Effect of cirrhosis on hepatic glycogen metabolism in humans

Progressive decrease in tissue glycogen content in rats with long-term cholestasis

Liver and skeletal muscle glycogen metabolism were investigated in rats 1 and 4 weeks after bile duct ligation (BDL) and in pair–fed, sham– operated control rats. Livers were subjected to morphometric analysis to express glycogen content and enzyme activities per mL hepatocytes. One week after BDL, the hepatic glycogen content was 28.8 ± 13.8 versus 38.6 ± 16.4 mg/mL hepatocyte in BDL and control rats, respectively. Total activity of glycogen synthase (50.2 ± 7.0 vs. 63.5 ± 9.4 mU/mL hepatocytes) and glycogen phosphorylase (59.4 ± 12.9 vs. 90.8 ± 18.9 U/mL) were significantly reduced in BDL whereas the active fraction of glycogen synthase (27 ± 6 vs. 38 ± 5%) but not of glycogen phosphorylase was reduced. The skeletal muscle glycogen content was not different between BDL and control rats. Four weeks after BDL, hepatic glycogen content was further reduced (20.5 ± 14.2 vs. 52.9 ± 6.4 mg/mL). Total activity of glycogen synthase (38.8 ± 12.1 vs. 60.1 ± 4.6 mU/mL hepatocytes) and glycogen phosphorylase (127 ± 19 vs. 178 ± 33 U/mL hepatocytes) were both reduced in BDL rats as were their corresponding active fractions (30 ± 18 vs. 66 ± 8% and 58 ± 10 vs. 76 ± 10). At this time point, the glycogen content in soleus muscle was decreased by 64% in BDL. The glucagon plasma concentration was increased in BDL rats at both time points. There were positive correlations between the volume fraction and both hepatic glycogen content and total activity of hepatic glycogen synthase. Plasma glucagon and the active fraction of hepatic glycogen synthase were negatively correlated. The current studies show a progressive decrease in the hepatic and skeletal muscle glycogen content in BDL rats. The observed decrease in the activities of glycogen synthase and phosphorylase suggest that reduced glycogen synthesis is the major mechanism leading to the reduction in the hepatic glycogen content in BDL rats.

To determine the effects of fetal beta-2 agonist exposure on fetal hepatic glycogen metabolism, we infused ritodrine at a rate of 1.3 +/- 0.4 microgram/kg/min (mean +/- SD) for 24 h into six chronically catheterized twin fetal lambs starting between 128 and 134 days gestation. The control twins received 0.9% saline at 1.2 +/- 0.12 ml/kg/h. In addition, 15 uncatheterized fetuses were killed between 115 and 148 days gestation as unoperated controls. Ritodrine infusion produced a 1.7-fold elevation in fetal serum glucose level, from 23 +/- 5 to 42 +/- 15 mg/dl, and a 2-fold elevation in serum insulin level, from 16 +/- 5 to 34 +/- 8 mg/ml, p less than 0.01. Hepatic glycogen content increased 7-fold in the uncatheterized controls between 115 and 148 days gestation (r = 0.9, p less than 0.001). Ritodrine infusion reduced hepatic glycogen content by 50% from 179 +/- 19 micrograms/mg in twin controls to 90 +/- 25 micrograms/mg in the ritodrine-infused twins, p less than 0.001. Hepatic glycogen phosphorylase kinase activity was elevated 1.3-fold from 0.149 +/- 0.100 mU/mg protein in control twins to 0.186 +/- 0.007 mU/mg protein in the ritodrine infused twins, p less than 0.001. Glycogen phosphorylase a activity was also increased 1.4-fold from 8.60 +/- 0.76 nM NADPH/min/mg protein in control twins to 11.85 +/- 0.68 nM NADPH/min/mg protein in the ritodrine infused twins, p less than 0.001.(ABSTRACT TRUNCATED AT 250 WORDS)

Patients with alcoholic liver cirrhosis have reduced hepatic glycogen stores but the mechanisms leading to this finding are not clear. We therefore determined the hepatic glycogen content in patients with alcoholic (n = 9) or biliary cirrhosis (n = 8), and in control patients undergoing liver surgery (n = 14). All patients were in the postabsorptive state. In addition, we performed a morphometric analysis of the livers, and measured activities and mRNA expression of several enzymes involved in glycogen metabolism. Cirrhotic and control patients were similar regarding age and body weight. Cirrhotic patients had a reduced glycogen content per gram liver wet weight (17 +/- 11 versus 45 +/- 17 mg/g, P < 0.05), per milliliter hepatocytes (28 +/- 16 versus 52 +/- 21 mg/ml, P < 0.05) and per liver (28 +/- 17 versus 64 +/- 22 g, P < 0.05), the reduction being observed in both patients with alcoholic or biliary cirrhosis. Liver histology confirmed these findings and revealed that the decrease in liver glycogen in cirrhotic patients was not homogeneous across cirrhotic lobules. Activities of glycogen synthase and phosphorylase (total activity and active form) were not different between cirrhotic and control patients, whereas hepatic mRNA expression was decreased in cirrhotics by approximately 50%. The activity of glucokinase was decreased in cirrhotic as compared in control patients (0.06 +/- 0.30 versus 0.42 +/- 0.21 U/ml hepatocytes, P < 0.05), the reduction being observed in both patients with alcoholic or biliary cirrhosis. We conclude that patients with alcoholic or biliary cirrhosis have decreased hepatic glycogen stores per volume of hepatocytes and per liver. Decreased activity of glucokinase may represent an important mechanism leading to this finding.

Prevalence of diabetes mellitus in patients with end-stage liver cirrhosis due to hepatitis C, alcohol, or cholestatic disease

Hepatic glycogen metabolism was investigated in genetically diabetic C57BL/KsJ-db/db mice during their development. Initially, the development of obesity, hyperglycemia, hyperinsulinemia, and hyperglucagonemia in these mice was examined, which illustrated that the diabetes progressed normally. Little difference in hepatic glycogen concentrations was observed, averaging approximately 50 and 60 mg/g liver in diabetic (db/db) and control heterozygote (db/+) mice, respectively. Glycogen synthase activity (total and a-form) was significantly elevated by 5 wk in the diabetic mice relative to controls and reached maximum levels (two-fold higher than controls) around 8-9 wk. This activity then slowly declined during the rest of the 15-wk period examined. Both phosphorylase a and total phosphorylase activities were also elevated by 5 wk, reaching levels twofold higher than controls. These activities did not decline at the end of this 15-wk period, but instead continued to slowly increase. Glycogen synthase a activity showed a positive correlation (r = 0.54, N = 144) with circulating levels of insulin, and a similar correlation was seen for phosphorylase a activity and plasma glucagon levels (r = 0.64, N = 72). Protein kinase and phosphoprotein phosphatase activities were also measured, but no differences were detected between diabetic and control mice. This longitudinal study clarifies some of the changes in hepatic glycogen metabolism that occur during the progression of diabetes in the db/db mouse and indicates a role for circulating insulin and glucagon concentrations on the steady-state activities of glycogen synthase and phosphorylase, respectively.

Glucose 6-phosphate (Glc-6-P) produced in cultured hepatocytes by direct phosphorylation of glucose or by gluconeogenesis from dihydroxyacetone (DHA) was equally effective in activating glycogen synthase (GS). However, glycogen accumulation was higher in hepatocytes incubated with glucose than in those treated with DHA. This difference was attributed to decreased futile cycling through GS and glycogen phosphorylase (GP) in the glucose-treated hepatocytes, owing to the partial inactivation of GP induced by glucose. Our results indicate that the gluconeogenic pathway and the glucokinase-mediated phosphorylation of glucose deliver their common product to the same Glc-6-P pool, which is accessible to liver GS. As observed in the treatment with glucose, incubation of cultured hepatocytes with DHA caused the translocation of GS from a uniform cytoplasmic distribution to the hepatocyte periphery and a similar pattern of glycogen deposition. We hypothesize that Glc-6-P has a major role in glycogen metabolism not only by determining the activation state of GS but also by controlling its subcellular distribution in the hepatocyte.

The Impact of Liver Disease on Growth and Nutrition

This study, using 13C nuclear magnetic resonance spectroscopy showed enrichment of glycogen carbon (C1) from 13C-labelled (C1) glucose indicating a direct pathway for glycogen synthesis from glucose in rainbow trout (Oncorhynchus mykiss) hepatocytes. There was a direct relationship between hepatocyte glycogen content and total glycogen synthase, total glycogen phosphorylase and glycogen phosphorylase a activities, whereas the relationship was inverse between glycogen content and % glycogen synthase a and glycogen synthase a/glycogen phosphorylase a ratio. Incubation of hepatocytes with glucose (3 or 10 mmol·1-1) did not modify either glycogen synthase or glycogen phosphorylase activities. Insulin (porcine, 10-8 mol·1-1) in the medium significantly decreased total glycogen phosphorylase and glycogen phosphorylase a activities, but had no significant effect on glycogen synthase activities when compared to the controls (absence of insulin). In the presence of 10 mmol·1-1 glucose, insulin increased % glycogen synthase a and decreased % glycogen phosphorylase a activities in trout hepatocytes. Also, the effect of insulin on the activities of % glycogen synthase a and glycogen synthase a/glycogen phosphorylase a ratio were more pronounced at low than at high hepatocyte glycogen content. The results indicate that in trout hepatocytes both the glycogen synthetic and breakdown pathways are active concurrently in vitro and any subtle alterations in the phosphorylase to synthase ratio may determine the hepatic glycogen content. Insulin plays an important role in the regulation of glycogen metabolism in rainbow trout hepatocytes. The effect of insulin on hepatocyte glycogen content may be under the control of several factors, including plasma glucose concentration and hepatocyte glycogen content.

Effect of starvation on hepatic glycogen metabolism and glucose homeostasis

Alcoholic liver damage–toxicity, autoimmunity and allergy

Do antinuclear antibodies in primary biliary cirrhosis patients identify increased risk for liver failure?

New treatments/targets for primary biliary cholangitis.

Prevalence and Predictors of Esophageal Varices in Patients With Primary Biliary Cirrhosis

Experience of liver transplantation (LT) in siblings is disseminated mainly through case reports (1–7). We performed a chart review using the electronic Finnish Liver Transplant Registry database, which contains clinical information on every LT recipient in Finland; 886 individuals from 1982 to April 10, 2013. These 886 LT recipients were treated for the following conditions: cholestatic liver disease (29.3%), other cirrhosis (25.6%), acute liver failure (17.5%), cancer (9.9%), congenital biliary atresia (7.3%), and metabolic disease (5.4%). Every LT patient in Finland is transplanted at Helsinki University Central Hospital, to which they return regularly for follow-up visits. We identified 14 individual deceased donor LT recipients, who had at least one sibling with LT, creating a prevalence of 1.6%. The study group comprised six pairs of siblings, mean age of 38 years and mean follow-up 8.8 years (Table 1). We recorded three deaths, attributed to severe noncompliance problems, sepsis, and hepatocellular carcinoma (HCC) recurrence.TABLE 1: Detailed demographic and liver transplantation-related data of 14 liver transplant recipients with at least one sibling a liver transplant recipient tooEtiology that led to end-stage liver disease in all except one set of siblings was recognized as complex hereditary genetic disease. The two brothers with cryptogenic cirrhosis and HCC were not diagnosed with a specific underlying liver disease. Their family history revealed that the paternal side of the family suffered from undefined liver problems. A third brother from the same family was diagnosed with liver cirrhosis and HCC. A colorectal malignancy was found, and he was deemed unsuitable for LT. “Familial biliary cirrhosis” patient data are shown in Table 1, 4A-D: all suffered from a cholestatic fibrotic liver disease that could not be classified as any known cholestatic liver disease. The disease could not be histologically differentiated from congenital liver fibrosis. Patients’ parents were healthy, and the patients did not have any associated abnormalities or kidney disease. All had shown first signs of the liver disease in their infancy or early childhood. The indication for LT was identical within the sibling group. The course of the disease that led to liver cirrhosis, end-stage liver disease, and ultimately to LT was similar within the sibling set, and the age at transplant were close to each other in most of the cases within the set. It seems that the presence or absence of rejection was shared between the siblings. However, we feel that our cohort is too small to make statistically reliable conclusions, given that the liver donors were so heterogeneous. During the early post-LT course, two brothers with alpha-1-antitrypsin deficiency experienced severe neurologic complications. Each brother was subjected to calcineurin inhibitors immediately after LT, as a part of our routine immunosuppressive protocol. Both experienced severe paresthesias, motor weaknesses, and altered mental status that was defined retrospectively as posterior reversible encephalopathy syndrome (PRES). The PRES is a well known but rare complication of calcineurin inhibitors that are used for immunosuppressive medication. The incidence of PRES in nonsibling population varies between 0.4% and 6% (8); however, its incidence in siblings is not known. We expected to find that LT was caused by alcohol use disorders; however, we did not find any evidence for this phenomenon in our group. Currently, 10% of LTs in Finland are caused by alcohol liver disease (ALD). Although there is a strong hereditary component for heavy drinking behavior (9), the development of ALD does not have a genetic predisposition (10). It seems plausible that ALD was not found in this study because it differs significantly from other chronic diseases recorded in this group, in which the disease prevalence in relatives is increased. We recorded that primary sclerosing cholangitis was the reason for LT in a sibling pair in this current study. According to a Scandinavian study, PSC is more frequent in first-degree relatives than that in the general population (11). Seven previously published articles reported LT in siblings, and these totaled 25 individuals. The indications for LT in pediatric cases have been type IV glycogen storage disease (3), Crigler-Najjar syndrome (2) and familial hypercholesterolemia (4). Most adult sibling LT recipients are diagnosed with amyloid metabolic disturbances (1, 6, 7). Other indications are related to altered cholesterol metabolism (5). We conclude that the prevalence of sibling LT recipients in Finland is low. This study revealed several unique features within sibling pairs; the etiologies that led to liver cirrhosis were mostly because of complex genetic abnormalities. The course of the disease leading to liver cirrhosis and tolerance to calcineurin inhibitors within a sibling set is analogous. Based on the results of this survey, we recommend a thorough review of the posttransplant course of the first LT sibling when the second sibling is opted for LT. Virve S. Koljonen Heikki H. Mäkisalo Transplantation and Liver Surgery Clinic Institute of Clinical Medicine Helsinki University Hospital Helsinki, Finland