Induction of cytochrome P450 2E1 increases hepatotoxicity caused by Fas agonistic Jo2 antibody in mice

Abstract

Cytochrome P450 2E1 (CYP2E1) may be a central pathway in generating oxidative stress, reactive oxygen species, and causing hepatotoxic injury by alcohol and various hepatotoxins. This study evaluated the ability of CYP2E1 to potentiate or synergize the hepatotoxicity of Fas in vivo. C57BL/6 mice were injected intraperitoneally with pyrazole (Pyr) to induce CYP2E1. Then, 16-hour fasted mice were administered agonistic Jo2 anti-Fas antibody ip. Other mice were treated with Pyr or Jo2 alone. Levels of serum aminotransferase were 8.3-and 6.3-fold higher in the Pyr/Jo2 group compared with Jo2 alone, respectively. Histological evaluation of liver showed more extensive acidophilic necrosis and severe pathological changes in the Pyr/Jo2-treated mice. DNA fragmentation and caspase-8 and -3 activities were more elevated in the Pyr/Jo2 group compared with Jo2 alone. CYP2E1 activity and protein levels were higher in the Pyr/Jo2 group than in Jo2 alone. Levels of inducible nitric oxide synthase, 3-nitrotyrosine protein adducts, malondialdehyde, and protein carbonyls were also higher in the Pyr/Jo2 group compared with Jo2 alone. Glutathione and activities of catalase and Cu-Zn superoxide dismutase were decreased in the Pyr/Jo2 group. Administration of chlormethiazole, an inhibitor of CYP2E1, to the Pyr/Jo2-treated mice caused a significant decrease of alanine aminotransferase and liver pathological changes in association with a decrease in CYP2E1 protein and activity. In conclusion, enhanced hepatotoxicity of Fas was found in mice with elevated levels of CYP2E1. We speculate that overexpression of CYP2E1 might synergize and increase the susceptibility to Fas induced-liver injury.(HEPATOLOGY 2005;42:400-410.)

Ethanol-induced cytochrome P4502E1 causes carcinogenic etheno-DNA lesions in alcoholic liver disease

“…Furthermore, a significant decrease of alanine aminotransferase, CYP2E1 activity, and protein level, as well as an alleviation of alcohol-specific histological features of liver damage, were noted in mice treated with pyrazole (a CYP2E1 inducer) when CMZ was co-administered. 32 Our current data extend these findings by demonstrating that blocking human CYP2E1 activity in HepG2 cells by CMZ prevents ethanol-induced DNA damage.…”

Overexpression of CYP2E1 enhances sensitivity of HepG2 cells to Fas-mediated cytotoxicity

“…4 CYP2E1 is one of the important hepatic metabolic enzymes. It was a central pathway in the production of oxidative stress and ROS.…”

“…Caspase-8, -9 and -3 activities were determined by measuring proteolytic cleavage of the added substrate. 4 Briefly, the proluminescent substrates Z-IETD-AFC, AC-LEHD-AFC, and AC-DEVD-AMC (Calbiochem, La Jolla, CA) can be cleaved by caspase-8, caspase-9 and caspase-3, respectively. Samples were diluted at 1:100 in reaction buffer containing 100 mM HEPES (pH 7.5), 10% sucrose, 10 mM dithiothreitol, 0.5 mM EDTA, and 0.02 mM of the caspase substrate and incubated at 30°C in a shaking water bath overnight.…”

“…16,17 Interestingly, treatment of mice with pyrazole to induce CYP2E1 was verified to increase hepatotoxicity produced by Fas agonistic Jo2 antibody. 4 Wang et al further reported that CYP2E1 was also involved in ethanol/Jo2-mediated liver injury in mice. 18 However, whether CYP2E1 can synergize with Fas to promote apoptosis or injury in HCC remains unknown.…”

“…Fas-mediated apoptosis may occur in an autocrine or paracrine fashion via a soluble form of the ligand. 4 It is important to note that not all Fas bearing cells are susceptible to Fas-mediated killing. Normal liver cells are known to express Fas, and to be susceptible to Fas-mediated apoptosis.…”