The probiotic Lactobacillus rhamnosus GG (GG) is able to bind the potent hepatocarcinogen aflatoxin B1 (AFB1) and thus potentially restrict its rapid absorption from the intestine. In this study we investigated the potential of GG to reduce AFB1 availability in fully differentiated Caco-2 cell monolayers, adapted to express CYP3A4. To study intestinal transport, GG suspension (1x1010 CFU/ml) and AFB1 solution (150µM) were prepared in culture medium, added to differentiated Caco-2 cells grown on transmembrane filters, and aliquots of medium were taken and AFB1 determined by HPLC fluorescence detection. Furthermore, the integrity of the epithelial cell layer was monitored using transepithelial resistance (TER) measurements. AFB1 transport from the apical to basolateral chamber within the first hour was reduced from 11.1±1.9% in the absence of GG to 6.4±2.5% when co-incubated with GG (1x1010 CFU/ml) (p=0.019). During this time period GG bound 40.1±8.3% of added AFB1. AFB1 significantly reduced the TER in a time dependent manner. TER was reduced by 30.1% (p=0.01), 49.4% (p=0.004) and 64.4% (p<0.001) after 24, 48 and 32 hours respectively, compared to untreated controls. Co-incubation with GG protected against AFB1 induced TER reductions at 24 hours (p=0.002) and 48 hours (p=0.04), but not at 72 hours. These results indicate that GG can bind AFB1 in the Caco-2 model and are therefore suggestive that this binding would restrict AFB1 uptake in vivo. Aflatoxins may have a direct effect on the integrity of the intestine. In this model GG protected against the deleterious effect on TER caused by AFB1. The protective effects of this probiotic should be further explored in humans naturally exposed to aflatoxin through diet.
|Journal||Annals of Nutrition & Metabolism|
|Publication status||Published - Jul 2007|