Clinical utility of neuroprotective agents in neurodegenerative diseases: current status of drug development for Alzheimer's, Parkinson's and Huntington's diseases, and amyotrophic lateral sclerosis

Advances in Alzheimer's disease: A multifaceted review of potential therapies and diagnostic techniques for early detection

Alzheimer's disease (AD) remains one of the most formidable neurological disorders, affecting millions globally. This review provides a holistic overview of the therapeutic strategies, both conventional and novel, aimed at mitigating the impact of AD. Initially, we delve into the conventional approach, emphasizing the role of Acetylcholinesterase (AChE) inhibition, which has been a cornerstone in AD management. As our understanding of AD evolves, several novel potential approaches emerge. We discuss the promising roles of Butyrylcholinesterase (BChE) inhibition, Tau Protein inhibitors, COX-2 inhibition, PPAR-γ agonism, and FAHH inhibition, among others. The potential of the endocannabinoids (eCB) system, cholesterol-lowering drugs, metal chelators, and MMPs inhibitors are also explored, culminating in the exploration of the pivotal role of microRNA in AD progression. Parallel to these therapeutic insights, we shed light on the novel tools and methodologies revolutionizing AD research. From the quantitative analysis of gene expression by qRTPCR to the evaluation of mitochondrial function using induced pluripotent stem cells (iPSCs), the advances in diagnostic and research tools offer renewed hope. Moreover, we explore the current landscape of clinical trials, highlighting the leading drug interventions and their respective stages of development. This comprehensive review concludes with a look into the future perspectives, capturing the potential breakthroughs and innovations on the horizon. Through a synthesis of current knowledge and emerging research, this article aims to provide a consolidated resource for clinicians, researchers, and academicians in the realm of Alzheimer's disease.

Inhibition of Protein Aggregation and Endoplasmic Reticulum Stress as a Targeted Therapy for α-Synucleinopathy

α-synuclein (α-syn) is an intrinsically disordered protein abundant in the central nervous system. Physiologically, the protein regulates vesicle trafficking and neurotransmitter release in the presynaptic terminals. Pathologies related to misfolding and aggregation of α-syn are referred to as α-synucleinopathies, and they constitute a frequent cause of neurodegeneration. The most common α-synucleinopathy, Parkinson's disease (PD), is caused by abnormal accumulation of α-syn in the dopaminergic neurons of the midbrain. This results in protein overload, activation of endoplasmic reticulum (ER) stress, and, ultimately, neural cell apoptosis and neurodegeneration. To date, the available treatment options for PD are only symptomatic and rely on dopamine replacement therapy or palliative surgery. As the prevalence of PD has skyrocketed in recent years, there is a pending issue for development of new disease-modifying strategies. These include anti-aggregative agents that target α-syn directly (gene therapy, small molecules and immunization), indirectly (modulators of ER stress, oxidative stress and clearance pathways) or combine both actions (natural compounds). Herein, we provide an overview on the characteristic features of the structure and pathogenic mechanisms of α-syn that could be targeted with novel molecular-based therapies.

Molecular docking/dynamics simulations, MEP analysis, bioisosteric replacement and ADME/T prediction for identification of dual targets inhibitors of Parkinson's disease with novel scaffold

Monoamine oxidase B and Adenosine A2A receptors are used as key targets for Parkinson's disease. Recently, hMAO-B and hA2AR Dual-targets inhibitory potential of a novel series of Phenylxanthine derivatives has been established in experimental findings. Hence, the current study examines the interactions between 38 compounds of this series with hMAO-B and hA2AR targets using different molecular modeling techniques to investigate the binding mode and stability of the formed complexes. A molecular docking study revealed that the compounds L24 ((E)-3-(3-Chlorophenyl)-N-(4-(1,3-dimethyl-2,6-dioxo-2,3,6,7-tetrahydro-1H-purin-8-yl) phenyl) acrylamide and L32 ((E)-3-(3-Chlorophenyl)-N-(3-(1,3-dimethyl-2,6-dioxo-2,3,6,7-tetrahydro-1H-purin-8-yl)phenyl)acrylamide) had a high affinity (S-score: -10.160 and -7.344 kcal/mol) with the pocket of hMAO-B and hA2AR targets respectively, and the stability of the studied complexes was confirmed during MD simulations. Also, the MEP maps of compounds 24 and 32 were used to identify the nucleophilic and electrophilic attack regions. Moreover, the bioisosteric replacement approach was successfully applied to design two new analogs of each compound with similar biological activities and low energy scores. Furthermore, ADME-T and Drug-likeness results revealed the promising pharmacokinetic properties and oral bioavailability of these compounds. Thus, compounds L24, L32, and their analogs can undergo further analysis and optimization in order to design new lead compounds with higher efficacy toward Parkinson's disease.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40203-023-00139-3.

The Antioxidative Effects of Picein and Its Neuroprotective Potential: A Review of the Literature

Neurodegenerative diseases (NDDs) are the main cause of dementia in the elderly, having no cure to date, as the currently available therapies focus on symptom remission. Most NDDs will progress despite treatment and eventually result in the death of the patient after several years of a burden on both the patient and the caregivers. Therefore, it is necessary to investigate agents that tackle the disease pathogenesis and can efficiently slow down or halt disease progression, with the hope of curing the patients and preventing further burden and mortality. Accordingly, recent research has focused on disease-modifying treatments with neuroregenerative or neuroprotective effects. For this purpose, it is necessary to understand the pathogenesis of NDDs. It has been shown that oxidative stress plays an important role in the damage to the central nervous system and the progression of neurodegenerative disorders. Furthermore, mitochondrial dysfunction and the accumulation of unfolded proteins, including beta-amyloid (Aβ), tau proteins, and α-synuclein, have been suggested. Accordingly, cellular and molecular studies have investigated the efficacy of several natural compounds (herbs and nutritional agents) for their neuroprotective and antioxidative properties. The most popular herbs suggested for the treatment and/or prevention of NDDs include Withania somnifera (ashwagandha), ginseng, curcumin, resveratrol, Baccopa monnieri, and Ginkgo biloba. In some herbs, such as ginseng, preclinical and clinical evidence are available for supporting its effectiveness; however, in some others, only cellular and animal studies are available. In line with the scant literature in terms of the effectiveness of herbal compounds on NDDs, there are also other herbal agents that have been disregarded. Picein is one of the herbal agents that has been investigated in only a few studies. Picein is the active ingredient of several herbs and can be thus extracted from different types of herbs, which makes it more available. It has shown to have anti-inflammatory properties in cellular and plant studies; however, to date, only one study has suggested its neuroprotective properties. Furthermore, some cellular studies have shown no anti-inflammatory effect of picein. Therefore, a review of the available literature is required to summarize the results of studies on picein. To date, no review study seems to have addressed this issue. Thus, in the present study, we gather the available information about the antioxidative and potential neuroprotective properties of picein and its possible effectiveness in treating NDDs. We also summarize the plants from which picein can be extracted in order to guide researchers for future investigations.

IntraBrain Injector (IBI): A Stereotactic-Guided Device for Repeated Delivery of Therapeutic Agents Into the Brain Parenchyma

BACKGROUND

To deliver therapeutics into the brain, it is imperative to overcome the issue of the blood-brain-barrier (BBB). One of the ways to circumvent the BBB is to administer therapeutics directly into the brain parenchyma. To enhance the treatment efficacy for chronic neurodegenerative disorders, repeated administration to the target location is required. However, this increases the number of operations that must be performed. In this study, we developed the IntraBrain Injector (IBI), a new implantable device to repeatedly deliver therapeutics into the brain parenchyma.

METHODS

We designed and fabricated IBI with medical grade materials, and evaluated the efficacy and safety of IBI in 9 beagles. The trajectory of IBI to the hippocampus was simulated prior to surgery and the device was implanted using 3D-printed adaptor and surgical guides. Ferumoxytol-labeled mesenchymal stem cells (MSCs) were injected into the hippocampus via IBI, and magnetic resonance images were taken before and after the administration to analyze the accuracy of repeated injection.

RESULTS

We compared the planned vs. insertion trajectory of IBI to the hippocampus. With a similarity of 0.990 ± 0.001 (mean ± standard deviation), precise targeting of IBI was confirmed by comparing planned vs. insertion trajectories of IBI. Multiple administrations of ferumoxytol-labeled MSCs into the hippocampus using IBI were both feasible and successful (success rate of 76.7%). Safety of initial IBI implantation, repeated administration of therapeutics, and long-term implantation have all been evaluated in this study.

CONCLUSION

Precise and repeated delivery of therapeutics into the brain parenchyma can be done without performing additional surgeries via IBI implantation.

Therapeutic potential of quinazoline derivatives for Alzheimer's disease: A comprehensive review

Quinazolines are considered as a promising class of bioactive heterocyclic compounds with broad properties. Particularly, the quinazoline scaffold has an impressive role in the design and synthesis of new CNS-active drugs. The drug-like properties and pharmacological characteristics of quinazoline could lead to different drugs with various targets. Among CNS disorders, Alzheimer's disease (AD) is a progressive neurodegenerative disorder with memory loss, cognitive decline and language dysfunction. AD is a complex and multifactorial disease therefore, the need for finding multi-target drugs against this devastative disease is urgent. A literature survey revealed that quinazoline derivatives have diverse therapeutic potential for AD as modulators/inhibitors of β-amyloid, tau protein, cholinesterases, monoamine oxidases, and phosphodiesterases as well as other protective effects. Thus, we describe here the most relevant and recent studies about anti-AD agents with quinazoline structure which can further aid the development and discovery of new anti-AD agents.

Night Photostimulation of Clearance of Beta-Amyloid from Mouse Brain: New Strategies in Preventing Alzheimer's Disease

The deposition of amyloid-β (Aβ) in the brain is a risk factor for Alzheimer's disease (AD). Therefore, new strategies for the stimulation of Aβ clearance from the brain can be useful in preventing AD. Transcranial photostimulation (PS) is considered a promising method for AD therapy. In our previous studies, we clearly demonstrated the PS-mediated stimulation of lymphatic clearing functions, including Aβ removal from the brain. There is increasing evidence that sleep plays an important role in Aβ clearance. Here, we tested our hypothesis that PS at night can stimulate Aβ clearance from the brain more effectively than PS during the day. Our results on healthy mice show that Aβ clearance from the brain occurs faster at night than during wakefulness. The PS course at night improves memory and reduces Aβ accumulation in the brain of AD mice more effectively than the PS course during the day. Our results suggest that night PS is a more promising candidate as an effective method in preventing AD than daytime PS. These data are an important informative platform for the development of new noninvasive and nonpharmacological technologies for AD therapy as well as for preventing Aβ accumulation in the brain of people with disorder of Aβ metabolism, sleep deficit, elderly age, and jet lag.

Ameliorative role of rolipram, PDE-4 inhibitor, against sodium arsenite-induced vascular dementia in rats

Arsenic exposure to the population leads to serious health problems like neurotoxicity, nephrotoxicity, and cardiovascular abnormality. In the present study, the work has been commenced to discover the prospect of rolipram a phosphodiestrase-4 (PDE-4) inhibitor against sodium arsenite (SA)-induced vascular endothelial dysfunction (EnDF) leading to dementia in rats. Wistar rats were treated with SA (5 mg/kg body weight/day orally) for 44 days for induction of vascular EnDF and dementia. Learning and memory were evaluated using Morris water maze (MWM) test. Vascular EnDF was evaluated using aortic ring preparation. Various biochemical parameters were also evaluated like brain oxidative stress (viz. reduced glutathione and thiobarbituric acid reactive substances level), serum nitrite/nitrate activity, acetylcholinesterase activity, and inflammatory markers (viz. neutrophil infiltration in brain and myeloperoxidase). SA-treated rats showed poor performance in water maze trials indicating attenuated memory and ability to learn with significant rise (p < 0.05) in brain acetylcholinesterase activity, brain oxidative stress, neutrophil count, and significant decrease (p < 0.05) in serum nitrite/nitrate levels and vascular endothelial functions. Rolipram (PDE-4 inhibitor) treatment (0.03 mg/kg and 0.06 mg/kg body weight, intraperitoneally daily for 14 days) significantly improved memory and learning abilities, and restored various biochemical parameters and EnDF. It is concluded that PDE-4 modulator may be considered the prospective target for the treatment of SA-induced vascular EnDF and related dementia.

Potential Roles of Sestrin2 in Alzheimer's Disease: Antioxidation, Autophagy Promotion, and Beyond

Alzheimer’s disease (AD) is the most common age-related neurodegenerative disease. It presents with progressive memory loss, worsens cognitive functions to the point of disability, and causes heavy socioeconomic burdens to patients, their families, and society as a whole. The underlying pathogenic mechanisms of AD are complex and may involve excitotoxicity, excessive generation of reactive oxygen species (ROS), aberrant cell cycle reentry, impaired mitochondrial function, and DNA damage. Up to now, there is no effective treatment available for AD, and it is therefore urgent to develop an effective therapeutic regimen for this devastating disease. Sestrin2, belonging to the sestrin family, can counteract oxidative stress, reduce activity of the mammalian/mechanistic target of rapamycin (mTOR), and improve cell survival. It may therefore play a crucial role in neurodegenerative diseases like AD. However, only limited studies of sestrin2 and AD have been conducted up to now. In this article, we discuss current experimental evidence to demonstrate the potential roles of sestrin2 in treating neurodegenerative diseases, focusing specifically on AD. Strategies for augmenting sestrin2 expression may strengthen neurons, adapting them to stressful conditions through counteracting oxidative stress, and may also adjust the autophagy process, these two effects together conferring neuronal resistance in cases of AD.

Multiple regulation and targeting effects of borneol in the neurovascular unit in neurodegenerative diseases

Efficient delivery of brain-targeted drugs is highly important for the success of therapies in neurodegenerative diseases. Borneol has several biological activities, such as anti-inflammatory and cell penetration enhancing effect, and can regulate processes in the neurovascular unit (NVU), such as protein toxic stress, autophagosome/lysosomal system, oxidative stress, programmed cell death and neuroinflammation. However, the influence of borneol on NVU in neurodegenerative diseases has not been fully explained. This study searched the keywords 'borneol', 'neurovascular unit', 'endothelial cell', 'astrocyte', 'neuron', 'blood-brain barrier', 'neurodegenerative diseases' and 'brain disease', in PubMed, BioMed Central, China National Knowledge Infrastructure (CNKI), and Bing search engines to explore the influence of borneol on NVU. In addition to the principle and mechanism of penetration of borneol in the brain, this study also showed its multiple regulation effects on NVU. Borneol was able to penetrate the blood-brain barrier (BBB), affecting the signal transmission between BBB and the microenvironment of the brain, down-regulating the expression of inflammatory and oxidative stress proteins in NVU, especially in microglia and astrocytes. In summary, borneol is a potential drug delivery agent for drugs against neurodegenerative diseases.

Therapeutic potential of catalpol and geniposide in Alzheimer's and Parkinson's diseases: A snapshot of their underlying mechanisms

Rehmannia glutinosa, the fresh or dried root of Rehmannia glutinosa (Gaertn.) Libosch. ex Fisch. & Mey., and Gardenia, the fruit of Gardenia jasminoides Ellis from Rubiaceae, both are famous traditional Chinese medicines that have been traditionally used in China. Catalpol and geniposide, as two kinds of iridoid glycosides with high activities, are the main bioactive components in Rehmannia glutinosa and Gardenia jasminoides Ellis, respectively. Over the past few decades, catalpol and geniposide have been widely studied for their therapeutic effects. The preclinical experiments demonstrated that they possessed significant neuroprotective activities against Alzheimer's disease, Parkinson's disease, stroke, and depression, etc. In this paper, the pharmacological effects and mechanisms of catalpol and geniposide on Alzheimer's disease and Parkinson's disease from 2005 to now were systematically summarized and comprehensively analyzed. At the same time, the pharmacokinetic characteristics of the analyzed compounds were also described, hoping to provide some enlightenment for the design, research, and development of iridoid glycosides.

Nutraceutical regulation of miRNAs involved in neurodegenerative diseases and brain cancers

The human brain is a well-connected, intricate network of neurons and supporting glial cells. Neurodegenerative diseases arise as a consequence of extensive loss of neuronal cells leading to disruption of their natural structure and function. On the contrary, rapid proliferation and growth of glial as well as neuronal cells account for the occurrence of malignancy in brain. In both cases, the molecular microenvironment holds pivotal importance in the progression of the disease. MicroRNAs (miRNA) are one of the major components of the molecular microenvironment. miRNAs are small, noncoding RNAs that control gene expression post-transcriptionally. As compared to other tissues, the brain expresses a substantially high number of miRNAs. In the early stage of neurodegeneration, miRNA expression upregulates, while in oncogenesis, miRNA expression is gradually lost. Neurodegeneration and brain cancer is presumed to be under the influence of identical pathways of cell proliferation, differentiation and cell death which are tightly regulated by miRNAs. It has been confirmed experimentally that miRNA expression can be regulated by nutraceuticals - macronutrients, micronutrients or natural products derived from food; thereby making dietary supplements immensely significant for targeting miRNAs having altered expression patterns during neurodegeneration or oncogenesis. In this review, we will discuss in detail, about the common miRNAs involved in brain cancers and neurodegenerative diseases along with the comprehensive list of miRNAs involved separately in both pathological conditions. We will also discuss the role of nutraceuticals in the regulation of those miRNAs which are involved in both of these pathological conditions.

Apelin-13 protects human neuroblastoma SH-SY5Y cells against amyloid-beta induced neurotoxicity: Involvement of anti oxidant and anti apoptotic properties

OBJECTIVES

We investigated the effect of apelin-13 on the cellular model of AD, amyloid-β (Aβ) treated SH-SY5Y cells in rats.

METHODS

The SH-SY5Y cells were pretreated with different doses of apelin-13 (1, 2.5, 5, and 10 μg/mL), half an hour before adding 50% Aβ treatment. After 24 h, cells were evaluated for survival, oxidative stress, mitochondrial calcium release, caspase-3, and cytochrome c levels, compared to control group (beta-actin). Statistical analysis was performed by SPSS 16.

RESULTS

Apelin-13 at the dose of 2.5 μg/mL protected against IC50 Aβ (p<0.001). Apelin-13 at doses of 1, 2.5, and 5 μg/mL showed protective effects against the reactive oxygen species (ROS) produced by Aβ (p<0.001). Apelin-13 at doses of 2.5 and 5 μg/mL reduced calcium release, caspase-3, and cytochrome c (all p<0.001).

CONCLUSIONS

Apelin-13 prevented apoptosis, oxidative stress, and mitochondrial toxicity and can be a suitable option for treatment of AD. The appropriate treatment strategy for humans has to be investigated in future studies.

Plant-Derived Natural Compounds for the treatment of Amyotrophic Lateral Sclerosis: An Update

Background

Amyotrophic lateral sclerosis (ALS) is a motor neuron disease (MND) that typically causes death within 3-5 years after diagnosis. Regardless of the substantial scientific knowledge accrued more than a century ago, truly effective therapeutic strategies remain distant. Various conventional drugs are being used but are having several adverse effects.

Objective/Aim

The current study aims to thoroughly review plant-derived compounds with well-defined ALS activities and their structure-activity relationships. Moreover, the review also focuses on complex genetics, clinical trials, and the use of natural products that might decrypt the future and novel therapeutics in ALS.

Methods

The collection of data for the compilation of this review work was searched in PubMed Scopus, Google Scholar, and Science Direct.

Results

Results showed that phytochemicals like-Ginkgolides, Protopanaxatriol, Genistein, epigallocatechingallate, resveratrol, cassoside, and others possess Amyotrophic lateral sclerosis (ALS) activity by various mechanisms.

Conclusion

These plant-derived compounds may be considered as supplements for conventional (ALS). Moreover, further preclinical and clinical studies are required to understand the structure-activity relationships, metabolism, absorption, and mechanisms of plant-derived natural agents.

Nicotinamide Ameliorates Amyloid Beta-Induced Oxidative Stress-Mediated Neuroinflammation and Neurodegeneration in Adult Mouse Brain

Alzheimer’s disease (AD) is the most predominant age-related neurodegenerative disease, pathologically characterized by the accumulation of aggregates of amyloid beta Aβ_1–42 and tau hyperphosphorylation in the brain. It is considered to be the primary cause of cognitive dysfunction. The aggregation of Aβ_1–42 leads to neuronal inflammation and apoptosis. Since vitamins are basic dietary nutrients that organisms need for their growth, survival, and other metabolic functions, in this study, the underlying neuroprotective mechanism of nicotinamide (NAM) Vitamin B3 against Aβ_1–42 -induced neurotoxicity was investigated in mouse brains. Intracerebroventricular (i.c.v.) Aβ_1–42 injection elicited neuronal dysfunctions that led to memory impairment and neurodegeneration in mouse brains. After 24 h after Aβ_1–42 injection, the mice were treated with NAM (250 mg/kg intraperitoneally) for 1 week. For biochemical and Western blot studies, the mice were directly sacrificed, while for confocal and “immunohistochemical staining”, mice were perfused transcardially with 4% paraformaldehyde. Our biochemical, immunofluorescence, and immunohistochemical results showed that NAM can ameliorate neuronal inflammation and apoptosis by reducing oxidative stress through lowering malondialdehyde and 2,7-dichlorofluorescein levels in an Aβ_1–42-injected mouse brains, where the regulation of p-JNK further regulated inflammatory marker proteins (TNF-α, IL-1β, transcription factor NF-kB) and apoptotic marker proteins (Bax, caspase 3, PARP1). Furthermore, NAM + Aβ treatment for 1 week increased the amount of survival neurons and reduced neuronal cell death in Nissl staining. We also analyzed memory dysfunction via behavioral studies and the analysis showed that NAM could prevent Aβ_1–42 -induced memory deficits. Collectively, the results of this study suggest that NAM may be a potential preventive and therapeutic candidate for Aβ_1–42 -induced reactive oxygen species (ROS)-mediated neuroinflammation, neurodegeneration, and neurotoxicity in an adult mouse model.

Physical exercise improves quality of life, depressive symptoms, and cognition across chronic brain disorders: a transdiagnostic systematic review and meta-analysis of randomized controlled trials

We performed a meta-analysis to synthesize evidence on the efficacy and safety of physical exercise as an add-on therapeutic intervention for quality of life (QoL), depressive symptoms and cognition across six chronic brain disorders: Alzheimer's disease, Huntington's disease, multiple sclerosis, Parkinson's disease, schizophrenia and unipolar depression. 122 studies ( = k) (n = 7231) were included. Exercise was superior to treatment as usual in improving QoL (k = 64, n = 4334, ES = 0.40, p < 0.0001), depressive symptoms (k = 60, n = 2909, ES = 0.78, p < 0.0001), the cognitive domains attention and working memory (k = 21, n = 1313, ES = 0.24, p < 0.009), executive functioning (k = 14, n = 977, ES = 0.15, p = 0.013), memory (k = 12, n = 994, ES = 0.12, p = 0.038) and psychomotor speed (k = 16, n = 896, ES = 0.23, p = 0.003). Meta-regression showed a dose-response effect for exercise time (min/week) on depressive symptoms (β = 0.007, p = 0.012). 69% of the studies that reported on safety, found no complications. Exercise is an efficacious and safe add-on therapeutic intervention showing a medium-sized effect on QoL and a large effect on mood in patients with chronic brain disorders, with a positive dose-response correlation. Exercise also improved several cognitive domains with small but significant effects.

Glaucoma and neuroinflammation: An overview

Glaucoma is an optic neuropathy characterized by well-defined optic disc morphological changes (i.e., cup enlargement, neuroretinal border thinning, and notching, papillary vessel modifications) consequent to retinal ganglion cell loss, axonal degeneration, and lamina cribrosa remodeling. These modifications tend to be progressive and are the main cause of functional damage in glaucoma. Despite the latest findings about the pathophysiology of the disease, the exact trigger mechanisms and the mechanism of degeneration of retinal ganglion cells and their axons have not been completely elucidated. Neuroinflammation may play a role in both the development and the progression of the disease as a result of its effects on retinal environment and retinal ganglion cells. We summarize the latest findings about neuroinflammation in glaucoma and examine the connection between risk factors, neuroinflammation, and retinal ganglion cell degeneration.

Transcranial Photobiomodulation of Clearance of Beta-Amyloid from the Mouse Brain: Effects on the Meningeal Lymphatic Drainage and Blood Oxygen Saturation of the Brain

Here, we demonstrate the therapeutic effects of transcranial photobiomodulation (tPBM, 1267 nm, 32 J/cm2, a 9-day course) in mice with the injected model of Alzheimer's disease (AD) associated with accumulation of beta-amyloid (Aβ) in the brain resulting in neurocognitive deficit vs. the control group (CG) (the neurological severity score (NNS), AD 3.67 ± 0.58 vs. CG 1.00 ± 0.26%, p < 0.05) and mild cerebral hypoxia (AD 72 ± 6% vs. CG 97 ± 2%, p < 0.001). The course of tPBM improved neurocognitive status of mice with AD (NNS, AD 2.03 ± 0.14 vs. CG 1.00 ± 0.26, vs. 2.03 ± 0.14, p < 0.05) due to stimulation of clearance of Aβ from the brain via the meningeal lymphatic vessels (the immunohistochemical and confocal data) and an increase in blood oxygen saturation of the brain tissues (the pulse oximetry data) till 85 ± 2%, p < 0.05. These results open breakthrough strategies for non-pharmacological therapy of AD and clearly demonstrate that tPBM might be a promising therapeutic target for preventing or delaying AD based on stimulation of oxygenation of the brain tissues and activation of clearance of toxic molecules via the cerebral lymphatics.

Brain-Targeted Delivery of Pre-miR-29b Using Lactoferrin-Stearic Acid-Modified-Chitosan/Polyethyleneimine Polyplexes

The efficacy of brain therapeutics is largely hampered by the presence of the blood–brain barrier (BBB), mainly due to the failure of most (bio) pharmaceuticals to cross it. Accordingly, this study aims to develop nanocarriers for targeted delivery of recombinant precursor microRNA (pre-miR-29b), foreseeing a decrease in the expression of the BACE1 protein, with potential implications in Alzheimer’s disease (AD) treatment. Stearic acid (SA) and lactoferrin (Lf) were successfully exploited as brain-targeting ligands to modify cationic polymers (chitosan (CS) or polyethyleneimine (PEI)), and its BBB penetration behavior was evaluated. The intracellular uptake of the dual-targeting drug delivery systems by neuronal cell models, as well as the gene silencing efficiency of recombinant pre-miR-29b, was analyzed in vitro. Labeled pre-miR-29b-CS/PEI-SA-Lf systems showed very strong fluorescence in the cytoplasm and nucleus of RBE4 cells, being verified the delivery of pre-miR-29b to neuronal cells after 1 h transfection. The experiment of transport across the BBB showed that CS-SA-Lf delivered 65% of recombinant pre-miR-29b in a period of 4 h, a significantly higher transport ratio than the 42% found for PEI-SA-Lf in the same time frame. Overall, a novel procedure for the dual targeting of DDS is disclosed, opening new perspectives in nanomedicines delivery, whereby a novel drug delivery system harvests the merits and properties of the different immobilized ligands.

Dexmedetomidine improves early postoperative neurocognitive disorder in elderly male patients undergoing thoracoscopic lobectomy

Perioperative neurocognitive disorder (PND) is a common complication following thoracic surgery that frequently occurs in patients ≥65 years. PND includes postoperative cognitive dysfunction (POCD) and postoperative delirium (POD). To investigate whether intravenous dexmedetomidine (DEX) is able to improve neurocognitive function in elderly male patients following thoracoscopic lobectomy, a randomized, double-blinded, placebo-controlled trial was performed at the Affiliated Hospital of Inner Mongolia Medical University (Hohhot, China). Patients aged ≥65 years were enrolled and were subjected to thoracic surgery under general anesthesia. A computer-generated randomization sequence was used to randomly assign patients (at a 1:1 ratio) to receive either intravenous DEX (0.5 µg/kg per h, from induction until chest closure) or placebo (intravenous normal saline). The primary endpoint was the result of the Mini-Mental State Examination (MMSE). The secondary endpoints were the results of the Montreal Cognitive Assessment (MoCA) and those obtained with the Confusion Assessment Method (CAM), as well as the incidence of POCD and POD during the first 7 postoperative days. Other observational indexes included sleep quality at night, self-anxiety scale prior to the operation and 7 days following the operation and the visual analogue scale (VAS) score at rest and during movement on the first and third day following the operation. Furthermore, at 6 h following surgery, the MMSE score in the DEX group was significantly higher than that in the saline group. At 6 h and on the first day postoperatively, the MoCA score in the DEX group was significantly higher than that in the saline group. The incidence of POCD and POD in the DEX group was 13.2 and 7.5%, respectively, while that in the saline group was 35.8 and 11.3%, respectively. There was a significant difference in the incidence of POCD between the two groups (P<0.01). In the DEX group, mean sleep quality was increased, whereas the mean VAS was decreased compared with the corresponding values in the saline group. In conclusion, elderly male patients who underwent thoracoscopic lobectomy under continuous infusion of DEX (0.5 µg/kg/h) exhibited a reduced incidence of POCD during the first 7 postoperative days as compared with the placebo group. Furthermore, DEX improved the subjective sleep quality in the first postoperative night, reduced anxiety and alleviated postoperative pain. In addition, it increased the incidence of bradycardia. The present study was registered in the Chinese Clinical Trial Registry (www.chictr.org.cn; registration no. ChiCTR-IPR-17010958).

Anti-inflammatory and Neuroprotective Agents in Clinical Trials for CNS Disease and Injury: Where Do We Go From Here?

Neurological disorders are major contributors to death and disability worldwide. The pathology of injuries and disease processes includes a cascade of events that often involve molecular and cellular components of the immune system and their interaction with cells and structures within the central nervous system. Because of this, there has been great interest in developing neuroprotective therapeutic approaches that target neuroinflammatory pathways. Several neuroprotective anti-inflammatory agents have been investigated in clinical trials for a variety of neurological diseases and injuries, but to date the results from the great majority of these trials has been disappointing. There nevertheless remains great interest in the development of neuroprotective strategies in this arena. With this in mind, the complement system is being increasingly discussed as an attractive therapeutic target for treating brain injury and neurodegenerative conditions, due to emerging data supporting a pivotal role for complement in promoting multiple downstream activities that promote neuroinflammation and degeneration. As we move forward in testing additional neuroprotective and immune-modulating agents, we believe it will be useful to review past trials and discuss potential factors that may have contributed to failure, which will assist with future agent selection and trial design, including for complement inhibitors. In this context, we also discuss inhibition of the complement system as a potential neuroprotective strategy for neuropathologies of the central nervous system.

Sleep as a Novel Biomarker and a Promising Therapeutic Target for Cerebral Small Vessel Disease: A Review Focusing on Alzheimer's Disease and the Blood-Brain Barrier

Cerebral small vessel disease (CSVD) is a leading cause of cognitive decline in elderly people and development of Alzheimer’s disease (AD). Blood–brain barrier (BBB) leakage is a key pathophysiological mechanism of amyloidal CSVD. Sleep plays a crucial role in keeping health of the central nervous system and in resistance to CSVD. The deficit of sleep contributes to accumulation of metabolites and toxins such as beta-amyloid in the brain and can lead to BBB disruption. Currently, sleep is considered as an important informative platform for diagnosis and therapy of AD. However, there are no effective methods for extracting of diagnostic information from sleep characteristics. In this review, we show strong evidence that slow wave activity (SWA) (0–0.5 Hz) during deep sleep reflects glymphatic pathology, the BBB leakage and memory deficit in AD. We also discuss that diagnostic and therapeutic targeting of SWA in AD might lead to be a novel era in effective therapy of AD. Moreover, we demonstrate that SWA can be pioneering non-invasive and bed–side technology for express diagnosis of the BBB permeability. Finally, we review the novel data about the methods of detection and enhancement of SWA that can be biomarker and a promising therapy of amyloidal CSVD and CSVD associated with the BBB disorders.

An activity prediction model for steroidal and triterpenoidal inhibitors of Acetylcholinesterase enzyme

Nowadays, the importance of computational methods in the design of therapeutic agents in a more efficient way is indisputable. Particularly, these methods have been important in the design of novel acetylcholinesterase enzyme inhibitors related to Alzheimer's disease. In this sense, in this report a computational model of linear prediction of acetylcholinesterase inhibitory activity of steroids and triterpenes is presented. The model is based in a correlation between binding energies obtained from molecular dynamic simulations (after docking studies) and [Formula: see text] values of a training set. This set includes a family of natural and semi-synthetic structurally related alkaloids reported in bibliography. These types of compounds, with some structural complexity, could be used as building blocks for the synthesis of many important biologically active compounds Therefore, the present study proposes an alternative based on the use of conventional and easily accessible tools to make progress on the rational design of molecules with biological activity.

Photobiomodulation of lymphatic drainage and clearance: perspective strategy for augmentation of meningeal lymphatic functions

There is a hypothesis that augmentation of the drainage and clearing function of the meningeal lymphatic vessels (MLVs) might be a promising therapeutic target for preventing neurological diseases. Here we investigate mechanisms of photobiomodulation (PBM, 1267 nm) of lymphatic drainage and clearance. Our results obtained at optical coherence tomography (OCT) give strong evidence that low PBM doses (5 and 10 J/cm²) stimulate drainage function of the lymphatic vessels via vasodilation (OCT data on the mesenteric lymphatics) and stimulation of lymphatic clearance (OCT data on clearance of gold nanorods from the brain) that was supported by confocal imaging of clearance of FITC-dextran from the cortex via MLVs. We assume that PBM-mediated relaxation of the lymphatic vessels can be possible mechanisms underlying increasing the permeability of the lymphatic endothelium that allows molecules transported by the lymphatic vessels and explain PBM stimulation of lymphatic drainage and clearance. These findings open new strategies for the stimulation of MLVs functions and non-pharmacological therapy of brain diseases.

Association of Neuropathological Markers in the Parietal Cortex With Antemortem Cognitive Function in Persons With Mild Cognitive Impairment and Alzheimer Disease

The associations between cognitive function and neuropathological markers in patients with mild cognitive impairment (MCI) and Alzheimer disease (AD) remain only partly defined. We investigated relationships between antemortem global cognitive scores and β-amyloid (Aβ), tau, TDP-43, synaptic proteins and other key AD neuropathological markers assessed by biochemical approaches in postmortem anterior parietal cortex samples from 36 subjects (12 MCI, 12 AD and 12 not cognitively impaired) from the Religious Orders Study. Overall, the strongest negative correlation coefficients associated with global cognitive scores were obtained for insoluble phosphorylated tau (r2 = -0.484), insoluble Aβ42 (r2 = -0.389) and neurofibrillary tangle counts (r2 = -0.494) (all p < 0.001). Robust inverse associations with cognition scores were also established for TDP-43-positive cytoplasmic inclusions (r2 = -0.476), total insoluble tau (r2 = -0.385) and Aβ plaque counts (r2 = -0.426). Sarkosyl (SK)- or formic acid (FA)-extracted tau showed similar interrelations. On the other hand, synaptophysin (r2 = +0.335), pS403/404 TDP-43 (r2 = +0.265) and septin-3 (r2 = +0.257) proteins positively correlated with cognitive scores. This study suggests that tau and Aβ42 in their insoluble aggregated forms, synaptic proteins and TDP-43 are the markers in the parietal cortex that are most strongly associated with cognitive function. This further substantiates the relevance of investigating these markers to understand the pathogenesis of AD and develop therapeutic tools.

Intracellular Targeting of Heat Shock Proteins in Differentiated Human Neuronal Cells Following Proteotoxic Stress

HSPA6 (Hsp70B') is an inducible member of the Hsp70 (HSPA) family of heat shock proteins that is present in the human genome and not found in mouse and rat. Hence it is lacking in current animal models of neurodegenerative diseases. To advance knowledge of the little studied HSPA6, differentiated human neuronal SH-SY5Y cells were treated with the proteotoxic stress-inducing agent MG132. A robust induction of HSPA6 was apparent which localized to the periphery of MG132-induced protein aggregates in the neuronal cytoplasm. Components of the protein disaggregation/refolding machine that co-operate with Hsp70 also targeted the periphery of cytoplasmic protein aggregates, including DNAJB1 (Hsp40-1), HSPH1 (Hsp105α), and HSPB1 (Hsp27). These data suggest that HSPA6 is involved in the response of human neuronal cells to proteotoxic stress that is a feature of neurodegenerative diseases which have been characterized as protein misfolding disorders. Constitutively expressed HSPA8 (Hsc70) also localized tothe periphery of cytoplasmic protein aggregates following the treatment of differentiated human neuronal cells with MG132. HSPA8 could provide a rapid response to proteotoxic stress in neuronal cells, circumventing the time required to upregulate inducible Hsps.

Purinergic Signalling in Parkinson's Disease: A Multi-target System to Combat Neurodegeneration

Parkinson's disease (PD) is the second most common neurodegenerative disorder, characterized by progressive loss of dopaminergic neurons that results in characteristic motor and non-motor symptoms. L-3,4 dihydroxyphenylalanine (L-DOPA) is the gold standard therapy for the treatment of PD. However, long-term use of L-DOPA leads to side effects such as dyskinesias and motor fluctuation. Since purines have neurotransmitter and co-transmitter properties, the function of the purinergic system has been thoroughly studied in the nervous system. Adenosine and adenosine 5'-triphosphate (ATP) are modulators of dopaminergic neurotransmission, neuroinflammatory processes, oxidative stress, excitotoxicity and cell death via purinergic receptor subtypes. Aberrant purinergic receptor signalling can be either the cause or the result of numerous pathological conditions, including neurodegenerative disorders. Many data confirm the involvement of purinergic signalling pathways in PD. Modulation of purinergic receptor subtypes, the activity of ectonucleotidases and ATP transporters could be beneficial in the treatment of PD. We give a brief summary of the background of purinergic signalling focusing on its roles in PD. Possible targets for pharmacological treatment are highlighted.

Pilot study of transcranial photobiomodulation of lymphatic clearance of beta-amyloid from the mouse brain: breakthrough strategies for non-pharmacologic therapy of Alzheimer's disease

In this pilot study, we analyzed effects of transcranial photobiomodulation (tPBM, 1267 nm, 32 J/cm²) on clearance of beta-amyloid (Aβ) from the mouse brain. The immunohistochemical and confocal data clearly demonstrate the significant reduction of deposition of Aβ plaques in mice after tPBM vs. untreated animals. The behavior tests showed that tPBM improved the cognitive, memory and neurological status of mice with Alzheimer's disease (AD). Using of our original method based on optical coherence tomography (OCT) analysis of clearance of gold nanorods (GNRs) from the brain, we proposed possible mechanism underlying tPBM-stimulating effects on clearance of Aβ via the lymphatic system of the brain and the neck. These results open breakthrough strategies for a non-pharmacological therapy of Alzheimer's disease and clearly demonstrate that tPBM might be a promising therapeutic target for preventing or delaying Alzheimer's disease.

Suppressing nNOS Enzyme by Small-Interfering RNAs Protects SH-SY5Y Cells and Nigral Dopaminergic Neurons from 6-OHDA Injury

Nitric oxide (NO) has chemical properties that make it uniquely suitable as an intracellular and intercellular messenger. NO is produced by the activity of the enzyme nitric oxide synthases (NOS). There is substantial and mounting evidence that slight abnormalities of NO may underlie a wide range of neurodegenerative disorders. NO participates of the oxidative stress and inflammatory processes that contribute to the progressive dopaminergic loss in Parkinson's disease (PD). The present study aimed to evaluate in vitro and in vivo the effects of neuronal NOS-targeted siRNAs on the injury caused in dopaminergic neurons by the toxin 6-hidroxydopamine (6-OHDA). First, we confirmed (immunohistochemistry and Western blotting) that SH-SY5Y cell lineage expresses the dopaminergic marker tyrosine hydroxylase (TH) and the protein under analysis, neuronal NOS (nNOS). We designed four siRNAs by using the BIOPREDsi algorithm choosing the one providing the highest knockdown of nNOS mRNA in SH-SY5Y cells, as determined by qPCR. siRNA 4400 carried by liposomes was internalized into cells, caused a concentration-dependent knockdown on nNOS, and reduced the toxicity induced by 6-OHDA (p < 0.05). Regarding in vivo action in the dopamine-depleted animals, intra-striatal injection of siRNA 4400 at 4 days prior 6-OHDA produced a decrease in the rotational behavior induced by apomorphine. Finally, siRNA 4400 mitigated the loss of TH(+) cells in substantia nigra dorsal and ventral part. In conclusion, the suppression of nNOS enzyme by targeted siRNAs modified the progressive death of dopaminergic cells induced by 6-OHDA and merits further pre-clinical investigations as a neuroprotective approach for PD.

Subnanomolar indazole-5-carboxamide inhibitors of monoamine oxidase B (MAO-B) continued: indications of iron binding, experimental evidence for optimised solubility and brain penetration

Pharmacological and physicochemical studies of N-unsubstituted indazole-5-carboxamides (subclass I) and their structurally optimised N1-methylated analogues (subclass II), initially developed as drug and radioligand candidates for the treatment and diagnosis of Parkinson’s disease (PD), are presented. The compounds are highly brain permeable, selective, reversible, and competitive monoamine oxidase B (MAO-B) inhibitors with improved water-solubility and subnanomolar potency (pIC₅₀ >8.8). Using a well-validated, combined X-ray/modelling technology platform, we performed a semi-quantitative analysis of the binding modes of all compounds and investigated the role of the indazole N1 position for their MAO-B inhibitory activity. Moreover, compounds NTZ-1006, 1032, and 1441 were investigated for their ability to bind Fe²⁺ and Fe³⁺ ions using UV-visible spectroscopy.

Disease modification and Neuroprotection in neurodegenerative disorders

Background

Disease modifying therapies (DMTs) are urgently needed for neurodegenerative diseases (NDD) such as Alzheimer’s disease (AD) and many other disorders characterized by protein aggregation and neurodegeneration. Despite advances in understanding the neurobiology of NDD, there are no approved DMTs.

Discussion

Defining disease-modification is critical to drug-development programs. A DMT is an intervention that produces an enduring change in the trajectory of clinical decline of an NDD by impacting the disease processes leading to nerve cell death. A DMT is neuroprotective, and neuroprotection will result in disease modification. Disease modification can be demonstrated in clinical trials by a drug-placebo difference in clinical outcomes supported by a drug-placebo difference on biomarkers reflective of the fundamental pathophysiology of the NDD. Alternatively, disease modification can be supported by findings on a staggered start or delayed withdrawal clinical trial design. Collecting multiple biomarkers is necessary to support a comprehensive view of disease modification.

Conclusion

Disease modification is established by demonstrating an enduring change in the clinical trajectory of an NDD based on intervention in the fundamental pathophysiology of the disease leading to nerve cell death. Supporting data are collected in clinical trials. Effectively defining a DMT will assist in NDD drug development programs.

Old and new challenges in Parkinson's disease therapeutics

Parkinson's disease (PD) is a neurodegenerative disorder characterized by the degeneration of dopaminergic neurons and/or loss od neuronal projections, in several dopaminergic networks. Current treatments for idiopathic PD rely mainly on the use of pharmacologic agents to improve motor symptomatology of PD patients. Nevertheless, so far PD remains an incurable disease. Therefore, it is of utmost importance to establish new therapeutic strategies for PD treatment. Over the last 20 years, several molecular, gene and cell/stem-cell therapeutic approaches have been developed with the aim of counteracting or retarding PD progression. The scope of this review is to provide an overview of PD related therapies and major breakthroughs achieved within this field. In order to do so, this review will start by focusing on PD characterization and current treatment options covering thereafter molecular, gene and cell/stem cell-based therapies that are currently being studied in animal models of PD or have recently been tested in clinical trials. Among stem cell-based therapies, those using MSCs as possible disease modifying agents for PD therapy and, specifically, the MSCs secretome contribution to meet the clinical challenge of counteracting or retarding PD progression, will be more deeply explored.

Defining Disease Modifying Therapy for Alzheimer's Disease

BACKGROUND

Disease-modifying therapies (DMTs) are urgently needed to treat the growing number of individuals with Alzheimer's disease (AD) or at immanent risk for AD. A definition of DMT is required to facilitate the process of DMT drug development.

PROCESS

This is a review of the state of the science with regard to definition and development of DMTs.

RESULTS

A DMT is as an intervention that produces an enduring change in the clinical progression of AD by interfering in the underlying pathophysiological mechanisms of the disease process that lead to cell death. Demonstration of DMT efficacy is garnered through clinical trial designs and biomarkers. Evidence of disease modification in the drug development process is based on trial designs such as staggered start and delayed withdrawal showing an enduring effect on disease course or on combined clinical outcomes and correlated biomarker evidence of an effect on the underlying pathophysiological processes of the disease. Analytic approaches such as showing change in slope of cognitive decline, increasing drug-placebo difference over time, and delay of disease milestones are not conclusive by themselves but support the presence of a disease modifying effect. Neuroprotection is a related concept whose demonstration depends on substantiating disease modification. No single type of evidence in itself is sufficient to prove disease modification - consistency, robustness, and variety of sources of data will all contribute to convincing stakeholders that an agent is a DMT.

CONCLUSION

DMT is defined by its enduring effect on processes leading to cell death. A variety of types of data can be used to support the hypothesis that disease modification has occurred.

Differential Targeting of Hsp70 Heat Shock Proteins HSPA6 and HSPA1A with Components of a Protein Disaggregation/Refolding Machine in Differentiated Human Neuronal Cells following Thermal Stress

Heat shock proteins (Hsps) co-operate in multi-protein machines that counter protein misfolding and aggregation and involve DNAJ (Hsp40), HSPA (Hsp70), and HSPH (Hsp105α). The HSPA family is a multigene family composed of inducible and constitutively expressed members. Inducible HSPA6 (Hsp70B') is found in the human genome but not in the genomes of mouse and rat. To advance knowledge of this little studied HSPA member, the targeting of HSPA6 to stress-sensitive neuronal sites with components of a disaggregation/refolding machine was investigated following thermal stress. HSPA6 targeted the periphery of nuclear speckles (perispeckles) that have been characterized as sites of transcription. However, HSPA6 did not co-localize at perispeckles with DNAJB1 (Hsp40-1) or HSPH1 (Hsp105α). At 3 h after heat shock, HSPA6 co-localized with these members of the disaggregation/refolding machine at the granular component (GC) of the nucleolus. Inducible HSPA1A (Hsp70-1) and constitutively expressed HSPA8 (Hsc70) co-localized at nuclear speckles with components of the machine immediately after heat shock, and at the GC layer of the nucleolus at 1 h with DNAJA1 and BAG-1. These results suggest that HSPA6 exhibits targeting features that are not apparent for HSPA1A and HSPA8.

Nutraceuticals against Neurodegeneration: A Mechanistic Insight

The mechanisms underlying neurodegenerative disorders are complex and multifactorial; however, accumulating evidences suggest few common shared pathways. These common pathways include mitochondrial dysfunction, intracellular Ca²⁺ overload, oxidative stress and inflammation. Often multiple pathways co-exist, and therefore limit the benefits of therapeutic interventions. Nutraceuticals have recently gained importance owing to their multifaceted effects. These food-based approaches are believed to target multiple pathways in a slow but more physiological manner without causing severe adverse effects. Available information strongly supports the notion that apart from preventing the onset of neuronal damage, nutraceuticals can potentially attenuate the continued progression of neuronal destruction. In this article, we i) review the common pathways involved in the pathogenesis of the toxicants-induced neurotoxicity and neurodegenerative disorders with special emphasis on Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD), Multiple sclerosis (MS) and Amyotrophic lateral sclerosis (ALS), and ii) summarize current research advancements on the effects of nutraceuticals against these detrimental pathways.

Current Therapy of Drugs in Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS), commonly termed as motor neuron disease (MND) in UK, is a chronically lethal disorder among the neurodegenerative diseases, meanwhile. ALS is basically irreversible and progressive deterioration of upper and lower motor neurons in the motor cortex, brain stem and medulla spinalis. Riluzole, used for the treatment of ALS, was demonstrated to slightly delay the initiation of respiratory dysfunction and extend the median survival of patients by a few months. In this study, the key biochemical defects were discussed, such as: mutant Cu/Zn superoxide dismutase, mitochondrial protectants, and anti-excitotoxic/ anti-oxidative / anti-inflammatory/ anti-apoptotic agents, so the related drug candidates that have been studied in ALS models would possibly be further used in ALS patients.

Neuroprotection for glaucoma: Requirements for clinical translation

Within the field of glaucoma research, neuroprotection is defined as slowing the functional loss in glaucoma by a mechanism independent of lowering of intraocular pressure. There is currently a great potential for research surrounding neuroprotection as it relates to glaucoma. Anatomical targets for neuroprotection should focus on upstream rather than downstream factors, and could include any part of the retinal ganglion cell, the glia, especially astrocytes or Muller cells, and vasculature. The great number of anatomical targets is exceeded only by the number of possible biochemical pathways and potential treatments. Successful treatment may be accomplished through the targeting of one or even a combination of multiple pathways. Once a treatment is shown effective in vitro, it should be evaluated in vivo with carefully chosen animal models and studied in sufficient numbers to detect statistically and clinically significant effects. Such a drug should have few systemic side effects and its delivery should be optimized so as to encourage compliance. There are still a multitude of possible screens available to test the efficacy of a neuroprotective drug and a single gold standard is ideal for the accurate assessment and comparison of new drugs. Future studies in neuroprotection should investigate the genetic component of the disease, novel pharmaceutical agents for new or known pathways, modulations of scleral biomechanics, and relation to research of other complex disorders of the central nervous system.

Dynamics of the association of heat shock protein HSPA6 (Hsp70B') and HSPA1A (Hsp70-1) with stress-sensitive cytoplasmic and nuclear structures in differentiated human neuronal cells

Heat shock proteins (Hsps) are cellular repair agents that counter the effects of protein misfolding that is a characteristic feature of neurodegenerative diseases. HSPA1A (Hsp70-1) is a widely studied member of the HSPA (Hsp70) family. The little-studied HSPA6 (Hsp70B') is present in the human genome and absent in mouse and rat; hence, it is missing in current animal models of neurodegenerative diseases. Differentiated human neuronal SH-SY5Y cells were employed to compare the dynamics of the association of YFP-tagged HSPA6 and HSPA1A with stress-sensitive cytoplasmic and nuclear structures. Following thermal stress, live-imaging confocal microscopy and Fluorescence Recovery After Photobleaching (FRAP) demonstrated that HSPA6 displayed a prolonged and more dynamic association, compared to HSPA1A, with centrioles that play critical roles in neuronal polarity and migration. HSPA6 and HSPA1A also targeted nuclear speckles, rich in RNA splicing factors, and the granular component of the nucleolus that is involved in rRNA processing and ribosomal subunit assembly. HSPA6 and HSPA1A displayed similar FRAP kinetics in their interaction with nuclear speckles and the nucleolus. Subsequently, during the recovery from neuronal stress, HSPA6, but not HSPA1A, localized with the periphery of nuclear speckles (perispeckles) that have been characterized as transcription sites. The stress-induced association of HSPA6 with perispeckles displayed the greatest dynamism compared to the interaction of HSPA6 or HSPA1A with other stress-sensitive cytoplasmic and nuclear structures. This suggests involvement of HSPA6 in transcriptional recovery of human neurons from cellular stress that is not apparent for HSPA1A.

Targeting of Heat Shock Protein HSPA6 (HSP70B') to the Periphery of Nuclear Speckles is Disrupted by a Transcription Inhibitor Following Thermal Stress in Human Neuronal Cells

Heat shock proteins (Hsps) are a set of highly conserved proteins involved in cellular repair and protective mechanisms. The intracellular localization of inducible members of the HSPA (HSP70) family can be used as an index to identify stress-sensitive sites in differentiated human neuronal cells. Following thermal stress, the little studied HSPA6 (HSP70B') was targeted to the periphery of nuclear speckles (perispeckles) that are sites of transcription factories. Triptolide, a fast-acting transcription inhibitor, knocked down levels of the large subunit of RNA polymerase II, RPB1, during the time-frame when HSPA6 associated with perispeckles. Administration of triptolide to heat shocked human neuronal SH-SY5Y cells, disrupted HSPA6 localization to perispeckles, suggesting the involvement of HSPA6 in transcriptional recovery after stress. The HSPA6 gene is present in the human genome but is not found in the genomes of the mouse and rat. Hence current animal models of neurodegenerative diseases lack a member of the HSPA family that exhibits the feature of stress-induced targeting to perispeckles.

Induction of heat shock proteins in differentiated human neuronal cells following co-application of celastrol and arimoclomol

Few effective therapies exist for the treatment of neurodegenerative diseases that have been characterized as protein misfolding disorders. Upregulation of heat shock proteins (Hsps) mitigates against the accumulation of misfolded, aggregation-prone proteins and synaptic dysfunction, which is recognized as an early event in neurodegenerative diseases. Enhanced induction of a set of Hsps in differentiated human SH-SY5Y neuronal cells was observed following co-application of celastrol and arimoclomol, compared to their individual application. The dosages employed did not affect cell viability or neuronal process morphology. The induced Hsps included the little studied HSPA6 (Hsp70B'), a potentially neuroprotective protein that is present in the human genome but not in rat and mouse and hence is missing in current animal models of neurodegenerative disease. Enhanced induction of HSPA1A (Hsp70-1), DNAJB1 (Hsp40), HO-1 (Hsp32), and HSPB1 (Hsp27) was also observed. Celastrol activates heat shock transcription factor 1 (HSF1), the master regulator of Hsp gene transcription, and also exhibits potent anti-inflammatory and anti-oxidant activities. Arimoclomol is a co-activator that prolongs the binding of activated HSF1 to heat shock elements (HSEs) in the promoter regions of inducible Hsp genes. Elevated Hsp levels peaked at 10 to 12 h for HSPA6, HSPA1A, DNAJB1, and HO-1 and at 24 h for HSPB1. Co-application of celastrol and arimoclomol induced higher Hsp levels compared to heat shock paired with arimoclomol. The co-application strategy of celastrol and arimoclomol targets multiple neurodegenerative disease-associated pathologies including protein misfolding and protein aggregation, inflammatory and oxidative stress, and synaptic dysfunction.

Pridopidine for the treatment of Huntington's disease

INTRODUCTION

Huntington's disease is a rare dominantly-inherited neurodegenerative disease with motor, cognitive and behavioral manifestations. It results from an expanded unstable trinucleotide repeat in the coding region of the huntingtin gene. Treatment is symptomatic, but a poor evidence baseguides selection of therapeutic agents. Non-choreic derangements in voluntary movement contribute to overall motor disability and are poorly addressed by current therapies. Pridopidine is a novel agent in the dopidine class believed to have 'state dependent' effects at dopamine receptors, thus show promise in the treatment of these disorders of voluntary movement.

AREAS COVERED

This review discusses the pharmacokinetics and pharmacodynamics of pridopidine and reviews clinical trials supporting development of the drug for HD. This information was culled from literature searches for dopidines, pridopidine, and HD experimental therapeutics in PubMed and at http://www.clinicaltrials.org .

EXPERT OPINION

There is a compelling need to discover new treatments for motor disability in HD, particularly for non-choreic motor symptoms. While pridopidine failed to achieve its primary efficacy outcomes in 2 large trials, reproducible effects on secondary motor outcomes have fueled an ongoing trial studying higher doses and more focused clinical endpoints. This and phase III trials will define define the utility of pridopidine for HD.