HDAC inhibitor protects chronic cerebral hypoperfusion and oxygen-glucose deprivation injuries via H3K14 and H4K5 acetylation-mediated BDNF expression

Elucidating the mechanisms of Buyang Huanwu Decoction in treating chronic cerebral ischemia: A combined approach using network pharmacology, molecular docking, and in vivo validation

OBJECTIVE

This study aimed to explore the potential mechanisms of Buyang Huanwu Decoction (BHD) in regulating the AKT/TP53 pathway and reducing inflammatory responses for the treatment of chronic cerebral ischemia (CCI) using UHPLC-QE-MS combined with network pharmacology, molecular docking techniques, and animal experiment validation.

METHODS

Targets of seven herbal components in BHD, such as Astragalus membranaceus, Paeoniae Rubra Radix, and Ligusticum chuanxiong, were identified through TCMSP and HERB databases. CCI-related targets were obtained from DisGeNET and Genecards, with an intersection analysis conducted to determine shared targets between the disease and the herbal components. Functional enrichment analysis of these intersecting targets was performed. Networks of gene ontology and pathway associations with these targets were constructed and visualized. A pharmacological network involving intersecting genes and active components was delineated. A protein-protein interaction network was established for these intersecting targets and visualized using Cytoscape 3.9.1. The top five genes from the PPI network and their corresponding active components underwent molecular docking. Finally, the 2-vessel occlusion (2-VO) induced CCI rat model was treated with BHD, and the network pharmacology findings were validated using Western blot, RT-PCR, behavioral tests, laser speckle imaging, ELISA, HE staining, Nissl staining, LFB staining, and immunohistochemistry and immunofluorescence.

RESULTS

After filtration and deduplication, 150 intersecting genes were obtained, with the top five active components by Degree value identified as Quercetin, Beta-Sitosterol, Oleic Acid, Kaempferol, and Succinic Acid. KEGG pathway enrichment analysis linked key target genes significantly with Lipid and atherosclerosis, AGE-RAGE signaling pathway, IL-17 signaling pathway, and TNF signaling pathway. The PPI network highlighted ALB, IL-6, AKT1, TP53, and IL-1β as key protein targets. Molecular docking results showed the strongest binding affinity between ALB and Beta-Sitosterol. Behavioral tests using the Morris water maze indicated that both medium and high doses of BHD could enhance spatial memory in 2-VO model rats, with high-dose BHD being more effective. Laser speckle results showed that BHD at medium and high doses could facilitate CBF recovery in CCI rats, demonstrating a dose-response relationship. HE staining indicated that all doses of BHD could reduce neuronal damage in the cortex and hippocampal CA1 region to varying extents, with the highest dose being the most efficacious. Nissl staining showed that nimodipine and medium and high doses of BHD could alleviate Nissl body damage. LFB staining indicated that nimodipine and medium and high doses of BHD could reduce the pathological damage to fiber bundles and myelin sheaths in the internal capsule and corpus callosum of CCI rats. ELISA results showed that nimodipine and BHD at medium and high doses could decrease the levels of TNF-α, IL-6, IL-17, and IL-1β in the serum of CCI rats (p < 0.05). Immunohistochemistry and immunofluorescence demonstrated that BHD could activate the AKT signaling pathway and inhibit TP53 in treating CCI. Western blot and RT-PCR results indicated that nimodipine and all doses of BHD could upregulate Akt1 expression and downregulate Alb, Tp53, Il-1β, and Il-6 expression in the hippocampus of CCI rats to varying degrees (p < 0.05).

CONCLUSION

BHD exerts therapeutic effects in the treatment of CCI by regulating targets, such as AKT1, ALB, TP53, IL-1β, and IL-6, and reducing inflammatory responses.

Vascular dementia: From pathobiology to emerging perspectives

Vascular dementia (VaD) is the second most common type of dementia. VaD is synonymous with ageing, and its symptoms place a significant burden on the health and wellbeing of older people. Despite the identification of a substantial number of risk factors for VaD, the pathological mechanisms underpinning this disease remain to be fully elucidated. Consequently, a biogerontological imperative exists to highlight the modifiable lifestyle factors which can mitigate against the risk of developing VaD. This review will critically examine some of the factors which have been revealed to modulate VaD risk. The survey commences by providing an overview of the putative mechanisms which are associated with the pathobiology of VaD. Next, the factors which influence the risk of developing VaD are examined. Finally, emerging treatment avenues including epigenetics, the gut microbiome, and pro-longevity pharmaceuticals are discussed. By drawing this key evidence together, it is our hope that it can be used to inform future experimental investigations in this field.

Nasal Administration of bFGF-Loaded Nanoliposomes Attenuates Neuronal Injury and Cognitive Deficits in Mice with Vascular Dementia Induced by Repeated Cerebral Ischemia‒Reperfusion

Introduction

Basic fibroblast growth factor (bFGF) shows great potential for preventing vascular dementia (VD). However, the blood‒brain barrier (BBB) and low bioavailability of bFGF in vivo limit its application. The present study investigated how nasal administration of bFGF-loaded nanoliposomes (bFGF-lips) affects the impaired learning and cognitive function of VD mice and the underlying mechanism involved.

Methods

A mouse model of VD was established through repeated cerebral ischemia‒reperfusion. A Morris water maze (MWM) and novel object recognition (NOR) tests were performed to assess the learning and cognitive function of the mice. Hematoxylin and eosin (HE) staining, Nissl staining and TUNEL staining were used to evaluate histopathological changes in mice in each group. ELISA and Western blot analysis were used to investigate the molecular mechanism by which bFGF-lips improve VD incidence.

Results

Behavioral and histopathological analyses showed that cognitive function was significantly improved in the bFGF-lips group compared to the VD and bFGF groups; in addition, abnormalities and the apoptosis indices of hippocampal neurons were significantly decreased. ELISA and Western blot analysis revealed that bFGF-lips nasal administration significantly increased the concentrations of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), bFGF, B-cell lymphoma 2 (Bcl-2), phosphorylated protein kinase B (PAKT), nuclear factor erythroid 2-related factor 2 (Nrf2), NAD(P)H quinone oxidoreductase 1 (NQO1) and haem oxygenase-1 (HO-1) in the hippocampus of bFGF-lips mice compared with the VD and bFGF groups. Furthermore, the concentrations of malondialdehyde (MDA), caspase-3 and B-cell lymphoma 2-associated X (Bax) were clearly lower in the bFGF-lips group than in the VD and bFGF groups.

Conclusion

This study confirmed that the nasal administration of bFGF-lips significantly increased bFGF concentrations in the hippocampi of VD mice. bFGF-lips treatment reduced repeated I/R-induced neuronal apoptosis by regulating apoptosis-related protein concentrations and activating the phosphatidylinositol-3-kinase (PI3K)/(AKT)/Nrf2 signaling pathway to inhibit oxidative stress.

Identification of differentially expressed exosome proteins in serum as potential biomarkers for cognitive impairments in cerebral small vessel disease

BACKGROUND

Cognitive impairment arising from cerebral small vessel disease (CSVD) represents a critical subtype of vascular cognitive impairments (VCI) and is the primary cause of vascular dementia. However, identifying reliable clinical and laboratory indicators for this disease remain elusive. We hypothesize that plasma exosome proteins hold the potential to serve as biomarkers for the onset of cognitive dysfunction associated with cerebrovascular diseases.

METHODS

We employed TMT-based proteomics to discern variations in serum exosome proteomes between individuals with cognitive impairments due to CSVD and healthy volunteers.

RESULTS

Each group comprised 18 subjects, and through differential expression analysis, we identified 22 down-regulated and 8 up-regulated proteins between the two groups. Our research revealed 30 differentially expressed plasma exosome proteins, including histone, proteasome, clusterin and coagulation factor XIII, in individuals with cognitive impairments caused by CSVD.

CONCLUSION

The 30 differentially expressed plasma exosome proteins identified in our study are promising as biomarkers for diagnosing cognitive impairments resulting from CSVD. These findings may help us better understand the underlying pathological mechanisms involved in the diseases.

Tangeretin confers neuroprotection, cognitive and memory enhancement in global cerebral ischemia in rats

Global cerebral ischemia is commonly associated with neurological deficits, including cognitive and memory impairments. The present study aims to investigate the neuroprotective, cognitive, and memory enhancement effects of Tangeretin, a flavonoid against global cerebral ischemia in rats. Bilateral common carotid artery occlusion (BCCAO) and reperfusion injury method was used to induce global cerebral ischemia in rats. Motor, cognitive, and memory functions were evaluated using rotarod, grip strength, Y-maze, and Morris water maze. Further, acetylcholine esterase (AchE) enzyme activity, acetylcholine (Ach), oxidative stress markers (ROS, SOD, MDA, and CAT), inflammation (IL-6 and TNF-α), and apoptotic markers (cytochrome C, caspase 9, and caspase 3) in BCCAO rats were measured following Tangeretin (5,10, and 20 mg/kg, oral) treatment. Our findings show that Tangeretin treatment significantly improved cognition and memory by enhancing Ach levels through the amelioration of AchE enzyme activity in BCCAO rats. Moreover, Tangeretin exhibited neuroprotective effects through the mitigation of oxidative stress, inflammation, and apoptosis in the BCCAO rats. In summary, the current findings suggested that Tangeretin exhibited neuroprotection, cognitive and memory enhancement against global cerebral ischemia.

Assessment of Four Serum Biochemical Markers in Elderly Patients with Vascular Dementia after Cerebral Infarction and Their Response to Donepezil and Idebenone

Objective  Our study aimed to explore four serum levels of biochemical markers, including brain-derived neurotrophic factor (BDNF), homocysteine (Hcy), nitric oxide (NO), and γ-interferon (IFN-γ), in elderly patients with vascular dementia (VD) after the cerebral infarction and to elucidate possible connections between them. Method  The elderly patients with VD after cerebral infarction admitted in our hospital, and the elderly persons for physical examination from November 2020 to December 2021 were included in this study. The serum levels of BDNF, Hcy, NO, and IFN-γ were compared between the study group and the control group. Results  In the study group, the serum levels of Hcy and IFN-γ were significantly higher than that in the control group, whereas significantly lower serum levels of BDNF and NO were found in the study group compared with the control group. After receiving the intervention of donepezil and/or idebenone, the serum levels of Hcy and IFN-γ in group B were significantly lower than that in group A, while the serum levels of BDNF and NO in group B were significantly higher than that in Group A. Conclusion  The results of our study showed abnormally expressed serum levels of Hcy, IFN-γ, BDNF, and NO in elderly patients with VD after cerebral infarction which might strongly reflect the severity of VD. Moreover, after intervention of donepezil alone or combined with idebenone, the changes of serum levels of Hcy, IFN-γ, BDNF, and NO may reflect the curative effect of the disease.

Neuronal Responses to Ischemia: Scoping Review of Insights from Human-Derived In Vitro Models

Translation of neuroprotective treatment effects from experimental animal models to patients with cerebral ischemia has been challenging. Since pathophysiological processes may vary across species, an experimental model to clarify human-specific neuronal pathomechanisms may help. We conducted a scoping review of the literature on human neuronal in vitro models that have been used to study neuronal responses to ischemia or hypoxia, the parts of the pathophysiological cascade that have been investigated in those models, and evidence on effects of interventions. We included 147 studies on four different human neuronal models. The majority of the studies (132/147) was conducted in SH-SY5Y cells, which is a cancerous cell line derived from a single neuroblastoma patient. Of these, 119/132 used undifferentiated SH-SY5Y cells, that lack many neuronal characteristics. Two studies used healthy human induced pluripotent stem cell derived neuronal networks. Most studies used microscopic measures and established hypoxia induced cell death, oxidative stress, or inflammation. Only one study investigated the effect of hypoxia on neuronal network functionality using micro-electrode arrays. Treatment targets included oxidative stress, inflammation, cell death, and neuronal network stimulation. We discuss (dis)advantages of the various model systems and propose future perspectives for research into human neuronal responses to ischemia or hypoxia.

Role of SH3GLB1 in the regulation of CD133 expression in GBM cells

BACKGROUND

Glioblastoma (GBM), a malignant brain tumor, has poor survival outcomes due to recurrence or drug resistance. We found that SH3GLB1 is a crucial factor for cells to evade temozolomide (TMZ) cytotoxicity through autophagy-mediated oxidative phosphorylation, which is associated with CD133 levels. Therefore, we propose that SH3GLB1 participate in the impact on tumor-initiating cells (TICs).

METHODS

The parental, the derived resistant cell lines and their CD133⁺ cells were used, and the levels of the proteins were compared by western blotting. Then RNA interference was applied to observe the effects of the target protein on TIC-related features. Finally, in vitro transcription assays were used to validate the association between SH3GLB1 and CD133.

RESULTS

The CD133⁺ cells from resistant cells with enhanced SH3GLB1 levels more easily survived cytotoxic treatment than those from the parental cells. Inhibition of SH3GLB1 attenuated frequency and size of spheroid formation, and the levels of CD133 and histone 4 lysine 5 (H4K5) acetylation can be simultaneously regulated by SH3GLB1 modification. The H4K5 acetylation of the CD133 promoter was later suggested to be the mediating mechanism of SH3GLB1.

CONCLUSIONS

These data indicate that SH3GLB1 can regulate CD133 expression, suggesting that the protein plays a crucial role in TICs. Our findings on the effects of SH3GLB1 on the cells will help explain tumor resistance formation.

Endothelial Dysfunction in Neurodegenerative Diseases

The cerebral vascular system stringently regulates cerebral blood flow (CBF). The components of the blood-brain barrier (BBB) protect the brain from pathogenic infections and harmful substances, efflux waste, and exchange substances; however, diseases develop in cases of blood vessel injuries and BBB dysregulation. Vascular pathology is concurrent with the mechanisms underlying aging, Alzheimer's disease (AD), and vascular dementia (VaD), which suggests its involvement in these mechanisms. Therefore, in the present study, we reviewed the role of vascular dysfunction in aging and neurodegenerative diseases, particularly AD and VaD. During the development of the aforementioned diseases, changes occur in the cerebral blood vessel morphology and local cells, which, in turn, alter CBF, fluid dynamics, and vascular integrity. Chronic vascular inflammation and blood vessel dysregulation further exacerbate vascular dysfunction. Multitudinous pathogenic processes affect the cerebrovascular system, whose dysfunction causes cognitive impairment. Knowledge regarding the pathophysiology of vascular dysfunction in neurodegenerative diseases and the underlying molecular mechanisms may lead to the discovery of clinically relevant vascular biomarkers, which may facilitate vascular imaging for disease prevention and treatment.

Triptolide protects against white matter injury induced by chronic cerebral hypoperfusion in mice

White matter injury is the major pathological alteration of subcortical ischemic vascular dementia (SIVD) caused by chronic cerebral hypoperfusion. It is characterized by progressive demyelination, apoptosis of oligodendrocytes and microglial activation, which leads to impairment of cognitive function. Triptolide exhibits a variety of pharmacological activities including anti-inflammation, immunosuppression and antitumor, etc. In this study, we investigated the effects of triptolide on white matter injury and cognitive impairments in mice with chronic cerebral hypoperfusion induced by the right unilateral common carotid artery occlusion (rUCCAO). We showed that triptolide administration alleviated the demyelination, axonal injury, and oligodendrocyte loss in the mice. Triptolide also improved cognitive function in novel object recognition test and Morris water maze test. In primary oligodendrocytes following oxygen-glucose deprivation (OGD), application of triptolide (0.001-0.1 nM) exerted concentration-dependent protection. We revealed that the protective effect of triptolide resulted from its inhibition of oligodendrocyte apoptosis via increasing the phosphorylation of the Src/Akt/GSK3β pathway. Moreover, triptolide suppressed microglial activation and proinflammatory cytokines expression after chronic cerebral hypoperfusion in mice and in BV2 microglial cells following OGD, which also contributing to its alleviation of white matter injury. Importantly, mice received triptolide at the dose of 20 μg·kg^-1·d^-1 did not show hepatotoxicity and nephrotoxicity even after chronic treatment. Thus, our results highlight that triptolide alleviates whiter matter injury induced by chronic cerebral hypoperfusion through direct protection against oligodendrocyte apoptosis and indirect protection by inhibition of microglial inflammation. Triptolide may have novel indication in clinic such as the treatment of chronic cerebral hypoperfusion-induced SIVD.

Tubulin and Tubulin Posttranslational Modifications in Alzheimer's Disease and Vascular Dementia

Alzheimer's disease (AD) and vascular dementia (VaD) are the two most common forms of dementia in older people. Although these two dementia types differ in their etiology, they share many pathophysiological and morphological features, including neuronal loss, which is associated with the microtubule (MT) destabilization. Stabilization of MTs is achieved in different ways: through interactions with MT binding proteins (MTBP) or by posttranslational modifications (PTMs) of tubulin. Polyglutamylation and tyrosination are two foremost PTMs that regulate the interaction between MTs and MTBPs, and play, therefore, a role in neurodegeneration. In this review, we summarize key information on tubulin PTMs in relation to AD and VaD and address the importance of studying further the tubulin code to reveal sites of potential intervention in development of novel and effective dementia therapy.

HDACi protects against vascular cognitive impairment from CCH injury via induction of BDNF-related AMPA receptor activation

We previously showed a hydroxamic acid‐based histone deacetylase inhibitor (HDACi), compound 13, provides neuroprotection against chronic cerebral hypoperfusion (CCH) both in vitro under oxygen‐glucose deprivation (OGD) conditions and in vivo under bilateral common carotid artery occlusion (BCCAO) conditions. Intriguingly, the protective effect of this HDACi is via H3K14 or H4K5 acetylation–mediated differential BDNF isoform activation. BDNF is involved in cell proliferation and differentiation in development, synaptic plasticity and in learning and memory related with receptors or synaptic proteins. B6 mice underwent BCCAO and were randomized into 4 groups; a sham without BCCAO (sham), BCCAO mice injected with DMSO (DMSO), mice injected with HDACi‐compound 13 (compound 13) and mice injected with suberoylanilide hydroxamic acid (SAHA). The cortex and hippocampus of mice were harvested at 3 months after BCCAO, and levels of BDNF, AMPA receptor and dopamine receptors (D1, D2 and D3) were studied using Western blotting analysis or immunohistochemistry. We found that the AMPA receptor plays a key role in the molecular mechanism of this process by modulating HDAC. This protective effect of HDACi may be through BDNF; therefore, activation of this downstream signalling molecule, for example by AMPA receptors, could be a therapeutic target or intervention applied under CCH conditions.

HDAC inhibitor protects chronic cerebral hypoperfusion and oxygen-glucose deprivation injuries via H3K14 and H4K5 acetylation-mediated BDNF expression

Vascular dementia (VaD) is the second most common cause of dementia, but the treatment is still lacking. Although many studies have reported that histone deacetylase inhibitors (HDACis) confer protective effects against ischemic and hypoxic injuries, their role in VaD is still uncertain. Previous studies shown, one HDACi protected against cognitive decline in animals with chronic cerebral hypoperfusion (CCH). However, the underlying mechanisms remain elusive. In this study, we tested several 10,11‐dihydro‐5H‐dibenzo[b,f]azepine hydroxamates, which act as HDACis in the CCH model (in vivo), and SH‐SY5Y (neuroblastoma cells) with oxygen‐glucose deprivation (OGD, in vitro). We identified a compound 13, which exhibited the best cell viability under OGD. The compound 13 could increase, in part, the protein levels of brain‐derived neurotrophic factor (BDNF). It increased acetylation status on lysine 14 residue of histone 3 (H3K14) and lysine 5 of histone 4 (H4K5). We further clarified which promoters (I, II, III, IV or IX) could be affected by histone acetylation altered by compound 13. The results of chromatin immunoprecipitation and Q‐PCR analysis indicate that an increase in H3K14 acetylation leads to an increase in the expression of BDNF promoter II, while an increase in H4K5 acetylation results in an increase in the activity of BDNF promoter II and III. Afterwards, these cause an increase in the expression of BDNF exon II, III and coding exon IX. In summary, the HDACi compound 13 may increase BDNF specific isoforms expression to rescue the ischemic and hypoxic injuries through changes of acetylation on histones.