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Impact of amyloid β aggregate maturation on antibody treatment in APP23 mice.

Balakrishnan K, Rijal Upadhaya A, Steinmetz J, Reichwald J, Abramowski D, Fändrich M, Kumar S, Yamaguchi H, Walter J, Staufenbiel M, Thal DR - Acta Neuropathol Commun (2015)

Bottom Line: Protective effects on commissural neurons with highly ramified dendritic trees were observed only in 3-month-old β1-treated animals sacrificed at 5 months.Aβ antibody treatment was capable of protecting neurons from dendritic degeneration as long as Aβ aggregation was absent or represented B-Aβ stage 1 but had no protective or curative effect in later stages with mature Aβ aggregates (B-Aβ stage 3).These data indicate that the maturation stage of Aβ aggregates has impact on potential treatment effects in APP23 mice.

View Article: PubMed Central - PubMed

Affiliation: Institute of Pathology - Laboratory of Neuropathology, Center of Biomedical Research, University of Ulm, Helmholtzstrasse 8/1, D-89081, Ulm, Germany.

ABSTRACT

Introduction: The deposition of the amyloid β protein (Aβ) in the brain is a hallmark of Alzheimer's disease (AD). Removal of Aβ by Aβ-antibody treatment has been developed as a potential treatment strategy against AD. First clinical trials showed neither a stop nor a reduction of disease progression. Recently, we have shown that the formation of soluble and insoluble Aβ aggregates in the human brain follows a hierarchical sequence of three biochemical maturation stages (B-Aβ stages). To test the impact of the B-Aβ stage on Aβ immunotherapy, we treated transgenic mice expressing human amyloid precursor protein (APP) carrying the Swedish mutation (KM670/671NL; APP23) with the Aβ-antibody β1 or phosphate-buffered saline (PBS) beginning 1) at 3 months, before the onset of dendrite degeneration and plaque deposition, and 2) at 7 months, after the start of Aβ plaque deposition and dendrite degeneration.

Results: At 5 months of age, first Aβ aggregates in APP23 brain consisted of non-modified Aβ (representing B-Aβ stage 1) whereas mature Aβ-aggregates containing N-terminal truncated, pyroglutamate-modified AβN3pE and phosphorylated Aβ (representing B-Aβ stage 3) were found at 11 months of age in both β1- and PBS-treated animals. Protective effects on commissural neurons with highly ramified dendritic trees were observed only in 3-month-old β1-treated animals sacrificed at 5 months. When treatment started at 7 months of age, no differences in the numbers of healthy commissural neurons were observed between β1- and PBS-treated APP23 mice sacrificed with 11 months.

Conclusions: Aβ antibody treatment was capable of protecting neurons from dendritic degeneration as long as Aβ aggregation was absent or represented B-Aβ stage 1 but had no protective or curative effect in later stages with mature Aβ aggregates (B-Aβ stage 3). These data indicate that the maturation stage of Aβ aggregates has impact on potential treatment effects in APP23 mice.

No MeSH data available.


Related in: MedlinePlus

Immunoglobulin-bound Aβ detected in oligomers, protofibrils and fibrils in APP23 mice: Effects of β1 antibody treatment. Semiquantitative analysis of western blots after immunoprecipitation of immunoglobulin (antibody)-bound Aβ by precipitation of antibodies with protein G-coated magnetic beads. Subsequent western blot analysis with anti-Aβ1–17 revealed antibody-bound Aβ in the dispersible fraction of both β1- and PBS-treated mice at both ages. In 5-month-old β1-treated APP23 mice antibody-bound Aβ was found in the soluble fraction whereas no antibody-bound Aβ was precipitated in PBS-treated animals (* p < 0.05). At 11-months of age both, β1 and PBS-treated animals exhibited antibody bound soluble Aβ in similar amounts. Antibody-bound AβN3pE was not observed whereas 11-month-old (but not 5-month-old) APP23 mice showed similar amounts of dispersible antibody-bound pAβ. No soluble antibody-bound pAβ was seen. Graphs represent mean values (white symbols 5-month-old mice; black symbols 11-month-old mice) and standard errors (whiskers). (Full blots Additional file 10: Figure S7; Statistical analysis in Additional file 3: Table S3)
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Fig6: Immunoglobulin-bound Aβ detected in oligomers, protofibrils and fibrils in APP23 mice: Effects of β1 antibody treatment. Semiquantitative analysis of western blots after immunoprecipitation of immunoglobulin (antibody)-bound Aβ by precipitation of antibodies with protein G-coated magnetic beads. Subsequent western blot analysis with anti-Aβ1–17 revealed antibody-bound Aβ in the dispersible fraction of both β1- and PBS-treated mice at both ages. In 5-month-old β1-treated APP23 mice antibody-bound Aβ was found in the soluble fraction whereas no antibody-bound Aβ was precipitated in PBS-treated animals (* p < 0.05). At 11-months of age both, β1 and PBS-treated animals exhibited antibody bound soluble Aβ in similar amounts. Antibody-bound AβN3pE was not observed whereas 11-month-old (but not 5-month-old) APP23 mice showed similar amounts of dispersible antibody-bound pAβ. No soluble antibody-bound pAβ was seen. Graphs represent mean values (white symbols 5-month-old mice; black symbols 11-month-old mice) and standard errors (whiskers). (Full blots Additional file 10: Figure S7; Statistical analysis in Additional file 3: Table S3)

Mentions: Immunoprecipitation of antibody-bound Aβ by incubation of the brain samples with protein G magnetic beads without previous coupling to primary antibodies showed IgG-bound soluble Aβ in 5-month-old β1-treated mice detected with anti-Aβ1–17 antibodies, but not in PBS-treated animals (Fig. 6, Additional file 3: Table S3 and Additional file 10: Figure S7). Such a difference was not observed in 11-month-old mice. No soluble IgG-bound AβN3pE and pAβ was seen in 5- and 11-month-old APP23 mice (Fig. 6). In the dispersible fractions, immunoprecipitation with protein-G coated magnetic beads without primary antibody exposure and subsequent western blotting with anti-Aβ1–17 antibodies, showed detectable amounts of IgG-bound Aβ in both age and treatment groups, respectively, without significant differences among treatment (Fig. 6, Additional file 3: Table S3g and Additional file 10: Figure S7). AβN3pE was not seen in antibody-bound aggregates (Fig. 6, Additional file 3: Table S3g and Additional file 10: Figure S7). In 5-month-old APP23 mice no dispersible pAβ was observed in antibody-bound aggregates but 11-month-old animals exhibited dispersible pAβ in the precipitates without significant differences between the treatment groups (Fig. 6, Additional file 3: Table S3g and Additional file 10: Figure S7).Fig. 6


Impact of amyloid β aggregate maturation on antibody treatment in APP23 mice.

Balakrishnan K, Rijal Upadhaya A, Steinmetz J, Reichwald J, Abramowski D, Fändrich M, Kumar S, Yamaguchi H, Walter J, Staufenbiel M, Thal DR - Acta Neuropathol Commun (2015)

Immunoglobulin-bound Aβ detected in oligomers, protofibrils and fibrils in APP23 mice: Effects of β1 antibody treatment. Semiquantitative analysis of western blots after immunoprecipitation of immunoglobulin (antibody)-bound Aβ by precipitation of antibodies with protein G-coated magnetic beads. Subsequent western blot analysis with anti-Aβ1–17 revealed antibody-bound Aβ in the dispersible fraction of both β1- and PBS-treated mice at both ages. In 5-month-old β1-treated APP23 mice antibody-bound Aβ was found in the soluble fraction whereas no antibody-bound Aβ was precipitated in PBS-treated animals (* p < 0.05). At 11-months of age both, β1 and PBS-treated animals exhibited antibody bound soluble Aβ in similar amounts. Antibody-bound AβN3pE was not observed whereas 11-month-old (but not 5-month-old) APP23 mice showed similar amounts of dispersible antibody-bound pAβ. No soluble antibody-bound pAβ was seen. Graphs represent mean values (white symbols 5-month-old mice; black symbols 11-month-old mice) and standard errors (whiskers). (Full blots Additional file 10: Figure S7; Statistical analysis in Additional file 3: Table S3)
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Related In: Results  -  Collection

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Fig6: Immunoglobulin-bound Aβ detected in oligomers, protofibrils and fibrils in APP23 mice: Effects of β1 antibody treatment. Semiquantitative analysis of western blots after immunoprecipitation of immunoglobulin (antibody)-bound Aβ by precipitation of antibodies with protein G-coated magnetic beads. Subsequent western blot analysis with anti-Aβ1–17 revealed antibody-bound Aβ in the dispersible fraction of both β1- and PBS-treated mice at both ages. In 5-month-old β1-treated APP23 mice antibody-bound Aβ was found in the soluble fraction whereas no antibody-bound Aβ was precipitated in PBS-treated animals (* p < 0.05). At 11-months of age both, β1 and PBS-treated animals exhibited antibody bound soluble Aβ in similar amounts. Antibody-bound AβN3pE was not observed whereas 11-month-old (but not 5-month-old) APP23 mice showed similar amounts of dispersible antibody-bound pAβ. No soluble antibody-bound pAβ was seen. Graphs represent mean values (white symbols 5-month-old mice; black symbols 11-month-old mice) and standard errors (whiskers). (Full blots Additional file 10: Figure S7; Statistical analysis in Additional file 3: Table S3)
Mentions: Immunoprecipitation of antibody-bound Aβ by incubation of the brain samples with protein G magnetic beads without previous coupling to primary antibodies showed IgG-bound soluble Aβ in 5-month-old β1-treated mice detected with anti-Aβ1–17 antibodies, but not in PBS-treated animals (Fig. 6, Additional file 3: Table S3 and Additional file 10: Figure S7). Such a difference was not observed in 11-month-old mice. No soluble IgG-bound AβN3pE and pAβ was seen in 5- and 11-month-old APP23 mice (Fig. 6). In the dispersible fractions, immunoprecipitation with protein-G coated magnetic beads without primary antibody exposure and subsequent western blotting with anti-Aβ1–17 antibodies, showed detectable amounts of IgG-bound Aβ in both age and treatment groups, respectively, without significant differences among treatment (Fig. 6, Additional file 3: Table S3g and Additional file 10: Figure S7). AβN3pE was not seen in antibody-bound aggregates (Fig. 6, Additional file 3: Table S3g and Additional file 10: Figure S7). In 5-month-old APP23 mice no dispersible pAβ was observed in antibody-bound aggregates but 11-month-old animals exhibited dispersible pAβ in the precipitates without significant differences between the treatment groups (Fig. 6, Additional file 3: Table S3g and Additional file 10: Figure S7).Fig. 6

Bottom Line: Protective effects on commissural neurons with highly ramified dendritic trees were observed only in 3-month-old β1-treated animals sacrificed at 5 months.Aβ antibody treatment was capable of protecting neurons from dendritic degeneration as long as Aβ aggregation was absent or represented B-Aβ stage 1 but had no protective or curative effect in later stages with mature Aβ aggregates (B-Aβ stage 3).These data indicate that the maturation stage of Aβ aggregates has impact on potential treatment effects in APP23 mice.

View Article: PubMed Central - PubMed

Affiliation: Institute of Pathology - Laboratory of Neuropathology, Center of Biomedical Research, University of Ulm, Helmholtzstrasse 8/1, D-89081, Ulm, Germany.

ABSTRACT

Introduction: The deposition of the amyloid β protein (Aβ) in the brain is a hallmark of Alzheimer's disease (AD). Removal of Aβ by Aβ-antibody treatment has been developed as a potential treatment strategy against AD. First clinical trials showed neither a stop nor a reduction of disease progression. Recently, we have shown that the formation of soluble and insoluble Aβ aggregates in the human brain follows a hierarchical sequence of three biochemical maturation stages (B-Aβ stages). To test the impact of the B-Aβ stage on Aβ immunotherapy, we treated transgenic mice expressing human amyloid precursor protein (APP) carrying the Swedish mutation (KM670/671NL; APP23) with the Aβ-antibody β1 or phosphate-buffered saline (PBS) beginning 1) at 3 months, before the onset of dendrite degeneration and plaque deposition, and 2) at 7 months, after the start of Aβ plaque deposition and dendrite degeneration.

Results: At 5 months of age, first Aβ aggregates in APP23 brain consisted of non-modified Aβ (representing B-Aβ stage 1) whereas mature Aβ-aggregates containing N-terminal truncated, pyroglutamate-modified AβN3pE and phosphorylated Aβ (representing B-Aβ stage 3) were found at 11 months of age in both β1- and PBS-treated animals. Protective effects on commissural neurons with highly ramified dendritic trees were observed only in 3-month-old β1-treated animals sacrificed at 5 months. When treatment started at 7 months of age, no differences in the numbers of healthy commissural neurons were observed between β1- and PBS-treated APP23 mice sacrificed with 11 months.

Conclusions: Aβ antibody treatment was capable of protecting neurons from dendritic degeneration as long as Aβ aggregation was absent or represented B-Aβ stage 1 but had no protective or curative effect in later stages with mature Aβ aggregates (B-Aβ stage 3). These data indicate that the maturation stage of Aβ aggregates has impact on potential treatment effects in APP23 mice.

No MeSH data available.


Related in: MedlinePlus