Diego F. Garcia-Diaz

The deleterious effect of cholesterol and protection by quercetin on mitochondrial bioenergetics of pancreatic β-cells, glycemic control and inflammation: In vitro and in vivo studies

Studying rats fed high cholesterol diet and a pancreatic β-cell line (Min6), we aimed to determine the mechanisms by which quercetin protects against cholesterol-induced pancreatic β-cell dysfunction and impairments in glycemic control. Quercetin prevented the increase in total plasma cholesterol, but only partially prevented the high cholesterol diet-induced alterations in lipid profile. Quercetin prevented cholesterol-induced decreases in pancreatic ATP levels and mitochondrial bioenergetic dysfunction in Min6 cells, including decreases in mitochondrial membrane potentials and coupling efficiency in the mitochondrial respiration (basal and maximal oxygen consumption rate (OCR), ATP-linked OCR and reserve capacity). Quercetin protected against cholesterol-induced apoptosis of Min6 cells by inhibiting caspase-3 and -9 activation and cytochrome c release. Quercetin prevented the cholesterol-induced decrease in antioxidant defence enzymes from pancreas (cytosolic and mitochondrial homogenates) and Min6 cells and the cholesterol-induced increase of cellular and mitochondrial oxidative status and lipid peroxidation. Quercetin counteracted the cholesterol-induced activation of the NFκB pathway in the pancreas and Min6 cells, normalizing the expression of pro-inflammatory cytokines. Quercetin inhibited the cholesterol-induced decrease in sirtuin 1 expression in the pancreas and pancreatic β-cells. Taken together, the anti-apoptotic, antioxidant and anti-inflammatory properties of quercetin, and its ability to protect and improve mitochondrial bioenergetic function are likely to contribute to its protective action against cholesterol-induced pancreatic β-cell dysfunction, thereby preserving glucose-stimulated insulin secretion (GSIS) and glycemic control. Specifically, the improvement of ATP-linked OCR and the reserve capacity are important mechanisms for protection of quercetin. In addition, the inhibition of the NFκB pathway is an important mechanism for the protection of quercetin against cytokine mediated cholesterol-induced glycemic control impairment. In summary, our data highlight cellular, molecular and bioenergetic mechanisms underlying quercetins protective effects on β-cells in vitro and in vivo, and provide a scientifically tested foundation upon which quercetin can be developed as a nutraceutical to preserve β-cell function.

Chilean Native Fruit Extracts Inhibit Inflammation Linked to the Pathogenic Interaction Between Adipocytes and Macrophages

Obesity is characterized by an increase in the infiltration of monocytes into the adipose tissue, causing an inflammatory condition associated with, for example, the development of insulin resistance. Thus, anti-inflammatory-based treatments could emerge as a novel and interesting approach. It has been reported that Chilean native fruits maqui (Aristotelia chilensis) and calafate (Berberis microphylla) present high contents of polyphenols, which are known for their antioxidant and anti-inflammatory properties. The aim of this study was to evaluate the ability of extracts of these fruits to block the pathogenic interaction between adipocytes and macrophages in vitro and to compare its effect with blueberry (Vaccinium corymbosum) extract treatment, which has been already described to possess several biomedical benefits. RAW264.7 macrophages were treated with 5 μg/mL lipopolysaccharides (LPS), with conditioned media (CM) from fully differentiated 3T3-L1 adipocytes, or in a coculture (CC) with 3T3-L1 adipocytes, in the presence or absence of 100 μM [total polyphenolic content] of each extract for 24 h. The gene expression and secretion profile of several inflammatory markers were evaluated. Nitric oxide secretion induced by LPS, CM, and CC was reduced by the presence of maqui (-12.2%, -45.6%, and -14.7%, respectively) and calafate (-27.6%, -43.9%, and -11.8%, respectively) extracts. Gene expression of inducible nitric oxide synthase and TNF-α was inhibited and of IL-10 was induced by maqui and calafate extract incubation. In conclusion, the extracts of these fruits present important inhibitory-like features over the inflammatory response of the interaction between adipocytes and macrophages, comprising a potential therapeutic tool against comorbidities associated with obesity development.

Vitamin C in the treatment and/or prevention of obesity.

Obesity has emerged as one of the major health threats worldwide. Moreover, an excessive body fat accumulation, which defines this disease, could lead to several associated clinical manifestations such as cardiovascular events, type 2 diabetes, inflammation, and some types of cancer. The appearance of these co-morbidities has been often related to an unbalanced oxidative stress. Therefore, antioxidant-based treatments could be considered as interesting approaches to possibly counteract obesity fat accumulation complications. In this context, it has been observed that vitamin C intake (ascorbic acid) is negatively associated with the occurrence of several conditions such as hypertension, gallbladder disease, stroke, cancers, and atherosclerosis, and also with the onset of obesity in humans and animals. Among the possible beneficial effects of ascorbic acid on obesity-related mechanisms, it has been suggested that this vitamin may: (a) modulate adipocyte lipolysis; (b) regulate the glucocorticoid release from adrenal glands; (c) inhibit glucose metabolism and leptin secretion on isolated adipocytes; (d) lead to an improvement in hyperglycemia and decrease glycosylation in obese-diabetic models; and (e) reduce the inflammatory response. Possibly, all these features could be related with the outstanding antioxidant characteristics of this vitamin. Thus, the present article reviews the up-to-date evidence regarding in vitro and in vivo effects of vitamin C in obesity and its co-morbidities.

PD-L1 gene polymorphisms and low serum level of PD-L1 protein are associated to type 1 diabetes in Chile

Type 1 diabetes (T1D) has a complex etiology in which genetic and environmental factors are involved, whose interactions have not yet been completely clarified. In this context, the role in PD‐1 pathway and its ligands 1 and 2 (PD‐L1 and PD‐L2) have been proposed as candidates in several autoimmune diseases. The aim of this work was to determine the allele and haplotype frequency of six gene polymorphisms of PD‐ligands (PD‐L1 and PD‐L2) in Chilean T1D patients and their effect on serum levels of PD‐L1 and autoantibody profile (GAD65 and IA2).

La metilación global del ADN y los niveles de homocisteína en plasma se encuentran disminuidos en pacientes con diabetes mellitus tipo 1

BACKGROUND The worldwide rise in the incidence of Type 1 Diabetes (T1D), and the concordance rate between monozygotic twins (50%), indicate a strong effect of the environment as an underlying factor of this disease. This process can occur throughout epigenetic modifications of gene expression such as DNA methylation, in which several nutrients participate as cofactors. AIM To determine DNA methylation status in T1D patients and if it is related to plasma levels of folates and homocysteine (Hcy). MATERIAL AND METHODS We obtained blood samples from 25 T1D patients aged 13.7 ± 5.9 years (11 males) and 25 healthy subjects aged 31.1 ± 7.8 years (16 males). DNA methylation was measured using a colorimetric kit in extracted DNA. Results are expressed as median (interquartile range). RESULTS Compared with healthy controls, T1D patients had lower global DNA methylation (0.85 (0.91) % and 1.25 (1.16) % respectively, p < 0.02) and Hcy levels (4.8 (1.1) µmol/L and 7.3 (1.4) µmol/L respectively p < 0.01). There were no differences in folate levels between groups. A significant association between folates and global DNA methylation status was observed in T1D patients (r = -0.564, p < 0.01) and healthy subjects (r = 0.440, p = 0.03). CONCLUSIONS TD1 patients had lower levels of Hcy and global DNA methylation. It is relevant to further investigate if this imbalance also induces epigenetic changes in a gene-specific manner, especially in key genes involved in T1D pathogenesis.The worldwide rise in the incidence of Type 1 Diabetes (T1D), and the concordance rate between monozygotic twins (50%), indicate a strong effect of the environment as an underlying factor of this disease. This process can occur throughout epigenetic modifications of gene expression such as DNA methylation, in which several nutrients participate as cofactors. Aim: To determine DNA methylation status in T1D patients and if it is related to plasma levels of folates and homocysteine (Hcy). Material and Methods: We obtained blood samples from 25 T1D patients aged 13.7 ± 5.9 years (11 males) and 25 healthy subjects aged 31.1 ± 7.8 years (16 males). DNA methylation was measured using a colorimetric kit in extracted DNA. Results are expressed as median (interquartile range). Results: Compared with healthy controls, T1D patients had lower global DNA methylation (0.85 (0.91) % and 1.25 (1.16) % respectively, p < 0.02) and Hcy levels (4.8 (1.1) µmol/L and 7.3 (1.4) µmol/L respectively p < 0.01). There were no differences in folate levels between groups. A significant association between folates and global DNA methylation status was observed in T1D patients (r = -0.564, p < 0.01) and healthy subjects (r = 0.440, p = 0.03). Conclusions: TD1 patients had lower levels of Hcy and global DNA methylation. It is relevant to further investigate if this imbalance also induces epigenetic changes in a gene-specific manner, especially in key genes involved in T1D pathogenesisBackground: The worldwide rise in the incidence of Type 1 Diabetes (T1D), and the concordance rate between monozygotic twins (50%), indicate a strong effect of the environment as an underlying factor of this disease. This process can occur throughout epigenetic modifications of gene expression such as DNA methylation, in which several nutrients participate as cofactors. Aim: To determine DNA methylation status in T1D patients and if it is related to plasma levels of folates and homocysteine (Hcy). Material and methods: We obtained blood samples from 25 T1D patients aged 13.7 ± 5.9 years (11 males) and 25 healthy subjects aged 31.1 ± 7.8 years (16 males). DNA methylation was measured using a colorimetric kit in extracted DNA. Results are expressed as median (interquartile range). Results: Compared with healthy controls, T1D patients had lower global DNA methylation (0.85 (0.91) % and 1.25 (1.16) % respectively, p<0.02) and Hcy levels (4.8 (1.1) µmol/L and 7.3 (1.4) µmol/L respectively p<0.01). There were no differences in folate levels between groups. A significant association between folates and global DNA methylation status was observed in T1D patients (r=-0.564, p<0.01) and healthy subjects (r=0.440, p=0.03). Conclusions: TD1 patients had lower levels of Hcy and global DNA methylation. It is relevant to further investigate if this imbalance also induces epigenetic changes in a gene-specific manner, especially in key genes involved in T1D pathogenesis.

Epigenetics in type 1 diabetes: TNFa gene promoter methylation status in Chilean patients with type 1 diabetes mellitus.

TNF-α is a pro-inflammatory cytokine that is involved in type 1 diabetes (T1D) pathogenesis. The TNFa gene is subject of epigenetic regulation in which folate and homocysteine are important molecules because they participate in the methionine cycle where the most important methyl group donor (S-adenosylmethionine) is formed. We investigated whether TNFa gene promoter methylation status in T1D patients was related to blood folate, homocysteine and TNF-α in a transversal case-control study. We studied T1D patients (n 25, mean=13·7 years) and healthy control subjects (n 25, mean=31·1 years), without T1D and/or other autoimmune diseases or direct family history of these diseases. A blood sample was obtained for determination of serum folate, plasma homocysteine and TNF-α concentrations. Whole blood was used for the extraction of DNA to determine the percentage of methylation by real-time PCR and melting-curve analysis. Results are expressed as means and standard deviations for parametric variables and as median (interquartile range) for non-parametric variables. T1D patients showed a higher TNFa gene promoter methylation (39·2 (sd 19·5) %) when compared with control subjects (25·4 (sd 13·7) %) (P=0·008). TNFa gene promoter methylation was positively associated only with homocysteine levels in T1D patients (r 0·55, P=0·007), but not in control subjects (r -0·122, P=0·872). To our knowledge, this is the first work that reports the methylation status of the TNFa gene promoter and its relationship with homocysteine metabolism in Chilean T1D patients without disease complications.

Estado nutricional y marcadores bioquímicos de deficiencia o exceso de micronutrientes en niños chilenos de 4 a 14 años de edad: una revisión crítica

UNLABELLED The prevalence of obesity in Chilean children has been increasing steadily for the last two decades. The first study to determine nutritional status and food intake in a representative sample of this population was carried out in 1960. Recently the National Food Consumption Survey (ENCA) carried out in 2012 was released by the Ministry of Health. However, this study did not include biochemical determinations of micronutrients which would allow a better diagnosis of nutritional status in children. OBJECTIVE to review the literature available from 2004 to 2014 in food intake and nutritional status in Chilean children aged 4 to 14 years. METHOD a total of 362 references published between 2004 and 2014 were obtained through searches in the databases PubMed, Lilacs, Embase and Scielo. From these, 40 articles were selected for a thorough review. RESULTS food intake by children is characterized by a high-energy intake, a low consumption of fruits and vegetables and a high consumption of bread. The ENCA showed that 95% of the Chilean population has a deficient diet. A high prevalence of obesity is observed from very early in life. There is a dearth of data available on plasma indicators of vitamin and mineral status since 1960, which would provide more reliable information on nutritional assessment. CONCLUSION It is imperative to implement a representative nutrition survey of children in Chile that includes biochemical indicators to get reliable information in order to develop strategies aimed to correct micronutrient malnutrition from excess or deficiency.

Expression of miR-155, miR-146a, and miR-326 in T1D patients from Chile: relationship with autoimmunity and inflammatory markers

Objective The aim of this research was to analyze the expression profile of miR-155, miR-146a, and miR-326 in peripheral blood mononuclear cells (PBMC) of 47 patients with type 1 diabetes mellitus (T1D) and 39 control subjects, as well as the possible association with autoimmune or inflammatory markers. Subjects and methods Expression profile of miRs by means of qPCR using TaqMan probes. Autoantibodies and inflammatory markers by ELISA. Statistical analysis using bivariate correlation. Results The analysis of the results shows an increase in the expression of miR-155 in T1D patients in basal conditions compared to the controls (p < 0.001) and a decreased expression level of miR-326 (p < 0.01) and miR-146a (p < 0.05) compared T1D patients to the controls. miR-155 was the only miRs associated with autoinmmunity (ZnT8) and inflammatory status (vCAM). Conclusion Our data show a possible role of miR-155 related to autoimmunity and inflammation in Chilean patients with T1D.

La relación entre obesidad y complicaciones en el curso clínico de las enfermedades respiratorias virales en niños ¿un nuevo factor de riesgo a considerar?

Obesity has a high prevalence among children. On the other hand, acute respiratory infections especially of viral origin, are an important cause of morbidity and mortality in this age group. During the recent pandemic of influenza A (H1N1) virus, obesity was identified as a novel independent risk factor for severity multiple markers of the disease. We reviewed the evidence associating obesity with a worse course of respiratory diseases in children. Nine out of 40 retrieved articles, were chosen to be reviewed. We concluded that there is evidence suggesting that immunomodulatory effects of obesity could be considered as a novel risk factor. Thus, bearing in mind the drastic rise in obesity prevalence around the world and in Chile, and the latent possibility of new respiratory pandemics caused by viruses, studying the possible effect of obesity aggravating viral respiratory infections will become important.Obesity has a high prevalence among children. On the other hand, acute respiratory infections especially of viral origin, are an important cause of morbidity and mortality in this age group. During the recent pandemic of influenza A (H1N1) virus, obesity was identified as a novel independent risk factor for severity multiple markers of the disease. We reviewed the evidence associating obesity with a worse course of respiratory diseases in children. Nine out of 40 retrieved articles, were chosen to be reviewed. We concluded that there is evidence suggesting that immunomodulatory effects of obesity could be considered as a novel risk factor. Thus, bearing in mind the drastic rise in obesity prevalence around the world and in Chile, and the latent possibility of new respiratory pandemics caused by viruses, studying the possible effect of obesity aggravating viral respiratory infections will become important.