Fig. 2.

The inflammatory reflex. The current understanding of the inflammatory reflex, an immune-regulatory vagus nerve circuit, is that sensory nerve fibers, e.g., afferent vagus nerve branches, report on localized cytokine levels and inflammation in the periphery. This information is processed in the brain stem, which generates efferent signals that travel through motor fibers in the vagus nerve and activate the adrenergic splenic nerve, which releases norepinephrine in the spleen. Specialized choline acetyltransferase-expressing T cells (ChAT⁺ T cells) release ACh in response to norepinephrine and inhibit macrophage cytokine production by activating their α₇-nicotinic ACh receptors (α₇nAChRs). β₂AR, β₂-adrenergic receptors.