Vaccines have been a standard in the medical battle against deadly disease for more than half a century, and have helped bring many of the major childhood killers like smallpox and whooping cough under control. While vaccines have traditionally been used to battle infections from viruses and bacteria, scientists are starting to use them to fight other invaders. In the case of smoking, they’ve set their sights on nicotine.
As the key ingredient in tobacco, nicotine acts on the brain to produce many of the pleasurable effects of smoking and that leads to addiction. That addiction keeps smoking pleasurable even when smokers know it causes a variety of health problems including cancers, decreased bone density, increased risk for heart disease and stroke and fetal damage in pregnant women.
Researchers wondered if there was a way to make smoking less pleasurable, and they realized that vaccines could be the key. If a vaccine against nicotine could be developed, the body would neutralize it before it made it to the brain. This would mean that smoking wouldn’t lead to the pleasurable and addictive feelings normally associated with smoking because the nicotine would never even make it to the brain. Uncoupling pleasure from smoking would make it easier to quit for good because smoking a cigarette wouldn’t lead to good feelings in those with the vaccine.
But even though nicotine is a foreign chemical, it doesn’t act in a way that makes the immune system pay attention to it. Researchers first had to figure out how to make the body recognize nicotine as foreign and respond to it with an attack. They did this using a mix of chemicals called adjuvants. These chemicals are harmless to health, but push the body to recognize a foreign invader and attack it.
This had been done in the past, but even with an adjuvant, only about 30% of test subjects responded to nicotine after the vaccine. A new study has figured out why. Many chemicals come in a left- and right-handed version. These versions can have radically different functions in the body. The most notable example was thalidomide, a morning sickness drug developed in the 1970s. One version of the drug decreased nausea, but the other led to birth defects.
In this case, the researchers realized that previous vaccines hadn’t paid attention to the different versions of nicotine. They had made vaccines that included both kinds without looking to see what the normal mix was in the smoke that enters a smoker’s lungs. They had assumed the immune system wouldn’t know the difference and would attack both versions. To test if this was the case, this team made two vaccines: one with only left-handed nicotine and another with only right-handed nicotine. They injected these into two separate groups of mice to see if their immune systems could make antibodies targeted at specific forms of nicotine.
They found that the mice made antibodies specific to the form of nicotine they were exposed to and that those antibodies weren’t very good at inactivating nicotine of the other kind. That means if the mix of nicotine in a vaccine is wrong, it could cause the body to make ineffective antibodies against a form of nicotine that isn’t present in high amounts in cigarette smoke. Paying attention to these different versions could lead to the development of an effective vaccine against nicotine that could help smokers kick the habit for good.