Small Study Links Air Pollution to Increased Immune Activity in People with MS

Researchers from Italy report that increased levels of inhaled air pollutants were linked to increases in immune cell activity in people with MS, but not in people without the disease.

• Although the cause of multiple sclerosis, an immune-mediated disease, is not yet known, more is being learned about environmental and genetic factors that are related to the risk of developing this disease and factors that may increase disease activity. There is no single risk factor that provokes MS, but several factors are believed to contribute to the overall risk.
• There have been previous reports of a connection between air pollution and the prevalence of MS and it has also been linked to increased disease activity. In this small study researchers looked at measurements of “PM10” that were obtained from a regional air-quality monitoring network. PM stands for particulate matter, a mixture of solid particles (such as dust, dirt, or liquid droplets found in the air) that are inhalable.

• The team looked at PM10 measurements in the neighborhoods of 57 people with MS and 19 controls without MS. They compared pollution measurements with the activity of immune cells and immune messenger proteins seen in their blood samples. They also tested the effects of PM10 on immune cells in lab dishes.  
• The results showed that higher levels of PM10 were associated with higher levels of immune molecules that draw attacking cells into the nervous system, and molecules that heighten the abilities of these cells to increase inflammation. This immune reaction was found both in the participants’ circulating immune cells and also in lab dishes.
• The results warrant further research in larger numbers of people to confirm the findings and to help determine whether air pollution can worsen MS activity or even trigger the disease.  

“Air pollution as a contributor to the inflammatory activity of multiple sclerosis” by Andrea Cortese (University of Pavia, Pavia, Italy), Roberto Bergamaschi (IRCCS Mondino Foundation, Pavia, Italy) and colleagues is published in Journal of Neuroinflammation (2020; 17: 334).