Infections trigger the immune system, responsible for fighting them. On the other hand, there is evidence that the innate immune system is involved in the onset of neurological lesions typical of multiple sclerosis (MS). That is why researchers at the Institut D’Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), along with researchers at the University of Southampton (Kingdom Clinical Neuroscience Unit and CNS Inflammation group), investigated if peripheral infections could worsen the prognosis of this disease in an experimental model with rats. The first author of the study published in Annals of Neurology is Dr. Beatriz Moreno, from the IDIBAPS’ group Pathogenetics and new therapies in MS.
The experiments were conducted with over 200 laboratory rats that were induced to a situation similar to the MS by injecting them an emulsion containing myelin basic protein. It triggers an activation of the immune system to neutralize the protein that entered the bloodstream which, consequently, also attacks the protein in the rat’s neurons generating an outbreak with neurological symptoms. After this outbreak the animals recovered without clinical complications. Later on, some of these animals were induced a situation similar to an infection by injecting them with a lipopolysaccharide, a molecule from the membrane of certain bacteria. To quantify the effects of the simulated infection on neurological tissue the spinal cord and brain of animals was analyzed.
Rats that had been exposed to infection after the outbreak of multiple sclerosis showed a significant worsening of neuronal damage. This study does not conclude that peripheral infections cause outbreaks associated with Multiple Sclerosis, as some researchers hypothesized. What the study demonstrates is that the infections worsen injuries in the central nervous system as a result of activation of the innate immune system. In diseases like Alzheimer’s similar effects have also been observed. Thus, although further research is needed, managing rigorously any kind of infection in patients with MS could help minimize the development of neurological damage.