Absence of C1q leads to less neuropathology in transgenic mouse models of Alzheimer's disease.
C1q, the recognition component of the classical complement activation pathway, is a multifunctional protein known to be expressed in brain of Alzheimer's disease (AD) patients. To experimentally address the role of C1q in AD, a mouse model lacking C1q (APPQ-/-) was generated by crossing Tg2576 animals (APP) with C1q-deficient mice. The pathology of APPQ-/- was compared with that of APP mice and B6SJL controls at 3-16 months of age by immunohistochemistry and Western blot analysis. At younger ages (3-6 months), when no plaque pathology was present, no significant differences were seen in any of the neuronal or glial markers tested. At older ages (9-16 months), the APP and APPQ-/- mice developed comparable total amyloid and fibrillar beta-amyloid in frontal cortex and hippocampus; however, the level of activated glia surrounding the plaques was significantly lower in the APPQ-/- mice at 12 and 16 months. In addition, although Tg2576 mice showed a progressive decrease in synaptophysin and MAP2 in the CA3 area of hippocampus compared with control B6SJL at 9, 12, and 16 months, the APPQ-/- mice had significantly less of a decrease in these markers at 12 and 16 months. In a second murine model for AD containing transgenes for both APP and mutant presenilin 1 (APP/PS1), a similar reduction of pathology was seen in the APPPS1Q-/- mice. These data suggest that at ages when the fibrillar plaque pathology is present, C1q exerts a detrimental effect on neuronal integrity, most likely through the activation of the classical complement cascade and the enhancement of inflammation.
Department of Molecular Biology and Biochemistry, University of California, Irvine, California 92697, USA.
Maria Isabel
MI
Fonseca
Jun
J
Zhou
Marina
M
Botto
Andrea J
AJ
Tenner
D000367:Age Factors; D000544:Alzheimer Disease / Q000276:immunology* / Q000378:metabolism / Q000473:pathology*; D016229:Amyloid beta-Peptides / Q000032:analysis; D000818:Animals; D015153:Blotting, Western; D015922:Complement C1q / Q000032:analysis / Q000235:genetics / Q000502:physiology*; D004195:Disease Models, Animal; D007150:Immunohistochemistry; D051379:Mice; D018345:Mice, Knockout; D008822:Mice, Transgenic; D009457:Neuroglia / Q000378:metabolism; D058225:Plaque, Amyloid / Q000473:pathology*
D016229:Amyloid beta-Peptides; D015922:Complement C1q