Increased frequencies of micronucleated reticulocytes and T-cell receptor mutation in Aldh2 knockout mice exposed to acetaldehyde

Abstract

-Aldehyde dehydrogenase-2 (ALDH2) metabolizes acetaldehyde produced from ethanol into acetate and plays a major role in the oxidation of acetaldehyde in vivo. About half of all Japanese people have inactive ALDH2. We generated homozygous Aldh2 null (Aldh2−/−) mice by gene targeting knockout as a model of ALDH2-deficient humans. To investigate the mutagenicity of acetaldehyde, a micronucleus assay and a T-cell receptor (TCR) gene mutation assay were performed in Aldh2−/− mice and wild-type (Aldh2+/+) mice exposed to acetaldehyde. The mice were continuously exposed to 125 and 500 ppm of acetaldehyde vapor for 2 weeks. Another group was orally administered 100 mg/kg once a day for 2 weeks continuously. The mice were killed after 2 weeks of exposure to acetaldehyde, and the frequency of micronucleated reticulocytes was measured by flow cytometry. We also observed the incidence of TCR gene mutations in T-lymphocytes by measuring the variant CD3 − CD4 + expression by flow cytometry. The frequency of micronucleated reticulocytes induced by acetaldehyde was significantly increased in Aldh2−/− mice, but not in Aldh2+/+ mice. TCR mutant frequency was also associated with acetaldehyde exposure in Aldh2−/− mice, especially after oral administration; however, it was not associated with acetaldehyde exposure in Aldh2+/+ mice. In conclusion, Aldh2−/− mice showed high sensitivity in the micronuclei and TCR mutation assays compared with Aldh2+/+ mice after exposure to acetaldehyde.

Mode of action-based risk assessment of genotoxic carcinogens

“…In the lung, there was a statistically significant increase in adduct levels only at the high concentration of 500 ml/m 3 with 171/10 8 bases (control 43.3/10 8 bases) for Aldh2-proficient and 283/10 8 bases (control 65.7/10 8 bases) for Aldh2 knockout mice (Oyama et al 2010). Micronucleus frequencies in reticulocytes were significantly increased after exposure to 125 or 500 ml acetaldehyde/m 3 and after oral administration of 100 mg acetaldehyde/kg bw for 2 weeks in Aldh2-knockout mice only (Kunugita et al 2008).…”

Orally administered Taenia solium Calreticulin prevents experimental intestinal inflammation and is associated with a type 2 immune response

“…Cells were centrifuged at 3000 rpm for 8 min at 4°C and 25 μl of RNAse, at a concentration of 1.2 mg/ml (Thermo scientific), were added. Cells were incubated at 37°C for 50 min to remove RNA [ 33 ]. Subsequently, cells were washed with 100 μl of BCB and centrifuged under the same conditions as described above.…”

Transgenic Mouse Models for Alcohol Metabolism, Toxicity, and Cancer

“…Further, they are more susceptible to ethanol-induced body weight loss [59], but show no change in mortality [60]. Aldh2 −/− mice are more sensitive to the toxic effects of inhaled acetaldehyde [61] and exhibit more frequent mutations in the T cell receptor site than their corresponding wild-type [62]. A single oral dose of ethanol in Aldh2 −/− downregulates the alcohol-metabolizing CYP2E1 mRNA [63], which suggests that there is compensation due to an abundance of acetaldehyde.…”