Amyloid-beta immunization effectively reduces amyloid deposition in FcRgamma-/- knock-out mice - PubMed (original) (raw)

Amyloid-beta immunization effectively reduces amyloid deposition in FcRgamma-/- knock-out mice

Pritam Das et al. J Neurosci. 2003.

Abstract

Direct immunization with amyloid beta protein (Abeta) and passive transfer of anti-Abeta antibodies reduce Abeta accumulation and attenuate cognitive deficits in transgenic models of Alzheimer's disease (AD). The reduction in Abeta deposition has been proposed to involve microglial phagocytosis of Abeta immune complexes via Fc receptors (FcRs). We have examined the efficacy of Abeta immunization in amyloid precursor protein (APP) transgenic mice crossed into FcR-gamma chain knock-out mice (FcRgamma-/-). As might be expected from previous studies on macrophages, phagocytosis of Abeta immune complexes via FcR was completely impaired in microglia cells isolated from FcRgamma-/- mice. Thus, we immunized APP Tg2576 transgenic mice that were crossed in the FcRgamma-/- background with Abeta1-42 and then analyzed the effect on Abeta accumulation. In APP Tg2576 transgenic mice crossed to FcRgamma-/-, Abeta1-42 immunization significantly attenuated Abeta deposition, as assessed by both biochemical and immunohistological methods. The reduction in Abeta accumulation was equivalent to the reduction in deposition seen in Abeta1-42 immunized, age-matched, FcR-sufficient Tg2576 mice. We conclude that after Abeta immunization, the effects of anti-Abeta antibodies on Abeta deposition in APP Tg2576 transgenic mice are not dependent on FcR-mediated phagocytic events.

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Figures

Figure 1.

Figure 1.

Microglia from FcRγ-/- mice exhibit defective uptake of anti-Aβ immune complexes. A, Microglia isolated from wild-type (Wt, top panels) mice and FcRγ-/- mice (bottom panels) were incubated with Cy3–Aβ in the presence of increasing concentrations of Ab9 antibody for 10 min without fucoidan (-Fu) or in the presence of 500μg/ml fucoidan (+Fu). Magnification, 40×. Data represented are from one of three independent experiments. B, Quantitation of Cy3–Aβ internalization in the presence of increasing concentrations of Ab9 and fucoidan. *p < 0.01; **p < 0.01. C, Quantitation of Cy3–Aβ internalization in the presence of increasing concentrations of Ab42–5. *p < 0.01. D, Quantitation of Cy3–Aβ internalization by wt microglia in the presence of competing IgG. Microglia were incubated with Cy3–Aβ complexed with 20 μg/ml of Ab9 antibody (Aβ + Ab9), in the presence of 100 μg of purified mouse IgG (Aβ + Ab9 + IgG), and in the presence of 500 μg/ml of fucoidan (Aβ + Ab9 + IgG) + Fu. *p < 0.01. Data represented are from one of two independent experiments.

Figure 2.

Figure 2.

Aβ levels were significantly reduced in the Aβ1–42-immunized 11- to 12-month-old Tg2576 × FcRγ-/- mice. Mice were killed after immunization with Aβ1–42 for 3 months, and both SDS-soluble (SDS) and SDS-insoluble formic acid extractable (FA) fractions were analyzed by capture ELISA. A, Tg2576 × FcRγ-/- mice, 11–12 month old (n = 5 per group); B, wt Tg2576 mice, 11–12 month old (n = 6 per group). Statistical analyses are provided in Results.

Figure 3.

Figure 3.

Quantitative image analysis of amyloid plaque burden in the 11- to 12-month-old Tg2576 × FcRγ-/- mice. A, Immunostained amyloid plaque burden is reduced in the 11- to 12-month-old Tg2576 × FcRγ-/- mice immunized with Aβ1–42 (*p < 0.004) and in the 11- to 12-month-old Tg2576 mice (**p < 0.005). B, Congo red-stained plaque burden is significantly reduced in the 11- to 12-month-old Tg2576 × FcRγ-/- mice immunized with Aβ1–42 (*p < 0.005) and in the 11- to 12-month-old Tg2576 mice (**p < 0.05). C, Quantitation of CD45-stained activated microglia revealed no statistically significant differences between immunized and control groups of the 11- to 12-month-old Tg2576 × FcRγ-/- and the 11- to 12-month-old Tg2576 mice.

Figure 4.

Figure 4.

Representative pictures of immunostained Aβ plaques (stained with Ab9 antibody) in the neo cortex of 11- to 12-month-old Tg2576 × FcRγ-/- mice (A) and control group (B) immunized with Aβ1–42 (A, B, magnification 40×). Representative pictures of Congo red-stained plaques (red) decorated with microglia immunostained with anti-mouse CD45 (black) in the neo cortex of 11- to 12-month-old Tg2576 × FcRγ-/- mice (C) and control group (D) immunized with Aβ1–42 (C, D, magnification 100×).

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References

    1. Bacskai BJ, Kajdasz ST, Christie RH, Carter C, Games D, Seubert P, Schenk D, Hyman BT ( 2001) Imaging of amyloid-beta deposits in brains of living mice permits direct observation of clearance of plaques with immunotherapy. Nat Med 7: 369-372. - PubMed
    1. Bacskai BJ, Kajdasz ST, McLellan ME, Games D, Seubert P, Schenk D, Hyman BT ( 2002) Non-Fc-mediated mechanisms are involved in clearance of amyloid-β in vivo by immunotherapy. J Neurosci 22: 7873-7878. - PMC - PubMed
    1. Bamberger ME, Harris ME, McDonald DR, Husemann J, Landreth GE ( 2003) A cell surface receptor complex for fibrillar β-amyloid mediates microglial activation. J Neurosci 23: 2665-2674. - PMC - PubMed
    1. Bard F, Cannon C, Barbour R, Burke RL, Games D, Grajeda H, Guido T, Hu K, Huang J, Johnson-Wood K, Khan K, Kholodenko D, Lee M, Lieberburg I, Motter R, Nguyen M, Soriano F, Vasquez N, Weiss K, Welch B, Seubert P, Schenk D, Yednock T ( 2000) Peripherally administered antibodies against amyloid beta-peptide enter the central nervous system and reduce pathology in a mouse model of Alzheimer disease. Nat Med 6: 916-919. - PubMed
    1. Bard F, Barbour R, Cannon C, Carretto R, Fox M, Games D, Guido T, Hoenow K, Hu K, Johnson-Wood K, Khan K, Kholodenko D, Lee C, Lee M, Motter R, Nguyen M, Reed A, Schenk D, Tang P, Vasquez N, Seubert P, Yednock T ( 2003) Epitope and isotype specificities of antibodies to beta-amyloid peptide for protection against Alzheimer's disease-like neuropathology. Proc Natl Acad Sci USA 100: 2023-2028. - PMC - PubMed

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