Blood-nerve barrier

The blood-nerve barrier is a cellular interface that regulates exchange between blood and the endoneurial space of peripheral nerves, helping maintain the nerve’s internal environment.

Endoneurial blood vessels: Capillaries and small vessels within the endoneurium, the connective tissue surrounding peripheral nerve fibers. Their endothelial cells form the principal vascular component of the barrier.
Peripheral nervous system: The nerves and ganglia outside the brain and spinal cord that connect the central nervous system with the body. The barrier is a specialized feature of this nervous system.
Guillain–Barré syndrome: A group of acute immune-mediated disorders in which peripheral nerves and nerve roots are damaged. Inflammation and barrier disruption can influence immune access to peripheral nerve tissue.
Blood-nerve barrier permeability: The degree to which substances can cross the blood-nerve barrier under particular conditions. Its regional and disease-related variation remains central to predicting nerve exposure.
Tight junction: A cell-to-cell junction that seals spaces between adjacent epithelial or endothelial cells. Tight junctions restrict passage between endoneurial endothelial cells.
Nerve fascicle: A bundle of nerve fibers enclosed by perineurium within a peripheral nerve. Fascicle boundaries help define the protected endoneurial compartment.
Diabetic neuropathy: Peripheral nerve damage associated with diabetes, often involving sensory loss, pain, or autonomic dysfunction. Diabetes can alter endoneurial vessels and compromise the nerve’s regulated environment.
Neuroinflammation: Inflammation involving nervous tissue, mediated by immune cells and inflammatory signaling molecules. Inflammatory signals can loosen barrier properties, but their effects differ by disease and timing.
Perineurium: The multilayered connective-tissue sheath that surrounds nerve fascicles in peripheral nerves. Its cell layers provide an additional diffusion barrier around nerve fascicles.
Schwann cell: A glial cell of the peripheral nervous system that ensheaths axons and forms myelin around many of them. Schwann cells maintain nerve fibers inside the compartment protected by the barrier.

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Chronic inflammatory demyelinating polyneuropathyRelated: Its immune regulation offers one route by which circulating immune activity can affect nerve tissue.