HUMAN SUPERORGANISM

HUMAN SUPERORGANISM


Human beings can be considered as “superorganisms” as a result of their close symbiotic associations with the gut microbiota. Superorganism metabolism involves integration of truly indigenous metabolic processes (coded in the host genome) with those of the microbiome. This results in extensive transgenomic cometabolism of many substrates including those involved in host metabolic regulation. The superorganism concept represents an important paradigm shift in understanding human biology and is likely to have a significant impact on the future of disease prevention and therapy. Recent works have shown that the exact human microbiome composition varies between healthy people and also between lean and obese individuals, and further, that the microbiome composition is responsive to dietary modulation for weight reduction. “Top-down”systems biology analysis of metabolic profiles of human baby microbiota and normal microbiota associated mice revealed that absorption, storage, and metabolism of dietary lipids were specifically modulated by the microbiome. Moreover, the induction of type 2 diabetes and obesity with a high-fat diet in rats has been shown to correlate with the predose metabolic patterns associated with differences in gut bacterial activities, indicating the importance of the microbiome in host predisposition to diseases. Recent work showed that gut microbiome was probably responsible in part for the systemic response to Schistosoma mansoni infection in mice. Disruptions of choline metabolism caused by changes in symbiotic gut microbiota may play an active role in the development of insulin resistance and nonalcoholic fatty liver disease in high-fat diet experiments with a mouse strain genetically predisposed to these disease traits (. Responses of individual animals and humans to drug treatments can also be strongly influenced by gut microbiome composition, because the microbiome provides not only complementary metabolic pathways for drugs, but is also a source of pharmacologically active secondary metabolites that can activate mammalian liver enzyme systems. The importance of gut microbiota to host metabolism may best be illustrated by the fact that genetically homogeneous animals can have diverse metabolic phenotypes when they have structurally different gut microbiota. It has also been shown that identical twins still had significant differences in their gut microbiota although they shared much higher similarity for gut microbiota structures than genetically unrelated married couples. The unique combination of gut bacteria in each animal may thus have an important role in their host's metabolism because they are adding new dimensions to functional diversity at the whole-organism level on host genetics, which includes participating the development of pathophysiology and providing complimentary metabolic pathways for drugs and diets. In light of the recent findings on the relationships between gut bacterial composition and the obese host phenotype, understanding gut bacterial dynamics in relation to host physiology and pathology has become an important part of future personalized health care solutions.