Time-dependent reduction in Abeta levels after intracranial LPS administration in APP transgenic mice.
Inflammation has been argued to play a primary role in the pathogenesis of Alzheimer's disease (AD). Lipopolysaccharide (LPS) activates the innate immune system, triggering gliosis and inflammation when injected in the central nervous system. In studies described here, APP transgenic mice were injected intrahippocampally with 4 or 10 microg of LPS and evaluated 1, 3, 7, 14, or 28 days later. Abeta load was significantly reduced at 3, 7, and 14 days but surprisingly returned near baseline 28 days after the injection. No effects of LPS on congophilic amyloid deposits could be detected. LPS also activated both microglia and astrocytes in a time-dependent manner. The GFAP astrocyte reaction and the Fcgamma receptor microglial reaction peaked at 7 days after LPS injection, returning to baseline by 2 weeks postinjection. When stained for CD45, microglial activation was detected at all time points, although the morphology of these cells transitioned from an ameboid to a ramified and bushy appearance between 7 and 14 days postinjection. These results indicate that activation of brain glia can rapidly and transiently clear diffuse Abeta deposits but has no effect on compacted fibrillar amyloid.
Alzheimer Research Laboratory, Department of Pharmacology and Therapeutics, University of South Florida, Tampa, FL 33612-4799, USA.
Donna L
DL
Herber
Lisa M
LM
Roth
David
D
Wilson
Nedda
N
Wilson
Jerimiah E
JE
Mason
Dave
D
Morgan
Marcia N
MN
Gordon
D000544:Alzheimer Disease / Q000188:drug therapy* / Q000473:pathology / Q000503:physiopathology*; D016229:Amyloid beta-Peptides / Q000378:metabolism*; D016564:Amyloid beta-Protein Precursor / Q000235:genetics*; D000818:Animals; D001253:Astrocytes / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D004333:Drug Administration Routes; D006624:Hippocampus / Q000187:drug effects / Q000473:pathology; D007267:Injections; D008070:Lipopolysaccharides / Q000008:administration & dosage*; D051379:Mice; D008822:Mice, Transgenic; D017628:Microglia / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D013997:Time Factors
D016229:Amyloid beta-Peptides; D016564:Amyloid beta-Protein Precursor; D008070:Lipopolysaccharides