Pollution damages lung immune function
Immune defenses decline with age, including those of the lungs, explaining the exacerbation of lung diseases and infections in the elderly. One hypothesis that could explain this phenomenon is the quasi-permanent and increasing exposure to pollution. An article recently published in Nature Medicine sought to clarify the link between lung function and pollution.
In this study, the lungs of 84 non-smoking or only occasionally smoking donors aged 11 to 93 years old were analyzed post-mortem. The scientists observed that with age, the pulmonary lymph nodes were increasingly loaded with pollution particles, rendering them unable to function efficiently. The impact of pollution was even visible to the naked eye as the lymph nodes of the young donors were beige, while those of the older donors were rather black. Lung lymph nodes are essential for filtering foreign substances that enter via the respiratory tract and contain a large number of immune cells. In particular, a decrease in phagocytosis by macrophages and in the levels of cytokines produced was demonstrated.
This study suggests that pollution could be a major cause of the increased susceptibility of the elderly to respiratory infections. This phenomenon was also highlighted during the COVID-19 pandemic, as several studies showed that increased exposure to air pollution was correlated with COVID-19 mortality rates. These results highlight the need to better understand this link and to take efficient measures to limit air pollution...