Inflammation in neurodegenerative diseases--an update

Microglia have limited influence on early prion pathogenesis, clearance, or replication

Microglia (MG) are critical to host defense during prion infection, but the mechanism(s) of this neuroprotection are poorly understood. To better examine the influence of MG during prion infection, we reduced MG in the brains of C57BL/10 mice using PLX5622 and assessed prion clearance and replication using multiple approaches that included bioassay, immunohistochemistry, and Real-Time Quaking Inducted Conversion (RT-QuIC). We also utilized a strategy of intermittent PLX5622 treatments to reduce MG and allow MG repopulation to test whether new MG could alter prion disease progress. Lastly, we investigated the influence of MG using tga20 mice, a rapid prion model that accumulates fewer pathological features and less PrPres in the infected brain. In C57BL/10 mice we found that MG were excluded from the inoculation site early after infection, but Iba1 positive infiltrating monocytes/macrophage were present. Reducing MG in the brain prior to prion inoculation did not increase susceptibility to prion infection. Short intermittent treatments with PLX5622 in prion infected C57BL/10 mice after 80 dpi were unsuccessful at altering the MG population, gliosis, or survival. Additionally, MG depletion using PLX5622 in tga20 mice had only a minor impact on prion pathogenesis, indicating that the presence of MG might be less important in this fast model with less prion accumulation. In contrast to the benefits of MG against prion disease in late stages of disease, our current experiments suggest MG do not play a role in early prion pathogenesis, clearance, or replication.

Anti-inflammatory, cytotoxicity and antilipidemic properties: novel bioactivities of true cinnamon (Cinnamomum zeylanicum Blume) leaf

Background

The leaf of Ceylon cinnamon (true cinnamon) is traditionally claimed for a variety of health benefits. However, reported scientific information is scanty and needs urgent attention for value addition.

Methods

Ethanolic (95%) and Dichloromethane:Methanol (DM, 1:1 v/v) leaf extracts of Ceylon cinnamon were evaluated for a range of medically important bioactivities namely anti-inflammatory [nitric oxide scavenging activity (NOSA), superoxide scavenging activity (SCA), COX1 and COX2 inhibition], growth inhibition & cytotoxicity against MCF7, HePG2 and AN3CA carcinoma cell lines, glutathionase-S-transferase (GST) inhibition and antilipidemic (anti-HMG-CoA reductase, anti-lipase, anti-cholesterol esterase, and cholesterol micellization inhibition) properties in vitro (n = 3). Further, a range of bioactive compounds in both leaf extracts was also quantified (n = 3).

Results

Both leaf extracts had all the investigated bioactive compounds and possessed moderately potent bioactivities compared to the reference drugs used in the study. Ethanolic leaf extract (ELE) exhibited the highest activities (IC_50: μg/mL) for NOSA (40.26 ± 0.52), SCA (696.24 ± 40.02), cholesterol esterase inhibition (110.19 ± 1.55), cholesterol micellization inhibition (616.69 ± 7.09), GST inhibition (403.78 ± 2.70) and growth inhibition (GI₅₀: 144.84 ± 1.59-269.00 ± 0.51) & cytotoxicity (LC₅₀: 355.44 ± 9.38-717.71 ± 23.69) against studied cancer cell lines. In contrast, COX1 & COX2 (IC_50: 6.62 ± 0.85 and 44.91 ± 3.06 μg/mL) and HMG-CoA reductase & lipase inhibitory activities (36.72 ± 4.74 and 19.71 ± 0.97% inhibition at 200 and 600 μg/mL) were highest in DM extract. ELE also showed the highest quantities (0.81 ± 0.06-104.38 ± 1.79) of tested compounds (mg/g extract) where eugenol was the highest and gallic acid was the lowest among quantified.

Conclusion

Both leaf extracts of Ceylon cinnamon had all the tested bioactive compounds and possess all the investigated bioactivities. This is the 1st study to report all the investigated bioactivities of the leaf of Ceylon Cinnamon.

A change of PD-1/PD-L1 expression on peripheral T cell subsets correlates with the different stages of Alzheimer's Disease

Background

Immune checkpoints are a set of costimulatory and inhibitory molecules that maintain self-tolerance and regulate immune homeostasis. The expression of immune checkpoints on T cells in malignancy, chronic inflammation, and neurodegenerative diseases has gained increasing attention.

Results

To characterize immune checkpoints in neurodegenerative diseases, we aimed to examine the expression of the immune checkpoint PD-1/PD-L1 in peripheral T cells in different Alzheimer’s disease (AD) patients. To achieve this aim, sixteen AD patients and sixteen age-matched healthy volunteers were enrolled to analyze their CD3⁺ T cells, CD3⁺CD56⁺ (neural cell adhesion molecule, NCAM) T cells, CD4⁺/CD8⁺ T cells, and CD4⁺/CD8⁺CD25⁺ (interleukin-2 receptor alpha, IL-2RA) T cells in this study. The expression of PD-1 on T cells was similar between the AD patients and healthy volunteers, but increased expression of PD-L1 on CD3⁺CD56⁺ T cells (natural killer T cells, NKT-like), CD4⁺ T cells (helper T cells, Th), CD4⁺CD25⁺ T cells, and CD8⁺ T cells (cytotoxic T lymphocytes, CTL) was detected in the AD patients. In addition, we found negative correlations between the AD patients’ cognitive performance and both CD8⁺ T cells and CD8⁺CD25⁺ T cells. To identify CD8⁺ T-cell phenotypic and functional characteristic differences between the healthy volunteers and AD patients in different stages, a machine learning algorithm, t-distributed stochastic neighbor embedding (t-SNE), was implemented. Using t-SNE enabled the above high-dimensional data to be visualized and better analyzed. The t-SNE analysis demonstrated that the cellular sizes and densities of PD-1/PD-L1 on CD8⁺ T cells differed among the healthy, mild AD, and moderate AD subjects.

Conclusions

Our results suggest that changes in PD-1/PD-L1-expressing T cells in AD patients’ peripheral blood could be a potential biomarker for monitoring disease and shed light on the AD disease mechanism. Moreover, these findings indicate that PD-1/PD-L1 blockade treatment could be a novel choice to slow AD disease deterioration.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13578-022-00897-1.

Multi-Target Mechanisms of Phytochemicals in Alzheimer’s Disease: Effects on Oxidative Stress, Neuroinflammation and Protein Aggregation

Alzheimer’s disease (AD) is a neurodegenerative disease characterized by a tangle-shaped accumulation of beta-amyloid peptide fragments and Tau protein in brain neurons. The pathophysiological mechanism involves the presence of Aβ-amyloid peptide, Tau protein, oxidative stress, and an exacerbated neuro-inflammatory response. This review aims to offer an updated compendium of the most recent and promising advances in AD treatment through the administration of phytochemicals. The literature survey was carried out by electronic search in the following specialized databases PubMed/Medline, Embase, TRIP database, Google Scholar, Wiley, and Web of Science regarding published works that included molecular mechanisms and signaling pathways targeted by phytochemicals in various experimental models of Alzheimer’s disease in vitro and in vivo. The results of the studies showed that the use of phytochemicals against AD has gained relevance due to their antioxidant, anti-neuroinflammatory, anti-amyloid, and anti-hyperphosphorylation properties of Tau protein. Some bioactive compounds from plants have been shown to have the ability to prevent and stop the progression of Alzheimer’s.

The Significance of NLRP Inflammasome in Neuropsychiatric Disorders

The NLRP inflammasome is a multi-protein complex which mainly consists of the nucleotide-binding oligomerization domain, leucine-rich repeat, and pyrin domain. Its activation is linked to microglial-mediated neuroinflammation and partial neuronal degeneration. Many neuropsychiatric illnesses have increased inflammatory responses as both a primary cause and a defining feature. The NLRP inflammasome inhibition delays the progression and alleviates the deteriorating effects of neuroinflammation on several neuropsychiatric disorders. Evidence on the central effects of the NLRP inflammasome potentially provides the scientific base of a promising drug target for the treatment of neuropsychiatric disorders. This review elucidates the classification, composition, and functions of the NLRP inflammasomes. It also explores the underlying mechanisms of NLRP inflammasome activation and its divergent role in neuropsychiatric disorders, including Alzheimer’s disease, Huntington’s disease, Parkinson’s disease, depression, drug use disorders, and anxiety. Furthermore, we explore the treatment potential of the NLRP inflammasome inhibitors against these disorders.

The potential use of tetracyclines in neurodegenerative diseases and the role of nano-based drug delivery systems

Neurodegenerative diseases are still a challenge for effective treatments. The high cost of approved drugs, severity of side effects, injection site pain, and restrictions on drug delivery to the Central Nervous System (CNS) can overshadow the management of these diseases. Due to the chronic and progressive evolution of neurodegenerative disorders and since there is still no cure for them, new therapeutic strategies such as the combination of several drugs or the use of existing drugs with new therapeutic applications are valuable strategies. Tetracyclines are traditionally classified as antibiotics. However, in this class of drugs, doxycycline and minocycline exhibit also anti-inflammatory effects by inhibiting microglia/macrophages. Hence, they have been studied as potential agents for the treatment of neurodegenerative diseases. The results of in vitro and in vivo studies confirm the effective role of these two drugs as anti-inflammatory agents in experimentally induced models of neurodegenerative diseases. In clinical studies, satisfactory results have been obtained in Multiple sclerosis (MS) but not yet in other disorders such as Alzheimer's disease (AD), Parkinson's disease (PD), or Amyotrophic lateral sclerosis (ALS). In recent years, researchers have developed and evaluated nanoparticulate drug delivery systems to improve the clinical efficacy of these two tetracyclines for their potential application in neurodegenerative diseases. This study reviews the neuroprotective roles of minocycline and doxycycline in four of the main neurodegenerative disorders: AD, PD, ALS and MS. Moreover, the potential applications of nanoparticulate delivery systems developed for both tetracyclines are also reviewed.

Fibrinogen in Alzheimer's Disease, Parkinson's Disease and Lewy Body Dementia: A Mendelian Randomization Study

Fibrinogen is reportedly associated with neurodegenerative diseases (NDs), but the underlying causality remains controversial. Using Mendelian randomization (MR), this study aimed to assess the causal association between fibrinogen and Alzheimer’s disease (AD), Parkinson’s disease (PD), and Lewy body dementia (LBD). Genetic variants associated with fibrinogen and γ-fibrinogen were selected and used as instrumental variables. The effect estimates of the main analysis were obtained by inverse-variance weighting (IVW), complemented by sensitivity analyses to verify model assumptions, and multivariable MR was conducted to control for potential pleiotropic effect. Two-step MR was performed to assess the causal association through mediators. The main analysis suggested no causal association between genetically predicted plasma fibrinogen and γ-fibrinogen levels and the risk of AD, PD, and LBD. The effect estimates did not change in the follow-up sensitivity analyses and MVMR. However, the two-step MR analysis provides evidence that fibrinogen may contribute to the risk of AD via CRP levels. There was an inverse effect of adult height levels on the risk of AD. Our results support the effects of fibrinogen on the risk of AD through increasing plasma CRP levels. Our study found no evidence to support the effects of genetically determined fibrinogen and γ-fibrinogen levels on the risk of PD and LBD. Additionally, our findings suggested an inverse association between genetically determined adult height levels and the risk of AD. Future studies are needed to elucidate the underlying mechanisms and their clinical applications.

Potential proteomic alteration in the brain of Tg(SOD1*G93A)1Gur mice: A new pathogenesis insight of amyotrophic lateral sclerosis

The pathogenesis of amyotrophic lateral sclerosis (ALS) remains unclear. The recent studies have suggested that the protein abnormalities could play some important roles in ALS because several protein mutations were found in individuals with this disease. However, proteins that are currently known to be associated with ALS only explain the pathogenesis of this disease in a minority of cases, thus, further screening is needed to identify other ALS-related proteins. In this study, we systematically analyzed and compared the brain proteomic alterations between a mouse model of ALS, the Tg(SOD1*G93A)1Gur model, and wild-type mice using isobaric tags for relative and absolute quantitation (iTRAQ) as well as bioinformatics methods. The results revealed some significant up- and downregulated proteins at the different developmental stages in the ALS-like mice as well as the possibly related cellular components, molecular functions, biological processes, and pathways in the development of ALS. Our results identified some possible proteins that participate in the pathogenesis of ALS as well as the cellular components that are damaged by these proteins, we additionally identified the molecular functions, the biological processes, and the pathways of these proteins as well as the molecules that are associated with these pathways. This study represents an important preliminary investigation of the role of proteomic abnormalities in the pathogenesis of ALS, both in human patients and other animal models. We present some novel findings that may serve as a basis for further investigation of abnormal proteins that are involved in the pathogenesis of ALS.

Study on the Effect of Dexmedetomidine on Postoperative Cognitive Dysfunction and Inflammation in Aged Rats

Objective

The aim of this study is to investigate the effect of dexmedetomidine on cognitive dysfunction and inflammatory cytokines in the hippocampus after surgery in aged rats.

Methods

A total of 30 healthy male Sprague Dawley rats were divided into control group, sham group, and dexmedetomidine group. A splenectomy rat model was established and dexmedetomidine was intraperitoneally injected before operation. The cognitive function of rats was examined by Morris Water-Maze Test, open field experiment, and passive avoidance memory test. And the expression levels of IL-6, IL-1β, and TNF-α in the hippocampus were examined by ELISA.

Results

The escape latency for 5 continuous days in dexmedetomidine group was significantly decreased comparing with control group (all P < 0.05). The number of times of swimming and the percentage of swimming time in dexmedetomidine group were significantly more than those in control group (all P < 0.05). What is more, rats in dexmedetomidine group had the decreased time of stay in the central square and the increased number of standing times in comparison with the control group, and the statistical differences were found (all P < 0.05). Compared with the control group, dexmedetomidine intraperitoneally injected before surgery could significantly inhibit the expression levels of IL-6, IL-1β, and TNF-α in the hippocampus, and there were statistical differences (all P < 0.05).

Conclusion

Dexmedetomidine could significantly relieve the postoperative cognitive dysfunction in aged rats. The mechanism may be associated with the decreased inflammatory cytokines in the hippocampus.

Discovery of novel MIF inhibitors that attenuate microglial inflammatory activation by structures-based virtual screening and in vitro bioassays

Macrophage migration inhibitory factor (MIF) is a pluripotent pro-inflammatory cytokine and is related to acute and chronic inflammatory responses, immune disorders, tumors, and other diseases. In this study, an integrated virtual screening strategy and bioassays were used to search for potent MIF inhibitors. Twelve compounds with better bioactivity than the prototypical MIF-inhibitor ISO-1 (IC₅₀ = 14.41 μM) were identified by an in vitro enzymatic activity assay. Structural analysis revealed that these inhibitors have novel structural scaffolds. Compound 11 was then chosen for further characterization in vitro, and it exhibited marked anti-inflammatory efficacy in LPS-activated BV-2 microglial cells by suppressing the activation of nuclear factor kappa B (NF-κB) and mitogen-activated protein kinases (MAPKs). Our findings suggest that MIF may be involved in the regulation of microglial inflammatory activation and that small-molecule MIF inhibitors may serve as promising therapeutic agents for neuroinflammatory diseases.

An Insight into Recent Advances on Platelet Function in Health and Disease

Platelets play a variety of roles in vascular biology and are best recognized as primary hemostasis and thrombosis mediators. Platelets have a large number of receptors and secretory molecules that are required for platelet functionality. Upon activation, platelets release multiple substances that have the ability to influence both physiological and pathophysiological processes including inflammation, tissue regeneration and repair, cancer progression, and spreading. The involvement of platelets in the progression and seriousness of a variety of disorders other than thrombosis is still being discovered, especially in the areas of inflammation and the immunological response. This review represents an integrated summary of recent advances on the function of platelets in pathophysiology that connects hemostasis, inflammation, and immunological response in health and disease and suggests that antiplatelet treatment might be used for more than only thrombosis.

Chitosan oligosaccharides exert neuroprotective effects via modulating the PI3K/Akt/Bcl-2 pathway in a Parkinsonian model

Parkinson's disease (PD), the second most common neurodegenerative disease, is a threat to patients due to the inability to prevent or decelerate disease progression. Currently, most clinical drugs for the treatment of PD are synthetic drugs that always present undesirable adverse or toxic effects. Chitosan oligosaccharide (COS) is a natural oligosaccharide that has been considered relatively safe and studied in the therapeutic effects on different types of neuronal disorders. In this study, we separated four COS monomers (COSs) including chitobiose (COS2), chitotriose (COS3), chitotetraose (COS4) and chitopentaose (COS5) to explore their structure-activity relationship in PD mice induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). Techniques including TLC, HPLC, MS, and NMR were applied to investigate the purity and structure of the COSs. After the oral administration of COSs, behavior indexes, pathological indexes, cytokines, and expression of proteins in the nigrostriatal pathway of the mice were analyzed. The results showed that the four COSs were fully deacetylated and the purity was >90%. Additionally, the neurobehavioral deficits of the PD mice were improved by treatment with COSs. The results further proved that COSs could protect the TH-labelled dopaminergic neurons via reducing the overexpression of α-synuclein, alleviating neuroinflammation, and activating the PI3K/Akt/Bcl-2 pathway to reduce apoptosis. COS3 exhibited a better effect on protecting dopaminergic neurons; however, COS2 provided a better effect on reducing the overexpression of α-synuclein. To conclude, the neuroprotective activity makes COSs a viable candidate as an ingredient for healthcare products.

The Role of Transposable Elements of the Human Genome in Neuronal Function and Pathology

Transposable elements (TEs) have been extensively studied for decades. In recent years, the introduction of whole-genome and whole-transcriptome approaches, as well as single-cell resolution techniques, provided a breakthrough that uncovered TE involvement in host gene expression regulation underlying multiple normal and pathological processes. Of particular interest is increased TE activity in neuronal tissue, and specifically in the hippocampus, that was repeatedly demonstrated in multiple experiments. On the other hand, numerous neuropathologies are associated with TE dysregulation. Here, we provide a comprehensive review of literature about the role of TEs in neurons published over the last three decades. The first chapter of the present review describes known mechanisms of TE interaction with host genomes in general, with the focus on mammalian and human TEs; the second chapter provides examples of TE exaptation in normal neuronal tissue, including TE involvement in neuronal differentiation and plasticity; and the last chapter lists TE-related neuropathologies. We sought to provide specific molecular mechanisms of TE involvement in neuron-specific processes whenever possible; however, in many cases, only phenomenological reports were available. This underscores the importance of further studies in this area.

A comprehensive review of recent advances in the biological activities of 1,2,4-oxadiazoles

Nitrogen heterocycles play an essential role in medication development. The 1,2,4-oxadiazole heterocycle has been extensively studied, yielding a large variety of molecules with varied biological functions. The 1,2,4-oxadiazole shows bioisosteric equivalency with ester and amide moieties. In recent years, the 1,2,4-oxadiazole nucleus has received a lot of attention in medicinal chemistry. It was thought to be a pharmacophore component in the production of biologically intriguing drugs. This review presents a comprehensive overview of the recent achievements in the biological activities of 1,2,4-oxadiazoles as potential antimicrobial, anticancer, anti-inflammatory, neuroprotective, and antidiabetic agents. The structure-activity relationship and mechanisms of action are also reviewed.

Network pharmacology-based strategy to investigate pharmacological mechanisms of Andrographolide for treatment of vascular cognitive impairment

Vascular cognitive impairment (VCI) is the second most common form of dementia. Andrographolide (Andro) shows potential effects in anti-inflammation, anti-oxidative stress, and anti-apoptosis. We have obtained 48 potential genes related to the effect of Andro on VCI through network pharmacology analysis. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis were used to reveal significant enriched pathway of potential genes, and the mitogen-activated protein kinase (MAPK) pathway was screened out. To verify the results of network pharmacology, we tested the effects of Andro in VCI model induced by bilateral common carotid artery occlusion (BCCAO) surgery. The results showed that Andro treatment ameliorated the cognitive impairment induced by BCCAO. Immunohistochemistry study revealed that Andro could reduce neuronal damage and activation of microglia in the cortex and hippocampus in BCCAO rats. To test the MAPK pathway changes, we analyzed the expression of JNK, p38 and ERK and found that Andro reduced the levels of phosphorylated-ERK (p-ERK) and phosphorylated-p38 (p-p38) in BCCAO rats. In conclusion, Andro could improve neuronal survival, reduce neuroinflammation and ameliorate cognitive impairment in VCI. The underlying mechanisms of Andro treatment may be through the inhibition of MAPK pathway.

Therapeutic effects of crude extracts of Bacopa floribunda on beta-amyloid 1-42-induced Alzheimer’s disease via suppression of dyslipidemia, systemic inflammation and oxidative stress in male Wistar Rats

Aims

Bacopa floribunda (BF), an African traditional plant and its species have been widely used as brain tonic for memory enhancement. It has also been reported to help relieve anxiety and some psychological disorders. This study aimed to investigate the mechanisms of action of BF on Amyloid beta (Aβ) 1–42 peptides induced cognitive deficit in male Wistar rats.

Main methods

A total of 48 healthy male wistar rats were used for this study. Some groups were pre-treated with 200 mg/kg of BF extracts before a single bilateral injection of Aβ 1–42 while some were post-treated with BF for 21 days after Aβ1-42 exposure. Cognitive performance was evaluated using Y-Maze and Novel Object recognition tests. After treatments, hippocampal homogenates were assayed for the levels of Acetylcholinesterase, Na–K/ATPase activities, glutamate and Aβ1-42 concentrations among others.

Key findings

It was observed that Aβ1-42 caused cognitive impairment and BF extracts especially the ethanol extract was able to significantly (p < 0.05) reverse almost all the perturbations including lipid imbalance caused by Aβ1-42 assault mainly at the post-treatment level.

Significance

Administration of ethanol and aqueous extracts of BF mitigated the hazardous effect of Aβ1-42 observed in the blood plasma and hippocampal homogenates. In this context, we conclude that BF is an efficient cognitive enhancer that can help alleviate some symptoms associated with Alzheimer’s disease.

Yiqi Tongluo Fang could preventive and delayed development and formation of diabetic retinopathy through antioxidant and anti-inflammatory effects

BACKGROUND

Yiqi Tongluo Fang (YQTLF) is an effective prescription for the treatment of diabetic retinopathy (DR), but its mechanism of action remains unclear.

METHOD

The content of YQTLF was determined using liquid and gas chromatography-mass spectrometry (LC-MS and GC-MS, respectively). Twenty-five Sprague Dawley (SD) rats were randomly selected as the normal control group. One hundred SD streptozotocin-induced diabetes (type 1) rats were randomly divided into diabetic control, diabetic+insulin+ calcium dobesilate (CaD), and diabetic+insulin+ YQTLF groups, with 25 rats in each group. Bodyweight level was measured every 2 weeks. After 12 weeks of gavage, the glucose levels, lipids, oxidative stress, inflammation, retinal histopathology, and the blood-retinal barrier were assessed in each group. The p38 MAPK pathway was changed to explore its internal mechanism. The measurement data were expressed as mean ± standard deviation, and different statistical methods were used according to a normal distribution, square error, or not.

RESULTS

A total of 1024 valid peaks were identified in YQTLF using GC-MS. YQTLF significantly lowered the fasting blood glucose levels in diabetic rats. YQTLF early inhibited changes in retinal histology, capillaries, cells, and tight junction proteins (such as ZO-1, occludin, claudin-5, and VE-cadherin) before the formation and development of DR. These findings correlated with the alleviation of glucolipid metabolism, inflammation, and oxidative stress. The lncRNA MALAT1 and the PRC 2/p38 MAPK-related pathway, such as the expression of EZH2, SUZ12, EED, p38 MAPK, MMP-9, and VEGFR, were also correlated.

CONCLUSION

We have demonstrated the molecular and cellular mechanisms underlying the preventive and delayed development and formation of DR. YQTLF prevents changes in dyslipidemia, retinal histology, capillaries, cells, and tight junction proteins. These protective effects appear to be linked to its antioxidant and anti-inflammatory effects, which prevent the activation of intracellular signaling pathways, such as the lncRNA MALAT1 and PRC 2/p38 MAPK-related pathway.

RNA N6-Methyladenosine Modifications and Its Roles in Alzheimer's Disease

The importance of epitranscriptomics in regulating gene expression has received widespread attention. Recently, RNA methylation modifications, particularly N6-methyladenosine (m6A), have received marked attention. m6A, the most common and abundant type of eukaryotic methylation modification in RNAs, is a dynamic reversible modification that regulates nuclear splicing, stability, translation, and subcellular localization of RNAs. These processes are involved in the occurrence and development of many diseases. An increasing number of studies have focused on the role of m6A modification in Alzheimer's disease, which is the most common neurodegenerative disease. This review focuses on the general features, mechanisms, and functions of m6A methylation modification and its role in Alzheimer's disease.

Therapeutic promise of carotenoids as antioxidants and anti-inflammatory agents in neurodegenerative disorders

Neurodegenerative disorders (NDs) including Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, Huntington's disease, and multiple sclerosis have various disease-specific causal factors and pathological features. A very common characteristic of NDs is oxidative stress (OS), which takes place due to the elevated generation of reactive oxygen species during the progression of NDs. Furthermore, the pathological condition of NDs including an increased level of protein aggregates can further lead to chronic inflammation because of the microglial activation. Carotenoids (CTs) are naturally occurring pigments that play a significant role in averting brain disorders. More than 750 CTs are present in nature, and they are widely available in plants, microorganisms, and animals. CTs are accountable for the red, yellow, and orange pigments in several animals and plants, and these colors usually indicate various types of CTs. CTs exert various bioactive properties because of its characteristic structure, including anti-inflammatory and antioxidant properties. Due to the protective properties of CTs, levels of CTs in the human body have been markedly linked with the prevention and treatment of multiple diseases including NDs. In this review, we have summarized the relationship between OS, neuroinflammation, and NDs. In addition, we have also particularly focused on the antioxidants and anti-inflammatory properties of CTs in the management of NDs.

A Review of Pharmacology, Toxicity and Pharmacokinetics of 2,3,5,4'-Tetrahydroxystilbene-2-O-β-D-Glucoside

Polygonum multiflorum Thunb. (He-shou-wu in Chinese), a Chinese botanical drug with a long history, is widely used to treat a variety of chronic diseases in clinic, and has been given the reputation of “rejuvenating and prolonging life” in many places. 2,3,4′,5-tetrahydroxystilbene-2-O-β-D-glucoside (TSG, C₂₀H₂₂O₉) is the main and unique active ingredient isolated from Polygonum multiflorum Thunb., which has extensive pharmacological activities. Modern pharmacological studies have confirmed that TSG exhibits significant activities in treating various diseases, including inflammatory diseases, neurodegenerative diseases, cardiovascular diseases, hepatic steatosis, osteoporosis, depression and diabetic nephropathy. Therefore, this review comprehensively summarizes the pharmacological and pharmacokinetic properties of TSG up to 2021 by searching the databases of Web of Science, PubMed, ScienceDirect and CNKI. According to the data, TSG shows remarkable anti-inflammation, antioxidation, neuroprotection, cardiovascular protection, hepatoprotection, anti-osteoporosis, enhancement of memory and anti-aging activities through regulating multiple molecular mechanisms, such as NF-κB, AMPK, PI3K-AKT, JNK, ROS-NO, Bcl-2/Bax/Caspase-3, ERK1/2, TGF-β/Smad, Nrf2, eNOS/NO and SIRT1. In addition, the toxicity and pharmacokinetics of TSG are also discussed in this review, which provided direction and basis for the further development and clinical application of TSG.

Digoxin Exhibits Neuroprotective Properties in a Rat Model of Dementia

Alzheimer's disease (AD) is by far the most common cause of cognitive impairment in older adults. Current treatments are entirely focused on the symptoms of AD. A complex etiology for AD has been proposed recently, in which AD leads in elevated levels of inflammation. We previously studied digoxin's involvement in the sporadic-AD intracerebroventricular (ICV)-streptozotocin (STZ) animal model due to its anti-inflammatory and neuroprotective characteristics. 18 adult sprague-dawley rats were split into three groups: control (n = 6), STZ + Saline (n = 6), and STZ + Digoxin (n = 6). Twelve AD-induced rats were split into two groups using stereotaxy five days after STZ injection (3 mg/kg) into both lateral ventricles: one group got digoxin (0.1 mg/kg/day, i.p.) for three weeks, while the other group received saline. Following treatment, each subject was subjected to a passive avoidance learning (PAL) test, followed by brain tissue harvesting. The levels of tumor necrosis factor-alpha (TNF-α) and choline acetyl transferase (ChAT) were measured in the brain, and neurons were counted using Cresyl violet staining in cornu ammonis-1 (CA1) and cornu ammonis-3 (CA3) cornu ammonis (CA3). ICV-STZ significantly shortened PAL latency, increased brain TNF-α levels, decreased brain ChAT activity, and decreased hippocampus neuron number. On the other hand, digoxin significantly reduced all of these STZ-induced deleterious effects. Digoxin significantly rescued rats from memory loss caused by ICV-STZ by decreasing hippocampal cell death, neuroinflammation, and cholinergic deficiency. These findings suggest that digoxin may be beneficial in treating cognitive impairment and Alzheimer's disease.

A sensitive GRAB sensor for detecting extracellular ATP in vitro and in vivo

The purinergic transmitter ATP (adenosine 5'-triphosphate) plays an essential role in both the central and peripheral nervous systems, and the ability to directly measure extracellular ATP in real time will increase our understanding of its physiological functions. Here, we developed a sensitive GPCR activation-based ATP sensor called GRAB_ATP1.0, with a robust fluorescence response to extracellular ATP when expressed in several cell types. This sensor has sub-second kinetics, has ATP affinity in the range of tens of nanomolar, and can be used to localize ATP release with subcellular resolution. Using this sensor, we monitored ATP release under a variety of in vitro and in vivo conditions, including stimuli-induced and spontaneous ATP release in primary hippocampal cultures, injury-induced ATP release in a zebrafish model, and lipopolysaccharides-induced ATP-release events in individual astrocytes in the mouse cortex. Thus, the GRAB_ATP1.0 sensor is a sensitive, versatile tool for monitoring ATP release and dynamics under both physiological and pathophysiological conditions.

Anti-Inflammatory Gene Therapy Improves Spatial Memory Performance in a Mouse Model of Alzheimer's Disease

The immune system plays a critical role in neurodegenerative processes involved in Alzheimer’s disease (AD). In this study, a gene-based immunotherapeutic method examined the effects of anti-inflammatory cellular immune response elements (CIREs) in the amyloid-β protein precursor (AβPP) mouse model. Bi-monthly intramuscular administration, beginning at either 4 or 6 months, and examined at 7.5 through 16 months, with plasmids encoding Interleukin (IL)-10, IL-4, TGF-β polynucleotides, or a combination thereof, into AβPP mice improved spatial memory performance. This work demonstrates an efficient gene therapy strategy to downregulate neuroinflammation, and possibly prevent or delay cognitive decline in AD.

Ethyl Acetate Fractions of Papaver rhoeas L. and Papaver nudicaule L. Exert Antioxidant and Anti-Inflammatory Activities

Abnormal inflammation and oxidative stress are involved in various diseases. Papaver rhoeas L. possesses various pharmacological activities, and a previously reported analysis of the anti-inflammatory effect of P. nudicaule ethanol extracts and alkaloid profiles of the plants suggest isoquinoline alkaloids as potential pharmacologically active compounds. Here, we investigated anti-inflammatory and antioxidant activities of ethyl acetate (EtOAc) fractions of P. nudicaule and P. rhoeas extracts in lipopolysaccharide (LPS)-stimulated RAW264.7 cells. EtOAc fractions of P. nudicaule and P. rhoeas compared to their ethanol extracts showed less toxicity but more inhibitory activity against LPS-induced nitric oxide production. Moreover, EtOAc fractions lowered the LPS-induced production of proinflammatory molecules and cytokines and inhibited LPS-activated STAT3 and NF-κB, and additionally showed significant free radical scavenging activity and decreased LPS-induced reactive oxygen species and oxidized glutathione. EtOAc fractions of P. nudicaule increased the expression of HO-1, GCLC, NQO-1, and Nrf2 in LPS-stimulated cells and that of P. rhoeas enhanced NQO-1. Furthermore, metabolomic and biochemometric analyses of ethanol extracts and EtOAc fractions indicated that EtOAc fractions of P. nudicaule and P. rhoeas have potent anti-inflammatory and antioxidant activities, further suggesting that alkaloids in EtOAc fractions are potent active molecules of tested plants.

Rosinidin Attenuates Lipopolysaccharide-Induced Memory Impairment in Rats: Possible Mechanisms of Action Include Antioxidant and Anti-Inflammatory Effects

The investigation aimed to evaluate the favourable effects of rosinidin in lipopolysaccharide (LPS)-induced learning and memory impairment in rats. Adult Wistar rats (150–200 g) were segregated equally into four different groups and treated as below: Group 1 (normal) and Group 2 (LPS control) were administered orally with 3 mL of 0.5% SCMC (vehicle); Group 3 and Group 4 were test groups and orally administered with rosinidin lower dose (10 mg/kg) and higher dose 20 mg/kg. Daily, 1 h post-offer mentioned treatments, Group 1 animals were injected with normal saline (i.p.) and groups 2–4 were treated with 1 mg/kg/day of LPS. This treatment schedule was followed daily for 7 days. During the treatment, schedule rats were evaluated for spontaneous locomotor activity, memory, and learning abilities. The biochemical assessment was carried out of acetylcholine esterase (AChE), endogenous antioxidants (GSH, SOD, GPx, and catalase), oxidative stress marker MDA, neuroinflammatory markers (IL-6, IL-1β, TNF-α, and NF-κB), and BDNF. LPS-induced reduced spontaneous locomotor activity and memory impairment in the animals. Moreover, LPS reduced GSH, SOD, GPx, and catalase levels; altered activities of AChE; elevated levels of MDA, IL-6, IL-1β, TNF-α, and NF-κB; and attenuated the levels of BDNF in brain tissue. Administration of rosinidin to LPS-treated animals significantly reduced LPS-induced neurobehavioral impairments, oxidative stress, neuroinflammatory markers, and reversed the Ach enzyme activities and BDNF levels towards normal. Results demonstrated that rosinidin attenuates the effects of LPS on learning memory in rats.

Astragalin Protects against Spinal Cord Ischemia Reperfusion Injury through Attenuating Oxidative Stress-Induced Necroptosis

Spinal cord ischemia/reperfusion (SCI/R) injury is a devastating complication usually occurring after thoracoabdominal aortic surgery. However, it remains unsatisfactory for its intervention by using pharmacological strategies. Oxidative stress is a main pharmacological process involved in SCI/R, which will elicit downstream programmed cell death such as the novel defined necroptosis. Astragalin is a bioactive natural flavonoid with a wide spectrum of pharmacological activities. Herein, we firstly evaluated the effect of astragalin to oxidative stress as well as the possible downstream necroptosis after SCI/R in mice. Our results demonstrated that astragalin improves the ethological score and histopathological deterioration of SCI/R mice. Astragalin mitigates oxidative stress and ameliorates inflammation after SCI/R. Astragalin blocks necroptosis induced by SCI/R. That is, the amelioration of astragalin to the motoneuron injury and histopathological changes. Indicators of oxidative stress, inflammation, and necroptosis after SCI/R were significantly blocked. Summarily, we firstly illustrated the protection of astragalin against SCI/R through its blockage to the necroptosis at downstream of oxidative stress.

Sirtuin 3 (SIRT3) Pathways in Age-Related Cardiovascular and Neurodegenerative Diseases

Age-associated cardiovascular and neurodegenerative diseases lead to high morbidity and mortality around the world. Sirtuins are vital enzymes for metabolic adaptation and provide protective effects against a wide spectrum of pathologies. Among sirtuins, mitochondrial sirtuin 3 (SIRT3) is an essential player in preserving the habitual metabolic profile. SIRT3 activity declines as a result of aging-induced changes in cellular metabolism, leading to increased susceptibility to endothelial dysfunction, hypertension, heart failure and neurodegenerative diseases. Stimulating SIRT3 activity via lifestyle, pharmacological or genetic interventions could protect against a plethora of pathologies and could improve health and lifespan. Thus, understanding how SIRT3 operates and how its protective effects could be amplified, will aid in treating age-associated diseases and ultimately, in enhancing the quality of life in elders.

Unwanted Exacerbation of the Immune Response in Neurodegenerative Disease: A Time to Review the Impact

The COVID-19 pandemic imposed a series of behavioral changes that resulted in increased social isolation and a more sedentary life for many across all age groups, but, above all, for the elderly population who are the most vulnerable to infections and chronic neurodegenerative diseases. Systemic inflammatory responses are known to accelerate neurodegenerative disease progression, which leads to permanent damage, loss of brain function, and the loss of autonomy for many aged people. During the COVID-19 pandemic, a spectrum of inflammatory responses was generated in affected individuals, and it is expected that the elderly patients with chronic neurodegenerative diseases who survived SARSCoV-2 infection, it will be found, sooner or later, that there is a worsening of their neurodegenerative conditions. Using mouse prion disease as a model for chronic neurodegeneration, we review the effects of social isolation, sedentary living, and viral infection on the disease progression with a focus on sickness behavior and on the responses of microglia and astrocytes. Focusing on aging, we discuss the cellular and molecular mechanisms related to immunosenescence in chronic neurodegenerative diseases and how infections may accelerate their progression.

Chemical characterization and multifunctional neuroprotective effects of sesquiterpenoid-enriched Inula britannica flowers extract

Dried flowers of Inula britannica commercially serve as pharmaceutical/nutraceutical herbs in the manufacture of medicinal products and functional tea that has been reported to possess extensive biological property. However, the neuroprotective constituents in I. britannica flowers are not known. In the current study, phytochemicals of sesquiterpenoid-enriched I. britannica flowers extract and their potential multifunctional neuroprotective effects were investigated. Nineteen structurally diverse sesquiterpenoids, including two new sesquiterpenoid dimers, namely, inubritanolides A and B (1, 2), and four new sesquiterpenoid monomers (3-6), namely, 1-O-acetyl-6-O-chloracetylbritannilactone (3), 6-methoxybritannilactone (4), 1-hydroxy-10β-methoxy-4αH-1,10-secoeudesma-5(6),11(13)-dien-12,8β-olide (5) and 1-hydroxy-4αH-1,10-secoeudesma-5(6),10(14),11(13)-trien-12,8β-olide (6), as well as 13 known congeners (7-19) were isolated from this source. The structures of compounds 1-6 were elucidated by 1D- and 2D- NMR and HR-ESI-MS data, and their absolute configurations were discerned by electronic circular dichroism (ECD) data analysis and single crystal X-ray diffraction. Interestingly, inubritannolide A (1) is a new type [4 + 2] Diels-Alder dimer featuring a hepta-membered cycloether skeleton. Most of the compounds showed potential multifunctional neuroprotective effects, including antioxidative, anti-neuroinflammatory, and microglial polarization properties. Specifically, 1 and 6 displayed slight strong neuroprotective potency against different types of neuronal cells mediated by various inducers including H₂O₂, 6-hydroxydopamine (6-OHDA), and lipopolysaccharide (LPS). Overall, this is the first report on multifunctional neuroprotective effects of sesquiterpenoid-enriched I. britannica flowers extract, which supports its potential pharmaceutical/nutraceutical application in neurodegenerative diseases.

Prediction of post-stroke cognitive impairment using brain FDG PET: deep learning-based approach

PURPOSE

Post-stroke cognitive impairment can affect up to one third of stroke survivors. Since cognitive function greatly contributes to patients' quality of life, an objective quantitative biomarker for early prediction of dementia after stroke is required. We developed a deep-learning (DL)-based signature using positron emission tomography (PET) to objectively evaluate cognitive decline in patients with stroke.

METHODS

We built a DL model that differentiated Alzheimer's disease (AD) from normal controls (NC) using brain fluorodeoxyglucose (FDG) PET from the Alzheimer's Disease Neuroimaging Initiative database. The model was directly transferred to a prospectively enrolled cohort of patients with stroke to differentiate patients with dementia from those without dementia. The accuracy of the model was evaluated by the area under the curve values of receiver operating characteristic curves (AUC-ROC). We visualized the distribution of DL-based features and brain regions that the model weighted for classification. Correlations between cognitive signature from the DL model and clinical variables were evaluated, and survival analysis for post-stroke dementia was performed in patients with stroke.

RESULTS

The classification of AD vs. NC subjects was performed with AUC-ROC of 0.94 (95% confidence interval [CI], 0.89-0.98). The transferred model discriminated stroke patients with dementia (AUC-ROC = 0.75). The score of cognitive decline signature using FDG PET was positively correlated with age, neutrophil-lymphocyte ratio and platelet-lymphocyte ratio and negatively correlated with body mass index in patients with stroke. We found that the cognitive decline score was an independent risk factor for dementia following stroke (hazard ratio, 10.90; 95% CI, 3.59-33.09; P < 0.0001) after adjustment for other key variables.

CONCLUSION

The DL-based cognitive signature using FDG PET was successfully transferred to an independent stroke cohort. It is suggested that DL-based cognitive evaluation using FDG PET could be utilized as an objective biomarker for cognitive dysfunction in patients with cerebrovascular diseases.

The Dietary Inflammatory Index and Human Health: An Umbrella Review of Meta-Analyses of Observational Studies

Numerous observational studies have investigated the role of the Dietary Inflammatory Index (DII®) in chronic disease risk. The aims of this umbrella review and integrated meta-analyses were to systematically synthesize the observational evidence reporting on the associations between the DII and health outcomes based on meta-analyses, and to assess the quality and strength of the evidence for each associated outcome. This umbrella review with integrated meta-analyses investigated the association between the DII and a range of health outcomes based on meta-analyses of observational data. A credibility assessment was conducted for each outcome using the following criteria: statistical heterogeneity, 95% prediction intervals, evidence for small-study effect and/or excess significance bias, as well as effect sizes and P values using calculated random effects meta-analyses. In total, 15 meta-analyses reporting on 38 chronic disease-related outcomes were included, incorporating a total population of 4,360,111 subjects. Outcomes (n = 38) were examined through various study designs including case-control (n = 8), cross-sectional (n = 5), prospective (n = 5), and combination (n = 20) study designs. Adherence to a pro-inflammatory dietary pattern had a significant positive association with 27 (71%) of the included health outcomes (P value < 0.05). Using the credibility assessment, Class I (Convincing) evidence was identified for myocardial infarction only, Class II (Highly suggestive) evidence was identified for increased risk of all-cause mortality, overall risk of incident cancer, and risk of incident site-specific cancers (colorectal, pancreatic, respiratory, and oral cancers) with increasing (more pro-inflammatory) DII score. Most outcomes (n = 31) presented Class III (Suggestive) or lower evidence (Weak or No association). Pro-inflammatory dietary patterns were nominally associated with an increased risk of many chronic disease outcomes. However, the strength of evidence for most outcomes was limited. Further prospective studies are required to improve the precision of the effect size.

Pre- and Early Post-treatment With Arthrospira platensis (Spirulina) Extract Impedes Lipopolysaccharide-triggered Neuroinflammation in Microglia

Background: Uncontrolled neuroinflammation and microglia activation lead to cellular and tissue damage contributing to neurodegenerative and neurological disorders. Spirulina (Arthrospira platensis (Nordstedt) Gomont, or Spirulina platensis), a blue-green microalga, which belongs to the class of cyanobacteria, has been studied for its numerous health benefits, which include anti-inflammatory properties, among others. Furthermore, in vivo studies have highlighted neuroprotective effects of Spirulina from neuroinflammatory insults in different brain areas. However, the mechanisms underlying the anti-inflammatory effect of the microalga are not completely understood. In this study we examined the effect of pre- and post-treatment with an acetone extract of Spirulina (E1) in an in vitro model of LPS-induced microglia activation.

Methods: The effect of E1 on the release of IL-1β and TNF-α, expression of iNOS, nuclear factor erythroid 2–related factor 2 (Nrf2), and heme oxygenase-1 (HO-1), and the activation of NF-κB was investigated in primary microglia by ELISA, real-time PCR, and immunofluorescence.

Results: Pre- and early post-treatment with non-cytotoxic concentrations of E1 down-regulated the release of IL-1β and TNF-α, and the over-expression of iNOS induced by LPS. E1 also significantly blocked the LPS-induced nuclear translocation of NF-κB p65 subunit, and upregulated gene and protein levels of Nrf2, as well as gene expression of HO-1.

Conclusions: These results indicate that the extract of Spirulina can be useful in the control of microglia activation and neuroinflammatory processes. This evidence can support future in vivo studies to test pre- and post-treatment effects of the acetone extract from Spirulina.

Inflammatory Cascade in Alzheimer's Disease Pathogenesis: A Review of Experimental Findings

Alzheimer’s disease (AD) is the leading cause of dementia worldwide. Most AD patients develop the disease in late life, named late onset AD (LOAD). Currently, the most recognized explanation for AD pathology is the amyloid cascade hypothesis. It is assumed that amyloid beta (Aβ) aggregation and deposition are critical pathogenic processes in AD, leading to the formation of amyloid plaques, as well as neurofibrillary tangles, neuronal cell death, synaptic degeneration, and dementia. In LOAD, the causes of Aβ accumulation and neuronal loss are not completely clear. Importantly, the blood–brain barrier (BBB) disruption seems to present an essential role in the induction of neuroinflammation and consequent AD development. In addition, we propose that the systemic inflammation triggered by conditions like metabolic diseases or infections are causative factors of BBB disruption, coexistent inflammatory cascade and, ultimately, the neurodegeneration observed in AD. In this regard, the use of anti-inflammatory molecules could be an interesting strategy to treat, delay or even halt AD onset and progression. Herein, we review the inflammatory cascade and underlying mechanisms involved in AD pathogenesis and revise the anti-inflammatory effects of compounds as emerging therapeutic drugs against AD.

Do peripheral protein oligomers in neurodegenerative diseases shape T cell responses beyond the brain?

Neurodegenerative diseases place a devastating burden on affected individuals and their families, and new treatments are desperately needed for these common immune-mediated inflammatory conditions. While large aggregates of abnormal proteins in the brain cause significant damage, it is becoming clear that smaller soluble protein aggregates can also contribute to disease, by both direct and indirect mechanisms. These soluble protein oligomers can be found in patients' serum. Here, we describe recent research that identifies effects of model oligomer molecules on peripheral blood T cells, therefore providing an additional mechanism by which neurodegeneration may be worsened through amplification of peripheral adaptive immune responses.

NAD+ improves cognitive function and reduces neuroinflammation by ameliorating mitochondrial damage and decreasing ROS production in chronic cerebral hypoperfusion models through Sirt1/PGC-1α pathway

BACKGROUND

Microglial-mediated neuroinflammation plays an important role in vascular dementia, and modulating neuroinflammation has emerged as a promising treatment target. Nicotinamide adenine dinucleotide (NAD+) shows anti-inflammatory and anti-oxidant effects in many neurodegenerative disease models, but its role in the chronic cerebral hypoperfusion (CCH) is still unclear.

METHODS

The bilateral common carotid artery occlusion (BCCAO) was performed to establish CCH models in Sprague-Dawley rats. The rats were given daily intraperitoneal injection of NAD+ for 8 weeks. The behavioral test and markers for neuronal death and neuroinflammation were analyzed. Mitochondrial damage and ROS production in microglia were also assessed. RNA-seq was performed to investigate the mechanistic pathway changes. For in vitro studies, Sirt1 was overexpressed in BV2 microglial cells to compare with NAD+ treatment effects on mitochondrial injury and neuroinflammation.

RESULTS

NAD+ administration rescued cognitive deficits and inhibited neuroinflammation by protecting mitochondria and decreasing ROS production in CCH rats. Results of mechanistic pathway analysis indicated that the detrimental effects of CCH might be associated with decreased gene expression of PPAR-γ co-activator1α (PGC-1α) and its upstream transcription factor Sirt1, while NAD+ treatment markedly reversed their decrease. In vitro study confirmed that NAD+ administration had protective effects on hypoxia-induced neuroinflammation and mitochondrial damage, as well as ROS production in BV2 microglia via Sirt1/PGC-1α pathway. Sirt1 overexpression mimicked the protective effects of NAD+ treatment in BV2 microglia.

CONCLUSIONS

NAD+ ameliorated cognitive impairment and dampened neuroinflammation in CCH models in vivo and in vitro, and these beneficial effects were associated with mitochondrial protection and ROS inhibition via activating Sirt1/PGC-1α pathway.

The effect of the use of copper carbonate and copper nanoparticles in the diet of rats on the level of β-amyloid and acetylcholinesterase in selected organs

BACKGROUND

Copper has an important role in nervous system function, as a cofactor of many enzymes and in the synthesis of neurotransmitters. Both the dose and the chemical form of copper can determine the impact of this element on metabolism, the neurological system and the immune system.

AIMS

The aim of the study was to determine whether and in what form the addition of copper changes the level of amyloid beta and acetylcholinesterase level in selected rat tissues.

METHODS

Thirty, healthy, male, albino Wistar rats aged 7 weeks were randomly divided into 3 groups. Three experimental treatments were used to evaluate the effects of different levels and sources of Cu (6.5 mg kg of diet) in the diet: Cu₀ - rats fed a diet without Cu supplementation; Cu_salt - rats fed a diet with CuCO₃ (6.5 mg kg of diet) during two months of feeding; Cu_NPs - rats fed a diet with Cu nanoparticles (6.5 mg kg of diet) during two months of feeding. In blood serum and tissue homogenates there rated the indicators proving the potential neurodegenerative effect and epigenetic DNA damage induced by chemical form of copper or lack of additional copper supplementation in diet were determined. There were analysed: level of acetylcholinesterase, β-amyloid, low-density lipoprotein receptor-related protein 1, apyrimidinic endonuclease, thymidine glycosidase, alkylpurine-DNA-N-glycosylase and glycosylated acetylcholinesterase.

RESULTS

Irrespective of the form of copper added, it was found to increase acetylcholinesterase level in the brain, spleen and liver, as well as in the blood plasma of the rats. Copper in the form of CuCO₃ was found to increase acetylcholinesterase level in the kidneys. The addition of both forms of copper caused a marked increase in the plasma concentration of β-amyloid in comparison with the diet with no added Cu. The addition of both forms of copper caused a marked increase in the plasma concentration of β-amyloid in comparison with the diet with no added Cu.

CONCLUSIONS

A lack of added Cu in the diet of rats reduces the concentration of amyloid-β in the blood, whereas administration of copper, in the form of either CuNPs or CuCO₃, increases the level of this peptide in the blood. The use of copper in the form of CuNPs in the diet of rats does not increase the level of β-amyloid more than the use of the carbonate form of this element. The use of CuNPs or CuCO₃ in the diet of rats increases acetylcholinesterase level in the brain, spleen, liver, and blood. CuNPs in the diet of rats were not found to increase acetylcholinesterase level to a greater extent than Cu⁺² carbonate.

Dysregulated Microglial Cell Activation and Proliferation Following Repeated Antigen Stimulation

Upon reactivation of quiescent neurotropic viruses antigen (Ag)-specific brain resident-memory CD8+ T-cells (bT_RM) may respond to de novo-produced viral Ag through the rapid release of IFN-γ, which drives subsequent interferon-stimulated gene expression in surrounding microglia. Through this mechanism, a small number of adaptive bT_RM may amplify responses to viral reactivation leading to an organ-wide innate protective state. Over time, this brain-wide innate immune activation likely has cumulative neurotoxic and neurocognitive consequences. We have previously shown that HIV-1 p24 Ag-specific bT_RM persist within the murine brain using a heterologous prime-CNS boost strategy. In response to Ag restimulation, these bT_RM display rapid and robust recall responses, which subsequently activate glial cells. In this study, we hypothesized that repeated challenges to viral antigen (Ag) (modeling repeated episodes of viral reactivation) culminate in prolonged reactive gliosis and exacerbated neurotoxicity. To address this question, mice were first immunized with adenovirus vectors expressing the HIV p24 capsid protein, followed by a CNS-boost using Pr55Gag/Env virus-like particles (HIV-VLPs). Following the establishment of the bT_RM population [>30 days (d)], prime-CNS boost animals were then subjected to in vivo challenge, as well as re-challenge (at 14 d post-challenge), using the immunodominant HIV-1 AI9 CD8+ T-cell epitope peptide. In these studies, Ag re-challenge resulted in prolonged expression of microglial activation markers and an increased proliferative response, longer than the challenge group. This continued expression of MHCII and PD-L1 (activation markers), as well as Ki67 (proliferative marker), was observed at 7, 14, and 30 days post-AI9 re-challenge. Additionally, in vivo re-challenge resulted in continued production of inducible nitric oxide synthase (iNOS) with elevated levels observed at 7, 14 and 30 days post re-challenge. Interestingly, iNOS expression was significantly lower among challenged animals when compared to re-challenged groups. Furthermore, in vivo specific Ag re-challenge produced lower levels of arginase (Arg)-1 when compared with the challenged group. Taken together, these results indicate that repeated Ag-specific stimulation of adaptive immune responses leads to cumulative dysregulated microglial cell activation.

Vascular contributions to cognitive impairment and dementia: the emerging role of 20-HETE

The accumulation of extracellular amyloid-β (Aβ) and intracellular hyperphosphorylated τ proteins in the brain are the hallmarks of Alzheimer's disease (AD). Much of the research into the pathogenesis of AD has focused on the amyloid or τ hypothesis. These hypotheses propose that Aβ or τ aggregation is the inciting event in AD that leads to downstream neurodegeneration, inflammation, brain atrophy and cognitive impairment. Multiple drugs have been developed and are effective in preventing the accumulation and/or clearing of Aβ or τ proteins. However, clinical trials examining these therapeutic agents have failed to show efficacy in preventing or slowing the progression of the disease. Thus, there is a need for fresh perspectives and the evaluation of alternative therapeutic targets in this field. Epidemiology studies have revealed significant overlap between cardiovascular and cerebrovascular risk factors such as hypertension, diabetes, atherosclerosis and stroke to the development of cognitive impairment. This strong correlation has given birth to a renewed focus on vascular contributions to AD and related dementias. However, few genes and mechanisms have been identified. 20-Hydroxyeicosatetraenoic acid (20-HETE) is a potent vasoconstrictor that plays a complex role in hypertension, autoregulation of cerebral blood flow and blood-brain barrier (BBB) integrity. Multiple human genome-wide association studies have linked mutations in the cytochrome P450 (CYP) 4A (CYP4A) genes that produce 20-HETE to hypertension and stroke. Most recently, genetic variants in the enzymes that produce 20-HETE have also been linked to AD in human population studies. This review examines the emerging role of 20-HETE in AD and related dementias.

Therapeutic Applications of Terpenes on Inflammatory Diseases

In the last decades, the search for natural products with biological applications as alternative treatments for several inflammatory diseases has increased. In this respect, terpenes are a family of organic compounds obtained mainly from plants and trees, such as tea, cannabis, thyme, and citrus fruits like lemon or mandarin. These molecules present attractive biological properties such as analgesic and anticonvulsant activities. Furthermore, several studies have demonstrated that certain terpenes could reduce inflammation symptoms by decreasing the release of pro-inflammatory cytokines for example, the nuclear transcription factor-kappa B, interleukin 1, and the tumor necrosis factor-alpha. Thus, due to various anti-inflammatory drugs provoking side effects, the search and analysis of novel therapeutics treatments are attractive. In this review, the analysis of terpenes' chemical structure and their mechanisms in anti-inflammatory functions are addressed. Additionally, we present a general analysis of recent investigations about their applications as an alternative treatment for inflammatory diseases. Furthermore, we focus on terpenes-based nanoformulations and employed dosages to offer a global perspective of the state-of-the-art.

Silica-coated magnetic nanoparticles activate microglia and induce neurotoxic D-serine secretion

BACKGROUND

Nanoparticles have been studied for brain imaging, diagnosis, and drug delivery owing to their versatile properties due to their small sizes. However, there are growing concerns that nanoparticles may exert toxic effects in the brain. In this study, we assessed direct nanotoxicity on microglia, the resident macrophages of the central nervous system, and indirect toxicity on neuronal cells exerted by silica-coated magnetic nanoparticles containing rhodamine B isothiocyanate dye [MNPs@SiO2(RITC)].

METHODS

We investigated MNPs@SiO2(RITC)-induced biological changes in BV2 murine microglial cells via RNA-sequencing-based transcriptome analysis and gas chromatography-mass spectrometry-based intracellular and extracellular amino acid profiling. Morphological changes were analyzed by transmission electron microscopy. Indirect effects of MNPs@SiO2(RITC) on neuronal cells were assessed by Transwell-based coculture with MNPs@SiO2(RITC)-treated microglia. MNPs@SiO2(RITC)-induced biological changes in the mouse brain in vivo were examined by immunohistochemical analysis.

RESULTS

BV2 murine microglial cells were morphologically activated and the expression of Iba1, an activation marker protein, was increased after MNPs@SiO2(RITC) treatment. Transmission electron microscopy analysis revealed lysosomal accumulation of MNPs@SiO2(RITC) and the formation of vesicle-like structures in MNPs@SiO2(RITC)-treated BV2 cells. The expression of several genes related to metabolism and inflammation were altered in 100 µg/ml MNPs@SiO2(RITC)-treated microglia when compared with that in non-treated (control) and 10 µg/ml MNPs@SiO2(RITC)-treated microglia. Combined transcriptome and amino acid profiling analyses revealed that the transport of serine family amino acids, including glycine, cysteine, and serine, was enhanced. However, only serine was increased in the growth medium of activated microglia; especially, excitotoxic D-serine secretion from primary rat microglia was the most strongly enhanced. Activated primary microglia reduced intracellular ATP levels and proteasome activity in cocultured neuronal cells, especially in primary cortical neurons, via D-serine secretion. Moreover, ubiquitinated proteins accumulated and inclusion bodies were increased in primary dopaminergic and cortical neurons cocultured with activated primary microglia. In vivo, MNPs@SiO2(RITC), D-serine, and ubiquitin aggresomes were distributed in the MNPs@SiO2(RITC)-treated mouse brain.

CONCLUSIONS

MNPs@SiO2(RITC)-induced activation of microglia triggers excitotoxicity in neurons via D-serine secretion, highlighting the importance of neurotoxicity mechanisms incurred by nanoparticle-induced microglial activation.

Upregulation of IL-1 Receptor Antagonist by Aspirin in Glial Cells via Peroxisome Proliferator-Activated Receptor-Alpha

BACKGROUND

Neuroinflammation is a recognized aspect of Alzheimer's disease (AD) and other neurological illnesses. Interleukin 1 receptor antagonist (IL-1Ra) is an anti-inflammatory molecule, which inhibits inflammatory molecules in different cells including brain cells. However, mechanisms for upregulating IL-1Ra in brain cells are poorly understood.

OBJECTIVE

Since aspirin is a widely available pain reliever that shows promise beyond its known pain-relieving capacity, we examined whether aspirin could upregulate the IL-1Ra in the brain.

METHODS

We employed PCR, real-time PCR, western blot, immunostaining, chromatin immunoprecipitation (ChIP), and lentiviral transduction in glial cells. 5xFAD mice, an animal model of AD, were treated with aspirin orally via gavage.

RESULTS

Aspirin increased the expression of IL-1Ra mRNA and protein in primary mouse astrocytes and mouse BV-2 microglial cells. While investigating the mechanism, we found that the IL-1Ra gene promoter harbors peroxisome proliferator response element (PPRE) and that aspirin upregulated IL-1Ra in astrocytes isolated from peroxisome proliferator-activated receptor-beta knockout (PPARβ-/-), but not PPARα-/-, mice. Moreover, we observed that aspirin bound to tyrosine 314 residue of PPARα to stimulate IL-1Ra and that aspirin treatment also increased the recruitment of PPARα to the IL-1Ra promoter. Accordingly, aspirin increased IL-1Ra in vivo in the brain of wild type and PPARβ-/-, but not in PPARα-/- mice. Similarly, aspirin treatment also increased astroglial and microglial IL-1Ra in the cortex of 5xFAD, but not 5xFAD/PPARα-/- mice.

CONCLUSION

Aspirin may reduce the severity of different neurological conditions by upregulating IL-1Ra and reducing the inflammation.

Expression of Low Level of VPS35-mCherry Fusion Protein Diminishes Vps35 Depletion Induced Neuron Terminal Differentiation Deficits and Neurodegenerative Pathology, and Prevents Neonatal Death

Vps35 (vacuolar protein sorting 35) is a key component of retromer that consists of Vps35, Vps26, and Vps29 trimers, and sortin nexin dimers. Dysfunctional Vps35/retromer is believed to be a risk factor for development of various neurodegenerative diseases. Vps35Neurod6 mice, which selectively knock out Vps35 in Neurod6-Cre+ pyramidal neurons, exhibit age-dependent impairments in terminal differentiation of dendrites and axons of cortical and hippocampal neurons, neuro-degenerative pathology (i.e., increases in P62 and Tdp43 (TAR DNA-binding protein 43) proteins, cell death, and reactive gliosis), and neonatal death. The relationships among these phenotypes and the underlying mechanisms remain largely unclear. Here, we provide evidence that expression of low level of VPS35-mCherry fusion protein in Vps35Neurod6 mice could diminish the phenotypes in an age-dependent manner. Specifically, we have generated a conditional transgenic mouse line, LSL-Vps35-mCherry, which expresses VPS35-mCherry fusion protein in a Cre-dependent manner. Crossing LSL-Vps35-mCherry with Vps35Neurod6 to obtain TgVPS35-mCherry, Vps35Neurod6 mice prevent the neonatal death and diminish the dendritic morphogenesis deficit and gliosis at the neonatal, but not the adult age. Further studies revealed that the Vps35-mCherry transgene expression was low, and the level of Vps35 mRNA comprised only ~5-7% of the Vps35 mRNA of control mice. Such low level of VPS35-mCherry could restore the amount of other retromer components (Vps26a and Vps29) at the neonatal age (P14). Importantly, the neurodegenerative pathology presented in the survived adult TgVps35-mCherry; Vps35Neurod6 mice. These results demonstrate the sufficiency of low level of VPS35-mCherry fusion protein to diminish the phenotypes in Vps35Neurod6 mice at the neonatal age, verifying a key role of neuronal Vps35 in stabilizing retromer complex proteins, and supporting the view for Vps35 as a potential therapeutic target for neurodegenerative diseases.

RNA sequencing of whole blood reveals early alterations in immune cells and gene expression in Parkinson's disease

Changes in the blood-based RNA transcriptome have the potential to inform biomarkers of Parkinson's disease (PD) progression. Here we sequenced a discovery set of whole-blood RNA species in 4,871 longitudinally collected samples from 1,570 clinically phenotyped individuals from the Parkinson's Progression Marker Initiative (PPMI) cohort. Samples were sequenced to an average of 100 million read pairs to create a high-quality transcriptome. Participants with PD in the PPMI had significantly altered RNA expression (>2,000 differentially expressed genes), including an early and persistent increase in neutrophil gene expression, with a concomitant decrease in lymphocyte cell counts. This was validated in a cohort from the Parkinson's Disease Biomarkers Program (PDBP) consisting of 1,599 participants and by alterations in immune cell subtypes. This publicly available transcriptomic dataset, coupled with available detailed clinical data, provides new insights into PD biological processes impacting whole blood and new paths for developing diagnostic and prognostic PD biomarkers.

The Effect of Ferula communis Extract in Escherichia coli Lipopolysaccharide-Induced Neuroinflammation in Cultured Neurons and Oligodendrocytes

In recent decades, interest in natural compounds has increased exponentially due to their numerous beneficial properties in the treatment of various acute and chronic diseases. A group of plant derivatives with great scientific interest is terpenic compounds. Among the plants richest in terpenes, the genus Ferula L. is one of the most representative, and ferutinin, the most common sesquiterpene, is extracted from the leaves, rhizome, and roots of this plant. As reported in the scientific literature, ferutinin possesses antioxidant and anti-inflammatory properties, as well as valuable estrogenic properties. Neurodegenerative and demyelinating diseases are devastating conditions for which a definite cure has not yet been established. The mechanisms involved in these diseases are still poorly understood, and oxidative stress is considered to be both a key modulator and a common denominator. In the proposed experimental system, co-cultured human neurons (SH-SY5Y) and human oligodendrocytes (MO3.13) were treated with the pro-inflammatory agent lipopolysaccharide at a concentration of 1 μg/mL for 24 h or pretreated with ferutinin (33 nM) for 24 h and subsequently exposed to lipopolysaccharide 1 μg/mL for 24 h. Further studies would, however, be needed to establish whether this natural compound can be used as a support strategy in pathologies characterized by progressive inflammation and oxidative stress phenomena.

Analysis of circulating protein aggregates as a route of investigation into neurodegenerative disorders

Plasma proteome composition reflects the inflammatory and metabolic state of the organism and can be predictive of system-level and organ-specific pathologies. Circulating protein aggregates are enriched with neurofilament heavy chain-axonal proteins involved in brain aggregate formation and recently identified as biomarkers of the fatal neuromuscular disorder amyotrophic lateral sclerosis. Using unbiased proteomic methods, we have fully characterized the content in neuronal proteins of circulating protein aggregates from amyotrophic lateral sclerosis patients and healthy controls, with reference to brain protein aggregate composition. We also investigated circulating protein aggregate protein aggregation propensity, stability to proteolytic digestion and toxicity for neuronal and endothelial cell lines. Circulating protein aggregates separated by ultracentrifugation are visible as electron-dense macromolecular particles appearing as either large globular or as small filamentous formations. Analysis by mass spectrometry revealed that circulating protein aggregates obtained from patients are enriched with proteins involved in the proteasome system, possibly reflecting the underlying basis of dysregulated proteostasis seen in the disease, while those from healthy controls show enrichment of proteins involved in metabolism. Compared to the whole human proteome, proteins within circulating protein aggregates and brain aggregates show distinct chemical features of aggregation propensity, which appear dependent on the tissue or fluid of origin and not on the health status. Neurofilaments' two high-mass isoforms (460 and 268 kDa) showed a strong differential expression in amyotrophic lateral sclerosis compared to healthy control circulating protein aggregates, while aggregated neurofilament heavy chain was also partially resistant to enterokinase proteolysis in patients, demonstrated by immunoreactive bands at 171 and 31 kDa fragments not seen in digested healthy controls samples. Unbiased proteomics revealed that a total of 4973 proteins were commonly detected in circulating protein aggregates and brain, including 24 expressed from genes associated with amyotrophic lateral sclerosis. Interestingly, 285 circulating protein aggregate proteins (5.7%) were regulated (P < 0.05) and are present in biochemical pathways linked to disease pathogenesis and protein aggregation. Biologically, circulating protein aggregates from both patients and healthy controls had a more pronounced effect on the viability of hCMEC/D3 endothelial and PC12 neuronal cells compared to immunoglobulins extracted from the same plasma samples. Furthermore, circulating protein aggregates from patients exerted a more toxic effect than healthy control circulating protein aggregates on both cell lines at lower concentrations (P: 0.03, in both cases). This study demonstrates that circulating protein aggregates are significantly enriched with brain proteins which are representative of amyotrophic lateral sclerosis pathology and a potential source of biomarkers and therapeutic targets for this incurable disorder.

Curcumin-laden dual-targeting fucoidan/chitosan nanocarriers for inhibiting brain inflammation via intranasal delivery

Curcumin can reduce the production of brain inflammatory mediators and symptoms of brain diseases. However, a large amount of free curcumin needs to be administered to achieve an effective level in the brain because of its poor water-solubility. Fucoidan and chitosan were reported to respectively target P-selectin and acidic microenvironment expressed by pathologically inflammatory cells/tissues. Herein, the self-assembly of chitosan and fucoidan which could encapsulate curcumin was developed to form the multi-stimuli-responsive nanocarriers, and their pathological pH- and P-selectin-responsive aspects were characterized. Through intranasal delivery to the brain, these curcumin-containing chitosan/fucoidan nanocarriers with dual pH-/P-selectin-targeting properties to the brain lesions improved drug delivery, distribution, and accumulation in the inflammatory brain lesions as evidenced by an augmented inhibitory effect against brain inflammation. This promising multifunctional nanocarrier with a novel drug-delivery route should allow potential clinical biomedical uses by neurosurgeon in the future.

Natural Glycan Derived Biomaterials for Inflammation Targeted Drug Delivery

Inflammation is closely related to a variety of fatal or chronic diseases. Hence, targeting inflammation provides an alternative approach to improve the therapeutic outcome of diseases such as solid tumors, neurological diseases, and metabolic diseases. Polysaccharides are natural components with immune regulation, anti-virus, anti-cancer, anti-inflammation, and anti-oxidation activities. Herein, this review highlights recent progress in the polysaccharide-based drug delivery systems for achieving inflammation targeting and its related disease treatment. Moreover, the chemical modification and the construction of polysaccharide materials for drug delivery are discussed in detail.