Long-term exposure to air pollution can damage immune system
As we age, our health may gradually deteriorate. Our bodies age, wrinkles may form, metabolism may slow, and our immune system may weaken. However, much of what we consider to be natural aging may actually be due to preventable environmental factors.
A new study by researchers from Columbia University Irving Medical Center has found a strong link between exposure to air pollution and a weakening of the lungs' ability to battle respiratory infections. The findings shed light on why older people are particularly vulnerable to respiratory diseases such as COVID-19 and influenza, and serve as a reminder of the importance of clean air.
More than a decade ago, researchers began studying immune cells in lymphoid tissue from deceased donors. Their initial investigations uncovered something unexpected: lung lymph node tissue from non-smokers looked very different from lymph nodes in other parts of the body.
“When we looked at people’s lymph nodes, we were struck by how many of the nodes in the lung appeared black in color, while those in the GI tract and other areas of the body were the typical beige color,”
- Donna Farber, lead researcher on the project.
The researchers began to collect more lung lymph tissue from a variety of donors and quickly detected a pattern. The younger the lymph node, the lighter in color it was. And when the researchers took a closer look at the blackened lymph tissue, they found it was packed with air pollution particles.
A new study published in Nature Medicine set out to explore whether chronic exposure to air pollution could be damaging lymph nodes over time, impairing a person's immune response in the lungs. Lymph node tissue from both the lung and the gut were collected from 84 deceased donors spanning ages 11 to 93.
According to the study, polluting particles were found inside crucial immune cells in the lungs of older adults. This finding suggests that exposure to pollutants may have a significant impact on immune function as we age.
“These immune cells are simply choked with particulates and could not perform essential functions that help defend us against pathogens,”
Air pollution particles were found in immune cells called macrophages. These immune cells are like front-line soldiers in the lungs, destroying bacteria and sweeping away dead cells. Macrophages also act as crucial immune signaling cells, secreting molecules to call in reinforcements from other immune cells.
According to new findings, air pollution particles can accumulate in the lung nodes that produce macrophages, and this impairs their function. So over long periods of exposure to air pollution, our lungs ultimately decline in their ability to battle pathogens, leaving us more susceptible to respiratory infections.
While these findings are not intended to be a definitive explanation of how age makes us more vulnerable to diseases like influenza, the study provides robust evidence that decades of exposure to air pollution can weaken our immune defenses.
James Kiley, from the National Institutes of Health (NIH), said the findings are interesting and help us understand why the elderly are more susceptible to lung disease. Kiley, who didn't work on the study himself, also added that the study supports a greater push to address air pollution, something Farber and colleagues directly raise in the study.
"The specific effects of pollutants on lung inflammation and asthma in certain individuals or within certain geographic regions have been documented," the researchers concluded in the study. "The effects of pollutants on neurodegenerative disease are also well documented and neuroinflammation is implicated in this process. We therefore propose that policies to limit carbon emissions will not only improve the global climate, but also preserve our immune systems and their ability to protect against current and emerging pathogens and to maintain tissue health and integrity."
Source: New Atlas