Author Interviews, Brigham & Women's - Harvard, Microbiome, Nature / 21.06.2016 Interview with: Amir Bashan, PhD, and Yang-Yu Liu, PhD Channing Division of Network Medicine Brigham and Women’s Hospital and Harvard Medical School Boston, Massachusetts What is the background for this study? What are the main findings? Response:  We coexist with a vast number of microbes—our microbiota—that live in and on our bodies, and play important roles in human physiology and diseases. Our microbiota is inherently dynamic and changes throughout our lives. The changeability of our microbiota offers opportunities for microbiome-based therapies, e.g. fecal microbiota transplantation (FMT) and probiotic administration, to restore or maintain our healthy microbiota. Yet, our microbiota is also highly personalized and possess unique microbial “fingerprints” in both species assemblages and abundance profiles. This raises fundamental concerns regarding the efficacy and long-term safety of generic microbiome-based therapies. In particular, it is not known whether the underlying ecological dynamics of these communities, which can be parameterized by growth rates, and intra- and inter-species interactions in population dynamics models, are largely host-independent (i.e. universal) or host-specific. If the inter-individual variability reflects host-specific dynamics due to differences in host lifestyle, physiology or genetics, then generic microbiome manipulations may have unintended consequences, rendering them ineffective or even detrimental. In this case, we have to design truly personalized interventions, which need to consider not only the unique microbial state of an individual but also the unique dynamics of the underlying microbial ecosystem. In addition, host-specific microbial dynamics, if they exist, raise a major safety concern for FMT, because although the healthy microbiota are stable in the donor’s gut, they may be shifted to an undesired state in the recipient’s gut. Alternatively, microbial ecosystems of different subjects may exhibit universal dynamics, with the inter-individual variability mainly originating from differences in the sets of colonizing species. We can design general interventions to control the microbial state (in terms of species assemblage and abundance profile) of different individuals. (more…)