Research Roundup: Myelin and Age-Related Brain Deterioration and More

Brain

Every week there are numerous scientific studies published. Here’s a look at some of the more interesting ones.

Brain Wiring Insulation Tied to Age-Related Brain Deterioration

A study out of the University of Portsmouth identified the loss of myelin in the brain as a major factor in age-related brain deterioration. Myelin is protective insulation around the axons in the brain and is required for fast communication between nerve cells. The loss of myelin results in cognitive decline and is associated with multiple sclerosis (MS) and Alzheimer’s disease (AD). The study found that cells that drive myelin repair are less efficient as people age. The study was published in the journal Ageing Cell.

“A key feature of the ageing brain is the progressive loss of white matter and myelin, but the reasons behind these processes are largely unknown,” said Arthur Butt at the University of Portsmouth, who worked with Kasum Azim at the University of Dusseldorf in Germany and the research groups of Maria Pia Abbracchio in Milan and Andrea Rivera in Padua.

Butt added, “The brain cells that produce myelin—called oligodendrocytes—need to be replaced throughout life by stem cells called oligodendrocyte precursors. If this fails, then there is a loss of myelin and white matter, resulting in devastating effects on brain function and cognitive decline. An exciting new finding of our study is that we have uncovered one of the reasons that this process is slowed down in the aging brain.”

Ultimately, they identified GPR17, a gene associated to specific precursors. The loss of that gene is linked to a decreased ability of the precursors to actively replace the lost myelin.

Type 2 Diabetes Associated with Increased Risk of Parkinson’s Disease

A study out of Queen Mary University of London found convincing data that type 2 diabetes is associated with an increased risk of Parkinson’s disease. It also suggested that type 2 diabetes may speed disease progression in patients who already have Parkinson’s. It’s also possible that treating people with drugs for type 2 diabetes can decrease the risk and slow the progression of Parkinson’s. 

UK COVID-19 Strain Deadlier Than Other Strains

Although the new and emerging strains of COVID-19, specifically the South African, U.K. and Brazilian strains, all appear to be more infectious than the original Wuhan wildtype virus, the South African and Brazilian strains do not appear to be more deadly. However, data is starting to accumulate to support the theory that the U.K. strain, B117, is more lethal. A study published in the journal Nature suggest the U.K. strain may cause a 61% higher risk of 28-day mortality. Which is to say, the risk of dying from the U.K. strain at the 28-day mark is 61% more likely than if infected with other strains. This supports findings published last week in BMJ that found B117 had a 64% higher 28-day risk of death in people 30 years or older. It's important to note that both studies also observed that the 28-day mortality risk was low for most populations.

Environmental Information is Transmitted by Non-DNA Molecules in the Sperm

Scientists with McGill University made a significant discovery in the field of epigenetics by identifying how environmental information is transmitted in sperm by non-DNA molecules. Sperm basically remember a father’s environment, such as diet, and transmit that information to the embryo. They studied the sperm epigenome by feeding male mice a folate deficient diet and tracing the effects on particular molecules in proteins associated with DNA. This diet caused changes to methyl groups, which are a carbon atom with three hydrogen atoms attached, that are associated with histone proteins, which are involved in the structure and packaging of DNA into chromosomes and cells. The changes led to alterations in embryo gene expression that led to birth defects of the spine and skull. The changes to the methyl groups on the histones in sperm were transmitted at fertilization and remained in the developing embryo.

Sex Differences in Brain Diseases

Men and women are affected differently by brain diseases such as Alzheimer’s and Parkinson’s. Researchers at the University of Maryland separated cell data by sex which implicated differences in the blood-brain barrier between men and women, suggesting that the barrier can be stronger in women than men, and that they are built and behave differently. They believe this might explain at least some of the differences, such as Alzheimer’s being more prevalent in older women than men and men being impacted more frequently and usually more severely by Parkinson’s disease. The sex differences also would seem to apply to other brain diseases, such as multiple sclerosis, motor neuron disease, and others.

COVID-19 Virus Hijacks 2 Key Metabolic Pathways

Investigators from Brigham and Women's Hospital, Massachusetts General Hospital (MGH) and the Broad Institute identified two metabolic pathways that SARS-CoV-2, the virus that causes COVID-19, hijacks for self-replication. They found that the infected cells quickly depleted stores of glucose and folate. The virus diverts building blocks from glucose production to assemble purine bases that it needs to create huge amounts of viral RNA. They also found that that the 1-carbon pathway, which is used to metabolize folate, was hyperactive in infected cells. The virus hijacks that pathway to create more carbon for making bases for DNA and RNA.

The investigators note that drugs that inhibit folate metabolism, such as methotrexate, are used to treat autoimmune diseases like arthritis and could be potential treatments for COVID-19. Methotrexate is already being evaluated to treat the inflammation associated with advanced COVID-19 infections, but the investigators suggest it could be beneficial earlier on. However, methotrexate also suppresses the immune system, which would make its use as a prophylactic problematic.

“We’re hoping that, ultimately, we can find a way of preventing viruses from using cells’ metabolism pathways to replicate themselves because that could limit the ability of viruses to evolve resistance,” Benjamin Gewurz, of the Division of Infectious Disease and corresponding author.

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