Endothelial brain

The blood-brain barrier (BBB) forms a physiological barrier between the central nervous system and the blood circulation. It consists of glial cells and a special species of endothelial cells, which form tight junctions between each other thereby inhibiting paracellular transport. In addition, the endothelial cells of the BBB express a variety of ABC-transporters to protect the brain tissue against toxic metabolites and xenobiotics. The BBB is permeable to water, glucose, sodium chloride and non-ionised lipid-soluble molecules but large molecules such as peptides as well as many polar substances do not readily permeate the battier. 

Although mast cells and basophils probably account for >90% of stored histamine in the body, histamine is also present in platelets, enterochromaffin-like cells, endothelial cells, and neurons. Histamine can act as a neurotransmitter in the brain. Histaminergic nerves have their cell bodies within a very small area of the brain (the magnocellular nuclei of the posterior hypothalamus) but have axons in most areas of the forebrain. There is also evidence for axons projecting into the spinal (Fig. 1) cord. Finally, there is evidence that histamine synthesis can be induced in tissues undergoing rapid tissue growth and repair. In certain neonatal tissues (e.g. liver), the rate of synthesis of this unstored diffusable histamine (termed nascent histamine) is profound and may point to a role for histamine is cell proliferation. 

Expression (Human) Tissues Leukocytes, thymus, spleen, liver, ovary Cells PBLs, neutrophils,T-cells, dendritic cells, mast cells, eosinophils, macrophages, leukocytes Tissues spleen, small intestine, placenta, lung smooth muscle, Cells bronchial smooth muscle, CD34+ hemapoietic progenitor cells, monocytes, macrophages, mast cells, eosinophils, neutrophils, PBLs, human umbilical vein endothelial cells Tissues, heart, skeletal muscle, spleen, brain, lymp node, adrenal medulla, lung, human pumonary/ saphenous vein Cells monocytes, macrophages, mast cells, eosinophils, cardiac muscle, coronary artery, PBLs... 

Expression (Mouse) Tissues lungs, Cells myeloid leukocytes, neutrophils, T-cells, macrophages, mast cells, eosinophils Tissues lung, skin, small intestine Cells macrophages, fibroblasts, leukocytes Tissues lung, skin, brain, small intestine, spleen Cells macrophages, fibroblasts, endothelial cells, leukocytes... 

Endothelial NO Synthase (eNOS) expression is relatively specific for endothelial cells. However, the isozyme has also been detected in certain neurons of the brain, in syncytiotrophoblasts of human placenta and in LLC-PKi kidney tubular epithelial cells. 

Paris D, Ait-Ghezala G, Mathura VS, Patel N, Quadros A, Laporte V, et al. Anti-angiogenic activity of the mntant Dntch A(beta) peptide on human brain microvascular endothelial cells. Brain Res Mol Brain Res 2005 136 212-30. 

Biemacki K, Prat A, Blain M, Antel JP (2001) Regulation of Thl and Th2 lymphocyte migration by human adult brain endothelial cells. J Neuropathol Exp Neurol 60 1127-1136 Bleul CC, Farzan M, Choe H, Parolin C, Clark-Lewis I, Sodroski J, Springer TA (1996a) The lymphocyte chemoattractant SDF-1 is a ligand for LESTR/fusin and blocks HIV-1 entry. Nature 382 829-833... 

Nakamuta S, Endo H, Higashi Y, Kousaka A, Yamada H, Yano M, Kido H (2008) Human immunodeficiency virus type 1 gpl20-mediated disruption of tight junction proteins by induction of proteasome-mediated degradation of zonula occludens-1 and -2 in human brain microvascular endothelial cells. J Neurovirol 14 186-195... 

In most parts of the body, substances, other than large molecular ones like proteins, are filtered from the blood into the extracellular space through gaps between endothelial cells in the capillary wall. Such gaps are much narrower, almost nonexistent, in brain capillaries and it is likely that any filtering is further reduced by the manner in which astrocytes pack around the capillaries. This constraint is known as the... 

Dzenko KA, Song L, Ge S, et al. CCR2 expression by brain microvascular endothelial cells is critical for macrophage transendothelial migration in response to CCL2. Microvasc Res 2005 90(l-2) 53-64. 

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