Prospects of statins in Parkinson disease

The role of statins in amyotrophic lateral sclerosis: protective or not?

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease of motor neurons characterized by muscle weakness, muscle twitching, and muscle wasting. ALS is regarded as the third-most frequent neurodegenerative disease, subsequent to Alzheimer's disease (AD) and Parkinson's disease (PD). The World Health Organization (WHO) in 2007 declared that prolonged use of statins may induce development of ALS-like syndrome and may increase ALS risk. Subsequently, different studies have implicated statins in the pathogenesis of ALS. In contrast, results from preclinical and clinical studies highlighted the protective role of statins against ALS neuropathology. Recently, meta-analyses and systematic reviews illustrated no association between long-term use of statins and ALS risk. These findings highlighted controversial points regarding the effects of statins on ALS pathogenesis and risk. The neuroprotective effects of statins against the development and progression of ALS may be mediated by regulating dyslipidemia and inflammatory changes. However, the mechanism for induction of ALS neuropathology by statins may be related to the dysregulation of liver X receptor signaling (LXR) signaling in the motor neurons and reduction of cholesterol, which has a neuroprotective effect against ALS neuropathology. Nevertheless, the exact role of statins on the pathogenesis of ALS was not fully elucidated. Therefore, this narrative review aims to discuss the role of statins in ALS neuropathology.

The effects of cholesterol and statins on Parkinson's neuropathology: a narrative review

Parkinson disease (PD) is chronic and progressive neurodegenerative disease of the brain characterized by motor symptoms including tremors, rigidity, postural instability, and bradykinesia. PD neuropathology is due to the progressive degeneration of dopaminergic neurons in the substantia nigra and accumulation of Lewy bodies in the survival neurons. The brain contains a largest amount of cholesterol which is mainly synthesized from astrocytes and glial cells. Cholesterol is intricate in the pathogenesis of PD and may be beneficial or deleterious. Therefore, there are controversial points concerning the role of cholesterol in PD neuropathology. In addition, cholesterol-lowering agents' statins can affect brain cholesterol. Different studies highlighted that statins, via inhibition of brain HMG-CoA, can affect neuronal integrity through suppression of neuronal cholesterol, which regulates synaptic plasticity and neurotransmitter release. Furthermore, statins affect the development and progression of different neurodegenerative diseases in bidirectional ways that could be beneficial or detrimental. Therefore, the objective of the present review was to clarify the double-sward effects of cholesterol and statins on PD neuropathology.

Nebulization of low-dose aspirin ameliorates Huntington's pathology in N171-82Q transgenic mice

Huntington Disease (HD), a devastating hereditary neurodegenerative disorder, is caused by expanded CAG trinucleotide repeats in the huntingtin gene (Htt) on chromosome 4. Currently, there is no effective therapy for HD. Although aspirin, acetylsalicylic acid, is one of the most widely-used analgesics throughout the world, it has some side effects. Even at low doses, oral aspirin can cause gastrointestinal symptoms, such as heartburn, upset stomach, or pain. Therefore, to bypass the direct exposure of aspirin to stomach, here, we described a new mode of use of aspirin and demonstrated that nebulization of low-dose of aspirin (10 μg/mouse/d=0.4 mg/kg body wt/d roughly equivalent to 28 mg/adult human/d) alleviated HD pathology in N171-82Q transgenic mice. Our immunohistochemical and western blot studies showed that daily aspirin nebulization significantly reduced glial activation, inflammation and huntingtin pathology in striatum and cortex of N171-82Q mice. Aspirin nebulization also protected transgenic mice from brain volume shrinkage and improved general motor behaviors. Collectively, these results highlight that nebulization of low-dose aspirin may have therapeutic potential in the treatment of HD.

The potential role of cholesterol in Parkinson's disease neuropathology: perpetrator or victim

Parkinson's disease (PD) is a neurodegenerative disease characterized by deposition of α-synuclein and aggregation of Lewy bodies. Cholesterol is involved with PD neuropathology in bidirectional ways that could be protective or harmful. Thus, the objective of the present review was to verify the potential role of cholesterol in PD neuropathology. Deregulation of ion channels and receptors induced by cholesterol alteration suggests a possible mechanism for the neuroprotective effects of cholesterol against PD development. However, high serum cholesterol level increases PD risk indirectly by 27-hydroxycholesterol which induces oxidative stress, inflammation, and apoptosis. Besides, hypercholesterolemia triggers the accumulation of cholesterol in macrophages and immune cells leading to the release of pro-inflammatory cytokines with progression of neuroinflammation subsequently. Additionally, cholesterol increases aggregation of α-synuclein and induces degeneration of dopaminergic neurons (DN) in the substantia nigra (SN). Hypercholesterolemia may lead to cellular Ca2+ overload causing synaptic and the development of neurodegeneration. In conclusion, cholesterol has bidirectional effects on PD neuropathology and might be protective or harmful.

The Involvement of Neuroinflammation in the Onset and Progression of Parkinson's Disease

Parkinson's disease is a neurodegenerative disease exhibiting the fastest growth in incidence in recent years. As with most neurodegenerative diseases, the pathophysiology is incompletely elucidated, but compelling evidence implicates inflammation, both in the central nervous system and in the periphery, in the initiation and progression of the disease, although it is not yet clear what triggers this inflammatory response and where it begins. Gut dysbiosis seems to be a likely candidate for the initiation of the systemic inflammation. The therapies in current use provide only symptomatic relief, but do not interfere with the disease progression. Nonetheless, animal models have shown promising results with therapies that target various vicious neuroinflammatory cascades. Translating these therapeutic strategies into clinical trials is still in its infancy, and a series of issues, such as the exact timing, identifying biomarkers able to identify Parkinson's disease in early and pre-symptomatic stages, or the proper indications of genetic testing in the population at large, will need to be settled in future guidelines.

Pros and cons for statins use and risk of Parkinson's disease: An updated perspective

Parkinson's disease (PD) is the second most frequent neurodegenerative brain disease (NBD) after Alzheimer's disease (AD). Statins are the most common lipid-lowering agents used in the management of dyslipidemia and the prevention of primary and secondary cardiovascular diseases (CVD) events. In addition, there is a controversial point regarding the role of serum lipids in the pathogenesis of PD. In this bargain, as statins reduce serum cholesterol so they affect the PD neuropathology in bidirectional ways either protective or harmful. Statins are not used in the management of PD, but they are frequently used in the cardiovascular disorders commonly associated with PD in the elderly population. Therefore, the use of statins in that population may affect PD outcomes. Concerning the potential role of statins on PD neuropathology, there are conflicts and controversies either protective against the development of PD or harmful by increasing the risk for the development of PD. Therefore, this review aimed to clarify the precise role of statins in PD regarding the pros and cons from published studies. Many studies suggest a protective role of statins against PD risk through the modulation of inflammatory and lysosomal signaling pathways. Nevertheless, other observations suggest that statin therapy may increase PD risk by diverse mechanisms including reduction of CoQ10. In conclusion, there are strong controversies regarding the protective role of statins in PD neuropathology. Therefore, retrospective and prospective studies are necessary in this regard.

Upregulation of DJ-1 in Dopaminergic Neurons by a Physically-Modified Saline: Implications for Parkinson's Disease

Parkinson's disease (PD) is the second most common neurodegenerative disorder in human and loss-of-functions DJ-1 mutations are associated with a familial form of early onset PD. Functionally, DJ-1 (PARK7), a neuroprotective protein, is known to support mitochondria and protect cells from oxidative stress. Mechanisms and agents by which the level of DJ-1 could be increased in the CNS are poorly described. RNS60 is a bioactive aqueous solution created by exposing normal saline to Taylor-Couette-Poiseuille flow under high oxygen pressure. Recently we have described neuroprotective, immunomodulatory and promyelinogenic properties of RNS60. Here we delineate that RNS60 is also capable of increasing the level of DJ-1 in mouse MN9D neuronal cells and primary dopaminergic neurons, highlighting another new neuroprotective effect of RNS60. While investigating the mechanism we found the presence of cAMP response element (CRE) in DJ-1 gene promoter and stimulation of CREB activation in neuronal cells by RNS60. Accordingly, RNS60 treatment increased the recruitment of CREB to the DJ-1 gene promoter in neuronal cells. Interestingly, RNS60 treatment also induced the enrollment of CREB-binding protein (CBP), but not the other histone acetyl transferase p300, to the promoter of DJ-1 gene. Moreover, knockdown of CREB by siRNA led to the inhibition of RNS60-mediated DJ-1 upregulation, indicating an important role of CREB in DJ-1 upregulation by RNS60. Together, these results indicate that RNS60 upregulates DJ-1 in neuronal cells via CREB-CBP pathway. It may be of benefit for PD and other neurodegenerative disorders.

Promising biomarkers and therapeutic targets for the management of Parkinson's disease: recent advancements and contemporary research

Parkinson's disease (PD) is one of the progressive neurological diseases which affect around 10 million population worldwide. The clinical manifestation of motor symptoms in PD patients appears later when most dopaminergic neurons have degenerated. Thus, for better management of PD, the development of accurate biomarkers for the early prognosis of PD is imperative. The present work will discuss the potential biomarkers from various attributes covering biochemical, microRNA, and neuroimaging aspects (α-synuclein, DJ-1, UCH-L1, β-glucocerebrosidase, BDNF, etc.) for diagnosis, recent development in PD management, and major limitations with current and conventional anti-Parkinson therapy. This manuscript summarizes potential biomarkers and therapeutic targets, based on available preclinical and clinical evidence, for better management of PD.

Emerging Therapeutic Strategies for Parkinson’s Disease and Future Prospects: A 2021 Update

Parkinson’s disease (PD) is a neurodegenerative disorder pathologically distinguished by degeneration of dopaminergic neurons in the substantia nigra pars compacta. Muscle rigidity, tremor, and bradykinesia are all clinical motor hallmarks of PD. Several pathways have been implicated in PD etiology, including mitochondrial dysfunction, impaired protein clearance, and neuroinflammation, but how these factors interact remains incompletely understood. Although many breakthroughs in PD therapy have been accomplished, there is currently no cure for PD, only trials to alleviate the related motor symptoms. To reduce or stop the clinical progression and mobility impairment, a disease-modifying approach that can directly target the etiology rather than offering symptomatic alleviation remains a major unmet clinical need in the management of PD. In this review, we briefly introduce current treatments and pathophysiology of PD. In addition, we address the novel innovative therapeutic targets for PD therapy, including α-synuclein, autophagy, neurodegeneration, neuroinflammation, and others. Several immunomodulatory approaches and stem cell research currently in clinical trials with PD patients are also discussed. Moreover, preclinical studies and clinical trials evaluating the efficacy of novel and repurposed therapeutic agents and their pragmatic applications with encouraging outcomes are summarized. Finally, molecular biomarkers under active investigation are presented as potentially valuable tools for early PD diagnosis.

Tremor and Rigidity in Patients with Parkinson's Disease: Emphasis on Epidemiology, Pathophysiology and Contributing Factors

Parkinson's disease (PD) is the second most prominent neurodegenerative movement disorder after Alzheimer's disease, involving 2-3% of the population aged above 65 years. This is mainly triggered by the depletion of dopaminergic neurons located in substantia nigra pars compacta (SNpc) in the region of basal ganglia. At present, diagnosis for symptoms of PD is clinical, contextual, unspecified and therapeutically incomprehensive. Analysis of various causes of PD is essential for an accurate examination of the disease. Among the different causes, such as tremors and rigidity, unresponsiveness to the current treatment approach contributes to mortality. In the present review article, we describe various key factors of pathogenesis and physiology associated with tremors and rigidity necessary for the treatment of PI (postural instability) in patients with PD. Additionally, several reports showing early tremor and rigidity causes, particularly age, cortex lesions, basal ganglia lesions, genetic abnormalities, weakened reflexes, nutrition, fear of fall, and altered biomechanics, have been explored. By summarizing the factors that contribute to the disease, histopathological studies can assess rigidity and tremor in PD. With a clear understanding of the contributing factors, various prospective studies can be done to assess the incidence of rigidity and tremors.

Cholesterol in Synaptic Vesicle Membranes Regulates the Vesicle-Binding, Function, and Aggregation of α-Synuclein

Loss of function and aggregation of the neuronal protein α-Synuclein (A-Syn) underlies the pathogenesis of Parkinson's disease (PD), and both the function and aggregation of this protein happen to be mediated via its binding to the synaptic vesicles (SVs) at the presynaptic termini. An essential constituent of SV membranes is cholesterol, with which A-Syn directly interacts while binding to membranes. Thus, cholesterol content in SV membranes is likely to affect the binding of A-Syn to these vesicles and consequently its functional and pathogenic behaviors. Interestingly, the dyshomeostasis of cholesterol has often been associated with PD, with reports linking both high and low cholesterol levels to an increased risk of neurodegeneration. Herein, using SV-mimicking liposomes containing increasing percentages of membrane cholesterol, we show (with mathematical interpretation) that the binding of A-Syn to synaptic-like vesicles is strongest in the presence of an optimum cholesterol content, which correlates to its maximum function and minimum aggregation. This implicates a minimum risk of neurodegeneration at optimum cholesterol levels and rationalizes the existing controversial relationship between cholesterol levels and PD. Increased membrane cholesterol was, however, found to protect against damage caused by aggregated A-Syn, complementing previous reports and portraying one advantage of high cholesterol over low.

Anti-Inflammatory Properties of Statin-Loaded Biodegradable Lecithin/Chitosan Nanoparticles: A Step Toward Nose-to-Brain Treatment of Neurodegenerative Diseases

Nasal delivery has been indicated as one of the most interesting alternative routes for the brain delivery of neuroprotective drugs. Nanocarriers have emerged as a promising strategy for the delivery of neurotherapeutics across the nasal epithelia. In this work, hybrid lecithin/chitosan nanoparticles (LCNs) were proposed as a drug delivery platform for the nasal administration of simvastatin (SVT) for the treatment of neuroinflammatory diseases. The impact of SVT nanoencapsulation on its transport across the nasal epithelium was investigated, as well as the efficacy of SVT-LCNs in suppressing cytokines release in a cellular model of neuroinflammation. Drug release studies were performed in simulated nasal fluids to investigate SVT release from the nanoparticles under conditions mimicking the physiological environment present in the nasal cavity. It was observed that interaction of nanoparticles with a simulated nasal mucus decreased nanoparticle drug release and/or slowed drug diffusion. On the other hand, it was demonstrated that two antibacterial enzymes commonly present in the nasal secretions, lysozyme and phospholipase A2, promoted drug release from the nanocarrier. Indeed, an enzyme-triggered drug release was observed even in the presence of mucus, with a 5-fold increase in drug release from LCNs. Moreover, chitosan-coated nanoparticles enhanced SVT permeation across a human cell model of the nasal epithelium (×11). The nanoformulation pharmacological activity was assessed using an accepted model of microglia, obtained by activating the human macrophage cell line THP-1 with the Escherichia coli–derived lipopolysaccharide (LPS) as the pro-inflammatory stimulus. SVT-LCNs were demonstrated to suppress the pro-inflammatory signaling more efficiently than the simple drug solution (−75% for IL-6 and −27% for TNF-α vs. −47% and −15% at 10 µM concentration for SVT-LCNs and SVT solution, respectively). Moreover, neither cellular toxicity nor pro-inflammatory responses were evidenced for the treatment with the blank nanoparticles even after 36 h of incubation, indicating a good biocompatibility of the nanomedicine components in vitro. Due to their biocompatibility and ability to promote drug release and absorption at the biointerface, hybrid LCNs appear to be an ideal carrier for achieving nose-to-brain delivery of poorly water-soluble drugs such as SVT.

Statins in Parkinson's Disease: Influence on Motor Progression

BACKGROUND

It has been speculated that stains are neuroprotective and are associated with a reduced risk of Parkinson's disease (PD), but only a few studies have investigated the influence of statins on the progression of PD.

OBJECTIVE

To evaluate whether long-term statin use may affect motor progression in a large cohort of de novo patients with PD.

METHODS

We conducted a 4-year retrospective observational cohort study to assess patients with PD. The patients were consecutively recruited from a single tertiary center between January 2015 and January 2017. Information on motor function was obtained using the MDS-Unified Parkinson Disease Rating Scale (UPDRS)-III and all subjects were extensively characterized, including information about lifestyle habits, cardiovascular risk factors and cholesterol blood levels.

RESULTS

Of the 181 participants included in the study, 104 patients were evaluated for eligibility (42 patients were exposed to statin therapies and 62 were not treated with statins). They presented similar scores in UPDRS III at baseline but the statin users had a lower motor impairment at 4 years compared to non-user PD patients. Additionally, statin treatment resulted in slower progression of the rigidity score of UPDRS over 4 years. No other significant differences were observed between PD patients with and without statins.

CONCLUSION

Early PD patients with long-term statin usage showed lower motor deterioration after 4 years of disease duration compared with patients not taking statins at diagnosis, suggesting a possible influence of statins on disease progression in PD. Further investigation is warranted to understand the potential beneficial effects of statin treatment on clinical symptoms in PD.

Novel therapeutic approaches for Parkinson's disease by targeting brain cholesterol homeostasis

OBJECTIVES

Human brain is composed of 25% of the cholesterol & any dysfunction in brain cholesterol homeostasis contributes to neurodegenerative disorders such as Parkinson, Alzheimer's, Huntington's disease, etc. A growing literature indicates that alteration in neurotransmission & brain cholesterol metabolism takes place in the early stage of the disease. The current paper summarizes the role of cholesterol & its homeostasis in the pathophysiology of Parkinson's disease.

KEY FINDINGS

Literature findings suggest the possible role of lipids such as oxysterols, lipoproteins, etc. in Parkinson's disease pathophysiology. Cholesterol performs a diverse role in the brain but any deviation in its levels leads to neurodegeneration. Dysregulation of lipid caused by oxidative stress & inflammation leads to α-synuclein trafficking which contributes to Parkinson's disease progression. Also, α-synuclein by binding to membrane lipid forms lipid-protein complex & results in its aggregation. Different targets such as Phospholipase A2, Stearoyl-CoA desaturase enzyme, proprotein convertase subtilisin/kexin type 9, etc. have been identified as a potential novel approach for Parkinson's disease treatment.

SUMMARY

In the current review, we have discussed the possible molecular role of cholesterol homeostasis in Parkinson's disease progression. We also identified potential therapeutic targets that need to be evaluated clinically for the development of Parkinson's treatment.

Role of RhoA-ROCK signaling in Parkinson's disease

Parkinson's disease (PD) is a complex and widespread neurodegenerative disease characterized by depletion of midbrain dopaminergic (DA) neurons. Key issues are the development of therapies that can stop or reverse the disease progression, identification of dependable biomarkers, and better understanding of the pathophysiological mechanisms of PD. RhoA-ROCK signals appear to have an important role in PD symptoms, making it a possible approach for PD treatment strategies. Activation of RhoA-ROCK (Rho-associated coiled-coil containing protein kinase) appears to stimulate various PD risk factors including aggregation of alpha-synuclein (αSyn), dysregulation of autophagy, and activation of apoptosis. This manuscript reviews current updates about the biology and function of the RhoA-ROCK pathway and discusses the possible role of this signaling pathway in causing the pathogenesis of PD. We conclude that inhibition of the RhoA-ROCK signaling pathway may have high translational potential and could be a promising therapeutic target in PD.

Metachromatic Leukodystrophy: Diagnosis, Modeling, and Treatment Approaches

Metachromatic leukodystrophy is a lysosomal storage disease, which is characterized by damage of the myelin sheath that covers most of nerve fibers of the central and peripheral nervous systems. The disease occurs due to a deficiency of the lysosomal enzyme arylsulfatase A (ARSA) or its sphingolipid activator protein B (SapB) and it clinically manifests as progressive motor and cognitive deficiency. ARSA and SapB protein deficiency are caused by mutations in the ARSA and PSAP genes, respectively. The severity of clinical course in metachromatic leukodystrophy is determined by the residual ARSA activity, depending on the type of mutation. Currently, there is no effective treatment for this disease. Clinical cases of bone marrow or cord blood transplantation have been reported, however the therapeutic effectiveness of these methods remains insufficient to prevent aggravation of neurological disorders. Encouraging results have been obtained using gene therapy for delivering the wild-type ARSA gene using vectors based on various serotypes of adeno-associated viruses, as well as using mesenchymal stem cells and combined gene-cell therapy. This review discusses therapeutic strategies for the treatment of metachromatic leukodystrophy, as well as diagnostic methods and modeling of this pathology in animals to evaluate the effectiveness of new therapies.

Blood-Brain Barrier: More Contributor to Disruption of Central Nervous System Homeostasis Than Victim in Neurological Disorders

The blood-brain barrier (BBB) is a dynamic but solid shield in the cerebral microvascular system. It plays a pivotal role in maintaining central nervous system (CNS) homeostasis by regulating the exchange of materials between the circulation and the brain and protects the neural tissue from neurotoxic components as well as pathogens. Here, we discuss the development of the BBB in physiological conditions and then focus on the role of the BBB in cerebrovascular disease, including acute ischemic stroke and intracerebral hemorrhage, and neurodegenerative disorders, such as Alzheimer's disease (AD), Parkinson's disease (PD), and multiple sclerosis (MS). Finally, we summarize recent advancements in the development of therapies targeting the BBB and outline future directions and outstanding questions in the field. We propose that BBB dysfunction not only results from, but is causal in the pathogenesis of neurological disorders; the BBB is more a contributor to the disruption of CNS homeostasis than a victim in neurological disorders.

A medicinal chemistry perspective of drug repositioning: Recent advances and challenges in drug discovery

Drug repurposing is a strategy consisting of finding new indications for already known marketed drugs used in various clinical settings or highly characterized compounds despite they can be failed drugs. Recently, it emerges as an alternative approach for the rapid identification and development of new pharmaceuticals for various rare and complex diseases for which lack the effective drug treatments. The success rate of drugs repurposing approach accounts for approximately 30% of new FDA approved drugs and vaccines in recent years. This review focuses on the status of drugs repurposing approach for various diseases including skin diseases, infective, inflammatory, cancer, and neurodegenerative diseases. Efforts have been made to provide structural features and mode of actions of drugs.

A systematic review and meta-analysis of serum cholesterol and triglyceride levels in patients with Parkinson's disease

Objectives

Numerous studies have reported that lipid metabolic abnormalities may play an important role in the development of Parkinson’s disease (PD), with mixed results. This meta-analysis aims to systematically assess the relationship between serum cholesterol or triglyceride and the PD risk and to further determine the role of dyslipidemia in potential predictive value.

Methods

This research systematically consulted and screened observational studies to evaluate the association of serum lipids with the risk of PD as of April 01, 2020 based on the inclusion and exclusion criteria. Two researchers screened and extracted the data independently. Then this article summarized the characteristics of all clinical studies and collected the corresponding data to perform pooled and sensitivity analyses. The meta-analysis was performed by using the RevMan 5.3 software after data extraction, quality assessment and analysis of publication bias.

Results

Twenty-one related studies (13 case-control and 8 cohort studies) were selected with a total of 980,180 subjects, including 11,188 PD patients. Meta-analysis showed that higher levels of serum triglyceride (S-TG) [standard mean different (SMD) = − 0.26 (95% confidence interval (CI): − 0.39 to − 0.13, p<0.00001), relative risk (RR) = 0.67 (95% CI: 0.60 to 0.75, p<0.00001)] could be considered as protective factors for the pathogenesis of PD. However, there was no significant association between serum high density lipoprotein cholesterol (S-HDL) and the risk of PD. Meanwhile, serum low density lipoprotein cholesterol (S-LDL) [SMD = -0.26 (95% CI: − 0.43 to − 0.07, p = 0.006), RR = 0.76 (95% CI: 0.59 to 0.97, p = 0.03)] and serum total cholesterol (S-TC) levels [SMD = -0.21 (95% CI: − 0.33 to − 0.10, p = 0.0002), RR = 0.86 (95% CI: 0.77 to 0.97, p = 0.01)] were negatively associated with PD risk.

Conclusions

This systematic review suggests that elevated serum levels of TG, LDL and TC may be protective factors for the pathogenesis of PD. Further longitudinal and well-designed prospective studies with a large sample size are needed to confirm the findings in this meta-analysis.

High-Cholesterol Diet Decreases the Level of Phosphatidylinositol 4,5-Bisphosphate by Enhancing the Expression of Phospholipase C (PLCβ1) in Rat Brain

Cholesterol is a critical component of eukaryotic membranes, where it contributes to regulating transmembrane signaling, cell-cell interaction, and ion transport. Dysregulation of cholesterol levels in the brain may induce neurodegenerative diseases, such as Alzheimer's disease, Parkinson disease, and Huntington disease. We previously reported that augmenting membrane cholesterol level regulates ion channels by decreasing the level of phosphatidylinositol 4,5-bisphosphate (PIP₂), which is closely related to β-amyloid (Aβ) production. In addition, cholesterol enrichment decreased PIP₂ levels by increasing the expression of the β1 isoform of phospholipase C (PLC) in cultured cells. In this study, we examined the effect of a high-cholesterol diet on phospholipase C (PLCβ1) expression and PIP₂ levels in rat brain. PIP₂ levels were decreased in the cerebral cortex in rats on a high-cholesterol diet. Levels of PLCβ1 expression correlated with PIP₂ levels. However, cholesterol and PIP₂ levels were not correlated, suggesting that PIP₂ level is regulated by cholesterol via PLCβ1 expression in the brain. Thus, there exists cross talk between cholesterol and PIP₂ that could contribute to the pathogenesis of neurodegenerative diseases.

Understanding the links between cardiovascular disease and Parkinson's disease

Studies investigating the associations between genetic or environmental factors and Parkinson's disease (PD) have uncovered a number of factors shared with cardiovascular disease, either as risk factors or manifestations of cardiovascular disease itself. Older age, male sex, and possibly type 2 diabetes are examples. On the other hand, coffee consumption and physical activity are each associated with a lower risk of both PD and cardiovascular disease. This observation raises questions about the underlying pathophysiological links between cardiovascular disease and PD. There is evidence for common mechanisms in the areas of glucose metabolism, cellular stress, lipid metabolism, and inflammation. On the other hand, smoking and total/low-density lipoprotein cholesterol appear to have opposite associations with cardiovascular disease and PD. Thus, it is uncertain whether the treatment of cardiovascular risk factors will impact on the onset or progression of PD. The available data suggest that a nuanced approach is necessary to manage risk factors such as cholesterol levels once the associations are better understood. Ultimately, the choice of therapy may be tailored to a patient's comorbidity profile. This review presents the epidemiological evidence for both concordant and discordant associations between cardiovascular disease and PD, discusses the cellular and metabolic processes that may underlie these links, and explores the implications this has for patient care and future research. © 2019 International Parkinson and Movement Disorder Society.

Nose-to-brain co-delivery of repurposed simvastatin and BDNF synergistically attenuates LPS-induced neuroinflammation

A therapeutic strategy that can combat the multifaceted nature of neuroinflammation pathology was investigated. Thus, we fabricated PEG-PdLLA polymersomes and evaluated the efficacy in co-delivery of simvastatin (Sim, as a repurposed anti-inflammatory agent) with brain derived neurotrophic factor (BDNF, as an exogeneous trophic factor supplementation). Using LPS model of neuroinflammation, intranasal administration of combination drug-loaded polymersomes (containing both Sim and BDNF; Sim-BDNF-Ps) markedly down-regulated brain levels of cytokines compared to free drug and single-drug-loaded polymersomes. Further, Sim-BDNF-Ps effectively replenished brain level of BDNF that was depleted following neuroinflammation, resulting in a 2-fold BDNF increase versus untreated LPS control group. We found out that the efficiency of the combination drug-loaded polymersomes to suppress microglia activation in brain regions followed the order: frontal cortex > striatum > hippocampus. Our findings indicated that Sim-BDNF-Ps could effectively inhibit microglial-mediated inflammation as well as potentially resolve the neurotoxic microenvironment that is often associated with neuroinflammation.

Simvastatin as a neuroprotective treatment for Parkinson's disease (PD STAT): protocol for a double-blind, randomised, placebo-controlled futility study

INTRODUCTION

Parkinson's disease (PD) is a progressive neurodegenerative condition affecting approximately 185,000 people in the UK. No drug has been proven to slow disease progression. Epidemiological and pre-clinical data support simvastatin, a widely used cholesterol-lowering drug with a well-established safety profile, having neuroprotective properties. The aim of this study (Simvastatin as a neuroprotective treatment for PD (PD STAT)) is to determine whether simvastatin has the potential to slow PD progression. The study is part of the International Linked Clinical Trials initiative coordinated by The Cure Parkinson's Trust. This paper describes the protocol for the PD STAT study.

METHODS AND ANALYSIS

PD STAT is a double-blind, randomised, placebo-controlled, multi-centre, parallel group, futility trial in patients with PD of mild-moderate severity. 235 participants have been recruited and randomly allocated in a 1:1 ratio to receive either oral simvastatin or matched placebo. Treatment involves a 1-month low-dose phase (40 mg daily), followed by a 23-month high-dose phase (80 mg daily) and ends with a 2-month washout period. Participants are reviewed at clinic visits at 1 month, 6, 12, 18, 24 and 26 months post-baseline, with interim telephone follow-up to monitor for adverse events.The primary outcome is the change in the Movement Disorder Society Unified Parkinson's Disease Rating Scale part III motor subscale score in the practically defined OFF medication state (OFF state) between baseline and 24 months. Primary analysis will be on a modified intention to treat basis and will include only those participants who progress to the high-dose phase of the study.

ETHICS AND DISSEMINATION

The protocol has been approved by the North East-Newcastle and North Tyneside 2 Research Ethics Committee. The results will be disseminated via research articles in peer-reviewed journals and presentations at local, national and international scientific meetings, as well as disseminated via patient groups, websites and networks. A summary of the study findings will be posted to participants at the end of the study.

TRIAL REGISTRATION

ISRCTN16108482 (prospectively registered); EudraCT 2015-000148-40; ClinicalTrials.gov NCT02787590; Pre-results.

RANTES-induced invasion of Th17 cells into substantia nigra potentiates dopaminergic cell loss in MPTP mouse model of Parkinson's disease

Although Parkinson's disease (PD) is a progressive neurodegenerative disease, the disease does not progress or persist in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse model, the most common animal model of PD. Recently, we have described that supplementation of regulated on activation, normal T cell expressed and secreted (RANTES), a chemokine known to drive infiltration of T cells, induces persistent nigrostriatal pathology in MPTP mouse model. However, which particular T cell subsets are recruited to the substantia nigra (SN) by RANTES is not known. Here, by adoptive transfer of different subset of T cells from tomato red transgenic mice to MPTP-intoxicated immunodeficient Rag1^-/- mice, we describe that invasion of Th17 cells into the SN is stimulated by exogenous RANTES administration. On the other hand, RANTES supplementation remained unable to influence the infiltration of Th1 and Tregs into the SN of MPTP-insulted Rag1^-/- mice. Accordingly, RANTES supplementation increased MPTP-induced TH cell loss in Rag1^-/-mice receiving Th17, but neither Th1 nor Tregs. RANTES-mediated aggravation of nigral TH neurons also paralleled with significant DA loss in striatum and locomotor deficits in MPTP-intoxicated Rag1^-/- mice receiving Th17 cells. Finally, we demonstrate that levels of IL-17 (a Th17-specific cytokine) and RANTES are higher in serum of PD patients than age-matched controls and that RANTES positively correlated with IL-17 in serum of PD patients. Together, these results highlight the importance of RANTES-Th17 pathway in progressive dopaminergic neuronal loss and associated PD pathology.

The role of NOX inhibitors in neurodegenerative diseases

Oxidative stress is a key player in both chronic and acute brain disease due to the higher metabolic demand of the brain. Among the producers of free radicals, NADPH-oxidase (NOX) is a major contributor to oxidative stress in neurological disorders. In the brain, the superoxide produced by NOX is mainly found in leukocytes. However, recent studies have reported that it can be found in several other cell types. NOX has been reported to regulate neuronal signaling, memory processing, and central cardiovascular homeostasis. However, overproduction of NOX can contribute to neurotoxicity, CNS degeneration, and cardiovascular disorders. Regarding the above functions, NOX has been shown to play a crucial role in chronic CNS diseases like Parkinson's disease (PD), Alzheimer's disease (AD), Huntington's disease (HD), multiple sclerosis (MS), and amyotrophic lateral sclerosis (ALS), and in acute CNS disorders such as stroke, spinal cord injury, traumatic brain injury (TBI), and related cerebrovascular diseases. NOX is a multi-subunit complex consisting of two membrane-associated and four cytosolic subunits. Thus, in recent years, inhibition of NOX activity has drawn a great deal of attention from researchers in the field of treating chronic and acute CNS disorders and preventing secondary complications. Mounting evidence has shown that NOX inhibition is neuroprotective and that inhibiting NOX in circulating immune cells can improve neurological disease conditions. This review summarizes recent studies on the therapeutic effects and pharmacological strategies regarding NOX inhibitors in chronic and acute brain diseases and focuses on the hurdles that should be overcome before their clinical implementation.

Low-Dose Maraviroc, an Antiretroviral Drug, Attenuates the Infiltration of T Cells into the Central Nervous System and Protects the Nigrostriatum in Hemiparkinsonian Monkeys

Parkinson's disease (PD) is the most common neurodegenerative movement disorder in humans. Despite intense investigation, no effective therapy is available to stop the progression of this disease. It is becoming clear that both innate and adaptive immune responses are active in PD. Accordingly, we have reported a marked increase in RANTES and eotaxin, chemokines that are involved in T cell trafficking, in vivo in the substantia nigra (SN) and the serum of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-intoxicated hemiparkinsonian monkeys. Because RANTES and eotaxin share a common receptor, CCR5, we examined the efficacy of maraviroc, an inhibitor of CCR5 and a Food and Drug Administration-approved drug against HIV infection, in hemiparkinsonian rhesus monkeys. First, we found glial limitans injury, loss of GFAP immunostaining, and infiltration of T cells across the endothelial monolayer in SN of hemiparkinsonian monkeys. However, oral administration of a low dose of maraviroc protected glia limitans partially, maintained the integrity of endothelial monolayer, reduced the infiltration of T cells, attenuated neuroinflammation, and decreased α-synucleinopathy in the SN. Accordingly, maraviroc treatment also protected both the nigrostriatal axis and neurotransmitters and improved motor functions in hemiparkinsonian monkeys. These results suggest that low-dose maraviroc and other CCR5 antagonists may be helpful for PD patients.

Activation of Peroxisome Proliferator-Activated Receptor-α Increases the Expression of Nuclear Receptor Related 1 Protein (Nurr1) in Dopaminergic Neurons

Nuclear receptor related 1 protein (Nurr1) is an important transcription factor required for differentiation and maintenance of midbrain dopaminergic (DA) neurons. Since decrease in Nurr1 function either due to diminished expression or rare mutation is associated with Parkinson's disease (PD), upregulation of Nurr1 may be beneficial for PD. However, such mechanisms are poorly understood. This study underlines the importance of peroxisome proliferator-activated receptor (PPAR)α in controlling the transcription of Nurr1. Our mRNA analyses followed by different immunoassays clearly indicated that PPARα agonist gemfibrozil strongly upregulated the expression of Nurr1 in wild-type, but not PPARα^-/-, DA neurons. Moreover, identification of conserved PPRE in the promoter of Nurr1 gene followed by chromatin immunoprecipitation analysis, PPRE luciferase assay, and manipulation of Nurr1 gene by viral transduction of different PPARα plasmids confirmed that PPARα was indeed involved in the expression of Nurr1. Finally, oral administration of gemfibrozil increased Nurr1 expression in vivo in nigra of wild-type, but not PPARα^-/-, mice identifying PPARα as a novel regulator of Nurr1 expression and associated protection of DA neurons.

Lipids at the Crossroad of α-Synuclein Function and Dysfunction: Biological and Pathological Implications

Since its discovery, the study of the biological role of α-synuclein and its pathological implications has been the subject of increasing interest. The propensity to adopt different conformational states governing its aggregation and fibrillation makes this small 14-kDa cytosolic protein one of the main etiologic factors associated with degenerative disorders known as synucleinopathies. The structure, function, and toxicity of α-synuclein and the possibility of different therapeutic approaches to target the protein have been extensively investigated and reviewed. One intriguing characteristic of α-synuclein is the different ways in which it interacts with lipids. Though in-depth studies have been carried out in this field, the information they have produced is puzzling and the precise role of lipids in α-synuclein biology and pathology and vice versa is still largely unknown. Here we provide an overview and discussion of the main findings relating to α-synuclein/lipid interaction and its involvement in the modulation of lipid metabolism and signaling.

Effect of statins on Parkinson's disease: A systematic review and meta-analysis

BACKGROUND

Statins have key lipid-lowering, anti-inflammatory, and anti-oxidative effects. However, it remains unclear whether statins are beneficial to patients with Parkinson's disease (PD). This study aimed to evaluate the relationship between statins and PD through a systematic review.

METHODS

This study adhered to the guideline of Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). Potentially relevant case-control or cohort studies published before March 2018 were identified by searching the MEDLINE (PubMed), EMBASE (OVID), CENTRAL (Cochrane Library), CNKI, WANGANG, VIP, CBM, CMCC, Clinicaltrials.gov, ProQuest, Opengray, and ISI Proceedings databases and conducting a manual search. Summarized relative risks (RRs) and 95% confidence intervals (CIs) were calculated using a fixed effect model. Sensitivity and subgroup analyses were also performed.

RESULTS

The meta-analysis included 17 studies (3,845,303 patients; 8 case-control and 9 cohort studies), including 5 articles not cited by other studies. We searched the Chinese database, but unfortunately, no Chinese literature can be included in the study. Briefly, statins could decrease the risk of PD, with a summary OR of 0.92 (95% CI: 0.86-0.99). A sensitivity analysis demonstrated the robustness of the results. Subgroup analyses revealed heterogeneity across the studies in terms of subject race, study type, reporting style, quality, statins type, and time for taking statins.

CONCLUSION

Our study provides evidence that statins, especially atorvastatin, can reduce the risk of PD. Different time of statins using has different effects on PD. However, additional randomized controlled trials and observational studies are needed to confirm this conclusion.

REGISTRATION ID

PROSPERO CRD: 42018095580.

Statins: Old drugs as new therapy for liver diseases?

In addition to lowering cholesterol levels, statins have pleiotropic effects, particularly anti-inflammatory, antiangiogenic, and antifibrotic, that may be beneficial in some chronic inflammatory conditions. Statins have only recently been investigated as a potential treatment option in chronic liver diseases because of concerns related to their safety in patients with impaired liver function. A number of experimental studies in animal models of liver diseases have shown that statins decrease hepatic inflammation, fibrogenesis and portal pressure. In addition, retrospective cohort studies in large populations of patients with cirrhosis and pre-cirrhotic conditions have shown that treatment with statins, with the purpose of decreasing high cholesterol levels, was associated with a reduced risk of disease progression, hepatic decompensation, hepatocellular carcinoma development, and death. These beneficial effects persisted after adjustment for disease severity and other potential confounders. Finally, a few randomised controlled trials have shown that treatment with simvastatin decreases portal pressure (two studies) and mortality (one study). Statin treatment was generally well tolerated but a few patients developed severe side effects, particularly rhabdomyolysis. Despite these promising beneficial effects, further randomised controlled trials in large series of patients with hard clinical endpoints should be performed before statins can be recommended for use in clinical practice.

Drug Repurposing in Parkinson's Disease

The development of an intervention to slow or halt disease progression remains the greatest unmet therapeutic need in Parkinson's disease. Given the number of failures of various novel interventions in disease-modifying clinical trials in combination with the ever-increasing costs and lengthy processes for drug development, attention is being turned to utilizing existing compounds approved for other indications as novel treatments in Parkinson's disease. Advances in rational and systemic drug repurposing have identified a number of drugs with potential benefits for Parkinson's disease pathology and offer a potentially quicker route to drug discovery. Here, we review the safety and potential efficacy of the most promising candidates repurposed as potential disease-modifying treatments for Parkinson's disease in the advanced stages of clinical testing.

RNAseq analysis of hippocampal microglia after kainic acid-induced seizures

Microglia have been shown to be of critical importance to the progression of temporal lobe epilepsy. However, the broad transcriptional changes that these cells undergo following seizure induction is not well understood. As such, we utilized RNAseq analysis upon microglia isolated from the hippocampus to determine expression pattern alterations following kainic acid induced seizure. We determined that microglia undergo dramatic changes to their expression patterns, particularly with regard to mitochondrial activity and metabolism. We also observed that microglia initiate immunological activity, specifically increasing interferon beta responsiveness. Our results provide novel insights into microglia transcriptional regulation following acute seizures and suggest potential therapeutic targets specifically in microglia for the treatment of seizures and epilepsy.

Simvastatin as a Potential Disease-Modifying Therapy for Patients with Parkinson's Disease: Rationale for Clinical Trial, and Current Progress

Many now believe the holy grail for the next stage of therapeutic advance surrounds the development of disease-modifying approaches aimed at intercepting the year-on-year neurodegenerative decline experienced by most patients with Parkinson’s disease (PD). Based on recommendations of an international committee of experts who are currently bringing multiple, potentially disease-modifying, PD therapeutics into long-term neuroprotective PD trials, a clinical trial involving 198 patients is underway to determine whether Simvastatin provides protection against chronic neurodegeneration. Statins are widely used to reduce cardiovascular risk, and act as competitive inhibitors of HMG-CoA reductase. It is also known that statins serve as ligands for PPARα, a known arbiter for mitochondrial size and number. Statins possess multiple cholesterol-independent biochemical mechanisms of action, many of which offer neuroprotective potential (suppression of proinflammatory molecules & microglial activation, stimulation of endothelial nitric oxide synthase, inhibition of oxidative stress, attenuation of α-synuclein aggregation, modulation of adaptive immunity, and increased expression of neurotrophic factors). We describe the biochemical, physiological and pharmaceutical credentials that continue to underpin the rationale for taking Simvastatin into a disease-modifying trial in PD patients. While unrelated to the Simvastatin trial (because this conducted in patients who already have PD), we discuss conflicting epidemiological studies which variously suggest that statin use for cardiovascular prophylaxis may increase or decrease risk of developing PD. Finally, since so few disease-modifying PD trials have ever been launched (compared to those of symptomatic therapies), we discuss the rationale of the trial structure we have adopted, decisions made, and lessons learnt so far.

The beneficial effects of HMG-CoA reductase inhibitors in the processes of neurodegeneration

Statins, cholesterol lowering drugs, have been demonstrated to exert beneficial effects in other conditions such as primary and progressing neurodegenerative diseases beyond their original role. Observation that statins ameliorate the neurodegenerative diseases such as Parkinson's disease (PD), Alzheimer's disease (AD), multiple sclerosis (MS) and cerebral ischemic stroke, the neuroprotective effects of these drugs are thought to be linked to their anti-inflammatory, anti-oxidative, and anti-excitotoxic properties. Despite the voluminous literature on the clinical advantages of 3-hydroxy-3-methylglutaryl Co-enzyme A reductase (HMGCR) inhibitors (statins) in cardiovascular system, the neuroprotective effects and the underlying mechanisms are little understood. Hence, the present review tries to provide a critical overview on the statin-induced neuroprotection, which are presumed to be associated with the ability to reduce cholesterol, Amyloid-β and apolipoprotein E (ApoE) levels, decrease reactive oxygen and nitrogen species (ROS and RNS) formation, inhibit excitotoxicity, modulate matrix metalloproteinases (MMPs), stimulate endothelial nitric oxide synthase (eNOS), and increase cerebral blood perfusion. This review is also aimed to illustrate that statins protect neurons against the neuro-inflammatory processes through balancing pro-inflammatory/anti-inflammatory cytokines. Ultimately, the beneficial role of statins in ameliorating the development of PD, AD, MS and cerebral ischemic stroke has been separately reviewed.

Simvastatin ameliorates memory impairment and neurotoxicity in streptozotocin-induced diabetic mice

Diabetes comes with an additional burden of moderate to severe hyperlipidemia, but little is known about the effects of lipid-lowering therapy on diabetic complications such as diabetes-associated cognitive decline. Herein we investigated the effects of statins on memory impairment and neurotoxicity in streptozotocin-induced diabetic mice. Our data indicated that oral administration of simvastatin at 10 or 20mg/kg for 4weeks significantly ameliorated diabetes-associated memory impairment reflected by performance better in the Morris water maze and Y-maze tests. The further study showed that these treatments caused significant increase of peroxisome proliferator-activated receptors gamma and decrease of NF-κB p65 in nucleus of hippocampus and cortex, and ameliorated neuroinflammatory response as evidenced by less Iba-1-positive cells and lower inflammatory mediators including IL-1β, IL-6 and TNF-α as well as suppressed neuronal apoptosis as indicated by decreased TUNEL-positive cells, increased ratio of Bcl-2/Bax and decreased caspase-3 activity in the hippocampus and cortex. Moreover, simvastatin pronouncedly attenuated amyloidogenesis by decreasing amyloid-β, amyloid precursor protein (APP) and beta-site APP cleaving enzyme-1. As expected, treated with simvastatin, the diabetic mice exhibited significant improvement of hyperlipidemia rather than hyperglycemia. Our findings disclosed novel therapeutic potential of simvastatin for the diabetes-associated cognitive impairment.

Induction of Adaptive Immunity Leads to Nigrostriatal Disease Progression in MPTP Mouse Model of Parkinson's Disease

Although the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse model is the most widely used animal model for Parkinson's disease (PD), it is known that nigrostriatal pathologies do not persist in the acute MPTP mouse model. This study highlights the importance of adaptive immunity in driving persistent and progressive disease in acute MPTP-intoxicated mice. Although marked infiltration of T cells into the nigra was found on 1 d of MPTP insult, T cell infiltration decreased afterward, becoming normal on 30 d of insult. Interestingly, twice-weekly supplementation of RANTES and eotaxin, chemokines that are involved in T cell trafficking, drove continuous T cell infiltration to the nigra and incessant glial inflammation. Supplementation of RANTES and eotaxin was also associated with the induction of nigral α-synuclein pathology, persistent loss of dopaminergic neurons and striatal neurotransmitters, and continuous impairment of motor functions in MPTP-intoxicated mice. In contrast, supplementation of TNF-α and IL-1β, widely studied proinflammatory cytokines, did not induce persistent disease in MPTP-insulted mice. Our results suggest that induction of adaptive immunity by RANTES and eotaxin could hold the key for driving persistent nigrostriatal pathologies in the MPTP mouse model, and that targeting these factors may halt disease progression in PD patients.

Current insights into pathogenesis of Parkinson's disease: Approach to mevalonate pathway and protective role of statins

Although Parkinson's disease (PD) is considered as the second most common life threatening age-related neurodegenerative disorder, but the underlying mechanisms for pathogenesis of PD are remained to be fully found. However, a complex relationship between genetic and environmental predisposing factors are involved in progression of PD. Dopaminergic neuronal cell death caused by mutations and accumulation of α-synuclein in Lewy bodies and neurites was suggested as the main strategy for PD, but current studies have paid attention to the role of mevalonate pathway in incidence of neurodegenerative diseases including PD. The discovery may change the therapeutic protocols from symptomatic treatment by dopamine precursors and agonists to neurodegenerative process halting drugs. Moreover, the downstream metabolites of mevalonate pathway may be used as diagnostic biomarkers for early diagnosis of PD. Statins, as cholesterol lowering drugs, may ameliorate the enzyme complex dysfunction, a key step in the progression of the neurodegenerative disorders, oxidative stress-induced damage and neuro-inflammation. Statins exert the neuroprotective effects on striatal dopaminergic neurons through blocking the mevalonate pathway. In the present review, we have focused on the new approaches to pathogenesis of PD regarding to mevalonate pathway, in addition to the previous understood mechanisms for the disease. It tries to elucidate the novel findings about PD for the development of future diagnostic and therapeutic strategies. Moreover, we explain the controversial role of statins in improvement or progression of PD and the position of these drugs in neuroprotection in PD patients.

Impact of high cholesterol in a Parkinson's disease model: Prevention of lysosomal leakage versus stimulation of α-synuclein aggregation

Parkinson's disease is characterized by accumulation of intraneuronal cytoplasmic inclusions, Lewy bodies, which mainly consist of aggregated α-synuclein. Controversies exist as to whether high blood cholesterol is a risk factor for the development of the disease and whether statin treatment could have a protective effect. Using a model system of BE(2)-M17 neuroblastoma cells treated with the neurotoxin 1-methyl-4-phenylpyridinium (MPP⁺), we found that MPP⁺-induced cell death was accompanied by cholesterol accumulation in a lysosomal-like pattern in pre-apoptotic cells. To study the effects of lysosomal cholesterol accumulation, we increased lysosomal cholesterol through pre-treatment with U18666A and found delayed leakage of lysosomal contents into the cytosol, which reduced cell death. This suggests that increased lysosomal cholesterol is a stress response mechanism to protect lysosomal membrane integrity in response to early apoptotic stress. However, high cholesterol also stimulated the accumulation of α-synuclein. Treatment with the cholesterol-lowering drug lovastatin reduced MPP⁺-induced cell death by inhibiting the production of reactive oxygen species, but did not prevent lysosomal cholesterol increase nor affect α-synuclein accumulation. Our study indicates a dual role of high cholesterol in Parkinson's disease, in which it acts both as a protector against lysosomal membrane permeabilization and as a stimulator of α-synuclein accumulation.

Current and Emerging Uses of Statins in Clinical Therapeutics: A Review

Statins, a class of cholesterol-lowering medications that inhibit 3-hydroxy-3-methyl-glutaryl-coenzyme A reductase, are commonly administered to treat atherosclerotic cardiovascular disease. Statin use may expand considerably given its potential for treating an array of cholesterol-independent diseases. However, the lack of conclusive evidence supporting these emerging therapeutic uses of statins brings to the fore a number of unanswered questions including uncertainties regarding patient-to-patient variability in response to statins, the most appropriate statin to be used for the desired effect, and the efficacy of statins in treating cholesterol-independent diseases. In this review, the adverse effects, costs, and drug–drug and drug–food interactions associated with statin use are presented. Furthermore, we discuss the pleiotropic effects associated with statins with regard to the onset and progression of autoimmune and inflammatory diseases, cancer, neurodegenerative disorders, strokes, bacterial infections, and human immunodeficiency virus. Understanding these issues will improve the prognosis of patients who are administered statins and potentially expand our ability to treat a wide variety of diseases.

Melatoninergic System in Parkinson's Disease: From Neuroprotection to the Management of Motor and Nonmotor Symptoms

Melatonin is synthesized by several tissues besides the pineal gland, and beyond its regulatory effects in light-dark cycle, melatonin is a hormone with neuroprotective, anti-inflammatory, and antioxidant properties. Melatonin acts as a free-radical scavenger, reducing reactive species and improving mitochondrial homeostasis. Melatonin also regulates the expression of neurotrophins that are involved in the survival of dopaminergic neurons and reduces α-synuclein aggregation, thus protecting the dopaminergic system against damage. The unbalance of pineal melatonin synthesis can predispose the organism to inflammatory and neurodegenerative diseases such as Parkinson's disease (PD). The aim of this review is to summarize the knowledge about the potential role of the melatoninergic system in the pathogenesis and treatment of PD. The literature reviewed here indicates that PD is associated with impaired brain expression of melatonin and its receptors MT₁ and MT₂. Exogenous melatonin treatment presented an outstanding neuroprotective effect in animal models of PD induced by different toxins, such as 6-hydroxydopamine (6-OHDA), 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), rotenone, paraquat, and maneb. Despite the neuroprotective effects and the improvement of motor impairments, melatonin also presents the potential to improve nonmotor symptoms commonly experienced by PD patients such as sleep and anxiety disorders, depression, and memory dysfunction.

Statin therapy prevents the onset of Parkinson disease in patients with diabetes

OBJECTIVE

We studied the association between the statin dosage and the risk of Parkinson disease (PD) in diabetic patients in Taiwan.

METHODS

One million patients were randomly sampled from a National Health Insurance (NHI) database and followed from 2001 to 2008. Diabetic patients were screened by diagnosis of International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) codes, and statin dosage was determined according to the NHI pharmacy database. PD was diagnosed on the basis of ICD-9-CM codes and anti-Parkinson medication use. Statin users was classified by statin dose-duration-day > 28 and matched with nonusers of statins using a coarsened exact matching method. There were 50,432 patients, and half of them were statin users. We examined the risk of PD between statin users and nonusers of statins and further tested the trends of the relative risk between the statin dosage and PD.

RESULTS

The PD incidence rate was lower in statin users than in nonusers of statins. The crude hazard ratio of PD incidence in statin users was 0.65 (95% confidence interval [CI] = 0.57-0.74) in females and 0.60 (95% CI = 0.51-0.69) in males compared with nonusers of statins. After Cox regression analysis, all statins except lovastatin exerted protective effects on PD incidence and had a significant dose-dependent trend.

INTERPRETATION

In Taiwanese diabetic patients, the risk of PD is lower in statin users than in nonusers of statins. Statin users, except lovastatin users, are dose-dependently associated with a decreased incidence of PD compared with nonusers of statins. This finding provides a new indication for statin beyond lipid control and cardiovascular events in diabetic patients. Ann Neurol 2016;80:532-540.

Human sterol 14α-demethylase as a target for anticancer chemotherapy: towards structure-aided drug design

Rapidly multiplying cancer cells synthesize greater amounts of cholesterol to build their membranes. Cholesterol-lowering drugs (statins) are currently in clinical trials for anticancer chemotherapy. However, given at higher doses, statins cause serious side effects by inhibiting the formation of other biologically important molecules derived from mevalonate. Sterol 14α-demethylase (CYP51), which acts 10 steps downstream, is potentially a more specific drug target because this portion of the pathway is fully committed to cholesterol production. However, screening a variety of commercial and experimental inhibitors of microbial CYP51 orthologs revealed that most of them (including all clinical antifungals) weakly inhibit human CYP51 activity, even if they display high apparent spectral binding affinity. Only one relatively potent compound, (R)-N-(1-(3,4'-difluorobiphenyl-4-yl)-2-(1H-imidazol-1-yl)ethyl)-4-(5-phenyl-1,3,4-oxadiazol-2-yl)benzamide (VFV), was identified. VFV has been further tested in cellular experiments and found to decrease proliferation of different cancer cell types. The crystal structures of human CYP51-VFV complexes (2.0 and 2.5 Å) both display a 2:1 inhibitor/enzyme stoichiometry, provide molecular insights regarding a broader substrate profile, faster catalysis, and weaker susceptibility of human CYP51 to inhibition, and outline directions for the development of more potent inhibitors.

Neutralization of RANTES and Eotaxin Prevents the Loss of Dopaminergic Neurons in a Mouse Model of Parkinson Disease

Parkinson disease (PD) is second only to Alzheimer disease as the most common human neurodegenerative disorder. Despite intense investigation, no interdictive therapy is available for PD. Recent studies indicate that both innate and adaptive immune processes are active in PD. Accordingly, we found a rapid increase in RANTES (regulated on activation normal T cell expressed and secreted) and eotaxin, chemokines that are involved in T cell trafficking, in vivo in the substantia nigra pars compacta and the serum of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-intoxicated mice. RANTES and eotaxin were also up-regulated in the substantia nigra pars compacta of post-mortem PD brains as compared with age-matched controls. Therefore, we investigated whether neutralization of RANTES and eotaxin could protect against nigrostriatal degeneration in MPTP-intoxicated mice. Interestingly, after peripheral administration, functional blocking antibodies against RANTES and eotaxin reduced the infiltration of CD4(+) and CD8(+) T cells into the nigra, attenuated nigral expression of proinflammatory molecules, and suppressed nigral activation of glial cells. These findings paralleled dopaminergic neuronal protection, normalized striatal neurotransmitters, and improved motor functions in MPTP-intoxicated mice. Therefore, we conclude that attenuation of the chemokine-dependent adaptive immune response may be of therapeutic benefit for PD patients.

Succinobucol, a Non-Statin Hypocholesterolemic Drug, Prevents Premotor Symptoms and Nigrostriatal Neurodegeneration in an Experimental Model of Parkinson's Disease

Parkinson's disease (PD) is a neurodegenerative disorder characterized by non-motor and motor disabilities. This study investigated whether succinobucol (SUC) could mitigate nigrostriatal injury caused by intranasal 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) administration in mice. Moreover, the effects of SUC against MPTP-induced behavioral impairments and neurochemical changes were also evaluated. The quantification of tyrosine hydroxylase-positive (TH⁺) cells was also performed in primary mesencephalic cultures to evaluate the effects of SUC against 1-methyl-4-phenylpyridinium (MPP⁺) toxicity in vitro. C57BL/6 mice were treated with SUC (10 mg/kg/day, intragastric (i.g.)) for 30 days, and thereafter, animals received MPTP infusion (1 mg/nostril) and SUC treatment continued for additional 15 days. MPTP-infused animals displayed significant non-motor symptoms including olfactory and short-term memory deficits evaluated in the olfactory discrimination, social recognition, and water maze tasks. These behavioral impairments were accompanied by inhibition of mitochondrial NADH dehydrogenase activity (complex I), as well as significant decrease of TH and dopamine transporter (DAT) immunoreactivity in the substantia nigra pars compacta and striatum. Although SUC treatment did not rescue NADH dehydrogenase activity inhibition, it was able to blunt MPTP-induced behavioral impairments and prevented the decrease in TH and DAT immunoreactivities in substantia nigra (SN) and striatum. SUC also suppressed striatal astroglial activation and increased interleukin-6 levels in MPTP-intoxicated mice. Furthermore, SUC significantly prevented the loss of TH⁺ neurons induced by MPP⁺ in primary mesencephalic cultures. These results provide new evidence that SUC treatment counteracts early non-motor symptoms and neurodegeneration/neuroinflammation in the nigrostriatal pathway induced by intranasal MPTP administration in mice by modulating events downstream to the mitochondrial NADH dehydrogenase inhibition.