Researchers are making breakthroughs on a decades-old quest to use our own bodies to defend against addiction — by priming our bodies to stop the small molecules that cause an addictive high before they reach the brain.Drugs like nicotine (which are in cancer-causing tobacco products like cigarettes) and cocaine not only cause expensive health problems and death, but also are a huge drain on society. Addicts often can’t work or build up large amounts of debt paying for their habit.
“There’s no question that drug addiction is a major problem with society, with everything from nicotine addiction and cigarette smoking, which is widespread with millions of people involved,” study researcher Dr. Ronald Crystal of Weil Cornell Medical centre told us. Nicotine addiction is “associated with significant development of disease, and then there’s addictions like cocaine, heroin, methamphetamines and so on that change social behaviour.”
Specifically, Crystal’s group is working to halt addiction to cocaine and nicotine using specially created vaccines. Vaccines could be given to addicts in recovery to stop their high if they relapse. [Read about the potential impacts of drug vaccines from Dr. Ronald Crystal.]
Priming the body
Photo: Graham Colm
The two vaccines use a special viral vector to introduce a gene into our liver cells. The virus isn’t known to cause disease and was especially created as a gene therapy vector. It has been used in other gene therapy trials and has been proven effective and safe for those uses. Based on how it performed in those uses, the vaccine should provide immunity against nicotine or cocaine with only one dose.It creates immunity by planting a gene into the body’s liver cells. The gene contains instructions for how the cell can make an antibody, the proteins made by the immune system that serve as a flag marking foreign objects in the body. In this case, the vaccine introduces a gene containing the antibody against either cocaine or nicotine. In their animal trials, the researchers saw the virus successfully inject the gene into liver cells, and saw that the liver then was able to create the antibody.
This antibody is being constantly created by the liver cells and pumped out into the body, so it’s always there at a moment’s notice to stop the drug in its tracks. When a person takes a drug the antibody binds to it, basically putting a bull’s-eye on the molecule, targeting it for destruction by the immune system. Cells called macrophages pick up the cocaine-antibody combination and shuttle it out of the body.
Stopping the drug
Photo: Valerie Everett / flickr
The antibodies work so fast that they can stop the drug from getting into the brain. After getting the vaccine, mice given cocaine don’t show the typical hyperactive effects of the high. In a separate study of monkeys, the brains of vaccinated monkeys don’t show cocaine interacting with the brain tissues.Similar effects were seen in nicotine-vaccinated mice. The effects last months, and probably years, Crystal said.
This type of vaccine could be created for any drug that acts by a small molecule getting into the brain including not only nicotine and cocaine, but also methamphetamine, and heroin. The downside: A new vaccine would have to be created and tested for every new drug that comes to the market, for example designer drugs like bath salts.
The latest on the nicotine gene therapy vaccine was published on June 27 in the journal Science Translational Medicine. And a recent study of the cocaine gene therapy vaccine was published on June 18 in the journal Human Gene Therapy.
The vaccines have been tested in animals, but more research needs to be done. Dr. Crystal suggests that the nicotine vaccine could be in clinical human trials in a couple of years, and the cocaine vaccine could be tested in humans within the next 12 months.
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