Charting the enterotype in human disease and health

Animals and bacteria have been working together for about as long as they have co-existed, long before the advent of mankind. The bodies of our ancient ancestors offered protected, nutrientrich habitats for bacteria. In return, animals could take an evolutionary short-cut to developing new capabilities by ‘borrowing’ bacterial genes. In humans, bacterial genes can outnumber our own by about 100 to 1 and even though many merely help the bacteria survive, some are actually beneficial to us. Indeed, when gut bacteria assist with the digestion of e.g. dietary fibers, the metabolites they produce will exert an influence on an intricate network of molecular pathways in our bodies. As such, commensal bacteria exert a strong influence on the human immune system. Gut microbiota, in addition to genetics, therefore constitute a major factor in the onset and progression of complex disorders, ranging from obesity, cardiovascular disease, autoimmune disease, inflammation to neurological conditions and dementia. Recent efforts to determine the complex genetic composition of the gut microbiota in people with distinct geographical and ethnic backgrounds contributed to the identification of robust compositional clusters or ‘enterotypes’ that are not nation- or even continent specific. Therefore, the development of robust genetic profiling strategies for gut microbiota, i.e. 'enterotyping' is essential towards the development of novel diagnostics and cures in human disease.