Coordinated regulation of the metabolome and lipidome at the host-microbial interface

Abstract

The creative use of gnotobiotic animals, coupled with the development of modern metagenomic sequencing platforms and metabolomic profiling of biospecimens, has bestowed new insight into the remarkably intricate interface between the host mammal and its resident microbiota. As mutual benefactors, each partner exhibits evidence of adaptation: the host provides a hospitable habitat, giving consideration to its own species of origin, diet, genotype, geographical location, presence or absence of disease, and use of medications; the microbiota, in turn, configures its constituency, collective genome (microbiome), transcriptome, and metabolome to optimally suit its ecological niche. In this review, we discuss the mechanisms through which the gut microbiota and its host collaborate to regulate lipid metabolism, thereby influencing the metabolic response to nutrient intake and ultimately, the development of obesity and associated diseases such as lipotoxicity. These studies therefore demonstrate that the gut microbiota is an "environmental" influence whose synergistic interdependence with its host strongly suggests that we are in fact "supraorganisms."

Fig. 1. The gut microbiota affects host lipid metabolism

The gut microbiota affects lipid uptake and chylomicron formation by modulating bile acid transformations and gut transit time. Furthermore the gut microbiota is instrumental in fermenting complex polysachharides to short chain fatty acids that may act as a lipogenic substrates in the liver. In addition, the gut microbiota suppresses expression of Angiopoietin-like protein 4 (Angptl4) in the intestinal mucosa, which increases LPL mediated triglyceride storage in adipose tissue and reduces serum triglyceride levels. Angptl4 also promote fatty acid oxidation by a yet unidentified receptor.