Early Parkinson’s Detection Technique Validated in Prion Animal Models, Study Shows

Parkinson's and IL-17A

The early detection of diseases characterized by protein misfolding and aggregation, such as Parkinson’s disease, moved one step closer by the validation in animal models of a sensitive technique to capture and analyze misfolded and aggregated proteins in the blood quickly and efficiently.

The technique was validated by showing that prions — a misfolded protein that causes prion disease — can be captured, isolated, analyzed, and transferred between species, a study has shown. 

The study, “Enhanced detection of prion infectivity from blood by preanalytical enrichment with peptoid-conjugated beads,” was published in the journal PLOS ONE

Parkinson’s disease is caused by the damage or death of dopamine-producing nerve cells (neurons) in a region of the brain that controls balance and movement. 

A hallmark of the disease is the accumulation of a misfolded form of a protein called alpha-synuclein, a protein typically located near the tips of nerve cells and associated with the regulation of dopamine release.

To function properly, a protein must fold into a specific shape. However, when alpha-synuclein does not fold properly or misfolds, it clumps together to form plaques in the brain, causing cell damage and death. 

A misfolded protein is also the causative agent in transmissible spongiform encephalopathies or prion diseases. The most famous prion disease is bovine spongiform encephalopathy (BSE) — otherwise known as “mad cow disease” — where misfolded proteins, called prions, from cows in the food chain or infected people trigger other proteins in the brain to misfold and aggregate. 

The outbreak of BSE in European cattle and several hundred associated cases in humans in the late 1980s has spawned efforts to find methods to detect the very low levels of prions in the blood of infected people.

One method that has been successful, called the misfolded protein assay (MPA), involved selectively capturing prions using molecules that mimic the parts of the prion that bind together to form aggregates.

These mimicking molecules — known as peptoids — are composed of modified versions of the naturally occurring amino acids (building blocks) of prion proteins.

The peptoids are fixed to magnetic beads (PSR1) which can be mixed, then easily isolated from blood and tested for prions. One of the advantages of MPA over other tests is that it can analyze large numbers of samples quickly and for less cost.

The MPA technique was used to successfully identify prions in a patient with prion disease when other tests failed. In addition, the utility to capture and analyze prions extends beyond prion diseases to other conditions characterized by protein misfolding, such as Parkinson’s, and may provide a means to diagnose the disease years before symptoms arise.

Before MPA can be used in humans, efficacy must be determined in animal models, so researchers designed a study to test the reliability and sensitively of MPA to detect prions using mouse and hamster models of prion disease.

Brain tissue from hamsters bred to develop prion disease was injected into 40 healthy hamsters, and five control hamsters were inoculated with brain tissue from non-infectious hamsters. 

Blood was withdrawn from the hamsters before and after the appearance of prion disease symptoms, namely ataxia (lack of muscle control), loss of appetite, and poor grooming. 

The PSR1 magnetic beads were mixed with these blood samples and were washed to remove extra proteins. The washed beads were then injected into a special breed of mice — Tg(SHaPrP) — that expressed the normal form of hamster prion protein. If infectious misfolded prions were captured by the beads, they would trigger the normal form of hamster prion protein to misfold in the mice and lead to prion disease. 

The results demonstrated that in mice that were inoculated with beads mixed with blood from hamsters with prion disease symptoms, nearly all of the mice (25 of 28 injected) developed prion disease. Prion disease was confirmed by examining mice brain tissue under a microscope. 

In contrast, mice injected with beads mixed with non-symptomatic hamster blood (or controls) did not develop signs of prion disease. 

“We therefore conclude that PSR1 beads highly efficiently capture prion infectivity from plasma from presymptomatic and symptomatic cases and are able to transmit infectivity to Tg(SHaPrP) mice,” the researchers wrote. “We found that the readout of the peptoid-based misfolded protein assay (MPA) correlates closely with prion infectivity in vivo, thereby validating the MPA as a simple, quantitative, and sensitive surrogate indicator of the presence of prions.” 

Ronald Zuckermann, PhD, study co-author and senior scientist at the Lawrence Berkeley National Laboratory Molecular Foundry, in Berkeley, California, noted in a news release, “Our peptoid beads have the ability to detect the misfolded proteins that act as infectious agents, so it could have a significant impact in the realm of prion diseases, but we have also shown that it can seek out the large aggregated proteins that are the disease agents in Alzheimer’s and Parkinson’s diseases, among others.” 

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Approved Blood Pressure Medication Also May Treat Parkinson’s Disease, Animal Study Suggests

Felodipine for Parkinson's

Felodipine, an approved therapy for high blood pressure, is able to promote the clearance of toxic protein aggregates in mouse models of neurodegenerative diseases, including Parkinson’s, according to a study.

The study, “Felodipine induces autophagy in mouse brains with pharmacokinetics amenable to repurposing,” was published in the journal Nature Communications.

A common feature of most neurodegenerative diseases, such as Alzheimer’s, Parkinson’s, and Huntington’s diseases, is the accumulation of toxic protein aggregates within neurons, or brain cells. Buildup of these proteins damages the cells and leads to neurodegeneration in these disorders.

Toxic material is normally cleared from the body through a mechanism called autophagy, which refers to the process by which cells degrade and purge unwanted material, such as harmful protein clusters.

Because autophagy often is impaired in neurodegenerative diseases, researchers are interested in identifying chemical compounds that can stimulate this process and potentially improve the clearance of toxic aggregates and reduce disease symptoms. However, no such treatment exists yet.

One possibility is to identify an existing medication that can be used for this purpose. Therapeutic compounds frequently have multiple targets, which means the same therapy often can treat different conditions. It is typically easier and faster to repurpose existing therapies because they already have gone through clinical trials and been found safe for human use.

To try to find one of these medications that might induce autophagy and be suitable for treating neurodegenerative diseases, researchers at the UK Dementia Research Institute and the University of Cambridge screened several different therapies that were approved for other indications.

They previously had identified an approved medication for high blood pressure and angina known as verapamil (sold under the brand names Calan, Covera, and Verelan, among others) as a powerful inducer of autophagy. However, it does not cross the blood-brain barrier (a thin membrane that protects the central nervous system, including the brain) and is therefore not appropriate for the treatment of neurodegenerative diseases.

The researchers then screened a panel of similar therapies to identify any that actually would penetrate the blood-brain barrier and have strong autophagy-inducing effects. This led them to felodipine as the most suitable candidate.

Felodipine (sold under the brand name Plendil) is approved by the U.S. Food and Drug Administration for the treatment of hypertension (high blood pressure). Laboratory studies indicated that felodipine promotes autophagy and clears a variety of toxic protein aggregates found in neurodegenerative diseases.

To further investigate felodipine, researchers tested the effects of the compound in animal models of Huntington’s and Parkinson’s diseases.

They performed a pharmacokinetic analysis to determine the optimal treatment regimen in mice that would mimic the concentration the therapy reaches in humans at currently prescribed doses. (Pharmacokinetics refers to how a compound is absorbed, distributed, metabolized, and excreted in the body.)

Results indicated that felodipine was effective at reducing the buildup of aggregates in mice with the Huntington’s and Parkinson’s disease mutations, as well as in a zebrafish model of dementia. Furthermore, long-term treatment with felodipine was associated with a decrease in signs of the diseases.

Notably, these effects were observed at concentrations of felodipine that would be safe for humans.

“These data suggest that this drug may have efficacy in humans with appropriate neurodegenerative diseases that may be ameliorated by autophagy induction,” the authors wrote.

“This is the first time that we’re aware of that a study has shown that an approved drug can slow the build-up of harmful proteins in the brains of mice using doses aiming to mimic the concentrations of the drug seen in humans,” David Rubinsztein, PhD, said in a press release. Rubinsztein, a professor of molecular neurogenetics at Cambridge, led the study. “As a result, the drug was able to slow down progression of these potentially devastating conditions and so we believe it should be trialled in patients.

“This is only the first stage, though. The drug will need to be tested in patients to see if it has the same effects in humans as it does in mice. We need to be cautious, but I would like to say we can be cautiously optimistic,” he said.

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Certain Compounds in Coffee, But Not Caffeine, Seen to Prevent Protein Buildup Linked to Parkinson’s in Early Study

coffee consumption

Chemical compounds in coffee — especially phenylindanes that form during the roasting of coffee beans — appear to prevent the damaging aggregation of amyloid-beta and tau known to play key roles in Parkinson’s and Alzheimer’s disease, researchers report.

Caffeine, in contrast, had no effect on protein buildup in this early lab study, and researchers saw coffee consumption to offer no protection against alpha-synuclein aggregation.

The study, “Phenylindanes in Brewed Coffee Inhibit Amyloid-Beta and Tau Aggregation,” was published in Frontiers in Neuroscience.

Coffee consumption has been suggested to reduce the risk of developing diabetes, various cancers, and neurodegenerative disorders such as Parkinson’s and Alzheimer’s disease. Despite the available evidence, however, it’s unclear what how exactly coffee can help to prevent age-related cognitive decline.

Past studies have reported that caffeine, the main bioactive compound of coffee, can reduce the risk of Parkinson’s both in men and in women who were not taking hormone replacement therapy. It has also been seen to reduce nerve cell death in the substantia nigra – the brain area most affected in Parkinson’s – in mouse models of the disease.

However, recent data also suggests that long-term consumption of caffeine may exacerbate anxiety-related behavioral and psychological symptoms in patients with dementia, counteracting its potential beneficial effects.

These contrasting findings highlight the need to identify those coffee components that may be neuroprotective.

Researchers led by Donald Weaver, MD, PhD, co-director of the Krembil Brain Institute, evaluated the potential of chemical components of coffee to inhibit the buildup of proteins that can drive neurodegenerative diseases like Alzheimer’s and Parkinson’s, in particular: amyloid-beta, tau, and alpha-synuclein.

The team started by examining three types of instant coffees — light roast, dark roast, and decaffeinated dark roast — in terms of their ability to prevent protein aggregates. They tested the instant coffees by adding them to one of these three proteins in an in vitro (laboratory dish) context.

“The effect of caffeine content would be assessed by comparing the activity of caffeinated and decaffeinated dark roast coffee extracts. Further, since it is known that different levels of roasting affect the composition of the coffee brew, comparison of light versus dark roast coffee extracts was also performed,” the researchers wrote.

Dark roast coffee showed the greatest inhibitory effect against tau protein buildup. Interestingly, the level of caffeine in each type of coffee had no impact on tau, amyloid-beta, and alpha-synuclein’s ability to aggregate.

“We were surprised to find that caffeine content did not influence aggregation inhibition, and thus performed a post-hoc analysis of pure caffeine,” the researchers said in the study. “No effect on fibril growth was observed relative to the vehicle control, consistent with the results for caffeinated versus decaffeinated coffee extracts.”

Further experiments found that all coffee extracts could prevent amyloid-beta and tau protein aggregation at 200 μg/mL concentration. Dark roast coffee (with or without caffeine) was seen as more potent in preventing the oligomerization — a chemical form that proteins can take — of amyloid-beta than the light roast extract.

All types of coffee as an instant mix, however, showed an ability to promote alpha-synuclein aggregation at amounts above 100 mg/mL.

To better understand these findings, the team then explored the activity of the six main chemical components of coffee — caffeine, chlorogenic acid, quinic acid, caffeic acid, quercetin, and phenylindane.

Researchers found that most of these compounds — with exception of caffeine and quinic acid for amyloid-beta, and caffeine and caffeic acid for tau — prevented protein aggregation.

Phenylindane was found to hold the strongest inhibitory activity, working as a dual-inhibitor to prevent the formation of amyloid-beta aggregates by 99% and those of tau tangles by 95.2%. Importantly, in later experiments, phenylindanes did not show “pro-aggregation behavior” toward alpha-synuclein, the study reported.

Phenylindanes are formed during the roasting of coffee beans and are found in higher concentrations in dark roast coffees, which have longer roasting times.

“It’s the first time anybody’s investigated how phenylindanes interact with the proteins that are responsible for Alzheimer’s and Parkinson’s,” Ross Mancini, a research fellow in medicinal chemistry at the Krembil institute and the study’s first author, said in a news release.  “The next step would be to investigate how beneficial these compounds are, and whether they have the ability to enter the bloodstream, or cross the blood-brain barrier.”

The team is now investigating if phenylindanes can reduce amyloid-beta, tau and alpha-synuclein loads in cell and animal models of Alzheimer’s and Parkinson’s disease.

Researchers caution that their findings are not recommendation for excessive coffee consumption.

“What this study does is take the epidemiological evidence and try to refine it and to demonstrate that there are indeed components within coffee that are beneficial to warding off cognitive decline,” Weaver said. “It’s interesting, but are we suggesting that coffee is a cure? Absolutely not.”

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Nanobodies Could Prevent Alpha-Synuclein’s Toxic Effects in Parkinson’s, Rat Study Suggests

Nanobodies alpha-synuclein

Antibody fragments, known as nanobodies, may be an efficient strategy to reduce abnormal alpha-synuclein protein aggregates and preserve motor function in Parkinson’s disease and other neurodegenerative disorders, a rat study suggests.

The study, “Proteasome-targeted nanobodies alleviate pathology and functional decline in an α-synuclein-based Parkinson’s disease model,” was published in the journal npj Parkinson’s Disease.

Parkinson’s disease belongs to a class of neurodegenerative disorders called synucleinopathies, characterized by the accumulation of misfolded alpha-synuclein aggregates. These abnormal protein aggregates are toxic to brain cells, triggering several damaging processes that promote the impairment and death of cells.

Given the key role of alpha-synuclein in the development and progression of Parkinson’s disease, many efforts have been made to find ways to effectively prevent its toxicity.

A team led by researchers at Rush University Medical Center in Chicago have developed a new strategy to target alpha-synuclein using nanobodies, small fragments of antibodies that can target and bind to specific proteins, tagging them for destruction.

In a previous study, the team showed that two particular nanobodies, called VH14 (also known as NAC14) and NbSyn87, could affect alpha-synuclein’s ability to aggregate. In the current study, they explored these nanobodies’ potential to prevent the progression of Parkinson’s in rats.

The team used an adenovirus-based system to deliver each nanobody directly into the substantia nigra — an area of the brain highly affected in Parkinson’s — of rats with Parkinson’s disease. This treatment was selectively administered to one side of the brain, or hemisphere, but not the other. An adenovirus is an inactivated virus that is very stable and easy to produce and can act as a “shell” to transport molecules inside cells. They are widely used for gene therapy purposes.

Treating the rats with either VH14 or NbSyn87 led to a nearly twofold reduction of the relative amount of toxic protein aggregates, compared with rats treated with a placebo. Notably, the nanobodies did not promote excessive destruction of alpha-synuclein, allowing residual protein activity to be maintained and preventing total loss of function.

Further detailed analysis revealed that rats treated with VH14 had 49% increased innervation in the striatum, compared with placebo-treated animals, and a 38% increase, compared with NbSyn87-treated rats. The striatum is a brain region involved in motor and reward systems, which receives dopamine inputs from different sources.

In addition, VH14 showed greater potential to protect the nerve cells in the substantia nigra from damage, whereas NbSyn87 showed just modest neuroprotective potential.

Evaluation of dopamine levels in the striatum region failed to show significant improvements upon treatment with either nanobody. Still, when comparing the treated versus non-treated brain hemispheres, animals treated with VH14 had about three times higher levels of dopamine, compared with placebo-treated rats.

Despite the variable impact on dopamine output, researchers reported that animals treated with VH14 had significant improvements in motor function over placebo-treated rats, restoring their walking ability and balance. Treatment with NbSyn87 also appeared to have a positive impact on preserving the animals’ motor function, but at a slower rate than VH14.

According to the researchers, these results demonstrate the “therapeutic efficacy of vector-delivered intracellular nanobodies targeting alpha-synuclein misfolding and aggregation in synucleinopathies such as Parkinson’s disease.”

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Source: Parkinson's News Today

Gene Found that Regulates Protein Aggregates in Neurodegenerative Diseases

ANKRD16 protein aggregates

A gene called Ankrd16 can prevent the harmful protein aggregates that build up in neurological disorders, including Parkinson’s disease, according to researchers.

Their study, “ANKRD16 prevents neuron loss caused by an editing-defective tRNA synthetase,” published in the journal Nature, adds a new layer of knowledge about the underlying mechanisms involved in toxic protein aggregates, contributing to the understanding of neurodegenerative diseases.

Scientists have known that an accumulation of abnormal protein aggregates in the brain is key to the development and progression of several neurodegenerative diseases. But what causes this protein malfunction has been unclear.

University of California San Diego researchers led by Susan Ackerman, PhD, previously found that the cellular machinery responsible for translating genes into functional proteins could in part be responsible for this process.

This process serves as the editorial team of a newspaper: It carefully proofreads and controls the process of transforming the information contained within genes into functional proteins.

Small editing mistakes result in the incorrect insertion of  a serine amino acid — the building blocks of proteins — into newly produced proteins, leading to “sticky” versions of proteins that will ultimately form toxic aggregates.

Specific cells in the cerebellum — a part brain of the brain that helps control movement and body balance — known as Purkinje cells are particularly sensitive to this disrupted process.

The research team has now found that the Ankrd16 gene is an important “proofreader” throughout this process and can prevent the faulty insertion of serine into protein sequences.

“Simplified, you may think of Ankrd16 as acting like a sponge or a ‘failsafe’ that captures incorrectly activated serine and prevents this amino acid from being improperly incorporated into proteins, which is particularly helpful when the ability of nerve cells to proofread and correct mistakes declines,” Ackerman said in a UC San Diego news story written by Mario Aguilera.

Purkinje cells normally have low Ankrd16 levels, which may explain why these nerve cells are more vulnerable to proofreading defects.

Increasing the levels of Ankrd16 in Purkinje cells from mouse models protected these cells from dying, while removing the gene led to an abnormal buildup of proteins and eventually cell death.

The researchers described Ankrd16 as “a new layer of the machinery that is essential to the prevention of severe pathologies that arise from defects in editing.”

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Source: Parkinson's News Today