The Journal of Neuroscience, July 15, 2002, 22(14):5900-5909
Inflammation-Dependent Cerebral Deposition of Serum Amyloid A
Protein in a Mouse Model of Amyloidosis
Jun-tao
Guo1,
Jin
Yu1,
David
Grass5,
Frederick C.
de
Beer2, and
Mark S.
Kindy1, 3, 4
Departments of 1 Biochemistry and
2 Internal Medicine, and 3 Stroke Program of
the Sanders-Brown Center on Aging, University of Kentucky, Lexington,
Kentucky 40536, 4 Veterans Affairs Medical Center,
Lexington, Kentucky 40506, and 5 Xenogen Corporation,
Princeton, New Jersey 08540
The major pathological hallmark of amyloid diseases is the presence
of extracellular amyloid deposits. Serum amyloid A (SAA) is an
apolipoprotein primarily produced in the liver. Serum protein levels
can increase one thousandfold after inflammation. SAA is the precursor
to the amyloid A protein found in deposits of systemic amyloid A
amyloid (AA or reactive amyloid) in both mouse and human. To study the
factors necessary for cerebral amyloid formation, we have created a
transgenic mouse that expresses the amyloidogenic mouse Saa1 protein in
the brain. Using the synapsin promoter to drive expression of the
Saa1 gene, the brains of transgenic mice expressed both
RNA and protein. Under noninflammatory conditions, transgenic mice do
not develop AA amyloid deposits in the brain; however, induction of a
systemic acute-phase response in transgenic mice enhanced amyloid
deposition. This deposition was preceded by an increase in cytokine
levels in the brain, suggesting that systemic inflammation may be a
contributing factor to the development of cerebral amyloid. The
nonsteroidal anti-inflammatory agent indomethacin reduced inflammation
and protected against the deposition of AA amyloid in the brain. These
studies indicate that inflammation plays an important role in the
process of amyloid deposition, and inhibition of inflammatory cascades
may attenuate amyloidogenic processes, such as Alzheimer's disease.
Key words:
Alzheimer's disease; transgenic; inflammation; serum
amyloid A; indomethacin; cytokines; microglia
Copyright © 2002 Society for Neuroscience 0270-6474/02/22145900-10$05.00/0