German Center for
Neurodegenerative Diseases (DZNE)
Holbeinstraße 13-15
53175 Bonn
Germany
Press Embargo: 27.08.2015, 3 PM CEST
Dr Marcus Neitzert
Science Editor
Phone:+49 228/43302 271
marcus.neitzert@dzne.de
www.dzne.de
Press Release
Mystery of polar bear Knut’s disease finally solved
The animal suffered from an autoimmune disease previously known only
in humans.
Leibniz Institute for Zoo and Wildlife
Research (IZW)
Alfred-Kowalke-Str. 17
10315 Berlin
Germany
Steven Seet
Head of Unit Press &
Communications
Phone: +49 30/5168 125
Mobile:+49 177 857 26 73
seet@izw-berlin.de
www.leibniz-izw.de
Berlin, 27th August 2015
Knut, the famous polar bear of the Berlin Zoological Garden (Germany)
died of encephalitis, as diagnosed soon after his death. However, the
cause of his disease has remained elusive until now. A team of scientists
from the German Center for Neurodegenerative Diseases (DZNE), the
Leibniz Institute for Zoo and Wildlife Research (IZW) and the Charité Universitätsmedizin Berlin has now solved the case: The polar bear
suffered from an autoimmune disease of the brain. This non-infectious
illness is called “anti-NMDA receptor encephalitis”, with symptoms in
human patients similar to those displayed by Knut. Knut is the first wild or
domestic animal in which this form of encephalitis has been
demonstrated. The results were reported in the scientific journal
“Scientific Reports”. The authors propose that errant immune responses
may be associated with brain diseases more commonly than previously
assumed.
Knut was a favourite with the public across the world and became well
known far beyond the borders of Berlin. The polar bear drowned on 19th
March 2011 after suffering epileptic seizures and falling into the enclosure
pool. Scientists under the leadership of the IZW intensively investigated the
potential causes of Knut’s death and revealed that the seizures were caused
by encephalitis, suspecting an infection by an unknown pathogen. The exact
cause of the disease remained a mystery.
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Charité – Universitätsmedizin Berlin
Charitéplatz 1
10117 Berlin
Germany
Manuela Zingl
Deputy Press Spokesperson
Phone: +49 30/450 570 400
manuela.zingl@charite.de
www.charite.de
Zoologischer Garten Berlin AG
Hardenbergplatz 8
10787 Berlin
Germany
Christiane Reiss
Phone:+49 30/25401 221
presse@zoo-berlin.de
www.zoo-berlin.de
Cooperation of neuroscientists and wildlife researchers
Dr Harald Prüß, who is a researcher at the Berlin site of the DZNE and a
specialist in neurology at the Charité, read the autopsy report and
discovered parallels to his own studies on human brain diseases. The
neuroscientist contacted Prof Alex Greenwood, leader of the Department of
Wildlife Diseases at the IZW. Could it be possible that Knut might have
suffered from an autoimmune disease of the brain? The two scientists
quickly agreed to follow up this line of research together. Greenwood, head
of the primary study on Knut, had considered that there might be noninfectious cause of disease, but until the collaboration with Prüß there was
no real possibility to test for this class of diseases in wild animals. The IZW
had stored samples of the polar bear’s brain which were now used for
analysis.
"This study provided us with the possibility to extend and refine our test
methods", says Prüß. The analysis revealed that the polar bear had
developed "anti-NMDA receptor encephalitis". In the tissue samples of the
animal, the scientists demonstrated the presence of NMDA-receptor
antibodies, the characteristic proteins for this encephalitis.
"Until now, this autoimmune disease has only been known in humans. In
this illness, the body’s immune system overreacts and produces antibodies
which damage nerve cells instead of fighting against pathogens", Prüß
explains. "Epileptic seizures, hallucinations and dementia are among the
possible symptoms."
Until recently unknown
These diseases were discovered only a few years ago. According to Prüß,
until recently, patients with encephalitis for which viruses or bacteria were
not identified as causative agent remained undiagnosed, and their origin a
mystery. “In the past few years, the number of unsolved cases has
decreased considerably. Since 2010, we have known that the majority of
patients with encephalitis of unknown etiology are suffering from antiNMDA receptor encephalitis, once infectious causes were ruled out. There
are now standard tests to diagnose the disease”, says the neuroscientist.
“In humans this disease is relatively responsive to medical treatment.”
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“We were quite intrigued by this result”, comments IZW scientist
Greenwood on this discovery. “The anti-NMDA receptor encephalitis has
been described only very recently in humans. Clearly it is also of importance
for other mammals. We are relieved to have finally solved the mystery of
Knut’s disease, especially as these insights could have practical applications.
If the current therapy for human patients is also suitable for wild animals,
many cases of fatal encephalitis in zoos may be prevented in future.”
Antibody tests in dementia patients
“Knut’s disease has further implications. It is possible that autoimmune
diseases of the nervous system might be far more common in humans and
other mammals than previously assumed”, says Greenwood.
“We might underdiagnose autoimmune inflammations in human patients
suffering psychoses or memory disturbances, because these patients are
not routinely screened for associated antibodies. As a result they may not
receive the optimal treatment. Therefore, I believe it is reasonable to
examine patients for associated antibodies, especially if the cause of a
dementia is unknown. These antibodies can be held in check by
pharmaceutical means. There are also other forms of encephalitis, where
errant antibodies against other receptor molecules are important in disease
development”, comments DZNE researcher Prüß.
„The research results are an important contribution to understanding
autoimmune diseases of the nervous systems in animals. One can only
congratulate the scientists of the German Center for Neurodegenerative
Diseases, the German Leibniz Institute for Zoo and Wildlife Research and
the Charité - Universitätsmedizin Berlin. They have made it possible that in
the future, diseases in animals similar to Knut’s could be diagnosed earlier
and treated”, says Dr Andreas Knierim, Director of the Berlin Zoological
Garden.
Original publication
Prüss H, Leubner J, Wenke NK, Czirják GÁ, Szentiks CA, Greenwood AD (2015): Anti-NMDA
Receptor Encephalitis in the Polar Bear (Ursus maritimus) Knut. SCIENTIFIC REPORTS, doi:
10.1038/srep12805.
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Photos (caption)
01-03: Knut 2007, author: Zoo Berlin/04: Knut 2008, author: Zoo Berlin/05: Knut with
encephalitis, authors: DZNE, IZW & Zoo Berlin. Download link (20 MB):
http://www.zoovet-conference.org/knut/knut.zip
Press Conference
Meet the experts on 27th of August 2015, 11.00 am – 13.00 pm CEST at Schloss
Friedrichsfeld in the “Tierpark Berlin”, Am Tierpark 125, 10319 Berlin, Germany. All
information at the press conference will be under embargo till 3.00 pm CEST. Contact:
Steven Seet; +49 177 857 26 73; seet@izw-berlin.de.
The German Center for Neurodegenerative Diseases (DZNE) investigates the causes of
diseases of the nervous system and develops strategies for prevention, treatment and care. It
is a cross-institutional network under the leadership of the Helmholtz Association of German
Research Centres with sites in Berlin, Bonn, Dresden, Göttingen, Magdeburg, Munich,
Rostock/Greifswald, Tübingen and Witten. The DZNE cooperates closely with universities,
their clinics and other research facilities.
www.dzne.de
www.twitter.com/dzne_en
www.dzne.de/facebook
The Leibniz Institute for Zoo and Wildlife Research (IZW) investigates the vitality and
adaptability of wildlife populations in mammalian and avian species of outstanding
ecological interest that face anthropogenic challenges. It studies the adaptive value of traits
in the life cycle of wildlife, wildlife diseases and clarifies the biological basis and development
of methods for the protection of threatened species. Such knowledge is a precondition for a
scientifically based approach to conservation and for the development of concepts for the
ecologically sustainable use of natural resources. The IZW belongs to the Forschungsverbund
Berlin e.V. (www.fv-berlin.de) and the Leibniz Association (www.leibniz-gemeinschaft.de).
www.izw-berlin.de
The Charité is one of the largest university hospitals in Europe. Here, 3700 doctors and
scientists heal, do research and teach at the top international level. More than half of the
German Nobel Prize winners in medicine and physiology come from the Charité, among them
Emil von Behring, Robert Koch and Paul Ehrlich. The Charité also has an international
reputation for excellence in training. It extends over four campuses with almost 100 clinics
and institutes bundled under 17 CharitéCenters. With 13,100 employees, the Charité
generates about 1.5 billion euros in sales per year and is one of the largest employers in
Berlin. In 2010, the Charité could look back and joyously celebrated its 300-year anniversary.
Encephalitis and Paraneoplasia Consultation Hours at the Department of Neurology with
Experimental Neurology of the Charité:
http://neurologie.charite.de/patienten/hochschulambulanzen/enzephalitis_und_paraneopla
sien/
www.charite.de
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Since it opened in 1844, the Zoo Berlin is considered to be Germany’s number one zoological
garden and currently represents more species than any other zoo in the world. Over 17,000
animals from close to 1,500 species live right in the heart of Berlin, in its zoo and aquarium.
Besides unusual and exotic animals, such as kiwis and axolotl, the Zoo Berlin is home to many
endangered species as well as rare domestic breeds. The Tierpark Berlin, in the eastern part
of the city, also belongs to the Zoologischer Garten Berlin AG. Over 7,000 exotic animals from
815 species are at home here in Europe’s largest wildlife park, where they live in spacious
and diversified parkland. The number of visitors is also unique in Europe: more than 4.4
million guests visit the Zoo Berlin AG every year.
www.zoo-berlin.de, www.tierpark-berlin.de
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