Activation of Frizzled-7 attenuates blood-brain barrier disruption through Dvl/β-catenin/WISP1 signaling pathway after intracerebral hemorrhage in mice.

Destruction of blood-brain barrier (BBB) ​​is one of the main mechanisms of secondary brain injury following intracerebral hemorrhage (ICH). Frizzled-7 is a key protein expressed on the surface of endothelial cells that controls vascular permeability through the Wnt-canonical pathway involving WNT1-inducible signaling pathway protein 1 (WISPI). This study aimed to investigate the role of Frizzled-7 signaling in BBB preservation after ICH in mice. Adult CD1 mice were subjected to sham surgery or collagenase-induced ICH. Frizzled-7 activation or knockdown was performed by administration of Clustered Regularly Interspaced Palindromic Repeats (CRISPR) by intracerebroventricular injection at 48 h before ICH induction. WISP1 activation or WISP1 knockdown was performed to evaluate the underlying signaling pathway. Post-ICH assessments included neurobehavior, brain edema, BBB permeability, hemoglobin level, western blot and immunofluorescence. The brain expressions of Frizzled-7 and WISP1 significantly increased post-ICH. Frizzled-7 was expressed in endothelial cells, astrocytes, and neurons after ICH. Activation of Frizzled-7 significantly improved neurological function, reduced brain water content and attenuated BBB permeability to large molecular weight substances after ICH. Whereas, knockdown of Frizzled-7 worsened neurological function and brain edema after ICH. Activation of Frizzled-7 significantly increased the expressions of Dvl, β-Catenin, WISP1, VE-Cadherin, Claudin-5, ZO-1 and reduced the expression of phospho-β-Catenin. WISP1 knockdown abolished the effects of Frizzled-7 activation on the expressions of VE-Cadherin, Claudin-5 and ZO-1 at 24 h after ICH. Frizzled-7 activation potentially attenuated BBB permeability and improved neurological deficits after ICH through Dvl​​/β-Catenin/WISP1 pathway. Frizzled-7 may be a potential target for the development of ICH therapeutic drugs.

He W ，Lu Q ，Sherchan P ，Huang L ，Hu X ，Zhang JH ，Dai H ，Tang J ... -  《Fluids and Barriers of the CNS》

Endothelial TREM-1 receptor regulates the blood-brain barrier integrity after intracerebral hemorrhage in mice via SYK/β-catenin signaling.

Intracerebral hemorrhage (ICH) is a high mortality and disability stroke subtype. Destruction of the blood-brain barrier (BBB) is a crucial contributor to brain edema and neurological deficit after ICH. Triggering receptor expressed on myeloid cells 1 (TREM-1) has been reported to be expressed in endothelial cells, but its role in ICH remains unclear. This study aims to evaluate the role of TREM-1 on BBB permeability after ICH in mice. Two hundred and forty-two CD1 mice were used in this study. The ICH model was established by collagenase injection. LP17 was administered intranasally at 2 or 8 h after ICH to inhibit TREM-1. To explore the underlying mechanism, SYK activation CRISPR was administered intracerebroventricularly with LP17, and Anti-mouse TREM-1 rat IgG2a (a specific TREM-1 agonist) was injected intracerebroventricularly with R406 (a specific SYK inhibitor) intraperitoneally. Neurobehavioral outcome, brain water content, BBB permeability, and protein expression were evaluated. The expression level of the TREM-1 receptor increased rapidly as early as 6 h after ICH, and it was mainly expressed on the endotheliocytes in the neurovascular unit. Early and delayed administration of LP17 significantly decreased brain edema and improved neurobehavioral outcomes at 24 h after ICH. LP17 reduced the BBB permeability by increasing β-catenin, claudin-5 and ZO-1 expression. Furthermore, SYK activation CRISPR abolished the beneficial effect of LP17 on the expression of the above junction molecules. Meanwhile, R406 reversed the impact of the TREM-1 activator on the downregulation of β-catenin, claudin-5 and ZO-1 expression. This study demonstrated that TREM-1 deteriorated BBB permeability via modulating the expression of interendothelial junction molecules after ICH, and this regulation is partly mediated by the SYK/β-catenin signaling pathway.

Xie Y ，He W ，Ma L ，Ren R ，Yang S ，Lu Q ... -  《-》

Macrophage stimulating protein preserves blood brain barrier integrity after intracerebral hemorrhage through recepteur d'origine nantais dependent GAB1/Src/β-catenin pathway activation in a mouse model.

Blood brain barrier (BBB) disruption is an important contributor to brain edema and neurological deficits following intracerebral hemorrhage (ICH). Macrophage stimulating protein (MSP) is a hepatocyte growth factor-like protein that mediates its functions via activating receptor tyrosine kinase recepteur d'origine nantais (RON). Grb2-associated binder 1 (GAB1) is a docking protein that mediates downstream receptor signal transduction pathways. This study aimed to evaluate the role of MSP and RON activated signaling pathway in preserving BBB integrity after collagenase-induced ICH. ICH mice received recombinant human MSP (rhMSP) or rhMSP combined with siRNA knockdown of RON or GAB1. rhMSP was administered by intranasal route 1 h after ICH. Brain edema, neurobehavior, BBB tight junction protein expression, and BBB permeability were evaluated. The expression of endogenous MSP and p-RON was decreased after ICH. Exogenous rhMSP administration reduced brain edema, neurological deficits, BBB permeability, and increased the expression of tight junction proteins in ICH mice. rhMSP administration increased the expression of p-RON, p-GAB1, p-Src, nuclear β-catenin, and tight junction proteins after ICH. These effects were reversed with RON and GAB1 siRNA. We conclude that MSP activation of RON preserved BBB integrity via GAB-1/Src/β-catenin pathway, thereby reducing brain edema and neurological deficits after ICH in mice.

Lu T ，Wang Z ，Prativa S ，Xu Y ，Wang T ，Zhang Y ，Yu L ，Xu N ，Tang J ，You W ，Chen G ，Zhang JH ... -  《-》

Oxygen glucose deprivation-pretreated astrocyte-derived exosomes attenuates intracerebral hemorrhage (ICH)-induced BBB disruption through miR-27a-3p /ARHGAP25/Wnt/β-catenin axis.

Hou Y ，Xie Y ，Liu X ，Chen Y ，Zhou F ，Yang B ... -  《Fluids and Barriers of the CNS》

Lithium attenuates blood-brain barrier damage and brain edema following intracerebral hemorrhage via an endothelial Wnt/β-catenin signaling-dependent mechanism in mice.

Vasogenic cerebral edema resulting from blood-brain barrier (BBB) damage aggravates the devastating consequences of intracerebral hemorrhage (ICH). Although augmentation of endothelial Wnt/β-catenin signaling substantially alleviates BBB breakdown in animals, no agents based on this mechanism are clinically available. Lithium is a medication used to treat bipolar mood disorders and can upregulate Wnt/β-catenin signaling. We evaluated the protective effect of lithium on the BBB in a mouse model of collagenase IV-induced ICH. Furthermore, we assessed the effect and dependency of lithium on Wnt/β-catenin signaling in mice with endothelial deletion of the Wnt7 coactivator Gpr124. Lithium treatment (3 mmol/kg) significantly decreased the hematoma volume (11.15 ± 3.89 mm3 vs. 19.97 ± 3.20 mm3 in vehicle controls, p = 0.0016) and improved the neurological outcomes of mice following ICH. Importantly, lithium significantly increased the BBB integrity, as evidenced by reductions in the levels of brain edema (p = 0.0312), Evans blue leakage (p = 0.0261), and blood IgG extravasation (p = 0.0009) into brain tissue around the hematoma. Mechanistically, lithium upregulated the activity of endothelial Wnt/β-catenin signaling in mice and increased the levels of tight junction proteins (occludin, claudin-5 and ZO-1). Furthermore, the protective effect of lithium on cerebral damage and BBB integrity was abolished in endothelial Gpr124 knockout mice, suggesting that its protective effect on BBB function was mainly dependent on Gpr124-mediated endothelial Wnt/β-catenin signaling. Our findings indicate that lithium may serve as a therapeutic candidate for treating BBB breakdown and brain edema following ICH.

Song D ，Ji YB ，Huang XW ，Ma YZ ，Fang C ，Qiu LH ，Tan XX ，Chen YM ，Wang SN ，Chang J ，Guo F ... -  《-》