Acceleration of NLRP3 inflammasome by chronic cerebral hypoperfusion in Alzheimer's disease model mouse

Autophagy Regulation Attenuates Neuroinflammation and Cognitive Decline in an Alzheimer's Disease Mouse Model with Chronic Cerebral Hypoperfusion

This study investigates the role of autophagy regulation in modulating neuroinflammation and cognitive function in an Alzheimer's disease (AD) mouse model with chronic cerebral hypoperfusion (CCH). Using the APP23/PS1 mice plus CCH model, we examined the impact of autophagy regulation on cognitive function, neuroinflammation, and autophagic activity. Our results demonstrate significant cognitive impairments in AD mice, exacerbated by CCH, but mitigated by treatment with the autophagy inhibitor 3-methyladenine (3-MA). Dysregulation of autophagy-related proteins, accentuated by CCH, underscores the intricate relationship between cerebral blood flow and autophagy dysfunction in AD pathology. While 3-MA restored autophagic balance, rapamycin (RAPA) treatment did not induce significant changes, suggesting alternative therapeutic approaches are necessary. Dysregulated microglial polarization and neuroinflammation in AD+CCH were linked to cognitive decline, with 3-MA attenuating neuroinflammation. Furthermore, alterations in M2 microglial polarization and the levels of inflammatory markers NLRP3 and MCP1 were observed, with 3-MA treatment exhibiting potential anti-inflammatory effects. Our findings shed light on the crosstalk between autophagy and neuroinflammation in AD+CCH and suggest targeting autophagy as a promising strategy for mitigating neuroinflammation and cognitive decline in AD+CCH.

Protective effect of scallop-derived plasmalogen against vascular dysfunction, via the pSTAT3/PIM1/NFATc1 axis, in a novel mouse model of Alzheimer's disease with cerebral hypoperfusion

A strong relationship between Alzheimer's disease (AD) and vascular dysfunction has been the focus of increasing attention in aging societies. In the present study, we examined the long-term effect of scallop-derived plasmalogen (sPlas) on vascular remodeling-related proteins in the brain of an AD with cerebral hypoperfusion (HP) mouse model. We demonstrated, for the first time, that cerebral HP activated the axis of the receptor for advanced glycation endproducts (RAGE)/phosphorylated signal transducer and activator of transcription 3 (pSTAT3)/provirus integration site for Moloney murine leukemia virus 1 (PIM1)/nuclear factor of activated T cells 1 (NFATc1), accounting for such cerebral vascular remodeling. Moreover, we also found that cerebral HP accelerated pSTAT3-mediated astrogliosis and activation of the nucleotide-binding domain and leucine-rich repeat protein 3 (NLRP3) inflammasome, probably leading to cognitive decline. On the other hand, sPlas treatment attenuated the activation of the pSTAT3/PIM1/NFATc1 axis independent of RAGE and significantly suppressed NLRP3 inflammasome activation, demonstrating the beneficial effect on AD.

Protective Effect of Ferulic Acid on Lipopolysaccharide-Induced BV2 Microglia Inflammation via AMPK/mTOR Signaling Pathway

In neurodegenerative diseases, microglial activation and neuroinflammation are essential for the control and progression of neurodegenerative diseases. Mitigating microglium-induced inflammation is one strategy for hindering the progression of neurodegenerative diseases. Ferulic acid (FA) is an effective anti-inflammatory agent, but its potential role and regulation mechanism in neuroinflammatory reactions have not been fully studied. In this study, the neuroinflammation model was established by lipopolysaccharide (LPS), and the inhibitory effect of FA on neuroinflammation of BV2 microglia was studied. The results showed that FA significantly reduced the production and expression of reactive oxygen species (ROS), tumor necrosis factor-α (TNF-α), leukocyte-6 (IL-6) and interleukin-1β (IL-1β). We further studied the mechanism of FA's regulation of LPS-induced BV2 neuroinflammation and found that FA can significantly reduce the expression of mTOR in BV2 microglia induced by LPS, and significantly increase the expression of AMPK, indicating that FA may have an anti-inflammatory effect by activating the AMPK/mTOR signaling pathway to regulate the release of inflammatory mediators (such as NLRP3, caspase-1 p20 and IL-1β). We further added an autophagy inhibitor (3-MA) and an AMPK inhibitor (compound C, CC) for reverse verification. The results showed that FA's inhibitory effects on TNF-α, IL-6 and IL-1β and its regulatory effect on AMPK/mTOR were destroyed by 3-MA and CC, which further indicated that FA's inhibitory effect on neuroinflammation is related to its activation of the AMPK/mTOR autophagy signaling pathway. In a word, our experimental results show that FA can inhibit LPS-induced neuroinflammation of BV2 microglia by activating the AMPK/mTOR signaling pathway, and FA may be a potential drug for treating neuroinflammatory diseases.

What type of cell death occurs in chronic cerebral hypoperfusion? A review focusing on pyroptosis and its potential therapeutic implications

Chronic cerebral hypoperfusion (CCH) is a major global disease with chronic cerebral blood flow reduction. It is also the main cause of cognitive impairment and neurodegenerative diseases. Pyroptosis, a novel form of cell death, is characterized by the rupture of the cell membrane and the release of pro-inflammatory mediators. In recent years, an increasing number of studies have identified the involvement of pyroptosis and its mediated inflammatory response in the pathological process of CCH. Therefore, preventing the activation of pyroptosis following CCH is beneficial to inhibit the inflammatory cascade and reduce brain injury. In this review, we discuss the research progress on the relationship between pyroptosis and CCH, in order to provide a reference for research in related fields.

Microglial autophagy in cerebrovascular diseases

Microglia are considered core regulators for monitoring homeostasis in the brain and primary responders to central nervous system (CNS) injuries. Autophagy affects the innate immune functions of microglia. Recently some evidence suggests that microglial autophagy is closely associated with brain function in both ischemic stroke and hemorrhagic stroke. Herein, we will discuss the interaction between autophagy and other biological processes in microglia under physiological and pathological conditions and highlight the interaction between microglial metabolism and autophagy. In the end, we focus on the effect of microglial autophagy in cerebrovascular diseases.

A non-peptidic MAS1 agonist AVE0991 alleviates hippocampal synaptic degeneration in rats with chronic cerebral hypoperfusion

BACKGROUND

Chronic cerebral hypoperfusion (CCH) is a contributing factor for neurodegenerative diseases. As a recently identified heptapeptide of the brain renin-angiotensin system, angiotensin-(1-7) was revealed to activate its receptor MAS1 and thus ameliorated cognitive impairments in rats with CCH. Since hippocampal synaptic degeneration represents an important pathological basis of cognitive deficits, we hypothesize that activation of MAS1-mediated signaling may alleviate CCH-induced synaptic degeneration in the hippocampus.

METHODS

In this study, we tested this hypothesis and uncovered the underlying mechanisms in a rat model of CCH induced by bilateral common carotid artery ligation surgery. At 1 week after the surgery, rats received a daily intraperitoneal injection of vehicle or a non-peptidic MAS1 agonist AVE0991 for 8 weeks. During this procedure, cerebral blood flow (CBF) was recorded. The levels of MAS1, amyloid-β (Aβ), neuroinflammatory cytokines, glial cell markers and synaptophysin in the hippocampus were assessed at the end of the treatment period.

RESULTS

We showed that AVE0991 significantly alleviated hippocampal synaptic degeneration in rats with CCH. This protection might be achieved by facilitating CBF recovery, reducing hippocampal Aβ levels and suppressing neuroinflammatory responses.

CONCLUSIONS

These findings indicate that MAS1-mediated signaling may represent a novel therapeutic target for CCH-related neurodegenerative diseases.

Oxygen Sensing and Signaling in Alzheimer's Disease: A Breathtaking Story!

Oxygen sensing and homeostasis is indispensable for the maintenance of brain structural and functional integrity. Under low-oxygen tension, the non-diseased brain has the ability to cope with hypoxia by triggering a homeostatic response governed by the highly conserved hypoxia-inducible family (HIF) of transcription factors. With the advent of advanced neuroimaging tools, it is now recognized that cerebral hypoperfusion, and consequently hypoxia, is a consistent feature along the Alzheimer's disease (AD) continuum. Of note, the reduction in cerebral blood flow and tissue oxygenation detected during the prodromal phases of AD, drastically aggravates as disease progresses. Within this scenario a fundamental question arises: How HIF-driven homeostatic brain response to hypoxia "behaves" during the AD continuum? In this sense, the present review is aimed to critically discuss and summarize the current knowledge regarding the involvement of hypoxia and HIF signaling in the onset and progression of AD pathology. Importantly, the promises and challenges of non-pharmacological and pharmacological strategies aimed to target hypoxia will be discussed as a new "hope" to prevent and/or postpone the neurodegenerative events that occur in the AD brain.

The Role of the Effects of Autophagy on NLRP3 Inflammasome in Inflammatory Nervous System Diseases

Autophagy is a stable self-sustaining process in eukaryotic cells. In this process, pathogens, abnormal proteins, and organelles are encapsulated by a bilayer membrane to form autophagosomes, which are then transferred to lysosomes for degradation. Autophagy is involved in many physiological and pathological processes. Nucleotide-binding oligomerization domain-like receptor protein 3 (NLRP3) inflammasome, containing NLRP3, apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC) and pro-caspase-1, can activate caspase-1 to induce pyroptosis and lead to the maturation and secretion of interleukin-1 β (IL-1 β) and IL-18. NLRP3 inflammasome is related to many diseases. In recent years, autophagy has been reported to play a vital role by regulating the NLRP3 inflammasome in inflammatory nervous system diseases. However, the related mechanisms are not completely clarified. In this review, we sum up recent research about the role of the effects of autophagy on NLRP3 inflammasome in Alzheimer’s disease, chronic cerebral hypoperfusion, Parkinson’s disease, depression, cerebral ischemia/reperfusion injury, early brain injury after subarachnoid hemorrhage, and experimental autoimmune encephalomyelitis and analyzed the related mechanism to provide theoretical reference for the future research of inflammatory neurological diseases.

A New Serum Biomarker Set to Detect Mild Cognitive Impairment and Alzheimer's Disease by Peptidome Technology

Background:

Because dementia is an emerging problem in the world, biochemical markers of cerebrospinal fluid (CSF) and radio-isotopic analyses are helpful for diagnosing Alzheimer’s disease (AD). Although blood sample is more feasible and plausible than CSF or radiological biomarkers for screening potential AD, measurements of serum amyloid- β (Aβ), plasma tau, and serum antibodies for Aβ_1 - 42 are not yet well established.

Objective:

We aimed to identify a new serum biomarker to detect mild cognitive impairment (MCI) and AD in comparison to cognitively healthy control by a new peptidome technology.

Methods:

With only 1.5μl of serum, we examined a new target plate “BLOTCHIP^®” plus a matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF/MS) to discriminate control (n = 100), MCI (n = 60), and AD (n = 99). In some subjects, cognitive Mini-Mental State Examination (MMSE) were compared to positron emission tomography (PET) with Pittsburgh compound B (PiB) and the serum probability of dementia (SPD). The mother proteins of candidate serum peptides were examined in autopsied AD brains.

Results:

Apart from Aβ or tau, the present study discovered a new diagnostic 4-peptides-set biomarker for discriminating control, MCI, and AD with 87% of sensitivity and 65% of specificity between control and AD (^***p < 0.001). MMSE score was well correlated to brain Aβ deposition and to SPD of AD. The mother proteins of the four peptides were upregulated for coagulation, complement, and plasticity (three proteins), and was downregulated for anti-inflammation (one protein) in AD brains.

Conclusion:

The present serum biomarker set provides a new, rapid, non-invasive, highly quantitative and low-cost clinical application for dementia screening, and also suggests an alternative pathomechanism of AD for neuroinflammation and neurovascular unit damage.

Impaired Cognitive Flexibility Induced by Chronic Cerebral Hypoperfusion in the 5XFAD Transgenic Mouse Model of Mixed Dementia

Cerebrovascular lesions are widely prevalent in patients with Alzheimer’s disease (AD), but their relationship to the pathophysiology of AD remains poorly understood. An improved understanding of the interaction of cerebrovascular damage with AD is crucial for the development of therapeutic approaches. Herein, we investigated the effects of chronic cerebral hypoperfusion (CCH) in a 5XFAD transgenic (Tg) mouse model of AD. We established CCH conditions in both Tg and non-Tg mice by inducing unilateral common carotid artery occlusion (UCCAO). Cognitive performance in mice was evaluated, and their brain tissue was examined for amyloid-beta (Aβ) pathology to elucidate possible mechanisms. We found that UCCAO-operated Tg mice showed impaired cognitive flexibility in the reversal phase of the hidden-platform water maze task compared to sham-operated Tg mice. Interestingly, UCCAO-operated Tg mice used fewer spatial cognitive strategies than sham-operated Tg mice during reversal learning. These cognitive deficits were accompanied by increased Aβ plaque burden and Aβ42 levels in the hippocampus and prefrontal cortex, 2 regions that play essential roles in the regulation of cognitive flexibility. Furthermore, changes in cognitive flexibility are strongly correlated with the expression levels of enzymes related to Aβ clearance, such as neprilysin and insulin-degrading enzymes. These findings suggest that, in 5XFAD mice, impaired cognitive flexibility is related to CCH, and that Aβ clearance might be involved in this process.

Vascular Hypothesis of Alzheimer Disease: Topical Review of Mouse Models

[Figure: see text].

Caspase-1/IL-1β represses membrane transport of GluA1 by inhibiting the interaction between Stargazin and GluA1 in Alzheimer's disease

Background

Alzheimer's disease is a neurodegenerative disease. Previous study has reported that caspase-1/IL-1β is closely associated with Alzheimer's disease. However, the biological role of caspase-1/IL-1β in Alzheimer's disease has not been fully elucidated. This study aimed to explore the mechanism of action of caspase-1/IL-1β in Alzheimer's disease.

Methods

Mouse hippocampal neurones were treated with Aβ_1-42 to induce Alzheimer's disease cell model. APP/PS1 mice and Aβ_1-42-induced hippocampal neurones were treated with AC-YVAD-CMK (caspase-1 inhibitor). Spatial learning and memory ability of mice were detected by morris water maze. Flow cytometry, TUNEL staining, Thioflavin S staining and immunohistochemistry were performed to examine apoptosis and senile plaque deposition. Enzyme linked immunosorbent assay and western blot were performed to assess the levels of protein or cytokines. Co-Immunoprecipitation was performed to verify the interaction between Stargazin and GluA1.

Results

AC-YVAD-CMK treatment improved spatial learning and memory ability and reduced senile plaque deposition of APP/PS1 mice. Moreover, AC-YVAD-CMK promoted membrane transport of GluA1 in APP/PS1 mice. In vitro, Aβ_1-42-induced hippocampal neurones exhibited an increase in apoptosis and a decrease in the membrane transport of GluA1, which was abolished by AC-YVAD-CMK treatment. In addition, Stargazin interacted with GluA1, which was repressed by caspase-1. Caspase-1/IL-1β inhibited membrane transport of GluA1 by inhibiting the interaction between Stargazin and GluA1.

Conclusions

Our data demonstrate that caspase-1/IL-1β represses membrane transport of GluA1 by inhibiting the interaction between Stargazin in Alzheimer's disease. Thus, caspase-1/IL-1β may be a target for Alzheimer's disease treatment.

Acupuncture attenuates cognitive deficits through α7nAChR mediated anti-inflammatory pathway in chronic cerebral hypoperfusion rats

AIMS

Chronic cerebral hypoperfusion (CCH) elicits inflammatory response, which contributes to the pathology of cognitive impairment. Several studies demonstrate that the alpha-7 nicotinic acetylcholine receptor (α7nAChR) can be a key component to modulate the inflammatory responses. We have reported previously that acupuncture attenuated cognitive deficits induced by CCH. In present study, whether effect of acupuncture was related to α7nAChR mediated anti-inflammatory pathway in CCH rats was further explored.

MAIN METHODS

Acupuncture was performed in CCH rats induced by bilateral common carotid arteries occlusion. Neuronal injury, the activation of microglia, the release of inflammatory cytokines, the expression of α7nAChR, and the activation of JAK2/STAT3 signaling pathways were detected. Cognitive function and central inflammation were evaluated after the intraperitoneal injection of an α7nAChR agonist PNU282987, or intracerebroventricular injection of an α7nAChR antagonist α-bungarotoxin (α-BGT).

KEY FINDINGS

We found that there were neuronal damage and inflammation, accompanied with the decreased expressions of α7nAChR in the hippocampus under CCH condition. Acupuncture inhibited neuronal damage, activation of microglia, and inflammatory cytokines. The expressions of α7nAChR, together with its downstream JAK2/STAT3 pathways were up regulated by acupuncture. PNU282987 mimicked the anti-inflammatory and neuroprotective effects as well as the cognitive improvements of acupuncture. Meanwhile, the benefit effects of acupuncture above were blocked by α-BGT.

SIGNIFICANCE

It was demonstrated that acupuncture promoted cognitive function and afforded neuroprotective effects against inflammation via activation of α7nAChR and its downstream JAK2-STAT3 pathway in CCH rats. It provides a new insight for acupuncture as an anti-inflammatory intervention for cognitive impairment.

Lychee seed polyphenol inhibits Aβ-induced activation of NLRP3 inflammasome via the LRP1/AMPK mediated autophagy induction

Emerging evidence indicates that the enhancement of microglial autophagy inhibits the NLRP3 inflammasome mediated neuroinflammation in Alzheimer's disease (AD). Meanwhile, low density lipoprotein receptor-related protein 1 (LRP1) highly expressed in microglia is able to negatively regulate neuroinflammation and positively regulate autophagy. In addition, we have previously reported that an active lychee seed fraction enriching polyphenol (LSP) exhibits anti-neuroinflammation in Aβ-induced BV-2 cells. However, its molecular mechanism of action is still unclear. In this study, we aim to investigate whether LSP inhibits the NLRP3 inflammasome mediated neuroinflammation and clarify its molecular mechanism in Aβ-induced BV-2 cells and APP/PS1 mice. The results showed that LSP dose- and time-dependently activated autophagy by increasing the expression of Beclin 1 and LC3II in BV-2 cells, which was regulated by the upregulation of LRP1 and its mediated AMPK signaling pathway. In addition, both the Western blotting and fluorescence microscopic results demonstrated that LSP could significantly suppress the activation of NLRP3 inflammasome by inhibiting the expression of NLRP3, ASC, the cleavage of caspase-1, and the release of IL-1β in Aβ(1-42)-induced BV-2 cells. In addition, the siRNA LRP1 successfully abolished the effect of LSP on the activation of AMPK and its mediated autophagy, as well as the inhibition of NLRP3 inflammasome. Furthermore, LSP rescued PC-12 cells which were induced by the conditioned medium from Aβ(1-42)-treated BV-2 cells. Moreover, LSP improved the cognitive function and inhibited the NLRP3 inflammasome in APP/PS1 mice. Taken together, LSP inhibited the NLRP3 inflammasome-mediated neuroinflammation in the in vitro and in vivo models of AD, which was closely associated with the LRP1/AMPK-mediated autophagy. Thus, the findings from this study further provide evidences for LSP serving as a potential drug for the treatment of AD in the future.

Key Mechanisms and Potential Targets of the NLRP3 Inflammasome in Neurodegenerative Diseases

Neurodegenerative diseases are neuronal disorders characterized by the loss of a large number of neurons in the human brain. Innate immunity-mediated neuroinflammation actively contributes to the onset and progression of neurodegenerative diseases. Inflammasomes are involved in the progression of the innate immune response and are responsible for the maturation of caspase-1 and inflammatory cytokines during neuroinflammation. The nucleotide-binding oligomerization domain leucine-rich repeat and pyrin domain-containing protein 3 (NLRP3) inflammasome, which is one of the most intensively investigated inflammasomes, has been reported to play a key role in neurodegenerative diseases. Here, we reviewed the mechanisms, role, and latest developments regarding the NLRP3 inflammasome with respect to three neurodegenerative diseases: Alzheimer’s disease (AD), Parkinson’s disease (PD), and amyotrophic lateral sclerosis (ALS). Patient and animal model studies have found that abnormal protein aggregation of Aβ, synuclein, or copper–zinc superoxide dismutase-1 (SOD1), which are the main proteins expressed in the three diseases, respectively, can activate microglial cells, induce increased interleukin-1β (IL-1β) release, and activate the NLRP3 pathway, leading to neurodegeneration. In contrast, a deficiency of the components of the NLRP3 pathway may inhibit Aβ, synuclein, or SOD1-induced microglial activation. These studies indicate a positive correlation between NLRP3 levels and abnormal protein aggregation. However, in the case of ALS, not only microglia but also astrocytes express increased NLRP3 levels and contribute to activation of the NLRP3 pathway. In addition, in this review article, we also focus on the therapeutic implications of targeting novel inhibitors of the NLRP3 inflammasome or of novel drugs that mediate the NLRP3 pathway, which could play a role via NLRP3 in the treatment of neurodegenerative diseases.

Role of HMGB1 in an Animal Model of Vascular Cognitive Impairment Induced by Chronic Cerebral Hypoperfusion

The pathophysiology of vascular cognitive impairment (VCI) is associated with chronic cerebral hypoperfusion (CCH). Increased high-mobility group box protein 1 (HMGB1), a nonhistone protein involved in injury and inflammation, has been established in the acute phase of CCH. However, the role of HMGB1 in the chronic phase of CCH remains unclear. We developed a novel animal model of CCH with a modified bilateral common carotid artery occlusion (BCCAO) in C57BL/6 mice. Cerebral blood flow (CBF) reduction, the expression of HMGB1 and its proinflammatory cytokines (tumor necrosis factor-alpha [TNF-α], interleukin [IL]-1β, and IL-6), and brain pathology were assessed. Furthermore, we evaluated the effect of HMGB1 suppression through bilateral intrahippocampus injection with the CRISPR/Cas9 knockout plasmid. Three months after CCH induction, CBF decreased to 30–50% with significant cognitive decline in BCCAO mice. The 7T-aMRI showed hippocampal atrophy, but amyloid positron imaging tomography showed nonsignificant amyloid-beta accumulation. Increased levels of HMGB1, TNF-α, IL-1β, and IL-6 were observed 3 months after BCCAO. HMGB1 suppression with CRISPR/Cas9 knockout plasmid restored TNF-α, IL-1β, and IL-6 and attenuated hippocampal atrophy and cognitive decline. We believe that HMGB1 plays a pivotal role in CCH-induced VCI pathophysiology and can be a potential therapeutic target of VCI.

Alzheimer's Disease: The Link Between Amyloid-β and Neurovascular Dysfunction

While prevailing evidence supports that the amyloid cascade hypothesis is a key component of Alzheimer's disease (AD) pathology, many recent studies indicate that the vascular system is also a major contributor to disease progression. Vascular dysfunction and reduced cerebral blood flow (CBF) occur prior to the accumulation and aggregation of amyloid-β (Aβ) plaques and hyperphosphorylated tau tangles. Although research has predominantly focused on the cellular processes involved with Aβ-mediated neurodegeneration, effects of Aβ on CBF and neurovascular coupling are becoming more evident. This review will describe AD vascular disturbances as they relate to Aβ, including chronic cerebral hypoperfusion, hypertension, altered neurovascular coupling, and deterioration of the blood-brain barrier. In addition, we will describe recent findings about the relationship between these vascular defects and Aβ accumulation with emphasis on in vivo studies utilizing rodent AD models.

URB597 protects against NLRP3 inflammasome activation by inhibiting autophagy dysfunction in a rat model of chronic cerebral hypoperfusion

Background

Previous studies reported that URB597 (URB) had therapeutic potential for treating chronic cerebral hypoperfusion (CCH)-induced neuroinflammation and autophagy dysfunction. However, the interaction mechanisms underlying the CCH-induced abnormal excessive autophagy and neuroinflammation remain unknown. In this study, we investigated the roles of impaired autophagy in nucleotide-binding oligomerization domain-like receptor family pyrin domain-containing (NLRP) 3 inflammasome activation in the rat hippocampus and the underlying mechanisms under the condition of induced CCH as well as the effect of URB treatment.

Methods

The CCH rat model was established by bilateral common carotid artery occlusion (BCCAo), and rats were randomly divided into 11 groups as follows: (1) sham-operated, (2) BCCAo; (3) BCCAo+autophagy inhibitor 3-methyladenine (3-MA), (4) BCCAo+lysosome inhibitor chloroquine (CQ), (5) BCCAo+microglial activation inhibitor minocycline, (6) BCCAo+ROS scavenger N-acetylcysteine (NAC), (7) BCCAo+URB, (8) BCCAo+URB+3-MA, (9) BCCAo+URB+CQ, (10) BCCAo+URB+minocycline, (11) BCCAo+URB+NAC. The cell localizations of LC3, p62, LAMP1, TOM20 and NLRP3 were assessed by immunofluorescence staining. The levels of autophagy-related proteins (LC3, p62, LAMP1, BNIP3 and parkin), NLRP3 inflammasome-related proteins (NLRP3, CASP1 and IL-1β), microglial marker (OX-42) and proinflammatory cytokines (iNOS and COX-2) were evaluated by western blotting, and proinflammatory cytokines (IL-1β and TNF-a) were determined by ELISA. Reactive oxygen species (ROS) were assessed by dihydroethidium staining. The mitochondrial ultrastructural changes were examined by electron microscopy.

Results

CCH induced microglial overactivation and ROS accumulation, promoting the activation of the NLRP3 inflammasome and the release of IL-1β. Blocked autophagy and mitophagy flux enhanced the activation of the NLRP3-CASP1 inflammasome pathway. However, URB alleviated impaired autophagy and mitophagy by decreasing mitochondrial ROS and microglial overactivation as well as restoring lysosomal function, which would further inhibit the activation of the NLRP3-CASP1 inflammasome pathway.

Conclusion

These findings extended previous studies indicating the function of URB in the mitigation of chronic ischemic injury of the brain.

Mumefural Ameliorates Cognitive Impairment in Chronic Cerebral Hypoperfusion via Regulating the Septohippocampal Cholinergic System and Neuroinflammation

Chronic cerebral hypoperfusion (CCH) causes cognitive impairment and neurogenic inflammation by reducing blood flow. We previously showed that Fructus mume (F. mume) improves cognitive impairment and inhibits neuroinflammation in a CCH rat model. One of the components of F. mume, Mumefural (MF), is known to improve blood flow and inhibit platelet aggregation. Whether MF affects cerebral and cognitive function remains unclear. We investigated the effects of MF on cognitive impairment and neurological function-related protein expression in the rat CCH model, established by bilateral common carotid arterial occlusion (BCCAo). Three weeks after BCCAo, MF (20, 40, or 80 mg/kg) was orally administrated once a day for 42 days. Using Morris water maze assessment, MF treatment significantly improved cognitive impairment. MF treatment also inhibited cholinergic system dysfunction, attenuated choline acetyltransferase-positive cholinergic neuron loss, and regulated cholinergic system-related protein expressions in the basal forebrain and hippocampus. MF also inhibited myelin basic protein degradation and increased the hippocampal expression of synaptic markers and cognition-related proteins. Moreover, MF reduced neuroinflammation, inhibited gliosis, and attenuated the activation of P2X7 receptor, TLR4/MyD88, NLRP3, and NF-κB. This study indicates that MF ameliorates cognitive impairment in BCCAo rats by enhancing neurological function and inhibiting neuroinflammation.

Cerebrovascular inflammation: A critical trigger for neurovascular injury?

The cerebrovascular system is not only inert bystandard that support the metabolic demands of the brain but also elicit the barrier functions against risk factors mediated neurovascular injury. The onsets of cerebrovascular inflammation are considered as stimuli that can provoke the host defense system and trigger the development of neurological disorders. Homeostasis of the brain function is regulated by the movement of endothelial, glial, and neuronal cells within the neurovascular unit (NVU), which acts as a "platform" for the coordinated action of anti- and pro-inflammatory mechanisms. The cerebrovascular system plays an integral role in the inflammatory response by either producing or expressing a variety of cytokines, adhesion molecules, metalloproteinases, and serine proteases. Excessive inflammatory cytokine production can further be affecting the blood-brain barrier (BBB) integrity and lead to brain tissue damage. In this review, we summarize the more recent evidence highlighting the importance of cerebrovascular injury in terms of risk prediction, and the mechanisms mediating the upregulation of inflammatory mediators in cerebrovascular dysfunction and neurodegeneration.

Tripchlorolide May Improve Spatial Cognition Dysfunction and Synaptic Plasticity after Chronic Cerebral Hypoperfusion

Chronic cerebral hypoperfusion (CCH) is a common pathophysiological mechanism that underlies cognitive decline and degenerative processes in dementia and other neurodegenerative diseases. Low cerebral blood flow (CBF) during CCH leads to disturbances in the homeostasis of hemodynamics and energy metabolism, which in turn results in oxidative stress, astroglia overactivation, and synaptic protein downregulation. These events contribute to synaptic plasticity and cognitive dysfunction after CCH. Tripchlorolide (TRC) is an herbal compound with potent neuroprotective effects. The potential of TRC to improve CCH-induced cognitive impairment has not yet been determined. In the current study, we employed behavioral techniques, electrophysiology, Western blotting, immunofluorescence, and Golgi staining to investigate the effect of TRC on spatial learning and memory impairment and on synaptic plasticity changes in rats after CCH. Our findings showed that TRC could rescue CCH-induced spatial learning and memory dysfunction and improve long-term potentiation (LTP) disorders. We also found that TRC could prevent CCH-induced reductions in N-methyl-D-aspartic acid receptor 2B, synapsin I, and postsynaptic density protein 95 levels. Moreover, TRC upregulated cAMP-response element binding protein, which is an important transcription factor for synaptic proteins. TRC also prevented the reduction in dendritic spine density that is caused by CCH. However, sham rats treated with TRC did not show any improvement in cognition. Because CCH causes disturbances in brain energy homeostasis, TRC therapy may resolve this instability by correcting a variety of cognitive-related signaling pathways. However, for the normal brain, TRC treatment led to neither disturbance nor improvement in neural plasticity. Additionally, this treatment neither impaired nor further improved cognition. In conclusion, we found that TRC can improve spatial learning and memory, enhance synaptic plasticity, upregulate the expression of some synaptic proteins, and increase the density of dendritic spines. Our findings suggest that TRC may be beneficial in the treatment of cognitive impairment induced by CCH.