Metagenomics of the Human Intestinal Tract
The number of microbes that are present on surfaces and in cavities of our body largely exceeds that of our own cells and the number of genes they encode largely exceeds that of our own genes. This complex and dynamic microbiota has a profound influence on human physiology and nutrition. Defining this dynamic diversity represents the next frontier of genomics. To progress towards this ambitious goal we focus on the microbiota of the intestinal tract, which is the most complex and plays a particularly important role in human health and well-being. The ensemble of the genomes of human-associated microorganisms represents the human metagenome. A detailed understanding of human biology will require not only knowledge of the human genome but also of the human microbial metagenome.
Our intestinal microbes
The microbes of the human intestine can reach up to ten trillion cells and represent a weight of two kilograms, exceeding that of our brain. They help us digest food, they synthesize vitamins and amino acids that are needed by our body, they protect us by educating the immune system to distinguish friends from foes. Many different diseases originate from microbial disorders. This is naturally the case of infectious diseases affecting the digestive system. But chronic diseases, which are steadily increasing in the modern societies, have also been associated with unusual changes in microbiota. Even the apparently psychological disorders such as autism may be related to an overgrowth of certain bacteria living in the intestine.
Expected achievements and their impact
The expected final achievements are the establishment of the methodology to characterize individual intestinal metagenomes and the discovery of associations between bacterial genes and human disease. This should pave the way for the development of novel diagnostic and prognostic tools, based on microbial genes, aiding preventive and personalized medicine. Furthermore, the unprecedented description of the human intestinal microbiota, its dynamics and its interaction with the human host that we aim to provide will lead to a much more complete understanding of global human biology.
Last but not least, by combining methodological and conceptual advances our project will result in, we expect to open avenues for reasoned modulation of our microbiota. The ability to characterize individual intestinal microbiota and follow its evolution with time, coupled to the understanding of the microbe/host interactions, should allow to explore the effects of factors such as food, environment and age on the dynamics of our microbial populations, and to develop interventions to optimize these populations. This should open novel possibilities to improve human health and well-being.