DNA Methylation of the ABO Promoter Underlies Loss of ABO Allelic Expression in a Significant Proportion of Leukemic Patients

Background: Loss of A, B and H antigens from the red blood cells of patients with myeloid malignancies is a frequent occurrence. Previously, we have reported alterations in ABH antigens on the red blood cells of 55% of patients with myeloid malignancies. Methodology/Principal Findings: To determine the underlying molecular mechanisms of this loss, we assessed ABO allelic expression in 21 patients with ABH antigen loss previously identified by flow cytometric analysis as well as an additional 7 patients detected with ABH antigen changes by serology. When assessing ABO mRNA allelic expression, 6/12 (50%) patients with ABH antigen loss detected by flow cytometry and 5/7 (71%) of the patients with ABH antigen loss detected by serology had a corresponding ABO mRNA allelic loss of expression. We examined the ABO locus for copy number and DNA methylation alterations in 21 patients, 11 with loss of expression of one or both ABO alleles, and 10 patients with no detectable allelic loss of ABO mRNA expression. No loss of heterozygosity (LOH) at the ABO locus was observed in these patients. However in 8/11 (73%) patients with loss of ABO allelic expression, the ABO promoter was methylated compared with 2/10 (20%) of patients with no ABO allelic expression loss (P = 0.03). Conclusions/Significance: We have found that loss of ABH antigens in patients with hematological malignancies is associated with a corresponding loss of ABO allelic expression in a significant proportion of patients. Loss of ABO allelic expression was strongly associated with DNA methylation of the ABO promoter.Tina Bianco-Miotto, Damian J. Hussey, Tanya K. Day, Denise S. O'Keefe and Alexander Dobrovi

Alcoholic Hepatitis Markedly Decreases the Capacity for Urea Synthesis.

Data on quantitative metabolic liver functions in the life-threatening disease alcoholic hepatitis are scarce. Urea synthesis is an essential metabolic liver function that plays a key regulatory role in nitrogen homeostasis. The urea synthesis capacity decreases in patients with compromised liver function, whereas it increases in patients with inflammation. Alcoholic hepatitis involves both mechanisms, but how these opposite effects are balanced remains unclear. Our aim was to investigate how alcoholic hepatitis affects the capacity for urea synthesis. We related these findings to another measure of metabolic liver function, the galactose elimination capacity (GEC), as well as to clinical disease severity.We included 20 patients with alcoholic hepatitis and 7 healthy controls. The urea synthesis capacity was quantified by the functional hepatic nitrogen clearance (FHNC), i.e., the slope of the linear relationship between the blood α-amino nitrogen concentration and urea nitrogen synthesis rate during alanine infusion. The GEC was determined using blood concentration decay curves after intravenous bolus injection of galactose. Clinical disease severity was assessed by the Glasgow Alcoholic Hepatitis Score and Model for End-Stage Liver Disease (MELD) score.The FHNC was markedly decreased in the alcoholic hepatitis patients compared with the healthy controls (7.2±4.9 L/h vs. 37.4±6.8 L/h, P<0.01), and the largest decrease was observed in those with severe alcoholic hepatitis (4.9±3.6 L/h vs. 9.9±4.9 L/h, P<0.05). The GEC was less markedly reduced than the FHNC. A negative correlation was detected between the FHNC and MELD score (rho = -0.49, P<0.05).Alcoholic hepatitis markedly decreases the urea synthesis capacity. This decrease is associated with an increase in clinical disease severity. Thus, the metabolic failure in alcoholic hepatitis prevails such that the liver cannot adequately perform the metabolic up-regulation observed in other stressful states, including extrahepatic inflammation, which may contribute to the patients' poor prognosis

Time course of compromised urea synthesis in patients with alcoholic hepatitis

<p><b>Objectives</b>: Alcoholic hepatitis (AH) markedly decreases the urea synthesis capacity. We aimed to investigate the time course of this compromised essential liver function in patients with AH and its relation to treatment and survival.</p> <p><b>Materials and methods</b>: Thirty patients with AH were included in a prospective cohort study. We measured the substrate-independent urea synthesis capacity, i.e., the functional hepatic nitrogen clearance (FHNC), in the patients at study entry and again at three months (survivors/available: <i>n</i> = 17). Patients with severe disease (Glasgow Alcoholic Hepatitis Score ≥9, <i>n</i> = 17) were randomized to receive either prednisolone or pentoxifylline and were in addition examined after 14 days (<i>n</i> = 9).</p> <p><b>Results</b>: FHNC (normal range = 25–45 L/h) was markedly decreased at study entry (median = 5.6 (IQR = 3.0–9.6) L/h) and increased by three-fold in survivors at three months (15.1 (12.0–22.9) L/h; <i>p</i> < .001). In patients with severe AH, FHNC was also increased after 14 days of pharmacologic treatment and showed the greatest increase in the patients taking prednisolone (prednisolone 25.4 (20.6–26.2) L/h vs. pentoxifylline 12.3 (8.0–15.3) L/h; <i>p</i> = .05). FHNC at study entry was lower in 90-day non-survivors than in survivors (<i>p</i> = .04).</p> <p><b>Conclusions</b>: The decrease in the urea synthesis capacity in patients with AH was the most marked in short-term non-survivors and partly recovered in survivors at three months. In patients on pharmacologic treatment, recovery was observed already after 14 days, and it was nearly complete in those on prednisolone. Thus, metabolic liver failure in AH seems to be prognostically important, is potentially reversible, and may recover more rapidly following treatment with prednisolone.</p

Baseline characteristics of the patients with alcoholic hepatitis and healthy controls.

<p>Baseline characteristics of the patients with alcoholic hepatitis and healthy controls.</p

Relationship between the functional hepatic nitrogen clearance and galactose elimination capacity.

<p>Relationship between the functional hepatic nitrogen clearance (FHNC) and galactose elimination capacity (GEC) in patients with non-severe (hollow circles) (GAHS<9, N = 8) and severe (circles) (GAHS≥9, N = 10) alcoholic hepatitis. No significant correlation was observed between the FHNC and GEC.</p

Functional hepatic nitrogen clearance in patients with non-severe and severe alcoholic hepatitis and healthy controls.

<p>Functional hepatic nitrogen clearance (FHNC) in patients with non-severe (GAHS<9, N = 9) and severe (GAHS≥9, N = 11) alcoholic hepatitis and healthy controls (N = 7). The solid horizontal lines indicate the mean values. The FHNC was decreased in the AH patients compared with the healthy controls (P<0.01) and the largest decrease was observed in those with severe AH (P<0.05).</p

Relationship between the functional hepatic nitrogen clearance and Model for End-Stage Liver Disease score.

<p>Relationship between the functional hepatic nitrogen clearance (FHNC) and Model for End-Stage Liver Disease (MELD) score in patients with non-severe (hollow circles) (GAHS<9, N = 9) and severe (circles) (GAHS≥9, N = 11) alcoholic hepatitis. The linear regression line shows the correlation (rho = -0.49; P<0.05).</p