Disentangling Host-Microbiota Regulation of Lipid Secretion by Enterocytes: Insights from Commensals Lactobacillus paracasei and Escherichia coli

The specific contribution of each bacterial species within a complex microbiota to the regulation of host lipid metabolism remains largely unknown. Using two model commensal microorganisms, L. paracasei and E. coli , we demonstrated that both bacterial species impacted host lipid metabolism in a diet-dependent manner and, notably, that L. paracasei -colonized mice but not E. coli -colonized mice resisted high-fat-diet-induced body weight gain. In addition, we set up cellular models of fatty acid absorption and secretion by enterocytes cocultured with bacteria and showed that, in vitro , both L. paracasei and E. coli inhibited lipid secretion, through increased intracellular fat storage and enhanced lipid catabolism, respectively.