Highlights
• Secretion of mucin from the glands of Brunner promotes gut
Lactobacilli proliferation
• Central amygdala neurons stimulate Brunner’s glands via vagal nerves
• Stress inhibits the central amygdala, thereby suppressing Brunner’s glands activity
• Impaired gland activity compromises
Lactobacilli populations and host immunity
Summary
Negative psychological states impact immunity by altering the gut microbiome. However, the relationship between brain states and microbiome composition remains unclear. We show that Brunner’s glands in the duodenum couple stress-sensitive brain circuits to bacterial homeostasis. Brunner’s glands mediated the enrichment of gut
Lactobacillus species in response to vagus nerve stimulation. Cell-specific ablation of the glands markedly suppressed
Lactobacilli counts and heightened vulnerability to infection. In the forebrain, we mapped a vagally mediated, polysynaptic circuit connecting the central nucleus of the amygdala to Brunner’s glands. Chronic stress suppressed central amygdala activity and phenocopied the effects of gland lesions. Conversely, excitation of either the central amygdala or parasympathetic vagal neurons activated Brunner’s glands and reversed the effects of stress on the gut microbiome and immunity. The findings revealed a tractable brain-body mechanism linking psychological states to host defense.
Graphical abstract
