MAR 18, 2020 5:45 AM PDT

Immune cells can ease chronic pain

WRITTEN BY: Tara Fernandez

 

In the words of C.S. Lewis, “Pain insists upon being attended to.” This is especially true for patients suffering from chronic pain, lasting over 12 weeks. In developed countries, pain is the most common medical reason that drives people to visit their doctor’s office. The biology of pain is incredibly complex and despite intense research into pharmaceutical interventions to alleviate it, much has yet to be learned about how different tissue systems influence the distressing sensation.

In the context of chronic pain, the brain continues to receive pain signals, long after an injury or trauma to the body has healed. Inflammation of peripheral nerves have been linked to the onset of chronic pain, a process that involves the effects of multiple inflammatory cells and the protein signals they secrete, known as cytokines. 

Researchers have recently identified that one particular cytokine, called interleukin-4 (IL-4), recruits immune cells to the site of inflammation, triggering the release of endogenous pain-relieving opioids that results in long term pain relief.

The research team from the Charité-Universitätsmedizin Berlin studied the relationship between IL-4 and pain relief using an animal model of sciatica. Injections of IL-4 into tissue surrounding an inflamed nerve was found to have a temporary analgesic effect, lasting for a few minutes. Recurrent daily IL-4 injections, on the other hand, induced the recruitment of M2 macrophages, large white blood cells that “eat” pathogens and dead cells at the site of inflammation. The scientists, led by Halina Machelska from Charité's Department of Experimental Anesthesiology, also discovered a lesser-known role that macrophages play — relieving pain. In their experiments, macrophages had a surprising effect of providing longer term pain relief, lasting up to eight days, even after the injections were stopped.

Upon deeper analysis, macrophages isolated from the site of IL-4 injections were observed to secrete various opioids including endorphins, enkephalin and dynorphin. These chemicals interact with opioid receptors, acting similarly to drugs such as morphine and codeine. 

The researchers believe that these findings have implications in a wide variety of conditions, including cancer, arthritis and neurodegenerative diseases. According to Machelska, "As these analgesic effects occur at the peripheral nerves, outside the brain, it is possible to prevent undesirable side effects such as sedation, nausea and addiction. These findings may offer new perspectives in our endeavors to develop alternative pain management options for patients."



Sources: EurekAlert, JCI.

About the Author
  • Tara Fernandez has a PhD in Cell Biology and has spent over a decade uncovering the molecular basis of diseases ranging from skin cancer to obesity and diabetes. She currently works on developing and marketing disruptive new technologies in the biotechnology industry. Her areas of interest include innovation in molecular diagnostics, cell therapies, and immunology. She actively participates in various science communication and public engagement initiatives to promote STEM in the community.
You May Also Like
APR 11, 2021
Genetics & Genomics
Trial Shows Personalized Cancer Vaccines are Safe
APR 11, 2021
Trial Shows Personalized Cancer Vaccines are Safe
Vaccines are mostly known as tools to prevent illness. But cancer vaccines are a bit different, and aim to treat existin ...
APR 28, 2021
Cell & Molecular Biology
Learning More About the Sugars That Mediate Immune Interactions
APR 28, 2021
Learning More About the Sugars That Mediate Immune Interactions
Sugar is something sweet to add to your food, but just like fat, different types of sugars play important roles in biolo ...
MAY 11, 2021
Immunology
Immune Cells Help Brain Tumors Spread, but We Can Stop Them
MAY 11, 2021
Immune Cells Help Brain Tumors Spread, but We Can Stop Them
Researchers have discovered how a glitch in the brain’s immune system can inadvertently cause an accelerated growt ...
JUN 10, 2021
Immunology
Decoding the Immune System's Language
JUN 10, 2021
Decoding the Immune System's Language
Scientists at UCLA have decoded the “vocabulary” of immune cells—six distinct signals used as flares t ...
JUN 28, 2021
Cell & Molecular Biology
Bringing Light to Extracellular Vesicles
JUN 28, 2021
Bringing Light to Extracellular Vesicles
Though originally thought of as strictly a waste disposal system, extracellular vesicles (EVs) have been shown to have m ...
JUL 01, 2021
Immunology
Simple Dietary Changes Could Help Ease Skin and Joint Inflammation
JUL 01, 2021
Simple Dietary Changes Could Help Ease Skin and Joint Inflammation
Eating too much sugar and fat can have a dramatic impact on the gut microflora, which in turn can flare up inflammatory ...
Loading Comments...