Sun. Feb 5th, 2023
Inhaled nanoparticles can clog our arteries and cause cardiovascular disease

Air pollution is a major cause of death. Researchers estimate that smog, especially the smallest particles in the mix, contribute to the early death of up to 7 million people worldwide each year. Damage to mist-filled lungs is an obvious concern, but air pollution is particularly linked to cardiovascular events, including heart attacks and strokes. And researchers have wondered why.

A leading theory is that the tiny particles can cause systemic inflammation and cellular stress that can affect the cardiovascular system and disrupt heart rhythms. But a new study suggests the nanoparticles play a more direct role in the disease.

In mice and humans, nanoparticles the size of air pollution slipped out of the lungs and into the bloodstream. There, they glossed over plaques in the arteries of both species, directly contributing to atherosclerosis and deadly cardiovascular disease, researchers report in an upcoming issue of ACS Nano.

The study, led by cardiovascular scientists from the University of Edinburgh, could help researchers better understand cardiovascular health and find ways to minimize the risks of air pollution. The findings could also help manufacturers develop safer products, as nanoparticles can now be tested in everything from electronics to medical devices and pharmaceuticals.

“These findings are of immediate relevance to the nanotechnology industry, where a wide variety of engineered nanomaterials are being developed for an increasing number of applications,” the authors write.

Animal data had hinted that nanoparticles could jump the barriers from in the lungs to ride into the bloodstream. But researchers didn’t know if that was also true for humans. For their new study, the authors recruited 14 healthy male volunteers to inhale gold nanoparticles of various sizes for two hours in a room where they also did moderate exercise on an exercise bike. The exercise got the participants to take a deep breath and get the nanoparticles deep into their lungs.

Gold rush

The gold nanoparticles were similar in size to those found in combustion exhaust, a major component of air pollution. The finest particles of air pollution can contain nitrogen oxides, sulfur dioxide and other toxic ingredients that can cause oxidative stress and inflammation in the body. Gold, on the other hand, is effectively inert.

The researchers took blood and urine samples from the volunteers during the first 24 hours after their exposure to gold, then again after three months. None of the volunteers had gold in their bloodstream before the experiment. But within 15 minutes, gold appeared in some participants. After 24 hours, 12 of the 14 had it in their blood. The participants who inhaled the tiniest nanoparticles — about 5 nanometers or less in diameter — had gold in their urine after 24 hours. The particles were still found in both blood and urine after three months.

The researchers then gave doses of gold nanoparticles to mice that had been genetically engineered to develop atherosclerosis (where plaque builds up in their arteries). The gold appeared in their livers and arteries. Most importantly, gold joined the plaques in the animals’ arteries, contributing to the blockage of blood flow.

To see if this happens in humans, the researchers recruited 12 patients who had scheduled surgery to remove plaques from their carotid arteries. Three of them agreed to inhale gold nanoparticles (5 nanometers in diameter) for four hours while resting for 24 hours before their surgery. The researchers detected gold in the blood of one patient and in the urine of the other two. All three had gold nanoparticles in the plaques removed from their arteries, while none of the other nine patients showed any signs of gold.

While the gold nanoparticles seemed to directly contribute to blockages, the authors fear that pollution nanoparticles could be even worse. Because those particles can be reactive and toxic, they can cause further inflammation and cellular stress when they clump together on the side of an artery, exacerbating the disease. And if the particles clump together at other sites of inflammation in the body, it could have implications for other diseases, such as cancer. It could also mean that babies could be exposed to nanoparticles during pregnancy.

“A better understanding of how nanoparticles move and accumulate at disease sites is of paramount importance for the risk assessment of both environmental and engineered nanoparticles,” the authors conclude.

ACS Nano2017. DOI: 10.1021/acsnano.6b08551 (About DOIs).

By akfire1

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