Nav: Home

Opioids produce analgesia via immune cells

January 17, 2017

Opioids are the most powerful painkillers. Researchers at the Charité - Universitätsmedizin Berlin have now found that the analgesic effects of opioids are not exclusively mediated by opioid receptors in the brain, but can also be mediated via the activation of receptors in immune cells. These findings represent a novel concept in our understanding of the mechanisms of opioid analgesia. Results from this research, published in the journal Brain, Behavior, and Immunity*, show that pain reduction in mice was mediated by the activation of opioid receptors in immune cells.

Opioids such as morphine are the gold standard for the treatment of severe pain. Until now, opioids were considered to reduce pain by inhibiting the activity of sensory neurons in the brain. However, most pain conditions are associated with damage to peripheral tissue (skin, joints, viscera), which is infiltrated by immune cells. "This prompted us to ask whether opioids could also inhibit pain by acting on immune cells," explains Prof. Dr. Halina Machelska, a researcher at the Department of Anesthesiology and Critical Care Medicine at the Charité - Campus Benjamin Franklin. "We hypothesized that opioids act at opioid receptors on immune cells and release endogenous opioid peptides such as endorphins, enkepahlins and dynorphins. The secreted opioid peptides would then activate neuronal opioid receptors and reduce pain."

Using an animal model of neuropathic pain and three different exogenous opioids (opioid receptor agonists), the researchers led by Prof. Machelska demonstrated that all three agonists alleviated pain. However, animals with reduced numbers of immune cells experienced much weaker analgesia. Interestingly, this analgesia was fully restored when the numbers of immune cells were again increased. This effect was only mediated by immune cells containing opioid receptors. "We were able to show that opioid agonists activate opioid receptors on immune cells, which triggered the release of endogenous painkillers (opioid peptides) and produced analgesia in a mouse model of neuropathic pain," explains Prof. Machelska. She adds, "This led us to conclude that opioids can exert enhanced analgesia when they act directly in painful tissue - providing that this tissue is inflamed and contain immune cells." These findings are relevant for many pain conditions, including arthritis, nerve damage, post-surgical and cancer pain, since all of them are associated with an immune response. Furthermore, opioids acting directly within peripheral inflamed tissue, outside of the brain, will not produce undesirable effects such as nausea, breathing difficulties, and addiction. These findings provide incentives for the development of new opioids exerting analgesia selectively in peripheral damaged tissue infiltrated by immune cells expressing opioid receptors.
-end-
* Melih Ö. Celik, Dominika Labuz, Karen Henning, Melanie Busch-Dienstfertig, Claire Gaveriaux-Ruff, Brigitte L. Kieffer, Andreas Zimmer, Halina Machelska. Leukocyte opioid receptors mediate analgesia via Ca2+-regulated release of opioid peptides. Brain Behav Immun. 2016 Oct. doi: 10.1016/j.bbi.2016.04.018. Epub 2016 Apr 30. http://dx.doi.org/10.1016/j.bbi.2016.04.018

Contact:
Prof. Dr. Halina Machelska
Department of Anesthesiology and Critical Care Medicine
Charité-Universitätsmedizin Berlin
Campus Benjamin Franklin
Tel: +49 30 8445 3851
Email: halina.machelska@charite.de

Links: Department of Anesthesiology and Critical Care Medicine

Charité - Universitätsmedizin Berlin

Related Immune Cells Articles:

Identification of new populations of immune cells in the lungs
In an article published in Nature Communications, the Immunophysiology Laboratory of the GIGA Institute, headed by Prof.
A genomic barcode tracker for immune cells
A new research method to pinpoint the immune cells that recognise cancer could significantly change how we treat the disease.
Scientists reminded immune cells on what side they should be
International group of scientists in the joint study of the laboratory of the Wistar Institute, University of Pittsburgh and I.M.
Dead cells disrupt how immune cells respond to wounds and patrol for infection
Immune cells prioritise the clearance of dead cells overriding their normal migration to sites of injury.
Study gives new perspective on production of blood cells and immune cells
A new study provides a thorough accounting of blood cell production from hematopoietic stem cells.
More Immune Cells News and Immune Cells Current Events

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Erasing The Stigma
Many of us either cope with mental illness or know someone who does. But we still have a hard time talking about it. This hour, TED speakers explore ways to push past — and even erase — the stigma. Guests include musician and comedian Jordan Raskopoulos, neuroscientist and psychiatrist Thomas Insel, psychiatrist Dixon Chibanda, anxiety and depression researcher Olivia Remes, and entrepreneur Sangu Delle.
Now Playing: Science for the People

#537 Science Journalism, Hold the Hype
Everyone's seen a piece of science getting over-exaggerated in the media. Most people would be quick to blame journalists and big media for getting in wrong. In many cases, you'd be right. But there's other sources of hype in science journalism. and one of them can be found in the humble, and little-known press release. We're talking with Chris Chambers about doing science about science journalism, and where the hype creeps in. Related links: The association between exaggeration in health related science news and academic press releases: retrospective observational study Claims of causality in health news: a randomised trial This...