RhoA/ROCK-2 Pathway Inhibition and Tight Junction Protein Upregulation by Catalpol Suppresses Lipopolysaccaride-Induced Disruption of Blood-Brain Barrier Permeability

Abstract

Lipopolysaccaride (LPS) directly or indirectly injures brain microvascular endothelial cells (BMECs) and damages the intercellular tight junction that gives rise to altered blood-brain barrier (BBB) permeability. Catalpol plays a protective role in LPS-induced injury, but whether catalpol protects against LPS-caused damage of BBB permeability and the underlying mechanism remain to be delineated. Prophylactic protection with catalpol (5 mg/kg, i.v.) consecutively for three days reversed the LPS-induced damage of BBB by decreased Evans Blue (EB) leakage and restored tight junctions in C57 mice. Besides, catalpol co-administrated with LPS increased BMECs survival, decreased their endothelin-1, TNF-Α and IL-6 secretion, improved transmembrane electrical resistance in a time-dependent manner, and in addition increased the fluorescein sodium permeability coefficient of BMECs. Also, transmission electron microscopy showed catalpol protective effects on tight junctions. Fluorescence staining displayed that catalpol reversed the rearrangement of the cytoskeleton protein F-actin and upregulated the tight junction protein of claudin-5 and ZO-1, which have been further demonstrated by the mRNA and protein expression levels of ZO-1, ZO-2, ZO-3, claudin-5, and occludin. Moreover, catalpol concurrently downregulated the mRNA and protein levels of RhoA, and ROCK2, the critical proteins in the RhoA/ROCK2 signaling pathway. This study thus indicated that catalpol, via inhibition of the RhoA/ROCK2 signaling pathway, reverses the disaggregation of cytoskeleton actin in BMECs and prevents down-regulation of junctional proteins, such as claudin-5, occludin, and ZO-1, and decreases endothelin-1 and inflammatory cytokine secretion, eventually alleviating the increase in LPS-induced BBB permeability.

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“…Nishioku et al reported that pericyte detachment and microglial activation may be involved in the mediation of LPS induced-BBB disruption due to the inflammatory responses in the damaged brain [29]. Our previous in vitro study revealed that LPS destructed the integrity between mice brain microvascular endothelial cells via disaggregating cytoskeleton actin and down-regulating tight junctional proteins, such as claudin-5, occludin, and ZO-1, as well as increasing the secretion of endothelin-1 and inflammatory cytokines secretion [25]. In consistent with our previous results, the disrupted ultrastructure of BBB and the down-regulation of tight junctional proteins were observed in mice after the LPS injury.…”

“…Evans blue perfusion analysis was performed as described previously [25]. At 48 h after the first administration of LPS, mice were intracardially perfused with prewarmed 0.9% NaCl briefly to wash out blood cells, followed by 0.5% Evans blue in cold 4% paraformaldehyde.…”

“…Transmission electron microscopy analysis was performed as described previously [25]. At 48 h after the first administration of LPS, mice in each group were anesthetized and perfused transcardially with 2.5% glutaraldehyde in 0.1 M PBS.…”

Switching of the Microglial Activation Phenotype Is a Possible Treatment for Depression Disorder

“…Depression symptoms were associated with greater cortisol levels and a more prolonged activation of the HPA axis and with an impaired from psychosocial stressors (Lopez-Duran et al, 2015 ). Under certain situations, stress can increases gut permeability, allowing the gut flora or their metabolites to cross the intestinal mucosa and stimulate the immune-brain system, eventually leading to the activation of immune cells (Feng et al, 2018 ), resulting in microglia activation that is accompanied by depressive-like behaviors (Depino, 2015 ).…”

Quantitatively relating brain endothelial cell–cell junction phenotype to global and local barrier properties under varied culture conditions via the Junction Analyzer Program

“…This result is very unlikely given the plethora of For (b, c), 232 ≤ N ≤ 244, where N is the number of cells, and for (d, e), N = 12, where N is the number of inserts pooled between the 0d and 1d cAMP conditions. The Mann-Whitney test was used to calculate significant differences for each parameter, where ns = p > 0.05, *p < 0.05, **p < 0.01, ***p < 0.001 and ****p < 0.0001 literary evidence suggesting otherwise [38][39][40][41][42]. Importantly, however, many of these reports are qualitatively correlative between immunostaining and permeability measurement, and not a quantitative correlation between permeability and junction presentation.…”