Smoking is widely known to damage the lungs, but it also greatly increases the risk of heart attacks and strokes.
Scientists have long known that smokers are more likely to develop heart disease, yet exactly how cigarette smoke harms the blood vessels has remained unclear. A new study has now uncovered an important part of the answer.
Researchers at the University of Oklahoma found that cigarette smoke changes the way the immune system works. Their findings were published in the journal Circulation Research. The study suggests that smoking causes certain immune cells to trigger long-lasting inflammation that speeds up the formation of dangerous fatty plaques inside the arteries.
The team focused on neutrophils, the most common type of white blood cell. These cells are part of the body’s first line of defense and normally attack germs and help fight infections. In healthy people, they help protect the body without causing lasting damage.
When cigarette smoke enters the lungs, however, the researchers found that chemicals in the smoke overstimulate these immune cells. The neutrophils multiply quickly and move into blood vessels, where they interact with another type of immune cell called macrophages.
Macrophages normally act as the body’s cleanup crew. They remove dead cells and clear away excess cholesterol that can build up inside artery walls. This process helps keep blood vessels healthy and reduces the chance of blocked arteries.
The study showed that after neutrophils interact with macrophages, the neutrophils die and release inflammatory proteins called interleukin-1 alpha and interleukin-1 beta. These proteins interfere with the macrophages, making them much less effective at clearing harmful material from the arteries.
As damaged cells and cholesterol continue to build up, plaque becomes larger and more unstable. If a plaque breaks apart, it can create a blood clot that blocks blood flow to the heart or brain, leading to a heart attack or stroke. High blood pressure and other risk factors may increase this danger even further.
One surprising discovery was that cigarette chemicals produced similar immune changes even when they entered the body without being inhaled. This suggests that harmful tobacco chemicals can affect the immune system after they are absorbed into the bloodstream, not only through the lungs.
The researchers believe inflammation deserves as much attention as cholesterol in preventing cardiovascular disease. While quitting smoking remains the best way to reduce risk, understanding these inflammatory pathways may eventually lead to new medicines that better protect blood vessels.
The team now plans to identify which of the more than 7,000 chemicals in cigarette smoke are most responsible for these harmful effects. They also hope to study vaping products, nicotine pouches, and human volunteers to see whether the same immune response occurs.
Overall, this well-designed animal study reveals an important biological pathway linking smoking to heart disease, although human studies are still needed before the findings can be applied directly to patient care.
If you care about heart health, please read studies about top foods to love for a stronger heart, and why oranges may help fight obesity, diabetes, and heart disease.
For more health information, please see recent studies about simple guide to a 7-day diabetes meal plan, and why you should add black beans to your plate.
Source: University of Oklahoma.
