Increased FNDC5/Irisin expression in human hepatocellular carcinoma.

The fibronectin type III domain containing 5 (FNDC5)/Irisin, a novel energy-regulating hormone, is associated with lipid and carbohydrate metabolism. It is produced in low amounts by normal hepatic tissue, while in human hepatocellular carcinoma (HCC), in which aberrant de novo lipogenesis (DNL) occurs, the hepatic expression of FNDC5/Irisin is still unknown. The gene expression of FNDC5/Irisin, associated to key regulators of DNL, inflammation and cancer progression was evaluated in liver tissue of 18 patients with HCC undergoing liver transplantation and of 18 deceased donors. Hepatic mRNA expression of FNDC5/Irisin and stearoyl-CoA desaturase (SCD-1), main enzymatic regulator of DNL, were significantly higher in HCC patients than in donors (p<0.0001 and p=0.015, respectively). The hepatic mRNA expression of the neurogenic locus notch homolog protein 1 (NOTCH1) tended to be higher in HCC patients than in donors (p=0.06). Only in HCC patients, hepatic FNDC5/Irisin strongly correlated with the transcription factor sterol regulatory element-binding factor 1, SCD-1, NOTCH1, tumor necrosis factor-α and Interleukin-6 mRNA expression. Further, in HCC patients, FNDC5/Irisin mRNA tended to correlate to plasma lipid profile namely triglycerides, palmitic/linoleic acid and polyunsaturated fatty acid/saturated fatty acid ratios. In conclusion, HCC-liver tissue over-expressed FNDC5/Irisin in association with gene expression of mediators involved in lipogenesis, inflammation and cancer, suggesting a possible protective role of the hormone from the liver damage.

Circulating levels of soluble receptor for advanced glycation end products and ligands of the receptor for advanced glycation end products in patients with acute liver failure.

Animal studies suggest that receptor for advanced glycation end products (RAGE)-dependent mechanisms contribute to acetaminophen-induced liver damage. We examined whether circulating levels of soluble receptor for advanced glycation end products (sRAGE) or RAGE ligands, including extracellular newly identified receptor for advanced glycation end products binding protein (EN-RAGE), high-mobility group box 1 (HMGB1), and Nε-(Carboxymethyl)lysine adducts (CML), could aid in prognostication after an acetaminophen overdose. Sixty well-characterized acetaminophen-related acute liver failure (ALF) patients (30 spontaneous survivors and 30 patients who underwent transplantation and/or died) who were enrolled in the National Institutes of Health-sponsored Acute Liver Failure Study Group, were matched by age, met standard criteria for encephalopathy, and had an international normalized ratio > 1.5 were retrospectively studied. HMGB1, EN-RAGE, CML, and sRAGE were detected by enzyme-linked immunosorbent assay methods in sera from ALF patients and 30 healthy controls. Levels of sRAGE, EN-RAGE, and HMGB1 (but not CML) were significantly greater (P < 0.001) in ALF patients versus normal controls. The levels of sRAGE, HMGB1, and EN-RAGE were significantly higher (P = 0.03, P < 0.01, and P = 0.03) in patients with a systemic inflammatory response syndrome (SIRS) score > 2 versus patients with a SIRS score ≤ 2. Nevertheless, only sRAGE levels were significantly higher in patients who underwent transplantation and/or died versus spontaneous survivors (P < 0.001), and they were positively associated with conventional markers of liver disease severity. Multivariate logistic regression identified an encephalopathy grade > 2 as an independent predictor of an adverse outcome on admission (odds ratio, 13; 95% confidence interval, 2.3-73; P < 0.001). The RAGE-ligand axis may interfere with liver regeneration and should be a promising objective for further research.

Involvement of the receptor for advanced glycation end products in liver transplantation.

BACKGROUND AND AIM: Receptor for advanced glycation end products (RAGE) blockade by a soluble form of RAGE (sRAGE) appears to be protective against hepatocellular death and necrosis after I/R injury. Little is known about the role of the hepatic RAGE, its ligands, and the plasma levels of sRAGE in liver transplantation (LT). MATERIAL AND METHODS: This was a prospective study on patients (n = 28) undergoing deceased donor LT. RAGE ligands [the N(epsilon)-carboxy-methyl-lysine (CML) adduct and the high-mobility group box 1 (HMGB1) protein] and sRAGE levels were measured in donors at the time of organ procurement, while in recipients they were tested before surgery (baseline), after graft reperfusion, and on day 1 and 7 posttransplantation. Donors and recipients liver biopsies were collected to assess the transcriptional expression of the full-length RAGE and of its truncated isoform, the endogenous secreted RAGE (esRAGE). RESULTS: At baseline, CML levels were higher in LT recipients than in donors (p = 0.02), decreased immediately after graft reperfusion (p < 0.0001) and returned to baseline values on day 7. Baseline HMGB1 levels (3.8 ± 2.3 ng/mL) increased after graft reperfusion (39.9±18 ng/mL, p < 0.0001), and returned to baseline values within day 1, while circulating sRAGE decreased significantly on day 7 (p < 0.0001). The graft esRAGE mRNA expression was inversely associated with bilirubin on day 7 (ß = -0.62, p = 0.005). CONCLUSIONS: Early on after LT, there is accumulation of CML and a rapid increase of HMGB1 concurrent with a remarkable decline in circulating sRAGE. The RAGE-ligand axis may also be involved in early graft dysfunction.

Effects of single and fractionated low-dose irradiation on vascular endothelial cells.

OBJECTIVE: An increasing number of epidemiological studies suggest that chronic low-dose irradiation increases the risk of atherosclerosis. We evaluated and compared the in vitro biological effects of both single and fractionated low-doses of X-ray irradiation on endothelial cells. METHODS: Human umbilical vein endothelial cells (HUVECs) were irradiated with X-rays, with single doses of 0.125, 0.25 and 0.5 Gy or fractionated doses of 2 × 0.125 Gy and 2 × 0.25 Gy, with 24 h interfraction interval. Survival, apoptosis, reactive oxygen species (ROS) production, nuclear factor-κB (NF-κB) activation, intercellular adhesion molecule-1 (ICAM-1) expression, HUVEC adhesiveness and DNA damage were investigated. RESULTS: We did not observe any effect on viability and apoptosis. Both single and fractionated doses induced ROS generation, NF-κB activation, ICAM-1 protein expression and HUVEC adhesiveness, but only fractionated doses increase significantly ICAM-1 mRNA. The effects measured after fractionated dose result always higher than those induced by the single dose. Moreover, we observed that DNA double strand break (DSB), visualized with γ-H2AX foci, is dose-dependent and that the kinetics of γ-H2AX foci is not affected by fractionated doses. CONCLUSIONS: We showed that single and fractionated low-dose irradiations with low energy X-rays do not affect cell viability and DNA repair. Interestingly, the greater increase of ICAM-1 surface exposure and endothelial adhesiveness observed after fractionated irradiation, suggests that fractionated low-doses may accelerate chronic vascular inflammation, from which the atherosclerotic process can arise.

Procoagulant activity of circulating microparticles is associated with the presence of moderate calcified plaque burden detected by multislice computed tomography.

BACKGROUND: Circulating microparticles (MPs) have been reported to be associated with coronary artery disease (CAD). In this study, we explored the relationship between MPs procoagulant activity and characteristics of atherosclerotic plaque detected by 64-slice computed tomography angiography (CTA). METHODS: In 127 consecutive patients with CAD but without acute coronary syndrome and who underwent 64-slice CTA, MPs procoagulant activity in plasma (by a thrombin generation test), soluble form of lectin-like oxidized low-density lipoprotein receptor-1 (sLOX-1) and N(epsilon)-(carboxymethyl) lysine (CML) circulating levels (by ELISA) were measured. A quantitative volumetric analysis of the lumen and plaque burden of the vessel wall (soft and calcific components), for the three major coronary vessels, was performed. The patients were classified in three groups according to the presence of calcium volume: non-calcified plaque (NCP) group (calcium volume (%) = 0), moderate calcified plaque (MCP) group (0 < calcium volume (%) < 1), and calcified plaque (CP) group (calcium volume (%) ≥ 1). RESULTS: MPs procoagulant activity and CML levels were higher in MCP group than in CP or NCP group (P = 0.009 and P = 0.027, respectively). MPs procoagulant activity was positively associated with CML (r = 0.317, P < 0.0001) and sLOX-1 levels (r = 0.216, P = 0.0025). CONCLUSIONS: MPs procoagulant activity was higher in the MCP patient group and correlated positively with sLOX-1 and CML levels, suggesting that it may characterize a state of blood vulnerability that may locally precipitate plaque instability and increase the risk of subsequent major cardiovascular events.

A novel 2,3-diphenyl-4H-pyrido[1,2-a]pyrimidin-4-one derivative inhibits endothelial cell dysfunction and smooth muscle cell proliferation/activation.

Hyper-proliferation and migration of vascular smooth muscle cells and endothelial cell dysfunction are central events in the development of neo-intimal lesions. Pursuing our interest in the synthesis of bioisosters of flavonoids, we studied in depth a novel synthetic 2,3-diphenyl-4H-pyrido[1,2-a]pyrimidin-4-one derivative, examining its effects in vitro on induced-cell proliferation and activation in human aortic smooth muscle cells (HAoSMCs) and in human umbilical vein endothelial cells (HUVECs). Compared with two well known flavonoids, apigenin and quercetin, the novel compound, 2-(3,4-dimethoxyphenyl)-3-phenyl-4H-pyrido[1,2-a]pyrimidin-4-one, 3, was not toxic for HUVECs, even at high concentrations and for long incubation times, while the two flavonoids were not tolerated, even at concentrations as low as 10 µmol/L. Compound 3 inhibited selectively, and in a concentration-dependent manner, the proliferation of HAoSMCs but not that of HUVECs. In HUVECs, it inhibited the cytokine-induced vascular cell adhesion molecule-1 expression, but not the cyclooxygenase-2 (COX-2) expression. Instead, in HAoSMC, it inhibited the induction of COX-2 expression and the relative release of prostaglandin E2. In addition, it inhibited the transcription of the matrix metalloproteinase-9 and its activity. Thanks to its multiple and tissue-specific function, 2-(3,4-dimethoxyphenyl)-3-phenyl-4H-pyrido[1,2-a]pyrimidin-4-one might replace or assist the action of current drugs eluted by coronary stents, in order to promote a functional repair of damaged wall.

Inverse association between circulating levels of soluble receptor for advanced glycation end-products and coronary plaque burden.

AIM: Low levels of soluble receptor for advanced glycation end-products (sRAGE) have been reported to be associated with coronary artery disease (CAD) and peripheral atherosclerosis. This study explored the relationship between circulating levels of sRAGE and the characteristics of coronary vessels detected by 64-slice computed tomography angiography (CTA). METHODS: In this cross-sectional study we included 127 consecutive patients with CAD but without acute coronary syndrome. Quantitative volumetric analysis of the lumen and plaque burden of the vessel wall (soft and calcific components) was performed for the three major coronary vessels. Each component was expressed as a percentage of vessel volume and utilized in per-patient analysis. The patients were classified into two groups according to the presence of calcium volume: non-calcified plaque (NCP) group (calcium volume %=0) and calcified plaque (CP) group (calcium volume % >0). RESULTS: In the NCP group, but not in the CP group, simple regression analysis revealed a negative association of total plaque burden % with sRAGE (ß=-0.378, p=0.0019) and HDL cholesterol (ß=-0.368, p=0.003) and a positive association with creatinine (ß=0.258, p=0.041) and male gender (ß=0.317, p=0.01). After adjusting for confounding factors, the total plaque burden % remained significantly associated only with sRAGE (ß=-0.358, p=0.011). CONCLUSIONS: Circulating sRAGE levels are associated in an inverse manner with non-calcified plaque burden, suggesting that it may be related with early atherosclerosis and plaque progression.

Elevated soluble receptor for advanced glycation end product levels in patients with acute coronary syndrome and positive cardiac troponin I.

OBJECTIVES: High levels of soluble receptor for advanced glycation end products (sRAGE) have been shown to have an atheroprotective role; however, no data are available on this molecule in acute coronary syndromes (ACS). We evaluated sRAGE levels in patients with non-ST segment elevation ACS (NSTE-ACS) or with chronic stable angina. METHODS: We studied 265 patients, 190 of whom had NSTE-ACS and 75 had chronic stable angina. RESULTS: Plasma sRAGE values were comparable in the two groups (P=0.19). However, in the patients with NSTE-ACS, sRAGE levels were significantly higher in patients with cardiac troponin-I (cTnI) of more than or equal to 0.04 µg/l compared with those with cTnI of less than 0.04 µg/l [758 (493-1536 ) pg/ml vs. 454 (167-899) pg/ml; P=0.0037]. A significant correlation (r=0.323, P=0.0045) was found between sRAGE and cTnI levels in patients with NSTE-ACS. CONCLUSION: Plasma sRAGE levels are elevated in patients with NSTE-ACS with positive cTnI, suggesting that they could be related to myocardial cell damage.

Protective role of adiponectin on endothelial dysfunction induced by AGEs: a clinical and experimental approach.

OBJECTIVE: Obesity is characterized by low levels of adiponectin, an adipocytes derived hormone, and by an inflammatory component. Endothelial dysfunction is often found in overweight/obesity, diabetes, and atherosclerosis. Advanced glycation end products (AGEs) induce endothelial dysfunction and are linked to diabetes and increased atherogenicity and inflammation. The aim of the study was to investigate the possible link between adiponectin and N(epsilon)-(carboxymethyl) lysine (CML), the predominant adduct of circulating AGEs in overweight patients, and, in an in vitro model, to test the hypothesis that adiponectin acts as modulator of endothelial dysfunction, induced by AGEs. RESULTS: In 108 overweight patients, plasma levels of CML correlated inversely with adiponectin levels. Pre-incubation of human vein endothelial cells (HUVECs) with physiological concentrations of adiponectin, followed by stimulation with AGEs, reduced vascular adhesion molecule-1 (VCAM-1) and E-selectin expression, as assessed by surface enzyme immunoassay. CONCLUSIONS: Taken together, these findings demonstrate an inverse correlation between CML and adiponectin levels in overweight patients and a protective role of adiponectin on endothelial dysfunction induced by AGEs, suggesting its key role in the treatment of the vascular complications of obesity/metabolic syndrome.

What is the role of the receptor for advanced glycation end products-ligand axis in liver injury?

Multiligand receptor for advanced glycation end products (RAGE) is expressed in a wide variety of tissues, including the liver. Interactions with its ligands lead to cellular activation and thus prolonged inflammation and apoptosis. RAGE also exists in a soluble, truncated isoform called soluble RAGE, which has the same ligand-binding specificity as membrane-RAGE; acting as decoy, it can contribute to the removal/neutralization of circulating ligands and the resultant reduction of signaling pathway activation. Experimental and clinical studies have highlighted the idea that the RAGE-ligand axis is involved in the development of liver fibrosis, inflammation, and regeneration after a massive injury and in the setting of liver transplantation. The involvement of the RAGE-ligand axis in vascular disease, diabetes, cancer, and neurodegeneration is well established, but it still needs to be clarified in the setting of liver diseases. We present a review of the recent literature on this receptor in surgical and clinical settings involving the liver, and we highlight the open issues and possible directions of future research.

Circulating soluble receptor for advanced glycation end-product levels are decreased in patients with calcific aortic valve stenosis.

OBJECTIVE: It has been suggested that atherosclerotic mechanisms are involved in the pathogenesis of aortic valve stenosis (AVS). We hypothesised that low levels of the soluble receptor for advanced glycation end-products (sRAGE) might be associated with AVS due to its clinical and pathological associations with atherosclerosis. METHODS: We enrolled 75 consecutive patients with severe AVS scheduled for surgical aortic valve replacement and 39 controls without AVS matched for age and gender. Besides the traditional risk factors, we evaluated plasma levels of sRAGE, C-reactive protein (CRP) and IL-6. All patients underwent transthoracic echocardiography, carotid arteries ultrasound scan and coronary angiography. The aortic and coronary calcium by multislice computed tomography was assessed in AVS patients. RESULTS: The values of sRAGE were significantly lower (p<0.01) in AVS patients than in controls, while the CRP levels were significantly higher (p<0.05) in AVS patients than in controls. In AVS patients the sRAGE levels correlated inversely with age, cholesterol levels and coronary calcification. In all study subjects, we found an inverse correlation between circulating sRAGE and the number of echographically assessed sites of calcification (ANOVA, p<0.0001). In multivariable logistic regression analysis after adjustment for potential confounders, the sRAGE levels were significantly and independently associated with the risk of AVS (OR=0.997, 95% CI=0.994-1.000, p=0.048). CONCLUSION: Since sRAGE could exert antiatherogenic effects by preventing inflammatory responses mediated by cell surface RAGE activation, low levels in AVS patients indicate that ligand-RAGE axis could contribute to pathogenesis of AVS.

The lectin-like oxidized low-density lipoprotein receptor-1 and its soluble form: cardiovascular implications.

The lectin-like oxidized low density lipoprotein receptor-1 (LOX-1) is a multiligand receptor, whose repertoire of ligands includes oxidized low-density lipoprotein, advanced glycation endproducts, platelets, neutrophils, apoptotic/aged cells and bacteria. Sustained expression of LOX-1 by critical target cells, including endothelial cells, smooth muscle cells and macrophages in proximity to these ligands, sets the stage for chronic cellular activation and tissue damage suggesting the interaction of cellular LOX-1 with its ligands to contribute to the formation and development of atherosclerotic plaques. Studies with transgenic and knockout mouse models have elucidated in part the role of LOX-1 in the pathogenesis of atherosclerosis and cardiac remodeling. Recently, a circulating soluble form of LOX-1 (sLOX-1), corresponding solely to its extracellular domain, has been identified in human serum. Circulating levels of sLOX-1 are increased in inflammatory and atherosclerotic conditions and are associated with acute coronary syndrome, with the severity of coronary artery disease, and with serum biomarkers for oxidative stress and inflammation, suggesting that they could be a useful marker for vascular injury. However, many interesting questions have not yet been answered and in this review, we provide an updated overview of the literature on this receptor and on likely future directions.

Lack of effect of alpha-tocopherol on in vitro angiogenesis.

Oxidative stress and angiogenesis are important elements in the pathogenesis of atherosclerosis and cancer. Because of its antioxidant properties, alpha-tocopherol has long proposed as prevention of diseases associated with oxidative stress. We explore whether alpha-tocopherol modulates some cell responses induced by angiogenic and proliferative stimuli. For this purpose, we evaluate the effect in human vein endothelial cells (HUVECs), of alpha-tocopherol treatment (5-40 micromol/L) for 72 h on the production of reactive oxygen species (ROS), induction of matrix metalloproteinases (MMPs), expression of vascular endothelial-cadherin (VE-cadherin) and alpha(2)-integrin, cell migration, cell proliferation, and tube formation. alpha-Tocopherol significantly inhibits intracellular ROS production induced by TNF-alpha (P < 0.01) or PMA (P < 0.001). However, alpha-tocopherol does not interfere with mRNA expression of VE-cadherin, alpha(2)-integrin, MMP-1, MMP-2, and MMP-9. Similarly, alpha-tocopherol does not modulate cell migration and capillary-like tube formation although at the concentration of 20 and 40 micromol/L it potentiated PMA-induced DNA synthesis (P < 0.05). Our results suggest that although alpha-tocopherol supplementation reduces endothelial cell oxidative stress, it does not alter the cell response to angiogenic stimuli.