Obesity, Intestinal Gut Barrier and Microbiota: an Emerging Frontier on Energy Metabolism

Abstract

Background & Aims:An increasing interest in demonstrating differences between intestinal microbiota of obese and lean individuals has been observed during the last decade. The gut microbiota has been related to a number of metabolic abnormalities that could be associated not only to the pathophysiology of obesity, but also to several other highly prevalent diseases.As researches had shown differences in the prevalence of different bacteria in the gut of these individuals much importance has been given to microbiota composition along intestinal tract. However, few studies have related these findings to changes in the morphological and functional features of the intestinal epithelium.The intestinal barrier is a complex system and its integrity is essential to prevent against the entrance of harmful microorganisms or molecules to enter the bloodstream, such as LPS (bacterial lipopolysaccharide), a well-known trigger of the low grade inflammatory status. Increased intestinal permeability is one of the proposed mechanisms linking the gut microbiota with metabolic dysfunction, but there are few available data to define which one would be the cause or consequence. This review aims to show the current knowledge about the association between intestinal permeability in obesity and alterations in gut microbiota, in order to bring up a new vision of the pathophysiology of obesity and possibly promote future studies to better elucidate it. Methods: Pub Med searches were performed using terms "microbiota", "gut permeability" and "obesity". Articles related to intestinal permeability were selected. Results: Hyperactivation of endogenous cannabinoid system appears to augment gut permeability to LPS which, in turn, seems to enhance chronic inflammation status found in obesity state. Gut microbiota may play an important role in this process, through the regulation of the local immune system and also by regulating the amount of LPS which crosses the gut barrier. Conclusions: Lypopolyssacharide, endocanabinoid system and gut microbiota seem to play an important role in the development of obesity and emerge as a possible target for the treatment of obesity and correlated diseases.