Molecular signatures for the dynamic process of establishing intestinal host-microbial homeostasis: potential for disease diagnostics?

Purpose of review: The dynamic interplay of the intestinal microbiota and host has been the focus of many studies because of its impact on the health status in human life. Recent reports on the time-resolved immune and metabolic interactions between the host and microbiota, as well as the molecular signatures that mark this communication during the process of establishing a host–microbial relationship, are addressed here. Recent findings: During microbial colonization, the progressive impact of de-novo introduction of the gut microbiota on the host's physiology is tightly controlled by highly intertwined regulatory networks and achieves an efficient and balanced interplay between the host and its developing microbial community. Recent findings from germ-free mouse models have unravelled core transcriptional, metabolic and microbial signatures, which are proposed to orchestrate the molecular responses during the establishment of the multifaceted state of intestinal host–microbe homeostasis. Summary: Exploring the time-resolved dynamics of the host responses to the newly colonizing gut microbiota provides mechanistically critical understanding of the sequential host–microbe response cascades that lead to a homeostatic relationship. Thereby, these approaches can provide novel diagnostic tools and therapeutic targets, or either of the two, in humans for specific disorders associated with intestinal dysbiosis and loss of homeostasis