American biologists have deepened our understanding of how to relate herpes and Alzheimer’s disease: this time they infected with the herpes virus is a three-dimensional model of the brain tissue. It turned out that the model behaves the same as the tissue from the brains of patients with Alzheimer’s disease: the neurons degenerate, lose their electrical activity and acquire subsidiary cells. And while talking about that the virus causes the disease directly, it’s still early, it is now clear that they are firmly connected. Work published in the journal Science Advances.
Factors that increase the risk of developing Alzheimer’s disease, there are many — among them are not only older age and female gender, but also down syndrome, obesity, social passivity, and many others. But the immediate cause, which is responsible for the appearance of amyloid plaques in the brain, is still to allocate failed. A culprit often offer pathogens — for example, intestinal microbes or bacteria from the oral cavity. In addition to them, the culprit is sometimes called herpes virus. If these suspicions are confirmed, it would appear that risk almost all people on Earth — because from 70 to 90 percent of the population, according to various estimates, carry it without symptoms in nerve tissue.
Until now it was thought that the role of herpes in the development of Alzheimer’s disease in a purely mechanical , a viral particle serves as the center of crystallization around which the deformed aggregates of amyloid peptides. However, this is not enough to assume the virus is the cause of the disease, in the best case — mechanical catalyst. Therefore, a group of researchers from tufts University under the direction of David Kaplan (David Kaplan) undertook to find out how the herpes infection acts on the neurons and their microenvironment.
The researchers worked with three-dimensional model of nervous tissue, which is constructed on your own design. At the heart of it lay the skeleton from silk protein filled with collagen gel. The researchers populated the frame Neitralnyi induced stem cells — the fibroblasts, which are directly reprogrammable in precursors of nerve tissue. In culture, they spontaneously differentiate in neurons and in accessory cells of the neuroglia.
For a start, the authors tested how a regular, three-dimensional culture of induced cells responds to infection. Infected cells herpes virus-in different concentrations: the ratio of viral particles to number of cells was 0.01, 0.1 or 1. It turned out that the maximum concentration during the day, the virus infects all cells in the culture, but even in minimum it penetrates approximately every fifth cell. However, the consequences of this intrusion was different: the highest concentration of the virus caused the death of almost a quarter of the cells in culture, but if we use a lower concentration of 0.0001 viral particles to the cell, the neurons do not die, and merge with each other, forming a complex multi-core designs with spikes.