The Technion Researchers Find to NanoParticles may Threaten Heart

Nanoparticles, extremely tiny particles measured in billionths of a meter, are increasingly everywhere, and especially in biomedical products. Their toxicity has been researched in general terms, but now a team of Israeli scientists has for the first time found that exposure nanoparticles (NPs) of silicon dioxide (SiO2) can play a major role in the development of cardiovascular diseases when the NP cross tissue and cellular barriers and also find their way into the circulatory system. Their study is published in the December 2014 issue of Environmental Toxicology.

Prof. Michael Aviram
The research team was comprised of scientists from the Technion Rappaport Faculty of Medicine, Rambam Medical Center, and the Center of Excellence in Exposure Science and Environmental Health (TCEEH).

“Environmental exposure to nanoparticles is becoming unavoidable due to the rapid expansion of nanotechnology,” says the study’s lead author, Prof. Michael Aviram, of the Technion Faculty of Medicine, “This exposure may be especially chronic for those employed in research laboratories and in high tech industry where workers handle, manufacture, use and dispose of nanoparticles. Products that use silica-based nanoparticles for biomedical uses, such as various chips, drug or gene delivery and tracking, imaging, ultrasound therapy, and diagnostics, may also pose an increased cardiovascular risk for consumers as well.”

In this study, researchers exposed cultured laboratory mouse cells resembling the arterial wall cells to NPs of silicon dioxide and investigated the effects. SiO2 NPs are toxic to and have significant adverse effects on macrophages. a type of white blood cell that take up lipids, leading to atherosclerotic lesion development and its consequent cardiovascular events, such as heart attack or stroke. Macrophages accumulation in the arterial wall under atherogenic conditions such as high cholesterol, triglycerides, oxidative stress – are converted into lipids, or laden “foam cells” which, in turn, accelerate atherosclerosis development.

“Macrophage foam cells accumulation in the arterial wall are a key cell type in the development of atherosclerosis, which is an inflammatory disease” says co-author Dr. Lauren Petrick. “The aims of our study were to gain additional insight into the cardiovascular risk associated with silicon dioxide nanoparticle exposure and discover the mechanisms behind Si02’s induced atherogenic effects on macrophages. We also wanted to use nanoparticles as a model for ultrafine particle (UFP) exposure as cardiovascular disease risk factors.”

Both NPs and UFPs can be inhaled and induce negative biological effects. However, until this study, their effect on the development of atherosclerosis has been largely unknown. Here, researchers have discovered for the first time that the toxicity of silicon dioxide nanoparticles has a “significant and substantial effect on the accumulation of triglycerides in the macrophages,” at all exposure concentrations analyzed, and that they also “increase oxidative stress and toxicity.”

A recent update from the American Heart Association also suggested that “fine particles” in air pollution leads to elevated risk for cardiovascular diseases. However, more research was needed to examine the role of “ultrafine particles” (which are much smaller than “fine particles”) on atherosclerosis development and cardiovascular risk.

“The number of nano-based consumer products has risen a thousand fold in recent years, with an estimated world market of $3 trillion by the year 2020,” conclude the researchers. “This reality leads to increased human exposure and interaction of silica-based nanoparticles with biological systems. Because our research demonstrates a clear cardiovascular health risk associated with this trend, steps need to be taken to help ensure that potential health and environmental hazards are being addressed at the same time as the nanotechnology is being developed.

The Technion-Israel Institute of Technology is a major source of the innovation and brainpower that drives the Israeli economy, and a key to Israel’s renown as the world’s “Start-Up Nation.” Its three Nobel Prize winners exemplify academic excellence. Technion people, ideas and inventions make immeasurable contributions to the world including life-saving medicine, sustainable energy, computer science, water conservation and nanotechnology. The Joan and Irwin Jacobs Technion-Cornell Institute is a vital component of Cornell NYC Tech, and a model for graduate applied science education that is expected to transform New York City’s economy.

American Technion Society (ATS) donors provide critical support for the Technion—more than $1.95 billion since its inception in 1940. Based in New York City, the ATS and its network of chapters across the U.S. provide funds for scholarships, fellowships, faculty recruitment and chairs, research, buildings, laboratories, classrooms and dormitories, and more.

Source: ATS

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Novel approach to treating asthma: Neutralize the trigger

Current asthma treatments can alleviate wheezing, coughing and other symptoms felt by millions of Americans every year, but they don't get to the root cause of the condition. Now, for the first time, scientists are reporting a new approach to defeating asthma by targeting the trigger -- the allergen -- before it can spark an attack. They describe their new compound, which they tested on rats, in ACS' Journal of Medicinal Chemistry.

Clive Robinson and colleagues explain that to prevent many health problems, the ideal approach to treatment or prevention involves getting to the cause of a condition and targeting it directly. Asthma, which occurs when the immune system goes into overdrive affecting the airway in response to an otherwise harmless substance, has posed a challenge to this model. That's because it can be set off by different allergens or irritants. But recent studies suggest that the picture might not be as complicated as previously thought. 

Scientists have found that dust mites are one of the most important triggers of allergic asthma. So Robinson's team wanted to find a way to neutralize mite allergens.

The researchers identified a compound that binds to a major dust mite allergen and turned it into an inhalable powder. They tested it on rats and found that it significantly dampened the animals' immune response when they were exposed to a variety of allergens. This compound and other similar inhibitors could hail a new direction in asthma treatment, say the researchers.

The authors acknowledge funding from the Wellcome Trust.

Source: American Chemical Society

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ALS progression linked to increased protein instability

The new study provides evidence that proteins linked to more severe forms of ALS are less stable structurally and more prone to form clusters or aggregates. Mutants of the superoxide dismutase (SOD) protein formed long, rod-shaped aggregates (shown here as red lattice), compared to the compact folded structure of wild-type SOD (purple ribbons). Credit: Image courtesy of the Getzoff and Tainer labs, The Scripps Research Institute.

A new study by scientists from The Scripps Research Institute (TSRI), Lawrence Berkeley National Laboratory (Berkeley Lab) and other institutions suggests a cause of amyotrophic lateral sclerosis (ALS), also known as Lou Gehrig's disease.

"Our work supports a common theme whereby loss of protein stability leads to disease," said John A. Tainer, professor of structural biology at TSRI and senior scientist at Berkeley Lab, who shared senior authorship of the new research with TSRI Professor Elizabeth Getzoff.

Getzoff, Tainer and their colleagues, who focused on the effects of mutations to a gene coding for a protein called superoxide dismutase (SOD), report their findings this week in the online Early Edition of the Proceedings of the National Academy of Sciences. The study provides evidence that those proteins linked to more severe forms of the disease are less stable structurally and more prone to form clusters or aggregates.

"The suggestion here is that strategies for stabilizing SOD proteins could be useful in treating or preventing SOD-linked ALS," said Getzoff.

Striking in the Prime of Life

ALS is notorious for its ability to strike down people in the prime of life. It first leapt into public consciousness when it afflicted baseball star Lou Gehrig, who succumbed to the disease in 1941 at the age of only 38. Recently, the ALS Association's Ice Bucket Challenge has enhanced public awareness of the disease.

ALS kills by destroying muscle-controlling neurons, ultimately including those that control breathing. At any one time, about 10,000 Americans are living with the disease, according to new data from the Centers for Disease Control and Prevention, but it is almost always lethal within several years of the onset of symptoms.

SOD1 mutations, the most studied factors in ALS, are found in about a quarter of hereditary ALS cases and seven percent of ordinary "sporadic" ALS cases. SOD-linked ALS has nearly 200 variants, each associated with a distinct SOD1 mutation. Scientists still don't agree, though, on just how the dozens of different SOD1 mutations all lead to the same disease.

One feature that SOD1-linked forms of ALS do have in common is the appearance of SOD clusters or aggregates in affected motor neurons and their support cells. Aggregates of SOD with other proteins are also found in affected cells, even in ALS cases that are not linked to SOD1 mutations.

In 2003, based on their and others' studies of mutant SOD proteins, Tainer, Getzoff and their colleagues proposed the "framework destabilization" hypothesis. In this view, ALS-linked mutant SOD1 genes all code for structurally unstable forms of the SOD protein. 
Inevitably some of these unstable SOD proteins lose their normal folding enough to expose sticky elements that are normally kept hidden, and they begin to aggregate with one another, faster than neuronal cleanup systems can keep up -- and that accumulating SOD aggregation somehow triggers disease.

Faster Clumping, Worse Disease

In the new study, the Tainer and Getzoff laboratories and their collaborators used advanced biophysical methods to probe how different SOD1 gene mutations in a particular genetic ALS "hotspot" affect SOD protein stability.

To start, they examined how the aggregation dynamics of the best-studied mutant form of SOD, known as SOD G93A, differed from that of non-mutant, "wild-type" SOD. To do this, they developed a method for gradually inducing SOD aggregation, which was measured with an innovative structural imaging system called SAXS (small-angle X-ray scattering) at Berkeley Lab's SIBYLS beamline.

"We could detect differences between the two proteins even before we accelerated the aggregation process," said David S. Shin, a research scientist in Tainer's laboratories at Berkeley Lab and TSRI who continues structural work on SOD at Berkeley.

The G93A SOD aggregated more quickly than wild-type SOD, but more slowly than an SOD mutant called A4V that is associated with a more rapidly progressing form of ALS.

Subsequent experiments with G93A and five other G93 mutants (in which the amino acid glycine at position 93 on the protein is replaced with a different amino acid) revealed that the mutants formed long, rod-shaped aggregates, compared to the compact folded structure of wild-type SOD. The mutant SOD proteins that more quickly formed longer aggregates were again those that corresponded to more rapidly progressing forms of ALS.

What could explain these SOD mutants' diminished stability? Further tests focused on the role of a copper ion that is normally incorporated within the SOD structure and helps stabilize the protein. Using two other techniques, electron-spin resonance (ESR) spectroscopy and inductively coupled plasma mass spectrometry (ICP-MS), the researchers found that the G93-mutant SODs seemed normal in their ability to take up copper ions, but had a reduced ability to retain copper under mildly stressing conditions -- and this ability was lower for the SOD mutants associated with more severe ALS.

"There were indications that the mutant SODs are more flexible than wild-type SOD, and we think that explains their relative inability to retain the copper ions," said Ashley J. Pratt, the first author of the study, who was a student in the Getzoff laboratory and postdoctoral fellow with Tainer at Berkeley Lab.

Toward New Therapies

In short, the G93-mutant SODs appear to have looser, floppier structures that are more likely to drop their copper ions -- and thus are more likely to misfold and stick together in aggregates.

Along with other researchers in the field, Getzoff and Tainer suspect that deviant interactions of mutant SOD trigger inflammation and disrupt ordinary protein trafficking and disposal systems, stressing and ultimately killing affected neurons.

"Because mutant SODs get bent out of shape more easily," said Getzoff, "they don't hold and release their protein partners properly. By defining these defective partnerships, we can provide new targets for the development of drugs to treat ALS."

The researchers also plan to confirm the relationship between structural stability and ALS severity in other SOD mutants.

"If our hypothesis is correct," said Shin, "future therapies to treat SOD-linked ALS need not be tailored to each individual mutation -- they should be applicable to all of them."

Source: The Scripps Research Institute

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What bank voles can teach us about prion disease transmission and neurodegeneration

This image shows accumulation of misfolded, toxic prion protein (brown staining) in the brain of a transgenic mouse expressing bank vole PrP and challenged with human variant Creutzfeldt-Jakob disease (vCJD) prions. Credit: Image courtesy of Dr. Joel Watts

When cannibals ate brains of people who died from prion disease, many of them fell ill with the fatal neurodegenerative disease as well. Likewise, when cows were fed protein contaminated with bovine prions, many of them developed mad cow disease. On the other hand, transmission of prions between species, for example from cows, sheep, or deer to humans, is -- fortunately -- inefficient, and only a small proportion of exposed recipients become sick within their lifetimes.

A study published on April 3rd in PLOS Pathogens takes a close look at one exception to this rule: bank voles appear to lack a species barrier for prion transmission, and their universal susceptibility turns out to be both informative and useful for the development of strategies to prevent prion transmission.
Prions are misfolded, toxic versions of a protein called PrP, which in its normal form is present in all mammalian species that have been examined. Toxic prions are "infectious"; they can induce existing, properly folded PrP proteins to convert into the disease-associated prion form. Prion diseases are rare, but they share features with more common neurodegenerative diseases like Alzheimer's disease.

Trying to understand the unusual susceptibility of bank voles to prions from other species, Stanley Prusiner, Joel Watts, Kurt Giles and colleagues, from the University of California in San Francisco, USA, first tested whether the susceptibility is an intrinsic property of the voles' PrP, or whether other factors present in these rodents make them vulnerable.

The scientists introduced into mice the gene that codes for the normal bank vole prion protein, thereby generating mice that express bank vole PrP, but not mouse PrP. When these mice get older, some of them spontaneously develop neurologic illness, but in the younger ones the bank vole PrP is in its normal, benign folded state. The scientists then exposed young mice to toxic misfolded prions from 8 different species, including human, cattle, elk, sheep, and hamster.

They found that all of these foreign-species prions can cause prion disease in the transgenic mice, and that the disease develops often more rapidly than it does in bank voles. The latter is likely because the transgenic mice express higher levels of bank vole PrP than are naturally present in the voles.

The results show that the universal susceptibility of bank voles to cross-species prion transmission is an intrinsic property of bank vole PrP. Because the transgenic mice develop prion disease rapidly, the scientists propose that the mice will be useful tools in studying the processes by which toxic prions "convert" healthy PrP and thereby destroy the brain. And because that process is similar across many neurodegenerative diseases, better understanding prion disease development might have broader implications.

Source:  PLOS

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Targeted culling of deer controls disease with little effect on hunting

A new study found that the targeted culling of deer prevents the rampant spread of chronic wasting disease to healthy deer.

Chronic wasting disease, the deer-equivalent of mad cow disease, has crept across the U.S. landscape from west to east. It appeared first in captive mule deer in Colorado in the late 1960s. By 1981, it had escaped to the wild. It reached the Midwest by 2002. Little is known about its potential to infect humans.

The effort to keep chronic wasting disease in check in Illinois is a success, report researchers Nohra Mateus-Pinilla, left, a wildlife veterinary epidemiologist with the Illinois Natural History Survey; U. of I. animal sciences professor Jan Novakofski; and postdoctoral researcher Michelle Green.

Now researchers at the University of Illinois offer a first look at the long-term effectiveness of the practice of culling deer in areas affected by CWD to keep the disease in check. Their study appears in the journal Preventive Veterinary Medicine.

Each year, the Illinois Department of Natural Resources tests 7,000 (hunted, culled or incidentally killed) deer for CWD infection, conducts aerial surveillance to see where deer congregate and sends in sharpshooters to cull deer at the sites with disease, said Jan Novakofski, a professor of animal sciences at the University of Illinois and an author of the study.

"We know a lot about how far deer typically move," he said. "If they're sick, they're going to spread the disease that far. So if you find a deer that's sick, you draw that small circle and you shoot there."

Novakofski called this approach "a textbook scientific strategy for control. You reduce contact and you reduce the spread of infection with the smallest overall impact on healthy deer."

He and his colleagues at the Illinois Natural History Survey (part of the Prairie Research Institute at the U. of I.) found that the strategy worked: The prevalence of CWD in tested Illinois deer remained at about 1 percent from 2002 to 2012.

The team also found that hunters were killing more deer each year in each region of the state (north, central and south) regardless of CWD and CWD management. Statewide, the number of deer killed by hunters went from 147,830 in 2001, before the appearance of CWD, to 181,451 in 2012. The only exception: Two counties out of 10 with cases of CWD saw a reduction in hunter harvest over the same period.

"We wanted to know whether Illinois hunters have fewer deer to hunt now than they did before CWD," said Nohra Mateus-Pinilla, a wildlife veterinary epidemiologist at the INHS who led the study with postdoctoral researcher Mary Beth Manjerovic. "We found that hunter harvest has increased, and the prevalence of CWD has been maintained at low levels for 10 years in Illinois."

This finding answers a long-time complaint by some hunters that the culling of deer makes it harder for them to find deer to shoot, Novakofski said.
"Since 2001, hunter harvest of deer has increased similarly in the northern region of Illinois, where CWD occurs, and the rest of the state, where there is no disease or sharpshooting," he said.

In the two Illinois counties with fewer deer, "the reductions were 11 to 20 percent," Manjerovic said.

The team compared the Illinois experience with that of Wisconsin, which changed its CWD-management strategy from one that relied on culling to one that consisted primarily of allowing hunters to thin deer herds, the researchers said. Wisconsin saw a striking increase of infection in CWD-tested deer after it did that, the team found.

"In the early years in Wisconsin, (CWD prevalence) was still about 1 percent, just as it was in Illinois," Manjerovic said. "Then the strategy changed. Since 2007, CWD prevalence has increased to about 5 percent."

"We can't find an environmental or other variable that explains the increase in prevalence except a change in management," Novakofski said.

The numbers may not seem alarming to some, said postdoctoral researcher and co-author Michelle Green. But the trend is of concern, she said.

"CWD is a prion disease (like mad cow disease) and it's 100 percent fatal. 
There's no current way that we can actually make the deer better, so it's important that we keep it from spreading too far throughout the population," she said. "And then there's also the connection to mad cow disease. We don't have enough information yet to really understand what the impact to human health could be."

"We all hope that there is never a case of chronic wasting disease in humans. We all hope that it never spreads to people or agricultural animals," Novakofski said. "If it ever does, the investment in maintaining prevalence at a low level in Illinois will be repaid a thousand-fold."

Source: University of Illinois at Urbana-Champaign

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Scrapie could breach the species barrier

Scrapie is a neurodegenerative disease that has been known for centuries and which affects sheep and goats. Credit: INRA/Florent Giffard

INRA scientists have shown for the first time that the pathogens responsible for scrapie in small ruminants (prions) have the potential to convert the human prion protein from a healthy state to a pathological state. In mice models reproducing the human species barrier, this prion induces a disease similar to Creutzfeldt-Jakob disease. These primary results published in Nature Communications on 16 December 2014, stress the necessity to reassess the transmission of this disease to humans.

Scrapie is a neurodegenerative disease that has been known for centuries and which affects sheep and goats. Similar to Bovine Spongiform Encephalopathy (BSE) or mad cow disease, scrapie is caused by a transmissible pathogen protein called prion.

However, and contrary to BSE[1], epidemiological studies have never been able to establish a link between this disease and the occurrence of prion diseases in humans. "Risks of transmitting scrapie to humans (zoonose) were hitherto considered negligible because of the species barrier that naturally prevents prion propagation between species," said Olivier 

Andreoletti, INRA scientist who led the present study.

Researchers at INRA studied the permeability of the human transmission barrier to pathogens responsible for scrapie, using animal models specifically developed for this purpose. This approach previously allowed the confirmation of the zoonotic nature of prions responsible for BSE in cows and of the variant of Creutzfeldt-Jakob disease in humans (vCJD).

Unexpectedly, in these rodent models, certain pathogens responsible for scrapie were able to cross the transmission barrier. Moreover, the pathogens that propagated through this barrier were undistinguishable from the prions causing the sporadic form of Creutzfeldt-Jakob disease (sCJD). This data suggest a potential link between the occurrence of certain sCJD and these animal prions.

"Since CJD is scarce, about 1 case per million and per year, and incubation periods are usually long -several decades- it is extremely difficult for epidemiological studies to try and make this link," explains Olivier Andreoletti.

In their conclusions, the authors stress the fact that CJD cases are rare though scrapie has been circulating for centuries in small ruminants for which we eat the meat. Even if in future studies scrapie is finally confirmed to have a zoonotic potential, the authors consider that this disease does not constitute a new major risk for public health.

Source: INRA-France

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