A team of researchers at Oregon State University have made an essential advance in understanding the roles that gut bacteria play in human health. When scientists learn the mechanisms by which gut microbes affect the health of their hosts opens the doors to the development of better, more personalized diagnostic methods and therapies.
The focus of other studies is on how the composition of the microbiome, i.e., which organisms are present and in what amounts, associated with health in general or various disease.
With a Ph.D., student, Courtney Armour leading the study, the OSU research goes a step further by looking not just at which organisms are in the microbiome, but also what functions they might be performing. The team published their findings in mSystems.
Working under microbiology and statistics researcher Thomas Sharpton in OSU's College of Science, Armour analyzed data and findings from eight different studies encompassing seven various diseases in a metagenomic meta-analysis.
Metagenomics is defined as the study of genetic material recovered directly from environmental samples; in this case, human fecal samples, as opposed to from organisms cultured in a lab. A meta-analysis is a statistical technique for combining data from multiple studies.
Armour, Sharpton, and their collaborators performed the meta-analysis involved metagenomic data from nearly 2,000 stool samples collected for studies involving colorectal cancer. Crohn's disease, liver cirrhosis, obesity, rheumatoid arthritis, type 2 diabetes, and ulcerative colitis.
There are more than 10 trillion microbial cells in the gut microbiota from about 1,000 different bacteria species. The microbial ecosystem stays in balance via cell-to-cell signaling and the release of antimicrobial peptides that keep in check individual bacterial clades.
Gut microbes interact with their human host as well, sometimes in ways that promote health, other times in ways that contribute to disease development. Dysbiosis, or imbalance in the microbiome is commonly associated with detrimental effects on the health of the host.
Sharpton added that in their study, they looked at how gut microbiome protein family richness, composition, and dispersion related to the disease. Proteins are large, complex molecules that do most of the work in cells and are required for the structure, function, and regulation of tissues and organs.
Explaining further, Sharpton said that their analysis of protein family richness revealed that patients with Crohn's disease, obesity, type 2 diabetes or ulcerative colitis feature a smaller number of protein families compared to their respective control populations. On the other hand, people with colorectal cancer had a more significant amount of microbiome protein families than their controls.
Sharpton concluded that they are trying to disentangle cause and effect to resolve these needles in haystacks and find the links between the microbiome and health. Future research can leverage this new knowledge to test microbiome functions against the presence and severity of various diseases.
