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lectrostimulation of the vagus nerve
may be key to reducing the symptoms of rheumatoid arthritis, according to
findings that scientists presented at the Annual European Congress of
Rheumatology in Madrid, Spain.
Electrostimulation of the vagus nerve may help reduce the symptoms of rheumatoid arthritis.
This
research gives hope that there may be a new way to help treat this autoimmune
condition.
The
vagus nerve, which is a very long nerve that runs between the brain and the
neck, chest, and abdomen, is a complex structure.
Previous
research has found an inflammatory reflex in the vagus nerve that reduces the
production of cytokines, including certain molecules that are a component of
autoimmune conditions. These molecules are called tumornecrosis factor
(TNF).
The
immune systems of healthy people block TNF, but in those with certain autoimmune conditions, excess
TNF makes its way into the bloodstream and causes inflammation and a
higher rate of symptoms associated with the conditions.
TNF
is a target in many rheumatoid arthritis (RA) drugs, such
as infliximab (Remicade)
or etanercept(Enbrel). Many
people call these drugs TNF-blockers.
The researchers thought that if they could boost this
naturally occurring reflex in the vagus nerve, it might have a similar result —
or one that was even better, as drugs that aim for TNF also suppress the immune
system and have other unwelcome side effects.
"This
is a really exciting development," says Prof. Thomas Dörner, Chairperson
of the Scientific Programme Committee at the Annual European Congress of
Rheumatology, which this year takes place in Madrid, Spain.
"For
many [people living with] RA, current treatments don't work, or aren't
tolerated. These results open the door to a novel approach to treating not only
RA but other chronic inflammatory diseases. This is certainly an area for
further study," adds Prof. Dörner.
Small neurostimulator led to big findings
The
researchers implanted a small neurostimulator, called a MicrioRegulator, into
14 people with RA. To qualify for the study, each person had tried at least two
medications that worked in different ways but that hadn't helped reduce their
symptoms.
The
scientists then divided the participants into three groups: a placebo group, a
group that had vagus stimulation once per day, and a group that had vagus
stimulation four times per day.
The
study, which took place over 12 weeks, revealed that those in the once-per-day
group had a much better result, symptom-wise, than those in the other two
groups — including those that had stimulation four times each day.
Both
stimulation groups also had a distinct reduction of more than 30% in their
cytokine levels during the course of the study.
How RA affects people
Unlike
osteoarthritis, which occurs when cartilage in the joints breaks down over
time, RA can develop at any age. That said, it is more likely
to affect people ages 30–60.
In
the United States, there are around 1.5 million people with the condition, and
it tends to affect around three times as many women than men.
In
those with RA, the body's immune system is overactive and attacks healthy
tissue in the body — in this case, the lining of the joints.
Over
time, this inflammation can damage cartilage and the bones themselves, with
joint spacing becoming more narrow. This results in a loss of mobility and
flexibility. Once the damage has set in, it is irreversible; so, the goal is to
identify the condition early and treat it aggressively.
Symptoms
can vary from person to person, but early symptoms tend to include joint pain
or swelling that lasts for 6 weeks or longer, stiffness in the morning that
lasts for at least 30 minutes, or both.
RA
tends to affect more than one joint, and it also affects smaller joints in the
hands, feet, and wrists more often than it does larger joints. Also, RA is
often symmetrical and affects joints on both sides of the body.
What does the future hold?
Although
surgically implanting small neurostimulators into every person with RA is
probably not feasible, reasonable, or required, this study does shine a light
on potential therapy that can help those who do not respond well to traditional
medications for the condition.
The
findings of this research will also pave the way for future studies.
"Our pilot study suggests this novel
MicroRegulator device is well tolerated and reduces signs and symptoms of
[RA]," says Dr. Mark Genovese, the James W. Raitt Endowed Professor of
Medicine at Stanford University in California.
"These data support the study
of this device in a larger placebo-controlled study as a novel treatment
approach for [RA] and possibly other chronic inflammatory diseases."
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