Scientists are never short of new hypotheses about the cause and even the nature of diseases. For example, some of them now believe that “inflammation” is the underlying cause of many neurodegenerative diseases.
The human immune system is made up of different subsets of extreme complexity. The main mode of action is quite brutal, as the cells renew themselves quite quickly (from a few days to a few weeks), any slightly suspicious cell is deliberately killed by one of the agents of the immune system.
The central nervous system is composed of cells that have a probable lifespan of a hundred years or more, and they do not renew themselves through division, so this mode of operation is impossible. Therefore the central nervous system is kept isolated from the rest of the body through the blood-brain barrier and it has its own immune system.
Breaks in this barrier and the invasion of the CNS by the body's immune cells have sometimes been suggested as being able to cause diseases such as ALS, and now Alzheimer's.
A new article aims to show that in the case of Zika viruses, the terrible consequences that an infection causes are not due to the infection of cells by the virus, but by the invasion of the CNS by immune cells from the rest of the body.
The article incriminates CD8+ T cells which function like NK cells, formidable killers.
Antibody depletion of CD8 or blockade of NKG2D prevented ZIKV-associated paralysis.
Of course, this article is based on an experiment with mouse models of a disease, so it is quite risky to draw conclusions for humans.
In any case, once the damage is done, it is too late, as the neurons do not reproduce. Yet it is possible to have a form of damage mitigation, either thanks to neurogenesis in certain rare cases, or even to a sort of mutual aid mechanism between neurons, which causes a surviving neuron to try to take over the work of the dead neurons. This is what causes us to become clumsy as we age.
Therapy is therefore not to be expected quickly, the best is to maintain a healthy blood-brain barrier, that is to say, to follow the precautions recommended for cardiovascular diseases.