Carmela Santangelo

Cyanidin-3- O -β-Glucoside and Protocatechuic Acid Exert Insulin-Like Effects by Upregulating PPARγ Activity in Human Omental Adipocytes

OBJECTIVE Insulin resistance (IR) represents an independent risk factor for metabolic, cardiovascular, and neoplastic disorders. Preventing/attenuating IR is a major objective to be reached to preserve population health. Because many insulin-sensitizing drugs have shown unwanted side effects, active harmless compounds are sought after. Dietary anthocyanins have been demonstrated to ameliorate hyperglycemia and insulin sensitivity. This study aimed at investigating whether cyanidin-3-O-β-glucoside (C3G) and its metabolite protocatechuic acid (PCA) might have a role in glucose transport activation in human omental adipocytes and 3T3-L1 cells. RESEARCH DESIGN AND METHODS In cells treated with 50 µmol/L C3G and 100 µmol/L PCA, [3H]-2-deoxyglucose uptake, GLUT4 translocation by immunoblotting, adiponectin secretion, and peroxisome proliferator–activated receptor-γ (PPARγ) activation by enzyme-linked immunosorbent assay kits were evaluated. Parallel experiments were carried out in murine adipocyte 3T3-L1. To define the role of PPARγ in modulating polyphenol effects, small interfering RNA technique and PPARγ antagonist were used to inhibit transcription factor activity. RESULTS C3G and PCA increased adipocyte glucose uptake (P < 0.05) and GLUT4 membrane translocation (P < 0.01). Significant increases (P < 0.05) in nuclear PPARγ activity, as well as in adiponectin and GLUT4 expressions (P < 0.01), were also shown. It is interesting that PPARγ inhibition counteracted the polyphenol-induced adiponectin and GLUT4 upregulations, suggesting a direct involvement of PPARγ in this process. CONCLUSIONS Our study provides evidence that C3G and PCA might exert insulin-like activities by PPARγ activation, evidencing a causal relationship between this transcription factor and adiponectin and GLUT4 upregulation. Dietary polyphenols could be included in the preventive/therapeutic armory against pathological conditions associated with IR.

Nitric oxide synthases in normal and benign hyperplastic human prostate: Immunohistochemistry and molecular biology

The expression of nitric oxide synthase (NOS) isoforms has been investigated in normal (three subjects) and benign hyperplastic prostate (ten patients) by immunohistochemistry and reverse transcriptase‐polymerase chain reaction (RT‐PCR). The inducible NOS (iNOS or NOS‐2) is not detected in normal prostate, while it is expressed in the prostate of all benign prostatic hyperplasia (BPH) patients, even in the absence of prostatitis or systemic signs of an inflammatory condition. This suggests that sex hormones may be involved in iNOS induction and that there may be a role for NO in the pathogenesis of BPH. Constitutive NOSs (nNOS and eNOS) are expressed in both normal and hyperplastic prostate and are co‐expressed in epithelial cells. eNOS, however, is present mainly in the basal layer cells; nNOS seems abundantly expressed in the more superficial cells of the affected prostate. This indicates that the switching between the two constitutive isoforms may be part of the usual process of cell differentiation from the basal to the secretory layer of the epithelium. Copyright

Predominant role of obesity/insulin resistance in oxidative stress development

Eur J Clin Invest 2012; 42 (1): 70–78

Upregulation of mitochondrial peripheral benzodiazepine receptor expression by cytokine‐induced damage of human pancreatic islets

Cytokines produced by immune system cells infiltrating pancreatic islets are candidate mediators of islet beta‐cell destruction in autoimmune insulin‐dependent diabetes mellitus. After 72 h exposure of human pancreatic islets to a cytotoxic cytokine combination of interleukin 1 beta (50 U/ml), tumor necrosis factor alpha (1,000 U/ml), and interferon gamma (1,000 U/ml), an increase of cell death vs. control islets was demonstrated by TUNEL and cell death detection ELISA method. Islet death was associated with apoptosis and mitochondrial swelling as evidenced by electron microscopy. This effect was correlated with a marked decrease of Bcl‐2 mRNA expression (without any major change of Bax mRNA) and a marked increase of inducible nitric oxide synthase mRNA. Since peripheral benzodiazepine receptors constitute the aspecific mitochondrial permeability transition pore, and that it has been suggested to be involved in cytokine‐induced cell death, we evaluated the effects of the cytotoxic cytokines on PBR density and mRNA expression. We demonstrated that cytokine treatment of human islets induced an increase of maximum density of 3H1‐(2‐chlorophenyl‐N‐methyl‐1‐methylpropyl)‐3‐ isoquinolinecarboxamide binding sites, (5,110 ± 193 vs. 3,421 ± 336 fmol/mg proteins, P < 0.05) with no significant change in the affinity constant value (9.45 ± 0.869 vs. 8.7 ± 1.159 nM). Moreover, an increase of the expression of peripheral benzodiazepine receptor mRNA was observed, suggesting an increased transcription from the coding gene. These results suggest a possible role of peripheral benzodiazepine receptors in the organism response to tissue damage associated with inflammatory mediator production. J. Cell. Biochem. 84: 636–644, 2002.

Hormonal regulation of cytokine release by human fetal membranes at term gestation: effects of oxytocin, hydrocortisone and progesterone on tumour necrosis factor-α and transforming growth factor-β 1 output

Inflammatory cytokines can play an important role in the biomolecular processes leading to labour by regulating prostaglandin production in intrauterine tissues. In the setting of intrauterine infection, an increased production of these cytokines by placenta, decidua and fetal membranes occurs and is responsible for the onset and maintenance of preterm labour. However, the factors involved in the control of cytokine release by these tissues in normal pregnancy at term are still largely unknown. We investigated the possibility that the synthesis and release of tumour necrosis factor-alpha (TNF-alpha) and transforming growth factor-beta1 (TGF-beta1) by human fetal membranes at term gestation is regulated by several hormones potentially involved either in the maintenance of pregnancy or in the parturitional process. In the present study, the effects of hydrocortisone, progesterone and oxytocin on TNF-alpha and TGF-beta1 release by explants of fetal membranes at term gestation were evaluated. Reverse transcriptase-polymerase chain reaction (RT-PCR) was used to assess the effect of the above hormones on mRNA expression; TNF-alpha and TGF-beta1 release in culture medium was quantitifed by ELISA assays. Results show that both tissue mRNA expression for TNF-alpha and TNF-alpha release in culture medium were significantly increased by oxytocin, but not by hydrocortisone and progesterone. On the contrary, all the hormones tested increased both tissue TGF-beta1 mRNA expression and release in culture medium. These findings suggest that TNF-alpha and TGF-beta1 production by human fetal membranes in uncomplicated pregnancy at term is selectively modulated by oxytocin, hydrocortisone and progesterone.

ω3-PUFAs Exert Anti-Inflammatory Activity in Visceral Adipocytes from Colorectal Cancer Patients

Objective The aim of this study was to correlate specific fatty acid profiles of visceral white adipose tissue (WAT) with inflammatory signatures potentially associated with colorectal cancer (CRC). Methods Human adipocytes were isolated from biopsies of visceral WAT from 24 subjects subdivided in four groups: normal-weight (BMI 22.0-24.9 Kg/m2) and over-weight/obese (BMI 26.0-40.0 Kg/m2), affected or not by CRC. To define whether obesity and/or CRC affect the inflammatory status of WAT, the activation of the pro-inflammatory STAT3 and the anti-inflammatory PPARγ transcription factors as well as the expression of adiponectin were analyzed by immunoblotting in adipocytes isolated from each group of subjects. Furthermore, to evaluate whether differences in inflammatory WAT environment correlate with specific fatty acid profiles, gas-chromatographic analysis was carried out on WAT collected from all subject categories. Finally, the effect of the ω3 docosahexaenoic acid treatment on the balance between pro- and anti-inflammatory factors in adipocytes was also evaluated. Results We provide the first evidence for the existence of a pro-inflammatory environment in WAT of CRC patients, as assessed by the up-regulation of STAT3, and the concomitant decrease of PPARγ and adiponectin with respect to healthy subjects. WAT inflammatory status was independent of obesity degree but correlated with a decreased ω3-/ω6-polyunsaturated fatty acid ratio. These observations suggested that qualitative changes, other than quantitative ones, in WAT fatty acid may influence tissue dysfunctions potentially linked to inflammatory conditions. This hypothesis was further supported by the finding that adipocyte treatment with docosahexaenoic acid restored the equilibrium between STAT3 and PPARγ. Conclusion Our results suggest that adipocyte dysfunctions occur in CRC patients creating a pro-inflammatory environment that might influence cancer development. Furthermore, the protective potential of docosahexaenoic acid in re-establishing the equilibrium between pro- and anti-inflammatory factors might represent a useful tool for preventive and therapeutic strategies.

Management of reproduction and pregnancy complications in maternal obesity: Which role for dietary polyphenols?

Obesity is a global and dramatic public health problem; maternal obesity represents one of the main risk factors of infertility and pregnancy complications as it is associated with adverse maternal and offspring outcomes. In the last few years, adipose tissue dysfunction associated with altered adipocytokine secretion has been suggested to play a critical role in all the phases of reproductive process. Obesity is a nutrition‐related disorder. In this regard, dietary intervention strategies, such as high intake of fruit and vegetables, have shown significant effects in both preserving health and counteracting obesity‐associated diseases. Evidence has been provided that polyphenols, important constituents of plant‐derived food, can influence developmental program of oocyte and embryo, as well as pregnancy progression by modulating several cellular pathways. This review will examine the controversial results so far obtained on adipocytokine involvement in fertility impairment and pregnancy complications. Furthermore, the different effects exerted by polyphenols on oocyte, embryo, and pregnancy development will be also taken in account.

Effects of prolonged exposure to pancreatic glucagon on the function, antigenicity and survival of isolated human islets.

Certain clinical conditions are associated with inappropriately high levels of circulating glucagon. To date, little information is available about the direct effects of prolonged exposure of human islet cells to pancreatic glucagon. In the present study we evaluated the function, antigenicity and survival of human islets exposed for 24 h to human pancreatic glucagon.

Could gestational diabetes mellitus be managed through dietary bioactive compounds? Current knowledge and future perspectives

Gestational diabetes mellitus (GDM) is a serious problem growing worldwide that needs to be addressed with urgency in consideration of the resulting severe complications for both mother and fetus. Growing evidence indicates that a healthy diet rich in fruit, vegetables, nuts, extra-virgin olive oil and fish has beneficial effects in both the prevention and management of several human diseases and metabolic disorders. In this review, we discuss the latest data concerning the effects of dietary bioactive compounds such as polyphenols and PUFA on the molecular mechanisms regulating glucose homoeostasis. Several studies, mostly based on in vitro and animal models, indicate that dietary polyphenols, mainly flavonoids, positively modulate the insulin signalling pathway by attenuating hyperglycaemia and insulin resistance, reducing inflammatory adipokines, and modifying microRNA (miRNA) profiles. Very few data about the influence of dietary exposure on GDM outcomes are available, although this approach deserves careful consideration. Further investigation, which includes exploring the ‘omics’ world, is needed to better understand the complex interaction between dietary compounds and GDM.

Effect of protocatechuic acid on insulin responsiveness and inflammation in visceral adipose tissue from obese individuals: possible role for PTP1B

Background/ObjectivesThe occurrence of chronic inflammation in visceral adipose tissue (VAT) in obese subjects precipitates the development of insulin resistance and type 2 diabetes (T2D). Anthocyanins and their main metabolite protocatechuic acid (PCA) have been demonstrated to stimulate insulin signaling in human adipocytes. The aim of this study was to investigate whether PCA is able to modulate insulin responsiveness and inflammation in VAT from obese (OB) and normal weight (NW) subjects.Subjects / MethodsVATs obtained from NW and OB subjects were incubated or not (control) with 100 μM PCA for 24 h. After incubation, tissues untreated and treated with PCA were acutely stimulated with insulin (20 nM, 20 min). PTP1B, p65 NF-κB, phospho-p65 NF-κB, IRS-1, IRβ, Akt, GLUT4 as well as basal and insulin-stimulated Tyr-IRS-1 and Ser-Akt phosphorylations were assessed by Western blotting in NW- and OB-VAT. Samples were assessed for PTP1B activity and adipocytokine secretion.ResultsPCA restored insulin-induced phosphorylation in OB-VAT by increasing phospho-Tyr-IRS-1 and phospho-Ser-Akt after insulin stimulation as observed in NW-VAT (p < 0.05). PTP1B activity was lower in OB-VAT treated with PCA with respect to untreated (p < 0.05). Compared to non-treated tissues, PCA reduced phospho-p65 NF-κB and IL-6 in OB-VAT, and IL-1β in NW-VAT (p < 0.05); and increased adiponectin secretion in NW-VAT (p < 0.05).ConclusionPCA restores the insulin responsiveness of OB-VAT by increasing IRS-1 and Akt phosphorylation which could be related with the lower PTP1B activity found in PCA-treated OB-VAT. Furthermore, PCA diminishes inflammation in VAT. These results support the beneficial role of an anthocyanin-rich diet against inflammation and insulin resistance in obesity.