Increase in placental apolipoprotein D as an adaptation to human gestational diabetes

Apolipoprotein D in Oxidative Stress and Inflammation

Apolipoprotein D (ApoD) is lipocalin able to bind hydrophobic ligands. The APOD gene is upregulated in a number of pathologies, including Alzheimer's disease, Parkinson's disease, cancer, and hypothyroidism. Upregulation of ApoD is linked to decreased oxidative stress and inflammation in several models, including humans, mice, Drosophila melanogaster and plants. Studies suggest that the mechanism through which ApoD modulates oxidative stress and regulate inflammation is via its capacity to bind arachidonic acid (ARA). This polyunsaturated omega-6 fatty acid can be metabolised to generate large variety of pro-inflammatory mediators. ApoD serves as a sequester, blocking and/or altering arachidonic metabolism. In recent studies of diet-induced obesity, ApoD has been shown to modulate lipid mediators derived from ARA, but also from eicosapentaenoic acid and docosahexaenoic acid in an anti-inflammatory way. High levels of ApoD have also been linked to better metabolic health and inflammatory state in the round ligament of morbidly obese women. Since ApoD expression is upregulated in numerous diseases, it might serve as a therapeutic agent against pathologies aggravated by OS and inflammation such as many obesity comorbidities. This review will present the most recent findings underlying the central role of ApoD in the modulation of both OS and inflammation.

Natural killer cells promote intra-cellular-infected trophoblasts survival via APOD-LRP1 axis

Natural killer (NK) cells are known for their potent ability to kill stressed cells, whereas host cells infected with intra-cellular bacteria may also be benefit from the selective killing function of NK cells and survive. The mechanism of how NK cells protect host cells infected with intra-cellular bacteria is still unclear. Here, we discovered that decidual NK (dNK) cells cannot only eliminate intra-cellular bacteria which infected trophoblasts, but can also synthesize more lipids and transport lipids to trophoblasts to avoid their apoptosis. Mechanically, NK cells synthesize more lipids accompanied by increasing expression of apolipoprotein APOD. Lipids in NK cells can be delivered to trophoblast cells through APOD, maintaining adequate lipid droplet content and lipid metabolism homeostasis in trophoblasts. Blocking the APOD receptor LRP1 abolished lipid transport from NK cells to trophoblasts, and the reduction of lipid droplets caused by bacterial infection in trophoblast cells could not be restored, culminating in cell apoptosis. Our study provides new evidence for the immune surveillance and protective effect of NK cells on embryos during early pregnancy.

The Lipocalin Apolipoprotein D Functional Portrait: A Systematic Review

Apolipoprotein D is a chordate gene early originated in the Lipocalin protein family. Among other features, regulation of its expression in a wide variety of disease conditions in humans, as apparently unrelated as neurodegeneration or breast cancer, have called for attention on this gene. Also, its presence in different tissues, from blood to brain, and different subcellular locations, from HDL lipoparticles to the interior of lysosomes or the surface of extracellular vesicles, poses an interesting challenge in deciphering its physiological function: Is ApoD a moonlighting protein, serving different roles in different cellular compartments, tissues, or organisms? Or does it have a unique biochemical mechanism of action that accounts for such apparently diverse roles in different physiological situations? To answer these questions, we have performed a systematic review of all primary publications where ApoD properties have been investigated in chordates. We conclude that ApoD ligand binding in the Lipocalin pocket, combined with an antioxidant activity performed at the rim of the pocket are properties sufficient to explain ApoD association with different lipid-based structures, where its physiological function is better described as lipid-management than by long-range lipid-transport. Controlling the redox state of these lipid structures in particular subcellular locations or extracellular structures, ApoD is able to modulate an enormous array of apparently diverse processes in the organism, both in health and disease. The new picture emerging from these data should help to put the physiological role of ApoD in new contexts and to inspire well-focused future research.

Adipose-Derived Lipid-Binding Proteins: The Good, the Bad and the Metabolic Diseases

Adipose tissue releases a large range of bioactive factors called adipokines, many of which are involved in inflammation, glucose homeostasis and lipid metabolism. Under pathological conditions such as obesity, most of the adipokines are upregulated and considered as deleterious, due to their pro-inflammatory, pro-atherosclerotic or pro-diabetic properties, while only a few are downregulated and would be designated as beneficial adipokines, thanks to their counteracting properties against the onset of comorbidities. This review focuses on six adipose-derived lipid-binding proteins that have emerged as key factors in the development of obesity and diabetes: Retinol binding protein 4 (RBP4), Fatty acid binding protein 4 (FABP4), Apolipoprotein D (APOD), Lipocalin-2 (LCN2), Lipocalin-14 (LCN14) and Apolipoprotein M (APOM). These proteins share structural homology and capacity to bind small hydrophobic molecules but display opposite effects on glucose and lipid metabolism. RBP4 and FABP4 are positively associated with metabolic syndrome, while APOD and LCN2 are ubiquitously expressed proteins with deleterious or beneficial effects, depending on their anatomical site of expression. LCN14 and APOM have been recently identified as adipokines associated with healthy metabolism. Recent findings on these lipid-binding proteins exhibiting detrimental or protective roles in human and murine metabolism and their involvement in metabolic diseases are also discussed.

Immunoendocrine Dysregulation during Gestational Diabetes Mellitus: The Central Role of the Placenta

Gestational Diabetes Mellitus (GDM) is a transitory metabolic condition caused by dysregulation triggered by intolerance to carbohydrates, dysfunction of beta-pancreatic and endothelial cells, and insulin resistance during pregnancy. However, this disease includes not only changes related to metabolic distress but also placental immunoendocrine adaptations, resulting in harmful effects to the mother and fetus. In this review, we focus on the placenta as an immuno-endocrine organ that can recognize and respond to the hyperglycemic environment. It synthesizes diverse chemicals that play a role in inflammation, innate defense, endocrine response, oxidative stress, and angiogenesis, all associated with different perinatal outcomes.

Molecular pathophysiology of diabetes mellitus during pregnancy with antenatal complications

Gestational diabetes mellitus is a daunting problem accompanied by severe fetal development complications and type 2 diabetes mellitus in postpartum. Diagnosis of diabetic conditions occurs only in the second trimester, while associated antenatal complications are typically revealed even later. We acquired an assay of peripheral and cord blood samples of patients with different types of diabetes mellitus who delivered either healthy newborns or associated with fetopathy complications. Obtained data were handled with qualitative and quantitative analysis. Pathways of molecular events involved in diabetes mellitus and fetopathy were reconstructed based on the discovered markers and their quantitative alteration. Plenty of pathways were integrated to differentiate the type of diabetes and to recognize the impact of the diabetic condition on fetal development. The impaired triglycerides transport, glucose uptake, and consequent insulin resistance are mostly affected by faulted lipid metabolism (APOM, APOD, APOH, APOC1) and encouraged by oxidative stress (CP, TF, ORM2) and inflammation (CFH, CFB, CLU) as a secondary response accompanied by changes in matrix architecture (AFM, FBLN1, AMBP). Alterations in proteomes of peripheral and cord blood were expectedly unequal. Both up- and downregulated markers were accommodated in the cast of molecular events interconnected with the lipid metabolism, RXR/PPAR-signaling pathway, and extracellular architecture modulation. The obtained results congregate numerous biological processes to molecular events that underline diabetes during gestation and uncover some critical aspects affecting fetal growth and development.

Biomarkers of oxidative stress in pregnancy complications

Pregnancy complications including pre-eclampsia, gestational-diabetes mellitus, preterm birth and intrauterine growth restriction can cause acute and chronic health problems for the mother and lead to fetal loss or dysregulation of infant physiology. The human placenta is susceptible to oxidative stress and oxidative damage in early gestation contributes to the onset of these conditions later in pregnancy. Current methods of predicting pregnancy complications are limited and although a large number of factors are associated with disease progression, few biomarkers have been used to aid in disease diagnosis early in gestation. This review discusses the detection of oxidative stress markers in biological fluids and highlights the need for further studies to validate their use in the prediction or diagnosis of pregnancy disorders.

Prenatal nonylphenol exposure, oxidative and nitrative stress, and birth outcomes: A cohort study in Taiwan

Data concerning the effects of prenatal exposures to nonylphenol (NP) and oxidative stress on neonatal birth outcomes from human studies are limited. A total of 146 pregnant women were studied (1) to investigate the association between prenatal NP exposure and maternal oxidative/nitrative stress biomarkers of DNA damage (8-hydroxy-2'-deoxyguanosine (8-OHdG), 8-nitroguanine (8-NO2Gua)) and lipid peroxidation (8-iso-prostaglandin F2α (8-isoPF2α), 4-hydroxy-2-nonenal-mercapturic acid (HNE-MA)) and (2) to explore the associations among oxidative stress biomarkers, NP exposure, and neonatal birth outcomes, including gestational age, birth weight, length, Ponderal index, and head and chest circumferences. NP significantly increased the 8-OHdG and 8-NO2Gua levels. All infants born to mothers with urinary 8-OHdG levels above the median exhibited a significantly shorter gestational duration (Badjusted = -4.72 days; 95% CI: -8.08 to -1.36 days). No clear association was found between NP levels and birth outcomes. Prenatal 8-OHdG levels might be a novel biomarker for monitoring fetal health related to NP exposure.

The relationship between the oxidative stress and the cardiac hypertrophy in infants of diabetic mothers

Recently, oxidative stress was suggested to play a role in maternal and fetal complications of diabetic pregnancies. The aim of this study is to evaluate the global oxidant and antioxidant status in infants of diabetic mothers (IDM) via measurement of total antioxidant capacity (TAC) and total oxidant status (TOS) and to determine their association with the clinical and cardiac manifestations of gestational diabetes on infants. Forty five infants constituted the IDM group, 51 infants born to non diabetic mothers served as the control group. Umbilical cord blood was drawn from IDM and controls for TAC and TOS measurement. Echocardiographic measurements were performed in the first three days of life. Infants of diabetic mother had significantly higher TAC (p=0.024), TOS (p=0.03) and oxidative stress index (OSI, p=0.04) levels compared to controls. Hemoglobin values were correlated to TOS (r=0.310, p=0.03) and OSI (r=0.310, p=0.03). Maternal HbA1c values were also correlated to TOS (r=0.576, p=0.001) and OSI (r=0.606, p<0.001). Systolic and diastolic interventicular septum measurements, and left ventricular mass were also correlated with TOS (r=0.330, p=0.02; r=0.453, p=0.002; r=0.404, p=0.006, respectively) and OSI (r=0.330, p=0.02; r=0.300, p=0.04, r=0.300; p=0.04, respectively). Oxidant-antioxidant balance is disturbed in favor of oxidants in IDM despite compensatory increase in TAC. The degree of oxidative stress is related to the severity of myocardial and hematological involvement in IDM in the first days of life and maternal glycemic control.

Variations in apolipoprotein D and sigma non-opioid intracellular receptor 1 genes with relation to risk, severity and outcome of ischemic stroke

BACKGROUND

In experimental studies, the apolipoprotein D (APOD) and the sigma receptor type 1 (SIGMAR1) have been related to processes of brain damage, repair and plasticity.

METHODS

We examined blood samples from 3081 ischemic stroke (IS) patients and 1595 control subjects regarding 10 single nucleotide polymorphisms (SNPs) in the APOD (chromosomal location 3q29) and SIGMAR1 (chromosomal location 9p13) genes to find possible associations with IS risk, IS severity (NIHSS-score) and recovery after IS (modified Rankin Scale, mRS, at 90 days). Simple/multiple logistic regression and Spearman's rho were utilized for the analyses.

RESULTS

Among the SNPs analyzed, rs7659 within the APOD gene showed a possible association with stroke risk (OR = 1.12; 95% CI: 1.01-1.25; P = 0.029) and stroke severity (NIHSS ≥ 16) (OR = 0.70; 95% CI: 0.54-0.92; P = 0.009) when controlling for age, sex and vascular risk factors for stroke. No SNP showed an association with stroke recovery (mRS).

CONCLUSIONS

We conclude that the SNP rs7659 within the APOD gene might be related to risk and severity of ischemic stroke in patients.

The role of oxidative stress in the pathophysiology of gestational diabetes mellitus

Normal human pregnancy is considered a state of enhanced oxidative stress. In pregnancy, it plays important roles in embryo development, implantation, placental development and function, fetal development, and labor. However, pathologic pregnancies, including gestational diabetes mellitus (GDM), are associated with a heightened level of oxidative stress, owing to both overproduction of free radicals and/or a defect in the antioxidant defenses. This has important implications on the mother, placental function, and fetal well-being. Animal models of diabetes have confirmed the important role of oxidative stress in the etiology of congenital malformations; the relative immaturity of the antioxidant system facilitates the exposure of embryos and fetuses to the damaging effects of oxidative stress. Of note, there are only a few clinical studies evaluating the potential beneficial effects of antioxidants in GDM. Thus, whether or not increased antioxidant intake can reduce the complications of GDM in both mother and fetus needs to be explored. This review provides an overview and updated data on our current understanding of the complications associated with oxidative changes in GDM.