Dietary fat enhanced chylomicron-mediated LPS translocation in a Caco-2 transwell model

Abstract Background There is increasing evidence that dietary fat, and especially saturated fat, promotes the absorption of lipopolysaccharide (LPS) via enhanced chylomicron production. The latter can subsequently transport LPS to other parts of the body, where it can induce low-grade chronic inflammation that links to various metabolic and gut-related diseases. To identify promising (food) compounds that can prevent or ameliorate LPS-related low grade inflammation, we developed and optimized an in vitro model for dietary fat-induced LPS translocation that mimics the in vivo situation and facilitates high-throughput screening. Results Differentiated Caco-2 cells were exposed to in vitro digested palm oil and sunflower oil in a dilution range, with or without starvation to optimize chylomicron production. To measure fat-induced chylomicron production, basolateral levels of the chylomicron-related marker apolipoprotein B (ApoB) were assessed. An optimal production was found after apical exposure to digested oils in a 1:50 dilution, preceded by one-week starvation (cultured without fetal bovine serum). Next, LPS was co-incubated in various concentrations with the digested oils and fat-induced LPS translocation to the basolateral side was assessed. We found that dietary fat-induced LPS translocation in Caco-2 cells was optimal after apical exposure to the digested oils in combination with 750ng/ml LPS. Subsequent co-incubation with the chylomicron blocker Pluronic L81 indicated that the fat-induced LPS translocation was at least partly mediated by chylomicrons. Conclusions We developed a robust Caco-2 cell model for dietary fat-induced LPS translocation that can be used for high-throughput screening of (food) compounds that can reduce LPS-related low grade inflammation.