Protein can lead to drug treatments for chronic pain

Scientists have created a new bio-therapeutic molecule that could be used to treat neurological disorders such as chronic pain and epilepsy.
Scientists from 11 research institutes, including Dr Enrico Ferrari from the University of Lincoln, UK, created and characterised a new molecule that was able to alleviate hypersensitivity to inflammatory pain.
By separating elements of clostridium botulinum and clostridium tetani neurotoxins, commonly known as Botox and tetanus toxin respectively, the scientists were able to develop a model to re-join the molecule proteins yielding new biomedical properties, without unwanted toxic effects.
While the Botox element is able to block neuronal communication - and therefore pain signals - for months, the tetanus component targets the engineered toxin to the central nervous system, rather than stopping at exterior neurons that are the normal target of Botox.

The combination of the two effects is of great interest for neuroscience and can be applied to the treatment of several neurological disorders, particularly chronic pain conditions.
Botox and tetanus neurotoxins hold great promise for clinical applications, but since they are the most lethal proteins known to man, their paralytic activity was a stumbling block until now, researchers said.

"The toxins were split into parts so they were unable to function. Then later they were reassembled using a 'zipping' system so they can operate in a safe way," said Ferrari, one of the lead authors of the study.
"The re-engineered chimera toxin has very similar characteristics to Botox and is still able to block neurotransmission release, but the paralytic effect is a lot less. We then added a tetanus molecule which targets the chimera to where the pain signals travel towards the central nervous system," he said.

Preliminary data on animal models has now been collated at University College London and future clinical trials are expected to fully characterise the new bio-therapeutic.
"Many painkillers relieve the pain temporarily and have various side effects. The selling point of this molecule is that the pain relief could last up to seven months, in a similar way that Botox injections for removing wrinkles last for several months," Ferrari said.
The study was published in the scientific journal Bioconjugate Chemistry.