Monday July 23, 2018

A Landmark Study Links Herpes 6 and 7 with Alzheimer’s Disease

The findings also showed multiple points of overlap between virus-host interactions and genes associated with Alzheimer's risk

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A Landmark Study Links Herpes 6 and 7 with Alzheimer's Disease
A Landmark Study Links Herpes 6 and 7 with Alzheimer's Disease. (IANS)
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Scientists have found up to two times higher level of human herpes virus among people with Alzheimer’s disease, suggesting the potential role of the viruses in the development of the progressive brain disorder.

Herpes virus causes contagious sores, most often around the mouth or on the genitals.

The study found unusually increased level of human herpesvirus named human herpesvirus 6A (HHV-6A) and human herpesvirus 7 (HHV-7 ) in the brains of the people with Alzheimer’s than those without the disorder.

“The hypothesis that viruses play a part in brain disease is not new, but this is the first study to provide strong evidence,” said Richard J. Hodes, Director from the US National Institutes of Health.

“Our work identified specific biological networks that offer new testable hypotheses regarding the role of microbial defense and innate immune function in the pathophysiology of Alzheimer’s,” said Joel Dudley from the Institute for Next Generation Healthcare at the Icahn School of Medicine at Mount Sinai.

alzheimers
Patient of Alzheimer’s. Pixabay

The findings also showed multiple points of overlap between virus-host interactions and genes associated with Alzheimer’s risk. Multiple viruses impact the biology of Alzheimer’s disease across domains such as DNA, RNA and proteins.

“If it becomes evident that specific viral species directly contribute to an individual’s risk of developing Alzheimer’s or their rate of progression once diagnosed, then this would offer a new conceptual framework for understanding the emergence and evolution of Alzheimer’s at individual, as well as population, levels,” Dudley explained.

In the study, published in the journal Neuron, the team initially performed RNA sequencing on four brain regions in more than 600 samples of postmortem tissue from people with and without Alzheimer’s to quantify which genes were present in the brain, and whether any were associated with the onset and progression of Alzheimer’s.

Also Read: Parkinson’s Identified Gene to Combat Alzheimer’s

Using different computational approaches, the team uncovered a complex network of unexpected associations, linking specific viruses with different aspects of Alzheimer’s biology.

They examined the influence of each virus on specific genes and proteins in brain cells, and identified associations between specific viruses and amyloid plaques, neurofibrillary tangles, and clinical dementia severity.

Further, they incorporated 800, RNA sequencing samples and observed a persistent increase of HHV-6A and HHV-7 in samples from individuals with Alzheimer’s. (IANS)

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Cholesterol Can Increase Risk of Alzheimer’s Disease, Finds Research

In the case of Alzheimer's disease, the amyloid-beta molecules stick to the lipid cell membranes that contain cholesterol.

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In Alzheimer's disease, patients start losing memory, Pixabay

Cholesterol — a molecule normally linked with cardiovascular diseases — may also play an important role in the onset and progression of Alzheimer’s disease, researchers have found.

The findings, published in the journal Nature Chemistry, suggests that in the brain, cholesterol acts as a catalyst which triggers the formation of the toxic clusters of the amyloid-beta protein, which is a central player in the development of Alzheimer’s disease.

The researchers found that cholesterol, which is one of the main components of cell walls in neurons, can trigger amyloid-beta molecules to aggregate, and their aggregation eventually leads to the formation of amyloid plaques, in a toxic chain reaction that leads to the death of brain cells.

“The levels of amyloid-beta normally found in the brain are about a thousand times lower than we require to observe it aggregating in the laboratory – so what happens in the brain to make it aggregate?” said lead author Michele Vendruscolo, Professor at Centre for Misfolding Diseases, in the University of Cambridge.

Cholesterol -- a molecule normally linked with cardiovascular diseases -- may also play an important role in the onset and progression of Alzheimer's disease, researchers have found.
Junk Food is highly rich in Cholesterol, pixabay

For the study, using a kinetic approach, the researchers found in vitro studies that the presence of cholesterol in cell membranes can act as a trigger for the aggregation of amyloid-beta.

Since amyloid-beta is normally present in such small quantities in the brain, the molecules don’t normally find each other and stick together. Amyloid-beta does attach itself to lipid molecules, however, which are sticky and insoluble, the researcher said.

In the case of Alzheimer’s disease, the amyloid-beta molecules stick to the lipid cell membranes that contain cholesterol.

Also Read: Small Head Blows Can Also Increase Risk of Dementia 

Once stuck close together on these cell membranes, the amyloid-beta molecules have a greater chance to come into contact with each other and start to aggregate – in fact, the researchers found that cholesterol speeds up the aggregation of amyloid-beta by a factor of 20.

“The question for us now is not how to eliminate cholesterol from the brain, but about how to control cholesterol’s role in Alzheimer’s disease through the regulation of its interaction with amyloid-beta,” Vendruscolo said.

“We’re not saying that cholesterol is the only trigger for the aggregation process, but it’s certainly one of them,” Vendruscolo added. (IANS)