Alcohol-induced generation of lipid peroxidation products in humans

Abstract

To address the hypothesis that elevated blood alcohol increases systemic oxidant stress, we measured urinary excretion of isoprostanes (iPs), free radical-catalyzed products of arachidonic acid. Ten healthy volunteers received acute doses of alcohol (Everclear-R) or placebo under randomized, controlled, double-blind conditions. Urinary iPF2a-III increased in a time- and dosage-dependent manner after dosing with alcohol, with the peak urinary iPF2a-III excretion correlating with the rise in blood alcohol. To determine whether oxidant stress was associated with alcohol-induced liver disease (ALD), we then studied the excretion of iP in individuals with a documented history of alcohol-induced hepatitis or alcohol-induced chronic liver disease (AC). Both urinary iPF2a-III and urinary iPF2a-VI were markedly increased in patients with acute alcoholic hepatitis. In general, urinary iPF2a-III was significantly elevated in cirrhotic patients, relative to controls, but excretion was more pronounced when cirrhosis was induced by alcohol than by hepatitis C. Excretion of iPF2a-VI, as well as 4-hydroxynonenal and the iPF2a-III metabolite, 2,3-dinor-5, 6-dihydro-iPF2a-III, was also increased in AC. Vitamin C, but not aspirin, reduced urinary iPs in AC. Thus, vasoactive iPs, which serve as indices of oxidant stress, are elevated in the urine in both acute and chronic ALD. Increased generation of iPs by alcohol in healthy volunteers is consistent with the hypothesis that oxidant stress precedes and contributes to the evolution of ALD.

Figures

Figure 1

Quantitation of 4-HNE in human urine. Five milliliters of urine was spiked with 5 ng of trideuterated 4-HNE. The upper trace (m/z 286) represents the internal standard; the lower trace (m/z 283) represents endogenous 4-HNE. Each ion trace shows 2 peaks (filled peak and asterisk-marked peak), which originate from the syn and anti isomers generated when the pentafluorobenzyloxime derivative is formed.

Figure 2

Time- and dose-dependent increase in excretion of iPF2α-III in healthy volunteers administered alcohol. Acute oral doses (240 mL) of alcohol or a control solution were administered under randomized, double-blind, controlled conditions. Urinary iPF2α-III increased significantly (P < 0.001) as a function of dose. Alcohol also increased urinary iPF2α-III in a time-dependent manner, with the 3 highest dose groups (P < 0.01) peaking in the fraction collected 0–6 hours after dosing.

Figure 3

The dose-related increment in iPF2α-III excretion in healthy volunteers. Alcohol significantly increased the maximal (vs. control) urinary iPF2α-III (P < 0.01) in a dose-dependent manner. Subsequent to ANOVA, paired comparisons indicated significant increases at the 2 highest doses.

Figure 4

Significant increases in urinary excretion of iPF2α-III in patients with cirrhosis due to alcoholism (ALD), viral hepatitis (HCV), or a combination of the 2 etiologies. Levels were significantly elevated in cirrhosis compared with controls. Excretion of iPF2α-III was most marked in acute alcoholic hepatitis.

Figure 5

Significant increases in urinary excretion of 2,3-dinor-5,6-dihydro-iPF2α-III (iPF2α-III–M), the putative dinor-dihydro metabolite of iPF2α-III, in patients with cirrhosis induced by alcohol (ALD), hepatitis C (HCV), or a combination of etiologies. Like the parent iPF2α-III, excretion of the metabolite was increased in all forms of cirrhosis, but particularly in ALD.

Figure 6

Significant increases in iPF2α-VI excretion in patients with cirrhosis due to alcoholism, hepatitis C virus (HVC), or a combination of the 2 etiologies. Levels were significantly elevated in cirrhosis compared with controls. iP excretion was most marked in acute alcoholic hepatitis.

Figure 7

Correlation excretion of urinary iPF2α-III and urinary iPF2α-VI in a subset of patients with cirrhosis of various etiologies (HCV, alcohol, and combined disease) and acute alcoholic hepatitis.