Diesel fumes react with cholesterol to clog up arteries, new research suggests.
Scientists found that sooty pollution from lorries, buses and taxis conspire with blood fats to trigger the changes that lead to heart disease.
Study leader Dr Andre Nel, from the David Geffen School of Medicine at the University of California in Los Angeles, said: ‘When you add one plus one, it normally totals two, but we found that adding diesel particles to cholesterol fats equals three. Their combination creates a dangerous synergy that wreaks cardiovascular havoc far beyond what’s caused by the diesel or cholesterol alone.’
The researchers investigated the interaction between diesel exhaust particles and the fatty molecules found in low-density lipoprotein (LDL), the ‘bad’ form of cholesterol.
Laboratory tests showed that the particles and fats worked in tandem to active genes that promote cellular inflammation.
Previous studies have shown that inflammation in blood vessels is a major risk factor for atherosclerosis, the build up of hard deposits which can block arteries.
The same genes were activated in high cholesterol mice exposed to the particles.
‘Exactly how air pollutants cause cardiovascular injury is poorly understood,’ said Dr Nel, whose findings appear in the online journal Genome Biology. ‘But we do know that these particles are coated with chemicals that damage tissue and cause inflammation of the nose and lungs. Vascular inflammation in turn leads to cholesterol deposits and clogged arteries, which can give rise to blood clots that trigger heart attack or stroke.’
The next step will be to convert the genetic response into a biomarker that allows doctors to evaluate the likely effect of air pollution on a person’s health.
Cathy Ross, cardiac nurse at the British Heart Foundation (BHF), said: ‘We already know that prolonged exposure to air pollution results in a small increase in risk of death from heart disease and stroke.
‘This study provides evidence that one reason for the increased risk may be because small particles from the air pollution reach the bloodstream, where they interact with lipids (fats), making them more likely to be trapped in the vessel wall, leading to fatty build up – called atherosclerosis. The BHF is funding research into this area to identify how risk may be reduced.
‘For most people, we know that everyday measures such as eating a healthy diet low in saturated fat, taking regular physical activity and giving up smoking will have more impact on reducing the risk of developing heart disease.
‘But, anyone with chronic lung disease or coronary heart disease should avoid staying outside for long periods when pollution levels are high.’
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