What Causes Rosacea?
Research May Offer New Clues
What really causes rosacea? The answer
is that no one knows. But researchers working at labs in San Diego
and New York City may have found some important clues that could
help solve this mystery.
The first key finding came when a team of researchers led by a
dermatologist from San Diego discovered that cathelicidin, a protein
that naturally occurs in the body, could cause the redness of
rosacea. Cathelicidin normally protects the skin from infection.
The next step was to learn why cathelicidin causes redness in people
with rosacea. To find out, the researchers took skin samples from 11
people with rosacea and 10 people who did not have rosacea. In the
skin of every person with rosacea, they found an excessive amount of
cathelicidin. They also found an abundance of the molecule that
converts cathelicidin from inactive to active. None of the people
without rosacea had these excessive amounts.
To find out if these high levels could induce rosacea, the team
produced these excessively high levels in mice. In each case, the
mice that had the high levels showed signs of rosacea on their skin
— redness, visible blood vessels, bumps, and pimple-like lesions.
These findings led the researchers to conclude that the way the body
processes cathelicidin determines whether it defends the skin
against infection or causes inflammation.
A separate team of researchers has been working on the role that
another chemical may play in rosacea. This team, lead by a
dermatologist from New York City, discovered that adenosine
triphosphate (ATP) may play a role in rosacea. ATP is released by
the nervous system. It appears that stress, a common rosacea
trigger, may activate the nervous system to release ATP. The
researchers found that when the nerves of people with rosacea
release ATP into the skin, a series of unique chemical events
occurs. These events eventually lead to the bumps and pus-filled
lesions of rosacea.
What this Research Means to People Living with Rosacea
While the cause remains a mystery, this research suggests that
patients who have bumps, pus-filled lesions, and redness may not
need long-term treatment with an antibiotic to control their
rosacea. If inflammation causes these signs of rosacea, then
treatment that effectively controls inflammation should be
The data collected during the clinical trials that looked at the
effectiveness and safety of non-antibiotic dosage doxycycline
further supports this finding. During these clinical trials, the
non-antibiotic dosage of doxycycline (also known as the
anti-inflammatory dosage) effectively reduced the bumps and
pus-filled lesions of rosacea.
Not having to take an antibiotic for the long term represents a
major advancement in the treatment of the bumps, pus-filled pimples,
and redness of rosacea. Long-term use of an antibiotic can cause
undesirable side effects such as extreme sun sensitivity, yeast
infections in women, and antibiotic resistance. The latter occurs
when an antibiotic becomes ineffective because a person takes the
antibiotic too often or for too long.
These research findings also provide more evidence that rosacea is a
medical condition. It is clear that chemical processes in the body
have gone awry, so rosacea is clearly not just a cosmetic concern.
More Research Needed
Before these findings can be used to develop treatment for rosacea,
more questions must be answered. The researchers need to know why
people with rosacea have these high levels of cathelicidin. They
must explain why these high levels lead to inflammation. They also
need to find out if other agents produced by the nerves can cause
the effects similar to ATP.
The researchers have already begun the studies needed to answer
these questions. What they discover next could change the face of
rosacea treatment. It also could show, as have past studies, that
there is an association but nothing more.
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content solely developed by the American Academy of Dermatology