Differential effects of hydrocortisone and TNFα on tight junction proteins in an in vitro model of the human blood–brain barrier

Abstract

Homeostasis of the central nervous system (CNS) microenvironment is maintained by the blood-brain barrier (BBB) which regulates the transport of molecules from blood into brain and back. Many disorders change the functionality and integrity of the BBB. Glucocorticoids are being used sucessfully in the treatment of some disorders while their effects on others are questionable. In addition, conflicting results between clinical and experimental experience using animal models has arisen, so that the results of molecular studies in animal models need to be revisited in an appropriate in vitro model of the human BBB for more effective treatment strategies. Using the human brain microvascular endothelial cell line hCMEC/D3, the influence of glucocorticoids on the expression of barrier constituting adherens junction and tight junction transmembrane proteins (VE-cadherin, occludin, claudins) was investigated and compared to other established BBB models. In hCMEC/D3 cells the administration of glucocorticoids induced expression of the targets occludin 2.75 ± 0.04-fold and claudin-5 up to 2.32 ± 0.11-fold, which is likely to contribute to the more than threefold enhancement of transendothelial electrical resistance reflecting barrier tightness. Our analyses further provide direct evidence that the GC hydrocortisone prevents endothelial barrier breakdown in response to pro-inflammatory stimuli (TNFα administration), which could be demonstrated to be partly based on maintenance of occludin levels. Our studies strongly suggest stabilization of BBB function as a mode of GC action on a molecular level in the human brain vasculature.

Glucocorticosteroids Increase Cell Entry by Hepatitis C Virus

“…Together, these results agree with previous findings implicating GCs with upregulation of SR-BI and occludin [38][39][40] and provide strong evidence that prednisolone enhances HCV entry via GC signalling-dependent upregulation of these HCV entry factors.…”

Nanoparticle accumulation and transcytosis in brain endothelial cell layers

“…7 In cell culture, the hCMEC/D3 cell line maintains a contact-inhibited monolayer, exhibits robust proliferation in response to endothelial growth factors and grows indefinitely without phenotypic de-differentiation. 40 Moreover, these cells express chemokine receptors in response to inflammatory cytokines, a series of tight junction proteins 41 and multidrug resistant proteins, e.g., Pglycoprotein (P-gp). 42 Thus, hCMEC/D3 BBB models are an excellent candidate for blood-brain barrier function and transport studies.…”

Role of Caspases in Cytokine-Induced Barrier Breakdown in Human Brain Endothelial Cells

“…TNF receptor 1 (TNFR1) is expressed constitutively on almost every nucleated cell type and tissue, whereas the expression of TNF receptor 2 (TNFR2) is highly regulated with prominent expression in cells of the immune system and endothelium, including BECs (13,14). Increased levels of TNF-a have been reported not only to modulate endothelial TJs and cytoskeleton rearrangement in BECs (15,16) but also to evoke an increase in caspase-3 activation driving BECs into apoptosis (13,17). More recently, a study has proposed that primary cultures of human BECs are resistant to cell death mediated by TNF-a (18).…”