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Studies concerning oxidative stress (OxE) parameters have increased, mainly because of its important role in cardiovascular diseases and diabetes complications. The main objective of this study was to evaluate iron nutrition status and oxidative stress parameters in subjects that had developed metabolic syndrome (MetS). Subjects from the Research Program of Risk Factors for Cardiovascular Disease (n = 155) were studied (ages ranging from 45 to 65 years old) and classified according to the Adult Treatment Panel III criterion. A blood sample was taken after a 12-h fasting period, and basal glucose, insulin, thiobarbituric acid reactive substances (TBARS), oxidized LDL (oxLDL), heme oxygenase (HO) activity, lipid profile, and iron nutrition status were determined. Eighty-five subjects were classified as MetS, and 70 non-MetS. Individuals with MetS showed higher Fe storage (high levels of ferritin, total body iron and low transferrin receptor), oxLDL, TBARS, and homeostatic model assessment for insulin resistance levels. The MetS group showed high levels of oxidative stress parameters (HO activity, oxLDL, and TBARS). The presence of MetS showed an association with LDL oxidation risk (multiple lineal regression according to sex and age, p < 0.001). High levels of triglycerides (p < 0.001) and waist circumference (p < 0.012) were associated with oxLDL levels, as well as an association between TBARS and oxLDL with ferritin levels. Through logistic regression analyses, the highest quartile of ferritin was associated with a threefold risk of developing MetS compared to the lowest quartile; also, TBARS showed a 21-fold risk for the development of MetS. Finally, elevated levels of oxidative stress parameters such us oxLDL, TBARS, HO, and Fe storage were associated to MetS.

Adipose tissue secretes numerous pro-inflammatory cytokines, such as interleukin (IL)-6 and tumor necrosis factor (TNF)-α that can lead to insulin resistance (IR). In the liver, both IL-6 and TNF-α induce IR by inhibiting phosphorylation or ubiquitination of IRS1. In IR development, Fe is a risk factor in type-2 diabetes development. We studied the expression of genes related to inflammation, hypoxia, and mitochondrial function in hepatic (HepG2) and adipose (3T3-L1) cells. HepG2 and 3T3-L1 cells were incubated with 20 μM Fe, 40 μM Fe, or 40 μM Fe/20 mM glucose for 7 days and then challenged with 20 ng/ml IL-6 and/or 100 μM CoCl(2) for 20 h. We measured intracellular Fe levels and the relative expression of hepcidin, NF-κB, IL-6, TNF-α, hypoxia inducible factor 1α (HIF-1α), and mitofusin 2 (Mfn-2) mRNA using qRT-PCR. The intracellular Fe concentration in HepG2 cells did not change with 20 or 40 μM Fe. However, levels were decreased with Fe/glucose and IL-6 and/or CoCl(2). 3T3-L1 cells showed an increase in intracellular Fe with high Fe plus either IL-6 or CoCl(2). HepG2 cells incubated with 40 μM Fe alone or Fe/glucose and challenged with IL-6 and/or CoCl(2) showed increased IL-6, NF-κB, and TNF-α mRNA expression and decreased mRNA expression of Mfn-2 in all experimental conditions. 3T3-L1 cells incubated with 40 μM Fe alone or Fe/glucose and challenged with IL-6 showed increased NF-κB mRNA expression and decreased Mfn-2 expression in all experimental conditions. Thus, high Fe, inflammation, and hypoxia trigger the expression of genes related to inflammation and Fe metabolism in HepG2 cells, in 3T3-L1 cells the same stimuli increased NF-kB and hepcidin expression.

Efecto de metformina sobre la expresión del factor de necrosis tumoral-a, los receptores Toll-like 2/4 y la PCR ultra sensible en sujetos obesos con diabetes tipo 2 RNA was isolated from these cells to measure expression of tumor necrosis factor-α (TNF-α), Interleukin-6 (IL-6), nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), Toll-Like Receptor 2/4 (TLR 2/4) and beta-2-microglobulin (B2M).Results: Thirty participants were studied. Of these, 16 subjects aged 54.4 ± 5.5 years were treated with metformin and 14 subjects aged 54.9 ± 6.4 years did not receive the drug. Participants receiving metformin had lower levels of hsCRP and lower mRNA relative abundance of TNF-α and TLR 2/4. There were no differences in glucose levels or lipid profile between both groups. Conclusions: Obese diabetic patients treated with metformin had lower levels of hsCRP expression of TNF-α and TLR 2/4, than their counterparts not receiving the drug. (Rev Med Chile 2012; 140: 1377-1382.

Calcium, phytic acid, polyphenols and fiber are major inhibitors of iron absorption and they could be found in excess in some diets, thereby altering or modifying the iron nutrition status. The purpose of this study is to evaluate the effect of calcium, tannic acid, phytic acid, and pectin over iron uptake, using an in vitro model of epithelial cells (Caco-2 cell line). Caco-2 cells were incubated with iron (10-30 μM) with or without CaCl2 (500 and 1,000 μM) for 24 h. Then, cells were challenged with phytic acid (50-150 μM); pectin (50-150 nM) or tannic acid (100-500 μM) for another 24 h. Finally, (55)Fe (10 μM) uptake was determined. Iron dialyzability was studied using an in vitro digestion method. Iron uptake in cells pre-incubated with 20 and 30 μM Fe was inhibited by CaCl2 (500 μM). Iron uptake decreased in cells cultured with tannic acid (300 μM) and CaCl2 (500-1,000 μM) (two-way ANOVA, p = 0.002). Phytic acid also decreased iron uptake mainly when cells were treated with CaCl2 (1,000 μM) (two-way ANOVA; p < 0.05). Pectin slightly decreased iron uptake (p = NS). Iron dialyzability decreased when iron was mixed with CaCl2 and phytic or tannic acid (T test p < 0.0001, for both) but not when mixed with pectin. Phytic acid combined with calcium is a strong iron uptake inhibitor. Pectin slightly decreased iron uptake with or without calcium. Tannic acid showed an unexpected behavior, inducing an increase on iron uptake, despite its low Fe dialyzability.

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