Multiple Chemical Sensitivity Archives

What causes allergies? or Multiple Chemical Sensitivity

May 20, 2000
RESEARCHERS PRESENT NEW THEORY FOR ALLERGIC DISEASES

Johns Hopkins researchers have discovered, to their
surprise, that a nervous system protein may have a
significant role in asthma, hay fever and other allergies.
According to the new research reported in the May issue of
the American Journal of Respiratory and Critical Care
Medicine, the protein, nerve growth factor (NGF), may be
responsible for making allergy sufferers more sensitive to
irritants such as tobacco smoke.

"Hay fever and asthma now seem to derive from events not
only in the respiratory system, but also from a nervous
system that is overreacting to stimuli," says Vassilis
Koliatsos, M.D., an associate professor of pathology,
neurology and neuroscience at the Johns Hopkins School of
Medicine.

In the United States, hay fever, medically known as
allergic rhinitis, affects up to 36 million people and
asthma affects about 14 million, at a cost of several
billions of dollars per year. For decades, scientists have
known that individuals who have allergies and asthma are
more reactive to irritants such as cold, dry air and
tobacco smoke, but until now, they haven't known why.

Hopkins allergy researchers took to the trail of NGF for
several reasons. First, Koliatsos, who is an expert on the
use of NGF in experiments to treat nerve and brain
disorders, informed the allergy researchers that using NGF
to treat Alzheimer's caused patients excessive pain. NGF,
found naturally in the body, is a small, potent molecule
that helps maintain certain nerve cells and prods other
nerve cells to grow and communicate with others. "It looked
like the pain syndromes we saw in these patients shared
many of the same mechanisms with respiratory allergy," says
Koliatsos.

Specifically, both involved an inflammatory response by
cells in lung or nerves. Secondly, Hopkins allergy
researchers had found that individuals who were hyper-
responsive to irritants had nerves in their airways that
were abnormally reactive. And thirdly, researchers at
Hopkins and other institutions had shown that, in animal
studies, NGF could cause significant changes in nerve
fibers.

For example, mice that were genetically engineered to
produce excessive amounts of NGF in their lungs developed
increased density of nerves in the airways as well as
increased responsiveness to irritants.

To test whether an allergic reaction in humans would
increase NGF, Alvin Sanico, M.D., an assistant professor of
medicine at Hopkins, and his colleagues enlisted 20
volunteers who had hay fever and 10 who were healthy. As
part of the study, the scientists collected nasal washings
before and after administering ragweed or grass pollen
extracts by nasal spray. They found that baseline levels of
NGF in the nasal washings of the allergic group were
significantly higher compared to the healthy group. In
addition, they discovered that exposure to the allergen
caused a significant increase in NGF levels in the allergic
group but had no effect on the healthy individuals.

"This finding provides further understanding of a very
common disease and hopefully may open new possibilities for
novel forms of treatment in the future," says Sanico, lead
author of the study. For example, researchers in the future
may identify a drug that could block the effects of these
molecules and decrease hyper-responsiveness.

"Our frustrations with the side effects of NGF in clinical
trials for Alzheimer's disease and nerve disorders helped
lead to this study," says Koliatsos. "It is very rewarding
to see another clinical opportunity for this very
interesting molecule."

Sanico says the new discovery can bridge the two major
features of allergic airway disease: inflammation (which
causes typical allergy symptoms such as congestion) and
hyper-responsiveness to irritants. During inflammation,
cells that participate in an allergic reaction, such as
mast cells and eosinophils, are stimulated, and these cells
have now been shown to be capable of producing NGF.

Sanico says more studies that are needed to further
understand this new facet of allergic airway disease in
humans are currently under way.

The study was funded by grants from the National Institutes
of Health and Johns Hopkins. The authors of the study are
Alvin Sanico, Todd Gleeson, Susan Bora, David Proud,
Vassilis Koliatsos and Alkis Togias from Johns Hopkins in
Baltimore, Maryland, as well as John Bienenstock and
Andrzej Stanisz from McMaster University in Ontario,
Canada.

--JHMI--

Media Contact: Kate O'Rourke (410)955-8665
korourke@jhmi.edu

Follow Ups:

• Re: What causes allergies? or Multiple Chemical Sensitivity (Archive in LGS.) Walt Stoll 09:26:47 6/27/00 (0)

In Reply to: What causes allergies? or Multiple Chemical Sensitivity posted by Arsen Lupin on June 24, 2000 at 07:26:18:

Hi, Arsen.

Thanks for the information. There is no doubt that these findings are true (but only a VERY small part of the entire picture).

What they will eventually have to learn is that more than 95% of hypersensitivities (allergies are a small part of this condition) are caused by LGS and the simultaneous leakyness of the blood-brain barrier that naturally occurs when LGS is present (because of the tightly linked embryological relationiship between the barrier at the gut lining and the barrier at the blood-brain lining). Watch for the "discovery" even though this has been known for years already.

Namaste`

Walt