Oleoylethanolamide-producing Lactobacillus paracasei F19 improves metabolic and behavioral disorders by restoring intestinal permeability and microbiota-gut-brain axis in high-fat diet-induced obese male mice

: Metabolic and mood disorders elicited by chronic exposure of high-fat diet (HFD) are often associated with intestinal dysbiosis and persistent low-grade inflammation in the small intestine. This leads to remodeling of the epithelial barrier with disruption of the neuroepithelial circuits that control energy homeostasis by the gut-brain axis. Therefore, therapies that restoreintestinal microbial niche and barrier function are promising candidates to counter peripheral metabolic challenges that affect behaviors controlled by the brain. The endogenous oleoylethanolamine (OEA) was found to shape the intestinal microbiota profile towards a "lean-like phenotype", ameliorating pathological profiles of metabolic diseases. Further, OEA displays beneficial effects in several cognitive paradigms and preserves the epithelial barrier integrity, acting as an intestinal "gate-keeper". Here, we developed an "intestinal OEA factory" for the in-situ and controlled release of OEA by using a probiotic-based delivery system. We engineered the Lactobacillus paracasei F19 (LP) to express the human N-acylphosphatidylethanolamine-preferring phospholipase D (NAPEpld) gene and to produce OEA in response to dietary ultra-low oleate supply. We treated 12-week HFD male mice with oleate-probiotic formulations and assessed their impact on metabolic and behavioral dysfunctions, and microbiota-gut-brain signaling after 8 weeks of treatment. NAPE-expressing LP (pNAPE-LP) led to significant reduced weight loss and improved metabolic dysfunction in HFD-treated mice. Further, a parallel improvement in depressive- and anxiety-like phenotypes was associated with the duodenal barrier function retrieval, the restoration of the Firmicutes/Bacteroidetes ratio, and an increase in beneficial bacteria, such as Lactobacillus, Prevotella, and Parabacteroides. The HFD-driven changes both in the enteric and central nervous system were prevented by pNAPE-LP/oleate treatment. Collectively, our data suggest that these effects were mediated by the oleate-dependent release of OEA by pNAPE-LP since no significant effects were observed in HFD mice treated with the native probiotic alone (pLP). This oleate-regulated delivery system of OEA is a safe and efficient probiotic-based strategy for the treatment of metabolic syndrome and related behavioral disorders.