Mice bred to carry a gene variant found in a third of ALS patients have a faster disease progression and die sooner than mice with the standard genetic model of the disease, according to Penn State College of Medicine researchers. Understanding the molecular pathway of this accelerated model could lead to more successful drug trials for all ALS patients.

Amyotrophic lateral sclerosis, commonly known as Lou Gehrig’s disease, is a degeneration of lower and upper motor neurons in the brainstem, spinal cord and the motor cortex. The disease, which affects 12,000 Americans, leads to loss of muscle control. People with ALS typically die of respiratory failure when the muscles that control breathing fail.

Penn State researchers were the first to discover increased iron levels in the brains of some patients with the late-onset neurodegenerative disorders Parkinson’s disease and Alzheimer’s disease. A decade ago, they also identified a relationship between ALS and excess iron accumulation when they found that 30 percent of ALS patients in their clinic carried a variant of a gene known as HFE that is associated with iron overload disease.

For this study, the researchers crossbred mice with the HFE gene variant with the standard mice used in ALS research.

‘When we followed the disease progression and the behaviour of our crossbred mice compared to the standard mice, we saw significant differences,’ said James Connor, vice chair of neurosurgery research and director of the Center for Aging and Neurodegenerative Diseases. The crossbred mice performed significantly worse on tests of forelimb and hindlimb grip strength and had a 4 percent shorter life span.

‘The disease progression was much faster in the crossbred mice than in the standard mice,’ Connor said. ‘What we found is that when ALS happens in the presence of the HFE gene variant, things go downhill more quickly.’

The lead investigator on this project, graduate student Wint Nandar, noticed that the HFE gene variant sped up disease progression and death in females but not males. Males with ALS die faster, on average, than females.

Connor said the variant may not have had time to accelerate the pace of the disease in male mice. An accelerated progression may show up in clinical trials in human males, who live longer with the disease than mice.

The researchers also studied how the HFE gene modified the pace of the disease in mice. The crossbred mice showed increased oxidative stress and microglial activation. Microglial cells normally help with repair in the body, but when over-activated they can promote unhealthy inflammation.

‘They can make things worse instead of better,’ Connor said.

The mice were also found to have disruption of the neurofilaments, the tiny cables that transport nutrients through nerve cells.

 ‘It’s a much worse environment when the gene variant is present,’ Connor said. ‘This makes it much easier for the disease to take off.’

The findings could help direct more successful clinical testing of new drug treatments, which have traditionally had disappointing results. Because patients with H63D HFE have an accelerated form of the disease, their results could skew study findings.

‘There might be drugs out there that work for 70 percent of the ALS population even though the studies don’t show that when all of the data are looked at without consideration of the genetic background,’ Connor said.

Separating the data out could help find effective treatments for both those with the gene variant and the rest of the ALS population.

‘How a drug is going to work on a carrier of the gene variant could be worse or it could be better, but it’s likely going to be different,’ Connor said. Penn State

Damage to DNA is an issue for all cells, particularly in cancer, where the mechanisms that repair damage typically fail. The same agents that damage DNA also damage its sister molecule messenger RNA (mRNA), which ferries transcripts of the genes to the tens of thousands of ribosomes in each cell. But little attention has been paid to this damage.

 “There may be cases where messenger RNA is just as important as DNA,” said Carrie Simms, PhD, a postdoctoral associate in Zaher’s lab. “Clearly oxidative damage to RNA is somehow involved in neurodegenerative diseases, such as Alzheimer’s and ALS. It’s not necessarily causing the disease; it may just be some sort of by-product; but it’s in the mix.”

“Under normal conditions only about 1 percent of the cellular mRNAs are oxidized,” Zaher said, “but if you have oxidative stress, for whatever reason, a higher percentage can be damaged.

One of the hallmarks of Alzheimer’s is oxidative stress, and studies have shown that in people with advanced Alzheimer’s, half of the RNA molecules in the neurons may be oxidized.

Zaher, Simms and their colleagues report that when they fed oxidized mRNA to ribosomes, the nanomachines that convert mRNA to protein, the ribosomes jammed and stopped.

A stuck ribosome could be rescued by factors that released it from the mRNA and chewed up the damaged transcipt. But if the factors involved in this quality-control system were absent, damaged mRNA accumulated in the cell, just as it does in Alzheimer’s.

The three cellular processes essential to life—making copies of DNA, copying DNA into mRNA, and translating the mRNA into protein—have been penalized for billions of years by evolution, are astonishingly accurate, because evolution has heavily penalized any sloppiness.

Errors in DNA copying occur only once every billion events. When DNA is transcribed to mRNA, there is a mistake about once every ten thousand events .and when the mRNA is translated to protein, there might be an error once every thousand events.

To test the robustness of translation, the Zaher lab set out to break it, by giving faulty mRNA transcripts to ribosomes. They damaged one letter in a three-letter mRNA coding unit, oxidizing a G (the base guanine), to create what is called 8-oxo-G.

“We chose this oxidized base,” he said,” because we knew that when DNA is copied, an oxidized G causes a mistake. Instead of pairing with a C, as it normally would, 8-oxo-G will pair with an A.”

He thought the ribosome would read the three-letter codon C[8-oxo-G]C not as CGC but rather as CAC and conseqeuntly put the wrong amino acid in the protein chain it was making.

But when 8-oxo-G was added to a soup that contained all the factors needed to translate mRNA into protein, something surprising happened.

“We expected that we might get aberrant proteins,“ Simms said. “But the ribosome didn’t make mistakes.  It just stopped. It couldn’t deal with the mRNA at all”

The scientsts could tell it was stuck because levels of the protein the faulty mRNA encodes plummeted.

To make sure it was the presence rather than the position of the 8-oxo-G that mattered, Simms made mRNAs with the 8-oxo-G in each of the three positions of the three-letter coding unit. Each time the ribosome stalled.

Knowing they had found something interesting, the scientists upped their game. Simms built a longer 300-nucleotide mRNA to use as a probe. And instead of adding the damaged mRNA to a reconstituted bacterial system, she put it in extracts of plant and animal cells.

“We couldn’t look at ribosomes in the extracts,” Simms said, “but we could look at the proteins they made. They made short proteins, exactly the length you’d expect if the ribosome were stopping at the damaged base. “

A single mRNA typically has several ribosomes traveling along it, all simultaneously translating this transcript into protein. When the first ribosome stops, the others pile up behind it.

“You get this small product that is telling you the ribosome cannot go through the 8-oxo-G and then you get even smaller products that are telling you there are multiple ribosomes stuck behind the first ribosome. So the backed up ribosomes make a ladder of peptides,” Zaher said.

“This is a problem,” he said. “Among other things, the ribosome is an expensive machine that the cell has invested a lot of energy in making, and now it’s stuck on an mRNA. You need those ribosomes back.”

Fortunately ribosomes have three quality-control systems that keep watch for errors in the mRNA and rescue the ribosome if spot serious mistakes. One of these systems is “no-go decay.” When ribosomes are stuck and can’t go forward, they recruit factors that come in to pry open the ribosome, chew up the mRNA and add a tag to the defective peptide  that marks it for degradation.”

But no-go decay was originally discovered by throwing artificial roadblocks in the ribosome’s way: mRNAs with large hairpin turns in them that the ribosome could not unwind or plow through.

“Four billion years of evolution has made sure your genome does not have sequences that make hairpins, so these are clearly not the intended targets for no-go decay,” Zaher said.

To find out, the scientists turned to yeast cells. If the yeast’s ribosomes jammed on the oxidized mRNA but were rescued by no-go decay, very little damaged mRNA would accumulate in the cell. This proved to be the case.

Simms then deleted the gene for a factor that releases the ribosome from the mRNA when it jams. In these knockout yeast the level of oxidized mRNA went up. Then she deleted the gene for a factor that is recruited to degrade the mRNA after the ribosome is released, and again the level of oxidized mRNA rose. Without no-go decay, the cells were clearly in trouble.

“The system that translates mRNA into protein is highly conserved, so what’s true for yeast is probably true for people as well,” said Zaher. Washington University in St. Louis.

Tufts University School of Engineering researchers and collaborators from Texas A&M University have published the first research to use computational modelling to predict and identify the metabolic products of gastrointestinal (GI) tract microorganisms. Understanding these metabolic products, or metabolites, could influence how clinicians diagnose and treat GI diseases, as well as many other metabolic and neurological diseases increasingly associated with compromised GI function.

The human GI tract is colonized by billions of bacteria and other microorganisms, belonging to hundreds of species that are collectively termed ‘microbiota.’ Disruptions in the microbiota composition, and subsequently the metabolites derived from the microbiota, are increasingly correlated not only to GI diseases such as inflammatory bowel disease (IBD) and colitis, but also to insulin resistance and Type 2 diabetes.

‘There is increasing evidence that microbiota-derived metabolites play a significant role in modulating physiological functions of the gut,’ said Professor Kyongbum Lee, senior author on the paper and chair of the Department of Chemical and Biological Engineering in Tuft School of Engineering. ‘Emerging links between the GI tract microbiota and many other parts of the body, including the brain, suggest the tantalizing possibility to influence even cognition and behaviour through relatively benign interventions involving diets or probiotics.’

However, to date, only a handful of metabolites principally produced by microbiota—rather than the host organism itself—have been identified. Identifying microbiota-derived metabolites and understanding their effects on specific host functions could open up new avenues of basic and clinical research to develop safe, targeted therapies involving molecules that, by definition, constitute the natural chemical makeup of the host.

‘Current methods of identifying and quantifying these metabolites are unable to distinguish whether the metabolites are produced by the host or the microbiota,’ said Lee.

The newly reported approach models the microbiome as a single, complex network of reactions. By using computational algorithms for network analysis, virtual pathways can be constructed to determine possible metabolic products. Then, these products can be parsed into host-derived or microbiota-derived metabolites.

The research team focused on aromatic amino acids (AAAs) because their metabolites are involved in many of the more than 2,400 distinct reactions expressed in the microbiota as a whole.

‘In addition, we studied AAA-derived metabolites because AAAs can give rise to a variety of bioactive chemicals, such as salicylic acid, an anti-inflammatory compound, and serotonin, which is a neurotransmitter, obviously important in proper brain function,’ said Lee.

Work previously published in the Proceedings of the National Academy of Sciences from Lee’s collaborator Arul Jayaraman, professor in the Artie McFerrin Department of Chemical Engineering at Texas A&M University who holds a master’s from Tufts School of Engineering, had already demonstrated that indole, a bacterial metabolite derived from the aromatic amino acid tryptophan, caused an anti-inflammatory response in the gut and increased resistance to pathogen colonization that could lead to infection

The algorithmic model in the research published today predicted 49 different metabolites would appear as exclusive to the microbiota. In vivo tests on mice then confirmed the presence of more than half of the predicted metabolites, including two novel metabolites, which play a role in the pathways that regulate microbiota metabolism as well as host immune function.

Next steps for the team include identifying microbiota metabolites whose levels are either significantly elevated or depleted during diseases such as IBD or cancer, to find disease-specific markers and explore possible roles for these metabolites in disease progression.

‘Ultimately, the goal is to apply our models to arrive at a mechanistic understanding of the roles microbiota products may play in human physiology, and in turn, diagnose and treat disease,’ said Lee. ‘I think the potential for impact is immense.’ Tufts University

High blood pressure is a leading cause of death around the world, and its prevalence continues to rise. A study shows that a protein in the spleen called placental growth factor (PlGF) plays a critical role in activating a harmful immune response that leads to the onset of high blood pressure in mice. The findings pave the way for the development of more effective treatments for this common and deadly condition.

High blood pressure, also known as hypertension, affects more than 1 billion people worldwide and is a major risk factor for stroke, heart failure, and kidney diseases. Mounting evidence suggests that immune cells such as T cells contribute to the development of hypertension, but the underlying mechanisms have not been clear. Senior study author Giuseppe Lembo of IRCCS Neuromed and his team suspected that PlGF could be the missing link because it plays important roles in both the cardiovascular system and the immune system.

The researchers found support for this idea in the new study. Mice that were genetically engineered to lack PlGF did not develop hypertension after they were infused with angiotensin II–a hormone that normally increases blood pressure. These mice were also protected from hypertension-related heart and kidney damage, unlike genetically normal mice. Moreover, PlGF deficiency prevented T cells from leaving the spleen, entering the blood stream, and infiltrating the vessels and kidneys where hypertension was manifested. Additional experiments revealed that the nervous system controls levels of PlGF in the spleen, and PlGF in the spleen in turn is essential for the activation of T cells and the onset of hypertension.

‘In recent years, anti-PlGF monoclonal antibodies have been developed as a strategy to slow tumor growth and for age-related macular degeneration,’ says lead study author Daniela Carnevale. ‘The ongoing clinical trials testing humanized monoclonal antibodies directed to PlGF opens up the possibility of targeting it in hypertension too.’

‘There is a pressing need for new treatments to control and better target resistant hypertension,’ says Lembo. ‘PlGF is an appealing molecular therapeutic target because clinical tools to target this pathway already exist.’ EurekAlert

Latest figures by the International Diabetes Federation (IDF) have shown that an average 20% of the GCC population and nearly 19% of the UAE population now live with diabetes, with a marked increase in type II diagnoses. Coupled with this rise in disease prevalence, the Health Authority Abu Dhabi (HAAD) is forecasting nearly fourfold increase of healthcare cost for UAE nationals between 2010 and 2030. 
With the pancreas transplantation solution (that involves implanting a healthy pancreas, one that can produces insulin, into an insulin-dependent diabetic patient who is at risk of severe complications) being considered as a more accessible therapy for diabetic patients, the Arab Health Congress, running alongside Arab Health in January 2015 in Dubai, brings together leading practitioners in the field to discuss approaches to address the social and economic burden of the regional rising rate of the disease. 
Commenting on the potentially groundbreaking role of drug discovery and transplantation therapies ahead of his speech at the Arab Health Congress, Dr Mikel Prieto, Surgical Director of the Kidney and Pancreas Transplant Program and Paediatric Kidney Transplantation Medical Director of International Practice Operations at the Mayo Clinic said: “Pancreas transplantation has come of age in the 21st century. The results of this relatively rare type of transplant are outstanding with graft and patient survival rates well above 90 percent. This procedure represents an excellent option for the type of diabetic patients who have significant difficulty controlling their blood sugar or who have developed kidney disease as a consequence of their diabetes. Today, we can offer them a pancreas transplant or a combined pancreas and kidney transplant. This will free them from the need to inject themselves with insulin several times a day.”
World Diabetes Day, which took place on the 14^th of November, was also a reminder of the need for urgent action to fight against the disease in order to prevent the rate of diabetes in the Middle East from doubling in the next 20 years. The IDF estimates the adult population in the MENA region will increase from 375 million in 2013 to 584 million by 2035, with diabetes sufferers rising from 34.6 million to 67.9 million.

www.arabhealthonline.com