Chronic Inflammatory Pain Trigger Molecule Uncovered

Researchers have discovered that the genes involved in chronic pain are regulated by molecules inside small RNAs. The discovery could lead to the development of a brand new class of drugs to treat chronic pain caused by inflammatory conditions.

The research team was funded by the Biotechnology and Biological Sciences Research Council and working at University College London.

“When a person experiences chronic pain as a result of some sort of inflammation as in arthritis their pain threshold goes down very dramatically,” said lead researcher Professor John Wood from UCL, in a press release. “What they can normally do without pain, such as walking or putting on clothes, becomes very painful.

"Chronic inflammatory pain can be treated with pain-killing drugs analgesics but these usually have an impact on the whole body and may also dull our experience of acute pain, which is actually very important as it protects us from injury. Just imagine if you didn't get a sharp pain when you accidentally touch the oven you wouldn't be compelled to take your hand away quickly and could end up with a serious burn.

"What we would really like to be able to do is return the pain thresholds to normal in a person who has chronic inflammatory pain, rather than just numbing the whole body. This would mean that they still get the protection of acute pain. Currently, aspirin-like drugs that can do this have a number of side effects but the present discovery might make it possible to invent a class of drugs that act in a completely novel way."

The team studied mice lacking the enzyme called Dicer in some of their nerve cells. The mice responded normally to acute pain, but did not seem to be bothered by what would usually cause chronic inflammatory pain. The researchers found that Dicer makes small RNAs, which are re required for regulation of genes involved in chronic inflammatory pain. Since the mice lacked Dicer, the small RNAs were not created and inflammatory genes were expressed at low levels.

“Knowing that small RNAs are so important in chronic inflammatory pain provides a new avenue for developing drugs for some of the most debilitating and life-long conditions out there” Wood said. “We have identified small RNAs, which are possible drug targets.”