Parkinson's Disease Drug Therapies in the Clinical Trial Pipeline: 2022 Update

Prevalence of Late-Stage Parkinson's Disease in the US Healthcare System: Insights from TriNetX

BACKGROUND

Patients in late-stage Parkinson's disease (PDLS) are caregiver-dependent, have low quality of life, and higher healthcare costs.

OBJECTIVE

To estimate the prevalence of PDLS patients in the current US healthcare system.

METHODS

We downloaded the 2010-2022 data from the TriNetX Diamond claims network that consists of 92 US healthcare sites. PD was identified using standard diagnosis codes, and PDLS was identified by the usage of wheelchair dependence, personal care assistance, and/or presence of diagnoses of dementia. Age of PDLS identification and survival information were obtained and stratified by demographic and the disability subgroups.

RESULTS

We identified 1,031,377 PD patients in the TriNetX database. Of these, 18.8% fitted our definition of PDLS (n = 194,297), and 10.2% met two or more late-stage criteria. Among all PDLS, the mean age of PDLS identification was 78.1 (±7.7) years, and 49% were already reported as deceased. PDLS patients were predominantly male (58.5%) with similar distribution across PDLS subgroups. The majority did not have race (71%) or ethnicity (69%) information, but for the available information >90% (n = 53,162) were White, 8.2% (n = 5121) Hispanic/Latino, 7.8% (n = 4557) Black, and <0.01% (n = 408) Asian. Of the PDLS cohort, 71.6% identified with dementia, 12.9% had personal care assistance, and 4.8% were wheelchair-bound.

CONCLUSIONS

Late-stage patients are a significant part of the PD landscape in the current US healthcare system, and largely missed by traditional motor-based disability staging. It is imperative to include this population as a clinical, social, and research priority. © 2024 The Author(s). Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Activation and Purification of ß-Glucocerebrosidase by Exploiting its Transporter LIMP-2 - Implications for Novel Treatment Strategies in Gaucher's and Parkinson's Disease

Genetic variants of GBA1 can cause the lysosomal storage disorder Gaucher disease and are among the highest genetic risk factors for Parkinson's disease (PD). GBA1 encodes the lysosomal enzyme beta-glucocerebrosidase (GCase), which orchestrates the degradation of glucosylceramide (GluCer) in the lysosome. Recent studies have shown that GluCer accelerates α-synuclein aggregation, exposing GCase deficiency as a major risk factor in PD pathology and as a promising target for treatment. This study investigates the interaction of GCase and three disease-associated variants (p.E326K, p.N370S, p.L444P) with their transporter, the lysosomal integral membrane protein 2 (LIMP-2). Overexpression of LIMP-2 in HEK 293T cells boosts lysosomal abundance of wt, E326K, and N370S GCase and increases/rescues enzymatic activity of the wt and E326K variant. Using a novel purification approach, co-purification of untagged wt, E326K, and N370S GCase in complex with His-tagged LIMP-2 from cell supernatant of HEK 293F cells is achieved, confirming functional binding and trafficking for these variants. Furthermore, a single helix in the LIMP-2 ectodomain is exploited to design a lysosome-targeted peptide that enhances lysosomal GCase activity in PD patient-derived and control fibroblasts. These findings reveal LIMP-2 as an allosteric activator of GCase, suggesting a possible therapeutic potential of targeting this interaction.

Developing disease-modifying interventions in idiopathic REM sleep behavior disorder and early synucleinopathy

Alpha-synucleinopathies are prevalent neurological disorders that cause significant disability, leading to progressive clinical deterioration that is currently managed solely through symptomatic treatment. Efforts to evaluate disease-modifying therapies during the established stage of the disease have not yielded positive outcomes in terms of clinical or imaging efficacy endpoints. However, alpha-synucleinopathies have a long prodromal phase that presents a promising opportunity for intervention with disease-modifying therapies. The presence of polysomnography-confirmed REM sleep behavior disorder (RBD) is the most reliable risk factor for identifying individuals in the prodromal stage of alpha-synucleinopathy. This paper discusses the rationale behind targeting idiopathic/isolated RBD in disease-modifying trials and outlines possible study designs, including strategies for patient stratification, selection of biomarkers to assess disease progression and patient eligibility, as well as the identification of suitable endpoints. Additionally, the potential targets for disease-modifying treatment in alpha-synucleinopathies are summarized.

LETC inhibits α-Syn aggregation and ameliorates motor deficiencies in the L62 mouse model of synucleinopathy

Alpha-Synuclein (α-Syn) aggregation is a pathological feature of synucleinopathies, neurodegenerative disorders that include Parkinson's disease (PD). Here, we explored the efficacy of N,N,N',N'-tetraethyl-10H-phenothiazine-3,7-diamine dihydrochloride (LETC), a protein aggregation inhibitor, on α-Syn aggregation. In both cellular models and transgenic mice, α-Syn aggregation was achieved by the overexpression of full-length human α-Syn fused with a signal sequence peptide. α-Syn accumulated in transfected DH60.21 neuroblastoma cells and α-Syn aggregation was inhibited by LETC with an EC50 of 0.066 ± 0.047 μM. Full-length human α-Syn overexpressing Line 62 (L62) mice accumulated neuronal α-Syn that was associated with a decreased motor performance in the open field and automated home cage. LETC, administered orally for 6 weeks at 10 mg/kg significantly decreased α-Syn-positive neurons in multiple brain regions and this resulted in a rescue of movement deficits in the open field in these mice. LETC however, did not improve activity deficits of L62 mice in the home cage environment. The results suggest that LETC may provide a potential disease modification therapy in synucleinopathies through the inhibition of α-Syn aggregation.

New Advances in the Pharmacology and Toxicology of Lithium: A Neurobiologically Oriented Overview

Over the last six decades, lithium has been considered the gold standard treatment for the long-term management of bipolar disorder due to its efficacy in preventing both manic and depressive episodes as well as suicidal behaviors. Nevertheless, despite numerous observed effects on various cellular pathways and biologic systems, the precise mechanism through which lithium stabilizes mood remains elusive. Furthermore, there is recent support for the therapeutic potential of lithium in other brain diseases. This review offers a comprehensive examination of contemporary understanding and predominant theories concerning the diverse mechanisms underlying lithium's effects. These findings are based on investigations utilizing cellular and animal models of neurodegenerative and psychiatric disorders. Recent studies have provided additional support for the significance of glycogen synthase kinase-3 (GSK3) inhibition as a crucial mechanism. Furthermore, research has shed more light on the interconnections between GSK3-mediated neuroprotective, antioxidant, and neuroplasticity processes. Moreover, recent advancements in animal and human models have provided valuable insights into how lithium-induced modifications at the homeostatic synaptic plasticity level may play a pivotal role in its clinical effectiveness. We focused on findings from translational studies suggesting that lithium may interface with microRNA expression. Finally, we are exploring the repurposing potential of lithium beyond bipolar disorder. These recent findings on the therapeutic mechanisms of lithium have provided important clues toward developing predictive models of response to lithium treatment and identifying new biologic targets. SIGNIFICANCE STATEMENT: Lithium is the drug of choice for the treatment of bipolar disorder, but its mechanism of action in stabilizing mood remains elusive. This review presents the latest evidence on lithium's various mechanisms of action. Recent evidence has strengthened glycogen synthase kinase-3 (GSK3) inhibition, changes at the level of homeostatic synaptic plasticity, and regulation of microRNA expression as key mechanisms, providing an intriguing perspective that may help bridge the mechanistic gap between molecular functions and its clinical efficacy as a mood stabilizer.

Discovery of potent inhibitors of α-synuclein aggregation using structure-based iterative learning

Machine learning methods hold the promise to reduce the costs and the failure rates of conventional drug discovery pipelines. This issue is especially pressing for neurodegenerative diseases, where the development of disease-modifying drugs has been particularly challenging. To address this problem, we describe here a machine learning approach to identify small molecule inhibitors of α-synuclein aggregation, a process implicated in Parkinson's disease and other synucleinopathies. Because the proliferation of α-synuclein aggregates takes place through autocatalytic secondary nucleation, we aim to identify compounds that bind the catalytic sites on the surface of the aggregates. To achieve this goal, we use structure-based machine learning in an iterative manner to first identify and then progressively optimize secondary nucleation inhibitors. Our results demonstrate that this approach leads to the facile identification of compounds two orders of magnitude more potent than previously reported ones.

Targeting Mitochondrial Complex I Deficiency in MPP+/MPTP-induced Parkinson's Disease Cell Culture and Mouse Models by Transducing Yeast NDI1 Gene

BACKGROUND

MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine), original found in synthetic heroin, causes Parkinson's disease (PD) in human through its metabolite MPP+ by inhibiting complex I of mitochondrial respiratory chain in dopaminergic neurons. This study explored whether yeast internal NADH-quinone oxidoreductase (NDI1) has therapeutic effects in MPTP- induced PD models by functionally compensating for the impaired complex I. MPP+-treated SH-SY5Y cells and MPTP-treated mice were used as the PD cell culture and mouse models respectively. The recombinant NDI1 lentivirus was transduced into SH-SY5Y cells, or the recombinant NDI1 adeno-associated virus (rAAV5-NDI1) was injected into substantia nigra pars compacta (SNpc) of mice.

RESULTS

The study in vitro showed NDI1 prevented MPP+-induced change in cell morphology and decreased cell viability, mitochondrial coupling efficiency, complex I-dependent oxygen consumption, and mitochondria-derived ATP. The study in vivo revealed that rAAV-NDI1 injection significantly improved the motor ability and exploration behavior of MPTP-induced PD mice. Accordingly, NDI1 notably improved dopaminergic neuron survival, reduced the inflammatory response, and significantly increased the dopamine content in striatum and complex I activity in substantia nigra.

CONCLUSIONS

NDI1 compensates for the defective complex I in MPP+/MPTP-induced models, and vastly alleviates MPTP-induced toxic effect on dopaminergic neurons. Our study may provide a basis for gene therapy of sporadic PD with defective complex I caused by MPTP-like substance.

Trial of Lixisenatide in Early Parkinson's Disease

BACKGROUND

Lixisenatide, a glucagon-like peptide-1 receptor agonist used for the treatment of diabetes, has shown neuroprotective properties in a mouse model of Parkinson's disease.

METHODS

In this phase 2, double-blind, randomized, placebo-controlled trial, we assessed the effect of lixisenatide on the progression of motor disability in persons with Parkinson's disease. Participants in whom Parkinson's disease was diagnosed less than 3 years earlier, who were receiving a stable dose of medications to treat symptoms, and who did not have motor complications were randomly assigned in a 1:1 ratio to daily subcutaneous lixisenatide or placebo for 12 months, followed by a 2-month washout period. The primary end point was the change from baseline in scores on the Movement Disorder Society-Unified Parkinson's Disease Rating Scale (MDS-UPDRS) part III (range, 0 to 132, with higher scores indicating greater motor disability), which was assessed in patients in the on-medication state at 12 months. Secondary end points included other MDS-UPDRS subscores at 6, 12, and 14 months and doses of levodopa equivalent.

RESULTS

A total of 156 persons were enrolled, with 78 assigned to each group. MDS-UPDRS part III scores at baseline were approximately 15 in both groups. At 12 months, scores on the MDS-UPDRS part III had changed by -0.04 points (indicating improvement) in the lixisenatide group and 3.04 points (indicating worsening disability) in the placebo group (difference, 3.08; 95% confidence interval, 0.86 to 5.30; P = 0.007). At 14 months, after a 2-month washout period, the mean MDS-UPDRS motor scores in the off-medication state were 17.7 (95% CI, 15.7 to 19.7) with lixisenatide and 20.6 (95% CI, 18.5 to 22.8) with placebo. Other results relative to the secondary end points did not differ substantially between the groups. Nausea occurred in 46% of participants receiving lixisenatide, and vomiting occurred in 13%.

CONCLUSIONS

In participants with early Parkinson's disease, lixisenatide therapy resulted in less progression of motor disability than placebo at 12 months in a phase 2 trial but was associated with gastrointestinal side effects. Longer and larger trials are needed to determine the effects and safety of lixisenatide in persons with Parkinson's disease. (Funded by the French Ministry of Health and others; LIXIPARK ClinicalTrials.gov number, NCT03439943.).

HER-096 is a CDNF-derived brain-penetrating peptidomimetic that protects dopaminergic neurons in a mouse synucleinopathy model of Parkinson's disease

Cerebral dopamine neurotrophic factor (CDNF) is an unconventional neurotropic factor that modulates unfolded protein response (UPR) pathway signaling and alleviates endoplasmic reticulum (ER) stress providing cytoprotective effects in different models of neurodegenerative disorders. Here, we developed a brain-penetrating peptidomimetic compound based on human CDNF. This compound called HER-096 shows similar potency and mechanism of action as CDNF, and promotes dopamine neuron survival, reduces α-synuclein aggregation and modulates UPR signaling in in vitro models. HER-096 is metabolically stable and able to penetrate to cerebrospinal (CSF) and brain interstitial fluids (ISF) after subcutaneous administration, with an extended CSF and brain ISF half-life compared to plasma. Subcutaneously administered HER-096 modulated UPR pathway activity, protected dopamine neurons, and reduced α-synuclein aggregates and neuroinflammation in substantia nigra of aged mice with synucleinopathy. Peptidomimetic HER-096 is a candidate for development of a disease-modifying therapy for Parkinson's disease with a patient-friendly route of administration.

Lewy body dementia: Overcoming barriers and identifying solutions

Despite its high prevalence among dementias, Lewy body dementia (LBD) remains poorly understood with a limited, albeit growing, evidence base. The public-health burden that LBD imposes is worsened by overlapping pathologies, which contribute to misdiagnosis, and lack of treatments. For this report, we gathered and analyzed public-domain information on advocacy, funding, research outputs, and the therapeutic pipeline to identify gaps in each of these key elements. To further understand the current gaps, we also conducted interviews with leading experts in regulatory/governmental agencies, LBD advocacy, academic research, and biopharmaceutical research, as well as with funding sources. We identified wide gaps across the entire landscape, the most critical being in research. Many of the experts participated in a workshop to discuss the prioritization of research areas with a view to accelerating therapeutic development and improving patient care. This white paper outlines the opportunities for bridging the major LBD gaps and creates the framework for collaboration in that endeavor. HIGHLIGHTS: A group representing academia, government, industry, and consulting expertise was convened to discuss current progress in Dementia with Lewy Body care and research. Consideration of expert opinion,natural language processing of the literature as well as publicly available data bases, and Delphi inspired discussion led to a proposed consensus document of priorities for the field.

Distinct tau and alpha-synuclein molecular signatures in Alzheimer's disease with and without Lewy bodies and Parkinson's disease with dementia

Alpha-synuclein (aSyn) pathology is present in approximately 50% of Alzheimer's disease (AD) cases at autopsy and might impact the age-of-onset and disease progression in AD. Here, we aimed to determine whether tau and aSyn profiles differ between AD cases with Lewy bodies (AD-LB), pure AD and Parkinson's disease with dementia (PDD) cases using epitope-, post-translational modification- (PTM) and isoform-specific tau and aSyn antibody panels spanning from the N- to C-terminus. We included the middle temporal gyrus (MTG) and amygdala (AMY) of clinically diagnosed and pathologically confirmed cases and performed dot blotting, western blotting and immunohistochemistry combined with quantitative and morphological analyses. All investigated phospho-tau (pTau) species, except pT181, were upregulated in AD-LB and AD cases compared to PDD and control cases, but no significant differences were observed between AD-LB and AD subjects. In addition, tau antibodies targeting the proline-rich regions and C-terminus showed preferential binding to AD-LB and AD brain homogenates. Antibodies targeting C-terminal aSyn epitopes and pS129 aSyn showed stronger binding to AD-LB and PDD cases compared to AD and control cases. Two pTau species (pS198 and pS396) were specifically detected in the soluble protein fractions of AD-LB and AD subjects, indicative of early involvement of these PTMs in the multimerization process of tau. Other phospho-variants for both tau (pT212/S214, pT231 and pS422) and aSyn (pS129) were only detected in the insoluble protein fraction of AD-LB/AD and AD-LB/PDD cases, respectively. aSyn load was higher in the AMY of AD-LB cases compared to PDD cases, suggesting aggravated aSyn pathology under the presence of AD pathology, while tau load was similar between AD-LB and AD cases. Co-localization of pTau and aSyn could be observed within astrocytes of AD-LB cases within the MTG. These findings highlight a unique pathological signature for AD-LB cases compared to pure AD and PDD cases.

Blood-brain Barrier and Neurovascular Unit Dysfunction in Parkinson's Disease: From Clinical Insights to Pathogenic Mechanisms and Novel Therapeutic Approaches

The blood-brain barrier (BBB) plays a crucial role in the central nervous system by tightly regulating the influx and efflux of biological substances between the brain parenchyma and peripheral circulation. Its restrictive nature acts as an obstacle to protect the brain from potentially noxious substances such as blood-borne toxins, immune cells, and pathogens. Thus, the maintenance of its structural and functional integrity is vital in the preservation of neuronal function and cellular homeostasis in the brain microenvironment. However, the barrier's foundation can become compromised during neurological or pathological conditions, which can result in dysregulated ionic homeostasis, impaired transport of nutrients, and accumulation of neurotoxins that eventually lead to irreversible neuronal loss. Initially, the BBB is thought to remain intact during neurodegenerative diseases, but accumulating evidence as of late has suggested the possible association of BBB dysfunction with Parkinson's disease (PD) pathology. The neurodegeneration occurring in PD is believed to stem from a myriad of pathogenic mechanisms, including tight junction alterations, abnormal angiogenesis, and dysfunctional BBB transporter mechanism, which ultimately causes altered BBB permeability. In this review, the major elements of the neurovascular unit (NVU) comprising the BBB are discussed, along with their role in the maintenance of barrier integrity and PD pathogenesis. We also elaborated on how the neuroendocrine system can influence the regulation of BBB function and PD pathogenesis. Several novel therapeutic approaches targeting the NVU components are explored to provide a fresh outlook on treatment options for PD.

Dietary Interventions in Parkinson's Disease

Several dietary patterns and nutritional supplements have been linked to the development, progression, and symptomatic treatment of Parkinson's disease (PD). Most of the evidence, at this point, is preliminary and based largely on observational studies. Interventional studies are scarce, so the evidence on effectiveness remains inconclusive. Dietary interventions could, analogous to exercise, potentially have a beneficial effect on disease symptoms as well as on the progression of the disease and should therefore be researched in high quality studies. Further work is also needed to study whether dietary interventions, when applied to an at-risk population, have any potential to postpone the onset of manifest PD. In this paper, we summarize all ongoing clinical trials on dietary interventions in PD. We found 10 ongoing studies, all aimed at a different intervention. These studies are mostly exploratory in nature or represent phase I or phase II trials focusing on safety, biological responses, and symptomatic effects. Taken together, we conclude that research on dietary interventions in persons with PD is still in its early days. The results of the various ongoing trials are expected to generate new hypotheses and will help to shape the agenda for future research on this important topic.

Multiplexed Digital Characterization of Misfolded Protein Oligomers via Solid-State Nanopores

Misfolded protein oligomers are of central importance in both the diagnosis and treatment of Alzheimer's and Parkinson's diseases. However, accurate high-throughput methods to detect and quantify oligomer populations are still needed. We present here a single-molecule approach for the detection and quantification of oligomeric species. The approach is based on the use of solid-state nanopores and multiplexed DNA barcoding to identify and characterize oligomers from multiple samples. We study α-synuclein oligomers in the presence of several small-molecule inhibitors of α-synuclein aggregation as an illustration of the potential applicability of this method to the development of diagnostic and therapeutic methods for Parkinson's disease.

Biotin rescues manganese-induced Parkinson's disease phenotypes and neurotoxicity

Occupational exposure to manganese (Mn) induces manganism and has been widely linked as a contributing environmental factor to Parkinson's disease (PD), featuring dramatic signature overlaps between the two in motor symptoms and clinical hallmarks. However, the molecular mechanism underlying such link remains elusive, and for combating PD, effective mechanism-based therapies are lacking. Here, we developed an adult Drosophila model of Mn toxicity to recapitulate key parkinsonian features, spanning behavioral deficits, neuronal loss, and dysfunctions in lysosome and mitochondria. We performed global metabolomics on flies at an early stage of toxicity and identified metabolism of the B vitamin, biotin (vitamin B 7 ), as a master pathway underpinning Mn toxicity with systemic, body-brain increases in Mn-treated groups compared to the controls. Using Btnd RNAi mutant flies, we show that biotin depletion exacerbates Mn-induced neurotoxicity, parkinsonism, and mitochondrial dysfunction; while in Mn-exposed wild-type flies, biotin feeding dramatically ameliorates these pathophenotypes. We further show in human induced stem cells (iPSCs)- differentiated midbrain dopaminergic neurons that the supplemented biotin protects against Mn-induced neuronal loss, cytotoxicity, and mitochondrial dysregulation. Finally, human data profiling biotin-related proteins show for PD cases elevated circulating levels of biotin transporters but not of metabolic enzymes compared to healthy controls, suggesting humoral biotin transport as a key event involved in PD. Taken together, our findings identified compensatory biotin pathway as a convergent, systemic driver of Mn toxicity and parkinsonian pathology, providing new basis for devising effective countermeasures against manganism and PD.

Significance Statement

Environmental exposure to manganese (Mn) may increase the risk for Parkinson's disease (PD); however, the mechanistic basis linking the two remains unclear. Our adult fruit fly ( Drosophila ) model of Mn toxicity recapitulated key Parkinson's hallmarks in vivo spanning behavioral deficits, neuronal loss, and mitochondrial dysfunction. Metabolomics identified the biotin (vitamin B 7 ) pathway as a key mediator, featuring systemic biotin increases in the flies. Rescue trials leveraging biotin-deficient flies, wild-type flies, and human iPSC-derived dopaminergic neurons determined biotin as a driver of manganism, with the parkinsonian phenotypes dramatically reversed through biotin supplementation. Our findings, in line with overexpressed circulating biotin transporters observed in PD patients, suggest compensatory biotin pathway as a key to untangle the Mn-PD link for combating neurodegenerative disease.

Extracellular vesicles released by hair follicle and adipose mesenchymal stromal cells induce comparable neuroprotective and anti-inflammatory effects in primary neuronal and microglial cultures

BACKGROUND AIMS

Despite intensive research, to date, there is no effective treatment for neurodegenerative diseases. Among the different therapeutic approaches, recently, the use of extracellular vesicles (EVs) derived from mesenchymal stromal cells (MSCs) has gained attention.

METHODS

In the present work, we focused on medium/large extracellular vesicles (m/lEVs) derived from hair follicle--derived (HF) MSCs, comparing their potential neuroprotective and anti-inflammatory effect against adipose tissue (AT)-MSC-derived m/lEVs.

RESULTS

The obtained m/lEVs were similar in size with comparable expression of surface protein markers. The neuroprotective effect of both HF-m/lEVs and AT-m/lEVs was statistically significant in dopaminergic primary cell cultures, increasing cell viability after the incubation with 6-hidroxydopamine neurotoxin. Moreover, the administration of HF-m/lEVs and AT-m/lEVs counteracted the lipopolysaccharide-induced inflammation in primary microglial cell cultures, decreasing the levels of pro-inflammatory cytokines, tumor necrosis factor-α and interleukin-1β.

CONCLUSIONS

Taken together, HF-m/lEVs demonstrated comparable potential with that of AT-m/lEVs as multifaceted biopharmaceuticals for neurodegenerative disease treatment.

Multi-pinhole collimator design in different numbers of projections for brain SPECT

Purpose

High resolution and sensitivity brain SPECT is promising for the accurate diagnosis of Alzheimer's disease (AD) and Parkinson's disease (PD). Multi-pinhole (MPH) collimators with a good performance in imaging small field-of-view (FOV) could be better used for brain SPECT. In this study, we aim to evaluate the impact of varying the number of pinholes and the number of projections on the performance of MPH brain SPECT.

Methods

The system design was based on a commercial clinical dual-head SPECT/CT scanner, with target spatial resolutions of 12 mm and 8 mm for AD and PD SPECT, respectively. In total, 1-25 pinholes were modeled for 64, 32, 16, 8, 4, and 2 projections. The 3D NURBS-based HUman Brain (NHUB) phantom was used in the analytical simulation to model 99mTc-HMPAO and 99mTc-TRODAT distributions. The 2D Derenzo hot-rod phantom and star phantom were used in Monte Carlo simulations to evaluate the spatial resolution and angular sampling performance of MPH. The influence of different detector positions was also evaluated for 2, 4, and 6 angular views. The projections were reconstructed using the 3D MPH ML-EM method. Normalized mean square error, coefficient of variation, and image profiles were evaluated.

Results

Along with the decrease in the number of projections, more pinholes are required to achieve the optimum performance. For 32 projections, 9- and 7-pinhole collimators provide the best normalized mean square error (NMSE) to the coefficient of variation (COV) trade-off for 99mTc-HMPAO and 99mTc-TRODAT, respectively. Detector positions substantially affect the image quality for MPH SPECT for 2 and 4 angular views. The smallest rod size for the Derenzo hot-rod phantom, which could be resolved, is 7.9 mm for the MPH general purpose collimator (MPGP) with more than 16 projections and 6.4 mm for MPH high-resolution collimator (MPHR) with more than 8 projections.

Conclusion

The number of pinholes affects the performance of the MPH collimator, especially when the projection views become fewer. More pinholes are required for fewer projections to provide better angular sampling in MPH for complex activity distributions. Detector positions affect the image quality of MPH SPECT for 2 and 4 angular views, where L-mode acquisition is slightly superior to H-mode. MPH collimators exhibited improved spatial resolution and angular sampling compared with both LEHR and single pinhole collimators.

Secondary Processes Dominate the Quiescent, Spontaneous Aggregation of α-Synuclein at Physiological pH with Sodium Salts

The accurate recapitulation in an in vitro assay of the aggregation process of α-synuclein in Parkinson's disease has been a significant challenge. As α-synuclein does not aggregate spontaneously in most currently used in vitro assays, primary nucleation is triggered by the presence of surfaces such as lipid membranes or interfaces created by shaking, to achieve aggregation on accessible time scales. In addition, secondary nucleation is typically only observed by lowering the pH below 5.8. Here we investigated assay conditions that enables spontaneous primary nucleation and secondary nucleation at pH 7.4. Using 400 mM sodium phosphate, we observed quiescent spontaneous aggregation of α-synuclein and established that this aggregation is dominated by secondary processes. Furthermore, the presence of potassium ions enhanced the reproducibility of quiescent α-synuclein aggregation. This work provides a framework for the study of spontaneous α-synuclein aggregation at physiological pH.

Protein aggregation and neurodegenerative disease: Structural outlook for the novel therapeutics

Before the controversial approval of humanized monoclonal antibody lecanemab, which binds to the soluble amyloid-β protofibrils, all the treatments available earlier, for Alzheimer's disease (AD) were symptomatic. The researchers are still struggling to find a breakthrough in AD therapeutic medicine, which is partially attributable to lack in understanding of the structural information associated with the intrinsically disordered proteins and amyloids. One of the major challenges in this area of research is to understand the structural diversity of intrinsically disordered proteins under in vitro conditions. Therefore, in this review, we have summarized the in vitro applications of biophysical methods, which are aimed to shed some light on the heterogeneity, pathogenicity, structures and mechanisms of the intrinsically disordered protein aggregates associated with proteinopathies including AD. This review will also rationalize some of the strategies in modulating disease-relevant pathogenic protein entities by small molecules using structural biology approaches and biophysical characterization. We have also highlighted tools and techniques to simulate the in vivo conditions for native and cytotoxic tau/amyloids assemblies, urge new chemical approaches to replicate tau/amyloids assemblies similar to those in vivo conditions, in addition to designing novel potential drugs.

Parkinson's Disease Drug Therapies in the Clinical Trial Pipeline: 2023 Update

BACKGROUND

Since 2020, annual reports on the clinical development of new drug-based therapies for the neurodegenerative condition of Parkinson's disease (PD) have been generated. These reviews have followed the progress of both "symptomatic treatments" (ST - improves/reduces symptoms of the condition) and "disease modifying treatments" (DMT - attempts to delay/slow progression by addressing the underlying biology of PD). Additional efforts have been made to further categorize these experimental treatments based on their mechanisms of action and class of drug.

METHODS

A dataset of clinical trials for drug therapies in PD was obtained using trial data downloaded from the ClinicalTrials.gov online registry. A breakdown analysis of all the studies that were active as of January 31st, 2023, was conducted.

RESULTS

There was a total of 139 clinical trials registered on the ClinicalTrials.gov website as active (with 35 trials newly registered since our last report). Of these trials, 76 (55%) were considered ST and 63 (45%) were designated DMT. Similar to previous years, approximately a third of the studies were in Phase 1 (n = 47; 34%), half (n = 72, 52%) were in Phase 2 and there were 20 (14%) studies in Phase 3. Novel therapies again represented the most dominant group of experimental treatments in this year's report with 58 (42%) trials testing new agents. Repurposed drugs are present in a third (n = 49, 35%) of trials, with reformulations and new claims representing 19% and 4% of studies, respectively.

CONCLUSIONS

Our fourth annual review of active clinical trials evaluating ST and DMT therapeutics for PD demonstrates that the drug development pipeline is dynamic and evolving. The slow progress and lack of agents transitioning from Phase 2 to Phase 3 is concerning, but collective efforts by various stakeholders are being made to accelerate the clinical trial process, with the aim of bringing new therapies to the PD community sooner.

Clinical benefit of MAO-B and COMT inhibition in Parkinson's disease: practical considerations

Inhibitors of monoamine oxidase B (MAO-B) and catechol-O-methyltransferase (COMT) are major strategies to reduce levodopa degradation and thus to increase and prolong its effect in striatal dopaminergic neurotransmission in Parkinson's disease patients. While selegiline/rasagiline and tolcapone/entacapone have been available on the market for more than one decade, safinamide and opicapone have been approved in 2015 and 2016, respectively. Meanwhile, comprehensive data from several post-authorization studies have described the use and specific characteristics of the individual substances in clinical practice under real-life conditions. Here, we summarize current knowledge on both medication classes, with a focus on the added clinical value in Parkinson's disease. Furthermore, we outline practical considerations in the treatment of motor fluctuations and provide an outlook on ongoing studies with MAO-B and COMT inhibitors.

Dementia with Lewy Bodies Drug Therapies in Clinical Trials: Systematic Review up to 2022

INTRODUCTION

Reviews of randomized clinical trials (RCTs) in dementia with Lewy bodies (DLB) are essential for informing ongoing research efforts of symptomatic therapies and potentially disease-modifying therapies (DMTs).

METHODS

We performed a systematic review of all clinical trials conducted until September 27, 2022, by examining 3 international registries: ClinicalTrials.gov, the European Union Drug Regulating Authorities Clinical Trials Database, and the International Clinical Trials Registry Platform, to identify drugs in trials in DLB.

RESULTS

We found 25 agents in 40 trials assessing symptomatic treatments and DMTs for DLB: 7 phase 3, 31 phase 2, and 2 phase 1 trials. We found an active pipeline for drug development in DLB, with most ongoing clinical trials in phase 2. We identified a recent trend towards including participants at the prodromal stages, although more than half of active clinical trials will enroll mild to moderate dementia patients. Additionally, repurposed agents are frequently tested, representing 65% of clinical trials.

CONCLUSION

Current challenges in DLB clinical trials include the need for disease-specific outcome measures and biomarkers, and improving representation of global and diverse populations.

Parkinson's disease therapy: what lies ahead?

The worldwide prevalence of Parkinson's disease (PD) has been constantly increasing in the last decades. With rising life expectancy, a longer disease duration in PD patients is observed, further increasing the need and socioeconomic importance of adequate PD treatment. Today, PD is exclusively treated symptomatically, mainly by dopaminergic stimulation, while efforts to modify disease progression could not yet be translated to the clinics. New formulations of approved drugs and treatment options of motor fluctuations in advanced stages accompanied by telehealth monitoring have improved PD patients care. In addition, continuous improvement in the understanding of PD disease mechanisms resulted in the identification of new pharmacological targets. Applying novel trial designs, targeting of pre-symptomatic disease stages, and the acknowledgment of PD heterogeneity raise hopes to overcome past failures in the development of drugs for disease modification. In this review, we address these recent developments and venture a glimpse into the future of PD therapy in the years to come.

The heterogeneity of Parkinson's disease

The heterogeneity of Parkinson's disease (PD), i.e. the various clinical phenotypes, pathological findings, genetic predispositions and probably also the various implicated pathophysiological pathways pose a major challenge for future research projects and therapeutic trail design. We outline several pathophysiological concepts, pathways and mechanisms, including the presumed roles of α-synuclein misfolding and aggregation, Lewy bodies, oxidative stress, iron and melanin, deficient autophagy processes, insulin and incretin signaling, T-cell autoimmunity, the gut-brain axis and the evidence that microbial (viral) agents may induce molecular hallmarks of neurodegeneration. The hypothesis is discussed, whether PD might indeed be triggered by exogenous (infectious) agents in susceptible individuals upon entry via the olfactory bulb (brain first) or the gut (body-first), which would support the idea that disease mechanisms may change over time. The unresolved heterogeneity of PD may have contributed to the failure of past clinical trials, which attempted to slow the course of PD. We thus conclude that PD patients need personalized therapeutic approaches tailored to specific phenomenological and etiologic subtypes of disease.

Parkinson's disease - current treatment

PURPOSE OF REVIEW

The purpose is to review the results and impact of recent studies for current and future treatment of both motor and non-motor symptoms in Parkinson's disease (PD).

RECENT FINDINGS

New formulations of levodopa further optimize motor fluctuations, allowing for more on-time and less dyskinesia. On demand apomorphine continues to showcase itself as an effective and tolerable tool for treating motor off-periods. Though there are no clear treatment guidelines for PD-related constipation and sleep related disorders, several new agents for these non-motor symptoms show promising preliminary data. Expiratory muscle strength training may represent a useful and cost-effective strategy to alleviate oropharyngeal dysphagia associated with PD. There is evidence to suggest that the use of shorter pulse width and directional deep brain stimulation leads can results in a greater therapeutic window.

SUMMARY

Though no interventions currently exist to significantly modify the disease progression of PD, new studies continue to give insight into optimal symptomatic management. Clinicians should be familiar with expanding the repertoire of tools available to treat the diverse range of symptoms and challenges associated with PD.

GM1 Ganglioside as a Disease-Modifying Therapeutic for Parkinson's Disease: A Multi-Functional Glycosphingolipid That Targets Multiple Parkinson's Disease-Relevant Pathogenic Mechanisms

Parkinson's disease (PD) is a progressive neurodegenerative disorder affecting millions of patients worldwide. Many therapeutics are available for treating PD symptoms but there is no disease-modifying therapeutic that has been unequivocally shown to slow or stop the progression of the disease. There are several factors contributing to the failure of many putative disease-modifying agents in clinical trials and these include the choice of patients and clinical trial designs for disease modification trials. Perhaps more important, however, is the choice of therapeutic, which for the most part, has not taken into account the multiple and complex pathogenic mechanisms and processes involved in PD. This paper discusses some of the factors contributing to the lack of success in PD disease-modification trials, which have mostly investigated therapeutics with a singular mechanism of action directed at one of the many PD pathogenic processes, and suggests that an alternative strategy for success may be to employ multi-functional therapeutics that target multiple PD-relevant pathogenic mechanisms. Evidence is presented that the multi-functional glycosphingolipid GM1 ganglioside may be just such a therapeutic.

Cannabidiol Protects Dopaminergic-like Neurons against Paraquat- and Maneb-Induced Cell Death through Safeguarding DJ-1CYS106 and Caspase 3 Independently of Cannabinoid Receptors: Relevance in Parkinson's Disease

Parkinson's disease (PD), a progressive neurodegenerative movement disorder, has reached pandemic status worldwide. This neurologic disorder is caused primarily by the specific deterioration of dopaminergic (DAergic) neurons in the substantia nigra pars compacta (SNc). Unfortunately, there are no therapeutic agents that slow or delay the disease progression. Herein, menstrual stromal cell-derived dopamine-like neurons (DALNs) intoxicated with paraquat (PQ²⁺)/maneb (MB) were used as a model system to elucidate the mechanism by which CBD protects the neural cell from apoptosis in vitro. According to immunofluorescence microscopy, flow cytometry, cell-free assay, and molecular docking analysis, we demonstrate that CBD offers protection to DALNs against PQ²⁺ (1 mM)/MB (50 μM)-induced oxidative stress (OS) by simultaneously (i) decreasing reactive oxygen species (ROS: O₂^•-, H₂O₂), (ii) maintaining the mitochondrial membrane potential (ΔΨ_m), (iii) directly binding to stress sensor protein DJ-1, thereby blunting its oxidation from DJ-1CYS¹⁰⁶-SH into DJ-1CYS¹⁰⁶-SO₃, and (iv) directly binding to pro-apoptotic protease protein caspase 3 (CASP3), thereby disengaging neuronal dismantling. Furthermore, the protective effect of CBD on DJ-1 and CASP3 was independent of CB1 and CB2 receptor signaling. CBD also re-established the Ca²⁺ influx in DALNs as a response to dopamine (DA) stimuli under PQ²⁺/MB exposure. Because of its powerful antioxidant and antiapoptotic effects, CBD offers potential therapeutic utility in the treatment of PD.

Development and early qualitative evidence of two novel patient-reported outcome instruments to assess daily functioning in people with early-stage Parkinson's

BACKGROUND

Previous research on concepts that are important to people living with early-stage Parkinson's indicated that 'functional' slowness, fine motor skills, and subtle gait abnormalities are cardinal concepts that are not comprehensively captured by existing patient-reported outcome (PRO) instruments that are used in clinical practice and research to assess symptoms and daily functioning within this patient population. We sought to develop novel PRO instruments to address this unmet need.

METHODS

PRO instrument development was led by a multidisciplinary research group, including people living with Parkinson's (termed 'patient experts'), as well as patient engagement and involvement, regulatory science, clinical, and outcome measurement experts. A first set of PRO instruments, termed Early Parkinson's Function Slowness (42 items) and Early Parkinson's Mobility (26 items), were drafted to capture 'functional' slowness, fine motor skills, and subtle gait abnormalities. These PRO instruments were used in cognitive debriefing interviews with people living with early-stage Parkinson's (who were not involved with the multidisciplinary research group) to identify issues with relevance, clarity, ease of completion, conceptual overlap, or missing concepts.

RESULTS

Sixty people living with early-stage Parkinson's were interviewed, which led to refining the items to 45 for the Early Parkinson's Functional Slowness and 23 for the Early Parkinson's Mobility PRO instruments. Refinement included rewording items to address clarity issues, merging or splitting items to address overlap issues, and adding new items to address missing concepts. The Early Parkinson's Function Slowness PRO instrument resulted in a multidimensional instrument covering upper limb, complex/whole body, general activity, and cognitive functional slowness. The Early Parkinson's Mobility PRO instrument resulted in comprehensive coverage of everyday mobility tasks, with a focus on gait concepts, plus complex/whole body, balance, and lower limb mobility.

CONCLUSIONS

The Early Parkinson's Function Slowness and Early Parkinson's Mobility PRO instruments aim to address gaps in existing PRO instruments to measure meaningful symptoms and daily functioning in people living with early-stage Parkinson's. Utilizing a meticulous study design led by a multidisciplinary research group that included patient experts helped to ensure that the PRO instruments were patient-centric, content valid, and meaningful from a clinical and measurement perspective.

Evaluation of a Structured Screening Assessment to Detect Isolated Rapid Eye Movement Sleep Behavior Disorder

BACKGROUND

Isolated rapid eye movement (REM) sleep behavior disorder (iRBD) cohorts have provided insights into the earliest neurodegenerative processes in α-synucleinopathies. Even though polysomnography (PSG) remains the gold standard for diagnosis, an accurate questionnaire-based algorithm to identify eligible subjects could facilitate efficient recruitment in research.

OBJECTIVE

This study aimed to optimize the identification of subjects with iRBD from the general population.

METHODS

Between June 2020 and July 2021, we placed newspaper advertisements, including the single-question screen for RBD (RBD1Q). Participants' evaluations included a structured telephone screening consisting of the RBD screening questionnaire (RBDSQ) and additional sleep-related questionnaires. We examined anamnestic information predicting PSG-proven iRBD using logistic regressions and receiver operating characteristic curves.

RESULTS

Five hundred forty-three participants answered the advertisements, and 185 subjects fulfilling inclusion and exclusion criteria were screened. Of these, 124 received PSG after expert selection, and 78 (62.9%) were diagnosed with iRBD. Selected items of the RBDSQ, the Pittsburgh Sleep Quality Index, the STOP-Bang questionnaire, and age predicted iRBD with high accuracy in a multiple logistic regression model (area under the curve >80%). When comparing the algorithm to the sleep expert decision, 77 instead of 124 polysomnographies (62.1%) would have been carried out, and 63 (80.8%) iRBD patients would have been identified; 32 of 46 (69.6%) unnecessary PSG examinations could have been avoided.

CONCLUSIONS

Our proposed algorithm displayed high diagnostic accuracy for PSG-proven iRBD cost-effectively and may be a convenient tool for research and clinical settings. External validation sets are warranted to prove reliability. © 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Sigma-2 Receptors—From Basic Biology to Therapeutic Target: A Focus on Age-Related Degenerative Diseases

There is a large unmet medical need to develop disease-modifying treatment options for individuals with age-related degenerative diseases of the central nervous system. The sigma-2 receptor (S2R), encoded by TMEM97, is expressed in brain and retinal cells, and regulates cell functions via its co-receptor progesterone receptor membrane component 1 (PGRMC1), and through other protein–protein interactions. Studies describing functions of S2R involve the manipulation of expression or pharmacological modulation using exogenous small-molecule ligands. These studies demonstrate that S2R modulates key pathways involved in age-related diseases including autophagy, trafficking, oxidative stress, and amyloid-β and α-synuclein toxicity. Furthermore, S2R modulation can ameliorate functional deficits in cell-based and animal models of disease. This review summarizes the current evidence-based understanding of S2R biology and function, and its potential as a therapeutic target for age-related degenerative diseases of the central nervous system, including Alzheimer’s disease, α-synucleinopathies, and dry age-related macular degeneration.

Exploration and Exploitation Approaches Based on Generative Machine Learning to Identify Potent Small Molecule Inhibitors of α-Synuclein Secondary Nucleation

The high attrition rate in drug discovery pipelines is an especially pressing issue for Parkinson's disease, for which no disease-modifying drugs have yet been approved. Numerous clinical trials targeting α-synuclein aggregation have failed, at least in part due to the challenges in identifying potent compounds in preclinical investigations. To address this problem, we present a machine learning approach that combines generative modeling and reinforcement learning to identify small molecules that perturb the kinetics of aggregation in a manner that reduces the production of oligomeric species. Training data were obtained by an assay reporting on the degree of inhibition of secondary nucleation, which is the most important mechanism of α-synuclein oligomer production. This approach resulted in the identification of small molecules with high potency against secondary nucleation.

Discovery of novel 2-hydroxyl-4-benzyloxybenzyl aniline derivatives as potential multifunctional agents for the treatment of Parkinson's disease

To discover novel multifunctional agents for the treatment of Parkinson's disease, a series of 2-hydroxyl-4-benzyloxybenzyl aniline derivatives was designed, synthesized and evaluated. The biological screening indicated that representative compound 6h possessed excellent MAO-B inhibition (IC₅₀ = 0.014 μM), high antioxidant activity (ORAC = 2.14 Trolox equivalent), good metal chelating ability, appropriate BBB permeability and significant neuroprotective effect. Additionally, 6h exhibited great ability to alleviate the neuroinflammtion by suppressing the activation of NF-κB pathway in vitro. Furthermore, 6h can also ameliorate MPTP induced Parkinson's disease symptoms in mice by improving the dopamine level and repressing oxidative damage. These results indicated that compound 6h was a promising candidate for further development against PD.

Protective mechanisms by glial cell line-derived neurotrophic factor and cerebral dopamine neurotrophic factor against the α-synuclein accumulation in Parkinson's disease

Synucleinopathies constitute a disease family named after alpha-synuclein protein, which is a significant component of the intracellular inclusions called Lewy bodies. Accompanying the progressive neurodegeneration, Lewy bodies and neurites are the main histopathologies of synucleinopathies. The complicated role of alpha-synuclein in the disease pathology makes it an attractive therapeutic target for disease-modifying treatments. GDNF is one of the most potent neurotrophic factors for dopamine neurons, whereas CDNF is protective and neurorestorative with entirely different mechanisms of action. Both have been in the clinical trials for the most common synucleinopathy, Parkinson's disease. With the AAV-GDNF clinical trials ongoing and the CDNF trial being finalized, their effects on abnormal alpha-synuclein accumulation are of great interest. Previous animal studies with an alpha-synuclein overexpression model have shown that GDNF was ineffective against alpha-synuclein accumulation. However, a recent study with cell culture and animal models of alpha-synuclein fibril inoculation has demonstrated the opposite by revealing that the GDNF/RET signaling cascade is required for the protective effect of GDNF on alpha-synuclein aggregation. CDNF, an ER resident protein, was shown to bind alpha-synuclein directly. CDNF reduced the uptake of alpha-synuclein fibrils by the neurons and alleviated the behavioral deficits induced by fibrils injected into the mouse brain. Thus, GDNF and CDNF can modulate different symptoms and pathologies of Parkinson's disease, and perhaps, similarly for other synucleinopathies. Their unique mechanisms for preventing alpha-synuclein-related pathology should be studied more carefully to develop disease-modifying therapies.

[Parkinson's disease and Alzheimer type dementia-Pathophysiology and drug treatment approaches]

Symptomatically effective forms of treatment for neurodegenerative diseases have been developed in the last 50 years based on the knowledge about the pathophysiological and neurochemical context in the central nervous system. These so far represent the basis of available treatment options. Knowledge of the pathophysiological and neurochemical context, however, is not only necessary for the development of treatment but also enables a meaningful implementation of currently available substances. The most important neuropathological and neurochemical alterations that characterize Parkinson's disease and Alzheimer type dementia are briefly presented. In recent years, new substances ranging from symptomatic to disease-modifying treatment options have been developed, the latter mostly based on the neuropathologically detectable alterations. Recent results from clinical studies raise hopes that disease-modifying treatment options for neurodegenerative diseases will become available in the foreseeable future.

How should future clinical trials be designed in the search for disease-modifying therapies for Parkinson's disease?

INTRODUCTION

Although there has been substantial progress in research and innovations in symptomatic treatments, similar success has not been achieved in disease-modifying therapy (DMT) for Parkinson's disease (PD). Considering the enormous motor, psychosocial and financial burden associated with PD, safe and effective DMT is of paramount importance.

AREAS COVERED

One of the reasons for the lack of progress in DMT for PD is poor or inappropriate design of clinical trials. In the first part of the article, the authors focus on the plausible reasons why the previous trials have failed and in the latter part, they provide their perspectives on future DMT trials.

EXPERT OPINION

There are several potential reasons why previous trials have failed, including broad clinical and etiopathogenic heterogeneity of PD, poor definition and documentation of target engagement, lack of appropriate biomarkers and outcome measures, and short duration of follow-up. To address these deficiencies, future trials may consider- (i) a more customized approach to select the most suitable participants and therapeutic approaches, (ii) explore combination therapies that would target multiple pathogenetic mechanisms, and (iii) moving beyond targeting only motor symptoms to also assessing non-motor features of PD in well-designed longitudinal studies.

Neuroinflammation, immune response and α-synuclein pathology: how animal models are helping us to connect dots

INTRODUCTION

A key pathological event occurring in Parkinson's disease (PD) is the transneuronal spreading of alpha-synuclein (α-syn). Other hallmarks of PD include neurodegeneration, glial activation, and immune cell infiltration in susceptible brain regions. Although preclinical models can mimic most of the key characteristics of PD, it is crucial to know the biological bases of individual differences between them when choosing one over another, to ensure proper interpretation of the results and to positively influence the outcome of the experiments.

AREAS COVERED

This review provides an overview of current preclinical models actively used to study the interplay between α-syn pathology, neuroinflammation and immune response in PD but also to explore new potential preclinical models or emerging therapeutic strategies intended to fulfill the unmet medical needs in this disease. Lastly, this review also considers the current state of the ongoing clinical trials of new drugs designed to target these processes and delay the initiation or progression of the disease.

EXPERT OPINION

Anti-inflammatory and immunomodulatory agents have been demonstrated to be very promising candidates for reducing disease progression; however, more efforts are needed to reduce the enormous gap between these and dopaminergic drugs, which have dominated the therapeutic market for the last sixty years.

A Mouse Model to Test Novel Therapeutics for Parkinson's Disease: an Update on the Thy1-aSyn ("line 61") Mice

Development of neuroprotective therapeutics for Parkinson's disease (PD) is facing a lack of translation from pre-clinical to clinical trials. One strategy for improvement is to increase predictive validity of pre-clinical studies by using extensively characterized animal models with a comprehensive set of validated pharmacodynamic readouts. Mice over-expressing full-length, human, wild-type alpha-synuclein under the Thy-1 promoter (Thy1-aSyn line 61) reproduce key features of sporadic PD, such as progressive loss of striatal dopamine, alpha-synuclein pathology, deficits in motor and non-motor functions, and elevation of inflammatory markers. Extensive work with this model by multiple laboratories over the past decade further increased confidence in its robustness and validity, especially for analyzing pathomechanisms of alpha-synuclein pathology and down-stream pathways, and for pre-clinical drug testing. Interestingly, while postnatal transgene expression is widespread in central and peripheral neurons, the extent and progression of down-stream pathology differs between brain regions, thereby replicating the characteristic selective vulnerability of neurodegenerative diseases. In-depth characterization of these readouts in conjunction with behavioral deficits has led to more informative endpoints for pre-clinical trials. Each drug tested in Thy1-aSyn line 61 enhances knowledge on how molecular targets, pathology, and functional behavioral readouts are interconnected, thereby further optimizing the platform towards predictive validity for clinical trials. Here, we present the current state of the art using Thy1-aSyn line 61 for drug target discovery, validation, and pre-clinical testing.

Co-administration of Nanowired DL-3-n-Butylphthalide (DL-NBP) Together with Mesenchymal Stem Cells, Monoclonal Antibodies to Alpha Synuclein and TDP-43 (TAR DNA-Binding Protein 43) Enhance Superior Neuroprotection in Parkinson's Disease Following Concussive Head Injury

dl-3-n-butylphthalide (dl-NBP) is one of the potent antioxidant compounds that induces profound neuroprotection in stroke and traumatic brain injury. Our previous studies show that dl-NBP reduces brain pathology in Parkinson's disease (PD) following its nanowired delivery together with mesenchymal stem cells (MSCs) exacerbated by concussive head injury (CHI). CHI alone elevates alpha synuclein (ASNC) in brain or cerebrospinal fluid (CSF) associated with elevated TAR DNA-binding protein 43 (TDP-43). TDP-43 protein is also responsible for the pathologies of PD. Thus, it is likely that exacerbation of brain pathology in PD following brain injury may be thwarted using nanowired delivery of monoclonal antibodies (mAb) to ASNC and/or TDP-43. In this review, the co-administration of dl-NBP with MSCs and mAb to ASNC and/or TDP-43 using nanowired delivery in PD and CHI-induced brain pathology is discussed based on our own investigations. Our observations show that co-administration of TiO2 nanowired dl-NBP with MSCs and mAb to ASNC with TDP-43 induced superior neuroprotection in CHI induced exacerbation of brain pathology in PD, not reported earlier.

3α,7-Dihydroxy-14(13→12)abeo-5β,12α(H),13β(H)-cholan-24-oic Acids Display Neuroprotective Properties in Common Forms of Parkinson's Disease

Parkinson's Disease is the most common neurodegenerative movement disorder globally, with prevalence increasing. There is an urgent need for new therapeutics which are disease-modifying rather than symptomatic. Mitochondrial dysfunction is a well-documented mechanism in both sporadic and familial Parkinson's Disease. Furthermore, ursodeoxycholic acid (UDCA) has been identified as a bile acid which leads to increased mitochondrial function in multiple in vitro and in vivo models of Parkinson's Disease. Here, we describe the synthesis of novel C-nor-D-homo bile acid derivatives and the 12-hydroxy-methylated derivative of lagocholic acid (7) and their biological evaluation in fibroblasts from patients with either sporadic or LRRK2 mutant Parkinson's Disease. These compounds boost mitochondrial function to a similar level or above that of UDCA in many assays; notable, however, is their ability to boost mitochondrial function to a higher level and at lower concentrations than UDCA specifically in the fibroblasts from LRRK2 patients. Our study indicates that novel bile acid chemistry could lead to the development of more efficacious bile acids which increase mitochondrial function and ultimately cellular health at lower concentrations proving attractive potential novel therapeutics for Parkinson's Disease.

Precision medicine for Parkinson's disease: The subtyping challenge

Despite many pharmacological and surgical treatments addressing the symptoms of Parkinson's disease, there are no approved treatments that slow disease progression. Genetic discoveries in the last 20 years have increased our understanding of the molecular contributors to Parkinson's pathophysiology, uncovered many druggable targets and pathways, and increased investment in treatments that might slow or stop the disease process. Longitudinal, observational studies are dissecting Parkinson's disease heterogeneity and illuminating the importance of molecularly defined subtypes more likely to respond to targeted interventions. Indeed, clinical and pathological differences seen within and across carriers of PD-associated gene mutations suggest the existence of greater biological complexity than previously appreciated and increase the likelihood that targeted interventions based on molecular characteristics will be beneficial. This article offers our current perspective on the promise and current challenges in subtype identification and precision medicine approaches in Parkinson's disease.

Protein and Gene Delivery Systems for Neurodegenerative Disorders: Where Do We Stand Today?

It has been estimated that every year, millions of people are affected by neurodegenerative disorders, which complicate their lives and their caregivers' lives. To date, there has not been an approved pharmacological approach to provide the complete treatment of neurodegenerative disorders. The only available drugs may only relieve the symptoms or slow down the progression of the disease. The absence of any treatment is quite rational given that neurodegeneration occurs by the progressive loss of the function or structure of the nerve cells of the brain or the peripheral nervous system, which eventually leads to their death either by apoptosis or necrotic cell death. According to a recent study, even though adult brain cells are injured, they can revert to an embryonic state, which may help to restore their function. These interesting findings might open a new path for the development of more efficient therapeutic strategies to combat devastating neurodegenerative disorders. Gene and protein therapies have emerged as a rapidly growing field for various disorders, especially neurodegenerative diseases. Despite these promising therapies, the complete treatment of neurodegenerative disorders has not yet been achieved. Therefore, the aim of this review is to address the most up-to-date data for neurodegenerative diseases, but most importantly, to summarize the available delivery systems incorporating proteins, peptides, and genes that can potentially target such diseases and pass into the blood-brain barrier. The authors highlight the advancements, at present, on delivery based on the carrier, i.e., lipid, polymeric, and inorganic, as well as the recent studies on radiopharmaceutical theranostics.

Defining the unknowns for cell therapies in Parkinson's disease

First-in-human clinical trials have commenced to test the safety and efficacy of cell therapies for people with Parkinson's disease (PD). Proof of concept that this neural repair strategy is efficacious is based on decades of preclinical studies and clinical trials using primary foetal cells, as well as a significant literature exploring more novel stem cell-derived products. Although several measures of efficacy have been explored, including the successful in vitro differentiation of stem cells to dopamine neurons and consistent alleviation of motor dysfunction in rodent models, many unknowns still remain regarding the long-term clinical implications of this treatment strategy. Here, we consider some of these outstanding questions, including our understanding of the interaction between anti-Parkinsonian medication and the neural transplant, the impact of the cell therapy on cognitive or neuropsychiatric symptoms of PD, the role of neuroinflammation in the therapeutic process and the development of graft-induced dyskinesias. We identify questions that are currently pertinent to the field that require further exploration, and pave the way for a more holistic understanding of this neural repair strategy for treatment of PD.