Lungs surrounded by smoke: How does the immune defense line quietly collapse? 

The harm of smoking has long been a cliché. However, we still don’t have a deep enough understanding of how cigarette smoke erodes lung health step by step. It’s like we know that the enemy is powerful, but we don’t know what weapons they use and how they attack, so it’s naturally difficult to defend effectively. Recently, a study published in the Journal of Experimental Medicine (JEM) revealed the “secret weapon” behind the smoke, allowing us to more clearly understand the fatal blow of smoking to the lung immune system.

The Fall of MAIT Cells

However, researchers have found that harmful substances in cigarette smoke can actually “impersonate” bacterial signals, bind to MR1, and disrupt the normal operation of MAIT cells. This is like the enemy interfering with our radar system, making it impossible for the “special forces” to accurately receive instructions, or even “turning against us”, which in turn promotes the occurrence of inflammation.

The “invisible killer” in smoke: benzaldehyde derivatives

Cigarette smoke has a complex composition, containing more than 20,000 chemicals, and can be called a “chemical weapons arsenal.” Through computer simulation, researchers have locked on to some of these “invisible killers,” such as benzaldehyde derivatives. These substances can not only bind to MR1, but also change the number of MR1 on the cell surface, further interfering with the activation of MAIT cells. More worryingly, benzaldehyde derivatives are also used as flavorings for cigarettes and e-cigarettes, which means that even seemingly “harmless” e-cigarettes may cause damage to the lung immune system.

Experimental evidence: How smoking destroys the lungs step by step

To verify this finding, the researchers conducted a series of experiments. They found that cigarette smoke not only reduces the function of MAIT cells in human blood and experimental mice, but also causes mice to develop symptoms of lung disease. If they are infected with influenza at the same time, the symptoms will be more severe. Mice that have been exposed to cigarette smoke for a long time have a significantly reduced ability to resist influenza and are more likely to develop chronic obstructive pulmonary disease (COPD). More interestingly, the researchers found that mice lacking MAIT cells are less susceptible to cigarette smoke, have less lung inflammation, and less lung tissue damage. This further confirms that MAIT cells play an important role in smoking-induced lung damage.

COPD: The ultimate punishment for smoking

Chronic obstructive pulmonary disease (COPD) is a serious respiratory disease and the third leading cause of death worldwide. Smoking is one of the main causes of COPD. This study reveals how smoking exacerbates the occurrence and development of COPD by affecting MAIT cells. Smoking not only weakens the lungs’ ability to fight infection, but also promotes lung inflammation, accelerates the destruction of lung tissue, and ultimately leads to the occurrence of COPD.

Deep thinking: E-cigarettes are not safe either

This study not only reveals the harm of traditional cigarettes, but also rings the alarm bell for e-cigarettes. E-cigarettes also contain a variety of chemicals, including the benzaldehyde derivatives mentioned in the study. This means that even if you choose e-cigarettes, you cannot completely avoid damage to the lung immune system.

Protect your lungs by staying away from smoke

This study provides important scientific evidence for us to better understand the harm of smoking to lung health. It reminds us that the most effective way to protect lung health is to stay away from smoke, including active smoking and passive inhalation of second-hand and third-hand smoke. For the health of yourself and your family, please quit smoking as soon as possible and stay away from tobacco environments.