Tarantula venom could hold key to IBS pain relief

Researchers from The University of Queensland’s Institute for Molecular Bioscience (IMB) have discovered that molecules from the venom of one of the world’s largest spiders could be used to develop pain blockers for people with irritable bowel syndrome (IBS).

Of 28 spiders screened by the research team, the venom of the Venezuelan Pinkfoot Goliath tarantula — which has a leg span of up to 30 cm — showed the most promise. The findings are published in the journal Pain.

Led by IMB’s Professor Richard Lewis — in collaboration with Flinders University’s Professor Stuart Brierley and the South Australian Health and Medical Research Institute — the team hopes to find effective pain relief for chronic intestinal pain.

“All pains are complex but gut pain is particularly challenging to treat, and affects around 20% of the world’s population,” Professor Lewis said.

“Current drugs are failing to produce effective pain relief in many patients before side effects limit the dose that can be administered.”

Professor Brierley said IBS and other gastrointestinal and bladder disorders cause chronic visceral pain, which affects the internal organs.

“Internal organs have a complex network of sensory nerves that have a wide array of voltage-gated ion channels and receptors to detect stimuli,” he said.

“The hypersensitivity of these nerves in disease often contributes to the development of pain.”

Voltage-gated ion channels open and close in response to changes across the cell membrane, with their dysfunction identified as a cause of chronic visceral pain.

Professor Lewis said spider venoms contain hundreds of mini proteins known as peptides that can inhibit voltage-gated ion channels from opening.

“Unfortunately these peptides aren’t completely selective for pain targets,” he said.

“Our goal was to find more specialised pain blockers that are potent and target pain sodium channels for chronic visceral pain, but not those that are active in the heart and other channels.”

The team found two peptides isolated from the tarantula venom inhibited the most important ion channels underlying pain, with one particularly potent at reducing the sensory nerves of the bladder and colon and nearly stopping chronic visceral pain in a model of IBS.

“We now have a really strong understanding of the structure and function of these spider venom peptides,” Professor Lewis said.

“The highly selective ones have potential as treatments for pain, while others are useful as new research tools to allow us to understand the underlying drivers of pain in different diseases.”

The research, funded by the National Health and Medical Research Council, evolved from 15 years of studying the potential of medicines developed from venoms.

Image caption: Two pain-blocking peptides were found in the spider venom. Image credit: Institute for Molecular Bioscience, The University of Queensland.