fig2

Figure 2. Proposed routes of BEV-mediated gut-brain communication. Vesicle or cargo delivery, peripheral immune and metabolic signaling, and vagal involvement may contribute to homeostatic or pathological CNS responses. The BBB and blood-CSF barrier represent distinct candidate interfaces. Solid arrows indicate observations supported in selected experimental models; dashed arrows indicate proposed delivery steps. Intact-vesicle entry into brain tissue remains unresolved, and vagotomy-sensitive effects do not establish axonal BEVs transport. BEVs: Bacterial extracellular vesicles; BBB: blood-brain barrier; CNS: central nervous system; CSF: cerebrospinal fluid.