Chronic neuroinflammation in Alzheimer's disease: new perspectives on animal models and promising candidate drugs

Alkaloids as drug leads in Alzheimer's treatment: Mechanistic and therapeutic insights

Alzheimer's disease (AD) has few effective treatment options and continues to be a major global health concern. AD is a neurodegenerative disease that typically affects elderly people. Alkaloids have potential sources for novel drug discovery due to their diverse chemical structures and pharmacological activities. Alkaloids, natural products with heterocyclic nitrogen-containing structures, are considered potential treatments for AD. This review explores the neuroprotective properties of alkaloids in AD, focusing on their ability to regulate pathways such as amyloid-beta aggregation, oxidative stress, synaptic dysfunction, tau hyperphosphorylation, and neuroinflammation. The FDA has approved alkaloids such as acetylcholinesterase inhibitors like galantamine and rivastigmine. This article explores AD's origins, current market medications, and clinical applications of alkaloids in AD therapy. This review explores the development of alkaloid-based drugs for AD, focusing on pharmacokinetics, blood-brain barrier penetration, and potential adverse effects. Future research should focus on the clinical evaluation of promising alkaloids, developing recently discovered alkaloids, and the ongoing search for novel alkaloids for medical treatment. A pharmaceutical option containing an alkaloid may potentially slow down the progression of AD while enhancing its symptoms. This review highlights the potential of alkaloids as valuable drug leads in treating AD, providing a comprehensive understanding of their mechanisms of action and therapeutic implications.

mTOR signaling and Alzheimer's disease: What we know and where we are?

Despite the great body of research done on Alzheimer's disease, the underlying mechanisms have not been vividly investigated. To date, the accumulation of amyloid-beta plaques and tau tangles constitutes the hallmark of the disease; however, dysregulation of the mammalian target of rapamycin (mTOR) seems to be significantly involved in the pathogenesis of the disease as well. mTOR, as a serine-threonine protein kinase, was previously known for controlling many cellular functions such as cell size, autophagy, and metabolism. In this regard, mammalian target of rapamycin complex 1 (mTORC1) may leave anti-aging impacts by robustly inhibiting autophagy, a mechanism that inhibits the accumulation of damaged protein aggregate and dysfunctional organelles. Formation and aggregation of neurofibrillary tangles and amyloid-beta plaques seem to be significantly regulated by mTOR signaling. Understanding the underlying mechanisms and connection between mTOR signaling and AD may suggest conducting clinical trials assessing the efficacy of rapamycin, as an mTOR inhibitor drug, in managing AD or may help develop other medications. In this literature review, we aim to elaborate mTOR signaling network mainly in the brain, point to gaps of knowledge, and define how and in which ways mTOR signaling can be connected with AD pathogenesis and symptoms.

Medicinal herbal remedies in neurodegenerative diseases: an update on antioxidant potential

It has been widely documented that medicinal herbal remedies are effective, have fewer side effects than conventional medicine, and have a synergistic effect on health collaborations in the fight against complicated diseases. Traditional treatments for neurological problems in ancient times sometimes involved the use of herbal remedies and conventional methods from East Asian countries including India, Japan, China, and Korea. We collected and reviewed studies on plant-derived neuroprotective drugs and tested them in neurotoxic models. Basic research, preclinical and clinical transgene research can benefit from in silico, in vitro, and in vivo investigations. Research, summaries of the extracts, fractions, and herbal ingredients were compiled from popular scientific databases, which were then examined according to origin and bioactivity. Given the complex and varied causes of neurodegeneration, it may be beneficial to focus on multiple mechanisms of action and a neuroprotection approach. This approach aims to prevent cell death and restore function to damaged neurons, offering promising strategies for preventing and treating neurodegenerative diseases. Neurodegenerative illnesses can potentially be treated with natural compounds that have been identified as neuroprotective agents. To gain deeper insights into the neuropharmacological mechanisms underlying the neuroprotective and therapeutic properties of naturally occurring antioxidant phytochemical compounds in diverse neurodegenerative diseases, this study aims to comprehensively review such compounds, focusing on their modulation of apoptotic markers such as caspase, Bax, Bcl-2, and proinflammatory markers. In addition, we delve into a range of efficacies of antioxidant phytochemical compounds as neuroprotective agents in animal models. They reduce the oxidative stress of the brain and have been shown to have anti-apoptotic effects. Many researches have demonstrated that plant extracts or bioactive compounds can fight neurodegenerative disorders. Herbal medications may offer neurodegenerative disease patients' new treatments. This may be a cheaper and more culturally appropriate alternative to standard drugs for millions of people with age-related NDDs.

Alzheimer's Disease Puzzle: Delving into Pathogenesis Hypotheses

Alzheimer's disease (AD) is a prevalent neurodegenerative disease characterized by both amnestic and non-amnestic clinical manifestations. It accounts for approximately 60-70% of all dementia cases worldwide. With the increasing number of AD patients, elucidating underlying mechanisms and developing corresponding interventional strategies are necessary. Hypotheses about AD such as amyloid cascade, Tau hyper-phosphorylation, neuroinflammation, oxidative stress, mitochondrial dysfunction, cholinergic, and vascular hypotheses are not mutually exclusive, and all of them play a certain role in the development of AD. The amyloid cascade hypothesis is currently the most widely studied; however, other hypotheses are also gaining support. This article summarizes the recent evidence regarding major pathological hypotheses of AD and their potential interplay, as well as the strengths and weaknesses of each hypothesis and their implications for the development of effective treatments. This could stimulate further studies and promote the development of more effective therapeutic strategies for AD.

Neuroinflammation in Alzheimer's Disease: A Potential Role of Nose-Picking in Pathogen Entry via the Olfactory System?

Alzheimer's disease (AD) is a complex neurodegenerative disorder characterized by progressive cognitive decline and memory impairment. Many possible factors might contribute to the development of AD, including amyloid peptide and tau deposition, but more recent evidence suggests that neuroinflammation may also play an-at least partial-role in its pathogenesis. In recent years, emerging research has explored the possible involvement of external, invading pathogens in starting or accelerating the neuroinflammatory processes in AD. In this narrative review, we advance the hypothesis that neuroinflammation in AD might be partially caused by viral, bacterial, and fungal pathogens entering the brain through the nose and the olfactory system. The olfactory system represents a plausible route for pathogen entry, given its direct anatomical connection to the brain and its involvement in the early stages of AD. We discuss the potential mechanisms through which pathogens may exploit the olfactory pathway to initiate neuroinflammation, one of them being accidental exposure of the olfactory mucosa to hands contaminated with soil and feces when picking one's nose.

Chronic neuroinflammation during aging leads to cholinergic neurodegeneration in the mouse medial septum

BACKGROUND

Low-grade, chronic inflammation in the central nervous system characterized by glial reactivity is one of the major hallmarks for aging-related neurodegenerative diseases like Alzheimer's disease (AD). The basal forebrain cholinergic neurons (BFCN) provide the primary source of cholinergic innervation of the human cerebral cortex and may be differentially vulnerable in various neurodegenerative diseases. However, the impact of chronic neuroinflammation on the cholinergic function is still unclear.

METHODS

To gain further insight into age-related cholinergic decline, we investigated the cumulative effects of aging and chronic neuroinflammation on the structure and function of the septal cholinergic neurons in transgenic mice expressing interleukin-6 under the GFAP promoter (GFAP-IL6), which maintains a constant level of gliosis. Immunohistochemistry combined with unbiased stereology, single cell 3D morphology analysis and in vitro whole cell patch-clamp measurements were used to validate the structural and functional changes of BFCN and their microglial environment in the medial septum.

RESULTS

Stereological estimation of MS microglia number displayed significant increase across all three age groups, while a significant decrease in cholinergic cell number in the adult and aged groups in GFAP-IL6 mice compared to control. Moreover, we observed age-dependent alterations in the electrophysiological properties of cholinergic neurons and an increased excitability profile in the adult GFAP-IL6 group due to chronic neuroinflammation. These results complimented the significant decrease in hippocampal pyramidal spine density seen with aging and neuroinflammation.

CONCLUSIONS

We provide evidence of the significant impact of both aging and chronic glial activation on the cholinergic and microglial numbers and morphology in the MS, and alterations in the passive and active electrophysiological membrane properties of septal cholinergic neurons, resulting in cholinergic dysfunction, as seen in AD. Our results indicate that aging combined with gliosis is sufficient to cause cholinergic disruptions in the brain, as seen in dementias.

From the Bush to the Brain: Preclinical Stages of Ethnobotanical Anti-Inflammatory and Neuroprotective Drug Discovery-An Australian Example

The Australian rainforest is a rich source of medicinal plants that have evolved in the face of dramatic environmental challenges over a million years due to its prolonged geographical isolation from other continents. The rainforest consists of an inherent richness of plant secondary metabolites that are the most intense in the rainforest. The search for more potent and more bioavailable compounds from other plant sources is ongoing, and our short review will outline the pathways from the discovery of bioactive plants to the structural identification of active compounds, testing for potency, and then neuroprotection in a triculture system, and finally, the validation in an appropriate neuro-inflammatory mouse model, using some examples from our current research. We will focus on neuroinflammation as a potential treatment target for neurodegenerative diseases including multiple sclerosis (MS), Parkinson's (PD), and Alzheimer's disease (AD) for these plant-derived, anti-inflammatory molecules and highlight cytokine suppressive anti-inflammatory drugs (CSAIDs) as a better alternative to conventional nonsteroidal anti-inflammatory drugs (NSAIDs) to treat neuroinflammatory disorders.

Origanum majorana L. protects against neuroinflammation-mediated cognitive impairment: a phyto-pharmacological study

BACKGROUND

Neuroinflammation and oxidative stress are critical players in the pathogenesis of numerous neurodegenerative diseases, such as Alzheimer's disease (AD) which is responsible for most cases of dementia in the elderly. With the lack of curative treatments, natural phenolics are potential candidates to delay the onset and progression of such age-related disorders due to their potent antioxidant and anti-inflammatory effects. This study aims at assessing the phytochemical characteristics of Origanum majorana L. (OM) hydroalcohol extract and its neuroprotective activities in a murine neuroinflammatory model.

METHODS

OM phytochemical analysis was done by HPLC/PDA/ESI-MSⁿ. Oxidative stress was induced in vitro by hydrogen peroxide and cell viability was measured using WST-1 assay. Swiss albino mice were injected intraperitoneally with OM extract at a dose of 100 mg/kg for 12 days and with 250 μg/kg LPS daily starting from day 6 to induce neuroinflammation. Cognitive functions were assessed by novel object recognition and Y-maze behavioral tests. Hematoxylin and eosin staining was used to assess the degree of neurodegeneration in the brain. Reactive astrogliosis and inflammation were assessed by immunohistochemistry using GFAP and COX-2 antibodies, respectively.

RESULTS

OM is rich in phenolics, with rosmarinic acid and its derivatives being major constituents. OM extract and rosmarinic acid significantly protected microglial cells against oxidative stress-induced cell death (p < 0.001). OM protected against the LPS-induced alteration of recognition and spatial memory in mice (p < 0.001) and (p < 0.05), respectively. Mice that received OM extract prior to the induction of neuroinflammation showed comparable histology to control brains, with no overt neurodegeneration. Furthermore, OM pre-treatment decreased the immunohistochemistry profiler score of GFAP from positive to low positive and COX-2 from low positive to negative in the brain tissue, compared to the LPS group.

CONCLUSION

These findings highlight the potential preventive effects of OM phenolics against neuroinflammation and pave the way toward drug discovery and development for neurodegenerative disorders.

Inflammatory Processes in Alzheimer's Disease-Pathomechanism, Diagnosis and Treatment: A Review

Alzheimer's disease is one of the most commonly diagnosed cases of senile dementia in the world. It is an incurable process, most often leading to death. This disease is multifactorial, and one factor of this is inflammation. Numerous mediators secreted by inflammatory cells can cause neuronal degeneration. Neuritis may coexist with other mechanisms of Alzheimer's disease, contributing to disease progression, and may also directly underlie AD. Although much has been established about the inflammatory processes in the pathogenesis of AD, many aspects remain unexplained. The work is devoted in particular to the pathomechanism of inflammation and its role in diagnosis and treatment. An in-depth and detailed understanding of the pathomechanism of neuroinflammation in Alzheimer's disease may help in the development of diagnostic methods for early diagnosis and may contribute to the development of new therapeutic strategies for the disease.

Apigenin improves cytotoxicity of antiretroviral drugs against HTLV-1 infected cells through the modulation of AhR signaling

Objectives

HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) is a neuroinflammatory autoimmune disease characterized by high levels of infected immortalized T cells in circulation, which makes it difficult for antiretroviral (ART) drugs to work effectively. In previous studies, we established that Apigenin, a flavonoid, can exert immunomodulatory effects to reduce neuroinflammation. Flavonoids are natural ligands for the aryl hydrocarbon receptor (AhR), which is a ligand activated endogenous receptor involved in the xenobiotic response. Consequently, we tested Apigenin's synergy in combination with ART against the survival of HTLV-1-infected cells.

Methods

First, we established a direct protein-protein interaction between Apigenin and AhR. We then demonstrated that Apigenin and its derivative VY-3-68 enter activated T cells, drive nuclear shuttling of AhR, and modulate its signaling both at RNA and protein level.

Results

In HTLV-1 producing cells with high AhR expression, Apigenin cooperates with ARTs such as Lopinavir (LPN) and Zidovudine (AZT), to impart cytotoxicity by exhibiting a major shift in IC50 that was reversed upon AhR knockdown. Mechanistically, Apigenin treatment led to an overall downregulation of NF-κB and several other pro-cancer genes involved in survival.

Conclusions

This study suggest the potential combinatorial use of Apigenin with current first-line antiretrovirals for the benefit of patients affected by HTLV-1 associated pathologies.

Neuroprotective effects of sesamol against LPS-induced spatial learning and memory deficits are mediated via anti-inflammatory and antioxidant activities in the rat brain

Objective

Sesamol is a phenolic lignan extracted from sesame seeds, and it possesses anti-inflammatory and antioxidant activities. Lipopolysaccharide (LPS) is known to produce neuroinflammatory responses and memory impairment. The current study aimed to investigate the protective influence of sesamol against LPS-mediated neuroinflammation and memory impairment.

Materials and Methods

Sesamol (10 and 50 mg/kg) was injected to Wistar rats for two weeks. Then, animals received LPS injection (1 mg/kg) for five days, while treatment with sesamol was performed 30 min before LPS injection. Spatial learning and memory were assessed by the Morris water maze (MWM), two hours after LPS injection on days 15-19. Biochemical assessments were performed after the end of behavioral experiments.

Results

LPS-administered rats showed spatial learning and memory deficits, since they spent more time in the MWM to find the hidden platform and less time in the target quadrant. Besides these behavioral changes, tumor necrosis factor-α (TNF-α) and lipid peroxidation levels were increased, while total thiol level was decreased in the hippocampus and/or cerebral cortex. In addition, sesamol treatment (50 mg/kg) for three weeks decreased the escape latency and increased the time on probe trial. Sesamol also reduced lipid peroxidation and TNF-α level, while enhanced total thiol level in the brain of LPS-exposed rats.

Conclusion

Supplementation of sesamol attenuated learning and memory impairments in LPS-treated rats via antioxidative and anti-inflammatory activities in the rat brain.

The Role of ERK1/2 Pathway in the Pathophysiology of Alzheimer's Disease: An Overview and Update on New Developments

Alzheimer's disease (AD) is the most common neurodegenerative disorder worldwide. Several findings suggest that correcting the dysregulated signaling pathways may offer a potential therapeutic approach in this disease. Extracellular signal-regulated kinase 1/2 (ERK1/2), a member of the mitogen-activated protein kinase family, plays a major role in regulation of cell proliferation, autophagy process, and protein synthesis. The available literature suggests dysregulated ERK1/2 in AD patients with potential implications in the multifaceted underlying pathologies of AD, including amyloid-β plaque formation, tau phosphorylation, and neuroinflammation. In this regard, in the current review, we aim to summarize the reports on the potential roles of ERK1/2 in AD pathophysiology.

Diabetes: Risk factor and translational therapeutic implications for Alzheimer's disease

Type 2 diabetes mellitus (T2DM) and Alzheimer's disease (AD) commonly co-occur. T2DM increases the risk for AD by approximately twofold. Animal models provide one means of interrogating the relationship of T2DM to AD and investigating brain insulin resistance in the pathophysiology of AD. Animal models show that persistent hyperglycaemia results in chronic low-grade inflammation that may contribute to the development of neuroinflammation and accelerate the pathobiology of AD. Epidemiological studies suggest that patients with T2DM who received treatment with specific anti-diabetic agents have a decreased risk for the occurrence of AD and all-cause dementia. Agents such as metformin ameliorate T2DM and may have other important systemic effects that lower the risk of AD. Glucagon-like peptide 1 (GLP-1) agonists have been associated with a decreased risk for AD in patients with T2DM. Both insulin and non-insulin anti-diabetic treatments have been evaluated for the treatment of AD in clinical trials. In most cases, patients included in the trials have clinical features of AD but do not have T2DM. Many of the trials were conducted prior to the use of diagnostic biomarkers for AD. Trials have had a wide range of durations and population sizes. Many of the agents used to treat T2DM do not cross the blood brain barrier, and the effects are posited to occur via lowering of peripheral hyperglycaemia and reduction of peripheral and central inflammation. Clinical trials of anti-diabetic agents to treat AD are ongoing and will provide insight into the therapeutic utility of these agents.

Inhibition of phosphodiesterase: A novel therapeutic target for the treatment of mild cognitive impairment and Alzheimer's disease

Alzheimer's disease (AD) is the most common form of dementia and is ranked as the 6th leading cause of death in the US. The prevalence of AD and dementia is steadily increasing and expected cases in USA is 14.8 million by 2050. Neuroinflammation and gradual neurodegeneration occurs in Alzheimer's disease. However, existing medications has limitation to completely abolish, delay, or prevent disease progression. Phosphodiesterases (PDEs) are large family of enzymes to hydrolyze the 3'-phosphodiester links in cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP) in signal-transduction pathways for generation of 5'-cyclic nucleotides. It plays vital role to orchestrate several pharmacological activities for proper cell functioning and regulating the levels of cAMP and cGMP. Several evidence has suggested that abnormal cAMP signaling is linked to cognitive problems in neurodegenerative disorders like AD. Therefore, the PDE family has become a widely accepted and multipotential therapeutic target for neurodegenerative diseases. Notably, modulation of cAMP/cGMP by phytonutrients has a huge potential for the management of AD. Natural compounds have been known to inhibit phosphodiesterase by targeting key enzymes of cGMP synthesis pathway, however, the mechanism of action and their therapeutic efficacy has not been explored extensively. Currently, few PDE inhibitors such as Vinpocetine and Nicergoline have been used for treatment of central nervous system (CNS) disorders. Considering the role of flavonoids to inhibit PDE, this review discussed the therapeutic potential of natural compounds with PDE inhibitory activity for the treatment of AD and related dementia.

Preventive effects of arctigenin from Arctium lappa L against LPS-induced neuroinflammation and cognitive impairments in mice

Arctigenin (Arc) is a phenylpropanoid dibenzylbutyrolactone lignan in Arctium lappa L, which has been widely applied as a traditional Chinese herbal medicine for treating inflammation. In the present study, we explored the neuroprotective effect and the potential mechanisms of arctigenin against LPS-evoked neuroinflammation, neurodegeneration, and memory impairments in the mice hippocampus. Daily administration of arctigenin (50 mg/kg per day, i.g.) for 28 days revealed noticeable improvements in spatial learning and memory deficits after exposure to LPS treatment. Arctigenin prevented LPS-induced neuronal/synaptic injury and inhibited the increases in Abeta (Aβ) generation and the levels of amyloid precursor protein (APP) and β-site amyloid precursor protein cleavage enzyme 1 (BACE1). Moreover, arctigenin treatment also suppressed glial activation and reduced the production of proinflammatory cytokines. In LPS-treated BV-2 microglial cells and mice, activation of the TLR4 mediated NF-κB signaling pathway was significantly suppressed by arctigenin administration. Mechanistically, arctigenin reduced the LPS-induced interaction of adiponectin receptor 1 (AdipoR1) with TLR4 and its coreceptor CD14 and inhibited the TLR4-mediated downstream inflammatory response. The outcomes of the current study indicate that arctigenin mitigates LPS-induced apoptotic neurodegeneration, amyloidogenesis and neuroinflammation as well as cognitive impairments, and suggest that arctigenin may be a potential therapeutic candidate for neuroinflammation/neurodegeneration-related diseases.

Lactobacillus Spp.-Enhanced Memory is Strain-Dependent and Associated, in Part, with Amyloidogenic and anti-Oxidant/Oxidative Stress Interplay in Amyloid Beta Precursor Protein Transgenic Mice

This study explored mechanisms underpinning enhanced memory in amyloid precursor protein (APP) transgenic mice (male; 10-12 months; n = 6/group) supplemented with Lactobacillus plantarum LAB12 (LAB12)/Lactobacillus casei Shirota (LcS). Morris Water Maze test was performed before brains were harvested for gene expression and biochemical studies. LAB-supplemented mice exhibited reduced escape latency and distance but significant increased time spent in platform zone. This was associated with downregulated beta-site APP cleaving enzyme-1 (BACE1) mRNA and significant reduced nitric oxide in brains. LAB12 also significantly increased glutathione. The LAB-enhanced memory is strain-dependent and could be mediated, in part, through amyloidogenic pathway and anti-oxidant/oxidative stress interplay.

Flavonoid Derivatives as Potential Cholinesterase Inhibitors in Scopolamine-Induced Amnesic Mice: An In Vitro, In Vivo and Integrated Computational Approach

Flavonoids are one of the most exciting types of phenolic compounds with a wide range of bioactive benefits. A series of flavone derivatives (F1–F5) were previously synthesized from substituted O-hydroxy acetophenone and substituted chloro-benzaldehydes. The titled compounds F1–F5 in the present study were evaluated for their anticholinesterase potential (against AChE and BuChE). The obtained results were then validated through a molecular docking approach. Compound F5 was found to be the most potent inhibitor of AChE (IC₅₀ = 98.42 ± 0.97 µg/mL) followed by compound F4, whereas compound F2 was found to be the most promising inhibitor of BuChE (IC₅₀ = 105.20 ± 1.43 µg/mL) among the tested compounds. The molecular docking analysis revealed a similar trend in the binding affinity of compounds with the targeted enzymes and found them to be capable of forming highly stable complexes with both receptors. The selected compounds were further subjected to in vivo assessment of cognitive function in a scopolamine-induced amnesic animal model, in which almost all compounds F1–F5 significantly attenuated the amnesic effects as evaluated through Y-Maze Paradigm and novel object discrimination (NOD) tasks, findings that were further supported by ex vivo experimental results. Among (F1–F5), F5 showed significant anti-amnesic effects in scopolamine-induced amnesic models and ameliorated the memory loss in behavioral model studies as compared to counterparts. In ex vivo study, noteworthy protection from oxidative stress in the brains of scopolamine-induced amnesic mice was also recorded for F5. These findings also confirmed that there were no significant differences among the in vivo and ex vivo results after administration of F1–F5 (7.5 or 15 mg/kg) or donepezil (2 mg/kg). These synthesized flavonoids could serve as potential candidates for new neuroprotective and nootropic drugs. However, further studies are needed to validate their observed potential in other animal models as well.

New Paradigm in Cell Therapy Using Sperm Head to Restore Brain Function and Structure in Animal Model of Alzheimer’s Disease: Support for Boosting Constructive Inflammation vs. Anti-Inflammatory Approach

Alzheimer’s is characterized by accumulation of amyloid-β (Aβ) associated with insufficient clearance of toxicants from the brain establishing a chronic inflammation and other abnormalities in the brain. Inflammatory microglia and astrocytes along with abnormal lymphatics associated with insufficient clearance of Aβ and other toxicants from the brain establish a chronic inflammation. This causes abnormal choroid plexus, leukocyte trafficking, and hypoxic condition along with high levels of regulatory T cells (Tregs). There is no consensus among researchers regarding decreasing or increasing Tregs to achieve therapeutic effects. Different opposing studies tried to suppress or boost inflammation to treat AD. Based on reproductive immunology, sperm induces constructive inflammatory response and seminal-vesicle-fluid (SVF) suppresses inflammation leading to uterus remodeling. It prompted us to compare therapeutic efficiency of inflammatory or anti-inflammatory approaches in AD model based on reproductive immunology. To do so, SVF, sperm, or sperm head (from Wistar rat) was administered via intra-cerebro-ventricular route to Sprague Dawley rat AD model. Behavioral and histological examination were made and treatment groups were compared with control AD model and normal groups. Therapeutic efficacy was in the order of sperm head>sperm>SVF. Sperm head returned learning memory, Aβ, lymphatics, neural growth factors, choroid plexus function, Iba-1/GFAP, MHC II/CD86/CD40, CD38/IL-10, and hypoxia levels back to normal level. However, SVF just partially ameliorated the disease. Immunologic properties of sperm/sperm head to elicit constructive inflammation can be extended to organs other than reproductive. This nature-based approach overcomes genetic difference as an important obstacle and limitation in cell therapy, and is expected to be safe or with least side effects.

Effects of Rosemary Oil (Rosmarinus officinalis) supplementation on the fate of the transplanted human olfactory bulb neural stem cells against ibotenic acid-induced neurotoxicity (Alzheimer model) in rat

Rosemary oil (ROO) is known to have multiple pharmacological effects: it is an antioxidant, anti-inflammatory, and cytoprotective. In the present study, we examined the effects of ROO on Human olfactory bulb neuronal stem cells (hOBNSCs) after their transplantation into rats, with the ibotenic (IBO) acid-induced cognitive deficit model. After 7 weeks, cognitive functions were assessed using the Morris water maze (MWM). After two months blood and hippocampus samples were collected for biochemical, gene expression, and histomorphometric analyses. Learning ability and memory function were significantly enhanced (P < 0.05) after hOBNSCs transplantation and were nearly returned to normal in the treated group. The IBO acid injection was associated with a significant decline (P < 0.05) of total leukocyte count (TLC) and a significant increase (P < 0.05) in total and toxic neutrophils. As well, the level of IL-1β, TNF-α CRP in serum and levels of MDA and NO in hippocampus tissue were significantly elevated (P < 0.05), while antioxidant markers (CAT, GSH, and SOD) were reduced (P < 0.05) in treated tissue compared to controls. The administration of ROO before or with cell transplantation attenuated all these parameters. In particular, the level of NO nearly returned to normal when rosemary was administrated before cell transplantation. Gene expression analysis revealed the potential protective effect of ROO and hOBNSCs via down-expression of R-βAmyl and R- CAS 3 and R-GFAP genes. The improvement in the histological organization of the hippocampus was detected after the hOBNSCs transplantation especially in h/ROO/hOBNSCs group.

Pharmacological considerations for treating neuroinflammation with curcumin in Alzheimer's disease

Prof. Dr. Peter Riederer, the former Head of the Neurochemistry Department of the Psychiatry and Psychotherapy Clinic at the University of Würzburg (Germany), has been one of the pioneers of research into oxidative stress in Parkinson's and Alzheimer's disease (AD). This review will outline how his scientific contribution to the field has opened a new direction for AD treatment beyond "plaques and tangles". In the 1990s, Prof. Riederer was one of the first scientists who proposed oxidative stress and neuroinflammation as one of the major contributors to Alzheimer's disease, despite the overwhelming support for the "amyloid-only" hypothesis at the time, which postulated that the sole and only cause of AD is β-amyloid. His group also highlighted the role of advanced glycation end products, sugar and dicarbonyl-derived protein modifications, which crosslink proteins into insoluble aggregates and potent pro-inflammatory activators of microglia. For the treatment of chronic neuroinflammation, he and his group suggested that the most appropriate drug class would be cytokine-suppressive anti-inflammatory drugs (CSAIDs) which have a broader anti-inflammatory action range than conventional non-steroidal anti-inflammatory drugs. One of the most potent CSAIDs is curcumin, but it suffers from a variety of pharmacokinetic disadvantages including low bioavailability, which might have tainted many human clinical trials. Although a variety of oral formulations with increased bioavailability have been developed, curcumin's absorption after oral delivery is too low to reach therapeutic concentrations in the micromolar range in the systemic circulation and the brain. This review will conclude with evidence that rectally applied suppositories might be the best alternatives to oral medications, as this route will be able to evade first-pass metabolism in the liver and achieve high concentrations of curcumin in plasma and tissues, including the brain.

Pharmacological Mechanisms and Clinical Applications of Curcumin: Update

Curcumin, a well-known hydrophobic polyphenol extracted from the rhizomes of turmeric (Curcuma longa L.), has attracted great interest in the last ten years due to its multiple pharmacological activities. A growing body of evidence has manifested that curcumin has extensive pharmacological activities including anti-inflammatory, anti-oxygenation, lipid regulation, antiviral, and anticancer with hypotoxicity and minor adverse reactions. However, the disadvantages of low bioavailability, short half-life in plasma, low drug concentration in blood, and poor oral absorption severely limited the clinical application of curcumin. Pharmaceutical researchers have carried out plenty of dosage form transformations to improve the druggability of curcumin and have achieved remarkable results. Therefore, the objective of this review summarizes the pharmacological research progress, problems in clinical application and the improvement methods of curcumin's druggability. By reviewing the latest research progress of curcumin, we believe that curcumin has a broad clinical application prospect for its wide range of pharmacological activities with few side effects. The deficiencies of lower bioavailability of curcumin could be improved by dosage form transformation. However, curcumin in the clinical application still requires further study regarding the underlying mechanism and clinical trial verification.

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.

Beta Amyloid, Tau Protein, and Neuroinflammation: An Attempt to Integrate Different Hypotheses of Alzheimer’s Disease Pathogenesis

Abstract

Alzheimer’s disease (AD) is a neurodegenerative disease that inevitably results in dementia and death. Currently, there are no pathogenetically grounded methods for the prevention and treatment of AD, and all current treatment regimens are symptomatic and unable to significantly delay the development of dementia. The accumulation of β-amyloid peptide (Aβ), which is a spontaneous, aggregation-prone, and neurotoxic product of the processing of signaling protein APP (Amyloid Precursor Protein), in brain tissues, primarily in the hippocampus and the frontal cortex, was for a long time considered the main cause of neurodegenerative changes in AD. However, attempts to treat AD based on decreasing Aβ production and aggregation did not bring significant clinical results. More and more arguments are arising in favor of the fact that the overproduction of Aβ in most cases of AD is not the initial cause, but a concomitant event of pathological processes in the course of the development of sporadic AD. The concept of neuroinflammation has come to the fore, suggesting that inflammatory responses play the leading role in the initiation and development of AD, both in brain tissue and in the periphery. The hypothesis about the key role of neuroinflammation in the pathogenesis of AD opens up new opportunities in the search for ways to treat and prevent this socially significant disease.

Recent Advances in the Anti-Inflammatory Activity of Plant-Derived Alkaloid Rhynchophylline in Neurological and Cardiovascular Diseases

Rhynchophylline (Rhy) is a plant-derived indole alkaloid isolated from Uncaria species. Both the plant and the alkaloid possess numerous protective properties such as anti-inflammatory, neuroprotective, anti-hypertensive, anti-rhythmic, and sedative effects. Several studies support the significance of the anti-inflammatory activity of the plant as an underlying mechanism for most of the pharmacological activities of the alkaloid. Rhy is effective in protecting both the central nervous system and cardiovascular system. Cerebro-cardiovascular disease primarily occurs due to changes in lifestyle habits. Many previous studies have highlighted the significance of Rhy in modulating calcium channels and potassium channels, thereby protecting the brain from neurodegenerative diseases and related effects. Rhy also has anticoagulation and anti-platelet aggregation activity. Although Rhy has displayed its role in protecting the cardiovascular system, very little is explored about its intervention in early atherosclerosis. Extensive studies are required to understand the cardioprotective effects of Rhye. This review summarized and discussed the various pharmacological effects of Rhy in neuro- and cardioprotection and in particular the relevance of Rhy in preventing early atherosclerosis using Rhy-loaded nanoparticles.

Anti-Neuroinflammatory Potential of Polyphenols by Inhibiting NF-κB to Halt Alzheimer's Disease

Alzheimer's disease (AD) is an irrevocable chronic brain disorder featured by neuronal loss, microglial accumulation, and progressive cognitive impairment. The proper pathophysiology of this life-threatening disorder is not completely understood and no exact remedies have been found yet. Over the last few decades, research on AD has mainly highlighted pathomechanisms linked to a couple of the major pathological hallmarks, including extracellular senile plaques made of amyloid-β (Aβ) peptides, and intracellular neurofibrillary tangles (NFTs) made of tau proteins. Aβ can induce apoptosis, trigger an inflammatory response, and inhibit the synaptic plasticity of the hippocampus, which ultimately contributes to reducing cognitive functions and memory impairment. Recently, a third disease hallmark, the neuroinflammatory reaction that is mediated by cerebral innate immune cells, has become a spotlight in the current research area, assured by pre-clinical, clinical, and genetic investigations. Nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), a cytokine producer, is significantly associated with physiological inflammatory proceedings and thus shows a promising candidate for inflammation- based AD therapy. Recent data reveal that phytochemicals, mainly polyphenol compounds, exhibit potential neuroprotective functions and these may be considered as a vital resource for discovering several drug candidates against AD. Interestingly, phytochemicals can easily interfere with the signaling pathway of NF-κB. This review represents the anti-neuroinflammatory potential of polyphenols as inhibitors of NF-κB to combat AD pathogenesis.

Electronegative very-low-density lipoprotein induces brain inflammation and cognitive dysfunction in mice

Epidemiologic studies have indicated that dyslipidemia may facilitate the progression of cognitive dysfunction. We previously showed that patients with metabolic syndrome (MetS) had significantly higher plasma levels of electronegative very-low-density lipoprotein (VLDL) than did healthy controls. However, the effects of electronegative-VLDL on the brain and cognitive function remain unclear. In this study, VLDL isolated from healthy volunteers (nVLDL) or patients with MetS (metVLDL) was administered to mice by means of tail vein injection. Cognitive function was assessed by using the Y maze test, and plasma and brain tissues were analyzed. We found that mice injected with metVLDL but not nVLDL exhibited significant hippocampus CA3 neuronal cell loss and cognitive dysfunction. In mice injected with nVLDL, we observed mild glial cell activation in the medial prefrontal cortex (mPFC) and hippocampus CA3. However, in mice injected with metVLDL, plasma and brain TNF-α and Aβ-42 levels and glial cell activation in the mPFC and whole hippocampus were higher than those in control mice. In conclusion, long-term exposure to metVLDL induced levels of TNF-α, Aβ-42, and glial cells in the brain, contributing to the progression of cognitive dysfunction. Our findings suggest that electronegative-VLDL levels may represent a new therapeutic target for cognitive dysfunction.

Role of natural products for the treatment of Alzheimer's disease

Negative psychological and physiological consequences of neurodegenerative disorders represent a high social and health cost. Among the neurodegenerative disorders Alzheimer's disease (AD) is recognized as a leading neurodegenerative condition and a primary cause of dementia in the elderlys. AD is considered as neurodegenerative disorder that progressively impairs cognitive function and memory. According to current epidemiological data, about 50 milLion people worldwide are suffering from AD. The primary symptoms of AD are almost inappreciable and usually comprise forgetfulness of recent events. Numerous processes are involved in the development of AD, for example oxidative stress (OS) mainly due to mitochondrial dysfunction, intracellular the accumulation of hyperphosphorylated tau (τ) proteins in the form of neurofibrillary tangles, excessive the accumulation of extracellular plaques of beta-amyloid (Aβ), genetic and environmental factors. Running treatments only attenuate symptoms and temporarily reduce the rate of cognitive progression associated with AD. This means that most treatments focus only on controlLing symptoms, particularly in the initial stages of the disease. In the past, the first choice of treatment was based on natural ingredients. In this sense, diverse natural products (NPs) are capable to decrease the symptoms and alleviate the development of several diseases including AD attracting the attention of the scientific community and the pharmaceutical industry. Specifically, numerous NPs including flavonoids, gingerols, tannins, anthocyanins, triterpenes and alkaloids have been shown anti-inflammatory, antioxidant, anti-amyloidogenic, and anti-choLinesterase properties. This review provide a summary of the pathogenesis and the therapeutic goals of AD. It also discusses the available data on various plants and isolated natural compounds used to prevent and diminish the symptoms of AD.

TREM2 Mediates Microglial Anti-Inflammatory Activations in Alzheimer's Disease: Lessons Learned from Transcriptomics

Alzheimer’s disease (AD) is a lethal neurodegenerative disorder primarily affecting the aged population. The etiopathogenesis of AD, especially that of the sporadic type, remains elusive. The triggering receptor expressed on myeloid cells 2 (TREM2), a member of TREM immunoglobulin superfamily, plays a critical role in microglial physiology. Missense mutations in human TREM2 are determined as genetic risk factors associated with the development of sporadic AD. However, the roles of TREM2 in the pathogenesis of AD are still to be established. In this review, we outlined the influence of Trem2 on balance of pro- and anti-inflammatory microglial activations from a perspective of AD mouse model transcriptomics. On this basis, we further speculated the roles of TREM2 in different stages of AD, which may shed light to the development of TREM2-targeted strategy for the prevention and treatment of this neurodegenerative disorder.

Identification of tetragocarbone C and sideroxylin as the most potent anti-inflammatory components of Syncarpia glomulifera

In contrast to ancient Western and Asian cultures, medicinal plants of the Aboriginal and Torres Strait Islanders in Australia have not been as intensively studied for their molecular composition and molecular bioactivity. Syncarpia glomulifera subsp. glomulifera is a species in the plant family Myrtaceae. The resin of the plant has been traditionally used by the D'harawal people of Western Sydney to heal inflamed sores and ulcers. Hence, the anti-inflammatory activity of its leaf extract was investigated in RAW 264.7 macrophage and N11 microglia cell lines to isolate and identify the most active compounds. One new compound, tetragocarbone C, and three known compounds, tetragocarbone B, sideroxylin, and lumaflavanone A showed potent anti-inflammatory activity by downregulating nitric oxide and TNF-α production in LPS and IFN-γ stimulated cells. Except for the less potent tetragocarbone B, all compounds had an IC₅₀ value (for nitric oxide downregulation) of <10 μg/mL and moderate cytotoxicity in both cell lines. The molecular targets along pro-inflammatory signaling pathways were further investigated in RAW 264.7 cells. All four compounds suppressed phosphorylation of ERK, c-Jun, and limited the phosphorylation of STAT-1 and STAT-3 in response to LPS and IFN-γ activation. The four compounds also suppressed NF-κB activation by preventing the translocation of the p65 subunit into the nucleus. Collectively, these findings suggest that the compounds isolated from Syncarpia glomulifera, especially tetragocarbone C and sideroxylin are promising anti-inflammatory agents, and could be further investigated for the treatment of diseases characterized by chronic inflammation.

Anti-Cognitive Decline by Yinxing-Mihuan-Oral-Liquid via Activating CREB/BDNF Signaling and Inhibiting Neuroinflammatory Process

BACKGROUND: Cognitive decline in the normal aging process is one of the most common and prominent problems. Delaying and alleviating cognitive impairment is an important strategy of anti-aging. This study is to aim at investigating the effects of Yinxing-Mihuan-Oral-Liquid(GMOL) on the CREB/BDNF signaling in the normal aging process.METHODS: SD rats were randomly divided into GMOL group and control group. The Morris water maze (MWM) was introduced for behavioral test. Immunohistochemistry and immunofluorescence were used for cAMP response element binding protein 1(CREB1), p-CREB(Ser133), brain-derived neurotrophic factor(BDNF), synaptophysin(SYP) and glial fibrillary acidic protein(GFAP). Western blot was conducted for investigating the levels of CREB1 and p-CREB(Ser133), BDNF, SYP, GFAP and interleukin 6(IL-6). RESULTS:  Our data showed that compared with the control group, GMOL group had higher expression of memory-related proteins, decreased inflammatory factors, and enhanced spatial learning and memory ability.CONCLUSION: The study results show that GMOL ameliorates cognitive impairment of the normal aged SD rats via enhancing the expression of memory biomarkers and inhibiting inflammatory process. The potential neuroprotective role of GMOL in the process of aging may be related to mitigating cognitive decline via activating CREB/BDNF signaling and inhibiting inflammatory process.

Single Administration of the T-Type Calcium Channel Enhancer SAK3 Reduces Oxidative Stress and Improves Cognition in Olfactory Bulbectomized Mice

Alzheimer’s disease (AD), characterized by cognitive impairments, is considered to be one of the most widespread chronic neurodegenerative diseases worldwide. We recently introduced a novel therapeutic agent for AD treatment, the T-type calcium channel enhancer ethyl-8-methyl-2,4-dioxo-2-(piperidin-1-yl)-2H-spiro[cyclopentane-1,3-imidazo[1,2-a]pyridin]-2-ene-3-carboxylate (SAK3). SAK3 enhances calcium/calmodulin-dependent protein kinase II and proteasome activity, thereby promoting amyloid beta degradation in mice with AD. However, the antioxidative effects of SAK3 remain unclear. We investigated the antioxidative effects of SAK3 in olfactory bulbectomized mice (OBX mice), compared with the effects of donepezil as a positive control. As previously reported, single oral administration of both SAK3 (0.5 mg/kg, p.o.) and donepezil (1.0 mg/kg, p.o.) significantly improved cognitive and depressive behaviors in OBX mice. Single oral SAK3 administration markedly reduced 4-hydroxy-2-nonenal and nitrotyrosine protein levels in the hippocampus of OBX mice, which persisted until 1 week after administration. These effects are similar to those observed with donepezil therapy. Increased protein levels of oxidative stress markers were observed in the microglial cells, which were significantly rescued by SAK3 and donepezil. SAK3 could ameliorate oxidative stress in OBX mice, like donepezil, suggesting that the antioxidative effects of SAK3 and donepezil are among the neuroprotective mechanisms in AD pathogenesis.

Geissoschizoline, a promising alkaloid for Alzheimer's disease: Inhibition of human cholinesterases, anti-inflammatory effects and molecular docking

Due to the lack of effective pharmacotherapy options to treats Alzheimer's disease, new strategies have been approached in the search for multi-target molecules as therapeutic options. In this work, four indole alkaloids, geissoschizoline, geissoschizone, geissospermine, and 3',4',5',6'-tetradehydrogeissospermine were isolated from Geissospermum vellosii (Pao pereira) and evaluated for their anticholinesterase activities. While geissospermine inhibited only butyrylcholinesterase (BChE), the other alkaloids behaved as non-selective inhibitors of acetylcholinesterase (AChE) and BChE. In cell viability tests, only geissoschizoline was not cytotoxic. Therefore, geissoschizoline actions were also evaluated in human cholinesterases, where it was twice as potent inhibitor of hBChE (IC₅₀ = 10.21 ± 0.01 µM) than hAChE (IC₅₀ = 20.40 ± 0.93 µM). On enzyme kinetic studies, geissoschizoline presented a mixed-type inhibition mechanism for both enzymes. Molecular docking studies pointed interactions of geissoschizoline with active site and peripheral anionic site of hAChE and hBChE, indicating a dual site inhibitor profile. Moreover, geissoschizoline also played a promising anti-inflammatory role, reducing microglial release of NO and TNF-α at a concentration (1 μM) ten and twenty times lower than the IC₅₀ values of hBChE and hAChE inhibition, respectively. These actions give geissoschizoline a strong neuroprotective character. In addition, the ability to inhibit hAChE and hBChE, with approximate inhibitory potencies, accredits this alkaloid for therapeutic use in the moderate to severe phase of AD. Thus, geissoschizoline emerges as a possible multi-target prototype that can be very useful in preventing neurodegeneration and restore neurotransmission.

Apigenin Modulates Dendritic Cell Activities and Curbs Inflammation Via RelB Inhibition in the Context of Neuroinflammatory Diseases

Neuroinflammation leads to tissue injury causing many of the clinical symptoms of Multiple Sclerosis, an autoimmune disorder of the central nervous system (CNS). While T cells, specifically T_h1 and T_h17 cells, are the ultimate effectors of this disease, dendritic cells (DCs) mediate T cell polarization, activation, etc. In our previous study, Apigenin, a natural flavonoid, has been shown to reduce EAE disease severity through amelioration of demyelination in the CNS as well as the sequestering of DCs and other myeloid cells in the periphery. Here, we show that Apigenin exerts its effects possibly through shifting DC modulated T cell responses from T_h1 and T_h17 type towards T_reg directed responses evident through the decrease in T-bet, IFN-γ (T_h1), IL-17 (T_h17) and increase in IL-10, TGF-β and FoxP3 (T_reg) expression in cells from both normal human donors and EAE mice. RelB, an NF-κβ pathway protein is central to DC maturation, its antigen presentation capabilities and DC-mediated T cell activation. Apigenin reduced mRNA and protein levels of RelB and also reduced its nuclear translocation. Additionally, siRNA-mediated silencing of RelB further potentiated the RelB-mediated effects of Apigenin thus confirming its role in Apigenin directed regulation of DC biology. These results provide key information about the molecular events controlled by Apigenin in its regulation of DC activity marking its potential as a therapy for neuroinflammatory disease. Graphical Abstract.

Hypothalamic Neuropeptide Brain Protection: Focus on Oxytocin

Oxytocin (OXT) is hypothalamic neuropeptide synthetized in the brain by magnocellular and parvo cellular neurons of the paraventricular (PVN), supraoptic (SON) and accessory nuclei (AN) of the hypothalamus. OXT acts in the central and peripheral nervous systems via G-protein-coupled receptors. The classical physiological functions of OXT are uterine contractions, the milk ejection reflex during lactation, penile erection and sexual arousal, but recent studies have demonstrated that OXT may have anti-inflammatory and anti-oxidant properties and regulate immune and anti-inflammatory responses. In the pathogenesis of various neurodegenerative diseases, microglia are present in an active form and release high levels of pro-inflammatory cytokines and chemokines that are implicated in the process of neural injury. A promising treatment for neurodegenerative diseases involves new therapeutic approaches targeting activated microglia. Recent studies have reported that OXT exerts neuroprotective effects through the inhibition of production of pro-inflammatory mediators, and in the development of correct neural circuitry. The focus of this review is to attribute a new important role of OXT in neuroprotection through the microglia–OXT interaction of immature and adult brains. In addition, we analyzed the strategies that could enhance the delivery of OXT in the brain and amplify its positive effects.

3'Pool-seq: an optimized cost-efficient and scalable method of whole-transcriptome gene expression profiling

BACKGROUND

The advent of Next Generation Sequencing has allowed transcriptomes to be profiled with unprecedented accuracy, but the high costs of full-length mRNA sequencing have posed a limit on the accessibility and scalability of the technology. To address this, we developed 3'Pool-seq: a simple, cost-effective, and scalable RNA-seq method that focuses sequencing to the 3'-end of mRNA. We drew from aspects of SMART-seq, Drop-seq, and TruSeq to implement an easy workflow, and optimized parameters such as input RNA concentrations, tagmentation conditions, and read depth specifically for bulk-RNA.

RESULTS

Thorough optimization resulted in a protocol that takes less than 12 h to perform, does not require custom sequencing primers or instrumentation, and cuts over 90% of the costs associated with TruSeq, while still achieving accurate gene expression quantification (Pearson's correlation coefficient with ERCC theoretical concentration r = 0.96) and differential gene detection (ROC analysis of 3'Pool-seq compared to TruSeq AUC = 0.921). The 3'Pool-seq dual indexing scheme was further adapted for a 96-well plate format, and ERCC spike-ins were used to correct for potential row or column pooling effects. Transcriptional profiling of troglitazone and pioglitazone treatments at multiple doses and time points in HepG2 cells was then used to show how 3'Pool-seq could distinguish the two molecules based on their molecular signatures.

CONCLUSIONS

3'Pool-seq can accurately detect gene expression at a level that is on par with TruSeq, at one tenth of the total cost. Furthermore, its unprecedented TruSeq/Nextera hybrid indexing scheme and streamlined workflow can be applied in several different formats, including 96-well plates, which allows users to thoroughly evaluate biological systems under several conditions and timepoints. Care must be taken regarding experimental design and plate layout such that potential pooling effects can be accounted for and corrected. Lastly, further studies using multiple sets of ERCC spike-ins may be used to simulate differential gene expression in a system with known ground-state values.

Deferiprone and efonidipine mitigated iron-overload induced neurotoxicity in wild-type and thalassemic mice

AIMS

We previously demonstrated that iron-overload in non-thalassemic rats induced neurotoxicity and cognitive decline. However, the effect of iron-overload on the brain of thalassemic condition has never been investigated. An iron chelator (deferiprone) provides neuroprotective effects against metal toxicity. Furthermore, a T-type calcium channels blocker (efonidipine) effectively attenuates cardiac dysfunction in thalassemic mice with iron-overload. However, the effects of both drugs on brain of iron-overload thalassemia has not been determined. We hypothesize that iron-overload induces neurotoxicity in Thalassemic and wild-type mice, and not only deferiprone, but also efonidipine, provides neuroprotection against iron-overload condition.

MAIN METHODS

Mice from both wild-type (WT) and β-thalassemic type (HT) groups were assigned to be fed with a standard-diet or high-iron diet containing 0.2% ferrocene/kg of diet (HFe) for 4 months consecutively. After three months of HFe, 75-mg/kg/d deferiprone or 4-mg/kg/d efonidipine were administered to the HFe-fed WT and HT mice for 1 month.

KEY FINDINGS

HFe consumption caused an equal impact on circulating iron-overload, oxidative stress, and inflammation in WT and HT mice. Brain iron-overload and iron-mediated neurotoxicity, such as oxidative stress, inflammation, glial activation, mitochondrial dysfunction, and Alzheimer's like pathologies, were observed to an equal degree in HFe fed WT and HT mice. These pathological conditions were mitigated by both deferiprone and efonidipine.

SIGNIFICANCE

These findings indicate that iron-overload itself caused neurotoxicity, and T-type calcium channels may play a role in this condition.

Chemotherapy accelerates age-related development of tauopathy and results in loss of synaptic integrity and cognitive impairment

Cancer and its treatment are associated with neurotoxic side effects, including cognitive dysfunction, altered functional connectivity in the brain and structural abnormalities in white matter. There is evidence that cancer and its treatment can accelerate aging. Tau is a microtubule associated protein that contributes to microtubule stability thereby playing a key role in neuronal function. Clustering of tau is commonly observed in the aged brain and is related to cognitive decline. We hypothesized that chemotherapy-induced cognitive impairment is associated with accelerated development of tau clustering in the brain as a sign of accelerated aging. We show for the first time that treatment of adult (7-8 month-old) male C57BL/6 mice with cisplatin results in reduced cognitive function and a marked increase in the number of large endogenous tau clusters in the hippocampus when assessed 4 months later. In contrast, we detected only few small tau clusters in the hippocampus of age-matched 11-12 month-old control mice. Astrocyte GFAP expression was increased in close vicinity to the tau clusters in cisplatin-treated mice. We did not detect changes in the microglial marker Iba-1 in the brain of mice treated with cisplatin. The accelerated formation of Tau-1 clusters in cisplatin-treated mice was associated with a decrease in the levels of the post-synaptic marker PSD95 and of the presynaptic marker synaptophysin in the hippocampus. We demonstrate here for the first time that chemotherapy markedly accelerates development of signs of tauopathy and loss of synaptic integrity in the hippocampus. These findings provide a mechanistic link between chemotherapy cognitive decline and accelerated aging in cancer survivors.

Astrocyte alterations in neurodegenerative pathologies and their modeling in human induced pluripotent stem cell platforms

Astrocytes are the most abundant cell type in the brain. They were long considered only as passive support for neuronal cells. However, recent data have revealed many active roles for these cells both in maintenance of the normal physiological homeostasis in the brain as well as in neurodegeneration and disease. Moreover, human astrocytes have been found to be much more complex than their rodent counterparts, and to date, astrocytes are known to actively participate in a multitude of processes such as neurotransmitter uptake and recycling, gliotransmitter release, neuroenergetics, inflammation, modulation of synaptic activity, ionic balance, maintenance of the blood-brain barrier, and many other crucial functions of the brain. This review focuses on the role of astrocytes in human neurodegenerative disease and the potential of the novel stem cell-based platforms in modeling astrocytic functions in health and in disease.

Gut Microbiota Disorder, Gut Epithelial and Blood-Brain Barrier Dysfunctions in Etiopathogenesis of Dementia: Molecular Mechanisms and Signaling Pathways

Emerging evidences indicate a critical role of the gut microbiota in etiopathogenesis of dementia, a debilitating multifactorial disorder characterized by progressive deterioration of cognition and behavior that interferes with the social and professional functions of the sufferer. Available data suggest that gut microbiota disorder that triggers development of dementia is characterized by substantial reduction in specific species belonging to the Firmicutes and Bacteroidetes phyla and presence of pathogenic species, predominantly, pro-inflammatory bacteria of the Proteobacteria phylum. These changes in gut microbiota microecology promote the production of toxic metabolites and pro-inflammatory cytokines, and reduction in beneficial substances such as short chain fatty acids and other anti-inflammatory factors, thereby, enhancing destruction of the gut epithelial barrier with concomitant activation of local and distant immune cells as well as dysregulation of enteric neurons and glia. This subsequently leads to blood-brain barrier dysfunctions that trigger neuroinflammatory reactions and predisposes to apoptotic neuronal and glial cell death, particularly in the hippocampus and cerebral cortex, which underlie the development of dementia. However, the molecular switches that control these processes in the histo-hematic barriers of the gut and brain are not exactly known. This review integrates very recent data on the molecular mechanisms that link gut microbiota disorder to gut epithelial and blood-brain barrier dysfunctions, underlying the development of dementia. The signaling pathways that link gut microbiota disorder with impairment in cognition and behavior are also discussed. The review also highlights potential therapeutic options for dementia.

Targeting Inflammatory Pathways in Alzheimer's Disease: A Focus on Natural Products and Phytomedicines

Studies of the brains of Alzheimer's disease (AD) patients have revealed key neuropathological features, such as the deposition of aggregates of insoluble amyloid-β (Aβ) peptides and neurofibrillary tangles (NFTs). These pathological protein deposits, including Aβ peptides (which form senile plaques) and hyperphosphorylated tau (which aggregates into NFTs), have been assumed to be 'the cause of AD'. Aβ has been extensively targeted to develop an effective disease-modifying therapy, but with limited clinical success. Emerging therapies are also now targeting further pathological processes in AD, including neuroinflammation. This review focuses on the inflammatory and oxidative stress-related changes that occur in AD, and discusses some emerging anti-inflammatory natural products and phytomedicines. Many of the promising compounds are cytokine-suppressive anti-inflammatory drugs (CSAIDs), which target the proinflammatory AP1 and nuclear factor-κB signalling pathways and inhibit the expression of many proinflammatory cytokines, such as interleukin (IL)-1, IL-6, tumour necrosis factor-α, or nitric oxide produced by inducible nitric oxide synthase. However, many of these phytomedicines have not been tested in rigorous clinical trials in AD patients. It is not yet clear if the active compounds reach an effective concentration in the brain (due to limited bioavailability) or if they can slow down AD progression in long-term trials. The authors suggest that it is crucial for both the pharmacological and complementary medicine industries to conduct and fund those studies to significantly advance the field.

The Therapeutic Potential of Apigenin

Several plant bioactive compounds have exhibited functional activities that suggest they could play a remarkable role in preventing a wide range of chronic diseases. The largest group of naturally-occurring polyphenols are the flavonoids, including apigenin. The present work is an updated overview of apigenin, focusing on its health-promoting effects/therapeutic functions and, in particular, results of in vivo research. In addition to an introduction to its chemistry, nutraceutical features have also been described. The main key findings from in vivo research, including animal models and human studies, are summarized. The beneficial indications are reported and discussed in detail, including effects in diabetes, amnesia and Alzheimer's disease, depression and insomnia, cancer, etc. Finally, data on flavonoids from the main public databases are gathered to highlight the apigenin's key role in dietary assessment and in the evaluation of a formulated diet, to determine exposure and to investigate its health effects in vivo.

A Review and Hypothesized Model of the Mechanisms That Underpin the Relationship Between Inflammation and Cognition in the Elderly

Age is associated with increased risk for several disorders including dementias, cardiovascular disease, atherosclerosis, obesity, and diabetes. Age is also associated with cognitive decline particularly in cognitive domains associated with memory and processing speed. With increasing life expectancies in many countries, the number of people experiencing age-associated cognitive impairment is increasing and therefore from both economic and social terms the amelioration or slowing of cognitive aging is an important target for future research. However, the biological causes of age associated cognitive decline are not yet, well understood. In the current review, we outline the role of inflammation in cognitive aging and describe the role of several inflammatory processes, including inflamm-aging, vascular inflammation, and neuroinflammation which have both direct effect on brain function and indirect effects on brain function via changes in cardiovascular function.

Current Perspectives and Mechanisms of Relationship between Intestinal Microbiota Dysfunction and Dementia: A Review

BACKGROUND

Accumulating data suggest a crucial role of the intestinal microbiota in the development and progression of neurodegenerative diseases. More recently, emerging reports have revealed an association between intestinal microbiota dysfunctions and dementia, a debilitating multifactorial disorder, characterized by progressive deterioration of cognition and behavior that interferes with the social and professional life of the sufferer. However, the mechanisms of this association are not fully understood.

SUMMARY

In this review, I discuss recent data that suggest mechanisms of cross-talk between intestinal microbiota dysfunction and the brain that underlie the development of dementia. Potential therapeutic options for dementia are also discussed. The pleiotropic signaling of the metabolic products of the intestinal microbiota together with their specific roles in the maintenance of both the intestinal and blood-brain barriers as well as regulation of local, distant, and circulating immunocytes, and enteric, visceral, and central neural functions are integral to a healthy gut and brain.

KEY MESSAGES

Research investigating the effect of intestinal microbiota dysfunctions on brain health should focus on multiple interrelated systems involving local and central neuroendocrine, immunocyte, and neural signaling of microbial products and transmitters and neurohumoral cells that not only maintain intestinal, but also blood brain-barrier integrity. The change in intestinal microbiome/dysbiome repertoire is crucial to the development of dementia.

Current Perspectives regarding Stem Cell-Based Therapy for Alzheimer's Disease

Alzheimer's disease (AD), a progressive neurodegenerative disorder featuring memory loss and cognitive impairment, is caused by synaptic failure and the excessive accumulation of misfolded proteins. Many unsuccessful attempts have been made to develop new small molecules or antibodies to intervene in the disease's pathogenesis. Stem cell-based therapies cast a new hope for AD treatment as a replacement or regeneration strategy. The results from recent preclinical studies regarding stem cell-based therapies are promising. Human clinical trials are now underway. However, a number of questions remain to be answered prior to safe and effective clinical translation. This review explores the pathophysiology of AD and summarizes the relevant stem cell research according to cell type. We also briefly summarize related clinical trials. Finally, future perspectives are discussed with regard to their clinical applications.

Exosomes: a novel therapeutic target for Alzheimer's disease?

Extracellular exosomes are formed inside the cytoplasm of cells in compartments known as multivesicular bodies. Thus, exosomes contain cytoplasmic content. Multivesicular bodies fuse with the plasma membrane and release exosomes into the extracellular environment. Comprehensive research suggests that exosomes act as both inflammatory intermediaries and critical inducers of oxidative stress to drive progression of Alzheimer's disease. An important role of exosomes in Alzheimer's disease includes the formation of neurofibrillary tangles and beta-amyloid production, clearance, and accumulation. In addition, exosomes are involved in neuroinflammation and oxidative stress, which both act as triggers for beta-amyloid pathogenesis and tau hyperphosphorylation. Further, it has been shown that exosomes are strongly associated with beta-amyloid clearance. Thus, effective measures for regulating exosome metabolism may be novel drug targets for Alzheimer's disease.