This observation is the result of chance. Bioinformatics scientist Mark Parisian and colleagues at McGill University were trying to better understand the mechanisms involved in the onset of pain when they made a discovery that seemed to change the traditional concept of acute pain treatment.
The Montreal team followed 98 people who attended a pain management clinic for acute back pain. Blood samples were taken from these patients during their first appointments and then three months later, with the aim of comparing their genetic information. The researchers’ goal was to compare the data of those whose lower back pain was resolved with data of patients whose suffering became chronic.
” It’s a bit like taking an inventory of what was going on in their blood over time. What would be different between people who heal quickly and those who stretch? »
What the researcher and his collaborators found was a surprise.
All analyzes led us to neutrophils, notes Mr. Parisien. Neutrophils are white blood cells that are involved in the body’s defense against bacterial infections, but are also present in the early stages of acute inflammation.
” Changes in gene expression were observed in subjects whose pain disappeared between the two appointments, indicating that neutrophils also play a major role in resolving pain. »
Rapid regulation of inflammatory responses by neutrophils appears to protect against the development of chronic painResearcher continues.
Main Medicines Non-steroidal anti-inflammatory drugs:
- acetylsalicylic acid (aspirin)
- celecoxib (Celebrex)
- diclofenac (Voltaren)
- ibuprofen (Advil, Motrin)
- indomethacin (Indoside)
- Meloxicam (Mobic and Viflodex)
- naproxen (Aleve)
Experiments on mice
This discovery led the team to adjust neutrophil levels in groups of rodents who underwent the same surgery to test the effect of these cells on pain control.
These experiments showed that blocking neutrophils in time prolongs up to ten times the pain experienced by mice.
One group of mice received early treatment with nonsteroidal anti-inflammatory drugs (NSAIDs) for pain relief.
The sedative effects of anti-inflammatories have been observed on acute postoperative pain. So these drugs protect against pain, but the suffering continued over timeMark Parisien notes.
This result has not been observed with other pain relievers such as acetaminophen (Tylenol) or opioids (codeine, morphine, oxycodone).
” You still have to be careful, because while mice have an immune system similar to humans, it is not identical. And humans have much more neutrophils in their blood than mice. »
back to humans
Armed with these results obtained in rodents, McGill’s team returned to verify their findings in more humans. She conducted an analysis of the records of 500,000 people participating in the UK Biobank, a medical and genetic database built over 20 years in the UK.
This analysis shows that participants who took NSAIDs for pain were more likely to develop chronic pain two to ten years later.
Again, this effect has not been seen in people taking acetaminophen or other pain relievers.
For Dr. Anne-Marie Benard, chronic pain anesthesiologist and professor at Université Laval, all these findings are very interesting, even if they remain in the field of primary research for the time being.
” The idea that blocking inflammation can interfere with pain healing isn’t entirely new, but how it was brought up with such stark evidence is intriguing. »
Dr. Benard thinks this is necessary
justice These results.
What the study with the patient bank shows is an association. We did not refer in a clear, distinct, and precise way to a cause-and-effect relationship.
Mark Parisien and his colleagues understand the limits of their work.
” Our testimony remains circumstantial. Ideally, this should be validated in other cohorts, for example using the CARTaGENE Quebec database and randomized, double-blind clinical trials. »
The authors thus realize that further work must be done to confirm their findings, which, in part, call into question conventional pain relief therapies.
The trade-off between treatment of acute pain versus treatment of chronic pain must be evaluatedExplains Mr. Parisien who adds that
Sometimes a short-term fix can cause long-term problems.
The publication of this work caused quite a stir in the world of pain therapy.
This study is very interesting because it opens the way for reflection, especially for health professionals.says Bree Benard.
” We often think that absolutely nothing should hurt in life. I’m not saying you have to put up with extreme pain, but sharp pain is a useful signal from the body to take a break, not to step on your foot or dance when your back hurts. […] The body does things right and when you allow it to, it creates an inflammatory response to heal. »
Now, should we throw anti-inflammatories in the trash? no. However, it shows us that inflammation is essential to the healing process.she adds.
- Data collected by Statistics Canada shows that nearly 8 million Canadians suffer from chronic pain.
- Acute low back pain is defined as pain that lasts six weeks or less.
- Chronic low back pain is described as deep, throbbing, dull, or burning pain that is localized in the lower back or travels down the leg and persists for more than three months.
Create new medicines
Mr. Parisien invokes the idea of a rescue to improve or develop new drugs to counteract the harmful effects of NSAIDsStream.
” The acute pain-reducing effect of anti-inflammatories can be maintained by masking the prolonging effect of a protein complex. »
To this end, the study also demonstrated that injection of a complex of proteins (S100A8/A9) normally released by neutrophils prevents the development of long-term pain caused by an anti-inflammatory drug.
Details of this work are published in the journal Translational Medicine Sciences (A new window) (in English).
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