Summary: Researchers have identified a new sensory pathway they call the “neurobiotic sense” — a gut-to-brain communication system in which specialized epithelial cells in the colon detect bacterial signals and relay real-time information to the brain to regulate appetite. These cells, known as neuropods, sense a common bacterial protein called flagellin and transmit an appetite-suppressing message through the vagus nerve. The discovery reveals a direct route by which the microbiome can influence feeding behavior and body weight.
The findings come from neuroscientists at Duke University School of Medicine and highlight how the gut-brain axis and the microbiome interact on a rapid, neural timescale. In experiments, mice lacking the receptor that senses flagellin continued to eat and gained weight, demonstrating the pathway’s role in controlling food intake. This research opens new directions for studying diet, obesity and mood disorders through the lens of microbe-driven neural signaling.
Key facts:
- Specialized colonic cells called neuropods detect microbial signals and communicate with the brain.
- The bacterial protein flagellin activates this pathway via the Toll-like receptor TLR5.
- Activation of neuropods reduces feeding through vagal sensory circuits; disruption leads to increased food intake and weight gain in mice.
Research context
Led by Diego Bohórquez, PhD, and M. Maya Kaelberer, PhD, the research demonstrates that neuropod cells in the colon express TLR5 and are sensitive to flagellin, a structural protein of bacterial flagella. When flagellin is present in the colonic lumen, neuropods respond by releasing peptide YY (PYY), which acts on vagal sensory neurons and reduces feeding. This neural circuit provides a mechanism for the gut to rapidly inform the brain about microbial activity, distinct from slower immune or metabolic responses.
The investigators tested the mechanism by administering a small amount of flagellin directly into the colon of fasted mice. The treated mice ate less than controls. In contrast, mice genetically engineered to lack TLR5 in these neuropod cells failed to change their intake after flagellin exposure and displayed greater weight gain over time. These results support the idea that flagellin is a microbial cue that, through TLR5 on neuropods, produces an immediate satiety signal conveyed by the vagus nerve.
What this means for the gut-brain axis and microbiome research
This discovery reframes part of the microbiome’s influence on host behavior: rather than acting only through immune activation, metabolites or hormonal changes, resident microbes can engage a neural sensory system at the intestinal epithelium to shape feeding behavior in real time. The authors propose the term “neurobiotic sense” for this interface where microbial patterns are detected by epithelial sensors and translated into neural signals that alter behavior.
The study suggests several important implications for human health and disease. First, diet-induced changes in microbial composition could alter the prevalence of flagellated bacteria and thereby influence appetite regulation through this neural pathway. Second, dysfunction in the neurobiotic sense might contribute to overeating and obesity, or affect mood and psychiatric conditions through altered gut-brain signaling. Finally, the mechanism provides a targeted framework to investigate how specific microbes or microbial products modulate neural circuits of appetite and behavior.
About this neuroscience and microbiome research news
Author: Fedor Kossakovski
Source: Duke University
Contact: Fedor Kossakovski – Duke University
Image: Image credited to Neuroscience News
Original research: Open access. “A gut sense for a microbial pattern regulates feeding” by Diego Bohórquez et al., published in Nature.
Abstract (summarized)
To coexist with resident microorganisms, hosts must detect and adjust behavior in response to microbial cues. In the intestine, nutrient sensing relayed to the brain via neuroepithelial circuits guides feeding choices. Until now, a neural sense that enables immediate responses to resident microbial patterns had not been described. This work shows that the microbial pattern flagellin stimulates TLR5 on peptide YY (PYY)-expressing colonic neuropod cells. PYY release onto NPY2R-expressing vagal nodose neurons reduces feeding. Mice lacking TLR5 in these cells consume more food and gain more weight. Flagellin acts through neuropod cells rather than directly on nerves, and it reduces feeding independently of immune activation, metabolic change or the presence of microbiota. The authors name this epithelial–neural detection system the neurobiotic sense, a mechanism that enables the host to adjust behavior in response to molecular patterns from its resident microorganisms.