Gut microbiota as a regulator of energy homeostasis and ectopic fat deposition: mechanisms and implications for metabolic disorders.

PURPOSE OF REVIEW: To examine the role of gut microbiota in the regulation of host energy homeostasis and its role in the pathogenesis of obesity, diabetes and nonalcoholic fatty liver disease (NAFLD).

RECENT FINDINGS: Experimental models highlight several mechanisms connecting gut microbiota to host energy metabolism: increased energy harvesting from the diet, regulation of appetite through gut peptide, secretion, regulation of tissue-free fatty acid composition and uptake, storage and oxidation, modulation of intestinal barrier by glucagon-like peptide-2 secretion, activation of innate immunity and hepatic fibrogenesis through the lipopolysaccharide (LPS)-toll-like receptor-4 axis.Gut microbiota manipulation through antibiotics, prebiotics and probiotics yields encouraging results for the treatment of obesity, diabetes and NAFLD in animal models, but data in humans are currently scarce.

SUMMARY: Gut microbiota manipulation yielded encouraging results for the treatment of different metabolic disorders in experimental models. However, changing intestinal microbiota may be more difficult in free-living individuals compared to standardized laboratory models, and its long-term consequences are unknown. To safely and effectively change human gut microflora, future research should highlight the complex hormonal, immunomodulatory and metabolic mechanisms underlying microbiota-host interactions in different tissues and candidate treatments should be evaluated in well designed trials with patient-oriented end-points.