Identification and Validation of miR-222-3p and miR-409-3p as Plasma Biomarkers in Gestational Diabetes Mellitus Sharing Validated Target Genes Involved in Metabolic Homeostasis.

Gestational diabetes mellitus (GDM) causes both maternal and fetal adverse outcomes. The deregulation of microRNAs (miRNAs) in GDM suggests their involvement in GDM pathogenesis and complications. Exosomes are extracellular vesicles (EVs) of endosomal origin, released via exocytosis into the extracellular compartment. Through EVs, miRNAs are delivered in distant target cells and are able to affect gene expression. In this study, miRNA expression was analyzed to find new miRNAs that could improve GDM classification and molecular characterization. MiRNA were profiled in total plasma and EVs in GDM patients and normal glucose tolerance (NGT) women. Samples were collected at third trimester of gestation from two diabetes centers. MiRNA expression was profiled in a discovery cohort using the multiplexed NanoString nCounter Human v3 miRNA. Validation analysis was performed in a second independent cohort using RT-qPCR. A set of miRNAs resulted to be differentially expressed (DE) in total plasma and EVs in GDM. Among them, total plasma miR-222-3p and miR-409-3p were validated in the independent cohort. MiR-222-3p levels correlated with fasting plasma glucose (FPG) (p < 0.001) and birth weight (p = 0.012), whereas miR-409-3p expression correlated with FPG (p < 0.001) and inversely with gestational age (p = 0.001). The major validated target genes of the deregulated miRNAs were consistently linked to type 2 diabetes and GDM pathophysiology. MiR-222-3p and miR-409-3p are two circulating biomarkers that could improve GDM classification power and act in the context of the molecular events leading to the metabolic alterations observed in GDM.

The Impact of Ethnicity on Fetal and Maternal Outcomes of Gestational Diabetes.

Background and Objectives: The prevalence of gestational diabetes mellitus (GDM) significantly varies across different ethnic groups. In particular, Africans, Latinos, Asians and Pacific Islanders are the ethnic groups with the highest risk of GDM. The aim of this study was to evaluate the impact of ethnicity on pregnancy outcomes in GDM. Patients and Methods: n = 399 patients with GDM were enrolled, n = 76 patients of high-risk ethnicity (HR-GDM), and n = 323 of low-risk ethnicity (LR-GDM). Clinical and biochemical parameters were collected during pregnancy until delivery. Fetal and maternal short-term outcomes were evaluated. Results: HR-GDM had significantly higher values of glycosylated hemoglobin checked at 26−29 weeks of gestation (p < 0.001). Gestational age at delivery was significantly lower in HR-GDM (p = 0.03). The prevalence of impaired fetal growth was significantly higher in HR-GDM than LR-GDM (p = 0.009). In logistic regression analysis, the likelihood of impaired fetal growth was seven times higher in HR-GDM than in LR-GDM, after adjustment for pre-pregnancy BMI and gestational weight gain (OR = 7.1 [2.0−25.7] 95% CI, p = 0.003). Conclusions: HR-GDM had worse pregnancy outcomes compared with LR-GDM. An ethnicity-tailored clinical approach might be effective in reducing adverse outcomes in GDM.

Non-Coding RNA: Role in Gestational Diabetes Pathophysiology and Complications.

Gestational Diabetes Mellitus (GDM) is defined as glucose intolerance that develops in the second or third trimester of pregnancy. GDM can lead to short-term and long-term complications both in the mother and in the offspring. Diagnosing and treating this condition is therefore of great importance to avoid poor pregnancy outcomes. There is increasing interest in finding new markers with potential diagnostic, prognostic and therapeutic utility in GDM. Non-coding RNAs (ncRNAs), including microRNAs, long non-coding RNAs and circular RNAs, are critically involved in metabolic processes and their dysregulated expression has been reported in several pathological contexts. The aberrant expression of several circulating or placenta-related ncRNAs has been linked to insulin resistance and ß-cell dysfunction, the key pathophysiological features of GDM. Furthermore, significant associations between altered ncRNA profiles and GDM-related complications, such as macrosomia or trophoblast dysfunction, have been observed. Remarkably, the deregulation of ncRNAs, which might be linked to a detrimental intrauterine environment, can lead to changes in the expression of target genes in the offspring, possibly contributing to the development of long-term GDM-related complications, such as metabolic and cardiovascular diseases. In this review, all the recent findings on ncRNAs and GDM are summarized, particularly focusing on the molecular aspects and the pathophysiological implications of this complex relationship.

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

BACKGROUND/OBJECTIVES: The 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/METHODS: VATs 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, IRß, 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. RESULTS: PCA 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-1ß in NW-VAT (p < 0.05); and increased adiponectin secretion in NW-VAT (p < 0.05). CONCLUSION: PCA 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.

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.

Predominant role of obesity/insulin resistance in oxidative stress development.

BACKGROUND: Hyperlipidaemia, hyperglycaemia and hyperinsulinaemia, hallmarks of the postprandial state, have been also associated with increased oxidative stress and lipoprotein oxidation contributing to vascular injury and atherosclerosis. However, the specific links among metabolic disorders, postprandial state, insulin resistance and oxidative stress are still to be clarified. This study aimed at investigating the individual role played by obesity, insulin resistance and type 2 diabetes in the occurrence of fasting and postprandial oxidative stress. DESIGN: Biomarkers of oxidative stress [F2-isoprostanes and circulating oxidized low-density lipoproteins (LDL)], LDL oxidability (conjugated diene kinetic, thiobarbituric acid reactive substances (TBARs) formation and electronegativity increase) and antioxidant vitamins (ß-carotene, α-tocopherol and retinol) were evaluated at fasting and 6 h after a standard fat-rich meal in 10 obese diabetic (ObD), 11 obese and 11 normal-weight control men. Insulin sensitivity was evaluated by euglycaemic hyperinsulinaemic clamp. RESULTS: ObD and obese subjects, characterized by a similar level of adiposity and insulin resistance, showed higher urinary F2-isoprostanes and circulating oxidized LDL, an increased susceptibility to oxidation of plasma LDL (lower lag phase, higher TBARs formation, and higher relative electrophoretic mobility), and lower plasma content of ß-carotene and retinol than control subjects, both at fasting and after the test meal. CONCLUSIONS: Obesity and insulin resistance, more than type 2 diabetes, play the most relevant role in oxidative stress development. The correction of obesity and insulin resistance might be a useful strategy in counteracting systemic oxidative stress.

Dietary EVOO Polyphenols and Gut Microbiota Interaction: Are There Any Sex/Gender Influences?

Accumulating evidence indicates that regular consumption of extra virgin olive oil (EVOO), the main source of fat in the Mediterranean diet, is associated with beneficial health effects and a reduced risk of developing chronic degenerative disorders. The beneficial effects of EVOO can be attributed to its unique composition in monounsaturated fats and phenolic compounds that provide important antioxidant, anti-inflammatory, and immune-modulating activities. On the other hand, it is well known that the gut microbiota has several important roles in normal human physiology, and its composition can be influenced by a multitude of environmental and lifestyle factors, among which dietary components play a relevant role. In the last few years, the two-way interaction between polyphenols, including those in EVOO, and the gut microbiota, i.e., the modulation of the microbiota by polyphenols and that of polyphenol metabolism and bioavailability by the microbiota, has attracted growing attention, being potentially relevant to explain the final effects of polyphenols, as well as of the microbiota profile. Furthermore, sex and gender can affect dietary habits, polyphenol intake, and nutrient metabolism. Lastly, it has been recently suggested that differences in gut microbiota composition could be involved in the unequal incidence of metabolic diseases observed between women and men, due to sex-dependent effects on shaping gut microbiota profiles according to diet. This review summarizes the most recent studies on the relationship between EVOO polyphenols and the gut microbiota, taking into account possible influences of sex and gender in modulating such an interaction.

Significance of Sex Differences in ncRNAs Expression and Function in Pregnancy and Related Complications.

In the era of personalized medicine, fetal sex-specific research is of utmost importance for comprehending the mechanisms governing pregnancy and pregnancy-related complications. In recent times, noncoding RNAs (ncRNAs) have gained increasing attention as critical players in gene regulation and disease pathogenesis, and as candidate biomarkers in human diseases as well. Different types of ncRNAs, including microRNAs (miRNAs), piwi-interacting RNAs (piRNAs), long noncoding RNAs (lncRNAs), and circular RNAs (circRNAs), participate in every step of pregnancy progression, although studies taking into consideration fetal sex as a central variable are still limited. To date, most of the available data have been obtained investigating sex-specific placental miRNA expression. Several studies revealed that miRNAs regulate the (patho)-physiological processes in a sexually dimorphic manner, ensuring normal fetal development, successful pregnancy, and susceptibility to diseases. Moreover, the observation that ncRNA profiles differ according to cells, tissues, and developmental stages of pregnancy, along with the complex interactions among different types of ncRNAs in regulating gene expression, strongly indicates that more studies are needed to understand the role of sex-specific ncRNA in pregnancy and associated disorders.

Protocatechuic acid influences immune-metabolic changes in the adipose tissue of pregnant women with gestational diabetes mellitus.

Gestational diabetes mellitus (GDM) is associated with immune metabolic changes that increase women's risk of developing metabolic disorders later in life. Nutritional intervention is a crucial component in reducing the burden of these pathological features. We examined whether protocatechuic acid (PCA), a major metabolite of anthocyanins abundant in plant food, is able to exert insulin-mimetic activity and modulate inflammation in the visceral adipose tissue (VAT) obtained at delivery, from pregnant women with GDM or normal glucose tolerance (NGT). PCA stimulated glucose uptake in the VAT from both GDM and NGT women. This capability was associated with increased phosphorylation of p38 mitogen-activated protein kinase (p38MAPK), as further demonstrated by the inhibitory effect of SB203580, a p38MAPK inhibitor, on PCA-induced glucose uptake. The GDM-VAT expressed lower adiponectin levels and PCA stimulated adiponectin release in the NGT-VAT and, albeit to a lower extent, in the GDM-VAT. Higher levels of IL6 and TNFα were secreted by the GDM-VAT compared with the NGT one, and PCA had no effects on them. PCA reduced the overexpression of vasoactive intestinal peptide receptor 2 (VPAC2) in the GDM-VAT. Further studies are needed to establish whether and how anthocyanins and food rich in these compounds may contribute to prevent or delay metabolic disorders in women with GDM.

Curcumin: Could This Compound Be Useful in Pregnancy and Pregnancy-Related Complications?

Curcumin, the main polyphenol contained in turmeric root (Curcuma longa), has played a significant role in medicine for centuries. The growing interest in plant-derived substances has led to increased consumption of them also in pregnancy. The pleiotropic and multi-targeting actions of curcumin have made it very attractive as a health-promoting compound. In spite of the beneficial effects observed in various chronic diseases in humans, limited and fragmentary information is currently available about curcumin's effects on pregnancy and pregnancy-related complications. It is known that immune-metabolic alterations occurring during pregnancy have consequences on both maternal and fetal tissues, leading to short- and long-term complications. The reported anti-inflammatory, antioxidant, antitoxicant, neuroprotective, immunomodulatory, antiapoptotic, antiangiogenic, anti-hypertensive, and antidiabetic properties of curcumin appear to be encouraging, not only for the management of pregnancy-related disorders, including gestational diabetes mellitus (GDM), preeclampsia (PE), depression, preterm birth, and fetal growth disorders but also to contrast damage induced by natural and chemical toxic agents. The current review summarizes the latest data, mostly obtained from animal models and in vitro studies, on the impact of curcumin on the molecular mechanisms involved in pregnancy pathophysiology, with the aim to shed light on the possible beneficial and/or adverse effects of curcumin on pregnancy outcomes.

MicroRNA Modulation by Dietary Supplements in Obesity.

The prevalence of obesity has dramatically increased over the last decades. Weight loss obtained through diet and exercise leads to a significant decrease in morbidity and mortality. Recently, there has been growing interest in the possible beneficial effects of dietary supplements (DSs), including polyphenols, fatty acids, and other plant-derived substances, as adjuvants in the management of obesity and metabolic diseases. Specifically, polyphenols, widely spread in vegetables and fruits, significantly modulate adipose tissue activities, contrasting inflammation and improving insulin sensitivity in preclinical and clinical studies. Remarkably, polyphenols are involved in complex microRNA networks, which play crucial roles in metabolic processes. The administration of different polyphenols and other plant-derived compounds led to significant changes in the microRNA expression profile in peripheral tissues in a growing number of preclinical studies. In particular, these compounds were able to revert obesity-induced microRNA dysregulation, leading to the inhibition of adipogenesis and the induction of weight loss. Furthermore, through microRNA modulation, they attenuated key metabolic alterations, including insulin resistance and lipid anomalies, in animal models of obesity. Some of them were also able to reduce proinflammatory cytokines in adipose tissue. The aim of this review is to summarize current evidence about the effect of plant-derived DSs on microRNA expression in obesity.

Cross-talk between fetal membranes and visceral adipose tissue involves HMGB1-RAGE and VIP-VPAC2 pathways in human gestational diabetes mellitus.

AIMS: Gestational diabetes mellitus (GDM) is defined as glucose intolerance that is first diagnosed during pregnancy. Maternal adipose tissue and fetal membranes secrete various molecules that are relevant players in the pathogenesis of GDM. This pilot study aimed to examine whether the expression of the high mobility group box 1 protein (HMGB1) and its receptor for advanced glycation end products (RAGE), and the vasoactive intestinal peptide (VIP) and its receptors (VPAC-1,-2) were modified in pregnant women with GDM. METHODS: Fetal membranes (FMs), omental adipose tissue (VAT) explants, and serum samples were obtained from 12 women with GDM and 12 with normal glucose tolerance (NGT) at delivery. The expression of HMGB1, RAGE and VIP, VPAC-1,-2 was detected by Western Blotting in explants; circulating levels and "in vitro" release of HMGB1 and VIP were measured by ELISA tests. RESULTS: HMGB1 tissue expression was higher in FMs obtained from GDM women (p = 0.02) than in FMs from NGT women. VPAC2 (p = 0.03) and RAGE (p = 0.03) tissue expressions were significantly increased in VAT from GDM subjects. Only FMs of NGT released detectable levels of HMGB1, which was not observed in samples obtained from GDM. VAT of GDM released lower levels of VIP (p = 0.05) than NGT samples. CONCLUSIONS: This study indicates that a fine tuned regulation exists between FMs and VAT throughout pregnancy to maintain immune metabolic homeostasis. In GDM a balance between inflammatory and anti-inflammatory mediators has been observed. Further studies are needed to establish their exact role on fetal and maternal outcomes in GDM.

Oxidised LDL up-regulate CD36 expression by the Nrf2 pathway in 3T3-L1 preadipocytes.

The effect of oxLDL on CD36 expression has been assessed in preadipocytes induced to differentiate. Novel evidence is provided that oxLDL induce a peroxisome proliferator-activated receptor gamma-independent CD36 overexpression, by up-regulating nuclear factor erythroid 2 (NF-E2)-related factor 2 (Nrf2). The nuclear translocation of Nrf2 appeared to depend on PKC pathway activation. In adipocytes, the CD36 up-regulation may indicate a compensation mechanism to meet the demand of excess oxLDL and oxidised lipids in blood, reducing the risk of atherogenesis. Besides strengthening the hypothesis that oxLDL can contribute to the onset of insulin-resistance, data herein presented highlight the significance of oxLDL-induced CD36 overexpression within the cellular defence response.

Postprandial chylomicrons and adipose tissue lipoprotein lipase are altered in type 2 diabetes independently of obesity and whole-body insulin resistance.

BACKGROUND AND AIMS: Postprandial lipoprotein abnormalities in type 2 diabetes are associated with insulin resistance. The role of other diabetes-related factors is still not clear. The aim of this study is to differentiate the effects of whole-body insulin resistance, obesity, and type 2 diabetes on postprandial dyslipidaemia and lipoprotein lipase (LPL) in adipose tissue. METHODS AND RESULTS: Ten subjects with obesity and diabetes (OD), 11 with obesity alone (O), and 11 normal-weight controls (C) - males, aged 26-59 years, with fasting normo-triglyceridaemia underwent measurements of cholesterol, triglycerides, apo B-48 and apo B-100 concentrations in plasma lipoproteins separated by density gradient ultracentrifugation before and after a fat-rich meal. Fasting and postprandial (6h) LPL activity was determined in abdominal subcutaneous adipose tissue biopsy samples. Insulin sensitivity was measured by hyperinsulinaemic euglycaemic clamp. OD and O subjects had similar degrees of adiposity (BMI, waist circumference, fat mass) and insulin resistance (insulin stimulated glucose disposal and M/I). They also showed a similarly higher postprandial increase in large VLDL lipids (triglyceride incremental AUC 188+/-28 and 135+/-22 mg/dl.6h) than C (87+/-13 mg/dl.6h, M+/-SEM, p<0.05). OD had an increased chylomicron response compared to O (triglyceride incremental AUC 132+/-23 vs. 75+/-14 mg/dl.6h, p<0.05). OD had significantly lower fasting and postprandial adipose tissue heparin-releasable LPL activity than O and C. CONCLUSIONS: In insulin-resistant conditions of obesity, with and without diabetes, large VLDL are increased after a fat-rich meal. In addition, diabetic patients compared to obese subjects have an increased postprandial chylomicron response and a reduced adipose tissue LPL activity.

Modulatory effects of polyphenols on apoptosis induction: relevance for cancer prevention.

Polyphenols, occurring in fruit and vegetables, wine, tea, extra virgin olive oil, chocolate and other cocoa products, have been demonstrated to have clear antioxidant properties in vitro, and many of their biological actions have been attributed to their intrinsic reducing capabilities. However, it has become clear that, in complex biological systems, polyphenols exhibit several additional properties which are yet poorly understood. Apoptosis is a genetically controlled and evolutionarily conserved form of cell death of critical importance for the normal embryonic development and for the maintenance of tissue homeostasis in the adult organism. The malfunction of the death machinery may play a primary role in various pathological processes, since too little or too much apoptosis can lead to proliferative or degenerative diseases, respectively. Cancer cells are characterized by a deregulated proliferation, and/or an inability to undergo programmed cell death. A large body of evidence indicates that polyphenols can exert chemopreventive effects towards different organ specific cancers, affecting the overall process of carcinogenesis by several mechanisms: inhibition of DNA synthesis, modulation of ROS production, regulation of cell cycle arrest, modulation of survival/proliferation pathways. In addition, polyphenols can directly influence different points of the apoptotic process, and/or the expression of regulatory proteins. Although the bulk of data has been obtained in in vitro systems, a number of clinical studies suggesting a preventive and therapeutic effectiveness of polyphenols in vivo is available. However, a deeper knowledge of the underlying mechanisms responsible for the modulation of apoptosis by polyphenols, and their real effectiveness, is necessary in order to propose them as potential chemopreventive and chemotherapeutic candidates for cancer treatment.

Recent Evidence on the Role of Dietary PUFAs in Cancer Development and Prevention.

BACKGROUND: Scientific evidence has been accumulated about the effects of polyunsaturated fatty acids (PUFAs) on human health. The hypothesis that n-3 PUFAs might improve the efficiency of anticancer drugs has recently been considered. The role of n-6 PUFAs, in contrast, needs to be better assessed. However, the effective mechanisms of action of PUFAs have not been fully clarified yet. This review aims to report the most updated evidence on the role of n-6 and n-3 PUFAs in the development and treatment of human cancers, focusing on the potential mechanisms by which PUFAs exert their effects. METHODS: We undertook a structured search in PubMed on February 17th 2017 for peer-reviewed research articles published from 2013. The search syntax used was: PUFA or PUFAs and cancer. RESULTS: Contradictory results were found, most likely due to the genetic background, the different dietary sources used, the interaction among different nutrients, and the tumor subtypes. However, the more recent findings strongly support the use of n-3 PUFAs in cancer prevention and treatment. On the other hand, n-6 PUFAs are often associated with an increased risk of cancer, even if recently their beneficial effects have also been highlighted. CONCLUSION: N-3 PUFAs may represent a potential therapeutic agent contributing to treat at least some type of human cancers. However, studies with larger sample sizes and longer follow-up times are still needed. To increase the knowledge about how food and nutrition can improve human health it is advisable to deliver an open access nutritional database.

Anti-inflammatory Activity of Extra Virgin Olive Oil Polyphenols: Which Role in the Prevention and Treatment of Immune-Mediated Inflammatory Diseases?

BACKGROUND AND OBJECTIVE: Altered inflammatory response characterizes chronic immunemediated inflammatory diseases (IMID) such as rheumatoid arthritis, inflammatory bowel disease, multiple sclerosis, systemic lupus erythematosus, and psoriasis. Accumulating evidence indicates that regular consumption of extra virgin olive oil (EVOO), the main source of fat in the Mediterranean diet, is associated with a reduced risk of developing chronic degenerative disorders such as cardiovascular diseases, type 2 diabetes and cancer. The beneficial effects on health of EVOO have been attributed, besides to the monounsaturated fats content, to the presence of phenolic compounds that have antioxidant, anti-inflammatory and immunomodulatory properties. The purpose of this review is to provide an overview of the effects of EVOO polyphenols on IMID highlighting the potential mechanisms of action. METHODS: Scientific papers were found by searching in PubMed up to May 2017 using the following key words: rheumatoid arthritis, inflammatory bowel disease, multiple sclerosis, systemic lupus erythematosus, and psoriasis also in combination with EVOO, phenolic compounds, oleuropein, oleocantal, hydroxytyrosol,tyrosol and oleochantal. RESULTS: In vitro and in vivo studies indicate that EVOO and its polyphenols can improve diseases symptoms in IMID, by acting both at local and systemic levels and by modulating several molecular pathways. Nevertheless, there are not sufficient data to achieve specific nutritional guidelines. CONCLUSION: Further research is needed to evaluate the real contribution of EVOO and its phenolic compounds in modulating the IMID-associated inflammatory perturbations, in order to develop appropriate nutritional recommendations.

Hepatocyte growth factor protects rat RINm5F cell line against free fatty acid-induced apoptosis by counteracting oxidative stress.

Type 2 diabetes is characterized by peripheral insulin resistance, pancreatic beta-cells dysfunction, and decreased beta-cell mass with increased rate of apoptosis. Chronic exposure to high levels of free fatty acids (FFAs) has detrimental effects on beta-cell function and survival. FFAs have adverse effects on mitochondrial function, with a consequent increase in the production of reactive oxygen species. Hepatocyte growth factor (HGF) plays a critical role in promoting beta-cell survival. In the present study, we investigated whether HGF was capable of protecting beta-cells from death induced by prolonged exposure to FFAs. RINm5F cell line was cultured in the presence of FFAs (oleate:palmitate 2:1) for 72 h in order to induce apoptosis. Simultaneous administration of HGF and FFAs significantly suppressed the impaired insulin secretion and FFA-induced apoptosis. Specifically, HGF exerted its protective effect by counteracting: (i) the overproduction of either hydrogen peroxide and superoxide anion, (ii) the reduction of intracellular gamma-glutamylcysteinylglycine level, and (iii) the depolarization of mitochondrial membrane, induced by prolonged FFAs exposure. These effects appear to be mediated by bcl-2 and phosphatidylinositol 3 kinase (PI3K)/Akt pathways. Indeed, HGF increased mRNA and protein expression of bcl-2 downregulated by FFAs-treatment; moreover, pre-treatment with the specific PI3-kinase inhibitor LY294002, significantly abolished the protective effect of HGF. In conclusion, in rat insulin-producing RINm5F cells, HGF exerts its prosurvival effect by counteracting the increased intracellular oxidative stress and, consequently, by inhibiting apoptosis induced by chronic exposure to FFAs.

Tyrosol, the major extra virgin olive oil compound, restored intracellular antioxidant defences in spite of its weak antioxidative effectiveness.

BACKGROUND AND AIM: Extra virgin olive oil has been associated with a reduced incidence of risk factors for coronary heart disease also owing to the presence of antioxidant biophenols. This study compared the protective effects of tyrosol and hydroxytyrosol, two biophenols greatly different in antioxidant power, on J774 A.1-mediated oxidation of LDL. METHODS AND RESULTS: Cell-mediated oxidation of LDL was evaluated by TBARS formation, and relative electrophoretic mobility increase. Redox imbalance was studied by: (i) cytofluorimetric determination of intracellular ROS and GSH, and (ii) evaluation of GSH-related enzyme activities and gene expressions by colorimetric and RT-PCR analyses, respectively. The cellular uptake of the biophenols was evaluated by HPLC. Both biophenols inhibited cell-mediated oxidation of LDL but to a different extent (100% hydroxytyrosol vs 40% tyrosol), and counteracted the impairment of antioxidant cellular defence, i.e., GSH and related enzymes. Tyrosol was effective in inhibiting about 30% of ROS production only at later time-points (12h for superoxide, 24h for hydrogen peroxides). Interestingly, both biophenols were effective when added to the cells for 2h and removed before LDL treatment. This was probably related to cell-biophenol interactions: hydroxytyrosol was rapidly found inside the cells (1.12+/-0.05ng/mg cell protein) and disappeared within 18h, while tyrosol accumulated intracellularly with time (0.68+/-0.09 vs 1.72+/-0.13ng/mg cell protein at minute 5 and hour 18, respectively). CONCLUSIONS: In spite of its weak antioxidant activity, tyrosol was effective in preserving cellular antioxidant defences, probably by intracellular accumulation. These findings give further evidence in favour of olive oil consumption to counteract cardiovascular diseases.

Polyphenols, intracellular signalling and inflammation.

Excessive inflammation is considered as a critical factor in many human diseases, including cancer, obesity, type II diabetes, cardiovascular diseases, neurodegenerative diseases and aging. Compounds derived from botanic sources, such as phenolic compounds, have shown anti-inflammatory activity in vitro and in vivo. Recent data suggest that polyphenols can work as modifiers of signal transduction pathways to elicit their beneficial effects. These natural compounds express anti-inflammatory activity by modulation of pro-inflammatory gene expression such as cyclooxygenase, lipoxygenase, nitric oxide synthases and several pivotal cytokines, mainly by acting through nuclear factor-kappa B and mitogen-activated protein kinase signalling. This review will discuss recent data on the control of inflammatory signalling exerted by some dietary polyphenols contained in Mediterranean diet. A clear understanding of the molecular mechanisms of action of phenolic compounds is crucial in the valuation of these potent molecules as potential prophylactic and therapeutic agents.