Iron Metabolism in Obesity and Metabolic Syndrome González-Domínguez, Álvaro; Visiedo-García, Francisco M; Domínguez-Riscart, Jesús ...
International journal of molecular sciences,
2020-Aug-01, 2020-08-01, 20200801, Letnik:
21, Številka:
15
Journal Article
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Obesity is an excessive adipose tissue accumulation that may have detrimental effects on health. Particularly, childhood obesity has become one of the main public health problems in the 21st century, ...since its prevalence has widely increased in recent years. Childhood obesity is intimately related to the development of several comorbidities such as nonalcoholic fatty liver disease, dyslipidemia, type 2 diabetes mellitus, non-congenital cardiovascular disease, chronic inflammation and anemia, among others. Within this tangled interplay between these comorbidities and associated pathological conditions, obesity has been closely linked to important perturbations in iron metabolism. Iron is the second most abundant metal on Earth, but its bioavailability is hampered by its ability to form highly insoluble oxides, with iron deficiency being the most common nutritional disorder. Although every living organism requires iron, it may also cause toxic oxygen damage by generating oxygen free radicals through the Fenton reaction. Thus, iron homeostasis and metabolism must be tightly regulated in humans at every level (i.e., absorption, storage, transport, recycling). Dysregulation of any step involved in iron metabolism may lead to iron deficiencies and, eventually, to the anemic state related to obesity. In this review article, we summarize the existent evidence on the role of the most recently described components of iron metabolism and their alterations in obesity.
Oxidative stress and inflammation have been postulated as underlying mechanisms for the development of obesity-related insulin resistance. This association however, remains elusive especially in ...childhood. We sought to investigate this relation by measuring oxidative stress and antioxidant response biomarkers, before and during an oral glucose tolerance test (OGTT), in different biological samples from obese children.
24 children were recruited for the study, (18 obese and 6 controls). After OGTT, the obese group was subdivided in two, according to whether or not carbohydrate metabolic impairment (Ob.IR+, Ob.IR-; respectively) was found. Different biomarkers were analyzed after fasting (T = 0) and during an OGTT (T = 60 and 120 min). Lipoperoxides were measured in plasma, erythrocytes, and urine; while advanced glycation end products were determined in plasma, and redox status (GSH/GSSG ratio) in erythrocytes.
We found marked differences in the characterization of the oxidative status in urine and erythrocytes, and in the dynamics of the antioxidant response during OGTT. Specifically, Ob.IR+ children show increased oxidative stress, deficient antioxidant response and a significant imbalance in redox status, in comparison to controls and Ob.IR- children.
Obese children with insulin resistance show increased levels of oxidative stress biomarkers, and a stunted antioxidant response to an OGTT leading to increased oxidative stress after a single glucose load, as detected in erythrocytes, but not in plasma. We propose erythrocytes as sensors of early and acute changes in oxidative stress associated with insulin resistance in childhood obesity. This is a pilot study, performed with a limited sample size, so data should be interpreted with caution until reproduced.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
An adverse proinflammatory milieu contributes to abnormal cellular energy metabolism response. Gestational diabetes mellitus (GDM) is closely related to an altered maternal inflammatory status. ...However, its role on lipid metabolism regulation in human placenta has not yet been assessed. The aim of this study was to examine the impact of maternal circulating inflammatory mediators (TNF-α, IL-6, and Leptin) on placental fatty acid metabolism in GDM pregnancies.
Fasting maternal blood and placental tissues were collected at term deliveries from 37 pregnant women (17 control and 20 GDM). Molecular approach techniques as radiolabeled lipid tracers, ELISAs, immunohistochemistry and multianalyte immunoassay quantitative analysis, were used to quantify serum inflammatory factors' levels, to measure lipid metabolic parameters in placental villous samples (mitochondrial fatty acid oxidation FAO rate and lipid content Triglycerides), and to analyze their possible relationships. The effect of potential candidate cytokines on fatty acid metabolism in
placental explants culture following C-section a term was also examined.
Maternal serum IL-6, TNF-α and leptin levels were significantly increased in GDM patients compared with control pregnant women (9,9±4,5 vs. 3,00±1,7; 4,5±2,8 vs. 2,1±1,3; and 10026,7±5628,8 vs. 5360,2±2499,9 pg/ml, respectively). Placental FAO capacity was significantly diminished (~30%; p<0.01), whereas triglyceride levels were three-fold higher (p<0.01) in full-term GDM placentas. Uniquely the maternal IL-6 levels showed an inverse and positive correlation with the ability to oxidize fatty acids and triglyceride amount in placenta, respectively (r= -0,602, p=0.005; r= 0,707, p=0.001). Additionally, an inverse correlation between placental FAO and triglycerides was also found (r=-0.683; p=0.001). Interestingly, we
demonstrated by using placental explant cultures that a prolonged exposure with IL-6 (10 ng/mL) resulted in a decline in the fatty acid oxidation rate (~25%; p=0.001), along to acute increase (2-fold times) in triglycerides accumulation (p=0.001), and in lipid neutral and lipid droplets deposits.
Enhanced maternal proinflammatory cytokines levels (essentially IL-6) is closely associated with an altered placental fatty acid metabolism in pregnancies with GDM, which may interfere with adequate delivery of maternal fat across the placenta to the fetus.
Naringenin is one of the main phenolic compounds found in grapefruit (Citrus × paradisi Macfad.). This compound is known for its therapeutical properties as an antioxidant, antidiabetic, ...antihyperlipidemic and antineoplastic agent. In order to enable the development of drugs based on this compound, an appropriate extraction method needs to be developed. For this study, enzymatic extraction was chosen, as it is a cheap and green extraction method. Optimal extraction conditions (pH, temperature, agitation, solvent composition, sample-to-solvent ratio and enzyme-to-sample ratio) were determined through a Plackett–Burman and a Box–Behnken design, resulting in pH 6.0, 40 °C, 50 rpm, 20% EtOH, 0.2 g sample per 15 mL solvent and 1000 U/g. Once extraction conditions were determined, a single-factor experiment was performed under optimal conditions to determine extraction time, which resulted in 10 min per extraction. Finally, repeatability and intermediate precision were evaluated through naringenin quantification. Good values were obtained for both parameters (1.80% and 2.05%, respectively). Furthermore, extracts presented significant amount of naringenin (0.18 ± 0.02 mg/g).
Lam. is known to have significant antioxidant properties. Because of this, the development of an optimal extraction method is crucial to obtain pharmacological products based on the bioactive ...compounds produced by this tree. Through a Plackett-Burman and a Box-Behnken design, enzymatic extraction conditions (temperature, agitation, solvent pH and composition, sample-to-solvent ratio, enzyme-to-sample ratio and extraction time) have been optimized using normalized areas (UA/g) as response variable and relative mass (mg/g) as quantification variable. Extractions were performed in an incubator, where all the extraction conditions could be digitally controlled. Thus, 58.9 °C, 50 rpm, 4.0 pH, 32.5% EtOH, 0.2 g sample in 15 mL solvent and 106 U/g were established as the optimal extraction conditions for the extraction with a mix of pectinases coming from
. Under these optimal conditions, two-minute extractions were performed and evaluated through a single factor design. The enzymatic extraction method demonstrated its suitability to produce extracts with good antioxidant power (antioxidant activity 4.664 ± 0.059 mg trolox equivalent/g sample and total phenolic compounds 6.245 ± 0.101 mg gallic acid equivalent/g sample). The method was also confirmed to have good repeatability (1.39%) and intermediate precision (2.37%) levels.
The biological activity of glucagon has recently been proposed to both stimulate hepatic glucose production and also include a paradoxical insulinotropic effect, which could suggest a new role of ...glucagon in the pathophysiology type 2 diabetes mellitus (T2DM). An insulinotropic role of glucagon has been observed after bariatric/metabolic surgery that is mediated through the GLP-1 receptor on pancreatic beta cells. This effect appears to be modulated by other members of the proglucagon family, playing a key role in the beneficial effects and complications of bariatric/metabolic surgery. Glucagon serves a dual role after sleeve gastrectomy (SG) and Roux-en-Y gastric bypass (RYGB). In addition to maintaining blood glucose levels, glucagon exhibits an insulinotropic effect, suggesting that glucagon has a more complex function than simply an “anti-insulin hormone”.
Obese women are more likely to experience pregnancy complications. The distribution of fat, and more particularly the rise in visceral fat, is well established to be more closely linked to the onset ...of cardiovascular disease and metabolic syndrome than obesity itself. We aim to examine the relationship between maternal visceral fat assessment in the first trimester and the appearance of adverse pregnancy outcomes. A prospective cohort study including 416 pregnant women was conducted. During the first trimester scan (11-13 + 6 weeks), all individuals had their visceral fat and subcutaneous thicknesses measured by ultrasonography. Blood samples were obtained, and maternal demographics and clinical information were documented. After delivery, the obstetric outcomes were evaluated. We contrasted two groups: one with healthy pregnancies and the other with adverse pregnancy outcomes (APO), defined as the development of at least one of the following complications: gestational diabetes mellitus, hypertensive disorders of pregnancy, abnormal fetal growth, preterm delivery or preterm premature rupture of membranes. Median maternal age was 33 and 34 years old for the uncomplicated and adverse pregnancy outcomes groups, respectively. We found that women with adverse pregnancy outcomes had higher VFT (median 30 vs. 26.5 mm,
= 0.001) and SFT (median 18.9 vs. 17.1 mm,
= 0.03). However, the visceral/subcutaneous fat ratio was not statistically different between groups. Finally, we performed a subanalysis for metabolic and placental vascular dysfunction complications. After performing a multivariate logistic regression analysis adjusted for maternal age, smoking, and mean arterial pressure, both the VFT (aOR 1.03,
< 0.001) and the ratio of visceral/subcutaneous fat (aOR 1.37,
= 0.04) were significantly associated with the development of adverse pregnancy outcomes; however, the associations of VFT and the VFT-to-SFT ratio were higher for the occurrence of gestational diabetes (aOR 1.07,
< 0.001; aOR 2.09,
= 0.001; respectively) and showed no relationships with placental complications. When conducting a first-trimester ultrasound assessment, sonographers may measure VFT without additional time or cost involved. Identification of pregnant women with increased VFT (>37 mm) may benefit from a close follow-up, especially for the development of gestational diabetes, independent of BMI.
Childhood obesity, and specifically its metabolic complications, are related to deficient antioxidant capacity and oxidative stress. Erythrocytes are constantly exposed to multiple sources of ...oxidative stress; hence, they are equipped with powerful antioxidant mechanisms requiring permanent reducing power generation and turnover. Glucose-6-phosphate dehydrogenase (G6PDH) and 6-phosphogluconate dehydrogenase (6PGDH) are two key enzymes on the pentose phosphate pathway. Both enzymes supply reducing power by generating NADPH, which is essential for maintaining the redox balance within the cell and the activity of other antioxidant enzymes. We hypothesized that obese children with insulin resistance would exhibit blunted G6PDH and 6PGDH activities, contributing to their erythrocytes' redox status imbalances. We studied 15 control and 24 obese prepubertal children, 12 of whom were insulin-resistant according to an oral glucose tolerance test (OGTT). We analyzed erythroid malondialdehyde (MDA) and carbonyl group levels as oxidative stress markers. NADP+/NADPH and GSH/GSSG were measured to determine redox status, and NADPH production by both G6PDH and 6PGDH was assayed spectrophotometrically to characterize pentose phosphate pathway activity. Finally, superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPX) and glutathione reductase (GR) activities were also assessed. As expected, MDA and carbonyl groups levels were higher at baseline and along the OGTT in insulin-resistant children. Both redox indicators showed an imbalance in favor of the oxidized forms along the OGTT in the insulin-resistant obese group. Additionally, the NADPH synthesis, as well as GR activity, were decreased. H
O
removing enzyme activities were depleted at baseline in both obese groups, although after sugar intake only metabolically healthy obese participants were able to maintain their catalase activity. No change was detected in SOD activity between groups. Our results show that obese children with insulin resistance present higher levels of oxidative damage, blunted capacity to generate reducing power, and hampered function of key NADPH-dependent antioxidant enzymes.
Pregnancy-related disorders, including preeclampsia and gestational diabetes, are characterized by the presence of an adverse intrauterine milieu that may ultimately result in oxidative and ...nitrosative stress. This scenario may trigger uncontrolled production of reactive oxygen species (ROS) such as superoxide anion (O●−) and reactive nitrogen species (RNS) such as nitric oxide (NO), along with an inactivation of antioxidant systems, which are associated with the occurrence of relevant changes in placental function through recognized redox post-translational modifications in key proteins. The general objective of this study was to assess the impact of a maternal obesogenic enviroment on the regulation of the placental nitroso-redox balance at the end of pregnancy. We measured oxidative damage markers—thiobarbituric acid-reacting substances (TBARS) and carbonyl groups (C=O) levels; nitrosative stress markers—inducible nitric oxide synthase, nitrosothiol groups, and nitrotyrosine residues levels; and the antioxidant biomarkers—catalase and superoxide dismutase (SOD) activity and expression, and total antioxidant capacity (TAC), in full-term placental villous from both pre-pregnancy normal weight and obese women, and with absence of metabolic complications throughout gestation. The results showed a decrease in C=O and TBARS levels in obese pregnancies. Although total SOD and catalase concentrations were shown to be increased, both activities were significantly downregulated in obese pregnancies, along with total antioxidant capacity. Inducible nitric oxide sintase levels were increased in the obese group compared to the lean group, accompanied by an increase in nitrotyrosine residues levels and lower levels of nitrosothiol groups in proteins such as ERK1/2. These findings reveal a reduction in oxidative damage, accompanied by a decline in antioxidant response, and an increase via NO-mediated nitrative stress in placental tissue from metabolically healthy pregnancies with obesity. All this plausibly points to a placental adaptation of the affected antioxidant response towards a NO-induced alternative pathway, through changes in the ROS/RNS balance, in order to reduce oxidative damage and preserve placental function in pregnancy.
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