Over the past decade, more than US$1.7 billion has been spent on human microbiome research. Major projects are under way in the United States, the European Union, China, Canada, Ireland, South Korea and Japan. This investment has confirmed the importance of the microbiome to human health and development.
The dream of microbiome-based medicine requires a fresh approach — an ecological and evolutionary understanding of host-microbe interactions — argues Lita Proctor.
The finding that thousands of bacterial species (as well as viruses and fungi) live in people, and are an integral part of human biology, has challenged medicine’s view of microorganisms solely as agents of infectious disease.
The discovery that dietary fibre stimulates the particular groups of bacteria that produce key host-signalling molecules (such as short-chain fatty acids) is leading to the development of nutrition-based approaches to treating and restoring people’s microbiomes.
The transplantation of gut microbiota from one person to another has been found to be more than 90% effective in the treatment of recurring Clostridium difficile infections. The current care standard is repeated doses of antibiotics.
Some cancer treatments activate the immune system. A new approach to these has emerged with the discovery that efficacy is related to specific members of the patient’s gut microbiome.
Evolutionary biologists have argued for decades that human microbiome research would benefit from the evolutionary understanding provided by symbiosis research14. Certainly, human–microbiome systems share some of the features of highly regulated symbiotic associations. As just one example, a class of molecules produced only by bacteria (short-chain fatty acids) has a central role in host–microbe interactions. These molecules provide an energy source for the cells lining the human gut (most other cells depend on glucose). And they mediate interactions between different gut microbes, and between microbes and human cells.