Cigarette smoke has long overshadowed nicotine as the main culprit for heart disease, but a new study suggests that nicotine itself may stimulate the disease process by altering cell structures and promoting fatty plaque deposits, the hallmark of cardiovascular disease, to accumulate in vessels.
Brown University researchers, scheduled to present their results at the 56th Annual Meeting of the Biophysical Society, found that nicotine exposure changes cell structure in a way that further induces migration and invasion of the smooth muscle cells lining of blood vessels.
Researchers said that the invading cells produced by nicotine exposure is especially good at remodeling structures called podosomes, which are actin-rich, adhesive structures located on the ventral surface of monocytic myeloid lineage cells, stimulated endothelial cells and cultured Src-transformed cancer cells.
The study discovered that the nicotine-podosome link leads further degradation of blood vessels by forming vessel-clogging fatty deposits known as plaque which can accumulate and lead to atherosclerosis, restricting blood flow throughout the body.
Investigators said their findings question the actual health benefits of nicotine products like gum, patches or electronic cigarettes people use to help quit their smoking habit.
"The finding that nicotine is as effective as cigarette smoke in enhancing cellular structural changes, and breakdown of scaffold proteins by vascular smooth muscle cells, suggests that replacing cigarette smoking by nicotine treatment may have limited beneficial effects on atherosclerosis," said lead researcher Chi-Ming Hai, professor of medical science at Brown University in a statement released on Thursday.
The new findings highlight the multistep process of plaque formation which appeared to be largely influenced by nicotine.
Researchers said that plaque formation starts as a reaction to cellular injury, and develops into harmful and chronic inflammation of the vessel walls, which attract white blood cells, that further inflame the vessels
Damaging inflammation of the blood vessels can also be triggered by the body’s chemical reaction to high blood sugar, modified low-density lipoproteins or harmful cholesterol, physical stress from high blood pressure, or chemical insult from tobacco smoke.
“Now nicotine itself appears to remodel key structures in a way that primes and enhances the invasion of smooth muscle lining the vessel wall,” researchers wrote in a statement.
“Identifying a possible nicotine-posodome link in the invasion step of plaque formation process suggests a new means of intervening in the process: targeting the cell structures that are changed by nicotine and that promote invasion of the smooth muscle lining the vessel wall. If a therapy could prevent, slow, or reverse that step, it would likely interrupt the plaque-production cycle,” they concluded.
The results of the latest study underlines the arguments voiced by many health advocates who have pushed the U.S. Food and Drug Administration to rigorously evaluate modified-risk tobacco products, which are becoming increasingly popular, with only objective scientific results before allowing those products to be marketed as low-risk.
In December the Institute of Medicine reported that only about 6 percent of smokers are able to successfully quit tobacco use, and because quitting is so difficult, many smokers will probably want products that allow them to continue smoking with less health risks.
However IOM said that there were still no research that proves that modified-risks tobacco products to be safer than traditional cigarettes, these new products can ultimately be just as risky as regular cigarettes, and urged the federal health agency to have “trusted third parties oversee the conduct of research” to determine the health effects of modified-risk tobacco products.
The American Lund Association had also released a statement in December praising the IOM recommendations.
“The American Lung Association commends the IOM for its recognition that if a tobacco product is allowed to be marketed as ‘safer’ that the product must actually be safer,” said Charles Connor, President and CEO of the American Lung Association in the statement.
“Decades ago the tobacco industry developed light and low tobacco products that were no less harmful than those already on the market. Millions of Americans, who switched to those so-called ‘light’ and ‘low-tar’ products instead of quitting, died as a result of these claims,” Connor said.