K. Hirano

Reduced expression of adipose triglyceride lipase enhances tumor necrosis factor α-induced intercellular adhesion molecule-1 expression in human aortic endothelial cells via protein kinase c-dependent activation of nuclear factor-κB

Background: Adipose triglyceride lipase (ATGL) expression is decreased in the obese insulin-resistant state. Results: RNA interference-mediated down-regulation of ATGL enhanced monocyte adhesion via increased expression of tumor necrosis factor α-induced intercellular adhesion molecule-1. Conclusion: Reduced ATGL expression may influence the atherogenic process in the insulin-resistant state. Significance: This mechanism also leads to the acceleration of atherosclerosis in patients with insulin-resistance, even if not in a state of hyperglycemia. We examined the effects of adipose triglyceride lipase (ATGL) on the initiation of atherosclerosis. ATGL was recently identified as a rate-limiting triglyceride (TG) lipase. Mutations in the human ATGL gene are associated with neutral lipid storage disease with myopathy, a rare genetic disease characterized by excessive accumulation of TG in multiple tissues. The cardiac phenotype, known as triglyceride deposit cardiomyovasculopathy, shows massive TG accumulation in both coronary atherosclerotic lesions and the myocardium. Recent reports show that myocardial triglyceride content is significantly higher in patients with prediabetes or diabetes and that ATGL expression is decreased in the obese insulin-resistant state. Therefore, we investigated the effect of decreased ATGL activity on the development of atherosclerosis using human aortic endothelial cells. We found that ATGL knockdown enhanced monocyte adhesion via increased expression of TNFα-induced intercellular adhesion molecule-1 (ICAM-1). Next, we determined the pathways (MAPK, PKC, or NFκB) involved in ICAM-1 up-regulation induced by ATGL knockdown. Both phosphorylation of PKC and degradation of IκBα were increased in ATGL knockdown human aortic endothelial cells. In addition, intracellular diacylglycerol levels and free fatty acid uptake via CD36 were significantly increased in these cells. Inhibition of the PKC pathway using calphostin C and GF109203X suppressed TNFα-induced ICAM-1 expression. In conclusion, we showed that ATGL knockdown increased monocyte adhesion to the endothelium through enhanced TNFα-induced ICAM-1 expression via activation of NFκB and PKC. These results suggest that reduced ATGL expression may influence the atherogenic process in neutral lipid storage diseases and in the insulin-resistant state.

Downregulation of adipose triglyceride lipase in the heart aggravates diabetic cardiomyopathy in db/db mice

Adipose triglyceride lipase (ATGL) was recently identified as a rate-limiting triglyceride (TG) lipase and its activity is stimulated by comparative gene identification-58 (CGI-58). Mutations in the ATGL or CGI-58 genes are associated with neutral lipid storage diseases characterized by the accumulation of TG in multiple tissues. The cardiac phenotype, known as triglyceride deposit cardiomyovasculopathy, is characterized by TG accumulation in coronary atherosclerotic lesions and in the myocardium. Recent reports showed that myocardial TG accumulation is significantly higher in patients with diabetes and is associated with impaired left ventricular diastolic function. Therefore, we investigated the roles of ATGL and CGI-58 in the development of myocardial steatosis in the diabetic state. Histological examination with oil red O staining showed marked lipid deposition in the hearts of diabetic fatty db/db mice. Cardiac triglyceride and diglyceride contents were greater in db/db mice than in db/+ control mice. Next, we determined the expression of genes and proteins that affect lipid metabolism, and found that ATGL and CGI-58 expression levels were decreased in the hearts of db/db mice. We also found increased expression of genes regulating triglyceride synthesis (sterol regulatory element-binding protein 1c, monoacylglycerol acyltransferases, and diacylglycerol acyltransferases) in db/db mice. Regarding key modulators of apoptosis, PKC activity, and oxidative stress, we found that Bcl-2 levels were lower and that phosphorylated PKC and 8-hydroxy-2-deoxyguanosine levels were higher in db/db hearts. These results suggest that reduced ATGL and CGI-58 expression and increased TG synthesis may exacerbate myocardial steatosis and oxidative stress, thereby promoting cardiac apoptosis in diabetic mice.

Oxysterol changes along with cholesterol and vitamin D changes in adult phenylketonuric patients diagnosed by newborn mass-screening

BACKGROUNDnPhenylketonuria (PKU) possibly leads to hypocholesterolemia and lowered vitamin D (VD) status. Metabolism of oxysterols linking with those of cholesterol and VD has never been examined in PKU.nnnMETHODSnBlood oxysterols along with blood phenylalanine, lipids and VD were examined for 33 PKU adults aged 21-38 years and 20 age-matched healthy controls.nnnRESULTSnTotal- and low-density cholesterols, and 25-hydroxy VD(3) were decreased significantly in the PKU group (cholesterols, 10% decrease; 25-hydroxy VD(3) 35% decrease vs. the control group). 24S-hydroxycholesterol (24S-OHC) eliminating brain cholesterol, and 27-OHC and 7α-hydroxycholesterol (7α-OHC) representing peripheral and hepatic cholesterol elimination, respectively, were significantly decreased in PKU group: 24S-OHC, 25% decrease, p<.01; 27-OHC and 7α-OHC, 35-40% decrease, p<.001. 7β-Hydroxycholesterol (7β-OHC) reflecting oxidative stress was increased significantly in PKU group (p<.05). 7α-OHC and 27-OHC levels in PKU group always showed similar values, regardless of other parameters while the 24S-OHC and 7β-OHC levels decreased and increased, respectively, showing significant correlations with phenylalanine level (p<.005). 27-OHC level showed a significant positive correlation with the 25-hydroxy VD(3) level in this group (p<.001).nnnCONCLUSIONnBlood oxysterol changes predominate over blood cholesterol changes and influence on VD status in adult PKU patients.

Fluctuation of lipoprotein metabolism linked with bile acid-activated liver nuclear receptors in Alagille syndrome

Alagille syndrome (AGS) is a rare hereditary disorder exhibiting fluctuating cholestasis and dyslipidemia. Farnesoid X receptor (FXR) and liver X receptor (LXR) are hepatic nuclear receptors that regulate bile acid and lipoprotein metabolism. To investigate whether cholestasis is related to dyslipidemia and hepatic nuclear receptor expression in AGS patients, we determined the blood levels of total bile acid (TBA) and lipoprotein parameters, and examined hepatic nuclear receptor expression in three AGS children and their three incomplete AGS parents repeatedly over several years. In the AGS children, TBA level showed significant positive correlations with low-density lipoprotein-cholesterol, apolipoprotein E (apoE)-rich high-density lipoprotein-cholesterol (HDL-C), apoA-I, apoE, and cholesteryl ester transfer protein (CETP) concentrations, but negative correlation with apoE-poor HDL-C concentration. Western blot analysis of liver biopsy specimens revealed that FXR and LXR expression increased in parallel with TBA level. CETP- and ATP-binding cassette transporter A1 expression also increased with TBA level, while scavenger receptor class B type-I expression showed the opposite response. However, apoA-I expression was similar to the control level at any TBA level. In the incomplete AGS parents, TBA and lipoprotein parameters showed little fluctuation. In summary, cholestasis is closely related to dyslipidemia and hepatic nuclear receptor expression in AGS patients.

Depletion of high-density lipoprotein and appearance of triglyceride-rich low-density lipoprotein in a Japanese patient with FIC1 deficiency manifesting benign recurrent intrahepatic cholestasis

Objective: Lipoprotein metabolism in FIC1 deficiency due to ATP8B1 mutations has never been studied sufficiently. This study was performed to investigate the detailed lipoprotein metabolism in benign recurrent intrahepatic cholestasis (BRIC) caused by FIC1 deficiency. Patients and Methods: Lipoprotein profile and major lipoprotein regulators such as lecithin:cholesterol acyltransferase (LCAT), hepatic triglyceride lipase (HTGL), lipoprotein lipase, and cholesteryl ester transfer protein in a Japanese patient with BRIC were serially examined during a bout of cholestasis. Liver expression of farnesoid X receptor (FXR), which suppresses high-density lipoprotein (HDL) generation, was also examined. Results: Hypercholesterolemia and lipoprotein X accumulation were never observed throughout this study. When the cholestasis was severe, triglyceride-rich low-density lipoprotein (LDL) accounted for most of the plasma lipoproteins whereas HDL was hardly detectable. Concurrently, activities of all regulators were decreased, together with decreases of the serum parameter for liver protein synthesis. In particular, suppressions of LCAT and HTGL activities were severe and greatly contributed to the appearance of triglyceride-rich LDL. As the cholestasis improved, this LDL gradually transformed into normal LDL with the recoveries of LCAT and HTGL activities. The activities of all regulators for the last 1 to 2 months were normal but HDL remained depleted. His liver showed low FXR expression compared with control livers. Conclusions: The present study showed an appearance of triglyceride-rich LDL due to suppressions of LCAT and HTGL activities and a depletion of HDL that is not able to be explained by lipoprotein regulators or FXR in our patient.

Fibrinogen Storage Disease Caused by Aguadilla Mutation Presenting With Hypobeta-lipoproteinemia and Considerable Liver Disease

Children’s Center for Health and Development, Saiseikai Yokohama City Tobu Hospital, Yokohama, {Department of Pediatrics, Chiba Children’s Hospital, Chiba, {Department of Clinical Laboratory Medicine, Juntendo University School of Medicine, Tokyo, Journal of Pediatric Gastroenterology and Nutrition 49:133–136 # 2009 by European Society for Pediatric Gastroenterology, Hepatology, and Nutrition and North American Society for Pediatric Gastroenterology, Hepatology, and Nutrition

Metabolic improvements in intrahepatic porto-systemic venous shunt presenting various metabolic abnormalities by 4-phenylacetate

BACKGROUNDnIntrahepatic congenital portosystemic venous shunt (CPSVS) presents hyperammonemia, cholestasis, hypergalactosemia and imbalanced vasomediators. Especially, fluctuating plasma ammonia often causing neurological signs and symptoms is a serious problem in the daily life. 4-Phenylacetate (4-PA) has effects to eliminate blood ammonia, bile acids and bilirubin. 4-PA might be expected to improve the metabolic abnormalities in intrahepatic CPSVS.nnnMETHODSnThree intrahepatic CPSVS children often receiving 4-PA from early life were enrolled. We analyzed biological and clinical changes by intravenous administration of 4-PA.nnnRESULTSn4-PA improved hyperammonemia enough to subside the clinical presentations: headache, cognition dysfunction and attention deficit. Concurrently, this drug decreased serum total bilirubin and total bile acid levels. In their neonatal ages, 4-PA also decreased galactose and galactose-1-phosphate levels. In their preschool or school ages, 4-PA increased nitric oxide (NO) prompting vasodilation, but not changed amino acids controlling NO production and endothelin-1 prompting vasoconstriction. Plasma ammonia level returned to the pre-administration level within one day of the discontinuation, and serum total bilirubin and total bile acid levels were maintained to be reduced a few days after the discontinuation.nnnCONCLUSIONn4-PA improves galactosemia and imbalanced vasomediators, together with liver functions, in CPSVS, although such effects retract after the discontinuation.

CD36 deficiency predisposing young children to fasting hypoglycemia.

Fatty acid (FA) β-oxidation defects cause hypoglycemia. Our aim was to determine if CD36--a membrane transporter for long-chain FAs--deficiency predisposes children to hypoglycemia. After overnight fasting, we measured parameters for carbohydrate and FA metabolisms at 12-, 14-, and 16-hour fasting points in 51 preschool children with histories of episodic hypoglycemia and 49 age-matched healthy controls. Simultaneously, the expressions of CD36 on platelets and monocytes were examined to determine the phenotypes. Six of the 51 hypoglycemic children and none of the 49 control children were diagnosed as having type I CD36 deficiency. Four and 3 children were diagnosed as having type II CD36 deficiency, respectively. Hypoglycemia was often recurrent in the type I CD36 group. At any fasting point, the type I CD36 group showed significantly lower blood glucose and insulin concentrations than the other groups: glucose, P < .001 vs control group and P < .01 or P < .001 vs type II/wild-type CD36 hypoglycemic groups; insulin, P < .001 vs control group and P < .01 vs type II/wild-type CD36 hypoglycemic groups. Free FA concentration in the type I group was always 1.5- to 2.0-fold higher than that in the other groups, whereas the total ketone body concentration was consistently about two thirds of that in the other groups. Among the type II, wild-type, and control groups, there were no significant differences in the parameters except that the wild-type group showed significantly lower FFA concentration (P < .05). These results suggested that type I CD36 deficiency but not type II CD36 deficiency predisposes preschool children to hypoglycemia.

Changes of lipoproteins in phenylalanine hydroxylase-deficient children during the first year of life

BACKGROUNDnInfluence of hyperphenylalaninemia on lipoproteins in early life remains unclear.nnnMETHODSnWe enrolled 24 phenylalanine hydroxylase (PAH)-deficient children who were classified into a phenylketonuria (PKU) group (n=12) lacking PAH activity and a benign hyperphenylalaninemia (HPA) group (n=12) having partial PAH activity, and their 11 non-affected siblings. We measured serum total-cholesterol, low-density lipoprotein (LDL)-cholesterol, and high-density lipoprotein (HDL)-cholesterol levels together with apolipoproteins for the first year of life, and compared them with those of 30 age-matched healthy controls.nnnRESULTSnThe affected groups invariably had lower cholesterol levels than non-affected groups. At birth, HDL-cholesterol decrease was greatest and predominated over the LDL-cholesterol decrease: total cholesterol, 28/36% decrease to the control level in HPA/PKU; HDL-cholesterol, 33/51%; LDL-cholesterol, 20/28%. At 3months, the opposite changes were observed: total cholesterol, 16/28%; HDL-cholesterol, 13/23%; LDL-cholesterol, 16/33%. At 12months, LDL were still significantly lower in both groups (8/18%, p<.05 and .001), although HDL was significantly decreased only in the PKU group (15%, p<.05). Apolipoprotein A-I/A-II and B changed respectively in accordance with HDL-cholesterol and LDL-cholesterol changes. Despite similar phenylalanine levels, the PKU group invariably had lower cholesterol concentrations than the HPA group had.nnnCONCLUSIONnIrrespective of phenylalanine concentrations, lipoprotein synthesis in PAH-deficient children, particularly in PKU children, was suppressed in early life.

Sustained high plasma mannose less sensitive to fluctuating blood glucose in glycogen storage disease type Ia children

Plasma mannose is suggested to be largely generated from liver glycogen-oriented glucose-6-phosphate. This study examined plasma mannose in glycogen storage disease type Ia (GSD Ia) lacking conversion of glucose-6-phosphate to glucose in the liver. We initially examined fasting—and postprandial 2xa0h—plasma mannose and other blood carbohydrates and lipids for seven GSD Ia children receiving dietary interventions using cornstarch and six healthy age-matched children. Next, one-day successive intra-individual parameter changes were examined for six affected and two control children. Although there were no significant differences in fasting—and postprandial 2xa0h—glucose and insulin levels, the mannose level of the affected group was invariably much higher than that of the control group (pu2009<u20090.001): the fasting level of the affected group was about two-fold that of the control group; the postprandial-2xa0h level remained almost unchanged in the affected group, although it was one-half of the fasting level in the control group. Inter-individual analyses revealed that the GSD Ia group mannose level was significantly and positively correlated with lactate and triglycerides levels at both time points (pu2009<u20090.01). In each control, mannose levels fluctuated greatly, maintaining strong and significant negative correlations with glucose and insulin levels (pu2009<u20090.001). Correlations were lower or nonexistent in GSD Ia children. In individuals with high lactate and triglycerides levels, strikingly high mannose levels never changed against glucose and insulin fluctuations. Plasma mannose is less sensitive to blood glucose and insulin in GSD Ia children. Its basal level and the fluctuation pattern differ by their metabolic activity.