Resveratrol Abrogates Hypoxia-Induced Up-Regulation of Exosomal Amyloid-β Partially by Inhibiting CD147

Exosomes: A Cellular Communication Medium That Has Multiple Effects On Brain Diseases

Exosomes, as membranous vesicles generated by multiple cell types and secreted to extracellular space, play a crucial role in a range of brain injury-related brain disorders by transporting diverse proteins, RNA, DNA fragments, and other functional substances. The nervous system's pathogenic mechanisms are complicated, involving pathological processes like as inflammation, apoptosis, oxidative stress, and autophagy, all of which result in blood-brain barrier damage, cognitive impairment, and even loss of normal motor function. Exosomes have been linked to the incidence and progression of brain disorders in recent research. As a result, a thorough knowledge of the interaction between exosomes and brain diseases may lead to the development of more effective therapeutic techniques that may be implemented in the clinic. The potential role of exosomes in brain diseases and the crosstalk between exosomes and other pathogenic processes were discussed in this paper. Simultaneously, we noted the delicate events in which exosomes as a media allow the brain to communicate with other tissues and organs in physiology and disease, and compiled a list of natural compounds that modulate exosomes, in order to further improve our understanding of exosomes and propose new ideas for treating brain disorders.

Dietary Phenolic Compounds: Their Health Benefits and Association with the Gut Microbiota

Oxidative stress causes various diseases, such as type II diabetes and dyslipidemia, while antioxidants in foods may prevent a number of diseases and delay aging by exerting their effects in vivo. Phenolic compounds are phytochemicals such as flavonoids which consist of flavonols, flavones, flavanonols, flavanones, anthocyanidins, isoflavones, lignans, stilbenoids, curcuminoids, phenolic acids, and tannins. They have phenolic hydroxyl groups in their molecular structures. These compounds are present in most plants, are abundant in nature, and contribute to the bitterness and color of various foods. Dietary phenolic compounds, such as quercetin in onions and sesamin in sesame, exhibit antioxidant activity and help prevent cell aging and diseases. In addition, other kinds of compounds, such as tannins, have larger molecular weights, and many unexplained aspects still exist. The antioxidant activities of phenolic compounds may be beneficial for human health. On the other hand, metabolism by intestinal bacteria changes the structures of these compounds with antioxidant properties, and the resulting metabolites exert their effects in vivo. In recent years, it has become possible to analyze the composition of the intestinal microbiota. The augmentation of the intestinal microbiota by the intake of phenolic compounds has been implicated in disease prevention and symptom recovery. Furthermore, the “brain–gut axis”, which is a communication system between the gut microbiome and brain, is attracting increasing attention, and research has revealed that the gut microbiota and dietary phenolic compounds affect brain homeostasis. In this review, we discuss the usefulness of dietary phenolic compounds with antioxidant activities against some diseases, their biotransformation by the gut microbiota, the augmentation of the intestinal microflora, and their effects on the brain–gut axis.

Neurological aspects of SARS-CoV-2 infection: lipoproteins and exosomes as Trojan horses

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) primarily targets lipid-producing cells for viral tropism. In this review, we connect systemic lipid couriers, particularly high-density lipoproteins (HDLs) and exosomes, with the neurological facets of SARS-CoV-2 infection. We discuss how SARS-CoV-2 preferentially targets lipid-secreting cells and usurps host cell lipid metabolism for efficient replication and systemic spreading. Besides providing natural veils for viral materials against host immunity, the inherent properties of some of these endogenous lipid particles to traverse the blood-brain barrier (BBB) also offer alternative routes for SARS-CoV-2 neurotropism. Importantly, virus-driven neurological aberrations mediated by HDLs and exosomes are fueled by lipid rafts, which are implicated in the production and transmigration of these lipid particles across the BBB. Finally, we discuss how repurposing existing drugs targeting lipid rafts and cholesterol homeostasis may be beneficial toward alleviating the global coronavirus disease 2019 (COVID-19) disease burden.

The potential role of extracellular vesicles in bioactive compound-based therapy: A review of recent developments

Recent studies have explored the field of extracellular vesicles (EVs), driving an increasing interest in their application to human health. EVs have unique physicochemical traits to participate in intercellular communication, thus fostering the idea of using EVs to yield synergistic, preventive, and therapeutic effects. Many reports have shown that EVs contain natural bioactive compounds, such as lipids, proteins, RNA, and other active components that regulate biological processes, thereby contributing to human health. Therefore, in this review, we comprehensively elucidate various facets of the relationship between EVs and bioactive compounds that modulate EVs contents, including RNAs and proteins, discussing different forms of biological regulation. The use of EVs for cargo-loading bioactive compounds to exert biological functions and methods to load bioactive compounds into EVs are also discussed. This review highlighted the effect of EV-delivered bioactive compounds on several therapeutic mechanisms and applications, providing new insight into nutrition and pharmacology.

Hypoxia Induced Changes of Exosome Cargo and Subsequent Biological Effects

Exosomes are small extracellular vesicles that are secreted by almost all types of cells and exist in almost all extracellular spaces. As an important mediator of intercellular communication, exosomes encapsulate the miRNA, lncRNA, cirRNA, mRNA, cytokine, enzyme, lipid, and other components from the cytoplasm into its closed single membrane structure and transfer them to recipient units in an autocrine, paracrine, or endocrine manner. Hypoxia is a state of low oxygen tension and is involved in many pathological processes. Hypoxia influences the size, quantity, and expression of exosome cargos. Exosomes derived from hypoxic tumor cells transfer genetics, proteins, and lipids to the recipient units to exert pleiotropic effects. Different donor cells produce different cargo contents, target different recipient units and lead to different biological effects. Hypoxic exosomes derived from tumor cells uptaken by normoxic tumor cells lead to promoted proliferation, migration, and invasion; uptaken by extracellular space or liver lead to promoted metastasis; uptaken by endothelial cells lead to promoted angiogenesis; uptaken by immune cells lead to promoted macrophage polarization and changed tumor immune microenvironment. In addition to various types of tumors, hypoxic exosomes also participate in the development of diseases in the cardiovascular system, neuron system, respiratory system, hematology system, endocrine system, urinary system, reproduction system, and skeletomuscular system. Understanding the special characteristics of hypoxic exosomes provide new insight into elaborating the pathogenesis of hypoxia related disease. This review summarizes hypoxia induced cargo changes and the biological effects of hypoxic exosomes in tumors and non-malignant diseases in different systems.

Dietary Plant Polyphenols as the Potential Drugs in Neurodegenerative Diseases: Current Evidence, Advances, and Opportunities

Neurodegenerative diseases, including Alzheimer’s disease (AD), Parkinson’s disease (PD), and Huntington’s disease (HD), are characterized by the progressive degeneration of neurons. Although the etiology and pathogenesis of neurodegenerative diseases have been studied intensively, the mechanism is still in its infancy. In general, most neurodegenerative diseases share common molecular mechanisms, and multiple risks interact and promote the pathologic process of neurogenerative diseases. At present, most of the approved drugs only alleviate the clinical symptoms but fail to cure neurodegenerative diseases. Numerous studies indicate that dietary plant polyphenols are safe and exhibit potent neuroprotective effects in various neurodegenerative diseases. However, low bioavailability is the biggest obstacle for polyphenol that largely limits its adoption from evidence into clinical practice. In this review, we summarized the widely recognized mechanisms associated with neurodegenerative diseases, such as misfolded proteins, mitochondrial dysfunction, oxidative damage, and neuroinflammatory responses. In addition, we summarized the research advances about the neuroprotective effect of the most widely reported dietary plant polyphenols. Moreover, we discussed the current clinical study and application of polyphenols and the factors that result in low bioavailability, such as poor stability and low permeability across the blood-brain barrier (BBB). In the future, the improvement of absorption and stability, modification of structure and formulation, and the combination therapy will provide more opportunities from the laboratory into the clinic for polyphenols. Lastly, we hope that the present review will encourage further researches on natural dietary polyphenols in the treatment of neurodegenerative diseases.

Resveratrol Alleviates Ischemic Brain Injury by Inhibiting the Activation of Pro-Inflammatory Microglia Via the CD147/MMP-9 Pathway

OBJECTIVE

Ischemic stroke is one of the most common diseases with high mortality and disability. This study was intended to investigate the mechanism of resveratrol (RES) regulating microglia activation through the CD147/matrix metalloproteinase-9 (MMP-9) pathway on ischemic stroke.

METHODS

The middle cerebral artery occlusion (MCAO) mouse model and oxygen and glucose deprivation (OGD) cell model were established. The behavioral defects, neuronal damage, cerebral infarction volume, and histopathological changes were assessed in MCAO mice. The activation of pro-inflammatory microglia CD86⁺/Iba-1⁺ and anti-inflammatory microglia CD206⁺/Iba-1⁺ was detected. The expressions of pro-inflammatory microglia markers (CD11b, CD16) and cytokines (TNF-α, IL-1β, and IL-6) were measured. The activation of the CD147/MMP-9 pathway was detected and its effect on microglia activation was assessed.

RESULTS

After RES administration, the neuronal dysfunction, infarct volume, and morphological changes of neurons were improved in MCAO mice. Meanwhile, the motivation of pro-inflammatory microglia and the release of inflammatory factors were repressed. RES suppressed the stimulation of OGD/R microglia and the release of inflammatory factors. The expression of CD147 and MMP-9 in primary microglia was up-regulated. Inhibition of CD147 can reduce pro-inflammatory microglia activation by inhibiting MMP-9 expression. RES inhibited the CD147/MMP-9 axis in OGD/R microglia, and overexpression of CD147 partially reversed the inhibitory effect of RES on the activation and release of inflammatory factors in OGD/R microglia.

CONCLUSION

RES restrained the stimulation of pro-inflammatory microglia by down-regulating the CD147/MMP-9 axis, and thus protected against ischemic brain injury.

Implications of exosomes derived from cholesterol-accumulated astrocytes in Alzheimer's disease pathology

Amyloid β (Aβ) peptides generated from the amyloid precursor protein (APP) play a critical role in the development of Alzheimer's disease (AD) pathology. Aβ-containing neuronal exosomes, which represent a novel form of intercellular communication, have been shown to influence the function/vulnerability of neurons in AD. Unlike neurons, the significance of exosomes derived from astrocytes remains unclear. In this study, we evaluated the significance of exosomes derived from U18666A-induced cholesterol-accumulated astrocytes in the development of AD pathology. Our results show that cholesterol accumulation decreases exosome secretion, whereas lowering cholesterol increases exosome secretion, from cultured astrocytes. Interestingly, exosomes secreted from U18666A-treated astrocytes contain higher levels of APP, APP-C-terminal fragments, soluble APP, APP secretases and Aβ1-40 than exosomes secreted from control astrocytes. Furthermore, we show that exosomes derived from U18666A-treated astrocytes can lead to neurodegeneration, which is attenuated by decreasing Aβ production or by neutralizing exosomal Aβ peptide with an anti-Aβ antibody. These results, taken together, suggest that exosomes derived from cholesterol-accumulated astrocytes can play an important role in trafficking APP/Aβ peptides and influencing neuronal viability in the affected regions of the AD brain.

Endothelial genetic deletion of CD147 induces changes in the dual function of the blood-brain barrier and is implicated in Alzheimer's disease

AIMS

The blood-brain barrier (BBB) is a specialized and indispensable structure in brain blood vessels that is damaged during Alzheimer's disease (AD). CD147 is expressed on the BBB and deeply engaged in the AD pathological process. In this study, we aimed to provide a better understanding of the roles of CD147 in BBB function in health and neurodegenerative disease.

METHODS AND RESULTS

We measured CD147 expression in mouse brains and demonstrated that CD147 is exclusively expressed in brain endothelial cells (BECs), and its expression decreases with age. After constructing endothelial-specific CD147 knockout mice, we performed RNA-sequencing on BECs isolated from mice of different ages as well as a range of database analyses. We found that endothelial CD147 is essential for the dual functions of the BBB, including barrier maintenance and transporter regulation. This study also shows that CD147 plays a pivotal role in neurodegenerative diseases, particularly in AD.

CONCLUSIONS

Our findings suggested that targeting CD147 in BECs may represent a novel therapeutic strategy, which promoted the design of future experimental investigations and the mechanistic understanding of neurodegenerative diseases.

Ivabradine induces cardiac protection by preventing cardiogenic shock-induced extracellular matrix degradation

INTRODUCTION AND OBJECTIVES

Ivabradine reduces heart rate by blocking the I(f) current and preserves blood pressure and stroke volume through unknown mechanisms. Caveolin-3 protects the heart by forming protein complexes with several proteins, including extracellular matrix (ECM)-metalloproteinase-inducer (EMMPRIN) and hyperpolarization-activated cyclic nucleotide-gated channel 4 (HN4), a target of ivabradine. We hypothesized that ivabradine might also exert cardioprotective effects through inhibition of ECM degradation.

METHODS

In a porcine model of cardiogenic shock, we studied the effects of ivabradine on heart integrity, the levels of MMP-9 and EMMPRIN, and the stability of caveolin-3/HCN4 protein complexes with EMMPRIN.

RESULTS

Administration of 0.3 mg/kg ivabradine significantly reduced cardiogenic shock-induced ventricular necrosis and expression of MMP-9 without affecting EMMPRIN mRNA, protein, or protein glycosylation (required for MMP activation). However, ivabradine increased the levels of the caveolin-3/LG-EMMPRIN (low-glycosylated EMMPRIN) and caveolin-3/HCN4 protein complexes and decreased that of a new complex between HCN4 and high-glycosylated EMMPRIN formed in response to cardiogenic shock. We next tested whether caveolin-3 can bind to HCN4 and EMMPRIN and found that the HCN4/EMMPRIN complex was preserved when we silenced caveolin-3 expression, indicating a direct interaction between these 2 proteins. Similarly, EMMPRIN-silenced cells showed a significant reduction in the binding of caveolin-3/HCN4, which regulates the I(f) current, suggesting that, rather than a direct interaction, both proteins bind to EMMPRIN.

CONCLUSIONS

In addition to inhibition of the I(f) current, ivabradine may induce cardiac protection by inhibiting ECM degradation through preservation of the caveolin-3/LG-EMMPRIN complex and control heart rate by stabilizing the caveolin-3/HCN4 complex.

Resveratrol-induced apoptosis is associated with regulating the miR-492/CD147 pathway in malignant melanoma cells

Resveratrol (RES) as a natural phytoalexin has anti-tumor effects on various cancers through its pro-apoptotic activities. Our aim was to determine that RES induces apoptosis in melanoma cells by regulating miR-492 resulting in decreased CD147 expression. We treated A375 and SK-MEL-28 melanoma cells via RES at different concentrations and time-points. The results have shown that the inhibition rate of A375 and SK-MEL-28 was significantly increased after RES treatment. Subsequently, we investigated cell apoptosis by flow cytometry, as well as detected apoptotic-associated proteins including PARP, Caspase-3, Bcl-2, and Bax by western blotting. Meanwhile, the expression of miR-492 and CD147 was analyzed. We found that RES remarkably induces apoptosis in melanoma cells, along with an upregulation of miR-492 and the inhibition of CD147 expression. Furthermore, the detection of luciferase reporter activity confirmed that miR-492 could target CD147 mRNA, and transfected with mimic miR-492 in cells reduced CD147 expression. We also performed the rescued experiment by using a miR-492 inhibitor in melanoma cells. The results showed that the ability of induced apoptosis by RES in melanoma cells was to be attenuated via inhibiting miR-492 expression resulting in CD147 augment. Finally, we determined that the effect of RES-induced apoptosis in melanoma cells is associated with, at least in part, its ability to regulate the miR-492/CD147 pathway.

Diagnostic and therapeutic potential of exosomes in Alzheimer's disease

Exosomes are small extracellular vesicles released by almost all cell types in physiological and pathological conditions. The exosomal potential to unravel disease mechanisms, or to be used as a source of biomarkers, is being explored, in particularly in the field of neurodegenerative diseases. Alzheimer's disease (AD) is the most prevalent neurodegenerative disease in the world and exosomes appear to have a relevant role in disease pathogenesis. This review summarizes the current knowledge on exosome contributions to AD as well as their use as disease biomarker resources or therapeutic targets. The most recent findings with respect to both protein and miRNA biomarker candidates for AD, herein described, highlight the state of the art in this field and encourage the use of exosomes derived from biofluids in clinical practice in the near future.

Resveratrol targeting tau proteins, amyloid-beta aggregations, and their adverse effects: An updated review

Resveratrol (Res) is a non-flavonoid compound with pharmacological actions such as antioxidant, antiinflammatory, hepatoprotective, antidiabetes, and antitumor. This plant-derived chemical has a long history usage in treatment of diseases. The excellent therapeutic impacts of Res and its capability in penetration into blood-brain barrier have made it an appropriate candidate in the treatment of neurological disorders (NDs). Tau protein aggregations and amyloid-beta (Aβ) deposits are responsible for the induction of NDs. A variety of studies have elucidated the role of these aggregations in NDs and the underlying molecular pathways in their development. In the present review, based on the recently published articles, we describe that how Res administration could inhibit amyloidogenic pathway and stimulate processes such as autophagy to degrade Aβ aggregations. Besides, we demonstrate that Res supplementation is beneficial in dephosphorylation of tau proteins and suppressing their aggregations. Then, we discuss molecular pathways and relate them to the treatment of NDs.

How hypoxia regulate exosomes in ischemic diseases and cancer microenvironment?

Exosomes, as natural occurring vesicles, play highly important roles in the behavior and fate of ischemic diseases and different tumors. Secretion, composition, and function of exosomes are remarkably influenced by hypoxia in ischemic diseases and tumor microenvironment. Exosomes secreted from hypoxic cells affect development, growth, angiogenesis, and progression in ischemic diseases and tumors through a variety of signaling pathways. In this review article, we discuss how hypoxia affects the quantity and quality of exosomes, and review the mechanisms by which hypoxic cell-derived exosomes regulate ischemic cell behaviors in both cancerous and noncancerous cells.