How chronic pain develops

EU project on chronic pain

12/01/2013

A new EU project should help to understand how chronic pain develops and what role RNA molecules play in it. The project is designed for four years.

20 percent of Europeans suffer from chronic pain
A new EU project under the direction of Innsbruck will help to find out what role RNA molecules play in the development of chronic pain. For many people, the expected outcomes could be significant, with 20 percent of Europeans suffering from chronic pain, according to the Europe-wide Pain Proposal Consensus Report. In addition to the immense personal consequences, such as the fear of social isolation or a job loss, would have huge economic consequences: at 1.5 to three percent of European economic output (GDP), the cost of chronic pain estimated.

Years can go by until diagnosis
What is particularly striking in the report is that a quarter of patients have to wait more than a year for a correct diagnosis. And one in ten does not even have one after five years. An accurate diagnosis would be the basis for effective treatment. But even just under 40 percent of chronic pain patients reported that they were not adequately treated.

Different types of pain
Basically, to distinguish between the types of pain. On the one hand, there is the nociceptive pain that arises when pain receptors are mechanically, chemically or thermally irritated. This is an important body early warning system. On the other hand, there is the neuropathic pain caused by damage to nerves. In addition, pain often accompanies other diseases. But almost all types of pain have in common that the nervous and immune systems work closely together.

Research is well advanced
Research is already well advanced in some areas. For example, it is known that the patterns (the relative abundances) of signal molecules are altered. In neuropathic pain, for example, there are more pro-inflammatory cytokines and less anti-inflammatory. „If you block a cytokine with drugs, then this has an effect, but the other cytokines are not affected“, explains Michaela Kress, professor at the Med-University Innsbruck. From this knowledge, the question arose as to what would be if one could influence the common cause of the altered cytokine levels?

Discovery a few years ago
Advances in genetic research have further fueled this idea: microRNA (miRNA) plays an important role in the regulation of many processes in the body. These small molecules, made up of around 20 bases, are single-stranded unlike the more familiar DNA, and come from a very early stage of evolution. In the common opinion there were no proteins at that time. Only a few years ago, it was discovered that miRNA is crucial for the regulation of gene expression, ie, the transcription of genes (DNA) into the messenger RNA (mRNA) and the subsequent assembly of proteins according to this blueprint.

Researchers from seven countries
For some diseases, such as cancer or cardiovascular disease, the influence of miRNA is well known, according to Kress. Since this is not yet the case with pain, the EU project ncRNAPAIN will be kicked off next weekend with a kick-off meeting to advance in this area. Researchers from seven countries cooperate under the direction of Kress in the four-year project. The budget is just under six million euros. „We want to understand the mechanisms of how chronic pain develops and what role miRNA plays“, so Kress.

Investigations based on two types of pain
This is to be investigated on the basis of two types of pain: on the one hand polyneuropathy, in which 40 percent of all diabetics suffer ten years after onset of the disease, and on Sudeck's disease (CRPS), a chronic pain that sometimes results from injuries. Among other things, the project will use methods of bioinformatics to predict which miRNAs will affect which genes. „For some we know a connection, in many we suspect one“, explained Kress.

Fast effective pain therapy for patients as a target
In the clinic, this basic knowledge will then be used to identify miRNA patterns that could then serve as biomarkers, ie to predict the individual's risk of suffering from chronic pain, for example after a bone fracture or the onset of diabetes. In addition, the biomarkers could show which drugs the patients respond to. „Our long-term goal is to provide the optimal effective pain therapy for each patient as soon as possible“, said Kress. However, it remains unclear whether the research results could justify new therapeutic approaches for neuropathic pain. (Ad)

Picture: Sigrid Rossmann