- Email: [email protected]
1129 IRON OVERLOAD INCREASES SYMPATHETIC NERVOUS ACTIVITY: STUDY IN HEMOCHROMATOSIS PATIENTS AT DIAGNOSIS AND IRON DEPLETION
POSTERS 1129 IRON OVERLOAD INCREASES SYMPATHETIC NERVOUS ACTIVITY: STUDY IN HEMOCHROMATOSIS PATIENTS AT DIAGNOSIS AND IRON DEPLETION R. Mariani, A. Piperno, P. Trombini, S. Coletti, M. Pozzi, G. Seravalle, F. Quarti-Trevano, G. Grassi, G. Mancia. Department of Clinical Medicine and Prevention, San Gerardo Hospital, Milano-Bicocca University, Monza, Italy E-mail: [email protected] Background and Aims: Adrenergic vascular hyper-responsiveness is a hallmark of different cardiometabolic disease, including essential hypertension, diabetes, obesity, metabolic syndrome, heart failure and chronic kidney disease. Previous studies have shown that sympathetic activation and insulin resistance are closely related each other, but the cause-and-effect relationship remains undefined. Iron overload impairs glucose metabolism in hemochromatosis patients by either insulin resistance or decreased insulin secretion. There are no data on the effect of iron overload on the adrenergic overdrive. Methods: The study groups consisted of 15 iron-loaded hemochromatosis male patients without iron-related organ damage, at diagnosis, and 10 age-matched healthy male controls. We measured, during a 30-minute resting period, beat-to-beat blood pressure (Finapres), heart rate (ECG) and postganglionic muscle sympathetic nerve traffic (MSNA) via microneurography into the peroneal nerve. Seven hemochromatosis patients were evaluated also after iron depletion. All patients underwent Magnetic Resonance for the assessment of hepatic iron concentration (HIC). Metabolic syndrome (defined according to the ATPIII criteria), essential hypertension, diabetes, obesity, heart and kidney failure, and cirrhosis were considered metabolic confounders and they represented the exclusion criteria. Insulin resistance was estimated by HOMA index (normal value <2.77). Results: In hemochromatosis patients at diagnosis, mean serum ferritin was 825±407 mg/L, HIC 206±57 mmol/g and HOMA index 1.7±0.82. MSNA values were significantly higher than in controls (63.53±10.93 vs 35.36±10.85 bursts/100 heart beats, p = 0.0001). In iron depleted patients sympathetic activation significantly decreased (68.24±12.26 vs 40.39±11.04 bursts/100 heart beats, p = 0.0156) reaching the normal range. Conclusions: The present study indicates that iron overloaded male patients with hemochromatosis are characterized by a hyperadrenergic state. Iron overload contributes to adrenergic hyper-responsiveness and could be directly involved in the overactivity of the autonomic nervous system also in the absence of an insulin resistance condition. Iron-dependent generation of reactive oxygen species might be involved in the pathogenesis of the adrenergic overdrive and more generally in cardiovascular damage. 1130 HEPATIC REGULATION OF THE INSULIN-LIKE GROWTH FACTOR (IGF) SYSTEM BY ACUTE HYPOXIA IN CHILDREN 1 1 C.E. Martinelli Jr.1 , R.J. Custodio ´ , V.I.C. Custodio ´ , C.A. Scrideli1 , M.C. Cervi1 , P. Cupo1 , A.L.C. Martinelli2 . 1 Pediatrics, 2 Medicine, School of Medicine of Ribeir˜ ao Preto, University of S˜ ao Paulo, Ribeir˜ ao Preto, Brazil E-mail: [email protected]
Background: In animals the hypoxia associated to intra-uterine growth restriction is related to high concentrations of IGF-binding protein (IGFBP)-1 and unchanged IGF-I levels. Few data are available regarding IGFBP-3. These peptides are independently regulated and while IGF-I and IGFBP-1 are produced in the hepatocytes, IGFBP-3 is secreted by the endothelial cells in the hepatic sinusoids. Severe hypoxia increases the expression of IGF type 1 receptor (IGF1R) of the neuronal growth cones in the ovine fetal brain. No information S436
is available regarding the regulation of IGF system by acute hypoxia in humans. Aim: To evaluate the effect of acute hypoxia on the hepatic regulation of the IGF system in children. Methods: 27 previously health children (14 boys) aged 0.1 to 9.5 years were studied during acute hypoxia due to acute respiratory distress and after full recovering. In these two opportunities oxygen saturation was accessed using pulse-oximeter and blood samples were collected for serum IGF-I, IGFBP-1, IGFBP-3 and insulin determination (ELISA) and also for analyzing of IGF1R gene expression in peripheral lymphocytes. Levels of mRNA expression of the IGF1R gene were analyzed by quantitative real-time PCR. Data were pared-compared by Wilcoxon test. Results: Oxygen saturation was 88±3% in the first evaluation (HS) and 96±1% after recovering (non-HS) (P < 0.0001). IGF-I and IGFBP-3 levels were lower during HS compared to non-HS (medians: 12 vs. 56 ng/ml; P < 0.0001 and 1.0 vs. 2.1 mg/l; P = 0.03; respectively) whilst IGFBP-1 was higher during HS than in non-HS (113 vs. 60 ng/ml) (P = 0.004). No difference was found regarding insulin levels. The expression of IGF1R mRNA, expressed as 2−DDCT , were higher during HS than after it (1.3 vs. 0.9) (P = 0.03). Conclusion: The results show a direct effect of hypoxia on the liver production of IGFBP-1 independently of the classical inhibitory action of insulin, supporting the idea of a hypoxia-responsive element in the IGFBP-1 gene. The changes in IGF-I and IGFBP-3, both growth hormone (GH)-dependent-peptides, rise the hypothesis of decreased liver sensitivity to GH or even decreased pituitary GH secretion. These alterations are usually associated with decreased IGF action and the higher expression of IGF1R mRNA may reflect an up regulation of the transcriptional process. 1131 ANALYSIS OF GENE EXPRESSION ASSOCIATED TO HEPATOCARCINOMA DEVELOPMENT IN LIVER TISSUE OF THE FAH −/− MURINE MODEL OF HEREDITARY TYROSINEMIA TYPE 1 D. Orejuela, R.M. Tanguay. Molecular Biology, Medical Biochemistry and Pathology, Laval University, Quebec, QC, Canada E-mail: [email protected] Background and Aims: Hereditary Tyrosinemia type 1 (HT1) is a metabolic liver disease caused by lack of functional fumarylacetoacetate hydrolase (FAH), the last enzyme in the breakdown pathway of tyrosine. Severe hepatic damage and death during early childhood are observed unless 2-(2-nitro-4-trifluoromethylbenzoyl)-1,3-cyclohexadione (NTBC) is administered as therapeutic treatment. However, high incidence of hepatocarcinoma (HCC) is still observed in HT1 treated patients. The differential expression of genes between tumoral and non-tumoral hepatic sections has been analyzed in fah−/− mice to characterize the two sub-populations of cells. Methods: Liver tumors on fah−/− mice were obtained by repeated interruption of NTBC treatment. Total RNA was extracted from distinct tumoral and non-tumoral tissues for analysis using Agilent 44K Mouse Hole Genome Oligonucleotide Microarray (containing 41,534 genes). The GeneSpring software was used to draw up a list of up- and down-regulated genes displaying a cutoff expression value ≥2.00. The most relevant regulated genes in the HT1-related survival signaling were chosen by analysis of whole data with the Ingenuity software and their expression levels were confirmed by quantitative real-time PCR (qPCR). Results: The tumoral sections showed the overexpression of many stress and mitochondrial-based cell death resistance genes, compared to non-diseased (fah+/+) and treated (fah−/− under NTBC) controls. Importantly, genes associated to activation of the AKT pathway, as those coding for numerous MAPK kinases, for the antiapoptotic heat shock proteins HSP25 and HSP70 and for regulators of the PP2A phosphatase, were highly up-regulated in liver tumors.
Journal of Hepatology 2010 vol. 52 | S319–S457
Background: In animals the hypoxia associated to intra-uterine growth restriction is related to high concentrations of IGF-binding protein (IGFBP)-1 and unchanged IGF-I levels. Few data are available regarding IGFBP-3. These peptides are independently regulated and while IGF-I and IGFBP-1 are produced in the hepatocytes, IGFBP-3 is secreted by the endothelial cells in the hepatic sinusoids. Severe hypoxia increases the expression of IGF type 1 receptor (IGF1R) of the neuronal growth cones in the ovine fetal brain. No information S436
is available regarding the regulation of IGF system by acute hypoxia in humans. Aim: To evaluate the effect of acute hypoxia on the hepatic regulation of the IGF system in children. Methods: 27 previously health children (14 boys) aged 0.1 to 9.5 years were studied during acute hypoxia due to acute respiratory distress and after full recovering. In these two opportunities oxygen saturation was accessed using pulse-oximeter and blood samples were collected for serum IGF-I, IGFBP-1, IGFBP-3 and insulin determination (ELISA) and also for analyzing of IGF1R gene expression in peripheral lymphocytes. Levels of mRNA expression of the IGF1R gene were analyzed by quantitative real-time PCR. Data were pared-compared by Wilcoxon test. Results: Oxygen saturation was 88±3% in the first evaluation (HS) and 96±1% after recovering (non-HS) (P < 0.0001). IGF-I and IGFBP-3 levels were lower during HS compared to non-HS (medians: 12 vs. 56 ng/ml; P < 0.0001 and 1.0 vs. 2.1 mg/l; P = 0.03; respectively) whilst IGFBP-1 was higher during HS than in non-HS (113 vs. 60 ng/ml) (P = 0.004). No difference was found regarding insulin levels. The expression of IGF1R mRNA, expressed as 2−DDCT , were higher during HS than after it (1.3 vs. 0.9) (P = 0.03). Conclusion: The results show a direct effect of hypoxia on the liver production of IGFBP-1 independently of the classical inhibitory action of insulin, supporting the idea of a hypoxia-responsive element in the IGFBP-1 gene. The changes in IGF-I and IGFBP-3, both growth hormone (GH)-dependent-peptides, rise the hypothesis of decreased liver sensitivity to GH or even decreased pituitary GH secretion. These alterations are usually associated with decreased IGF action and the higher expression of IGF1R mRNA may reflect an up regulation of the transcriptional process. 1131 ANALYSIS OF GENE EXPRESSION ASSOCIATED TO HEPATOCARCINOMA DEVELOPMENT IN LIVER TISSUE OF THE FAH −/− MURINE MODEL OF HEREDITARY TYROSINEMIA TYPE 1 D. Orejuela, R.M. Tanguay. Molecular Biology, Medical Biochemistry and Pathology, Laval University, Quebec, QC, Canada E-mail: [email protected] Background and Aims: Hereditary Tyrosinemia type 1 (HT1) is a metabolic liver disease caused by lack of functional fumarylacetoacetate hydrolase (FAH), the last enzyme in the breakdown pathway of tyrosine. Severe hepatic damage and death during early childhood are observed unless 2-(2-nitro-4-trifluoromethylbenzoyl)-1,3-cyclohexadione (NTBC) is administered as therapeutic treatment. However, high incidence of hepatocarcinoma (HCC) is still observed in HT1 treated patients. The differential expression of genes between tumoral and non-tumoral hepatic sections has been analyzed in fah−/− mice to characterize the two sub-populations of cells. Methods: Liver tumors on fah−/− mice were obtained by repeated interruption of NTBC treatment. Total RNA was extracted from distinct tumoral and non-tumoral tissues for analysis using Agilent 44K Mouse Hole Genome Oligonucleotide Microarray (containing 41,534 genes). The GeneSpring software was used to draw up a list of up- and down-regulated genes displaying a cutoff expression value ≥2.00. The most relevant regulated genes in the HT1-related survival signaling were chosen by analysis of whole data with the Ingenuity software and their expression levels were confirmed by quantitative real-time PCR (qPCR). Results: The tumoral sections showed the overexpression of many stress and mitochondrial-based cell death resistance genes, compared to non-diseased (fah+/+) and treated (fah−/− under NTBC) controls. Importantly, genes associated to activation of the AKT pathway, as those coding for numerous MAPK kinases, for the antiapoptotic heat shock proteins HSP25 and HSP70 and for regulators of the PP2A phosphatase, were highly up-regulated in liver tumors.
Journal of Hepatology 2010 vol. 52 | S319–S457