Elizabeth Hijona

Resveratrol inhibits nonalcoholic fatty liver disease in rats

BackgroundThe prevalence of nonalcoholic fatty liver disease (NAFLD) is high. NAFLD is linked to obesity, diabetes mellitus, and hypertriglyceridemia. Approximately 20% of patients with NAFLD will eventually develop cirrhosis. Our purpose was to investigate whether resveratrol decreased hepatic steatosis in an animal model of steatosis, and whether this therapeutic approach resulted in a decrease in tumor necrosis factor α (TNF-α) production, lipid peroxidation and oxidative stress.MethodsMale Wistar CRL: Wi (Han) (225 g) rats were randomized into three groups. A control group (n = 12) was given free access to regular dry rat chow for 4 weeks. The steatosis (n = 12) and resveratrol (n = 12) groups were given free access to feed (a high carbohydrate-fat free modified diet) and water 4 days per week, and fasted for the remaining 3 days for 4 weeks. Rats in the resveratrol group were given resveratrol 10 mg daily by the oral route. All rats were killed at 4 weeks and assessed for fatty infiltration and bacterial translocation. Levels of TNF-α in serum, hepatic malondialdehyde (MDA), oxidative stress (superoxide dismutase, glutathione peroxidase, catalase and nitric oxide synthase) and biochemical parameters were measured.ResultsFat deposition was decreased in the resveratrol group as compared to the steatosis group (Grade 1 vs Grade 3, P < 0.05). TNF-α and MDA levels were significantly increased in the steatosis group (TNF-α; 33.4 ± 5.2 vs 26.24 ± 3.47 pg/ml and MDA; 9.08 ± 0.8 vs 3.17 ± 1.45 μM respectively, P < 0.05). This was accompanied by increased superoxide dismutase, glutathione peroxidase and catalase and decreased nitric oxide synthase in the liver of resveratrol group significantly (P < 0.05 vs steatosis group). Bacterial translocation was not found in any of the groups. Glucose levels were decreased in the group of rats given resveratrol (P < 0.05).ConclusionResveratrol decreased NAFLD severity in rats. This effect was mediated, at least in part, by TNF-α inhibition and antioxidant activities.

Circulating MicroRNAs as Biomarkers of Colorectal Cancer: Results From a Genome-Wide Profiling and Validation Study

BACKGROUND & AIMS Circulating microRNAs (miRNAs/miRs) might be used as biomarkers for the diagnosis of cancer and other diseases. Noninvasive approaches are needed to complement and improve upon current strategies for colorectal cancer (CRC) screening. We investigated whether plasma levels of miRNA can differentiate patients with CRC from healthy individuals. We also investigated whether plasma samples from patients with premalignant neoplastic lesions, such as advanced adenomas (AAs), also had a different expression pattern of miRNAs. METHODS We analyzed 196 plasma samples from 123 patients newly diagnosed with sporadic colorectal neoplasia (63 with CRC and 60 with AAs) and 73 healthy individuals (controls) seen at 2 tertiary medical centers in Spain. An initial set of samples was analyzed using a genome-wide miRNA expression profiling assay (n = 61). Quantitative reverse-transcription PCR was used to validate the expression of selected miRNAs in an independent cohort (n = 135). RESULTS Patients with CRC or AAs had plasma miRNA expression profiles that differed significantly from those of controls. We selected a group of 13 miRNAs for validation in an independent cohort of patients; 6 (miR18a, miR19a, miR19b, miR15b, miR29a, and miR335) were confirmed to be significantly up-regulated in patients with CRC, differentiating patients with CRC from controls with area under the receiver operating characteristic curve values ranging from 0.80 (95% confidence interval [CI], 0.71-0.89) to 0.70 (95% CI, 0.59-0.80). Only miR18a was confirmed to be significantly up-regulated in patients with AAs, compared with controls; the area under the receiver operating characteristic curve value was 0.64 (95% CI, 0.52-0.75). CONCLUSIONS Patients with CRC have significantly different patterns of miRNA expression than healthy individuals. These patterns might be developed as biomarkers for CRC, although they have limited value in identifying patients with premalignant neoplastic lesions.

Inflammatory Mediators of Hepatic Steatosis

Nonalcoholic fatty liver disease (NAFLD) is rapidly becoming a world-wide public health problem. NAFLD represents a spectrum of disease ranging from “simple steatosis”, which is considered relatively benign, to nonalcoholic steatohepatitis and to NAFLD-associated cirrhosis and end-stage liver disease. The etiology of NAFLD and its progression is complex and remains incompletely understood. The progression of the disease involves many factors. Apart from the two hits, the accumulation of TG and the development of fibrosis and necroinflammatory processes, exit numerous molecules associated with these two hits. Among them we can highlight the pro-inflammatory molecules and adiponectins. This review focuses on the growing evidence from both experimental and human studies suggesting a central role of cytokines in the pathogenesis of NAFLD. We review the role of cytokines as key regulators of insulin sensitivity and hepatic lipid overloading, liver injury and inflammation, and fibrosis with an emphasis on potential therapeutic implications.

Mouse models of pancreatic cancer.

Pancreatic cancer is one of the most lethal of human malignancies ranking 4th among cancer-related death in the western world and in the United States, and potent therapeutic options are lacking. Although during the last few years there have been important advances in the understanding of the molecular events responsible for the development of pancreatic cancer, currently specific mechanisms of treatment resistance remain poorly understood and new effective systemic drugs need to be developed and probed. In vivo models to study pancreatic cancer and approach this issue remain limited and present different molecular features that must be considered in the studies depending on the purpose to fit special research themes. In the last few years, several genetically engineered mouse models of pancreatic exocrine neoplasia have been developed. These models mimic the disease as they reproduce genetic alterations implicated in the progression of pancreatic cancer. Genetic alterations such as activating mutations in KRas, or TGFb and/or inactivation of tumoral suppressors such as p53, INK4A/ARF BRCA2 and Smad4 are the most common drivers to pancreatic carcinogenesis and have been used to create transgenic mice. These mouse models have a spectrum of pathologic changes, from pancreatic intraepithelial neoplasia to lesions that progress histologically culminating in fully invasive and metastatic disease and represent the most useful preclinical model system. These models can characterize the cellular and molecular pathology of pancreatic neoplasia and cancer and constitute the best tool to investigate new therapeutic approaches, chemopreventive and/or anticancer treatments. Here, we review and update the current mouse models that reproduce different stages of human pancreatic ductal adenocarcinoma and will have clinical relevance in future pancreatic cancer developments.

Effects of resveratrol and other polyphenols in hepatic steatosis.

Non-alcoholic fatty liver disease covers a wide spectrum of liver pathologies which range from simple steatosis to non-alcoholic steatohepatitis. Polyphenols are members of a very large family of plant-derived compounds that can have beneficial effects on human health, and thus their study has become an increasingly important area of human nutrition research. The aim of the present review is to compile published data concerning the effects of both isolated polyphenols as well as polyphenol extracts, on hepatocyte and liver fat accumulation under different steatosis-inducing conditions. The results reported clearly show that this group of biomolecules is able to reduce fat accumulation, but further studies are needed to establish the optimal dose and treatment period length. With regard to the potential mechanisms of action, there is a good consensus. The anti-lipidogenic effect of polyphenols is mainly due to reduced fatty acid and triacylglycerol synthesis, increased in fatty acid oxidation, and reduced of oxidative stress and inflammation. As a general conclusion, it can be stated that polyphenols are biomolecules which produce hepatoprotective effects. To date, these beneficial effects have been demonstrated in cultured cells and animal models. Thus, studies performed in humans are needed before these molecules can be considered as truly useful tools in the prevention of liver steatosis.

Effects of resveratrol on obesity-related inflammation markers in adipose tissue of genetically obese rats

OBJECTIVE The aim of this study was to examine whether resveratrol might represent a promising therapeutic tool with which to combat adipose tissue chronic inflammation in a model of genetic obesity and to link its anti-inflammatory activity with its effect on body fat reduction. METHODS Twenty 6-wk-old male Zucker (fa/fa) rats were randomly distributed into two experimental groups. Resveratrol (RSV) was given orally (15 mg/kg body weight/d in RSV group) by means of an orogastric catheter for 6 wk. Enzyme activities were measured spectrophotometrically or fluorimetrically. Gene and protein expressions were analyzed by reverse transcriptase polymerase chain reaction and Western blot respectively. Cytokine concentrations and the activity of nuclear factor κ-light-chain-enhancer of activated β cells (NF-κB) were measured by using commercial kits. RESULTS RSV reduced the weight of internal adipose tissues. In epididymal depot glucose-6P-dehydrogenase, acetyl-CoA carboxylase activities, as well as lipoprotein lipase expression and activity were reduced by RSV. The expression of hormone-sensitive lipase was increased, and that of the cluster of differentiation 36 was reduced. Serum concentrations of tumor necrosis factor-α, monocyte chemoattractant protein 1, and C-reactive protein were lower in the RSV-treated group than in the control group. Protein expression of interleukin-6 and the activity of NF-κB, were decreased by RSV. CONCLUSION The present results provide evidence that fatty acid uptake and lipolysis are metabolic pathways involved in the response of adipose tissue to RSV. This polyphenol modulates plasma cytokine levels partially by reducing macrophage infiltration in adipose tissue and inhibiting NF-κB activity.

Alcohol consumption on pancreatic diseases.

Although the association between alcohol and pancreatic diseases has been recognized for a long time, the impact of alcohol consumption on pancreatitis and pancreatic cancer (PC) remains poorly defined. Nowadays there is not consensus about the epidemiology and the beverage type, dose and duration of alcohol consumption causing these diseases. The objective of this study was to review the epidemiology described in the literature for pancreatic diseases as a consequence of alcoholic behavior trying to understand the association between dose, type and frequency of alcohol consumption and risk of pancreatitis and PC. The majority of the studies conclude that high alcohol intake was associated with a higher risk of pancreatitis (around 2.5%-3% between heavy drinkers and 1.3% between non drinkers). About 70% of pancreatitis are due to chronic heavy alcohol consumption. Although this incidence rate differs between countries, it is clear that the risk of developing pancreatitis increases with increasing doses of alcohol and the average of alcohol consumption vary since 80 to 150 g/d for 10-15 years. With regard to PC, the role of alcohol consumption remains less clear, and low to moderate alcohol consumption do not appear to be associated with PC risk, and only chronic heavy drinking increase the risk compared with lightly drinkers. In a population of 10%-15% of heavy drinkers, 2%-5% of all PC cases could be attributed to alcohol consumption. However, as only a minority (less than 10% for pancreatitis and 5% for PC) of heavily drinkers develops these pancreatic diseases, there are other predisposing factors besides alcohol involved. Genetic variability and environmental exposures such as smoking and diet modify the risk and should be considered for further investigations.

Relevance of GSTM1, GSTT1, and GSTP1 gene polymorphisms to gastric cancer susceptibility and phenotype

Human glutathione S-transferases (GSTs) are phase II metabolizing enzymes that play a key role in protecting against cancer by detoxifying numerous potentially cytotoxic/genotoxic compounds. The genes encoding the human GST isoenzymes GSTM(mu)1, GSTT(theta)1 and GSTP(pi)1 harbour polymorphisms, which have been considered important modifiers of the individual risk for environmentally induced cancers such as gastric cancer (GC). However, results are inconsistent among studies from different geographic areas and ethnic groups. Our goal was to perform a nationwide, case-control study in Spain to evaluate the relevance of several functional GST gene polymorphisms and environmental factors to GC risk and phenotype. DNA from 557 GC patients and 557 sex- and age-matched healthy controls (HC) was typed for two deletions in the GSTM1 and GSTT1 genes and two SNPs in the GSTP1 gene (rs1695 and rs1138272) using polymerase chain reaction-restriction fragment length polymorphism methods. Logistic regression analysis identified Helicobacter pylori infection with CagA strains [odds ratio (OR): 2.36; 95% confidence interval (CI): 1.78-3.15], smoking habit (OR: 2.10; 95% CI: 1.48-2.97) and family history of GC (OR: 3.2; 95% CI: 2.02-5.16) as independent risk factors for GC. No differences in the frequencies of GSTM1 or GSTT1 null genotypes were observed between cases and controls (GSTM1: 50.8% vs. 48%; GSTT1: 21.5% vs. 21%). Moreover, simultaneous carriage of both, the GSTM1 and the GSTT1 null genotypes, was almost identical in both groups (10.7% in GC vs. 10.6% in HC). In addition, no significant differences in GSTP1 Ile105Val (rs1695) and GSTP1 Val114Ala (rs1138272) genotype distribution were observed between GC patients and controls. Subgroup analysis for age, gender, Helicobacter pylori status, smoking habits, family history of GC, anatomic location and histological subtype revealed no significant association between GST variants and GC risk. Our results show that the GST polymorphisms evaluated in this study are not relevant when determining the individual susceptibility to GC or phenotype in a South-European population.

Inhibition of metalloprotease hyperactivity in cystic cholangiocytes halts the development of polycystic liver diseases

Objective Polycystic liver diseases (PCLDs) are genetic disorders characterised by progressive bile duct dilatation and/or cyst development. Their pathogenesis is a consequence of hyperproliferation, hypersecretion and microRNA alterations in cholangiocytes. Here we evaluate the role of matrix metalloproteases (MMPs) in the hepatic cystogenesis of PCLDs. Design Metalloprotease activity was measured by microfluorimetric assays in normal and polycystic cholangiocyte cultures from humans and rats, and gene expression by real time quantitative PCR. The role of cytokines, oestrogens and growth factors present in the cystic fluid of PCLD patients was evaluated for MMP activity. The MMP inhibitor marimastat was examined for cystic expansion in vitro and in polycystic kidney (PCK) rats. Results Polycystic human and rat cholangiocytes displayed increased MMP activity, which was associated with increased mRNA levels of different MMPs. Interleukin (IL)-6 and IL-8, and 17β-oestradiol, all stimulated MMP activity in human cholangiocytes. The presence of antibodies against IL-6 and/or IL-8 receptor/s inhibited baseline MMP hyperactivity of polycystic human cholangiocytes but had no effect on normal human cholangiocytes. MMP-3 was overexpressed in cystic cholangiocytes from PCLD human and PCK rat livers by immunohistochemistry. Marimastat reduced MMP hyperactivity of polycystic human and rat cholangiocytes and blocked the cystic expansion of PCK cholangiocytes cultured in three-dimensions. Chronic treatment of 8-week-old PCK rats with marimastat inhibited hepatic cystogenesis and fibrosis. Conclusions PCLDs are associated with cholangiocyte MMP hyperactivity resulting from autocrine/paracrine stimulation by IL-6 and IL-8. Inhibition of this MMP hyperactivity with marimastat decreased hepatic cystogenesis in vitro and in an animal model of PCLD, offering a potential therapeutic tool.

MicroRNAs in biliary diseases

Cholangiopathies are a group of diseases primarily or secondarily affecting bile duct cells, and result in cholangiocyte proliferation, regression, and/or transformation. Their etiopathogenesis may be associated with a broad variety of causes of different nature, which includes genetic, neoplastic, immune-associated, infectious, vascular, and drug-induced alterations, or being idiopathic. miRNAs, small non-coding endogenous RNAs that post-transcriptionally regulate gene expression, have been associated with pathophysiological processes in different organs and cell types, and are postulated as potential targets for diagnosis and therapy. In the current manuscript, knowledge regarding the role of miRNAs in the development and/or progression of cholangiopathies has been reviewed and the most relevant findings in this promising field of hepatology have been highlighted.