Nearly one in five people suffers from the insidious and often devastating problem of chronic pain. That the problem persists, and is growing, is striking given the many breakthroughs in understanding the basic biology of pain over the past two decades. Research published online in Nature Medicine points to potential solutions.
Gene that encodes crucial pain receptor may be key to
individualizing therapy for major health problem
Nearly one in five people suffers from the insidious and often
devastating problem of chronic pain.
That the problem persists, and is growing, is striking given the
many breakthroughs in understanding the basic biology of pain over
the past two decades. A major challenge for treating chronic
pain is to understand why certain people develop pain while others,
with apparently similar disorders or injuries, do not. An equally
important challenge is to develop individualized therapies that
will be effective in specific patient populations.
Research published online in Nature Medicine points to
solutions to both challenges. A research team led by Prof. Jeffrey
Mogil of McGill University in Montreal and Prof. Michael Salter of
The Hospital for Sick Children (SickKids), affiliated with the
University of Toronto, has identified a major gene affecting
chronic pain sensitivity. The findings also suggest a new approach
to individualizing treatment of chronic pain.
The gene that the researchers identified encodes the pain
receptor known as P2X7. Specifically, the scientists discovered
that a single amino-acid change in P2X7 controls sensitivity to the
two main causes of chronic pain: inflammation and nerve damage.
The amino-acid change is known to affect only one function of
P2X7 receptors - the forming of pores that permit large molecules
to pass through - while leaving intact the other function, of
allowing much tinier ions to flow through. Using a peptide that
targets pore formation only, the researchers found that pain
behaviours were dramatically reduced.
The scientists then examined genetic differences among human
patients suffering from two distinct types of persistent pain:
chronic post-mastectomy pain and osteoarthritis. In both
cases, they found that individuals with genetically inherited low
pore formation in P2X7 receptors experienced lower pain levels.
"Our findings indicate that it may be possible to develop drugs
that block pores in this crucial receptor, while leaving its other
function intact - thereby killing pain while minimizing side
effects," said Prof. Mogil, E.P. Taylor Professor of Pain Research
in McGill's Department of Psychology.
Prof. Salter, Anne and Max Tanenbaum Chair in Molecular Medicine
at SickKids, said these discoveries "point toward a new strategy
for individualizing the treatment of chronic pain." Scientists from
the U.S. and Israel also contributed to the study.
The study was supported by the Krembil Foundation, the Louise
and Alan Edwards Foundation, the US National Institutes of Health
(NIH), the Canadian Institutes of Health Research (CIHR) and
SickKids Foundation.