samples, and a polyclonal-antibody-based ELISA to assay the amniotic fluid and urine samples in matched pairs of women.

SUBJECTS

Eleven women with pre-eclampsia requiring caesarean section (subjects), 11 pregnant women requiring elective caesarean section for reasons other than pre-eclampsia (controls).

RESULTS

Our data confirm the abnormal level of IPG-P in maternal urine during pre-eclampsia. Moreover, IPG-P levels were higher in umbilical sera than in maternal sera samples. Amniotic fluid as well as urine ELISA results were significantly higher in the pre-eclamptic group compared with normal controls. Total IPG-P bioactivity in serum did not vary between serum compartments in normal pregnancy. Uterine vein IPG-P levels were lower in pre-eclampsia when compared with normal pregnancy. A possible correlation was observed between urine and amniotic fluid levels in normal women. No correlation was observed between measured blood levels and those in urine and amniotic fluid.

CONCLUSIONS

It is hypothesized that steady state equilibrium of IPG-P in serum in normal pregnancy is disrupted in pre-eclampsia. Additionally, an abnormal IPG-P sub-fraction, detectable in urine and amniotic fluid, may be present and involved in the pathophysiology of the syndrome, although sites of production of this abnormal form remain unclear.

Insulin resistance in human preeclamptic placenta is mediated by serine phosphorylation of insulin receptor substrate-1 and -2

CONTEXT

Preeclampsia is a severe complication of human pregnancy often associated with maternal risk factors. Insulin resistance represents a major risk for developing preeclampsia during pregnancy.

OBJECTIVE

A putative second messenger of insulin, inositol phosphoglycan P type (P-IPG), was previously shown to be highly increased during active preeclampsia. Its association with insulin resistance was investigated.

DESIGN AND SETTING

A cross-sectional study was carried out in a referral center.

PATIENTS

Nine preeclamptic (PE) and 18 healthy women were recruited and matched for maternal age, body mass index, parity, and ethnicity in a 1:2 ratio. Placental specimens were collected immediately after delivery.

INTERVENTION

Placental tissue was incubated with insulin and P-IPG production assessed. Insulin signaling proteins were subsequently studied by immunoblotting.

RESULTS

P-IPG extracted from human term placentas upon incubation with insulin was found to be far lower in those with preeclampsia than controls (P < 0.001). Immunoblotting studies revealed serine phosphorylation of insulin receptor substrate-1 and -2 in PE placentas (P < 0.001) with downstream impairment of insulin signaling. The activation of the p85 regulatory subunit of phosphatidylinositol 3- kinase was markedly decreased in PE samples (P < 0.001).

CONCLUSIONS

These findings highlight the importance of P-IPG in active preeclampsia and demonstrate a substantially different response to the insulin stimulus of human PE placentas. Acquired alterations in activation of proteins involved in insulin signaling may play a role in the complex pathogenesis of preeclampsia, probably as a consequence of the immunological dysfunction that occurs in this syndrome. These results seem to confirm an insulin-resistant state in PE placenta and shed a different light on its role in the pathogenesis of this disease with potential therapeutic implications.

Role of Lipid Peroxidation in the Epidemiology and Prevention of Breast Cancer

We have recently proposed a common mechanistic pathway by which obesity and hypertension lead to increased renal cell cancer risk. Our hypothesis posits lipid peroxidation, which is a principal mechanism in rodent renal carcinogenesis, as an intermediate step that leads to a final common pathway shared by numerous observed risks (including obesity, hypertension, smoking, oophorectomy/hysterectomy, parity, preeclampsia, diabetes, and analgesics) or protective factors (including oral contraceptive use and alcohol) for renal cell cancer [Cancer Causes Control 2002;13:287-93]. During this exercise, we have noticed how certain risk factors for renal cell carcinoma are protective for breast cancer and how certain protective factors for renal cell carcinoma increase risk for breast cancer. Parity and oophorectomy, for example, are positively associated with renal cell carcinoma but are negatively associated with breast cancer. Similarly, obesity and hypertension are positively associated with renal cell carcinoma, but obesity is negatively associated with breast cancer in premenopausal women and hypertension during pregnancy is negatively associated with breast cancer. Furthermore, alcohol intake, negatively associated with renal cell carcinoma, is also positively associated with breast cancer. We propose here the possibility that lipid peroxidation may represent a protective mechanism in breast cancer. Although this runs counter to the conventional view that lipid peroxidation is a process that is harmful and carcinogenic, we present here the chemical and biological rationale, based on epidemiologic and biochemical data, which may deserve further consideration and investigation.

Improvement of glucose homeostasis in obese diabetic db/db mice given Plasmodium yoelii glycosylphosphatidylinositols

We have previously reported that infection with Plasmodium yoelii, Plasmodium chabaudi, or injection of extracts from malaria-parasitized red blood cells induces hypoglycemia in normal mice and normalizes the hyperglycemia in streptozotocin (STZ)-diabetic mice. P yoelii glycosylphosphatidylinositols (GPIs) were extracted in chloroform:methanol:water (CMW) (10:10:3), purified by high-performance thin layer chromatography (HPTLC) and tested for their insulin-mimetic activities. The effects of P yoelii GPIs on blood glucose were investigated in insulin-resistant C57BL/ks-db/db diabetic mice. A single intravenous injection of GPIs (9 and 30 nmol/mouse) induced a significant dose-related decrease in blood glucose (P < .001), but insignificantly increased plasma insulin concentrations. A single oral dose of 2.7 micromol GPIs per db/db mouse significantly lowered blood glucose (P < .01). P yoelii GPIs in vitro (0.062 to 1 micromol/L) significantly stimulated lipogenesis in rat adipocytes in a dose-dependent manner both in the presence and absence of 10(-8) mol/L insulin (P < .01). P yoelii GPIs stimulated pyruvate dehydrogenase phosphatase (PDH-Pase) and inhibited both cyclic adenosine monophosphate (cAMP)-dependent protein kinase A and glucose-6-phosphatase (G6Pase). P yoelii GPIs had no effect on the activity of the gluconeogenic enzymes fructose-1,6-bisphosphatase (FBPase) and phosphoenolpyruvate carboxykinase (PEPCK). This is the first report of the hypoglycemic effect of P yoelii GPIs in murine models of type 2 diabetes. In conclusion, P yoelii GPIs demonstrated acute antidiabetic effects in db/db mice and in vitro. We suggest that P yoelii GPIs, when fully characterized, may provide structural information for the synthesis of new drugs for the management of diabetes.

DNA microarrays detect the expression of apoptosis-related genes in preeclamptic placentas

AIMS

To investigate the expression of apoptosis-related genes in preeclamptic placentas and the possible mechanism of the regulation process.

METHODS

Complementary DNA microarrays were employed to compare gene expression profiles of five preeclamptic and five normal placentas.

RESULTS

Among the 368 genes detected over 35% showed an over 2-fold difference of expression between preeclamptic placentas and normal placentas. Many genes involved in cell cycle or apoptosis were more highly expressed in preeclamptic placentas than in normal placentas. The expression of many immune-activation genes in preeclamptic placentas was also higher than that in normal placentas. Additionally, many cytokine receptor/kinase genes were also induced in preeclamptic placentas.

CONCLUSIONS

The change in expression of cell apoptosis-related genes in placentas might be involved in the pathogenesis of preeclampsia, while the activation of the immune system might be one cause of this change.

Placental GPI-PLD is of maternal origin and its GPI substrate is absent from placentae of pregnancies associated with pre-eclampsia

Pre-eclampsia (PE) is a disorder affecting 5-10% of all pregnancies and is characterised by abnormal trophoblast invasion, maternal endothelial cell dysfunction and a systemic maternal response. A unifying factor responsible for eliciting these effects remains unknown. However, levels of the autocrine insulin mediators, inositolphosphoglycans (IPG), are elevated 3-fold in pre-eclamptic placentae compared with controls and are also elevated 3-fold in maternal urine of pre-eclamptic women, suggesting an abnormal paracrine role of the mediator in the systemic maternal response. At the placental level, IPGs are metabolic second messengers capable of eliciting some of the characteristic features of PE, such as the 10-fold increase in glycogen synthesis and 16-fold increase in the activity of the IPG-dependent enzyme glycogen synthase. IPGs are derived from their lipidic precursors, the glycosylphosphatidylinositols (GPI), in membrane associated caveolae by the action of a GPI-specific phospholipase D whose activity is regulated by its membrane microenvironment. We show that the lipidic GPI precursor was detected in total placental membrane and microvillous membrane from normal placentae. The presence of GPI could not be detected in PE placentae, suggesting that the GPI/IPG signalling system is dysregulated in this disorder. Equivalent amounts of a proteolytically-cleaved 50 kDa GPI-PLD protein is detected in both normal and PE placentae. However, GPI-PLD mRNA is absent, suggesting a mechanism of uptake from maternal serum. Since GPI-PLD, whose presence is required for hydrolysis of GPI and release of free IPG, is detectable with equal activity in both normal and PE placentae, we postulate that dysregulation of the tubular caveolar structure of the microvilli in pre-eclamptic placentae provides an environment which promotes the unregulated hydrolysis of GPI in this disorder.

Possible involvement of inositol phosphoglycan-P in human parturition

Preterm labour is a major cause of neonatal morbidity and mortality but the pathophysiology that underlies preterm labour is unknown. Inositolphosphoglycans (IPGs) comprise a ubiquitous family of putative carbohydrate second messengers and they have been linked to the pathogenesis of various conditions, including diabetes and pre-eclampsia. Studying IPG-P levels in normal and pre-eclamptic pregnancies, we noticed a constant rise of urinary IPG-P levels in all women at the time of delivery. A prospective pilot study of urinary IPG-P levels in 23 non-labouring and labouring women with uncomplicated pregnancies has, therefore, been performed. Levels of urinary IPG-P were significantly higher in labour than in the non-labouring group (P<0.0001). These higher levels have been found in both spontaneous and induced labour. The clinical significance of this observation with particular reference to the onset of labour itself is discussed.

Interest in preeclampsia for researchers in reproduction

Gestational hypertension/preeclampsia, is a major disease of human reproduction, with 10% of human births being affected. It is due to the failure of extravillous cytotrophoblast to invade the maternal uterine spiral arteries to a sufficient depth at the second physiological invasion around the 14-16th week of gestation, inducing poor vascular exchanges between the mother and the placenta. The rise of blood pressure in the human mother is then a compensatory mechanism to increase the exchanges and try to save the fetus from poor supplies. Indeed, it is only in the late 1970s that a puzzling phenomenon has been described: in human pregnancy, in contrast with other mammals, implantation of the embryo occurs by two physiological invasions of the cytotrophoblast inside the uterine wall: (a) at the beginning of pregnancy after fecundation (like all mammals); (b) then follows an apparent long pause (6-8 weeks) and (c) late at the end of first trimester (14-16th week) of gestation, a second very deep (1/3 of the uterine wall) invasion. This two-wave physiological endovascular trophoblast invasion represents a remarkable immunological placental-maternal interaction. Moreover, preeclampsia which has been considered as 'the disease of primigravidae' during all the XXth century may be in fact associated with new paternity especially in couples conceiving very shortly after the beginning of their sexual relationship. 'Primipaternity', rather than primigravidity, is probably the leading cause of preeclampsia. Comprehension in the near future of the physiological immunological tolerance in normal pregnancies and immunological rejection (preeclampsia) of the second trophoblastic invasion will give the biological clue of this puzzling disease, real plague of human reproduction.

Prostaglandylinositol cyclic phosphate (cPIP): a novel second messenger of insulin action. Comparative analysis of two kinds of "insulin mediators"

Insulin induces a broad spectrum of effects over a wide time interval. It also stimulates the phosphorylation of some cellular proteins, while decreasing the state of phosphorylation of others. These observations indicate the presence of different, but not necessarily mutually exclusive, pathways of insulin action. One well-known pathway represents a phosphorylation cascade initiated by the tyrosine kinase activity of the insulin receptor followed by involvement of different MAP-kinases. Another pathway suggests the existence of low molecular weight insulin mediators whose synthesis and/or release is initiated by insulin. Comparable analysis of two kinds of insulin mediators, namely inositolphosphoglycans and prostaglandylinositol cyclic phosphate (cPIP), has been carried out. It has been shown that the expression of a number of enzymes, such as phospholipase A(2), phospholipase C, cyclo-oxygenase and IRS-1-like enzyme, could regulate the biosynthesis of cPIP in both normal and diabetes-related conditions. Data on the activity of a key enzyme of cPIP biosynthesis termed cPIP synthase (IRS-1-like enzyme) in various monkey tissues before and twice during an euglycemic hyperinsulinemic clamp have been presented. It has been concluded that in vivo insulin increases cPIP synthase activity in both liver and subcutaneous adipose tissue of lean normal monkeys. It has been also suggested that abnormal production of cPIP could be related to several pathologies including glucocorticoid-induced insulin resistance and diabetic embryopathy. Further studies on cPIP and other types of insulin mediators are necessary to aid our understanding of insulin action.

Elevation of both maternal and fetal extracellular circulating deoxyribonucleic acid concentrations in the plasma of pregnant women with preeclampsia

OBJECTIVE

Elevated amounts of circulating fetal deoxyribonucleic acid in maternal plasma have recently been detected in pregnancies complicated by preeclampsia. We attempted to confirm this finding and simultaneously examined the quantity of maternal circulating deoxyribonucleic acid.

STUDY DESIGN

Circulating deoxyribonucleic acid was measured by realtime quantitative polymerase chain reaction in plasma samples obtained from 44 women with preeclampsia and a matched cohort of 53 normotensive pregnant women.

RESULTS

We confirmed that circulating fetal deoxyribonucleic acid levels were significantly elevated in pregnancies complicated by preeclampsia (3194.6 vs 332.8 copies/mL; P < .001). We also showed for the first time that circulating maternal deoxyribonucleic acid levels are also elevated (219,023.9 vs 20,235.8 copies/mL; P < .001). The increases in these deoxyribonucleic acid levels corresponded to the severity of the disorder, and values were correlated with each other in pregnancies complicated by preeclampsia (r = 0.556; P < .001) but not normotensive pregnancies (r = 0.046; P = .747).

CONCLUSION

The releases of both free fetal and maternal deoxyribonucleic acid were found to be affected in preeclampsia.