Modulation of Zinc Transporter Expressions by Additional Zinc in C2C12 Cells Cultured in a High Glucose Environment and in the Presence of Insulin or Interleukin-6.

Zn status has been related to various chronic diseases presenting oxidative stress and inflammation, such as type 2 diabetes. Zn supplementation has been suggested to be a potential coadjuvant in the management of this condition. Zn transporters constitute a key component in the maintenance of Zn homeostasis. Our aim was to evaluate the modulatory effect of additional Zn (10 or 100 µM; as a ZnSO4*7H20) on the mRNA relative expression of selected Zn transporters (ZnT1, ZnT5, ZnT7, ZIP6, ZIP7, ZIP10, ZIP14), in myoblast (C2C12) cells cultured in normal (10 mM) and high glucose (30 mM), and in the absence or presence of insulin (1 nM), and interleukin-6 (IL-6; 5 nM) for 24 h. The main findings of our study were that in high glucose conditions in absence of insulin or IL-6, additional Zn increased ZnT1 and ZIP6, and decreased ZnT5 and ZIP7 expressions. However, this situation is modified by insulin, where incremental Zn induced increased expressions of ZnT1, ZnT5, and all the ZIP transporters studied. In high glucose conditions and in the presence of IL-6, additional Zn caused increased expressions of ZnT7, ZIP7, and ZIP14, compared with results in the absence of IL-6. This study provides preliminary evidence for the differential expression of selected Zn transporters in C2C12 cells subjected to high glucose and incremental Zn, suggesting that important changes in intracellular Zn distribution take place in response to inflammatory and high-insulin environments. Further study is necessary to understand the implications of these findings.

Vitamin D status and obesity in children from Chile.

BACKGROUND: Vitamin D [25(OH)D] is essential for normal bone development and maintenance. Furthermore, its deficiency has been associated with obesity, cardiovascular diseases, insulin resistance, autoimmune diseases, and certain cancers. OBJECTIVE: To determine the incidence of serum 25(OH)D deficiency (<20 ng/ml) among apparently healthy Chilean children (4-14 years old) from three Chilean geographic areas during May-September 2018. MATERIALS AND METHODS: Serum 25(OH)D levels were measured by a competitive protein-binding ELISA assay in 1134 children, and correlations between serum 25(OH)D levels, BMI, and geographic area were calculated. Individuals were grouped according to their serum 25-hydroxyvitamin D levels (ng/ml): severe deficiency: <5; moderate deficiency: 5-10.9; mild deficiency: 11-20.9; insufficiency: 21-29.9 and sufficiency: 30-100. RESULTS: We found 80.4% of children had serum 25(OH)D deficiency, with 1.7% severe, 24.6% moderate, and 54.1% mild. In the three cities, the percentage of serum 25(OH)D deficit was increased when comparing overweight or obesity with a healthy weight. Additionally, an interaction effect was observed between geographic area, nutritional status, and serum 25(OH)D levels using the factorial ANOVA test (p = 0.038). In Antofagasta, there were more overweight children and also a higher percentage of children with VitD deficiency (<30 ng/ml) compared to Santiago or Concepción. CONCLUSION: This study revealed a high prevalence of serum 25(OH)D deficiency in children between 4 and 14 years old in Chile (80.4%) during May-September 2018. Obese and overweight children had the highest prevalence of serum 25(OH)D deficiency.

Zinc Modulates the Response to Apoptosis in an In Vitro Model with High Glucose and Inflammatory Stimuli in C2C12 Cells.

Apoptosis is programmed cell death and its alteration is related to cancer, neurologic, autoimmune, and chronic diseases. A number of factors can affect this process. The aim of this paper is to study the effect of supplemental zinc on apoptosis-related genes in C2C12 myoblast cells after being challenged with a series of stimuli, such as high glucose, insulin, and an inflammatory agent. C2C12 myoblast cells were cultured for 24 h with zinc (Zn) (ZnSO4) 10 or 100 µM and/or glucose 10 or 30 mM. In addition to these stimuli, the cells were challenged with insulin 1 nM or interleukin-6 (IL-6) 5 nM. The mRNA expression of proapoptotic genes caspase 3 and Fas, the antiapoptotic genes, Xiap and Bcl-xL and the ratio of pro-/antiapoptotic genes Bax/Bcl-2, were determined by qRT-PCR. The expression of caspase-3 gene was significantly increased in the presence of the combination high Zn/high glucose with and without the presence of insulin and IL6 in the culture medium Fas expression instead, showed uneven responses. The expression of Bcl-xL and Xiap was increased in most conditions by having high Zn in the medium regardless of the presence of insulin or IL6. Bax/Bcl2 ratio was decreased in the presence of high Zn. Zn was able to stimulate the expression of antiapoptotic genes. This effect was specially noted in high-glucose conditions with and without the presence of insulin. This effect is partially overridden by the presence of an inflammatory agent such as IL-6.

Short repeats in the heme oxygenase 1 gene promoter is associated with increased levels of inflammation, ferritin and higher risk of type-2 diabetes mellitus.

OBJECTIVE: We evaluated the relationship between the HO1 genotype, ferritin levels and the risk of type-2 diabetes and inflammation. RESEARCH METHODS: Eight hundred thirty-five individuals were evaluated and classified according to their nutritional status and the presence of type-2 diabetes: 153 overweight (OW); 62 obese (OB); 55 type-2 diabetes mellitus (DM); 202 OWDM; 239 OBDM and 124 controls (C). We studied biochemical (glycemia, insulin, lipid profile, liver enzyme, creatinine, hsCRP), hematological (hemoglobin, free erythrocyte protoporphyrin, transferrin receptor and serum Fe and ferritin) and oxidative stress (SOD, GHS and TBARS) parameters. We determined heme oxygenase activity and the (GT)n polymorphism in its gene promoter. RESULTS: Individuals with diabetes, independent of nutritional status, showed high levels of ferritin and HO activity compared to control subjects. Allelic frequency was not different between the groups (Chi(2), NS) however, genotypes were different (Chi(2), P<0.001). The SS (short-short) genotype was higher in all DM individuals compared to controls and MM was higher in controls. SM (short-medium) genotype was an independent risk factor for DM in logistic regression analysis. We observed high risk for type-2 diabetes mellitus in the presence of SM genotype and high levels of ferritin (OR adjusted: 2.7; 1.9-3.6; p<0.001; compared to control group). It was also significantly related to inflammation. CONCLUSION: The SM genotype in HO1 gene promoter and ferritin levels were associated with higher risk for type-2 diabetes and for having a higher marker of inflammation, which is the main risk factor for the development of chronic diseases.

Association between ferritin and hepcidin levels and inflammatory status in patients with type 2 diabetes mellitus and obesity.

OBJECTIVE: The aim of this study was to determine the association between iron parameters and inflammation in obese individuals with and without type 2 diabetes mellitus (T2DM). METHODS: We studied 132 obese individuals (OB), 60 individuals with T2DM, 106 obese individuals with T2DM (T2DOB), and 146 controls (C). All of were men aged >30 y. Biochemical, iron nutrition, and oxidative stress parameters were determined. Peripheral mononuclear cells were isolated and total RNA was extracted to quantify tumor necrosis factor (TNF)-α, nuclear factor (NF)-κB, interleukin (IL)-6, toll-like receptor (TLR)-2/4 and hepcidin by quantitative reverse transcription polymerase chain reaction. RESULTS: OB, T2DM, and T2DOB individuals had higher ferritin, retinol-binding protein 4, and thiobarbituric acid reactive substance (TBAR) levels than controls. T2DOB and T2DM individuals showed high high-sensitivity C-reactive protein (hsCRP) levels and OB with and without T2DM had elevated levels of serum hepcidin. Heme oxygenase activity was high in OB and T2DM and there were no differences observed in superoxide dismutase and glutathione parameters. A correlation between TBARS and ferritin in T2DOB was observed (r = 0.31; P < 0.006). Multiple linear regression analysis showed an association between diabetes and obesity with ferritin, TBARS, and hsCRP levels. The upper quartiles of ferritin, TBARS and hepcidin showed an adjusted odd ratio for T2DM of 1.782, 2.250, and 4.370, respectively. TNF-α, IL-6, hepcidin, NF-κB, TLR-2/4 mRNA abundances were increased in T2DM and T2DOB. CONCLUSION: Elevated hsCRP and hepcidin levels, and increased gene expression of TNF-α, IL-6, NF-κB, and TLR-2/4 in patients with diabetes, obesity, or both exacerbate and perpetuate the insulin resistance and inflammatory state.

Effects of high iron and glucose concentrations over the relative expression of Bcl2, Bax, and Mfn2 in MIN6 cells.

Type 2 diabetes is characterized by hyperglycemia and oxidative stress. Hyperglycemia is linked to mitochondrial dysfunction and reduced ß-cell mass due to the reduced expression of genes such as Mfn2 as well as the participation of the Bcl2 gene family, responsible for increased apoptosis. The purpose of this study was to describe the effect of different iron and/or glucose concentrations over Mfn2, Bax, and Bcl2 expressions in a ß-pancreatic cell line (MIN6 cells). MIN6 cells were pre-incubated with different iron and/or glucose concentrations, and the relative mRNA abundance of the Bcl2/Bax ratio and of Mfn2 genes was measured by qRT-PCR. Heme oxygenase (HO) activity, iron uptake, superoxide dismutase activity, and glutathione content were also determined. The Bcl2/Bax ratio increased and Mfn2 expression decreased in MIN6 cells after glucose stimulation. These effects were higher when glucose and iron were incubated together. Additionally, treatment with glucose/iron showed a higher HO activity. Our study revealed that high glucose/Fe concentrations in MIN6 cells induced an increase of the Bcl2/Bax ratio, an indicator of increased cell apoptosis.