Multiple sclerosis (MS) is an autoimmune disease that affects the central nervous system, damaging the protective coating on the nerves and the nerves themselves over time. It currently affects 400,000 people in the United States and 2.5 million people worldwide.
Still, researchers don’t fully understand the causes of multiple sclerosis and MS relapses, which are thought to contribute to the progression of the disease. They know that upper respiratory infections in MS patients can increase the risk for relapse, but they are still working to better understand how that process works.
In a recent study from the University of Illinois, researchers investigated how upper respiratory infections trigger MS relapses. The team ran tests on a group of lab mice that are genetically prone to developing an autoimmune attack of the brain and spinal cord. The mice were exposed to influenza, and the research team looked at the changes in the brains of the mice.
Exposure to the flu did result in MS-like symptoms in the mice; however, the virus itself was not found in the brain. Upon further examination, the research team found an increase in glial activation in the brains of mice who were infected with the flu. Glia cells hold neurons in place, but they can also call immune cells, such as T cells, to the brain.
In people living with MS, T and B cells attack the spinal cord, optic nerve, and brain. Once there, the immune cells attack the protective coating on the nerves, which affects neurological functions. In the infected mice in this study, glial activation causes T cells (and other immune cells) to move from the blood to the brain. For now, the researchers think that this may be what triggers an MS relapse.
The team found that glia may be signaling to immune cells via molecules called chemokines. One specific chemokine, known as CX-CL5, was elevated in the brains of the mice with the flu. This chemokine is also found in the cerebral spinal fluid of people with MS during a relapse.
“If we can pinpoint what’s driving environmental factors such as infection to cause relapse, then maybe we can intervene when the patient has signs of sickness, like runny nose or fever,” said Andrew Steelman, senior author on the study and assistant professor in the Department of Animal Sciences, the Neuroscience Program, and the Division of Nutritional Sciences at the University of Illinois.
This study could be used as a starting point for the medical community to further research CX-CL5, with the hopes of developing a pharmaceutical treatment in the future.
To learn more about the symptoms of MS and current treatment options, visit “What is Multiple Sclerosis?” on our blog.
References
Blackmore, Stephen, et al. “Influenza infection triggers disease in a genetic model of experimental autoimmune encephalomyelitis.” Proceedings of the National Academy of Sciences 114. 30 (2016): PNAS. Web. 13 June 2017.
Pietrangelo, Ann, and Valencia Higuera. “Multiple Sclerosis by the Numbers: Facts, Statistics, and You.” Healthline. 24 March 2015.
“The Immune System in Multiple Sclerosis.” Genentech. 25 April 2017.
University of Illinois College of Agricultural, Consumer and Environmental Sciences (ACES). “One step closer in explaining MS relapse during upper respiratory infection.” ScienceDaily. ScienceDaily, 9 August 2017.
