Multiple sclerosis, Italian researchers discover a possible onset mechanism for the disease

February 26, 2010

A non-pathogenic bacterium is capable to trigger an autoimmune disease similar to the multiple sclerosis in the mouse, the model animal which helps to explain how human diseases work. This is what a group of researchers from the Catholic University of Rome, led by Francesco Ria (Institute of General Pathology) and Giovanni Delogu (Institute of Microbiology), have explained for the first time in a recently published article on the Journal of Immunology.

Multiple sclerosis is a disease due to an inflammatory reaction provoked by the immune system. It causes the disruption of the coating of the nerve fibres in the .

"We do not know what causes ", explains Francesco Ria, immunologist of the Catholic University. "We know that there exist a genetic factor and an environmental factor, but we do not yet posses a satisfactory theory which can explain how exactly this environmental factor works".

Currently, there are two competing theories on the field: according to a first hypothesis, a virus hides within the brain and what causes the disease is the immunologic antiviral reaction. On the other hand, the second hypothesis states that a viral or bacterial pathogen similar to specific molecules of the Central Nervous System causes an inflammation which provokes a reaction of the immune system. This reaction ends up destroying the brain cells. The latter is called the autoimmune hypothesis.

This is the hypothesis that the researchers coming from the Institutes of General Pathology, Microbiology and Anatomy of the Catholic University of Rome have been testing with their two-year long work. To demonstrate the viability of this idea, scientists have fooled the mouse immune system, modifying subtly a bacterium of the common family of mycobacteria (the same family to which also the bacterium causing tuberculosis belongs) to make it look like to myelin, the protein coating nerve cells. This modified mycobacterium is completely innocuous. As all external agents, though, it is capable to trigger the reaction of the T-cells of the immune systems. They intervene to destroy it. Since they are innocuous bacteria, although very common in the environment, and since they induce an immune reaction, they are the ideal bacteria scientists can use to study the environmental factor contributing, together with the genetic factor, to cause multiple sclerosis.

"Normally, T-cells cannot penetrate into the Central Nervous System", adds Rea, "because the hematoencephalic barrier prevents them from doing so. But the bacterium modifies the characteristics of the T-cells and allows them to overcome the barrier. In 15 days the bacterium disappears completely from the body".

Yet these T-cells can now enter into the brain. This way, they begin to attack the myelin of the , and here is how the immune disease breaks out.

"We basically demonstrate - explains Rea - that in an animal model it is possible to be infected with something not carrying any disease, and later on develop a purely autoimmune disease".

Yet there is another element in this complex research, sponsored by the Italian Association of Multiple Sclerosis (AISM). "Normally - clarifies Rea - to understand which diseases we have encountered, we measure the antibodies produced by that specific pathogen. But there is a whole world of infectious agents which do not induce the production of antibodies, as is the case in our research: mycobacteria and many other bacteria produce a very low and variable number of antibodies. It is thus very hard to establish whether a population has encountered that specific infectious agent. So, we demonstrate that those infectious agents which are more likely to produce an autoimmune reaction are just those which do not induce antibody production".

Obviously, this is only the first step to better understand the way this very complex and devastating disease works. Ria and Delogu are not stopping here: "We want to try to understand the exact characteristics which this infectious agent should have", they explain. "Might it truly be a good experimental model for multiple sclerosis? If we had prolonged the action of the bacteria, would we have favoured or hampered the development of the disease? And what about the myelin-like bacterium protein: where should it lie? On the surface, or inside? These are all questions - conclude the two researchers - which we will be trying to answer in the next years, in the hope to defeat this terrible illness. We could even imagine to develop a vaccine by which we could prevent the immune response associated to multiple sclerosis".

Related Stories

Recommended for you

Researcher identifies a new way to treat HIV

August 24, 2017
Medical treatment that targets human proteins rather than ever-mutating viruses may one day help HIV-positive people whose bodies have built a resistance to "cocktails" currently used to keep them healthy, according to a ...

New insights into the world of trypanosomes

August 23, 2017
Single specimens of the vermicular pathogens causing sleeping sickness swim inside the gut of the tsetse fly between blood cells which the fly has ingested from an infected mammal. This is where they start their week-long ...

Survey of DNA fragments circulating in the blood suggests vast microbial diversity

August 23, 2017
A new survey of DNA fragments circulating in human blood suggests our bodies contain vastly more diverse microbes than anyone previously understood. What's more, the overwhelming majority of those microbes have never been ...

Study a breakthrough in understanding chronic pain in children

August 23, 2017
A University of Calgary psychologist who studies pediatric pain has made a breakthrough in understanding the cause of chronic pain in adolescents—by focusing on those recovering from major surgeries.

Scientists develop infection model for tickborne flaviviruses

August 22, 2017
National Institutes of Health (NIH) scientists have filled a research gap by developing a laboratory model to study ticks that transmit flaviviruses, such as Powassan virus. Powassan virus was implicated in the death of a ...

Zika virus stifles pregnant women's weakened immune system to harm baby, study finds

August 21, 2017
The Zika virus, linked to congenital birth defects and miscarriages, suppresses a pregnant woman's immune system, enabling the virus to spread and increasing the chances an unborn baby will be harmed, a Keck School of Medicine ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.