Reactive oxygen species alter brain endothelial tight junction dynamics via RhoA, PI3 kinase, and PKB signaling

Abstract

The blood-brain barrier (BBB) prevents the entrance of circulating molecules and immune cells into the central nervous system. The barrier is formed by specialized brain endothelial cells that are interconnected by tight junctions (TJ). A defective function of the BBB has been described for a variety of neuroinflammatory diseases, indicating that proper regulation is essential for maintaining brain homeostasis. Under pathological conditions, reactive oxygen species (ROS) significantly contribute to BBB dysfunction and inflammation in the brain by enhancing cellular migration. However, a detailed study about the molecular mechanism by which ROS alter BBB integrity has been lacking. Here we demonstrate that ROS alter BBB integrity, which is paralleled by cytoskeleton rearrangements and redistribution and disappearance of TJ proteins claudin-5 and occludin. Specific signaling pathways, including RhoA and PI3 kinase, mediated observed processes and specific inhibitors of these pathways prevented ROS-induced monocyte migration across an in vitro model of the BBB. Interestingly, these processes were also mediated by protein kinase B (PKB/Akt), a previously unknown player in cytoskeleton and TJ dynamics that acted downstream of RhoA and PI3 kinase. Our study reveals new insights into molecular mechanisms underlying BBB regulation and provides novel opportunities for the treatment of neuroinflammatory diseases.

Ascorbic Acid Prevents Blood–Brain Barrier Disruption and Sensory Deficit Caused by Sustained Compression of Primary Somatosensory Cortex

“…In addition, direct treatment of 4-HNE or hydrogen peroxide to brain endothelial cells has been shown to impair the BBB integrity (Lee et al, 2004;Mertsch et al, 2001). In this study, both the NADPH oxidase inhibitor apocynin and the xanthine oxidase inhibitor allopurinol prevented the BBB disruption, which is consistent with the findings from other laboratories that these two oxidases contribute to the BBB dysfunction (Kahles et al, 2007;Schreibelt et al, 2007;Sheth et al, 2003). Collectively, these results indicate that ROSs have a detrimental role in the BBB integrity.…”

“…In this regard, ROS seems to have a more important role than reactive nitrogen species in the BBB disruption in our model. Superoxide, one of the major ROSs, has been shown to regulate the endothelial tight junction proteins and increase the BBB permeability through RhoA, phosphatidylinositol 3 kinase (PI3 kinase), and the protein kinase B (PKB/Akt) signaling pathway (Schreibelt et al, 2007;Sheth et al, 2003). Activation of protein tyrosine kinase by superoxide has also been implicated in dissociation of occluding-ZO-1 and E-cadherin-b-catenin complexes from the cytoskeleton (Rao et al, 2002).…”

“…The astrocytic reaction and its spatial relation to the microvessels were also analyzed. Conversely, reactive oxygen species (ROS; e.g., superoxide, hydrogen peroxide, and hydroxyl radical) and reactive nitrogen species (e.g., nitric oxide (NO) and peroxynitrite) have been shown to affect endothelial cell permeability (Parathath et al, 2006;Schreibelt et al, 2007). Thus, we examined the expressions of the biomarkers 3-nitrotyrosine (3-NT) for protein nitration and 4-hydroxynonenal (4-HNE) for lipid peroxidation, both of which have been extensively used to evaluate the free radicalinduced cellular damage (Choi et al, 2007).…”

Resolvin D1 reduces deterioration of tight junction proteins by upregulating HO-1 in LPS-induced mice

“…30,31 In the pathogenesis of ALI, extensive cytokines and ROS were released. 32 Inflammation initiated by oxidative stress can be regulated by the RvD1.…”

Molecular Determinants of the Interaction between Clostridium perfringens Enterotoxin Fragments and Claudin-3

“…Cell (24). When monolayers reached maximum resistance (ϳ1500 ⍀) 10 g/ml GST-CPE-(116 -319) or GST were introduced into the medium.…”