Microbes and their metabolites control bidirectional signaling between the gut and the brain via pathways collectively known as the gut-brain axis. The gut-brain axis involves various pathways including the vagus nerve, with signaling impacting neural, endocrine, and immune processes. A growing number of chronic inflammatory conditions are tied to disruption of gut-brain axis signaling. These are my two favorite 2018 paper on the topic:

Microbiome–microglia connections via the gut–brain axis

Lead author: Sarkis Mazmanian, California Institute of Technology
 

The paper discusses how the gut microbiome plays a pivotal role in regulating microglial maturation and function. It also reviews a range of studies which demonstrate that bidirectional crosstalk between the gut and the brain may influence the pathogenesis of conditions ranging from autism, to Schizophrenia, to Parkinson’s.

Paper highlight: “Signals originating from the gut microbiota and transmitted to the brain have the potential to alleviate or exacerbate disease pathogenesis, changes that may operate through gut-mediated changes in microglial behavior. Thus, continued exploration of the intersection of microbiology, immunology, and neurobiology holds immense therapeutic promise.”

Lead author: Diego Bohorquez, Duke University

The team discovered a neural connection capable of rapidly transducing sensory signals from the gut to the brain. More specifically, they identified a type of enteroendocrine cell in the gut layer called the “neuropod cell.” These cells can communicate with sensory nerve fibers through direct cell-nerve contact. Neuropod cells can also secrete neuropeptides, and may subsequently convey information about nutrients in the gut to the brain by releasing quick-acting neurotransmitters.