Protective effect of aged garlic extract (AGE) on the apoptosis of intestinal epithelial cells caused by methotrexate

Purpose  Methotrexate (MTX) causes intestinal damage, resulting in diarrhea. The side effects often disturb the cancer chemotherapy. We previously reported that AGE protected the small intestine of rats from the MTX-induced damage. In the present paper, the mechanism of the protection of AGE against the MTX-induced damage of small intestine was investigated, using IEC-6 cells originating from rat jejunum crypt. Methods  The viability and apoptosis of IEC-6 cells were examined in the presence of MTX and/or AGE. Results  The viability of IEC-6 cells exposed to MTX was decreased by the increase of MTX concentration. The MTX-induced loss of viable IEC-6 cells was almost completely prevented by the presence of more than 0.1% AGE. In IEC-6 cells exposed to MTX, the cromatin condensation, DNA fragmentation, caspase-3 activation and cytochrome c release were observed. These were preserved to the control levels by the presence of AGE. MTX markedly decreased intracellular GSH in IEC-6 cells, but the presence of AGE in IEC-6 cells with MTX preserved intracellular GSH to the control level. IEC-6 cells in G2/M stage markedly decreased 72 h after the MTX treatment, which was preserved to the control level by the presence of AGE. These results indicated that AGE protected IEC-6 cells from the MTX-induced damage. Conclusions  The MTX-induced apoptosis of IEC-6 cells was shown to be depressed by AGE. AGE may be useful for the cancer chemotherapy with MTX, since AGE reduces the MTX-induced intestinal damage.