title: [Blood-nerve barrier: structure and function].
abstract: The blood-nerve barrier (BNB) is a dynamic interface between the endoneurial microenvironment and surrounding extracellular space or blood contents, and is localized the innermost layer of multilayered ensheathing perineurium and endoneurial microvessels. Since the BNB is a key structure controlling the internal milieu of the peripheral nerve parenchyma, adequate understanding of the BNB is crucial for developing treatment strategies for human peripheral nervous system disorders, including Guillain-Barré syndrome, chronic inflammatory demyelinating polyneuropathy, and diabetic and various metabolic/toxic neuropathies. However, fewer studies have been conducted on the BNB, if we compare against the number of studies on the blood-brain barrier. This is because of the lack of adequate human cell lines originating from the BNB. In our laboratory, human immortal cell lines from the BNB, namely, the endothelial cell line and pericyte cell line, have recently been established and vigorous investigations of their biological and physiological properties are now underway. Pericytes constituting the BNB were found to possess robust ability of controlling BNB integrity via secretion of various cytokines and growth factors including bFGF, VEGF, GDNF, BDNF, and angiopoietin-1. Unknown soluble factors secreted by pericytes also contribute to the upregulation of claudin-5 in endothelial cells in the BNB and thus, strengthen the barrier function of the BNB. In diabetic neuropathy, pericytes were shown to regulate the vascular basement membrane, while AGEs were shown to induce basement membrane hypertrophy and disrupt the BNB by increasing the autocrine secretion of VEGF and TGF-beta from pericytes. In this review article, we discuss the macroscopic and microscopic anatomy of the human BNB as well as the molecular mechanisms of mononuclear cell infiltration across the BNB.
authors: Department of Neurology and Clinical Neuroscience, Yamaguchi University Graduate School of Medicine, Yamaguchi, Japan.
authors: Takashi
authors: T
authors: Kanda