Researchers Niels Eijkelkamp and Michiel van der Vlist from UMC Utrecht have received a so-called 'ENW-M-2 grant' of over € 700,000 from the Netherlands Organization for Scientific Research (NWO). They will use this grant to study how the body eliminates inflammatory pain. In this way they hope to understand what goes wrong in people with chronic pain that does not disappear. With the ultimate long-term goal: new treatments for chronic pain.

Pain after inflammation or tissue damage usually disappears over time. But in a fairly large proportion of patients with inflammatory diseases, it does not. They continue to suffer from pain even after the inflammation has disappeared. In total, no less than one in five people suffer from chronic pain. A large proportion of them have been diagnosed with an inflammatory disease, such as rheumatoid arthritis, osteoarthritis or inflammatory bowel disease (such as Crohn's disease). In order to develop new treatments for this type of persistent pain, experts must first have a good understanding of how inflammatory pain normally develops. And more importantly, how this type of pain disappears again.

Releasing energy factories

The research group of Dr. Niels Eijkelkamp at the Center for Translational Immunology (CTI) at UMC Utrecht has been trying to understand for some time now the characteristics of (chronic) pain. At the end of last year, his group, together with Prof. Linde Meyaard's group, published a scientific paper on the role that macrophages play in pain.

Macrophages are immune cells that attack and eat pathogens. "For some time now we have known that these cells have many more tasks," Eijkelkamp explains. "They also play a role in the elimination of pain." The researchers discovered that macrophages can deliver mitochondria (the cell's "energy factories") to nerve cells. These nerve cells transmit pain signals from the inflamed tissue, which is why someone feels pain. "We found that releasing mitochondria helps to stop the pain," Eijkelkamp said.

Answering questions

How this works? That, unfortunately, is not yet clear. Eijkelkamp: "As you often see in scientific research, our study also raised questions." With the money that NWO is now making available, the pain expert can take the next step. He will do lab research with immunologist Dr. Michiel van der Vlist.

The two experts hope to better understand how the nervous system and the immune system ‘talk’ to each other. They will achieve this by answering a number of questions. Questions such as: how do nerve cells attract macrophages that can expel pain? What causes macrophages to turn off pain? And what exactly changes in nerve cells when they receive mitochondria (the "energy factories") from macrophages?

By answering these questions, the researchers hope to eventually better understand how pain dissipates after inflammation. "We can use that knowledge to develop new treatments for chronic pain," says van der Vlist. "How nice would it be if one day we could help 1.5 billion people get rid of their chronic pain?"