Cooling Treatment Transiently Increases the Permeability of Brain Capillary Endothelial Cells Through Translocation of Claudin-5

Abstract

The blood-brain-barrier (BBB) is formed by different cell types, of which brain microvascular endothelial cells are major structural constituents. The goal of this study was to examine the effects of cooling on the permeability of the BBB with reference to tight junction formation of brain microendothelial cells. The sensorimotor cortex above the dura mater in adult male Wistar rats was focally cooled to a temperature of 5 °C for 1 h, then immunostaining for immunoglobulin G (IgG) was performed to evaluate the permeability of the BBB. Permeability produced by cooling was also evaluated in cultured murine brain endothelial cells (bEnd3) based on measurement of trans-epithelial electric resistance (TEER). Immunocytochemistry and Western blotting of proteins associated with tight junctions in bEnd3 were performed to determine protein distribution before and after cooling. After focal cooling of the rat brain cortex, diffuse immunostaining for IgG was observed primarily around the small vasculature and in the extracellular spaces of parenchyma of the cortex. In cultured bEnd3, TEER significantly decreased during cooling (15 °C) and recovered to normal levels after rewarming to 37 °C. Immunocytochemistry and Western blotting showed that claudin-5, a critical regulatory protein for tight junctions, was translocated from the membrane to the cytoplasm after cooling in cultured bEnd3 cells. These results suggest that focal brain cooling may open the BBB transiently through an effect on tight junctions of brain microendothelial cells, and that therapeutically this approach may allow control of BBB function and drug delivery through the BBB.

Endothelial Von Willebrand Factor Promotes Blood–Brain Barrier Flexibility and Provides Protection From Hypoxia and Seizures in Mice

“…44, 63, 64 The claudin-5 staining similar to that of ZO-1 suggesting that claudin-5 is also localized to the junction in the VWF −/− mice. The role of basement membrane proteins in tight junction protein expression is so far under-explored.…”

TGFβ1 exacerbates blood–brain barrier permeability in a mouse model of hepatic encephalopathy via upregulation of MMP9 and downregulation of claudin-5

“…Our studies focused only on the effects of TGFβ1 on claudin-5 expression and demonstrated that treatment of bEnd.3 cells with rTGFβ1 downregulated claudin-5 and led to the translocation of this protein from the cell membrane to the cytosol. Claudin-5 downregulation has been shown to lead to increased BBB permeability following hypoxia(35), focal cerebral cooling(36), and ischemia reperfusion injury(37). Also, other studies have found that TGFβ1 can lead to the direct downregulation of claudin-5(38).…”

Hypoxia/Aglycemia-Induced Endothelial Barrier Dysfunction and Tight Junction Protein Downregulation Can Be Ameliorated by Citicoline

“…ZO-1 and claudin-5 are the most important components for cell barrier integrity. Claudin-5 can greatly reduce dextran permeability and improve transendothelial electrical resistance [31], and plays an essential role in the earliest stage of CNS angiogenesis [32]. ZO-1 serves as a bridge between transmembrane proteins and skeleton proteins, and this interaction is important to the stability and function of endothelial barrier [33], [34].…”