Akt/mTOR Role in Human Foetoplacental Vascular Insulin Resistance in Diseases of Pregnancy

Classification of preeclampsia according to molecular clusters with the goal of achieving personalized prevention

The prevention of pre-eclampsia is difficult due to the syndromic nature and multiple underlying mechanisms of this severe complication of pregnancy. The current clinical distinction between early- and late-onset disease, although clinically useful, does not reflect the true nature and complexity of the pathologic processes leading to pre-eclampsia. The current gaps in knowledge on the heterogeneous molecular pathways of this syndrome and the lack of adequate, specific diagnostic methods are major obstacles to early screening and tailored preventive strategies. The development of novel diagnostic tools for detecting the activation of the identified disease pathways would enable early, accurate screening and personalized preventive therapies. We implemented a holistic approach that includes the utilization of different proteomic profiling methods of maternal plasma samples collected from various ethnic populations and the application of systems biology analysis to plasma proteomic, maternal demographic, clinical characteristic, and placental histopathologic data. This approach enabled the identification of four molecular subclasses of pre-eclampsia in which distinct and shared disease mechanisms are activated. The current review summarizes the results and conclusions from these studies and the research and clinical implications of our findings.

How does exosome cause diabetes?

Exosomes are extracellular vesicles that are widely distributed in multiple cell types and circulating body fluids. They have a specific effect on the target cells by releasing different vesicle contents. They have recently been recognized as important means of intercellular communication, being involved, for example, in the development of diabetes by increasing β-cell apoptosis, activating autoimmunity, and regulating cytokines to affect islet β-cell function and insulin sensitivity. An in-depth study of the role of exosome in the pathogenesis of diabetes may therefore provide a novel means of diagnosing and treating diabetes. In this review, we detail how exosome is involved in the development of diabetes.

Consequences of the exposome to gestational diabetes mellitus

The exposome is the cumulative measure of environmental influences and associated biological responses throughout the lifespan, including those from the environment, diet, behaviour, and endogenous processes. The exposome concept and the 2030 Agenda for the Sustainable Development Goals (SDGs) from the United Nations are the basis for understanding the aetiology and consequences of non-communicable diseases, including gestational diabetes mellitus (GDM). Pregnancy may be developed in an environment with adverse factors part of the immediate internal medium for fetus development and the external medium to which the pregnant woman is exposed. The placenta is the interface between maternal and fetal compartments and acts as a protective barrier or easing agent to transfer exposome from mother to fetus. Under and over-nutrition in utero, exposure to adverse environmental pollutants such as heavy metals, endocrine-disrupting chemicals, pesticides, drugs, pharmaceuticals, lifestyle, air pollutants, and tobacco smoke plays a determinant role in the development of GDM. This phenomenon is worsened by metabolic stress postnatally, such as obesity which increases the risk of GDM and other diseases. Clinical risk factors for GDM development include its aetiology. It is proposed that knowledge-based interventions to change the potential interdependent ecto-exposome and endo-exposome could avoid the occurrence and consequences of GDM.

Molecular subclasses of preeclampsia characterized by a longitudinal maternal proteomics study: distinct biomarkers, disease pathways and options for prevention

OBJECTIVES

The heterogeneous nature of preeclampsia is a major obstacle to early screening and prevention, and a molecular taxonomy of disease is needed. We have previously identified four subclasses of preeclampsia based on first-trimester plasma proteomic profiles. Herein, we expanded this approach by using a more comprehensive panel of proteins profiled in longitudinal samples.

METHODS

Proteomic data collected longitudinally from plasma samples of women who developed preeclampsia (n=109) and of controls (n=90) were available from our previous report on 1,125 proteins. Consensus clustering was performed to identify subgroups of patients with preeclampsia based on data from five gestational-age intervals by using select interval-specific features. Demographic, clinical, and proteomic differences among clusters were determined. Differentially abundant proteins were used to identify cluster-specific perturbed KEGG pathways.

RESULTS

Four molecular clusters with different clinical phenotypes were discovered by longitudinal proteomic profiling. Cluster 1 involves metabolic and prothrombotic changes with high rates of early-onset preeclampsia and small-for-gestational-age neonates; Cluster 2 includes maternal anti-fetal rejection mechanisms and recurrent preeclampsia cases; Cluster 3 is associated with extracellular matrix regulation and comprises cases of mostly mild, late-onset preeclampsia; and Cluster 4 is characterized by angiogenic imbalance and a high prevalence of early-onset disease.

CONCLUSIONS

This study is an independent validation and further refining of molecular subclasses of preeclampsia identified by a different proteomic platform and study population. The results lay the groundwork for novel diagnostic and personalized tools of prevention.

Prospecting of exosomal-miRNA signatures as prognostic marker for gestational diabetes mellitus and other adverse pregnancy outcomes

Exosomal microRNA (ExomiRs) serves as potential cargo molecules responsible for post-translation of gene expression and intracellular communication playing a vital role in acting as clinically relevant prognostic biomarkers for identifying pregnancy-associated complications in patients. ExomiRs are associated with Gestational Diabetes Mellitus (GDM) as potential targets for understanding the pathophysiology of beta-cell dysfunction. ExomiRs (ExomiR 122, ExomiR 16-5p, ExomiR 215-5p, ExomiR 450b-3p, ExomiR 122-5p) aid to act as biomarkers and regulate the progression of diabetes and its related complication. These ExomiRshave been reported to interfere with the regulation of various genes such as ZEB2, IRS1, IRS2, GLUT1, GLUT4, etc. and inhibition of several pathways like PI3K/AKT, Wnt, and mTOR signaling pathways leading to the modulation in the development of GDM affecting the clinical and pathological features of women. These ExomiRs have also been associated with other pregnancy-associated complications, including preeclampsia, hypothyroidism, pregnancy loss, and ectopic pregnancies. On the other hand, overexpression of certain ExomiRs such as Exomir-515-5p, ExomiR-221, and ExomiR-96 serve a regulatory role in overcoming insulin resistance. Taken together, the current review focuses on the prospective capabilities of ExomiRs for diagnosis and clinical prognosis of GDM women with respect to pregnancy outcomes.

Impairment of insulin signaling pathway PI3K/Akt/mTOR and insulin resistance induced AGEs on diabetes mellitus and neurodegenerative diseases: a perspective review

Insulin resistance is common in type 2 diabetes mellitus (T2DM), neurodegenerative diseases, cardiovascular diseases, kidney diseases, and polycystic ovary syndrome. Impairment in insulin signaling pathways, such as the PI3K/Akt/mTOR pathway, would lead to insulin resistance. It might induce the synthesis and deposition of advanced glycation end products (AGEs), reactive oxygen species, and reactive nitrogen species, resulting in stress, protein misfolding, protein accumulation, mitochondrial dysfunction, reticulum function, and metabolic syndrome dysregulation, inflammation, and apoptosis. It plays a huge role in various neurodegenerative diseases like Parkinson's disease, Alzheimer's disease, Huntington's disease, and Amyloid lateral sclerosis. In this review, we intend to focus on the possible effect of insulin resistance in the progression of neurodegeneration via the impaired P13K/Akt/mTOR signaling pathway, AGEs, and receptors for AGEs.

The Mystery of Exosomes in Gestational Diabetes Mellitus

Gestational diabetes mellitus (GDM) is one of the common pregnancy complications, which increases the risk of short-term and long-term adverse consequences in both the mother and offspring. However, the pathophysiological mechanism of GDM is still poorly understood. Inflammation, insulin resistance and oxidative stress are considered critical factors in the occurrence and development of GDM. Although the lifestyle intervention and insulin are the primary treatment, adverse pregnancy outcomes still cannot be ignored. Exosomes have a specific function of carrying biological information, which can transmit information to target cells and play an essential role in intercellular communication. Their possible roles in normal pregnancy and GDM have been widely concerned. The possibility of exosomal cargos as biomarkers of GDM is proposed. This paper reviews the literature in recent years and discusses the role of exosomes in GDM and their possible mechanisms to provide some reference for the prediction, prevention, and treatment of GDM and improve the outcome of pregnancy.

Effect of dietary pattern on pregnant women with gestational diabetes mellitus and its clinical significance

Gestational diabetes mellitus (GDM) is a common obstetric disease among pregnant women. This study aimed to explore the effect of dietary pattern management to reduce the incidence of GDM. Here, we, retrospectively, analyzed the influence of dietary patterns on the occurrence of GDM and the correlation between dietary patterns and intestinal microbiome distribution and inflammation in pregnant women. Moreover, patients were assigned to the dietary pattern management group and the nondietary pattern management group, and the effects of dietary patterns on the intestinal microbiome distribution and inflammatory factors were investigated. We found that the intestinal microbiome was changed in GDM patients compared with the healthy controls. The relative abundance of probiotics Lactobacillus and Bifidobacterium significantly decreased in patients with GDM. Moreover, compared with the control group, the expression levels of interleukin-6 and tumor necrosis factor-α were significantly increased. Furthermore, dietary pattern management led to intestinal microbiome changes in patients with GDM. In conclusion, dietary pattern management could alleviate GDM via affecting the intestinal microbiome as well as inflammatory conditions in patients.

An insight into major signaling pathways and protein-protein interaction networks involved in the pathogenesis of gestational diabetes mellitus

Gestational diabetes mellitus (GDM) is associated with the increase of glucose in the blood rather than being absorbed by the cells. A better understanding of the signaling pathways is necessary to understand the pathophysiology of GDM. This study provides details about a series of signaling pathways and protein-protein interactions involved in the pathogenesis of GDM and their evaluations in GDM development. Protein-protein interactions were found between proteins of several signaling pathways that suggest interlink between these signaling pathways. Protein-protein interactions were generated with high confidence interaction scores based on textmining, co-occurrence, coexpression, neighborhood, gene fusion, experiments and databases. The dysregulation of signaling pathways may also contribute to the increased risk of complications associated with GDM in the mother and child. Further, studies on signaling pathways involved in the pathogenesis of GDM would help in the development of an effective intervention to prevent GDM along with the identification of key targets for effective therapies in the future. This article is protected by copyright. All rights reserved.

First-Trimester Triglyceride-Glucose Index and Risk of Pregnancy-Related Complications: A Prospective Birth Cohort Study in Southeast China

PURPOSE

To evaluate the relationships of the triglyceride-glucose (TyG) index with pregnancy-related complications (PRCs) and to clarify the predictability of the TyG index for PRCs.

PATIENTS AND METHODS

Totally of 11,387 women with a singleton pregnancy were prospectively followed until after delivery. Maternal fasting lipids and glucose concentration were measured in the first trimester (11 weeks gestation on average). The TyG index was calculated as ln [triglyceride (mg/dL) × fasting plasma glucose (mg/dL)/2]. We used generalized linear models to calculate the relative risks and 95% confidence intervals. Receiver-operating characteristic curve analysis was employed to assess the ability of the TyG index to predict the risks of PRCs.

RESULTS

Smooth spline reveals that the probability of gestational diabetes mellitus (GDM) is intensified with the increasing TyG index. Multivariate logistic regression adjusted for risk factors demonstrates a 1-unit and a 1-SD increment in the TyG index raises the risk of GDM by 3.63 and 1.57 times, respectively. Identically, the risk of GDM maximizes in the TyG quintile 5 (OR: 3.14; 95% CI: 2.55~3.85) relative to the lowest TyG index group. However, no association between TyG index and the risk of other PRCs was observed after full adjustment. The area under receiver operating characteristic curves is 0.647 (95% CI: 0.632-0.66) for GDM, and the optimal predictive cut-off is 8.55, with a specificity of 0.679 and sensitivity of 0.535.

CONCLUSION

The first-trimester TyG index is significantly associated with the risk of incident GDM, while the relationships between the TyG index and other PRCs need further exploration.

Protective effect of carvacrol on liver injury in type 2 diabetic db/db mice

The present study aimed to investigate the protective effect of carvacrol on liver injury in mice with type 2 diabetes mellitus (T2DM) and to assess its potential molecular mechanism. Mice were divided into three groups (n=15/group): Non-diabetic db/m+ mice group, db/db mice group and db/db mice + carvacrol group. In the db/db mice + carvacrol group, db/db mice were administered 10 mg/kg carvacrol daily by gavage for 6 weeks. Fasting blood glucose and insulin levels were separately examined. Pathological changes were observed using hematoxylin and eosin, Masson's trichrome, periodic acid Schiff and reticular fiber staining. In addition, immunohistochemistry, immunofluorescence and western blotting were used to examine the expression levels of Toll-like receptor 4 (TLR4), NF-κB, NALP3, AKT1, phosphorylated (p)-AKT1, insulin receptor (INSR), p-INSR, mTOR, p-mTOR, insulin receptor substrate 1 (IRS1) and p-IRS1 in the liver tissues. The results revealed that carvacrol improved blood glucose and insulin resistance of T2DM db/db mice. After treatment with carvacrol for 6 weeks, the serum levels of TC, TG and LDL-C were markedly reduced, whereas HDL-C levels were significantly increased in db/db mice. Furthermore, carvacrol administration significantly decreased serum ALT and AST levels in db/db mice. Serum BUN, Cre and UA levels were markedly higher in db/db mice compared with those in the control group; however, carvacrol treatment markedly reduced their serum levels in db/db mice. Furthermore, histological examinations confirmed that carvacrol could protect the liver of db/db mice. Carvacrol could ameliorate liver injury induced by T2DM via mediating insulin, TLR4/NF-κB and AKT1/mTOR signaling pathways. The present findings suggested that carvacrol exerted protective effects on the liver in T2DM db/db mice, which could be related to insulin, TLR4/NF-κB and AKT1/mTOR signaling pathways.

Relationship between Functional miR-143/145 Cluster Variants and Susceptibility to Type 2 Diabetes Mellitus: A Preliminary Case-Control Study and Bioinformatics Analyses

Purpose: To investigate the link between two variants (rs4705342 and rs4705343) in the promoter of the miR-143/145 cluster with Type 2 diabetes mellitus (T2DM) risk. Methods:A total of 1200 subjects were genotyped using the ARMS-PCR method. Results: The rs4705342 variant enhanced the risk of T2DM under codominant CC (OR = 3.24; 95% CI: 1.89-5.60), recessive TT+TC (OR = 3.02; 95% CI: 1.77-5.17), and dominant TC+CC (OR = 1.35; 95% CI: 1.08-1.71) genetic models. Individuals carrying the C allele of rs4705342 conferred a 1.43 fold increased risk of T2DM. As regards rs4705343, decreased risk of T2DM was observed under codominant TC (OR = 0.53; 95% CI: 0.42-0.67), over-dominant TT+CC (OR = 0.51; 95% CI: 0.40-0.64), and dominant TC+CC (OR = 0.59; 95% CI: 0.48-0.75) models. Haplotype analysis of the variants showed a 1.941-fold increased risk of T2DM regarding the C T combination. Significant associations were noticed between different haplotypes and lipid indices of T2DM patients. There were no notable changes in p-values after adjustment for BMI. Computational analysis revealed that miR143 and/or miR145 target important genes involved in glucose and lipid metabolism. Conclusions: Functional miR-143/145 variants might influence the risk of T2DM. Hence, clarifying the precise regulatory mechanisms of gene expression in the development of T2DM will significantly guide researchers to find a novel target for therapeutic intervention.

Associations between insulin resistance and adverse pregnancy outcomes in women with gestational diabetes mellitus: a retrospective study

Background

This study aimed to explore the relationship between insulin resistance (IR) and adverse pregnancy outcomes in women with gestational diabetes mellitus (GDM), and to determine the risk factors for IR in women with GDM.

Methods

This study employed a retrospective survey of 710 women diagnosed with GDM. Serum lipids, fasting plasma glucose (FPG), glycosylated hemoglobin (HbA1c), and serum protein were measured in the first trimester (6–12 weeks), and OGTT and fasting insulin tests were performed in the second trimester (24–28 weeks). These results were then used to evaluate IR by homeostasis model assessment (HOMA). When HOMA-IR ≥ 2.0, IR was diagnosed. The relationship between HOMA-IR and adverse pregnancy outcomes was analyzed by a logistic regression model, and multiple stepwise regression was used to analyze the risk factors of IR.

Results

IR significantly increasd the risk of the hypertensive disorders of pregnancy and large for gestational age (LGA) (OR = 5.31,95%CI:1.87,15.10; OR = 1.65,95%CI:1.10, 2.48, respectively) in women with GDM, but not for cesarean section, premature delivery, premature rupture of membranes, postpartum hemorrhage, macrosomia and SGA. Compared to normal groups, greater body mass index (BMI) before pregnancy category (overweight or obesity group) were associated with higher risk of IR in the second trimester, the OR (95% CI) were 4.09 (2.65, 6.30) and 6.52 (2.99, 14.20). And higher level of FPG (OR = 1.63, 95%CI: 1.11, 2.40), TG (OR = 1.32, 95%CI: 1.08, 1.63) and weight gain before diagnosis of GDM (OR = 1.08, 95%CI: 1.02, 1.15) were also associated with higher risk of IR in the second trimester in women with GDM, while age (OR = 0.94, 95%CI: 0.90, 0.98)was the weak protective factor for IR.

Conclusion

GDM with IR in the second trimester increased adverse pregnancy outcomes, especially the risk of hypertensive disorders of pregnancy and LGA. In addition, FPG, HbA1c, and TG in early pregnancy, pre-pregnant BMI and weight gain before diagnosis of GDM were all independent risk factors for IR.

Role of pregnancy on insulin-induced vasorelaxation: the influence of angiotensin II receptors

Insulin resistance is a feature of pregnancy and is associated with increased levels of angiotensin II (Ang II) and insulin. Therefore, pregnancy may change insulin-induced vasodilation through changes in Ang II receptors. Insulin-induced vasorelaxation was evaluated in phenylephrine-precontracted aortic rings of pregnant and non-pregnant rats, using a conventional isolated organ preparation. Experiments were performed in thoracic or abdominal aorta rings with or without endothelium in the presence and absence of N^G-nitro-L-arginine methyl ester (L-NAME) (10^-5 M), losartan (10^-7 M), or PD123319 (10^-7 M). AT1 and AT2 receptor expressions were detected by immunohistochemistry. Insulin-induced vasodilation was endothelium- and nitric oxide-dependent and decreased in the thoracic aorta but increased in the abdominal segment of pregnant rats. The insulin's vasorelaxant effect was increased by losartan mainly on the thoracic aorta. PD123319 decreased insulin-induced vasorelaxation mainly in the pregnant rat abdominal aorta. AT1 receptor expression was decreased while AT2 receptor expression was increased by pregnancy. In conclusion, pregnancy changes insulin-induced vasorelaxation. Moreover, insulin vasodilation is tonically inhibited by AT1 receptors, while AT2 receptors appear to have an insulin-sensitizing effect. The role of pregnancy and Ang II receptors differ depending on the aorta segment. These results shed light on the role of pregnancy and Ang II receptors on the regulation of insulin-mediated vasodilation.

Small-Molecule Kinase Inhibitors for the Treatment of Nononcologic Diseases

Great successes have been achieved in developing small-molecule kinase inhibitors as anticancer therapeutic agents. However, kinase deregulation plays essential roles not only in cancer but also in almost all major disease areas. Accumulating evidence has revealed that kinases are promising drug targets for different diseases, including cancer, autoimmune diseases, inflammatory diseases, cardiovascular diseases, central nervous system disorders, viral infections, and malaria. Indeed, the first small-molecule kinase inhibitor for treatment of a nononcologic disease was approved in 2011 by the U.S. FDA. To date, 10 such inhibitors have been approved, and more are in clinical trials for applications other than cancer. This Perspective discusses a number of kinases and their small-molecule inhibitors for the treatment of diseases in nononcologic therapeutic fields. The opportunities and challenges in developing such inhibitors are also highlighted.

Plasma from obese children increases monocyte-endothelial adhesion and affects intracellular insulin signaling in cultured endothelial cells: Potential role of mTORC1-S6K1

Childhood obesity is characterized by the loss of vascular insulin sensitivity along with altered oxidant-antioxidant state and chronic inflammation, which play a key role in the onset of endothelial dysfunction. We previously demonstrated a reduced insulin-stimulated Nitric Oxide (NO) bioavailability in Human Umbilical Vein Endothelial cells (HUVECs) cultured with plasma from obese pre-pubertal children (OB) compared to those cultured with plasma of normal-weight children (CTRL). However, mechanisms underlying endothelial dysfunction in childhood obesity remains poorly understood. Hence, the present study aimed to better investigate these mechanisms, also considering a potential involvement of mammalian Target Of Rapamycin Complex1 (mTORC1)-ribosomal protein S6 Kinase beta1 (S6K1) pathway. OB-children (N = 32, age: 9.2 ± 1.7; BMI z-score: 2.72 ± 0.31) had higher fasting insulin levels and increased HOMA-IR than CTRL-children (N = 32, age: 8.8 ± 1.2; BMI z-score: 0.33 ± 0.75). In vitro, HUVECs exposed to OB-plasma exhibited significant increase in Reactive Oxygen Species (ROS) levels, higher vascular and intercellular adhesion molecules exposure, together with increased monocytes-endothelial interaction. This was associated with unbalanced pro- and anti-atherogenic endothelial insulin stimulated signaling pathways, as measured by increased Mitogen Activated Protein Kinase (MAPK) and decreased Insulin Receptor Substrate-1 (IRS-1)/protein kinase B (Akt)/ endothelial NO Synthase (eNOS) phosphorylation levels, together with augmented S6K1 activation. Interestingly, inhibition of mTORC1-S6K1 pathway using rapamycin significantly restored the IRS-1/Akt/eNOS activation, suggesting a feedback regulation of IRS-1/Akt signal through S6K1. Overall, our in vitro data shed light on new mechanisms underlying the onset of endothelial dysfunction in childhood obesity.

Involvement of Essential Signaling Cascades and Analysis of Gene Networks in Diabesity

(1) Aims: Diabesity, defined as diabetes occurring in the context of obesity, is a serious health problem that is associated with an increased risk of premature heart attack, stroke, and death. To date, a key challenge has been to understand the molecular pathways that play significant roles in diabesity. In this study, we aimed to investigate the genetic links between diabetes and obesity in diabetic individuals and highlight the role(s) of shared genes in individuals with diabesity. (2) Methods: The interactions between the genes were analyzed using the Search Tool for the Retrieval of Interacting Genes (STRING) tool after the compilation of obesity genes associated with type 1 diabetes (T1D), type 2 diabetes (T2D), and maturity-onset diabetes of the young (MODY). Cytoscape plugins were utilized for enrichment analysis. (3) Results: We identified 546 obesity genes that are associated with T1D, T2D, and MODY. The network backbone of the identified genes comprised 514 nodes and 4126 edges with an estimated clustering coefficient of 0.242. The Molecular Complex Detection (MCODE) generated three clusters with a score of 33.61, 16.788, and 6.783, each. The highest-scoring nodes of the clusters were AGT, FGB, and LDLR genes. The genes from cluster 1 were enriched in FOXO-mediated transcription of oxidative stress, renin secretion, and regulation of lipolysis in adipocytes. The cluster 2 genes enriched in Src homology 2 domain-containing (SHC)-related events triggered by IGF1R, regulation of lipolysis in adipocytes, and GRB2: SOS produce a link to mitogen-activated protein kinase (MAPK) signaling for integrins. The cluster 3 genes ere enriched in IGF1R signaling cascade and insulin signaling pathway. (4) Conclusion: This study presents a platform to discover potential targets for diabesity treatment and helps in understanding the molecular mechanism.

miR-483 is downregulated in pre-eclampsia via targeting insulin-like growth factor 1 (IGF1) and regulates the PI3K/Akt/mTOR pathway of endothelial progenitor cells

AIM

Pre-eclampsia is a serious pregnancy-specific disease with an incidence of 9.4%. MicroRNAs play a key role in regulating factors in pre-eclampsia, but related research is still limited. This study aims to reveal the role and potential mechanisms of miR-483 in pre-eclampsia.

METHODS

miR-483 was detected in venous blood, umbilical cord blood and placental tissue of pre-eclampsia patients by Real-time Quantitative polymerase chain reaction (qRT-PCR). Insulin-like growth factor (IGF1) and miR-483 were detected by qRT-PCR and western blot in endothelial progenitor cells isolated from fetal umbilical cord blood. miR-483 was overexpressed and inhibited to detect changes of IGF1 and PI3K/Akt/mTOR pathway in endothelial progenitor cells by qRT-PCR and western blot.

RESULTS

miR-483 was downregulated in venous blood, umbilical cord blood and placental tissue of pre-eclampsia patients. In endothelial progenitor cells, overexpression of miR-483 inhibited the expression of IGF1, and inhibition of miR-483 promoted the expression of IGF1. miR-483 regulates the expression of PI3K, Akt, and mTOR in endothelial progenitor cells.

CONCLUSION

miR-483 is downregulated in pre-eclampsia and regulates endothelial progenitor cells by targeting IGF1. miR-483 is a potential alternative for diagnosing and treating pre-eclampsia.

Extracellular Vesicles and Insulin Resistance: A Potential Interaction in Vascular Dysfunction

Insulin resistance plays a key role in cardiovascular complications associated with diabetes mellitus and hypertensive disorders. In states of insulin resistance several circulating factors may contribute to a defective insulin sensitivity in different tissues, including the vasculature. One of these factors influencing the vascular insulin resistance are the extracellular vesicles. The extracellular vesicles include exosomes, microvesicles, and apoptotic bodies which are released to the circulation by different vascular cells. Since the cargo of extracellular vesicles seems to be altered in metabolic complications associated with insulin resistance, these vesicles may be candidates contributing to vascular insulin resistance. Despite the studies linking insulin resistance signalling pathways with the vascular effect of extracellular vesicles, the involvement of these structures in vascular insulin resistance is a phenomenon that remains unclear.

Insulin Therapy in Pregnancy Hypertensive Diseases and its Effect on the Offspring and Mother Later in Life

Pregnancy hypertensive disorders such as Preeclampsia (PE) are strongly correlated with insulin resistance, a condition in which the metabolic handling of D-glucose is deficient. In addition, the impact of preeclampsia is enhanced by other insulin-resistant disorders, including polycystic ovary syndrome and obesity. For this reason, there is a clear association between maternal insulin resistance, polycystic ovary syndrome, obesity and the development of PE. However, whether PE is a consequence or the cause of these disorders is still unclear. Insulin therapy is usually recommended to pregnant women with diabetes mellitus when dietary and lifestyle measures have failed. The advantage of insulin therapy for Gestational Diabetes Mellitus (GDM) patients with hypertension is still controversial; surprisingly, there are no studies in which insulin therapy has been used in patients with hypertension in pregnancy without or with an established GDM. This review is focused on the use of insulin therapy in hypertensive disorders in the pregnancy and its effect on offspring and mother later in life. PubMed and relevant medical databases have been screened for literature covering research in the field especially in the last 5-10 years.

Effects of Maternal Resveratrol on Maternal High-Fat Diet/Obesity with or without Postnatal High-Fat Diet

To examine the effects of maternal resveratrol in rats borne to dams with gestational high-fat diet (HFD)/obesity with or without postnatal high-fat diet. We first tested the effects of maternal resveratrol intake on placenta and male fetus brain in rats borne to dams with gestational HFD/obesity. Then, we assessed the possible priming effect of a subsequent insult, male offspring were weaned onto either a rat chow or a HFD. Spatial learning and memory were assessed by Morris water maze test. Blood pressure and peripheral insulin resistance were examined. Maternal HFD/obesity decreased adiponectin, phosphorylation alpha serine/threonine-protein kinase (pAKT), sirtuin 1 (SIRT1), and brain-derived neurotrophic factor (BDNF) in rat placenta, male fetal brain, and adult male offspring dorsal hippocampus. Maternal resveratrol treatment restored adiponectin, pAKT, and BDNF in fetal brain. It also reduced body weight, peripheral insulin resistance, increased blood pressure, and alleviated cognitive impairment in adult male offspring with combined maternal HFD and postnatal HFD. Maternal resveratrol treatment restored hippocampal pAKT and BDNF in rats with combined maternal HFD and postnatal HFD in adult male offspring dorsal hippocampus. Maternal resveratrol intake protects the fetal brain in the context of maternal HFD/obesity. It effectively reduced the synergistic effects of maternal HFD/obesity and postnatal HFD on metabolic disturbances and cognitive impairment in adult male offspring. Our data suggest that maternal resveratrol intake may serve as an effective therapeutic strategy in the context of maternal HFD/obesity.

AMPK activation suppresses mTOR/S6K1 phosphorylation and induces leucine resistance in rats with sepsis

Although it has been known that protein synthesis is suppressed in sepsis, which cannot be corrected by leucine supplement (also known as leucine resistance), the molecular signaling mechanism remains unclear. This study aimed to investigate the AMP-activated protein kinase/mammalian target of rapamycin (AMPK/mTOR) pathway in sepsis-induced leucine resistance and its upstream signals, and to seek a way to correct leucine resistance in sepsis. Sepsis was produced by cecal ligation and puncture (CLP) model in rat. Both septic rats and sham operation rat received total parenteral nutrition (TPN) with or without leucine for 24 h, and then protein synthesis and AMPK/mTOR and protein kinase B (PKB) were tested. In vitro C2C12 cells were treated with or without leucine, and we tested the AMPK/mTOR pathway and protein synthesis. We blocked AMPK by compound C and stimulated it by 5-aminoimidazole-4-carboxamide ribonucleoside (AICAR) individually. The results showed that AMPK was highly phosphorylated and suppressed mTOR/S6K1 activation in CLP rats. In vitro when AMPK was activated by AICAR, protein synthesis was suppressed and leucine resistance was observed. High phosphorylation of AMPK was accompanied by PKB inactivation in CLP rats. When PKB was blocked, both AMPK activation and leucine resistance were observed. In CLP rats, nutrition support with intensive insulin therapy reversed leucine resistance by activating PKB and suppressing AMPK phosphorylation. These findings suggest that high phosphorylation of AMPK induced by PKB inactivation in sepsis suppresses mTOR, S6K1 phosphorylation, and protein synthesis and leads to leucine resistance. Intensive insulin treatment can reverse leucine resistance by suppressing AMPK activation through activation of PKB.

Neonates from women with pregestational maternal obesity show reduced umbilical vein endothelial response to insulin

OBJECTIVE

Pregestational maternal obesity (PGMO) associates with foetoplacental vascular endothelial dysfunction and higher risk for insulin resistance in the neonate. We characterised the PGMO consequences on the insulin response of the human foetoplacental vasculature.

METHODS

Umbilical veins were from pregnancies where the mother was with PGMO (body mass index 30-42.3 kg/m², n = 33) or normal pregestational weight (PGMN) (body mass index 19.5-24.4 kg/m², n = 21) with total gestational weight gain within the physiological range. Umbilical vein ring segments were mounted in a myograph for isometric force measurements. Primary cultures of human umbilical vein endothelial cells were used in passage 3. Vessel rings and cells were exposed to 1 nmol/L insulin (20 min) in the absence or presence of 100 μmol/L N^G-nitro-l-arginine methyl ester (inhibitor of nitric oxide synthase, NOS).

RESULTS

Vessel rings from PGMO showed reduced nitric oxide synthase-activity dependent dilation to insulin or calcitonin-gene related peptide compared with PGMN. PGMO associated with higher inhibitor phosphorylation of the insulin receptor substrate 1 (IRS-1) and lower activator phosphorylation of protein kinase B/Akt (Akt). Cells from PGMO also showed lower nitric oxide level and reduced activator serine¹¹⁷⁷ but increased inhibitor threonine⁴⁹⁵ phosphorylation of endothelial nitric oxide synthase (eNOS) and saturable transport of l-arginine. HUVECs from PGMO were not responsive to insulin.

CONCLUSION

The lack of response to insulin by the foetoplacental endothelium may result from reduced IRS-1/Akt/eNOS signalling in PGMO. These findings may result in higher risk of insulin resistance in neonates to PGMO pregnancies.

Role of mammalian target of rapamycin signaling pathway in regulation of fatty acid oxidation in a preeclampsia-like mouse model treated with pravastatin

Background:

Fatty acid oxidation (FAO) disorder is involved in the pathogenesis of some cases of preeclampsia (PE). Several studies show that mammalian target of rapamycin (mTOR) signaling pathway is related to FAO. Pravastatin (Pra) can promote FAO in Nω-nitro-L-arginine methyl ester (L-NAME) PE-like mouse model in our previous study. This study aimed to investigate the effect of mTOR signaling pathway in PE-like model treated with Pra.

Methods:

Pregnant mice were randomly injected with L-NAME as PE-like model group or saline as control group respectively, from gestational 7th to 18th day. Giving Pra (L-NAME + Pra, Control + Pra, n = 8) or normal saline (NS; L-NAME + NS, Control + NS, n = 8) from gestational 8th to 18th day, the mice were sacrificed on day 18 and their liver and placental tissues were collected. Then the activation of mTOR and its substrates in the liver and placenta were detected. And the association between mTOR activation and serum free fatty acid (FFA) levels and the expression of long-chain 3-hydroxyacyl-coenzyme A dehydrogenase (LCHAD) were evaluated using Pearson correlation test. Differences between groups were analyzed using independent t-test or one-way analysis of variance (ANOVA).

Results:

Both in the maternal liver and placenta, the activation of mTOR protein and its effect on substrates increased significantly in the L-NAME + NS group and decreased significantly in the L-NAME + Pra group. The p-mTOR/mTOR protein ratio decreased in the L-NAME + Pra group significantly than that in the L-NAME + NS group both in liver and placenta (liver: 0.74 ± 0.08 vs. 0.85 ± 0.06, t = 2.95, P < 0.05; placenta: 0.63 ± 0.06 vs. 0.77 ± 0.06, t = 4.64, P < 0.05). The activation of mTOR protein in the liver and placenta negatively correlated with the expression of LCHAD in the L-NAME + NS group (liver: r = −0.745, P < 0.05; placenta: r = −0.833, P < 0.05) and that in the maternal liver negatively correlated with the expression of LCHAD (r = −0.733, P < 0.05) and positively with the serum FFA levels (r = 0.841, P < 0.05) in the L-NAME + Pra group.

Conclusion:

The inhibition of mTOR signaling pathway might be involved in the regulation of FAO in mouse model treated with Pra.

Downregulation of receptor tyrosine kinase-like orphan receptor 1 in preeclampsia placenta inhibits human trophoblast cell proliferation, migration, and invasion by PI3K/AKT/mTOR pathway accommodation

INTRODUCTION

Invasive deficiency of the trophoblast and poor remodeling of the uterine spiral arteries were probably the primary pathogenesis causes of preeclampsia (PE). The expression of receptor tyrosine kinase-like orphan receptor 1 (ROR1) during embryogenesis had been previously confirmed and was closely related to the function of tumor cells, which was similar to the characteristics of trophoblasts. In this work, we investigated the expression profile of ROR1 in preeclampsia placentas and the functional role of ROR1 in trophoblast cells, as well as the associated molecular mechanisms.

METHODS

The localization expression of ROR1 in the placenta was detected by immunohistochemistry in 20 cases of normal term pregnancy, preterm delivery, late-onset severe PE, and early-onset severe PE, respectively. The expression levels were determined by fluorescence quantitative PCR and Western blot. The influence of ROR1 on trophoblast proliferation, migration, invasion, and potential regulatory pathways was evaluated in HTR-8/SVneo cell lines by transient transfection methods.

RESULTS

The levels of ROR1 in the placental tissues in PE were significantly lower than those in normal term pregnancy and preterm delivery. Moreover, the expression levels of ROR1 in early-onset severe PE were significantly lower than those in its late counterparts. ROR1 overexpression increased cell proliferation, migration, and invasion of HTR-8/SVneo cells, whereas its silencing had the opposite effect. Meanwhile, the phosphorylation levels of critical kinases in the PI3K/AKT/mTOR pathways were increased by ROR1 overexpression, whereas they were decreased by the silencing of ROR1.

CONCLUSION

ROR1 might be involved in the development of PE through regulating trophoblast viability, migration, and invasion by PI3K/AKT/mTOR signaling pathway.

Endothelial dysfunction in pregnancy metabolic disorders

In recent years, the vascular endothelium has gained attention as a key player in the initiation and development of pregnancy disorders. Endothelium acts as an endocrine organ that preserves the homeostatic balance by responding to changes in metabolic status. However, in metabolic disorders, endothelial cells adopt a dysfunctional function, losing their normal responsiveness. During pregnancy, several metabolic changes occur, in which endothelial function decisively participates. Similarly, when pregnancy metabolic disorders occur, endothelial dysfunction plays a key role in pathogenesis. This review outlines the main findings regarding endothelial dysfunction in three main metabolic pathological conditions observed during pregnancy: gestational diabetes, hypertensive disorders, and obesity and hyperlipidemia. Organ, histological and cellular characteristics were thoroughly described. Also, we focused in discussing the underlying molecular mechanisms involved in the cellular signaling pathways that mediate responses in these pathological conditions.

Role of insulin, adenosine, and adipokine receptors in the foetoplacental vascular dysfunction in gestational diabetes mellitus

Gestational diabetes mellitus (GDM) is a disease of pregnancy associated with maternal and foetal hyperglycaemia and altered foetoplacental vascular function. Human foetoplacental microvascular and macrovascular endothelium from GDM pregnancy show increased maximal l-arginine transport capacity via the human cationic amino acid transporter 1 (hCAT-1) isoform and nitric oxide (NO) synthesis by the endothelial NO synthase (eNOS). These alterations are paralleled by lower maximal transport activity of the endogenous nucleoside adenosine via the human equilibrative nucleoside transporter 1 (hENT1) and activation of adenosine receptors. A causal relationship has been described for adenosine-activation of A_2A adenosine receptors, hCAT-1, and eNOS activity (i.e. the Adenosine/l-Arginine/Nitric Oxide, ALANO, signalling pathway). Insulin restores these alterations in GDM via activation of insulin receptor A (IR-A) form in the macrovascular but IR-A and IR-B forms in the microcirculation of the human placenta. Adipokines are secreted from adipocytes influencing the foetoplacental metabolic and vascular function. Various adipokines are dysregulated in GDM, with adiponectin and leptin playing major roles. Abnormal plasma concentration of these adipokines and the activation or their receptors are involved in the pathophysiology of GDM. However, involvement of adipokines, adenosine, and insulin receptors and membrane transporters in the aetiology of this disease of pregnancy is unknown. This review focuses on the pathophysiology of insulin and adenosine receptors and l-arginine and adenosine membranes transporters giving an overview of the key adipokines leptin and adiponectin in the foetoplacental vasculature in GDM. This article is part of a Special Issue entitled: Membrane Transporters and Receptors in Pregnancy Metabolic Complications edited by Luis Sobrevia.

Endoplasmic reticulum stress and development of insulin resistance in adipose, skeletal, liver, and foetoplacental tissue in diabesity

Diabesity is an abnormal metabolic condition shown by patients with obesity that develop type 2 diabetes mellitus. Patients with diabesity present with insulin resistance, reduced vascular response to insulin, and vascular endothelial dysfunction. Along with the several well-described mechanisms of insulin resistance, a state of endoplasmic reticulum (ER) stress, where the primary human targets are the adipose tissue, liver, skeletal muscle, and the foetoplacental vasculature, is apparent. ER stress characterises by the activation of the unfolded protein response via three canonical ER stress sensors, i.e., the protein kinase RNA-like endoplasmic reticulum kinase (PERK), inositol-requiring enzyme 1α (IRE1α), and activating transcription factor 6. Slightly different cell signalling mechanisms preferentially enable in diabesity in the ER stress-associated insulin resistance for adipose tissue (IRE1α/X-box binding protein 1 mRNA splicing/c-jun N-terminal kinase 1 activation), skeletal muscle (tribbles-like protein 3 (TRB3)/proinflammatory cytokines activation), and liver (PERK/activating transcription factor 4/TRB3 activation). There is no information in human subjects with diabesity in the foetoplacental vasculature. However, the available literature shows that pregnant women with pre-pregnancy obesity or overweight that develop gestational diabetes mellitus (GDM) and their newborn show insulin resistance. ER stress is recently reported to be triggered in endothelial cells from the human umbilical vein from mothers with pre-pregnancy obesity. However, whether a different metabolic alteration to obesity in pregnancy or GDM is present in women with pre-pregnancy obesity that develop GDM, is unknown. In this review, we summarised the findings on diabesity-associated mechanisms of insulin resistance with emphasis in the primary targets adipose, skeletal muscle, liver, and foetoplacental tissues. We also give evidence on the possibility of a new GDM-associated metabolic condition triggered in pregnancy by maternal obesity, i.e. gestational diabesity, leading to ER stress-associated insulin resistance in the human foetoplacental vasculature.

The Proposal of Molecular Mechanisms of Weak Organic Acids Intake-Induced Improvement of Insulin Resistance in Diabetes Mellitus via Elevation of Interstitial Fluid pH

Blood contains powerful pH-buffering molecules such as hemoglobin (Hb) and albumin, while interstitial fluids have little pH-buffering molecules. Thus, even under metabolic disorder conditions except severe cases, arterial blood pH is kept constant within the normal range (7.35~7.45), but the interstitial fluid pH under metabolic disorder conditions becomes lower than the normal level. Insulin resistance is one of the most important key factors in pathogenesis of diabetes mellitus, nevertheless the molecular mechanism of insulin resistance occurrence is still unclear. Our studies indicate that lowered interstitial fluid pH occurs in diabetes mellitus, causing insulin resistance via reduction of the binding affinity of insulin to its receptor. Therefore, the key point for improvement of insulin resistance occurring in diabetes mellitus is development of methods or techniques elevating the lowered interstitial fluid pH. Intake of weak organic acids is found to improve the insulin resistance by elevating the lowered interstitial fluid pH in diabetes mellitus. One of the molecular mechanisms of the pH elevation is that: (1) the carboxyl group (R-COO⁻) but not H⁺ composing weak organic acids in foods is absorbed into the body, and (2) the absorbed the carboxyl group (R-COO⁻) behaves as a pH buffer material, elevating the interstitial fluid pH. On the other hand, high salt intake has been suggested to cause diabetes mellitus; however, the molecular mechanism is unclear. A possible mechanism of high salt intake-caused diabetes mellitus is proposed from a viewpoint of regulation of the interstitial fluid pH: high salt intake lowers the interstitial fluid pH via high production of H⁺ associated with ATP synthesis required for the Na⁺,K⁺-ATPase to extrude the high leveled intracellular Na⁺ caused by high salt intake. This review article introduces the molecular mechanism causing the lowered interstitial fluid pH and insulin resistance in diabetes mellitus, the improvement of insulin resistance via intake of weak organic acid-containing foods, and a proposal mechanism of high salt intake-caused diabetes mellitus.

Extracellular histones activate autophagy and apoptosis via mTOR signaling in human endothelial cells

Circulating histones have been proposed as targets for therapy in sepsis and hyperinflammatory symptoms. However, the proposed strategies have failed in clinical trials. Although different mechanisms for histone-related cytotoxicity are being explored, those mediated by circulating histones are not fully understood. Extracellular histones induce endothelial cell death, thereby contributing to the pathogenesis of complex diseases such as sepsis and septic shock. Therefore, the comprehension of cellular responses triggered by histones is capital to design effective therapeutic strategies. Here we report how extracellular histones induce autophagy and apoptosis in a dose-dependent manner in cultured human endothelial cells. In addition, we describe how histones regulate these pathways via Sestrin2/AMPK/ULK1-mTOR and AKT/mTOR. Furthermore, we evaluate the effect of Toll-like receptors in mediating autophagy and apoptosis demonstrating how TLR inhibitors do not prevent apoptosis and/or autophagy induced by histones. Our results confirm that histones and autophagic pathways can be considered as novel targets to design therapeutic strategies in endothelial damage.

Pre-pregnancy maternal obesity associates with endoplasmic reticulum stress in human umbilical vein endothelium

Obesity associates with the endoplasmic reticulum (ER) stress-induced endothelial dysfunction. Pregnant women with pre-pregnancy maternal obesity (PGMO) may transfer this potential risk to their offspring; however, whether ER stress occurs and associates with foetoplacental endothelial dysfunction in PGMO is unknown. We studied the l-arginine transport and nitric oxide (NO) synthesis in human umbilical vein endothelial cells (HUVECs) from women with PGMO or with a normal pre-pregnancy weight. We analysed the expression and activation of the ER stress sensors protein kinase RNA-like endoplasmic reticulum kinase (PERK), inositol-requiring enzyme 1α (IRE1α), and activating transcription factor 6 (ATF6). PGMO associated with lower endothelial NO synthase activity due to increased Thr⁴⁹⁵-inhibitor and decreased Ser¹¹⁷⁷-stimulator phosphorylation. However, higher expression and activity of the human cationic amino acid transporter 1 was found. PGMO caused activation of PERK and its downstream targets eukaryotic initiation factor 2 (eIF2α), C/EBP homologous protein 10 (CHOP), and tribbles-like protein 3 (TRB3). Increased IRE1α protein abundance (but not its phosphorylation or X-box binding protein 1-mRNA splicing) and increased c-Jun N-terminal kinase 1 phosphorylation was seen in PGMO. A preferential nuclear location of the activating transcription factor 6 (ATF6) was found in HUVECs from PGMO. All the changes seen in PGMO were blocked by TUDCA but unaltered by tunicamycin. Thus, PGMO may determine a state of ER stress via upregulation of the PERK-eIF2α-CHOP-TRB3 axis signalling in HUVECs. This phenomenon results in foetoplacental vascular endothelial dysfunction at birth.

Insulin therapy and its consequences for the mother, foetus, and newborn in gestational diabetes mellitus

Gestational diabetes mellitus (GDM) is a disease characterised by glucose intolerance and first diagnosed in pregnancy. This condition relates to an anomalous placental environment and aberrant placental vascular function. GDM-associated hyperglycaemia changes the placenta structure leading to abnormal development and functionality of this vital organ. Aiming to avoid the GDM-hyperglycaemia and its deleterious consequences in the mother, the foetus and newborn, women with GDM are firstly treated with a controlled diet therapy; however, some of the women fail to reach the recommended glycaemia values and therefore they are passed to the second line of treatment, i.e., insulin therapy. The several protocols available in the literature regarding insulin therapy are variable and not a clear consensus is yet reached. Insulin therapy restores maternal glycaemia, but this beneficial effect is not reflected in the foetus and newborn metabolism, suggesting that other factors than d-glucose may be involved in the pathophysiology of GDM. Worryingly, insulin therapy may cause alterations in the placenta and umbilical vessels as well as the foetus and newborn additional to those seen in pregnant women with GDM treated with diet. In this review, we summarised the variable information regarding indications and protocols for administration of the insulin therapy and the possible outcomes on the function and structure of the foetoplacental unit and the neonate parameters from women with GDM.