Lactobacillus rhamnosus Strain GG Reduces Aflatoxin B 1 Transport, Metabolism, and Toxicity in Caco-2 Cells

Abstract

The probiotic Lactobacillus rhamnosus GG is able to bind the potent hepatocarcinogen aflatoxin B ₁ (AFB ₁ ) and thus potentially restrict its rapid absorption from the intestine. In this study we investigated the potential of GG to reduce AFB ₁ 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 ₁ 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 × 10 ¹⁰ and 5 × 10 ¹⁰ CFU/ml, respectively). GG (1 × 10 ¹⁰ and 5 × 10 ¹⁰ CFU/ml) bound 40.1% ± 8.3% and 61.0% ± 6.0% of added AFB ₁ after 1 h, respectively. AFB ₁ 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 × 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 ₁ cells but not in cells coincubated with either 1 × 10 ¹⁰ or 5 × 10 ¹⁰ CFU/ml GG. GG reduced AFB ₁ 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.