Lactobacillus rhamnosus strain GG reduces aflatoxin B1 transport, metabolism, and toxicity in caco-2 cells

The probiotic Lactobacillus rhamnosus GG is able to bind the potent hepatocarcinogen aflatoxin B, (AFB1) and thus potentially restrict its rapid absorption from the intestine. In this study we investigated the potential of GG to reduce AFB, availability in vitro in Caco-2 cells adapted to express cytochrome P-450 (CYP) 3A4, such that both transport and toxicity could be assessed. Caco-2 cells were grown as confluent monolayers on transmembrane filters for 21 days prior to all studies. AFB, levels in culture medium were measured by high-performance liquid chromatography. In CYP 3A4-induced monolayers, AFB(1) transport from the apical to the basolateral chamber was reduced from 11.1% +/- 1.9% to 6.4% +/- 2.5% (P = 0.019) and to 3.3% +/- 1.8% (P = 0.002) within the first hour in monolayers coincubated with GG (1 X 10(10) and 5 X 10(10) CFU/ml, respectively). GG (1 X 10(10) and 5 x 10(10) CFU/ml) bound 40.1% +/- 8.3% and 61.0% +/- 6.0% of added AFB(1) after 1 h, respectively. AFB, caused significant reductions of 30.1% (P = 0.01), 49.4% (P = 0.004), and 64.4% (P < 0.001) in transepithelial resistance after 24, 48, and 72 h, respectively. Coincubation with 1 X 10(10) CFU/ml GG after 24 h protected against AFB(1)-induced reductions in transepithelial resistance at both 24 h (P = 0.002) and 48 h (P = 0.04). DNA fragmentation was apparent in cells treated only with AFB, cells but not in cells coincubated with either 1 X 10(10) or 5 X 10(10) CFU/ml GG. GG reduced AFB1 uptake and protected against both membrane and DNA damage in the Caco-2 model. These data are suggestive of a beneficial role of GG against dietary exposure to aflatoxin.