Tryptophan residues in TDP-43 and SOD1 modulate the cross-seeding and toxicity of SOD1.

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease of motor neurons. Neuronal superoxide dismutase-1 (SOD1) inclusion bodies are characteristic of familial ALS with SOD1 mutations, while a hallmark of sporadic ALS is inclusions containing aggregated WT TAR DNA-binding protein 43 (TDP-43). We show here that co-expression of mutant or WT TDP-43 with SOD1 leads to misfolding of endogenous SOD1 and aggregation of SOD1 reporter protein SOD1G85R-GFP in human cell cultures and promotes synergistic axonopathy in zebrafish. Intriguingly, this pathological interaction is modulated by natively solvent-exposed tryptophans in SOD1 (tryptophan-32) and TDP-43 RNA-recognition motif RRM1 (tryptophan-172), in concert with natively sequestered TDP-43 N-terminal domain tryptophan-68. TDP-43 RRM1 intrabodies reduce WT SOD1 misfolding in human cell cultures, via blocking tryptophan-172. Tryptophan-68 becomes antibody-accessible in aggregated TDP-43 in sporadic ALS motor neurons and cell culture. 5-fluorouridine inhibits TDP-43-induced G85R-GFP SOD1 aggregation in human cell cultures and ameliorates axonopathy in zebrafish, via its interaction with SOD1 tryptophan-32. Collectively, our results establish a novel and potentially druggable tryptophan-mediated mechanism whereby two principal ALS disease effector proteins might directly interact in disease.

Diagnosis of manganism and manganese neurotoxicity: A workshop report.

With declining exposures to manganese (Mn) in occupational settings, there is a need for more sensitive exposure assessments and clinical diagnostic criteria for manganism and Mn neurotoxicity. To address this issue, a workshop was held on November 12-13, 2020, with international experts on Mn toxicity. The workshop discussions focused on the history of the diagnostic criteria for manganism, including those developed by the Institut de Recherche Robert-Sauvé en Santé et en Sécurité du Travail (IRSST) in Quebec in 2005 and criteria developed by the Chinese government in 2002 and updated in 2006; the utility of biomarkers of exposure; recent developments in magnetic resonance imaging (MRI) for assessing Mn accumulation in the brain and diagnosing manganism; and potential future applications of metabolomics. The suggestions of the participants for updating manganism diagnostic criteria included the consideration of: i) A history of previous occupational and environmental exposure to Mn; ii) relevant clinical symptoms such as dystonia; iii) MRI imaging to document Mn accumulation in the neural tissues, including the basal ganglia; and iv) criteria for the differential diagnosis of manganism and other neurological conditions. Important research gaps include the characterization of Mn exposure and other co-exposures, exploration of the roles of different brain regions with MRI, understanding the complexity of metal ion transporters involved in Mn homeostasis, and a need for information on other neurotransmitter systems and brain regions underlying the pathophysiology of manganism.

Should we screen aging physicians for cognitive decline?

OBJECTIVES: To synthesize evidence relevant for informed decisions concerning cognitive testing of older physicians. METHODS: Relevant literature was systematically searched in Medline, EMBASE, PsycInfo, and ERIC, with key findings abstracted and synthesized. RESULTS: Cognitive abilities of physicians may decline in an age range where they are still practicing. Physician competence and clinical performance may also decline with age. Cognitive scores are lower in physicians referred for assessment because of competency or performance concerns. Many physicians do not accurately self-assess and continue to practice despite declining quality of care; however, perceived cognitive decline, although not an accurate indicator of ability, may accelerate physicians' decision to retire. Physicians are reluctant to report colleagues' cognitive problems. Several issues should be considered in implementing cognitive screening. Most cognitive assessment tools lack normative data for physicians. Scientific evidence linking cognitive test results with physician performance is limited. There is no known level of cognitive decline at which a doctor is no longer fit to practice. Finally, relevant domains of cognitive ability vary across medical specialties. CONCLUSION: Physician cognitive decline may impact clinical performance. If cognitive assessment of older physicians is to be implemented, it should consider challenges of cognitive test result interpretation.

Targeting RACK1 to alleviate TDP-43 and FUS proteinopathy-mediated suppression of protein translation and neurodegeneration.

TAR DNA-binding protein 43 (TDP-43) and Fused in Sarcoma/Translocated in Sarcoma (FUS) are ribonucleoproteins associated with pathogenesis of amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration (FTLD). Under physiological conditions, TDP-43 and FUS are predominantly localized in the nucleus, where they participate in transcriptional regulation, RNA splicing and metabolism. In disease, however, they are typically mislocalized to the cytoplasm where they form aggregated inclusions. A number of shared cellular pathways have been identified that contribute to TDP-43 and FUS toxicity in neurodegeneration. In the present study, we report a novel pathogenic mechanism shared by these two proteins. We found that pathological FUS co-aggregates with a ribosomal protein, the Receptor for Activated C-Kinase 1 (RACK1), in the cytoplasm of spinal cord motor neurons of ALS, as previously reported for pathological TDP-43. In HEK293T cells transiently transfected with TDP-43 or FUS mutant lacking a functional nuclear localization signal (NLS; TDP-43ΔNLS and FUSΔNLS), cytoplasmic TDP-43 and FUS induced co-aggregation with endogenous RACK1. These co-aggregates sequestered the translational machinery through interaction with the polyribosome, accompanied by a significant reduction of global protein translation. RACK1 knockdown decreased cytoplasmic aggregation of TDP-43ΔNLS or FUSΔNLS and alleviated associated global translational suppression. Surprisingly, RACK1 knockdown also led to partial nuclear localization of TDP-43ΔNLS and FUSΔNLS in some transfected cells, despite the absence of NLS. In vivo, RACK1 knockdown alleviated retinal neuronal degeneration in transgenic Drosophila melanogaster expressing hTDP-43WT or hTDP-43Q331K and improved motor function of hTDP-43WT flies, with no observed adverse effects on neuronal health in control knockdown flies. In conclusion, our results revealed a novel shared mechanism of pathogenesis for misfolded aggregates of TDP-43 and FUS mediated by interference with protein translation in a RACK1-dependent manner. We provide proof-of-concept evidence for targeting RACK1 as a potential therapeutic approach for TDP-43 or FUS proteinopathy associated with ALS and FTLD.

Shift of the insoluble content of the proteome in the aging mouse brain.

During aging, the cellular response to unfolded proteins is believed to decline, resulting in diminished proteostasis. In model organisms, such as Caenorhabditis elegans, proteostatic decline with age has been linked to proteome solubility shifts and the onset of protein aggregation. However, this correlation has not been extensively characterized in aging mammals. To uncover age-dependent changes in the insoluble portion of a mammalian proteome, we analyzed the detergent-insoluble fraction of mouse brain tissue by mass spectrometry. We identified a group of 171 proteins, including the small heat shock protein α-crystallin, that become enriched in the detergent-insoluble fraction obtained from old mice. To enhance our ability to detect features associated with proteins in that fraction, we complemented our data with a meta-analysis of studies reporting the detergent-insoluble proteins in various mouse models of aging and neurodegeneration. Strikingly, insoluble proteins from young and old mice are distinct in several features in our study and across the collected literature data. In younger mice, proteins are more likely to be disordered, part of membraneless organelles, and involved in RNA binding. These traits become less prominent with age, as an increased number of structured proteins enter the pellet fraction. This analysis suggests that age-related changes to proteome organization lead a group of proteins with specific features to become detergent-insoluble. Importantly, these features are not consistent with those associated with proteins driving membraneless organelle formation. We see no evidence in our system of a general increase of condensate proteins in the detergent-insoluble fraction with age.

Primary lateral sclerosis.

Like motor neuron diseases (MNDs) refer to a constellation of primarily sporadic neurodegenerative diseases characterized by a progressive loss of upper and/or lower motor neurons. Primary lateral sclerosis (PLS) is considered a neurodegenerative disorder that is characterized by a gradually progressive course affecting the central motor systems, designated by the phrase "upper motor neurons." Despite significant development in neuroimaging, neurophysiology, and molecular biology, there is a growing consensus that PLS is of unknown etiology. Currently there is no disease-modifying treatment for PLS, or prospective randomized trials being carried out, partly due to the rarity of the disease and lack of significant understanding of the underlying pathophysiology. Consequently, the approach to treatment remains largely symptomatic. In this chapter we provide an overview of primary lateral sclerosis including clinical and electrodiagnostic considerations, differential diagnosis, updates in genetics and pathophysiology, and future directions for research.

De Novo Design of a ß-Helix Tau Protein Scaffold: An Oligomer-Selective Vaccine Immunogen Candidate for Alzheimer's Disease.

Tau pathology is associated with many neurodegenerative disorders, including Alzheimer's disease (AD), where the spatio-temporal pattern of tau neurofibrillary tangles strongly correlates with disease progression, which motivates therapeutics selective for misfolded tau. Here, we introduce a new avidity-enhanced, multi-epitope approach for protein-misfolding immunogen design, which is predicted to mimic the conformational state of an exposed epitope in toxic tau oligomers. A predicted oligomer-selective tau epitope 343KLDFK347 was scaffolded by designing a ß-helix structure that incorporated multiple instances of the 16-residue tau fragment 339VKSEKLDFKDRVQSKI354. Large-scale conformational ensemble analyses involving Jensen-Shannon Divergence and the embedding depth D showed that the multi-epitope scaffolding approach, employed in designing the ß-helix scaffold, was predicted to better discriminate toxic tau oligomers than other "monovalent" strategies utilizing a single instance of an epitope for vaccine immunogen design. Using Rosetta, 10,000 sequences were designed and screened for the linker portions of the ß-helix scaffold, along with a C-terminal stabilizing α-helix that interacts with the linkers, to optimize the folded structure and stability of the scaffold. Structures were ranked by energy, and the lowest 1% (82 unique sequences) were verified using AlphaFold. Several selection criteria involving AlphaFold are implemented to obtain a lead-designed sequence. The structure was further predicted to have free energetic stability by using Hamiltonian replica exchange molecular dynamics (MD) simulations. The synthesized ß-helix scaffold showed direct binding in surface plasmon resonance (SPR) experiments to several antibodies that were raised to the structured epitope using a designed cyclic peptide. Moreover, the strength of binding of these antibodies to in vitro tau oligomers correlated with the strength of binding to the ß-helix construct, suggesting that the construct presents an oligomer-like conformation and may thus constitute an effective oligomer-selective immunogen.

A Systematic Review of the Genetics and Pathology of Psychosis in Frontotemporal Dementia.

OBJECTIVES: Frontotemporal dementia (FTD) patients frequently present with psychosis, which complicates diagnosis and management. In this study, we aim to examine the relationship between psychosis and the most common genetic mutations predisposing to FTD, and in the different pathological subtypes of FTD. DESIGN: We conducted a systematic review, searching the literature up to December 2022, and reviewed 50 articles that met our inclusion criteria. From the reviewed articles, we extracted and summarized data regarding the frequency of psychosis and patient characteristics in each major genetic and pathological subtype of FTD. RESULTS: Among FTD patients with confirmed genetic mutations or pathological diagnosss, the frequency of psychosis was 24.2%. Among the genetic mutation carriers, C9orf72 mutation carriers had the highest frequency of psychosis (31.4%), whereas GRN (15.0%) and MAPT (9.2%) mutation carriers had lower frequencies of psychosis. MAPT mutation carriers notably developed psychosis at a younger age compared to other genetic groups. The most common psychotic symptoms were delusions among C9orf72 carriers and visual hallucinations among GRN mutation carriers. Among the pathological subtypes, 30% of patients with FUS pathology, 25.3% of patients with TDP-43 pathology, and 16.4% of patients with tau pathology developed psychosis. In the TDP-43 group, subtype B pathology was the most common subtype reported in association with psychosis. CONCLUSION: Our systematic review suggests a high frequency of psychosis in specific subgroups of FTD patients. Further studies are required to understand the structural and biological underpinnings of psychosis in FTD.

Assessment of protein inclusions in cultured cells using automated image analysis.

Proteinaceous inclusions are associated with neurodegenerative diseases and cell models are often used to determine genetic and chemical modifiers of their formation. This protocol involves the usage of automated microscopy and machine learning-based image analysis to accurately quantify the levels of protein inclusion formation in cultured cells from fluorescence microscopy images. This protocol is highly scalable and can be applied to a few images or large datasets. For complete details on the use and execution of this protocol, please refer to McAlary et al. (2022).

Rational Generation of Monoclonal Antibodies Selective for Pathogenic Forms of Alpha-Synuclein.

Misfolded toxic forms of alpha-synuclein (α-Syn) have been implicated in the pathogenesis of synucleinopathies, including Parkinson's disease (PD), dementia with Lewy bodies (DLB), and multiple system atrophy (MSA). The α-Syn oligomers and soluble fibrils have been shown to mediate neurotoxicity and cell-to-cell propagation of pathology. To generate antibodies capable of selectively targeting pathogenic forms of α-Syn, computational modeling was used to predict conformational epitopes likely to become exposed on oligomers and small soluble fibrils, but not on monomers or fully formed insoluble fibrils. Cyclic peptide scaffolds reproducing these conformational epitopes exhibited neurotoxicity and seeding activity, indicating their biological relevance. Immunization with the conformational epitopes gave rise to monoclonal antibodies (mAbs) with the desired binding profile showing selectivity for toxic α-Syn oligomers and soluble fibrils, with little or no reactivity with monomers, physiologic tetramers, or Lewy bodies. Recognition of naturally occurring soluble α-Syn aggregates in brain extracts from DLB and MSA patients was confirmed by surface plasmon resonance (SPR). In addition, the mAbs inhibited the seeding activity of sonicated pre-formed fibrils (PFFs) in a thioflavin-T fluorescence-based aggregation assay. In neuronal cultures, the mAbs protected primary rat neurons from toxic α-Syn oligomers, reduced the uptake of PFFs, and inhibited the induction of pathogenic phosphorylated aggregates of endogenous α-Syn. Protective antibodies selective for pathogenic species of α-Syn, as opposed to pan α-Syn reactivity, are expected to provide enhanced safety and therapeutic potency by preserving normal α-Syn function and minimizing the diversion of active antibody from the target by the more abundant non-toxic forms of α-Syn in the circulation and central nervous system.

Optimizing Epitope Conformational Ensembles Using α-Synuclein Cyclic Peptide "Glycindel" Scaffolds: A Customized Immunogen Method for Generating Oligomer-Selective Antibodies for Parkinson's Disease.

Effectively presenting epitopes on immunogens, in order to raise conformationally selective antibodies through active immunization, is a central problem in treating protein misfolding diseases, particularly neurodegenerative diseases such as Alzheimer's disease or Parkinson's disease. We seek to selectively target conformations enriched in toxic, oligomeric propagating species while sparing the healthy forms of the protein that are often more abundant. To this end, we computationally modeled scaffolded epitopes in cyclic peptides by inserting/deleting a variable number of flanking glycines ("glycindels") to best mimic a misfolding-specific conformation of an epitope of α-synuclein enriched in the oligomer ensemble, as characterized by a region most readily disordered and solvent-exposed in a stressed, partially denatured protofibril. We screen and rank the cyclic peptide scaffolds of α-synuclein in silico based on their ensemble overlap properties with the fibril, oligomer-model and isolated monomer ensembles. We present experimental data of seeded aggregation that support nucleation rates consistent with computationally predicted cyclic peptide conformational similarity. We also introduce a method for screening against structured off-pathway targets in the human proteome by selecting scaffolds with minimal conformational similarity between their epitope and the same solvent-exposed primary sequence in structured human proteins. Different cyclic peptide scaffolds with variable numbers of glycines are predicted computationally to have markedly different conformational ensembles. Ensemble comparison and overlap were quantified by the Jensen-Shannon divergence and a new measure introduced here, the embedding depth, which determines the extent to which a given ensemble is subsumed by another ensemble and which may be a more useful measure in developing immunogens that confer conformational selectivity to an antibody.

P2X7 receptor activation mediates superoxide dismutase 1 (SOD1) release from murine NSC-34 motor neurons.

Mutant superoxide dismutase 1 (SOD1) can be constitutively released from motor neurons and transmitted to naïve motor neurons to promote the progression of amyotrophic lateral sclerosis (ALS). However, the biological impacts of this process and the precise mechanisms of SOD1 release remain to be fully resolved. Using biochemical and fluorescent techniques, this study aimed to determine if P2X7 receptor activation could induce mutant SOD1 release from motor neurons and whether this released SOD1 could be transmitted to motor neurons or microglia to mediate effects associated with neurodegeneration in ALS. Aggregated SOD1G93A, released from murine NSC-34 motor neurons transiently transfected with SOD1G93A, could be transmitted to naïve NSC-34 cells and murine EOC13 microglia to induce endoplasmic reticulum (ER) stress and tumour necrosis factor-alpha (TNFα) release, respectively. Immunoblotting revealed NSC-34 cells expressed P2X7. Extracellular ATP induced cation dye uptake into these cells, which was blocked by the P2X7 antagonist AZ10606120, demonstrating these cells express functional P2X7. Moreover, ATP induced the rapid release of aggregated SOD1G93A from NSC-34 cells transiently transfected with SOD1G93A, a process blocked by AZ10606120 and revealing a role for P2X7 in this process. ATP-induced SOD1G93A release coincided with membrane blebbing. Finally, aggregated SOD1G93A released via P2X7 activation could also be transmitted to NSC-34 and EOC13 cells to induce ER stress and TNFα release, respectively. Collectively, these results identify a novel role for P2X7 in the prion-like propagation of SOD1 in ALS and provide a possible explanation for the therapeutic benefits of P2X7 antagonism previously observed in ALS SOD1G93A mice.

Sublethal enteroviral infection exacerbates disease progression in an ALS mouse model.

BACKGROUND: Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease of the motor neuron system associated with both genetic and environmental risk factors. Infection with enteroviruses, including poliovirus and coxsackievirus, such as coxsackievirus B3 (CVB3), has been proposed as a possible causal/risk factor for ALS due to the evidence that enteroviruses can target motor neurons and establish a persistent infection in the central nervous system (CNS), and recent findings that enteroviral infection-induced molecular and pathological phenotypes closely resemble ALS. However, a causal relationship has not yet been affirmed. METHODS: Wild-type C57BL/6J and G85R mutant superoxide dismutase 1 (SOD1G85R) ALS mice were intracerebroventricularly infected with a sublethal dose of CVB3 or sham-infected. For a subset of mice, ribavirin (a broad-spectrum anti-RNA viral drug) was given subcutaneously during the acute or chronic stage of infection. Following viral infection, general activity and survival were monitored daily for up to week 60. Starting at week 20 post-infection (PI), motor functions were measured weekly. Mouse brains and/or spinal cords were harvested at day 10, week 20 and week 60 PI for histopathological evaluation of neurotoxicity, immunohistochemical staining of viral protein, neuroinflammatory/immune and ALS pathology markers, and NanoString and RT-qPCR analysis of inflammatory gene expression. RESULTS: We found that sublethal infection (mimicking chronic infection) of SOD1G85R ALS mice with CVB3 resulted in early onset and progressive motor dysfunction, and shortened lifespan, while similar viral infection in C57BL/6J, the background strain of SOD1G85R mice, did not significantly affect motor function and mortality as compared to mock infection within the timeframe of the current study (60 weeks PI). Furthermore, we showed that CVB3 infection led to a significant increase in proinflammatory gene expression and immune cell infiltration and induced ALS-related pathologies (i.e., TAR DNA-binding protein 43 (TDP-43) pathology and neuronal damage) in the CNS of both SOD1G85R and C57BL/6J mice. Finally, we discovered that early (day 1) but not late (day 15) administration of ribavirin could rescue ALS-like neuropathology and symptoms induced by CVB3 infection. CONCLUSIONS: Our study identifies a new risk factor that contributes to early onset and accelerated progression of ALS and offers opportunities for the development of novel targeted therapies.

A novel multiplex electrochemiluminescent immunoassay for detection and quantification of anti-SARS-CoV-2 IgG and anti-seasonal endemic human coronavirus IgG.

BACKGROUND: Multiplex immunoassays capture a comprehensive profile of the humoral response against SARS-CoV-2 and human endemic coronaviruses. We validated a multiplex panel (V-PLEX Panel 2) from Meso Scale Diagnostics targeting antibodies against nine coronavirus antigens. Performance was compared against alternative single- and multi-antigen immunoassays. METHODS: Sera collected for clinical or public health testing from 2018 to 2020 (n = 135) were used to compare all tested platforms, and inter-test agreement was assessed by Cohen's kappa coefficient. Sample category (positive/negative) was assigned based on collection date relative to the index case in Canada, and SARS-CoV-2 PCR and serology results. 117 out of the 135 samples (31 positive, 86 negative) were assigned a category and were used to calculate sensitivity and specificity, with MSD's test results based upon manufacturer-set cut-offs. RESULTS: We observed SARS-CoV-2 target sensitivities of 100% and specificities >94% for all antigens (RBD, Nucleocapsid, Spike) in V-PLEX Panel 2. When targets were combined, we found a SARS-CoV-2 sensitivity of 100% and specificity of 98.8% with no difference in performance compared to clinical assays, and Cohen's kappa ranging from 0.798 to 0.945 compared to surface plasmon resonance imaging (SPRi). Quantitative measurements of antibodies against the Spike protein of endemic human coronaviruses were concordant with SPRi. CONCLUSION: Meso Scale Diagnostics' V-PLEX Coronavirus Panel 2 allows for highly sensitive and specific detection of anti-coronavirus IgG, and is concordant with other serological assays for detection of antibodies against SARS-CoV-2 and the endemic human coronaviruses, making it a good tool for humoral response characterization after both infection and vaccination.

A method for systematically ranking therapeutic drug candidates using multiple uncertain screening criteria.

Multiple different screening tests for candidate leads in drug development may often yield conflicting or ambiguous results, sometimes making the selection of leads a nontrivial maximum-likelihood ranking problem. Here, we employ methods from the field of multiple criteria decision making (MCDM) to the problem of screening candidate antibody therapeutics. We employ the SMAA-TOPSIS method to rank a large cohort of antibodies using up to eight weighted screening criteria, in order to find lead candidate therapeutics for Alzheimer's disease, and determine their robustness to both uncertainty in screening measurements, as well as uncertainty in the user-defined weights of importance attributed to each screening criterion. To choose lead candidates and measure the confidence in their ranking, we propose two new quantities, the Retention Probability and the Topness, as robust measures for ranking. This method may enable more systematic screening of candidate therapeutics when it becomes difficult intuitively to process multi-variate screening data that distinguishes candidates, so that additional candidates may be exposed as potential leads, increasing the likelihood of success in downstream clinical trials. The method properly identifies true positives and true negatives from synthetic data, its predictions correlate well with known clinically approved antibodies vs. those still in trials, and it allows for ranking analyses using antibody developability profiles in the literature. We provide a webserver where users can apply the method to their own data: http://bjork.phas.ubc.ca.

Development of an α-synuclein knockdown peptide and evaluation of its efficacy in Parkinson's disease models.

Convincing evidence supports the premise that reducing α-synuclein levels may be an effective therapy for Parkinson's disease (PD); however, there has been lack of a clinically applicable α-synuclein reducing therapeutic strategy. This study was undertaken to develop a blood-brain barrier and plasma membrane-permeable α-synuclein knockdown peptide, Tat-ßsyn-degron, that may have therapeutic potential. The peptide effectively reduced the level of α-synuclein via proteasomal degradation both in cell cultures and in animals. Tat-ßsyn-degron decreased α-synuclein aggregates and microglial activation in an α-synuclein pre-formed fibril model of spreading synucleinopathy in transgenic mice overexpressing human A53T α-synuclein. Moreover, Tat-ßsyn-degron reduced α-synuclein levels and significantly decreased the parkinsonian toxin-induced neuronal damage and motor impairment in a mouse toxicity model of PD. These results show the promising efficacy of Tat-ßsyn-degron in two different animal models of PD and suggest its potential use as an effective PD therapeutic that directly targets the disease-causing process.

Tardive neurotoxicity of anticholinergic drugs: A review.

The cholinergic system is a complex neurotransmitter system with functional involvement at multiple levels of the nervous system including the cerebral cortex, spinal cord, autonomic nervous system, and neuromuscular junction. Anticholinergic medications are among the most prescribed medications, making up one-third to one-half of all medications prescribed for seniors. Recent evidence has linked long-term use of anticholinergic medications and dementia. Emerging evidence implicates the cholinergic system in the regulation of cerebral vasculature as well as neuroinflammation, suggesting that anticholinergic medications may contribute to absolute risk and progression of neurodegenerative diseases. In this review, we explore the involvement of the cholinergic system in various neurodegenerative diseases and the possible detrimental effects of anticholinergic medications on the onset and progression of these disorders. We identified references by searching the PubMed and Cochrane database between January 1990 and September 2019 for English-language animal and human studies including randomized clinical trials (RCTs), meta-analyses, systematic reviews, and observational studies. In addition, we conducted a manual search of reference lists from retrieved studies. Long-term anticholinergic medication exposure may have detrimental consequences beyond well-documented short-term cognitive effects, through a variety of mechanisms either directly impacting cholinergic neurotransmission or through receptors expressed on the vasculature or immune cells, providing a pathophysiological framework for complex interactions across the entire neuroaxis.

Amyotrophic Lateral Sclerosis: Proteins, Proteostasis, Prions, and Promises.

Amyotrophic lateral sclerosis (ALS) is characterized by the progressive degeneration of the motor neurons that innervate muscle, resulting in gradual paralysis and culminating in the inability to breathe or swallow. This neuronal degeneration occurs in a spatiotemporal manner from a point of onset in the central nervous system (CNS), suggesting that there is a molecule that spreads from cell-to-cell. There is strong evidence that the onset and progression of ALS pathology is a consequence of protein misfolding and aggregation. In line with this, a hallmark pathology of ALS is protein deposition and inclusion formation within motor neurons and surrounding glia of the proteins TAR DNA-binding protein 43, superoxide dismutase-1, or fused in sarcoma. Collectively, the observed protein aggregation, in conjunction with the spatiotemporal spread of symptoms, strongly suggests a prion-like propagation of protein aggregation occurs in ALS. In this review, we discuss the role of protein aggregation in ALS concerning protein homeostasis (proteostasis) mechanisms and prion-like propagation. Furthermore, we examine the experimental models used to investigate these processes, including in vitro assays, cultured cells, invertebrate models, and murine models. Finally, we evaluate the therapeutics that may best prevent the onset or spread of pathology in ALS and discuss what lies on the horizon for treating this currently incurable disease.

Passive immunotherapies targeting Aß and tau in Alzheimer's disease.

Amyloid-ß (Aß) and tau proteins currently represent the two most promising targets to treat Alzheimer's disease. The most extensively developed method to treat the pathologic forms of these proteins is through the administration of exogenous antibodies, or passive immunotherapy. In this review, we discuss the molecular-level strategies that researchers are using to design an effective therapeutic antibody, given the challenges in treating this disease. These challenges include selectively targeting a protein that has misfolded or is pathological rather than the more abundant, healthy protein, designing strategic constructs for immunizing an animal to raise an antibody that has the appropriate conformational selectivity to achieve this end, and clearing the pathological protein species before prion-like cell-to-cell spread of misfolded protein has irreparably damaged neurons, without invoking damaging inflammatory responses in the brain that naturally arise when the innate immune system is clearing foreign agents. The various solutions to these problems in current clinical trials will be discussed.