What’s your poison? Researchers engineer toxin to target pain


Tiffany Lee, July 1, 2016 | View original publication

What’s your poison? Researchers engineer toxin to target pain

A team of UNL researchers has cherry-picked its poison – one that may help ease the chronic pain suffered by millions of people each year.

By reprogramming the guidance system of the world’s most potent toxin, the researchers have engineered a bacterial protein that could potentially deliver therapeutic drugs directly to the sensory nerve cells responsible for a multitude of chronic pain issues.

The feat came courtesy of Clostridium botulinum, a class of bacteria that produces the toxin perhaps best known for reducing wrinkles in the form of Botox. Though the botulinum toxin occasionally kills by infecting wounds or poisoning food, it has also been used to treat muscle disorders, migraines and other maladies.

“The reason we’re doing this is because these bacterial toxins, which are proteins, are really good delivery devices,” said doctoral student Ben Pavlik, lead author of a recent study detailing the team’s work. “They have evolved over millions of years to be really good at putting a payload, or some kind of a detrimental molecule, inside a cell.

“That mechanism is really interesting. We wanted to investigate it and see if we could manipulate that in order to do some new, interesting things with it.”

Pavlik and his colleagues began with the so-called C2 version of the C. botulinum protein, which features independent sections dedicated to carrying its toxic payload and determining which cells it will attack. But C2 is far from picky, Pavlik said, binding to many different types of cells in the human body.

To help the protein focus on the peripheral neuron cells that relay pain signals to the central nervous system, the team swapped out C2’s guidance system and borrowed that of its more selective cousin, C1.

After also replacing the C2’s toxic payload with easily traceable fluorescent molecules, the team found that its engineered protein successfully targeted in vitro cells featuring the same receptors that coat peripheral neurons in the body.

“There are over 100 peripheral nerve disorders that are the result of diseases, viruses or people’s genetics,” Pavlik said. “A delivery system just to treat these (specific cells) would be great, because a lot of conventional therapeutics … are toxic or have bad side effects or cannot access the inside of cells, where they need to do their therapeutic work.

“This sort of delivery system allows you to use low doses that are targeted to a particular cell type and will carry a therapeutic that is customized for that particular disease.”

Pavlik said the team’s technique could also allow researchers to home in on other strategic cell targets and more easily study the inner workings of the cells themselves.

“People have been using toxins to investigate neuron physiology for a long time,” he said. “But … you couldn’t tailor them to do whatever you want them to do or carry whatever molecule you want them to carry. This (discovery) could expand the research toolkit for neurophysiologists.”

Pavlik and Paul Blum, a Charles Bessey Professor of biological sciences, have collaborated with NUtech Ventures to patent their technique and are currently in talks to license it. The duo also recently formed a company, Neurocarrus LLC, aimed at further developing biomedical therapies to combat pain that stems from tissue injury, inflammation and nerve damage.

The team published its recent findings in the journal Scientific Reports. Pavlik and Blum authored the study with Kevin Van Cott, associate professor of chemical and biomolecular engineering, and Elizabeth Hruska, a senior in pre-health. The researchers received support from the Defense Threat Reduction Agency and the UNL Cell Development Facility.

Biology Engineering Health