The sonic hedgehog pathway mediates Tongxinluo capsule‐induced protection against blood‐brain barrier disruption after ischaemic stroke in mice

Chinese patent medicine Tongxinluo: A review on chemical constituents, pharmacological activities, quality control, and clinical applications

BACKGROUND

Cardiovascular and cerebrovascular disease (CCVD) is the leading cause of morbidity and mortality worldwide, imposing a significant economic burden on individuals and societies. For the past few years, Traditional Chinese Medicine (TCM) has attracted much attention due to its advantages such as fewer side effects in the treatment of CCVD. TXL has shown great promise in the treatment of CCVD.

PURPOSE

This paper aims to provide a comprehensive introduction to TXL, covering its chemical constituents, quality control, pharmacological properties, adverse reactions, and clinical applications through an extensive search of relevant electronic databases while discussing its current challenges and provides opinions for future study.

METHODS

The following electronic databases were searched up to 2023: "TXL", "CCVD", "Chemical constituents", "Quality control" and "Pharmacological properties" were entered as keywords in PubMed, Web of Science, Google Scholar and China National Knowledge Infrastructure Database and WANFANG DATA databases. The PRISMA guidelines were followed in this review process.

RESULTS

Studies have confirmed that TXL is effective in treating patients with CCVD and has fewer adverse effects. The aim of this review is to explore TXL anti-CCVD effects in relation to oxidative stress, lipid metabolism and enhanced cardiac function. This review also provides additional information on safety issues.

CONCLUSION

TXL plays a key role in the treatment of CCVD by regulating various pathways such as lipid metabolism, oxidative stress and inflammation. However, further clinical trials and animal experiments are needed to provide more evidence and recommendations for its clinical application. This article provides an overview of TXL research to inform and inspire future studies.

Crosstalk Among Glial Cells in the Blood-Brain Barrier Injury After Ischemic Stroke

Blood-brain barrier (BBB) is comprised of brain microvascular endothelial cells (ECs), astrocytes, perivascular microglia, pericytes, neuronal processes, and the basal lamina. As a complex and dynamic interface between the blood and the central nervous system (CNS), BBB is responsible for transporting nutrients essential for the normal metabolism of brain cells and hinders many toxic compounds entering into the CNS. The loss of BBB integrity following stroke induces tissue damage, inflammation, edema, and neural dysfunction. Thus, BBB disruption is an important pathophysiological process of acute ischemic stroke. Understanding the mechanism underlying BBB disruption can uncover more promising biological targets for developing treatments for ischemic stroke. Ischemic stroke-induced activation of microglia and astrocytes leads to increased production of inflammatory mediators, containing chemokines, cytokines, matrix metalloproteinases (MMPs), etc., which are important factors in the pathological process of BBB breakdown. In this review, we discussed the current knowledges about the vital and dual roles of astrocytes and microglia on the BBB breakdown during ischemic stroke. Specifically, we provided an updated overview of phenotypic transformation of microglia and astrocytes, as well as uncovered the crosstalk among astrocyte, microglia, and oligodendrocyte in the BBB disruption following ischemic stroke.

Neuroprotective effects of Aframomum pruinosum seed extract against stroke in rat: Role of antioxidant and anti-inflammatory mechanisms

BACKGROUND

Stroke is a major cause of disability and neurological impairment worldwide. Effective prevention and management strategies are needed to reduce its burden. This study aimed to investigate the therapeutic effect of the seed ethanolic extract of Aframomum pruinosum (EEAP) on stroke and its related motor and cognitive deficits in rats.

MATERIALS AND METHODS

Stroke was induced by either middle cerebral artery occlusion (MCAO) or bilateral common carotid artery occlusion (BCCAO). In the MCAO model, rats received EEAP (75, 150, or 300 mg kg-1) or N-acetyl-L-cysteine (100 mg kg-1) orally for one week before 2 h of occlusion, followed by reperfusion. Twenty-four hours after ischemia, brain was collected for infarct size using 2, 3, 5 -TriphenylTetrazolium Chloride (TTC) staining, oxidative stress markers and inflammatory cytokines (TNF-α, IL-1β) measurements. In the BCCAO model, rats underwent occlusion for 30 min and received EEAP or quercetin (25 mg kg-1) for 7 days post-induction. Behavioral parameters were evaluated at the end of the treatment. Oxidative stress and inflammatory markers were measured in the cerebrum and cerebellum.

RESULTS

MCAO caused significant brain infarction, and increased lipid peroxidation, TNF-α and IL-1β contents. EEAP, rich in nerolidol, prevented these changes in a dose-dependent manner. BCCAO impaired the neurological function, mobility, and muscle strength of rats. It also increased lipid peroxidation and inflammatory cytokines in the cerebellum. EEAP significantly ameliorated these impairments.

CONCLUSION

EEAP exerts preventive and curative neuroprotective effects against ischemic stroke and its associated motor impairments at least partially through its antioxidant and anti-inflammatory properties, and its nerolidol content.

Knockdown of Smox protects the integrity of the blood-brain barrier through antioxidant effect and Nrf2 pathway activation in stroke

Once an ischemic stroke occurs, reactive oxygen species (ROS) and oxidative stress degrade the tight connections between cerebral endothelial cells resulting in their damage. The expression of antioxidant genes may be enhanced, and ROS formation may be reduced following Nrf2 activation, which is associated with protection against ischemic stroke. Overexpression of spermine oxidase (Smox) in the neocortex led to increased H2O2 production. However, how Smox impacts the regulation of the blood-brain barrier (BBB) through antioxidants has not been examined yet. We conducted experiments both in the cell level and in the transient middle cerebral artery occlusion (tMCAO) model to evaluate the effect of Smox siRNA lentivirus (si-Smox) knockdown on BBB protection against ischemic stroke. Mice treated with si-Smox showed remarkably decreased BBB breakdown and reduced endothelial inflammation following stroke. The treatment with si-Smox significantly elevated the Bcl-2 to Bax ratio and decreased the production of cleaved caspase-3 in the tMCAO model. Further investigation revealed that the neuroprotective effect was the result of the antioxidant properties of si-Smox, which reduced oxidative stress and enhanced CD31+ cells in the peri-infarct cortical areas. Of significance, si-Smox activated Nrf2 in both bEnd.3 cells and tMCAO animals, and blocking Nrf2 with brusatol diminished the protective effects of si-Smox. The study findings suggest that si-Smox exerts neuroprotective effects and promotes angiogenesis by activating the Nrf2 pathway, thus decreasing oxidative stress and apoptosis caused by tMCAO. As a result, si-Smox may hold potential as a therapeutic candidate for preserving BBB integrity while treating ischemic stroke.

Dl-3-n-butylphthalide promotes angiogenesis in ischemic stroke mice through upregulating autocrine and paracrine sonic hedgehog

Dl-3-n-butylphthalide (NBP) is a small-molecule drug used in the treatment of ischemic stroke in China, which is proven to ameliorate the symptoms of ischemic stroke and improve the prognosis of patients. Previous studies have shown that NBP accelerates recovery after stroke by promoting angiogenesis. In this study, we investigated the mechanisms underlying the angiogenesis-promoting effects of NBP in ischemic stroke models in vitro and in vivo. OGD/R model was established in human umbilical vein endothelial cells (HUVECs) and human brain microvascular endothelial cells (HBMECs), while the tMCAO model was established in mice. The cells were pretreated with NBP (10, 50, 100 µM); the mice were administered NBP (4, 8 mg/kg, i.v.) twice after tMCAO. We showed that NBP treatment significantly stimulated angiogenesis by inducing massive production of angiogenic growth factors VEGFA and CD31 in both in vitro and in vivo models of ischemic stroke. NBP also increased the tubule formation rate and migration capability of HUVECs in vitro. By conducting the weighted gene co-expression network analysis, we found that these effects were achieved by upregulating the expression of a hedgehog signaling pathway. We demonstrated that NBP treatment not only changed the levels of regulators of the hedgehog signaling pathway but also activated the transcription factor Gli1. The pro-angiogenesis effect of NBP was abolished when the hedgehog signaling pathway was inhibited by GDC-0449 in HUVECs, by Sonic Hedgehog(Shh) knockdown in HUVECs, or by intracerebroventricular injection of AAV-shRNA(shh)-CMV in tMCAO mice. Furthermore, we found that HUVECs produced a pro-angiogenic response not only to autocrine Shh, but also to paracrine Shh secreted by astrocytes. Together, we demonstrate that NBP promotes angiogenesis via upregulating the hedgehog signaling pathway. Our results provide an experimental basis for the clinical use of NBP.

Trans-Compartmental Regulation of Tight Junction Barrier Function

Tight junctions (TJs) are the most apical components of junctional complexes in epithelial and endothelial cells. Barrier function is one of the major functions of TJ, which restricts the ions and small water-soluble molecules from passing through the paracellular pathway. Adherens junctions (AJs) play an important role in cell-cell adhesion and cell signaling. Gap junctions (GJs) are intercellular channels regulating electrical and metabolic signals between cells. It is well known that TJ integral membrane proteins, such as claudins and occludins, are the molecular building blocks responsible for TJ barrier function. However, recent studies demonstrate that proteins of other junctional complexes can influence and regulate TJ barrier function. Therefore, the crosstalk between different cell junctions represents a common means to modulate cellular activities. In this review, we will discuss the interactions among TJ, AJ, and GJ by focusing on how AJ and GJ proteins regulate TJ barrier function in different biological systems.

Microglia and the Blood-Brain Barrier: An External Player in Acute and Chronic Neuroinflammatory Conditions

Microglia are the resident immune cells of the central nervous system that guarantee immune surveillance and exert also a modulating role on neuronal synaptic development and function. Upon injury, microglia get activated and modify their morphology acquiring an ameboid phenotype and pro- or anti-inflammatory features. The active role of microglia in blood-brain barrier (BBB) function and their interaction with different cellular components of the BBB-endothelial cells, astrocytes and pericytes-are described. Here, we report the specific crosstalk of microglia with all the BBB cell types focusing in particular on the involvement of microglia in the modulation of BBB function in neuroinflammatory conditions that occur in conjunction with an acute event, such as a stroke, or in a slow neurodegenerative disease, such as Alzheimer's disease. The potential of microglia to exert a dual role, either protective or detrimental, depending on disease stages and environmental conditioning factors is also discussed.

The role of traditional herbal medicine for ischemic stroke: from bench to clinic-A critical review

BACKGROUND

Ischemic stroke (IS) is a leading cause of death and severe long-term disability worldwide. Over the past few decades, considerable progress has been made in anti-ischemic therapies. However, IS remains a tremendous challenge, with favourable clinical outcomes being generally difficult to achieve from candidate drugs in preclinical phase testing. Traditional herbal medicine (THM) has been used to treat stroke for over 2,000 years in China. In modern times, THM as an alternative and complementary therapy have been prescribed in other Asian countries and have gained increasing attention for their therapeutic effects. These millennia of clinical experience allow THM to be a promising avenue for improving clinical efficacy and accelerating drug discovery.

PURPOSE

To summarise the clinical evidence and potential mechanisms of THMs in IS.

METHODS

A comprehensive literature search was conducted in seven electronic databases, including PubMed, EMBASE, the Cochrane Central Register of Controlled Trials, the Chinese National Knowledge Infrastructure, the VIP Information Database, the Chinese Biomedical Literature Database, and the Wanfang Database, from inception to 17 June 2022 to examine the efficacy and safety of THM for IS, and to investigate experimental studies regarding potential mechanisms.

RESULTS

THM is widely prescribed for IS alone or as adjuvant therapy. In clinical trials, THM is generally administered within 72 h of stroke onset and are continuously prescribed for over 3 months. Compared with Western medicine (WM), THM combined with routine WM can significantly improve neurological function defect scores, promote clinical total effective rate, and accelerate the recovery time of stroke with fewer adverse effects (AEs). These effects can be attributed to multiple mechanisms, mainly anti-inflammation, antioxidative stress, anti-apoptosis, brain blood barrier (BBB) modulation, inhibition of platelet activation and thrombus formation, and promotion of neurogenesis and angiogenesis.

CONCLUSIONS

THM may be a promising candidate for IS management to guide clinical applications and as a reference for drug development.

Interactions between glial cells and the blood-brain barrier and their role in Alzheimer's disease

Alzheimer's disease (AD), which is an irreversible neurodegenerative disorder characterized by senile plaques and neurofibrillary tangles, is the most common form of dementia worldwide. However, currently, there are no satisfying curative therapies for AD. The blood-brain barrier (BBB) acts as a selective physical barrier and plays protective roles in maintaining brain homeostasis. BBB dysfunction as an upstream or downstream event promotes the onset and progression of AD. Moreover, the pathogenesis of AD caused by BBB injury hasn't been well elucidated. Glial cells, BBB compartments and neurons form a minimal functional unit called the neurovascular unit (NVU). Emerging evidence suggests that glial cells are regulators in maintaining the BBB integrity and neuronal function. Illustrating the regulatory mechanism of glial cells in the BBB assists us in drawing a glial-vascular coupling diagram of AD, which may offer new insight into the pathogenesis of AD and early intervention strategies for AD. This review aims to summarize our current knowledge of glial-BBB interactions and their pathological implications in AD and to provide new therapeutic potentials for future investigations.

Emerging therapeutic targets for cerebral edema

INTRODUCTION

Cerebral edema is a key contributor to death and disability in several forms of brain injury. Current treatment options are limited, reactive, and associated with significant morbidity. Targeted therapies are emerging based on a growing understanding of the molecular underpinnings of cerebral edema.

AREAS COVERED

We review the pathophysiology and relationships between different cerebral edema subtypes to provide a foundation for emerging therapies. Mechanisms for promising molecular targets are discussed, with an emphasis on those advancing in clinical trials, including ion and water channels (AQP4, SUR1-TRPM4) and other proteins/lipids involved in edema signaling pathways (AVP, COX2, VEGF, and S1P). Research on novel treatment modalities for cerebral edema [including recombinant proteins and gene therapies] is presented and finally, insights on reducing secondary injury and improving clinical outcome are offered.

EXPERT OPINION

Targeted molecular strategies to minimize or prevent cerebral edema are promising. Inhibition of SUR1-TRPM4 (glyburide/glibenclamide) and VEGF (bevacizumab) are currently closest to translation based on advances in clinical trials. However, the latter, tested in glioblastoma multiforme, has not demonstrated survival benefit. Research on recombinant proteins and gene therapies for cerebral edema is in its infancy, but early results are encouraging. These newer modalities may facilitate our understanding of the pathobiology underlying cerebral edema.

Chinese medicine Tongxinluo capsule protects against blood-brain barrier disruption after ischemic stroke by inhibiting the low-density lipoprotein receptor-related protein 1 pathway in mice

BACKGROUND

Chinese medicine Tongxinluo capsule (TXL) has been extensively used to treat ischemic stroke in China, and one of its mechanisms is to protect against blood brain barrier (BBB) disruption after stroke. However, the underlying protective mechanisms are not fully illuminated. It is reported that the low-density lipoprotein receptor-related protein 1 (LRP-1) is involved in BBB disruption after brain ischemia. In this study, we explored whether TXL could downregulate LRP-1 expression and subsequently protect against BBB disruption after stroke using permanent middle cerebral artery occlusion (pMCAO) in mice.

METHODS

The animal model of ischemic stroke was induced by pMCAO in male adult C57BL/6J mice. The mice were orally administered TXL (3.0 g/kg) at 1, 3 and 21 h after pMCAO. Meanwhile, the LRP-1 antagonist receptor associated protein (RAP) was intracerebroventricularly injected at 1 and 21 h after stroke. We measured the following parameters at 6 and 24 h: LRP-1 protein level, BBB leakage, and the expression of tight junction (TJ) proteins including occludin, claudin-5 and zonula occludens-1 (ZO-1).

RESULTS

Our results showed that TXL downregulated LRP-1 level, upregulated these TJ proteins level, and reduced BBB leakage in peri-infarct regions after pMCAO. Further study found that the inhibitor RAP played the same role as did TXL in upregulating these TJ proteins level and reducing BBB leakage after stroke.

CONCLUSION

Our study demonstrates that TXL protects against BBB disruption after stroke via inhibiting the LRP-1 pathway.

Excretory/secretory products of Angiostrongylus cantonensis fifth-stage larvae induce endoplasmic reticulum stress via the Sonic hedgehog pathway in mouse astrocytes

BACKGROUND

Angiostrongylus cantonensis is an important food-borne zoonotic parasite. Humans are non-permissive hosts, and this parasite develops into fifth-stage larvae (L5) in the brain and subarachnoid cavity and then induces eosinophilic meningitis and eosinophilic meningoencephalitis. Excretory/secretory products (ESPs) are valuable targets for the investigation of host-parasite interactions. These products contain a wide range of molecules for penetrating defensive barriers and avoiding the immune response of the host. Endoplasmic reticulum (ER) stress has been found to be associated with a wide range of parasitic infections and inflammation. ER stress can increase cell survival via the activation of downstream signalling. However, the mechanisms of ER stress in A. cantonensis infection have not yet been clarified. This study was designed to investigate the molecular mechanisms of ER stress in astrocytes after treatment with the ESPs of A. cantonensis L5.

RESULTS

The results demonstrated that A. cantonensis infection activated astrocytes in the mouse hippocampus and induced the expression of ER stress-related molecules. Next, the data showed that the expression of ER stress-related molecules and the Ca²⁺ concentration were significantly increased in activated astrocytes after treatment with the ESPs of L5 of A. cantonensis. Ultimately, we found that ESPs induced GRP78 expression via the Sonic hedgehog (Shh) signalling pathway.

CONCLUSIONS

These findings suggest that in astrocytes, the ESPs of A. cantonensis L5 induce ER stress and that the Shh signalling pathway plays an important role in this process.

Involvement of Shh/Gli1 signaling in the permeability of blood-spinal cord barrier and locomotion recovery after spinal cord contusion

Shh/Gli1 signaling plays important roles in development of spinal cord. How it is involved in spinal cord injury (SCI) remains unclear. In this study, we explored the roles of Shh/Gli1 signaling in SCI by using Shh signaling reporter Gli1^lz mice and Gli1 mutant Gli1^lz/lz mice. For detecting the Shh/Gli1 signaling after SCI, X-gal staining and double-immunostaining of Shh/PDGFR-β, Shh/GFAP and LacZ/GFAP was conducted at 3 days post injury (dpi) on Gli1^lz mice. To investigate the effects of Gli1 mutation on pathological changes after SCI, astrocytic proliferation and the content of intra-parenchymal Evans Blue were evaluated at 7dpi in wild-type and Gli1^lz/lz mice. Furthermore, locomotor recovery was assessed by BMS scoring at 1, 3, 5 and 7dpi. The results of X-gal staining and immunohistochemistry showed that Shh/Gli1 signaling was mainly activated in reactive astrocytes after SCI. The 5-bromo-2-deoxyuridine (BrdU) incorporation assay showed that mutation of Gli1 did not affect the proliferation of astrocytes. However, the leakage of Evans Blue was significantly increased in the injured cord of Gli1^lz/lz mice compared to wild-type mice. In addition, locomotor recovery was significantly impaired in the Gli1^lz/lz mice. The findings demonstrated that Shh/Gli1 signaling could be induced in reactive astrocytes by SCI, and plays important role in permeability of blood-spinal cord barrier (BSCB) and locomotor recovery after SCI.

Total Glycosides of Cistanche deserticola Promote Neurological Function Recovery by Inducing Neurovascular Regeneration via Nrf-2/Keap-1 Pathway in MCAO/R Rats

Background

The traditional Chinese medicine Cistanche deserticola has been reported to be valid for cardiovascular and cerebrovascular diseases. However, its active components for the protection of ischemic stroke are not clear. We aimed to explore the active components of C. deserticola against ischemic stroke as well as its potential mechanisms.

Methods

We investigated the brain protective effects of extracts from C. deserticola, total glycosides (TGs), polysaccharides (PSs), and oligosaccharides (OSs) in a rat model of middle cerebral artery occlusion-reperfusion (MCAO/R). 2, 3, 5-Triphenyltetrazolium chloride (TTC) staining was used to assess the cerebral infarction volume, and Evans blue assay was adopted to assess the blood-brain barrier (BBB) permeability. Then, the expressions CD31, α-SMA, PDGFRβ, SYN, PSD95, MAP-2, ZO-1, claudin-5, occludin, Keap-1, and Nrf-2 were analyzed using western blotting or immunofluorescence, and the activities MDA, SOD, CAT, and GSH-Px were analyzed using kits.

Results

TGs treatment remarkably decreased neurological deficit scores and infarction volumes, promoted angiogenesis and neural remodeling, and effectively maintained blood-brain-barrier integrity compared with the model group. Furthermore, TGs significantly decreased MDA levels and increased antioxidant activities (SOD, CAT, and GSH-Px) in brains. Meanwhile, TGs remarkably downregulated Keap-1 expression and facilitated Nrf-2 nuclear translocation. On the contrary, no protective effects were observed for PSs and OSs groups.

Conclusion

TGs are the main active components of C. deserticola against MCAO/R-induced cerebral injury, and protection is mainly via the Nrf-2/Keap-1 pathway.

Astrocyte-Derived Paracrine Signals: Relevance for Neurogenic Niche Regulation and Blood-Brain Barrier Integrity

Astrocytes are essential for proper regulation of the central nervous system (CNS). Importantly, these cells are highly secretory in nature. Indeed they can release hundreds of molecules which play pivotal physiological roles in nervous tissues and whose abnormal regulation has been associated with several CNS disorders. In agreement with these findings, recent studies have provided exciting insights into the key contribution of astrocyte-derived signals in the pleiotropic functions of these cells in brain health and diseases. In the future, deeper analysis of the astrocyte secretome is likely to further increase our current knowledge on the full potential of these cells and their secreted molecules not only as active participants in pathophysiological events, but as pharmacological targets or even as therapeutics for neurological and psychiatric diseases. Herein we will highlight recent findings in our and other laboratories on selected molecules that are actively secreted by astrocytes and contribute in two distinct functions with pathophysiological relevance for the astroglial population: i) regulation of neural stem cells (NSCs) and their progeny within adult neurogenic niches; ii) modulation of the blood–brain barrier (BBB) integrity and function.