miR-204-3p/Nox4 Mediates Memory Deficits in a Mouse Model of Alzheimer's Disease

NOX4 exacerbates Parkinson's disease pathology by promoting neuronal ferroptosis and neuroinflammation

JOURNAL/nrgr/04.03/01300535-202507000-00026/figure1/v/2024-09-09T124005Z/r/image-tiff Parkinson's disease is primarily caused by the loss of dopaminergic neurons in the substantia nigra compacta. Ferroptosis, a novel form of regulated cell death characterized by iron accumulation and lipid peroxidation, plays a vital role in the death of dopaminergic neurons. However, the molecular mechanisms underlying ferroptosis in dopaminergic neurons have not yet been completely elucidated. NADPH oxidase 4 is related to oxidative stress, however, whether it regulates dopaminergic neuronal ferroptosis remains unknown. The aim of this study was to determine whether NADPH oxidase 4 is involved in dopaminergic neuronal ferroptosis, and if so, by what mechanism. We found that the transcriptional regulator activating transcription factor 3 increased NADPH oxidase 4 expression in dopaminergic neurons and astrocytes in an 1-methyl-4-phenyl-1,2,3,6 tetrahydropyridine-induced Parkinson's disease model. NADPH oxidase 4 inhibition improved the behavioral impairments observed in the Parkinson's disease model animals and reduced the death of dopaminergic neurons. Moreover, NADPH oxidase 4 inhibition reduced lipid peroxidation and iron accumulation in the substantia nigra of the Parkinson's disease model animals. Mechanistically, we found that NADPH oxidase 4 interacted with activated protein kinase C α to prevent ferroptosis of dopaminergic neurons. Furthermore, by lowering the astrocytic lipocalin-2 expression, NADPH oxidase 4 inhibition reduced 1-methyl-4-phenyl-1,2,3,6 tetrahydropyridine-induced neuroinflammation. These findings demonstrate that NADPH oxidase 4 promotes ferroptosis of dopaminergic neurons and neuroinflammation, which contribute to dopaminergic neuron death, suggesting that NADPH oxidase 4 is a possible therapeutic target for Parkinson's disease.

NADPH oxidase 4 (NOX4) as a biomarker and therapeutic target in neurodegenerative diseases

Diseases like Alzheimer's and Parkinson's diseases are defined by inflammation and the damage neurons undergo due to oxidative stress. A primary reactive oxygen species contributor in the central nervous system, NADPH oxidase 4, is viewed as a potential therapeutic touchstone and indicative marker for these ailments. This in-depth review brings to light distinct features of NADPH oxidase 4, responsible for generating superoxide and hydrogen peroxide, emphasizing its pivotal role in activating glial cells, inciting inflammation, and disturbing neuronal functions. Significantly, malfunctioning astrocytes, forming the majority in the central nervous system, play a part in advancing neurodegenerative diseases, due to their reactive oxygen species and inflammatory factor secretion. Our study reveals that aiming at NADPH oxidase 4 within astrocytes could be a viable treatment pathway to reduce oxidative damage and halt neurodegenerative processes. Adjusting NADPH oxidase 4 activity might influence the neuroinflammatory cytokine levels, including myeloperoxidase and osteopontin, offering better prospects for conditions like Alzheimer's disease and Parkinson's disease. This review sheds light on the role of NADPH oxidase 4 in neural degeneration, emphasizing its drug target potential, and paving the path for novel treatment approaches to combat these severe conditions.

Microglia and Astrocytes in Alzheimer's Disease: Significance and Summary of Recent Advances

Alzheimer's disease, one of the most common forms of dementia, is characterized by a slow progression of cognitive impairment and neuronal loss. Currently, approved treatments for AD are hindered by various side effects and limited efficacy. Despite considerable research, practical treatments for AD have not been developed. Increasing evidence shows that glial cells, especially microglia and astrocytes, are essential in the initiation and progression of AD. During AD progression, activated resident microglia increases the ability of resting astrocytes to transform into reactive astrocytes, promoting neurodegeneration. Extensive clinical and molecular studies show the involvement of microglia and astrocyte-mediated neuroinflammation in AD pathology, indicating that microglia and astrocytes may be potential therapeutic targets for AD. This review will summarize the significant and recent advances of microglia and astrocytes in the pathogenesis of AD in three parts. First, we will review the typical pathological changes of AD and discuss microglia and astrocytes in terms of function and phenotypic changes. Second, we will describe microglia and astrocytes' physiological and pathological role in AD. These roles include the inflammatory response, "eat me" and "don't eat me" signals, Aβ seeding, propagation, clearance, synapse loss, synaptic pruning, remyelination, and demyelination. Last, we will review the pharmacological and non-pharmacological therapies targeting microglia and astrocytes in AD. We conclude that microglia and astrocytes are essential in the initiation and development of AD. Therefore, understanding the new role of microglia and astrocytes in AD progression is critical for future AD studies and clinical trials. Moreover, pharmacological, and non-pharmacological therapies targeting microglia and astrocytes, with specific studies investigating microglia and astrocyte-mediated neuronal damage and repair, may be a promising research direction for future studies regarding AD treatment and prevention.

NOX4-mediated astrocyte ferroptosis in Alzheimer's disease

This study investigates NADPH oxidase 4 (NOX4) involvement in iron-mediated astrocyte cell death in Alzheimer's Disease (AD) using single-cell sequencing data and transcriptomes. We analyzed AD single-cell RNA sequencing data, identified astrocyte marker genes, and explored biological processes in astrocytes. We integrated AD-related chip data with ferroptosis-related genes, highlighting NOX4. We validated NOX4's role in ferroptosis and AD in vitro and in vivo. Astrocyte marker genes were enriched in AD, emphasizing their role. NOX4 emerged as a crucial player in astrocytic ferroptosis in AD. Silencing NOX4 mitigated ferroptosis, improved cognition, reduced Aβ and p-Tau levels, and alleviated mitochondrial abnormalities. NOX4 promotes astrocytic ferroptosis, underscoring its significance in AD progression.

Thymoquinone ameliorates symptoms of Parkinson's disease in a 6-OHDA rat model by downregulation of miR-204-3p

microRNAs (miRNAs) play a significant role in the pathophysiology of Parkinson's disease. In this study, we evaluated the neuroprotective effect of thymoquinone on the expression profiles of miRNA and cognitive functions in the 6-hydroxydopamine (6-OHDA)-induced Parkinson's model. Male adult Wistar albino rats (200-230 g, n  = 36) were randomly assigned to six groups: Sham, thymoquinone (10 mg/kg, p.o.), 6-OHDA, 6-OHDA + thymoquinone (10 mg/kg), 6-OHDA + thymoquinone (20 mg/kg), and 6-OHDA + thymoquinone (50 mg/kg). Behavioral changes were detected using the open field and the elevated plus maze tests. The mature 728 miRNA expressions were evaluated by miRNA microarray (GeneChip miRNA 4.0). Ten miRNAs were selected (rno-miR-212-5p, rno-miR-146b-5p, rno-miR-150-5p, rno-miR-29b-2-5p, rno-miR-126a-3p, rno-miR-187-3p, rno-miR-34a-5p, rno-miR-181d-5p, rno-miR-204-3p, and rno-miR-30c-2-3p) and confirmed by real-time PCR. Striatum samples were stained with hematoxylin-eosin to determine the effect of dopaminergic lesions. One-way ANOVA test and independent sample t -test were used for statistical analyses. rno-miR-204-3p was upregulated at 6-OHDA and downregulated at the 50 mg/kg dose of thymoquinone. In conclusion, thymoquinone at a dose of 50 mg/kg ameliorates symptoms of Parkinson's disease in a 6-OHDA rat model by downregulation of miR-204-3p. Also, the results showed that thymoquinone can improve locomotor activity and willing exploration and decreased anxiety. Therefore, thymoquinone can be used as a therapeutic agent.

MYPT1SMKO Mice Function as a Novel Spontaneous Age- and Hypertension-Dependent Animal Model of CSVD

Cerebral small vessel disease (CSVD) is the most common progressive vascular disease that causes vascular dementia. Aging and hypertension are major contributors to CSVD, but the pathophysiological mechanism remains unclear, mainly due to the lack of an ideal animal model. Our previous study revealed that vascular smooth muscle cell (VSMC)-specific myosin phosphatase target subunit 1 (MYPT1) knockout (MYPT1SMKO) leads to constant hypertension, prompting us to explore whether hypertensive MYPT1SMKO mice can be considered a novel CSVD animal model. Here, we found that MYPT1SMKO mice displayed age-dependent CSVD-like neurobehaviors, including decreased motion speed, anxiety, and cognitive decline. MYPT1SMKO mice exhibited remarkable white matter injury compared with control mice, as shown by the more prominent loss of myelin at 12 months of age. Additionally, MYPT1SMKO mice were found to exhibit CSVD-like small vessel impairment, including intravascular hyalinization, perivascular space enlargement, and microbleed and blood-brain barrier (BBB) disruption. Last, our results revealed that the brain of MYPT1SMKO mice was characterized by an exacerbated inflammatory microenvironment, which is similar to patients with CSVD. In light of the above structural and functional phenotypes that closely mimic the conditions of human CSVD, we suggest that MYPT1SMKO mice are a novel age- and hypertension-dependent animal model of CSVD.

miR-145a-5p/SIK1/cAMP-dependent alteration of synaptic structural plasticity drives cognitive impairment induced by coke oven emissions

Exposure to fine particulate matter (PM) is associated with the neurodegenerative diseases. Coke oven emissions (COEs) in occupational environment are important sources of PM. However, its neurotoxicity is still unclear. Therefore, evaluating the toxicological effects of COE on the nervous system is necessary. In the present study, we constructed mouse models of COE exposure by tracheal instillation. Mice exposed to COE showed signs of cognitive impairment. This was accompanied by a decrease in miR-145a-5p and an increase in SIK1 expression in the hippocampus, along with synaptic structural damage. Our results demonstrated that COE-induced miR-145a-5p downregulation could increase the expression of SIK1 and phosphorylated SIK1, inhibiting the cAMP/PKA/CREB pathway by activating PDE4D, which was associated with reduced synaptic structural plasticity. Furthermore, restoring of miR-145a-5p expression based on COE exposure in HT22 cells could partially reversed the negative effects of COE exposure through the SIK1/PDE4D/cAMP axis. Collectively, our findings link epigenetic regulation with COE-induced neurotoxicity and imply that miR-145a-5p could be an early diagnostic marker for neurological diseases in patients with COE occupational exposure.

The biomedical application of inorganic metal nanoparticles in aging and aging-associated diseases

Aging and aging-associated diseases (AAD), including neurodegenerative disease, cancer, cardiovascular diseases, and diabetes, are inevitable process. With the gradual improvement of life style, life expectancy is gradually extended. However, the extended lifespan has not reduced the incidence of disease, and most elderly people are in ill-health state in their later years. Hence, understanding aging and AAD are significant for reducing the burden of the elderly. Inorganic metal nanoparticles (IMNPs) predominantly include gold, silver, iron, zinc, titanium, thallium, platinum, cerium, copper NPs, which has been widely used to prevent and treat aging and AAD due to their superior properties (essential metal ions for human body, easily synthesis and modification, magnetism). Therefore, a systematic review of common morphological alternations of senescent cells, altered genes and signal pathways in aging and AAD, and biomedical applications of IMNPs in aging and AAD is crucial for the further research and development of IMNPs in aging and AAD. This review focus on the existing research on cellular senescence, aging and AAD, as well as the applications of IMNPs in aging and AAD in the past decade. This review aims to provide cutting-edge knowledge involved with aging and AAD, the application of IMNPs in aging and AAD to promote the biomedical application of IMNPs in aging and AAD.

Progressive reduction of nuclear receptor Nr4a1 mediates age-dependent cognitive decline

INTRODUCTION

Cognitive decline progresses with age, and Nr4a1 has been shown to participate in memory functions. However, the relationship between age-related Nr4a1 reduction and cognitive decline is undefined.

METHODS

Nr4a1 expressions were evaluated by quantitative PCR and immunochemical approaches. The cognition of mice was examined by multiple behavioral tests. Patch-clamp experiments were conducted to investigate the synaptic function.

RESULTS

NR4A1 in peripheral blood mononuclear cells decreased with age in humans. In the mouse brain, age-dependent Nr4a1 reduction occurred in the hippocampal CA1. Deleting Nr4a1 in CA1 pyramidal neurons (PyrNs) led to the impairment of cognition and excitatory synaptic function. Mechanistically, Nr4a1 enhanced TrkB expression via binding to its promoter. Blocking TrkB compromised the cognitive amelioration with Nr4a1-overexpression in CA1 PyrNs.

DISCUSSION

Our results elucidate the mechanism of Nr4a1-dependent TrkB regulation in cognition and synaptic function, indicating that Nr4a1 is a target for the treatment of cognitive decline.

HIGHLIGHTS

Nr4a1 is reduced in PBMCs and CA1 PyrNs with aging. Nr4a1 ablation in CA1 PyrNs impaired cognition and excitatory synaptic function. Nr4a1 overexpression in CA1 PyrNs ameliorated cognitive impairment of aged mice. Nr4a1 bound to TrkB promoter to enhance transcription. Blocking TrkB function compromised Nr4a1-induced cognitive improvement.

miR-3940-5p reduces amyloid β production via selectively targeting PSEN1

Alzheimer's disease (AD) is a progressive neurodegenerative disorder characterized by the accumulation of amyloid beta (Aβ) in brain. Mounting evidence has revealed critical roles of microRNAs (miRNAs) in AD pathogenesis; however, the miRNAs directly targeting presenilin1 (PSEN1), which encodes the catalytic core subunit of γ-secretase that limits the production of Aβ from amyloid precursor protein (APP), are extremely understudied. The present study aimed to identify miRNAs targeting PSEN1 and its effect on Aβ production. This study first predicted 5 candidate miRNAs that may target PSEN1,through websites such as TargetScan, miRDB, and miRwalk. Subsequently, the targeting specificity of the candidate miRNAs towards PS1 was validated using dual-luciferase reporter assays. To investigate the regulatory effect of miR-3940-5p on gene expression based on its targeting of PS1, miR-3940-5p mimics or inhibitors were transiently transfected into SH-SY5Y cells. Changes in PSEN1 transcription and translation in the tested cells were detected using RT-qPCR and Western Blot, respectively. Finally, to explore whether miR-3940-5p affects Aβ production, SH-SY5Y APPswe cells overexpressing the Swedish mutant type of APP were transiently transfected with miR-3940-5p mimics, and the expression level of Aβ was detected using ELISA. The results are as follows: The dual-luciferase reporter assays validated the targeting specificity of miR-3940-5p for PSEN1. Overexpression of miR-3940-5p significantly reduced the mRNA and protein levels of PSEN1 in SH-SY5Y cells. Conversely, inhibition of miR-3940-5p led to an increase in PSEN1 mRNA levels. Transfection of miR-3940-5p mimics into SH-SY5Y-APPswe cells resulted in a significant reduction in Aβ42 and Aβ40. Lentiviral-mediated overexpression of miR-3940-5p significantly decreased the expression of PSEN1 and did not significantly affect the expression of other predicted target genes. Furthermore, stable overexpression of miR-3940-5p in SH-SY5Y-APPswe cells mediated by lentivirus significantly reduced the expression of PSEN1 and the production of Aβ42 and Aβ40. Therefore, our study demonstrates for the first time the functional importance of miR-3940-5p in antagonizing Aβ production through specific and direct targeting of PSEN1.

Recognizing Alzheimer's disease from perspective of oligodendrocytes: Phenomena or pathogenesis?

BACKGROUND

Accumulation of amyloid beta, tau hyperphosphorylation, and microglia activation are the three highly acknowledged pathological factors of Alzheimer's disease (AD). However, oligodendrocytes (OLs) were also widely investigated in the pathogenesis and treatment for AD.

AIMS

We aimed to update the regulatory targets of the differentiation and maturation of OLs, and emphasized the key role of OLs in the occurrence and treatment of AD.

METHODS

This review first concluded the targets of OL differentiation and maturation with AD pathogenesis, and then advanced the key role of OLs in the pathogenesis of AD based on both clinic and basic experiments. Later, we extensively discussed the possible application of the current progress in the diagnosis and treatment of this complex disease.

RESULTS

Molecules involving in OLs' differentiation or maturation, including various transcriptional factors, cholesterol homeostasis regulators, and microRNAs could also participate in the pathogenesis of AD. Clinical data point towards the impairment of OLs in AD patients. Basic research further supports the central role of OLs in the regulation of AD pathologies. Additionally, classic drugs, including donepezil, edaravone, fluoxetine, and clemastine demonstrate their potential in remedying OL impairment in AD models, and new therapeutics from the perspective of OLs is constantly being developed.

CONCLUSIONS

We believe that OL dysfunction is one important pathogenesis of AD. Factors regulating OLs might be biomarkers for early diagnosis and agents stimulating OLs warrant the development of anti-AD drugs.

NRF2 Deficiency Promotes Ferroptosis of Astrocytes Mediated by Oxidative Stress in Alzheimer's Disease

Oxidative stress is involved in the pathogenesis of Alzheimer's disease (AD), which is linked to reactive oxygen species (ROS), lipid peroxidation, and neurotoxicity. Emerging evidence suggests a role of nuclear factor (erythroid-derived 2)-like 2 (Nrf2), a major source of antioxidant response elements in AD. The molecular mechanism of oxidative stress and ferroptosis in astrocytes in AD is not yet fully understood. Here, we aimed to investigate the mechanism by which Nrf2 regulates the ferroptosis of astrocytes in AD. We found decreased expression of Nrf2 and upregulated expression of the ROS marker NADPH oxidase 4 (NOX4) in the frontal cortex from patients with AD and in the cortex of 3×Tg mice compared to wildtype mice. We demonstrated that Nrf2 deficiency led to ferroptosis-dependent oxidative stress-induced ROS with downregulated heme oxygenase-1 and glutathione peroxidase 4 and upregulated cystine glutamate expression. Moreover, Nrf2 deficiency increased lipid peroxidation, DNA oxidation, and mitochondrial fragmentation in mouse astrocytes (mAS, M1800-57). In conclusion, these results suggest that Nrf2 deficiency promotes ferroptosis of astrocytes involving oxidative stress in AD.

Impairments of GABAergic transmission in hippocampus mediate increased susceptibility of epilepsy in the early stage of Alzheimer's disease

BACKGROUND

Patients with Alzheimer's disease (AD) are often co-morbid with unprovoked seizures, making clinical diagnosis and management difficult. Although it has an important role in both AD and epilepsy, abnormal γ-aminobutyric acid (GABA)ergic transmission is recognized only as a compensative change for glutamatergic damage. Neuregulin 1 (NRG1)-ErbB4 signaling can promote GABA release and suppress epileptogenesis, but its effects on cognition in AD are still controversial.

METHODS

Four-month-old APPswe/PS1dE9 mice (APP mice) were used as animal models in the early stage of AD in this study. Acute/chronic chemical-kindling epilepsy models were established with pentylenetetrazol. Electroencephalogram and Racine scores were performed to assess seizures. Behavioral tests were used to assess cognition and emotion. Electrophysiology, western blot and immunofluorescence were performed to detect the alterations in synapses, GABAergic system components and NRG1-ErbB4 signaling. Furthermore, NRG1 was administrated intracerebroventricularly into APP mice and then its antiepileptic and cognitive effects were evaluated.

RESULTS

APP mice had increased susceptibility to epilepsy and resulting hippocampal synaptic damage and cognitive impairment. Electrophysiological analysis revealed decreased GABAergic transmission in the hippocampus. This abnormal GABAergic transmission involved a reduction in the number of parvalbumin interneurons (PV+ Ins) and decreased levels of GABA synthesis and transport. We also found impaired NRG1-ErbB4 signaling which mediated by PV+ Ins loss. And NRG1 administration could effectively reduce seizures and improve cognition in four-month-old APP mice.

CONCLUSION

Our results indicated that abnormal GABAergic transmission mediated hippocampal hyperexcitability, further excitation/inhibition imbalance, and promoted epileptogenesis in the early stage of AD. Appropriate NRG1 administration could down-regulate seizure susceptibility and rescue cognitive function. Our study provided a potential direction for intervening in the co-morbidity of AD and epilepsy.

Dexmedetomidine mitigates neuroinflammation in an Alzheimer's disease mouse model via the miR-204-3p/FBXL7 signaling axis

Alzheimer's disease (AD) is a prevalent neurodegenerative disorder characterized by neuroinflammation. Dexmedetomidine (Dex) is known for its neuroprotective properties in clinical settings. In this study, we investigated the potential of Dex in protecting against neuroinflammation in an AD mouse model induced by amyloid-beta (Aβ) injection. First, in the AD mouse model, Aβ injection were administered, and the model was confirmed through behavioral tests, including the Morris water maze and Y-maze. Neuroinflammatory states in Aβ-injected mice were assessed using hematoxylin and eosin staining and enzyme-linked immunosorbent assay. Expression levels of microRNA (miR)-204-3p and F-box/LRR-repeat protein 7 (FBXL7) in mouse tissues were determined through real-time quantitative polymerase chain reaction and Western blot. The binding interaction between miR-204-3p and FBXL7 was elucidated using dual-luciferase analysis. Aβ-injected mice exhibited cognitive impairment, neuroinflammation, and downregulated miR-204-3p. Upregulation of miR-204-3p reduced inflammatory infiltration and mitigated neuroinflammation in Aβ-injected mice. Dex treatment reduced inflammation in hippocampal tissues of Aβ-injected mice. Dex treatment upregulated miR-204-3p, leading to suppressed FBXL7 expression in tissues. Inhibition of miR-204-3p or overexpression of FBXL7 reversed the alleviating effect of Dex on neuroinflammation in Aβ-injected mice. Overall, Dex increased miR-204-3p expression, resulting in the inhibition of FBXL7, and subsequently alleviated neuroinflammation in Aβ-injected mice.

Molecular Mechanism of SOX18 in Lipopolysaccharide-Induced Injury of Human Umbilical Vein Endothelial Cells

Endothelial dysfunction is associated with the progression of sepsis. This study sought to probe the molecular route of sex-determining region on the Y chromosome-box transcription factor 18 (SOX18) in sepsis-associated endothelial injury. Human umbilical vein endothelial cells (HUVECs) were treated with lipopolysaccharide (LPS) to establish the sepsis cell model. Cell viability, lactate dehydrogenase (LDH) release, oxidative stress (reactive oxygen species/malondialdehyde/superoxide dismutase), and inflammation (interleukin-1β/tumor necrosis factor-α/interleukin-6) were evaluated by cell counting kit-8 assay and relevant assay kits. The expression levels of SOX18, microRNA (miR)-204-5p, and cadherin-2 (CDH2) in cells were determined by real-time quantitative polymerase chain reaction and Western blot assay. The interaction of SOX18, miR-204-5p, and CDH2 was analyzed by chromatin immunoprecipitation and dual-luciferase assay. LPS induced HUVECs injury and downregulation of SOX18. SOX18 overexpression increased cell viability, while decreased LDH activity, oxidative stress, and inflammation. SOX18 bound to the miR-204-5p promoter to promote miR-204-5p expression, and further repressed CDH2 expression. miR-204-5p knockdown and CDH2 overexpression abrogated the protective role of SOX18 in HUVECs injury. Overall, SOX18 alleviated LPS-induced injury of HUVECs by promoting miR-204-5p and repressing CDH2, suggesting it as a potential target for sepsis treatment.

Oxygen metabolism abnormality and Alzheimer's disease: An update

Oxygen metabolism abnormality plays a crucial role in the pathogenesis of Alzheimer's disease (AD) via several mechanisms, including hypoxia, oxidative stress, and mitochondrial dysfunction. Hypoxia condition usually results from living in a high-altitude habitat, cardiovascular and cerebrovascular diseases, and chronic obstructive sleep apnea. Chronic hypoxia has been identified as a significant risk factor for AD, showing an aggravation of various pathological components of AD, such as amyloid β-protein (Aβ) metabolism, tau phosphorylation, mitochondrial dysfunction, and neuroinflammation. It is known that hypoxia and excessive hyperoxia can both result in oxidative stress and mitochondrial dysfunction. Oxidative stress and mitochondrial dysfunction can increase Aβ and tau phosphorylation, and Aβ and tau proteins can lead to redox imbalance, thus forming a vicious cycle and exacerbating AD pathology. Hyperbaric oxygen therapy (HBOT) is a non-invasive intervention known for its capacity to significantly enhance cerebral oxygenation levels, which can significantly attenuate Aβ aggregation, tau phosphorylation, and neuroinflammation. However, further investigation is imperative to determine the optimal oxygen pressure, duration of exposure, and frequency of HBOT sessions. In this review, we explore the prospects of oxygen metabolism in AD, with the aim of enhancing our understanding of the underlying molecular mechanisms in AD. Current research aimed at attenuating abnormalities in oxygen metabolism holds promise for providing novel therapeutic approaches for AD.

CXCR4-BTK axis mediate pyroptosis and lipid peroxidation in early brain injury after subarachnoid hemorrhage via NLRP3 inflammasome and NF-κB pathway

C-X-C chemokine receptor type 4 (CXCR4) is critical for homeostasis of the adaptive and innate immune system in some CNS diseases. Bruton's tyrosine kinase (BTK) is an essential kinase that regulates inflammation in immune cells through multiple signaling pathways. This study aims to explore the effect of CXCR4 and BTK on neuroinflammation in the pathogenesis of early brain injury (EBI) after subarachnoid hemorrhage (SAH). Our results showed that the expression of CXCR4 and p-BTK increased significantly at 24 h after SAH in vivo and in vitro. Ibrutinib improved neurological impairment, BBB disruption, cerebral edema, lipid peroxidation, neuroinflammation and neuronal death at 24 h after SAH. Inhibition of BTK phosphorylation promoted the in vitro transition of hemin-treated proinflammatory microglia to the anti-inflammatory state, inhibited the p-P65 expression and microglial pyroptosis. NLRP3 deficiency can significantly reduce pyroptosis in SAH mice. Moreover, CXCR4 inhibition can suppress NLRP3-mediated pyroptosis, NF-κB activation and NOX2 expression in vitro, and ibrutinib can abolish CXCR4-aggravated BBB damage and pyroptosis in EBI after SAH. The levels of CXCR4 in CSF of SAH patients is significantly increased, and it is positively correlated with GSDMD and IL-1β levels, and have a moderate diagnostic value for outcome at 6-month follow-up. Our findings revealed the effect of CXCR4 and P-BTK on NLRP3-mediated pyroptosis and lipid peroxidation after SAH in vivo and in vitro, and the potential diagnostic role of CXCR4 in CSF of SAH patients. Inhibition of CXCR4-BTK axis can significantly attenuate NLRP3-mediated pyroptosis and lipid peroxidation by regulating NF-κB activation in EBI after SAH.

Non-Coding RNA in Microglia Activation and Neuroinflammation in Alzheimer's Disease

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by complex pathophysiological features. Amyloid plaques resulting from extracellular amyloid deposition and neurofibrillary tangles formed by intracellular hyperphosphorylated tau accumulation serve as primary neuropathological criteria for AD diagnosis. The activation of microglia has been closely associated with these pathological manifestations. Non-coding RNA (ncRNA), a versatile molecule involved in various cellular functions such as genetic information storage and transport, as well as catalysis of biochemical reactions, plays a crucial role in microglial activation. This review aims to investigate the regulatory role of ncRNAs in protein expression by directly targeting genes, proteins, and interactions. Furthermore, it explores the ability of ncRNAs to modulate inflammatory pathways, influence the expression of inflammatory factors, and regulate microglia activation, all of which contribute to neuroinflammation and AD. However, there are still significant controversies surrounding microglial activation and polarization. The categorization into M1 and M2 phenotypes may oversimplify the intricate and multifaceted regulatory processes in microglial response to neuroinflammation. Limited research has been conducted on the role of ncRNAs in regulating microglial activation and inducing distinct polarization states in the context of neuroinflammation. Moreover, the regulatory mechanisms through which ncRNAs govern microglial function continue to be refined. The current understanding of ncRNA regulatory pathways involved in microglial activation remains incomplete and may be influenced by spatial, temporal, and tissue-specific factors. Therefore, further in-depth investigations are warranted. In conclusion, there are ongoing debates and uncertainties regarding the activation and polarization of microglial cells, particularly concerning the categorization into M1 and M2 phenotypes. The study of ncRNA regulation in microglial activation and polarization, as well as its mechanisms, is still in its early stages and requires further investigation. However, this review offers new insights and opportunities for therapeutic approaches in AD. The development of ncRNA-based drugs may hold promise as a new direction in AD treatment.

Inhibition of NOX4 with GLX351322 alleviates acute ocular hypertension-induced retinal inflammation and injury by suppressing ROS mediated redox-sensitive factors activation

Reactive oxygen species (ROS) overproduction plays an essential role in the etiology of ischemic/hypoxic retinopathy caused by acute glaucoma. NADPH oxidase (NOX) 4 was discovered as one of the main sources of ROS in glaucoma. However, the role and potential mechanisms of NOX4 in acute glaucoma have not been fully elucidated. Therefore, the current study aims to investigate the NOX4 inhibitor GLX351322 that targets NOX4 inhibition in acute ocular hypertension (AOH)-induced retinal ischemia/hypoxia injury in mice. Herein, NOX4 was highly expressed in AOH retinas, particularly the retinal ganglion cell layer (GCL). Importantly, the NOX4 inhibitor GLX351322 reduced ROS overproduction, inhibited inflammatory factor release, suppressed glial cell activation and hyperplasia, inhibited leukocyte infiltration, reduced retinal cell senescence and apoptosis in damaged areas, reduced retinal degeneration and improved retinal function. This neuroprotective effect is at least partially associated with mediated redox-sensitive factor (HIF-1α, NF-κB, and MAPKs) pathways by NOX4-derived ROS overproduction. These results suggest that inhibition of NOX4 with GLX351322 attenuated AOH-induced retinal inflammation, cellular senescence, and apoptosis by inhibiting the activation of the redox-sensitive factor pathway mediated by ROS overproduction, thereby protecting retinal structure and function. Targeted inhibition of NOX4 is expected to be a new idea in the treatment of acute glaucoma.

A state-of-the-art review on miRNA in prevention and treatment of Alzheimers disease

Alzheimer's disease (AD) is a multifactorial and heterogenic disorder. MiRNA is a class of non-coding RNAs with 19-22 nucleotides in length that can regulate the expression of target genes in the post-transcriptional level. It has been found that the miRNAome in AD patients is significantly altered in brain tissues, cerebrospinal fluid and blood circulation, as compared to healthy subjects. Experimental studies have suggested that expression changes in miRNA could drive AD onset and development via different mechanisms. Therefore, targeting miRNA expression to regulate the key genes involved in AD progression is anticipated to be a promising approach for AD prevention and treatment. Rodent AD models have demonstrated that targeting miRNAs could block biogenesis and toxicity of amyloid β, inhibit the production and hyper-phosphorylation of τ protein, prevent neuronal apoptosis and promote neurogenesis, maintain neural synaptic and calcium homeostasis, as well as mitigate neuroinflammation mediated by microglia. In addition, animal and human studies support the view that miRNAs are critical players contributing to the beneficial effects of cell therapy and lifestyle intervention to AD. This article reviews the most recent advances in the roles, mechanisms and applications of targeting miRNA in AD prevention and treatment based on rodent AD models and human intervention studies. The potential opportunities and challenges in clinical application of targeting miRNA for AD patients are also discussed.

MiR-204-3p overexpression inhibits gastric carcinoma cell proliferation by inhibiting the MAPK pathway and RIP1/MLK1 necroptosis pathway to promote apoptosis

BACKGROUND

Gastric carcinoma (GC) is the third most frequent cause of cancer-related death, highlighting the pressing need for novel clinical treatment options. In this regard, microRNAs (miRNAs) have emerged as a promising therapeutic strategy. Studies have shown that miRNAs can regulate related signaling pathways, acting as tumor suppressors or tumor promoters.

AIM

To explore the effect of miR-204-3p on GC cells.

METHODS

We measured the expression levels of miR-204-3p in GC cells using quantitative real-time polymerase chain reaction, followed by the delivery of miR-204-3p overexpression and miR-204-3p knockdown vectors into GC cells. CCK-8 was used to detect the effect of miR-204-3p on the proliferation of GC cells, and the colony formation ability of GC cells was detected by the clonal formation assay. The effects of miR-204-3p on GC cell cycle and apoptosis were detected by flow cytometry. The BABL/c nude mouse subcutaneous tumor model using MKN-45 cells was constructed to verify the effect of miR-204-3p on the tumorigenicity of GC cells. Furthermore, the study investigated the effects of miR-204-3p on various proteins related to the MAPK signaling pathway, necroptosis signaling pathway and apoptosis signaling pathway on GC cells using Western blot techniques.

RESULTS

Firstly, we found that the expression of miR-204-3p in GC was low. When treated with the lentivirus overexpression vector, miR-204-3p expression significantly increased, but the lentivirus knockout vector had no significant effect on miR-204-3p. In vitro experiments confirmed that miR-204-3p overexpression inhibited GC cell viability, promoted cell apoptosis, blocked the cell cycle, and inhibited colony formation ability. In vivo animal experiments confirmed that miR-204-3p overexpression inhibited subcutaneous tumorigenesis ability in BABL/c nude mice. Simultaneously, our results verified that miR-204-3p overexpression can inhibit GC cell proliferation by inhibiting protein expression levels of KRAS and p-ERK1/2 in the MAPK pathway, as well as inhibiting protein expression levels of p-RIP1 and p-MLK1 in the necroptosis pathway to promote the BCL-2/BAX/Caspase-3 apoptosis pathway.

CONCLUSION

MiR-204-3p overexpression inhibited GC cell proliferation by inhibiting the MAPK pathway and necroptosis pathway to promote apoptosis of GC cells. Thus, miR-204-3p may represent a new potential therapeutic target for GC.

Absent in melanoma 2 mediates aging-related cognitive dysfunction by acting on complement-dependent microglial phagocytosis

Pattern separation (PS) dysfunction is a type of cognitive impairment that presents early during the aging process, and this deficit has been attributed to structural and functional alterations in the dentate gyrus (DG) of the hippocampus. Absent in melanoma 2 (AIM2) is an essential component of the inflammasome. However, whether AIM2 plays a role in aging-associated cognitive dysfunction remains unclear. Here, we found that PS function was impaired in aging mice and was accompanied by marked synaptic loss and increased expression of AIM2 in the DG. Subsequently, we used an AIM2 overexpression virus and mice with AIM2 deletion to investigate the role of AIM2 in regulating PS function and synaptic plasticity and the mechanisms involved. Our study revealed that AIM2 regulates microglial activation during synaptic pruning in the DG region via the complement pathway, leading to impaired synaptic plasticity and PS function in aging mice. These results suggest a critical role for AIM2 in regulating synaptic plasticity and PS function and provide a new direction for ameliorating aging-associated cognitive dysfunction.

Sennoside A restrains TRAF6 level to modulate ferroptosis, inflammation and cognitive impairment in aging mice with Alzheimer's Disease

BACKGROUND

Alzheimer's disease (AD) is a common neurodegenerative disease and a momentous cause of dementia in the elderly. Sennoside A (SA) is an anthraquinone compound and possesses decisive protective functions in various human diseases. The purpose of this research was to elucidate the protective effect of SA against AD and investigate its mechanism.

METHODS

Male APPswe/PS1dE9 (APP/PS1) transgenic mice with a C57BL/6J background were chosen as AD model. Age-matched nontransgenic littermates (C57BL/6 mice) were negative controls. SA's functions in AD in vivo were estimated by cognitive function analysis, Western blot, hematoxylin-eosin staining, TUNEL staining, Nissl staining, detection of Fe²⁺ levels, glutathione and malondialdehyde contents, and quantitative real-time PCR. Also, SA's functions in AD in LPS-induced BV2 cells were examined using Cell Counting Kit-8 assay, flow cytometry, quantitative real-time PCR, Western blot, enzyme-linked immunosorbent assay, and analysis of reactive oxygen species levels. Meanwhile, SA's mechanisms in AD were assessed by several molecular experiments.

RESULTS

Functionally, SA mitigated cognitive function, hippocampal neuronal apoptosis, ferroptosis, oxidative stress, and inflammation in AD mice. Furthermore, SA reduced BV2 cell apoptosis, ferroptosis, oxidative stress, and inflammation induced by LPS. Rescue assay revealed that SA abolished the high expressions of TRAF6 and p-P65 (NF-κB pathway-related proteins) induced by AD, and this impact was reversed after TRAF6 overexpression. Conversely, this impact was further enhanced after TRAF6 knockdown.

CONCLUSIONS

SA relieved ferroptosis, inflammation and cognitive impairment in aging mice with AD through decreasing TRAF6.

Inhibition of hippocampal cyclin-dependent kinase 5 activity ameliorates learning and memory dysfunction in a mouse model of bronchopulmonary dysplasia

AIMS

Oxygen therapy plays a vital role in the development of bronchopulmonary dysplasia (BPD), which is the independent risk factor for neurodevelopment deficits in premature infants. However, the effect of hippocampal cyclin-dependent kinase 5 (CDK5) on BPD-associated neurodevelopment deficits is not fully understood.

METHODS

Mice were placed in a hyperoxia chamber from postnatal Day 1 to Day 7. Hematoxylin and eosin staining was used to evaluate the lung histomorphological characteristics. Learning and memory functions of mice were detected by Morris water maze. TUNEL staining was applied to measure the number of apoptotic cells. The expression of CDK5, apoptosis-related protein, and neuroplasticity-related proteins were analyzed by Western blot. Golgi staining was used to assess the structure of dendritic spines.

RESULTS

Hyperoxia-induced BPD mice showed a long-term learning and memory dysfunction, more severe neuronal apoptosis, and a decline of synaptic plasticity. Inhibition of CDK5 overactivation ameliorated cognitive deficits, neuronal apoptosis, and synaptic plasticity disorders in BPD mice.

CONCLUSIONS

This study first found a vital role of CDK5 in BPD-associated neurodevelopmental disorders. Inhibition of CDK5 overexpression could effectively improve cognitive dysfunctions in BPD mice, which indicated that hippocampal CDK5 may be a new target for prevention and treatment in learning and memory dysfunction of BPD.

Optogenetic Stimulation of mPFC Alleviates White Matter Injury-Related Cognitive Decline after Chronic Ischemia through Adaptive Myelination

White matter injury (WMI), which reflects myelin loss, contributes to cognitive decline or dementia caused by cerebral vascular diseases. However, because pharmacological agents specifically for WMI are lacking, novel therapeutic strategies need to be explored. It is recently found that adaptive myelination is required for homeostatic control of brain functions. In this study, adaptive myelination-related strategies are applied to explore the treatment for ischemic WMI-related cognitive dysfunction. Here, bilateral carotid artery stenosis (BCAS) is used to model ischemic WMI-related cognitive impairment and uncover that optogenetic and chemogenetic activation of glutamatergic neurons in the medial prefrontal cortex (mPFC) promote the differentiation of oligodendrocyte precursor cells (OPCs) in the corpus callosum, leading to improvements in myelin repair and working memory. Mechanistically, these neuromodulatory techniques exert a therapeutic effect by inducing the secretion of Wnt2 from activated neuronal axons, which acts on oligodendrocyte precursor cells and drives oligodendrogenesis and myelination. Thus, this study suggests that neuromodulation is a promising strategy for directing myelin repair and cognitive recovery through adaptive myelination in the context of ischemic WMI.

MicroRNAs in the Regulation of NADPH Oxidases in Vascular Diabetic and Ischemic Pathologies: A Case for Alternate Inhibitory Strategies?

Since their discovery in the vasculature, different NADPH oxidase (NOX) isoforms have been associated with numerous complex vascular processes such as endothelial dysfunction, vascular inflammation, arterial remodeling, and dyslipidemia. In turn, these often underlie cardiovascular and metabolic pathologies including diabetes mellitus type II, cardiomyopathy, systemic and pulmonary hypertension and atherosclerosis. Increasing attention has been directed toward miRNA involvement in type II diabetes mellitus and its cardiovascular and metabolic co-morbidities in the search for predictive and stratifying biomarkers and therapeutic targets. Owing to the challenges of generating isoform-selective NOX inhibitors (NOXi), the development of specific NOXis suitable for therapeutic purposes has been hindered. In that vein, differential regulation of specific NOX isoforms by a particular miRNA or combina-tion thereof could at some point become a reasonable approach for therapeutic targeting under some circumstances. Whereas administration of miRNAs chronically, or even acutely, to patients poses its own set of difficulties, miRNA-mediated regulation of NOXs in the vasculature is worth surveying. In this review, a distinct focus on the role of miRNAs in the regulation of NOXs was made in the context of type II diabetes mellitus and ischemic injury models.

[Effect of inhibiting miR-204 expression on the learning and memory abilities of neonatal rats with intrauterine growth restriction and related mechanism]

OBJECTIVES

To investigate the effect of inhibiting miR-204 expression on the learning and memory abilities of neonatal rats with intrauterine growth restriction (IUGR) and related mechanism.

METHODS

A rat model of IUGR was prepared by low-protein diet. The 3-day-old IUGR rats were divided into three groups: model, miRNA antagonist control and miR-204 antagonist, with 10 rats in each group. Ten normal neonatal rats served as the control group. Morris water maze test was used to measure the learning and memory abilities of the rats. Quantitative real-time PCR was used to measure the mRNA expression levels of miR-204 and brain-derived neurotrophic factor (BDNF) in the hippocampus. Nissl staining and TUNEL staining were used to observe the number of Nissl bodies and the apoptosis of cells in the hippocampus. Western blot was used to measure the expression levels of BDNF/TrkB signaling pathway-related proteins in the hippocampus.

RESULTS

Compared with the control group, the model group had a significant increase in the escape latency and a significant reduction in the number of platform crossings (P<0.001). The model group also had significant increases in the apoptosis rate of cells and the expression level of miR-204 in hippocampal tissue (P<0.001), while the number of Nissl bodies, the mRNA expression level of BDNF, and the protein expression levels of BDNF, p-TrkB, and p-CREB in the model group were significantly reduced compared with the control group (P<0.001). After inhibition of the expression of miR-204, the number of Nissl bodies, the mRNA expression level of BDNF, and the protein expression levels of BDNF, p-TrkB, and p-CREB significantly increased, while the cell apoptosis rate and the expression level of miR-204 in the hippocampus significantly decreased. The escape latency was also reduced, while the number of platform crossings increased after inhibition of the expression of miR-204 (P<0.001).

CONCLUSIONS

Inhibiting miR-204 can improve the learning and memory functions of neonatal rats with IUGR, possibly by targeted activation of the BDNF/TrkB signaling pathway.

miR-204-3p downregulates KRT16 and promotes corneal repair in tree shrew fungal keratitis model

OBJECTIVES

Corneal repair is critical for the treatment and recovery of corneal injuries. However, the molecular mechanism underlying corneal repair remains unclear.

METHODS

A tree shrew model of corneal fungal infection was established by injecting Fusarium solani into the corneal stroma to study the role of miR-204-3p in repairing corneal injury induced by fungal keratitis and to explore the potential mechanisms underlying the repair process.

RESULTS

miR-204-3p expression was significantly downregulated, while KRT16 expression was significantly upregulated after F. solani infection in the cornea of tree shrews. Moreover, miR-204-3p injection promoted corneal injury repair post-infection, potentially by downregulating KRT16 expression. Results of a luciferase reporter gene assay showed that miR-204-3p had a targeted relationship with KRT16. KRT16 protein expression levels decreased after miR-204-3p injection into the cornea with fungal keratitis, reducing the degree of corneal injury.

CONCLUSIONS

In this study, we report for the first time that miR-204-3p and KRT16 influence the repair of corneal injury. In addition, their effects on the repair of corneal injury were studied in a tree shrew model, providing an experimental basis for the study of pathogenesis of human fungal keratitis.

Free radical biology in neurological manifestations: mechanisms to therapeutics interventions

Recent advancements and growing attention about free radicals (ROS) and redox signaling enable the scientific fraternity to consider their involvement in the pathophysiology of inflammatory diseases, metabolic disorders, and neurological defects. Free radicals increase the concentration of reactive oxygen and nitrogen species in the biological system through different endogenous sources and thus increased the overall oxidative stress. An increase in oxidative stress causes cell death through different signaling mechanisms such as mitochondrial impairment, cell-cycle arrest, DNA damage response, inflammation, negative regulation of protein, and lipid peroxidation. Thus, an appropriate balance between free radicals and antioxidants becomes crucial to maintain physiological function. Since the 1brain requires high oxygen for its functioning, it is highly vulnerable to free radical generation and enhanced ROS in the brain adversely affects axonal regeneration and synaptic plasticity, which results in neuronal cell death. In addition, increased ROS in the brain alters various signaling pathways such as apoptosis, autophagy, inflammation and microglial activation, DNA damage response, and cell-cycle arrest, leading to memory and learning defects. Mounting evidence suggests the potential involvement of micro-RNAs, circular-RNAs, natural and dietary compounds, synthetic inhibitors, and heat-shock proteins as therapeutic agents to combat neurological diseases. Herein, we explain the mechanism of free radical generation and its role in mitochondrial, protein, and lipid peroxidation biology. Further, we discuss the negative role of free radicals in synaptic plasticity and axonal regeneration through the modulation of various signaling molecules and also in the involvement of free radicals in various neurological diseases and their potential therapeutic approaches. The primary cause of free radical generation is drug overdosing, industrial air pollution, toxic heavy metals, ionizing radiation, smoking, alcohol, pesticides, and ultraviolet radiation. Excessive generation of free radicals inside the cell R1Q1 increases reactive oxygen and nitrogen species, which causes oxidative damage. An increase in oxidative damage alters different cellular pathways and processes such as mitochondrial impairment, DNA damage response, cell cycle arrest, and inflammatory response, leading to pathogenesis and progression of neurodegenerative disease other neurological defects.

SIRT7 Deficiency Protects against Aβ42-Induced Apoptosis through the Regulation of NOX4-Derived Reactive Oxygen Species Production in SH-SY5Y Cells

Alzheimer's disease (AD) is an age-related neurodegenerative disease that is characterized by irreversible memory loss and cognitive decline. The deposition of amyloid-β (Aβ), especially aggregation-prone Aβ₄₂, is considered to be an early event preceding neurodegeneration in AD. Sirtuins (SIRT1-7 in mammals) are nicotinamide adenine dinucleotide-dependent lysine deacetylases/deacylases, and several sirtuins play important roles in AD. However, the involvement of SIRT7 in AD pathogenesis is not known. Here, we demonstrate that SIRT7 mRNA expression is increased in the cortex, entorhinal cortex, and prefrontal cortex of AD patients. We also found that Aβ₄₂ treatment rapidly increased NADPH oxidase 4 (NOX4) expression at the post-transcriptional level, and induced reactive oxygen species (ROS) production and apoptosis in neuronal SH-SY5Y cells. In contrast, SIRT7 knockdown inhibited Aβ₄₂-induced ROS production and apoptosis by suppressing the upregulation of NOX4. Collectively, these findings suggest that the inhibition of SIRT7 may play a beneficial role in AD pathogenesis through the regulation of ROS production.

Dioscin alleviates Alzheimer's disease through regulating RAGE/NOX4 mediated oxidative stress and inflammation

Alzheimer's disease (AD) is a neurodegenerative disease with amyloid beta (Aβ) deposition and intracellular neurofibrillary tangles (NFTs) as its characteristic pathological changes. Ameliorating oxidative stress and inflammation has become a new trend in the prevention and treatment of AD. Dioscin, a natural steroidal saponin which exists in Dioscoreae nipponicae rhizomes, displays various pharmacological activities, but its role in Alzheimer's disease (AD) is still unknown. In the present work, effect of dioscin on AD was evaluated in injured SH-SY5Y cells induced by H₂O₂ and C57BL/6 mice with AD challenged with AlCl₃ combined with D-galactose. Results showed that dioscin obviously increased cell viability and decreased reactive oxygen species (ROS) level in injured SH-SY5Y cells. In vivo, dioscin obviously improved the spatial learning and memory abilities as well as gait and interlimb coordination disorders of mice with AD. Moreover, dioscin distinctly restored the levels of malondialdehyde (MDA), superoxide dismutase (SOD), amyloid beta 42 (Aβ₄₂), acetylcholine (ACh) and acetylcholinesterase (AChE) of mice, and reversed the histopathological changes of brain tissue. Mechanism studies revealed that dioscin markedly down-regulated the expression levels of RAGE and NOX4. Subsequently, dioscin markedly up-regulated the expression levels of Nrf2 and HO-1 related to oxidative stress, and down-regulated the levels of p-NF-κB(p-p65)/NF-κB(p65), AP-1 and inflammatory factors involved in inflammatory pathway. RAGE siRNAs transfection further clarified that the pharmacological activity of dioscin in AD was achieved by regulating RAGE/NOX4 pathway. In conclusion, dioscin showed excellent anti-AD effect by adjusting RAGE/NOX4-mediated oxidative stress and inflammation, which provided the basis for the further research and development against AD.

Identification of miRNA–mRNA Pairs in the Alzheimer’s Disease Expression Profile and Explore the Effect of miR-26a-5p/PTGS2 on Amyloid-β Induced Neurotoxicity in Alzheimer’s Disease Cell Model

Alzheimer’s disease (AD) is a progressive neurodegenerative disease and the most common type of dementia. MicroRNAs (miRNAs) have been extensively studied in many diseases, including AD. To identify the AD-specific differentially expressed miRNAs and mRNAs, we used bioinformatics analysis to study candidate miRNA–mRNA pairs involved in the pathogenesis of AD. These miRNA–mRNAs may serve as promising biomarkers for early diagnosis or targeted therapy of AD patients. In this study, based on the AD mRNA and miRNA expression profile data in Gene Expression Omnibus (GEO), through differential expression analysis, functional annotation and enrichment analysis, weighted gene co-expression network analysis, miRNA–mRNA regulatory network, protein–protein interaction network, receiver operator characteristic and Least absolute shrinkage and selection operator (LASSO) regression and other analysis, we screened the key miRNA–mRNA in the progress of AD: miR-26a-5p/PTGS2. Dual-luciferase and qPCR experiments confirmed that PTGS2 is a direct target gene of miR-26a-5p. The expression of miR-26a-5p in the peripheral blood of AD patients and AD model cells (SH-SY5Y cells treated with Aβ_25–35) was up-regulated, and the expression of PTGS2 was down-regulated. Functional gain -loss experiments confirmed that PTGS2 protects AD model cells from damage by inhibiting proliferation and migration. However, the expression of miR-26a-5p promotes the proliferation of AD model cells. It is further found that PTGS2 is involved in the regulation of miR-26a-5p and can reverse the effect of miR-26a-5p on the proliferation of AD model cells. In addition, through network pharmacology, qPCR and CCK-8, we found that baicalein may affect the progression of AD by regulating the expression of PTGS2. Therefore, PTGS2 can be used as a target for AD research, and miR-26a-5p/PTGS2 can be used as an axis of action to study the pathogenesis of AD.

MicroRNA-182-5p Attenuates Asthmatic Airway Inflammation by Targeting NOX4

Bronchial asthma is characterized by chronic airway inflammation, airway hyperresponsiveness, and airway remodeling. MicroRNA (miRNA) has recently been implicated in the pathogenesis of asthma. However, the mechanisms of different miRNAs in asthma are complicated, and the mechanism of miRNA-182-5p in asthma is still unclear. Here, we aim to explore the mechanism of miRNA182-5p in asthma-related airway inflammation. Ovalbumin (OVA)-induced asthma model was established. MiRNA Microarray Analysis was performed to analyze the differentially expressed miRNAs in the asthma model. We found that the expression of miRNA-182-5p was significantly decreased in OVA-induced asthma. In vitro, IL-13 stimulation of BEAS-2B cells resulted in a significant up-regulation of NOX4 (nicotinamide adenine dinucleotide phosphate oxidase 4), accompanied by mitochondrial damage-induced apoptosis, NLRP3 (NOD-like receptor family pyrin domain-containing 3)/IL-1β activation, and reduced miRNA-182-5p. In contrast, overexpression of miRNA-182-5p significantly inhibited epithelial cell apoptosis and NLRP3/IL-1β activation. In addition, we found that miRNA-182-5p could bind to the 3’ untranscripted region of NOX4 mRNA and inhibit epithelial cell inflammation by reducing oxidative stress and mitochondrial damage. In vivo, miRNA-182-5p agomir treatment significantly reduced the percentage of eosinophils in bronchoalveolar lavage fluid, and down-regulated Th2 inflammatory factors, including IL-4, IL-5, and OVA induced IL-13. Meanwhile, miRNA-182-5p agomir reduced the peribronchial inflammatory cell infiltration, goblet cell proliferation and collagen deposition. In summary, targeting miRNA-182-5p may provide a new strategy for the treatment of asthma.

MicroRNA Alteration, Application as Biomarkers, and Therapeutic Approaches in Neurodegenerative Diseases

MicroRNAs (miRNAs) are essential post-transcriptional gene regulators involved in various neuronal and non-neuronal cell functions and play a key role in pathological conditions. Numerous studies have demonstrated that miRNAs are dysregulated in major neurodegenerative diseases, such as Alzheimer’s disease, Parkinson’s disease, multiple sclerosis, amyotrophic lateral sclerosis, or Huntington’s disease. Hence, in the present work, we constructed a comprehensive overview of individual microRNA alterations in various models of the above neurodegenerative diseases. We also provided evidence of miRNAs as promising biomarkers for prognostic and diagnostic approaches. In addition, we summarized data from the literature about miRNA-based therapeutic applications via inhibiting or promoting miRNA expression. We finally identified the overlapping miRNA signature across the diseases, including miR-128, miR-140-5p, miR-206, miR-326, and miR-155, associated with multiple etiological cellular mechanisms. However, it remains to be established whether and to what extent miRNA-based therapies could be safely exploited in the future as effective symptomatic or disease-modifying approaches in the different human neurodegenerative disorders.

LncRNA GAS5 regulates migration and epithelial-to-mesenchymal transition in lens epithelial cells via the miR-204-3p/TGFBR1 axis

Diabetic cataract (DC) is a major ocular complication secondary to diabetes mellitus. The epithelial-mesenchymal transition (EMT) of lens epithelial cells (LECs) is an important event in DC progression. Long non-coding RNAs (lncRNAs) and microRNAs are involved in various biological processes and disorders. The aim of this study was to investigate the roles of lncRNA growth arrest-specific transcript 5 (GAS5) and microRNA-204-3p (miR-204-3p) deregulation in the pathogenic mechanism of high glucose (HG)-stimulated LECs. The results show that GAS5 was up-regulated, whereas miR-204-3p was down-regulated in anterior lens capsule tissues of DC patients and in HG-treated LECs compared to their controls, respectively. Functional experiments suggest that the lentivirus-mediated depletion of GAS5, as well as overexpression of miR-204-3p, suppressed migration and EMT in HG-treated LECs. Further mechanistic studies revealed that lncRNA GAS5/miR-204-3p/type 1 receptor of transforming growth factor-beta (TGFBR1) has a regulatory role in the process. Collectively, we demonstrated that dysregulation of GAS5 affects lens epithelial cell migration and EMT under HG conditions via the miR-204-3p/TGFBR1 axis. The current findings may provide new insights into the molecular mechanisms of DC development.

Hsa_circ_0134111 promotes intervertebral disc degeneration via sponging miR-578

Intervertebral disc degeneration (IDD) is a chronic degenerative and age-dependent process characterized by aberrant apoptosis, proliferation, synthesis, and catabolism of the extracellular matrix of the nucleus pulposus (NP) cells. Recently, studies showed that circular RNAs play important roles in the development of many diseases. However, the role of circRNAs in IDD development remains unknown. We showed that circ_0134111 level was overexpressed in IDD tissue samples as compar-ed to control tissues. The upregulation of circ_0134111 was more drastic in the moderate and severe IDD cases than in those with mild IDD. In addition, we showed that interleukin-1β and tumor necrosis factor-α exposure significantly enhanced circ_0134111 expression in NP cells. Furthermore, ectopic expression of circ_0134111 induced proliferation, pro-inflammatory cytokine secretion, and ECM degradation in the NP cells. We also showed that circ_0134111 directly interacted with microRNA (miR)-578 in NP cells where elevated expression of circ_0134111 enhanced the ADAMTS-5 and MMP-9 expression. Moreover, miR-578 expression was significantly decreased in IDD patients and the miR-578 expression was negatively correlated with circ_0134111 expression in the IDD samples. Interleukin-1β and tumor necrosis factor-α exposure significantly decreased miR-578 levels in NP cells, in which ectopic miR-578 expression inhibited cell growth, pro-inflammatory cytokine expression, and ECM degradation. Finally, we showed that circ_0134111 overexpression induced the IDD-related phenotypic changes through inhibiting miR-578. These data suggested that circ_0134111 could promote the progression of IDD through enhancing aberrant NP cell growth, inflammation, and ECM degradation partly via regulating miR-578.

Implication of type 4 NADPH oxidase (NOX4) in tauopathy

Aggregates of the microtubule-associated protein tau are a common marker of neurodegenerative diseases collectively termed as tauopathies, such as Alzheimer's disease (AD) and frontotemporal dementia. Therapeutic strategies based on tau have failed in late stage clinical trials, suggesting that tauopathy may be the consequence of upstream causal mechanisms. As increasing levels of reactive oxygen species (ROS) may trigger protein aggregation or modulate protein degradation and, we had previously shown that the ROS producing enzyme NADPH oxidase 4 (NOX4) is a major contributor to cellular autotoxicity, this study was designed to evaluate if NOX4 is implicated in tauopathy. Our results show that NOX4 is upregulated in patients with frontotemporal lobar degeneration and AD patients and, in a humanized mouse model of tauopathy induced by AVV-TauP301L brain delivery. Both, global knockout and neuronal knockdown of the Nox4 gene in mice, diminished the accumulation of pathological tau and positively modified established tauopathy by a mechanism that implicates modulation of the autophagy-lysosomal pathway (ALP) and, consequently, improving the macroautophagy flux. Moreover, neuronal-targeted NOX4 knockdown was sufficient to reduce neurotoxicity and prevent cognitive decline, even after induction of tauopathy, suggesting a direct and causal role for neuronal NOX4 in tauopathy. Thus, NOX4 is a previously unrecognized causative, mechanism-based target in tauopathies and blood-brain barrier permeable specific NOX4 inhibitors could have therapeutic potential even in established disease.

Mesenchymal stem cells transfected with anti-miRNA-204-3p inhibit acute rejection after heart transplantation by targeting C-X-C motif chemokine receptor 4 (CXCR4) in vitro

Background

Mesenchymal stem cells (MSCs) are a promising treatment for acute rejection (AR) after heart transplantation (HTx) owing to their immunomodulatory functions by promoting the transformation of macrophages from the M0 to M2 phenotype. However, it is undetermined whether surface expression of C-X-C motif chemokine receptor 4 (CXCR4) by MSCs influences macrophage polarization. In this study, we investigated the effects of MSCs on macrophages caused by CXCR4, and detected the underlying mechanism, which may contribute to improving HTx outcomes.

Methods

The MSCs were extracted from rat bone marrow and identified using flow cytometry. We subsequently observed the effects of CXCR4 and anti-miRNA-204-3p on cell proliferation and migration, and the effects on macrophage polarization. Dual luciferase reporter assay was used to explore whether miRNA-204-3p was an upstream microRNA (miRNA) of CXCR4. A series of rescue experiments were performed to further confirm the inhibitory effect of miRNA-204-3p on CXCR4.

Results

The results showed that CXCR4 could promote the proliferation and migration of MSCs. Furthermore, it facilitated MSC-mediated macrophage transformation from the M0 to M2 phenotype. In addition, miRNA-204-3p inhibited the function of CXCR4 of MSCs.

Conclusions

Regulated by miRNA-204-3p, CXCR4 could inhibit the progression of AR after HTx. This study provides a new insight of the treatment of AR after HTx.

MicroRNA Dysregulation in the Hippocampus of Rats with Noise-Induced Hearing Loss

Although hippocampal changes due to noise-induced hearing loss have been suggested, little is known about the miRNA levels due to these hippocampal changes. Three-week-old Sprague-Dawley rats were divided into noise and control groups (n = 20 per group). The noise group rats were exposed to white Gaussian noise (115 dB SPL, 4 hours per day) for three days. One day after noise exposure, the hippocampi of rats were harvested and miRNA expressions were analyzed using the Affymetrix miRNA 4.0 microarray (n = 6 per group). The predicted target genes of each miRNA were retrieved, and the pathways related to the predicted target genes were analyzed. miR-758-5p, miR-210-5p, miR-370-5p, miR-652-5p, miR-3544, miR-128-1-5p, miR-665, miR-188-5p, and miR-874-5p expression increased in the hippocampal tissue of the noise group compared to that in the control group. The overlapping predicted target genes included Bend4, Creb1, Adcy6, Creb5, Kcnj9, and Pten. The pathways related to these genes were the estrogen signaling pathway, vasopressin-regulated water reabsorption, thyroid hormone synthesis, aldosterone synthesis and secretion, insulin secretion, circadian entrainment, insulin resistance, cholinergic synapse, dopaminergic synapse, cGMP-PKG signaling pathway, cAMP signaling pathway, PI3K-Akt signaling pathway, TNF signaling pathway, and AMPK signaling pathway. miR-448-3p, miR204-5p, and miR-204-3p expression decreased in the hippocampal tissue of the noise group compared to that in the control group. The overlapping predicted target genes of these three miRNAs were Rps6kas, Nfactc3, Rictor, Spred1, Cdh4, Cdh6, Dvl3, and Rcyt1b. Pathway analysis suggested that the Wnt signaling pathway is related to Dvl3 and Nfactc3. Noise-induced hearing loss dysregulates miR-758-5p, miR210-5p, miR370-5p, miR-652-5p, miR-3544, miR-128-1-5p, miR-665, miR-188-5p, miR-874-5p, miR-448-3p, miR-204-5p, miR-204-3p, and miR-140-5p expression in the hippocampus. These miRNAs have been predicted to be associated with hormonal, inflammatory, and synaptic pathways.

Microglial lnc-U90926 facilitates neutrophil infiltration in ischemic stroke via MDH2/CXCL2 axis

Dysregulated long non-coding RNAs (lncRNAs) have been shown to contribute to the pathogenesis of ischemic stroke. However, the potential role of lncRNAs in post-stroke microglial activation remains largely unknown. Here, we uncovered that lncRNA-U90926 was significantly increased in microglia exposed to ischemia/reperfusion both in vivo and in vitro. In addition, adenovirus-associated virus (AAV)-mediated microglial U90926 silencing alleviated neurological deficits and reduced infarct volume in experimental stroke mice. Microglial U90926 knockdown could reduce the infiltration of neutrophils into ischemic lesion site, which might be attributed to the downregulation of C-X-C motif ligand 2 (CXCL2). Mechanistically, U90926 directly bound to malate dehydrogenase 2 (MDH2) and competitively inhibited the binding of MDH2 to the CXCL2 3' untranslated region (UTR), thus protecting against MDH2-mediated decay of CXCL2 mRNA. Taken together, our study demonstrated that microglial U90926 aggravated ischemic brain injury via facilitating neutrophil infiltration, suggesting that U90926 might be a potential biomarker and therapeutic target for ischemic stroke.

Implication of Nicotinamide Adenine Dinucleotide Phosphate (NADPH) Oxidase and Its Inhibitors in Alzheimer's Disease Murine Models

Alzheimer’s disease (AD) is one of the main human dementias around the world which is constantly increasing every year due to several factors (age, genetics, environment, etc.) and there are no prevention or treatment options to cure it. AD is characterized by memory loss associated with oxidative stress (OS) in brain cells (neurons, astrocytes, microglia, etc.). OS can be produced by amyloid beta (Aβ) protein aggregation and its interaction with metals, mitochondrial damage and alterations between antioxidants and oxidant enzymes such as nicotinamide adenine dinucleotide phosphate (NADPH) oxidase. NADPH oxidase produces reactive oxygen species (ROS) and it is overexpressed in AD, producing large amounts of superoxide anions and hydrogen peroxide which damage brain cells and the vasculature. In addition, it has been reported that NADPH oxidase causes an imbalance of pH which could also influence in the amyloid beta (Aβ) production. Therefore, NADPH oxidase had been proposed as a therapeutic target in AD. However, there are no drugs for AD treatment such as an NADPH oxidase inhibitor despite great efforts made to stabilize the ROS production using antioxidant molecules. So, in this work, we will focus our attention on NADPH oxidase (NOX2 and NOX4) in AD as well as in AD models and later discuss the use of NADPH oxidase inhibitor compounds in AD.

MicroRNA-126a-5p Exerts Neuroprotective Effects on Ischemic Stroke via Targeting NADPH Oxidase 2

BACKGROUND

Ischemic stroke is a destructive cerebrovascular disorder related to oxidative stress; NOX2 is a major source for ROS production; and miR-126a-5p is involved in several diseases, such as abdominal aortic aneurysm. We investigated the role of miR-126a-5p in regulating NOX2 in ischemic stroke.

METHODS

MiR-126a-5p and NOX2 were examined in the brains of rats subjected to cerebral ischemia/reperfusion (I/R) by RT-PCR and Western blot. MiR-126a-5p agomir was delivered to examine the effects of miR-126a-5p on I/R injury. The neurological deficit, infarct volume, and brain water content were evaluated. NOX activity, ROS production, and MDA and SOD levels were detected to assess oxidative stress. H&E staining was used to examine cell state. Apoptosis was evaluated by TUNEL, caspase-3 activity, and cleaved-caspase-3 protein level. The relationship between miR-126a-5p and NOX2 was analyzed by bioinformatics and luciferase reporter assay. MiR-126a-5p mimic, miR-126a-5p inhibitor, or pcDNA-NOX2 were transfected in SH-SY5Y cells to further assess the effects of miR-126a-5p on OGD/R-induced cells injury.

RESULTS

NOX2 was upregulated and miR-126a-5p was down-regulated in the brains of I/R rats. MiR-126a-5p agomir obviously reduced the neurological deficit, infarct volume, brain water content, oxidative stress, and apoptosis in I/R rats. MiR-126a-5p targeted NOX2 directly and regulated NOX2 negatively. Moreover, miR-126a-5p mimic elevated cell viability and inhibited oxidative stress and apoptosis in OGD/R-treated SH-SY5Y cells, while miR-126a-5p inhibitor had the opposite effects. NOX2 overexpression antagonized the protective effects of miR-126a-5p mimic on OGD/R-induced cell injury.

CONCLUSION

MiR-126a-5p is a novel potential target for ischemic stroke therapy due to its protection against cerebral I/R injury via directly targeting NOX2.