Multiple sclerosis: this is how the immune system ‘nibbles’ on our neural connection

A few months ago, my internet connection started to give problems. And we already know what happens: we can be without water, food or heating, but not without internet. At first it was very slight: at times, the connection went slowly, then it returned to being normal and later broke again. As the days passed, the problem worsened, slowing down and losing connection for long periods of time. So no one can work, study, or watch a series!

The problem must be significant, since the technical staff has been lifting the sidewalk for days. Until one day the bad news arrives: “the breakdown is serious.” Apparently, an infestation of rats in the neighborhood has been nibbling on the wrapping that protects the optical fiber for some time. At first, it was just a little bit and that’s why the internet, even though it was slowing down, kept working. Until the rats finished with all the envelope and the communication was cut off completely.

Myelin: the friendly gesture of oligodendrocytes

Friendship is giving a friend the best you have. This is what oligodendrocytes must think, small cells that we have in the nervous system and that are great “friends” of neurons. So much so that they give everything for them.

Curiously, the first description in a scientific article that was made on oligodendrocytes was made by a Spaniard, Pio del Río Hortega, thanks to a new silver carbonate staining method that he himself designed. A year later, Del Río Hortega predicted that oligodendrocytes could be involved in myelination processes. And he was not wrong.

It is precisely this myelination that is the great sign of friendship between oligodendrocytes and neurons. Neurons are the cells of the nervous system responsible for transmitting information in the form of an electrical impulse.

This information travels through a prolongation of the neuron called an axon. And therein lies its importance, since thanks to the axon the information passes from one neuron to another, reaching all corners of the nervous system. In the same way that fiber optics brings us the internet home.

The axon is so important that the oligodendrocytes protect it during its journey, “hugging” it and forming a protective layer around it called myelin.

Myelin isolates the axon from everything that surrounds it, keeping it safe. But it also favors the transmission of information from one neuron to another, in the same way that the envelope that surrounds the optical fiber protects it, allowing the internet to reach our home quickly and efficiently.

Myelin sheath surrounding the neuronal axon in a healthy individual (left) and in a multiple sclerosis patient (right).
Shutterstock / BlueRingMedia

Confused immune system

But not everything is as beautiful as it seems. And it is that sometimes our immune system, like the rats with the optical fiber, destroys the myelin sheath that surrounds the axons.

But he doesn’t do it on purpose. The immune system is in charge of protecting our body from pathogens. And that is what happens, that the immune system mistakes myelin for “something” that wants to harm us and starts all its machinery to kill it. In this way, the myelin gradually disappears, leaving multiple scars (sclerosis) in its place.

When this happens, communication between neurons is interrupted and information does not reach the nervous system well, like the internet in our house. This is how a disease called multiple sclerosis appears.

Around 55,000 people in Spain suffer from the disease and its Day is celebrated on December 18. It is usually diagnosed between the ages of 20 and 40 and the prevalence is more than double in women than in men.

Genetics and environment, tandem of its development

So far, the cause that causes the immune system to attack myelin is unknown. Although it is true that there is a genetic component – more than 200 genes have been identified that can make a person more susceptible to developing the disease – multiple sclerosis is not an inherited disease. Science suggests that it is produced by a combination of genetic and environmental factors.

Environmental factors include certain viral infections (Epstein Barr virus), lifestyle (obesity), vitamin D, even latitude.

And it is that epidemiological studies show that this disease is less frequent in regions close to the equator, where the incidence of sunlight is higher. This is closely related to vitamin D. The less sunlight, the less vitamin D production and, therefore, a greater predisposition to suffer from the disease, as occurs in the Nordic countries.

Symptoms that make it difficult to diagnose

There is a lot of variability in terms of its symptoms. Just as each person is different, the clinical manifestations of sclerosis vary greatly between individuals and depend greatly on the area of ​​the nervous system affected.

However, there are common symptoms such as vision problems, fatigue, weakness, difficulty swallowing, imbalance, cognitive and coordination problems or dizziness.

These symptoms are common to many other pathologies, so the diagnosis is often not easy. In fact, this disease is not detected with a single test and a complete physical and neurological examination is necessary.

In this sense, thanks to magnetic resonance imaging we can “see” the central nervous system and detect those scars that occur as a result of the destruction of myelin.

In search of a cure

Currently there are several treatments for multiple sclerosis that, although they do not cure the disease, are designed to modify its course, reducing the lesions or scars of the myelin sheath and, therefore, avoiding the appearance and severity of some symptoms.

While technical personnel fix the fault with the internet and try to find out why rats have killed the fiber optic cabling, hundreds of laboratories around the world are investigating the causes of sclerosis trying to develop a treatment that protects myelin and prevents it from the immune system damages it.

Our internet always ends up coming back. Myelin, at the moment, no. For this reason, it is vitally important to continue supporting scientific research, especially financially. Because we have already seen it in this year that we are about to conclude: without science there is no future.

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