Vehicle Emissions Have An Effect On Cholesterol
May 16, 2013

Vehicle Emissions Have An Effect On Cholesterol

Michael Harper for — Your Universe Online

Emissions from car and truck exhaust have already been proven to have negative and lasting effects on the earth´s atmosphere and our overall environment. This week, academic researchers are suggesting the same emissions could have direct negative effects on human beings, transforming the “good” cholesterol in our bodies to bad. Bad cholesterol has been linked to cardiovascular diseases and can wreak havoc on the body´s arteries. This cholesterol transformation joins the other negative effects from the inhalation of vehicular exhaust, including early cell and tissue damage, inflation and hardening of the arteries. Researchers from the University of California Los Angeles (UCLA) helped conduct this study, including researchers from other institutions, and their results are now available in the online edition of the journal Arteriosclerosis, Thrombosis and Vascular Biology.

Urban areas are particularly subjected to emission particles, or pollutants from vehicle exhaust. According to the researchers, these particles are covered in chemicals that have been found to cause oxidation. Though this process has been discovered, it is not well understood. To find their results, the academic researchers subjected lab mice to these emission particles for two weeks. In this short amount of time, the mice showed signs of oxidation in their blood and liver. This damage was not reversed after being surrounded with filtered air the following week. Dr. Jesus Araujo, an associate professor of medicine and director of environmental cardiology at the David Geffen School of Medicine at UCLA, blames a transformation in HDL cholesterol for this oxidation in mice.

"This is the first study showing that air pollutants promote the development of dysfunctional, pro-oxidative HDL cholesterol and the activation of an internal oxidation pathway, which may be one of the mechanisms in how air pollution can exacerbate clogged arteries that lead to heart disease and stroke," said Dr. Araujo, the senior author of the study.

The researchers also exposed a different group of mice to emissions particles without following up with filtered air and another group of mice to only air for two weeks. This part of the study was led by Michael E. Rosenfeld, professor of environmental and occupational health sciences at the University of Washington.

"The biggest surprise was finding that after two weeks of exposure to vehicle emissions, one week of breathing clean filtered air was not enough to reverse the damage," said Rosenfeld.

Each group of mice was subjected to about the same amount of emission particles that mine workers are often exposed to.

Following the tests, Dr. Araujo, Professor Rosenfeld and the rest of the team analyzed blood and tissue samples from the mice to see if the protective properties of HDL cholesterol were intact. Both groups of mice that were exposed to two weeks of the emissions particles had their HDL “markedly altered” after the study. For example, their HDL was less able to protect the mice from oxidation and inflammation, two effects brought on by LDL, or “bad” cholesterol. Mice who had only been subjected to filtered air did not have the same results. The emissions groups of mice also saw a two-to-threefold increase in oxidation products in their blood and even the activation of the oxidation process in their liver. These results have led the researchers to urge those living in urban areas to limit their expose to outside pollutants, as this damage may not be reversed once it has occurred.