Abstract
The effect of two putative probiotic strains, Lactobacillus rhamnosus BFE5264 and Lactobacillus plantarum NR74, on the control of cholesterol efflux in enterocytes was assessed by focusing on the promotion of ATP-binding cassette sub-family G members 5 and 8 (ABCG5 and ABCG8). Differentiated Caco-2 enterocytes were treated with live bacteria, heat-killed bacteria, a bacterial cell wall fraction, and metabolites and were subjected to cholesterol uptake assay, mRNA analysis, and protein analyses. Following LXR-transfection by incubation with CHO-K1 cells in DNA-lipofectin added media, the luciferase assay was conducted for LXR analysis. Treatment of Caco-2 cells with L. rhamnosus BFE5264 (isolated from traditional fermented Maasai milk) and L. plantarum NR74 (isolated from Korean kimchi) resulted in the up-regulation of LXR, concomitantly with the elevated expression of ABCG5 and ABCG8. This was associated with the promotion of cholesterol efflux at significantly higher levels compared to the positive control strain L. rhamnosus GG (LGG). The experiment with CHO-K1 cells confirmed up-regulation of LXR-beta by the test strains, and treatment with the live L. rhamnosus BFE5264 and L. plantarum NR74 strains significantly increased cholesterol efflux. Heat-killed cells and cell wall fractions of both LAB strains induced the upregulation of ABCG5/8 through LXR activation. By contrast, LAB metabolites did not show any effect on ABCG5/8 and LXR expression. Data from this study suggest that LAB strains, such as L. rhamnosus BFE5264 and L. plantarum NR74, may promote cholesterol efflux in enterocytes, and thus potentially contribute to the prevention of hypercholesterolemia and atherosclerosis.