Lactobacillus rhamnosus CNCMI-4317 modulates Fiaf/Angptl4 in intestinal epithelial cells and impacts host metabolism

Background & Objectives: Identification of news targets for metabolic diseases treatment or prevention was required. In this context, FIAF/ANGPTL4 appeared as a crucial regulator of energy homeostasis. Lactobacilli are often considered to display beneficial effect for their hosts, acting on regulatory pathway. The aim of the present work was to study the effect of several lactobacilli strains on Fiaf gene expression in human intestinal epithelial cells (IECs) and on mice tissues to decipher the underlying mechanisms. Subjects & Methods: Nineteen lactobacilli strains have been tested on HT-29 cells for their ability to regulate Fiaf gene expression by RT-qPCR. In order to determine regulated pathways, we analyzed the whole genome transcript of IECs. We then validate in vivo bacterial effect using C57BL/6 mono-colonized mice fed with normal chow. Results: We identified one strain (L. rhamnosus CNCMI-4317, p<0,001) modulating Fiaf expression in IECs. This regulation relies potentially on bacterial surface-exposed molecules and seems to be PPAR-γ independent and PPAR-α dependent. Functional analysis revealed that most of the significant different expressed genes affected by this strain were involved in cellular function and maintenance, lymphoid tissues structure and development or lipids metabolism. The regulation of immune system and lipids and carbohydrates metabolism was also confirmed by overrepresentation of Gene Ontology terms analysis. In vivo, the strain increased FIAF protein (p<0,05) in the serum and tend to up regulate it in distal small intestine (p=0,14). Moreover, the observed induction of IL-7 (p<0,05) suggested a role on immune cells regulation. Conclusion: We showed that the strain induce Fiaf expression in human IECs and in mice intestine. This bacterial effect is accompanied by modulation of immune response and metabolism providing such a bacterial strain an interesting candidate to modulate metabolic and low grade inflammation disorders. A total of 28 microarrays were analysed: 8 independent cultures of HT-29 cells at different passage number for L. rhamnosus CNCMI-4317 treatment, rosiglitazone (positive control) and DMEM (negative control) and four replicates for L. rhamnosus CNCMI-2493. We used the Illumina human genome microarrays (HumanHT-12 v4 Expression BeadChip Kit, SanDiego,USA). For each sample, 750ng of labeled cDNA was synthesized from total RNA using Ovation PicoSL WTA System v2 and Encore BiotinIL Module kits (Nugen Technologies, Inc. Leek, The Netherlands).