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Deletion of the type-1 interferon receptor in APPSWE/PS1ΔE9 mice preserves cognitive function and alters glial phenotype.

Minter MR, Moore Z, Zhang M, Brody KM, Jones NC, Shultz SR, Taylor JM, Crack PJ - Acta Neuropathol Commun (2016)

Bottom Line: A neuro-inflammatory response is evident in Alzheimer's disease (AD), yet the precise mechanisms by which neuro-inflammation influences the progression of Alzheimer's disease (AD) remain poorly understood.These APPSWE/PS1ΔE9 x IFNAR1(-/-) microglial populations demonstrated an anti-inflammatory phenotype that was confirmed in vitro by soluble Aβ1-42 treatment of IFNAR1(-/-) primary glial cultures.Our findings suggest that modulating neuro-inflammatory responses by suppressing type-1 IFN signaling may provide therapeutic benefit in AD.

View Article: PubMed Central - PubMed

Affiliation: Department of Pharmacology and Therapeutics, University of Melbourne, 8th floor, Medical building, Grattan St, Parkville, Melbourne, 3010, Victoria, Australia.

ABSTRACT
A neuro-inflammatory response is evident in Alzheimer's disease (AD), yet the precise mechanisms by which neuro-inflammation influences the progression of Alzheimer's disease (AD) remain poorly understood. Type-1 interferons (IFNs) are master regulators of innate immunity and have been implicated in multiple CNS disorders, however their role in AD progression has not yet been fully investigated. Hence, we generated APPSWE/PS1ΔE9 mice lacking the type-1 IFN alpha receptor-1 (IFNAR1, APPSWE/PS1ΔE9 x IFNAR1(-/-)) aged to 9 months to investigate the role of type-1 IFN signaling in a well-validated model of AD. APPSWE/PS1ΔE9 x IFNAR1(-/-) mice displayed a modest reduction in Aβ monomer levels, despite maintenance of plaque deposition. This finding correlated with partial rescue of spatial learning and memory impairments in the Morris water maze in comparison to APPSWE/PS1ΔE9 mice. Q-PCR identified a reduced type-1 IFN response and modulated pro-inflammatory cytokine secretion in APPSWE/PS1ΔE9 x IFNAR1(-/-) mice compared to APPSWE/PS1ΔE9 mice. Interestingly, immunohistochemistry displayed enhanced astrocyte reactivity but attenuated microgliosis surrounding amyloid plaque deposits in APPSWE/PS1ΔE9 x IFNAR1(-/-) mice in comparison to APPSWE/PS1ΔE9 mice. These APPSWE/PS1ΔE9 x IFNAR1(-/-) microglial populations demonstrated an anti-inflammatory phenotype that was confirmed in vitro by soluble Aβ1-42 treatment of IFNAR1(-/-) primary glial cultures. Our findings suggest that modulating neuro-inflammatory responses by suppressing type-1 IFN signaling may provide therapeutic benefit in AD.

No MeSH data available.


Related in: MedlinePlus

Removal of IFNAR1 in APPSWE/PS1ΔE9 mice confers modest reductions in Aβ monomer levels but not plaque burden. Representative cortical sections from 9 month old a APPSWE/PS1ΔE9 and b APPSWE/PS1ΔE9 x IFNAR1−/− mice stained with anti-Aβ mAb WO-2 using fluorescence immunohistochemistry (scale bar = 200 μm). c Aβ plaques were counted from entire cortical regions of APPSWE/PS1ΔE9 and APPSWE/PS1ΔE9 x IFNAR1−/− mice (3 sections per mouse, •represents outlier value). d Cortical plaque burden was calculated by quantifying Aβ plaque immunofluorescence relative to total cortical area from these same cortical slices of APPSWE/PS1ΔE9 and APPSWE/PS1ΔE9 x IFNAR1−/− mice. e PBS-T-soluble and f PBS-T-insoluble Aβ1:40 levels in APPSWE/PS1ΔE9 and APPSWE/PS1ΔE9 x IFNAR1−/− mouse cortical lysates were quantified by ELISA. g Representative immunoblot of Tris–HCl soluble cortical protein lysates isolated from 9 month old wildtype, IFNAR1−/−, APPSWE/PS1ΔE9 and APPSWE/PS1ΔE9 x IFNAR1−/− mice using the anti-Aβ mAb WO-2. Multiple amyloid species can be detected including endogenous APP-CTF (muAPP-CTF), transgenic APP-CTF (TgAPP-CTF), Aβ trimers (3-mer) and Aβ monomers. A long exposure (LE) was used to enhance detection of Aβ monomer levels. Densitometry of h Transgenic APP-CTF, i endogenous murine APP-CTF, j Aβ monomer and k 3-mer levels in APPSWE/PS1ΔE9 and APPSWE/PS1ΔE9 x IFNAR1−/− mice is shown. All densitometry is expressed as a ratio of Aβ monomer:β-actin or Aβ trimer:β-actin raw pixel intensities. Immuno-detection of β-actin was used to ascertain loading quantities. Data is presented as box plots described in the statistical analysis section in Materials and Methods (immunohistochemistry: n = 9 per genotype; ELISA and Western blotting: n = 6 (APPSWE/PS1ΔE9), n = 4 (APPSWE/PS1ΔE9 x IFNAR1−/−); *p < 0.05, ****p < 0.0001). See Additional file 2: Table S1 for further analysis
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Fig1: Removal of IFNAR1 in APPSWE/PS1ΔE9 mice confers modest reductions in Aβ monomer levels but not plaque burden. Representative cortical sections from 9 month old a APPSWE/PS1ΔE9 and b APPSWE/PS1ΔE9 x IFNAR1−/− mice stained with anti-Aβ mAb WO-2 using fluorescence immunohistochemistry (scale bar = 200 μm). c Aβ plaques were counted from entire cortical regions of APPSWE/PS1ΔE9 and APPSWE/PS1ΔE9 x IFNAR1−/− mice (3 sections per mouse, •represents outlier value). d Cortical plaque burden was calculated by quantifying Aβ plaque immunofluorescence relative to total cortical area from these same cortical slices of APPSWE/PS1ΔE9 and APPSWE/PS1ΔE9 x IFNAR1−/− mice. e PBS-T-soluble and f PBS-T-insoluble Aβ1:40 levels in APPSWE/PS1ΔE9 and APPSWE/PS1ΔE9 x IFNAR1−/− mouse cortical lysates were quantified by ELISA. g Representative immunoblot of Tris–HCl soluble cortical protein lysates isolated from 9 month old wildtype, IFNAR1−/−, APPSWE/PS1ΔE9 and APPSWE/PS1ΔE9 x IFNAR1−/− mice using the anti-Aβ mAb WO-2. Multiple amyloid species can be detected including endogenous APP-CTF (muAPP-CTF), transgenic APP-CTF (TgAPP-CTF), Aβ trimers (3-mer) and Aβ monomers. A long exposure (LE) was used to enhance detection of Aβ monomer levels. Densitometry of h Transgenic APP-CTF, i endogenous murine APP-CTF, j Aβ monomer and k 3-mer levels in APPSWE/PS1ΔE9 and APPSWE/PS1ΔE9 x IFNAR1−/− mice is shown. All densitometry is expressed as a ratio of Aβ monomer:β-actin or Aβ trimer:β-actin raw pixel intensities. Immuno-detection of β-actin was used to ascertain loading quantities. Data is presented as box plots described in the statistical analysis section in Materials and Methods (immunohistochemistry: n = 9 per genotype; ELISA and Western blotting: n = 6 (APPSWE/PS1ΔE9), n = 4 (APPSWE/PS1ΔE9 x IFNAR1−/−); *p < 0.05, ****p < 0.0001). See Additional file 2: Table S1 for further analysis

Mentions: To investigate the effect of removing type-1 IFN signaling in AD we generated APPSWE/PS1ΔE9 x IFNAR1−/−. APPSWE/PS1ΔE9 mice aged 9 months display an enhanced type-1 IFN and pro-inflammatory cytokine response [64]. Hence, we focused on characterizing phenotypic alterations in APPSWE/PS1ΔE9 x IFNAR1−/− mice at this age. With variable hippocampal Aβ plaque deposition at this age in both APPSWE/PS1ΔE9 and APPSWE/PS1ΔE9 x IFNAR1−/− mice (data not shown), the current study focused on cortical regions only, not hippocampus. To assess potential alterations in Aβ plaque burden, immunohistochemistry was performed on APPSWE/PS1ΔE9 and APPSWE/PS1ΔE9 x IFNAR1−/− mouse brain sagittal sections, stained with anti-Aβ mAb WO-2 (n = 9 per genotype, Fig. 1a, b). Both APPSWE/PS1ΔE9 and APPSWE/PS1ΔE9 x IFNAR1−/− mice display extensive plaque deposition within cortical regions but no difference was detected between genotypes when Aβ plaques were counted (n = 9 per genotype, Fig. 1c) or when cortical plaque burden percentage was quantified (n = 9 per genotype, Fig. 1d). To validate these immunohistochemical findings we prepared PBS-T-soluble and PBS-T-insoluble fractions from cortical tissue to quantify Aβ levels by ELISA. We did not observe any differences in PBS-T-soluble or PBS-T-insoluble Aβ1:40 levels measured from cortical tissue lysates of APPSWE/PS1ΔE9 and APPSWE/PS1ΔE9 x IFNAR1−/− mice (n = 4–6 per genotype, Fig. 1e, d). These findings suggest that removal of type-1 IFN signaling in APPSWE/PS1ΔE9 mice does not influence amyloid plaque deposition at 9 months of age.Fig. 1


Deletion of the type-1 interferon receptor in APPSWE/PS1ΔE9 mice preserves cognitive function and alters glial phenotype.

Minter MR, Moore Z, Zhang M, Brody KM, Jones NC, Shultz SR, Taylor JM, Crack PJ - Acta Neuropathol Commun (2016)

Removal of IFNAR1 in APPSWE/PS1ΔE9 mice confers modest reductions in Aβ monomer levels but not plaque burden. Representative cortical sections from 9 month old a APPSWE/PS1ΔE9 and b APPSWE/PS1ΔE9 x IFNAR1−/− mice stained with anti-Aβ mAb WO-2 using fluorescence immunohistochemistry (scale bar = 200 μm). c Aβ plaques were counted from entire cortical regions of APPSWE/PS1ΔE9 and APPSWE/PS1ΔE9 x IFNAR1−/− mice (3 sections per mouse, •represents outlier value). d Cortical plaque burden was calculated by quantifying Aβ plaque immunofluorescence relative to total cortical area from these same cortical slices of APPSWE/PS1ΔE9 and APPSWE/PS1ΔE9 x IFNAR1−/− mice. e PBS-T-soluble and f PBS-T-insoluble Aβ1:40 levels in APPSWE/PS1ΔE9 and APPSWE/PS1ΔE9 x IFNAR1−/− mouse cortical lysates were quantified by ELISA. g Representative immunoblot of Tris–HCl soluble cortical protein lysates isolated from 9 month old wildtype, IFNAR1−/−, APPSWE/PS1ΔE9 and APPSWE/PS1ΔE9 x IFNAR1−/− mice using the anti-Aβ mAb WO-2. Multiple amyloid species can be detected including endogenous APP-CTF (muAPP-CTF), transgenic APP-CTF (TgAPP-CTF), Aβ trimers (3-mer) and Aβ monomers. A long exposure (LE) was used to enhance detection of Aβ monomer levels. Densitometry of h Transgenic APP-CTF, i endogenous murine APP-CTF, j Aβ monomer and k 3-mer levels in APPSWE/PS1ΔE9 and APPSWE/PS1ΔE9 x IFNAR1−/− mice is shown. All densitometry is expressed as a ratio of Aβ monomer:β-actin or Aβ trimer:β-actin raw pixel intensities. Immuno-detection of β-actin was used to ascertain loading quantities. Data is presented as box plots described in the statistical analysis section in Materials and Methods (immunohistochemistry: n = 9 per genotype; ELISA and Western blotting: n = 6 (APPSWE/PS1ΔE9), n = 4 (APPSWE/PS1ΔE9 x IFNAR1−/−); *p < 0.05, ****p < 0.0001). See Additional file 2: Table S1 for further analysis
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Fig1: Removal of IFNAR1 in APPSWE/PS1ΔE9 mice confers modest reductions in Aβ monomer levels but not plaque burden. Representative cortical sections from 9 month old a APPSWE/PS1ΔE9 and b APPSWE/PS1ΔE9 x IFNAR1−/− mice stained with anti-Aβ mAb WO-2 using fluorescence immunohistochemistry (scale bar = 200 μm). c Aβ plaques were counted from entire cortical regions of APPSWE/PS1ΔE9 and APPSWE/PS1ΔE9 x IFNAR1−/− mice (3 sections per mouse, •represents outlier value). d Cortical plaque burden was calculated by quantifying Aβ plaque immunofluorescence relative to total cortical area from these same cortical slices of APPSWE/PS1ΔE9 and APPSWE/PS1ΔE9 x IFNAR1−/− mice. e PBS-T-soluble and f PBS-T-insoluble Aβ1:40 levels in APPSWE/PS1ΔE9 and APPSWE/PS1ΔE9 x IFNAR1−/− mouse cortical lysates were quantified by ELISA. g Representative immunoblot of Tris–HCl soluble cortical protein lysates isolated from 9 month old wildtype, IFNAR1−/−, APPSWE/PS1ΔE9 and APPSWE/PS1ΔE9 x IFNAR1−/− mice using the anti-Aβ mAb WO-2. Multiple amyloid species can be detected including endogenous APP-CTF (muAPP-CTF), transgenic APP-CTF (TgAPP-CTF), Aβ trimers (3-mer) and Aβ monomers. A long exposure (LE) was used to enhance detection of Aβ monomer levels. Densitometry of h Transgenic APP-CTF, i endogenous murine APP-CTF, j Aβ monomer and k 3-mer levels in APPSWE/PS1ΔE9 and APPSWE/PS1ΔE9 x IFNAR1−/− mice is shown. All densitometry is expressed as a ratio of Aβ monomer:β-actin or Aβ trimer:β-actin raw pixel intensities. Immuno-detection of β-actin was used to ascertain loading quantities. Data is presented as box plots described in the statistical analysis section in Materials and Methods (immunohistochemistry: n = 9 per genotype; ELISA and Western blotting: n = 6 (APPSWE/PS1ΔE9), n = 4 (APPSWE/PS1ΔE9 x IFNAR1−/−); *p < 0.05, ****p < 0.0001). See Additional file 2: Table S1 for further analysis
Mentions: To investigate the effect of removing type-1 IFN signaling in AD we generated APPSWE/PS1ΔE9 x IFNAR1−/−. APPSWE/PS1ΔE9 mice aged 9 months display an enhanced type-1 IFN and pro-inflammatory cytokine response [64]. Hence, we focused on characterizing phenotypic alterations in APPSWE/PS1ΔE9 x IFNAR1−/− mice at this age. With variable hippocampal Aβ plaque deposition at this age in both APPSWE/PS1ΔE9 and APPSWE/PS1ΔE9 x IFNAR1−/− mice (data not shown), the current study focused on cortical regions only, not hippocampus. To assess potential alterations in Aβ plaque burden, immunohistochemistry was performed on APPSWE/PS1ΔE9 and APPSWE/PS1ΔE9 x IFNAR1−/− mouse brain sagittal sections, stained with anti-Aβ mAb WO-2 (n = 9 per genotype, Fig. 1a, b). Both APPSWE/PS1ΔE9 and APPSWE/PS1ΔE9 x IFNAR1−/− mice display extensive plaque deposition within cortical regions but no difference was detected between genotypes when Aβ plaques were counted (n = 9 per genotype, Fig. 1c) or when cortical plaque burden percentage was quantified (n = 9 per genotype, Fig. 1d). To validate these immunohistochemical findings we prepared PBS-T-soluble and PBS-T-insoluble fractions from cortical tissue to quantify Aβ levels by ELISA. We did not observe any differences in PBS-T-soluble or PBS-T-insoluble Aβ1:40 levels measured from cortical tissue lysates of APPSWE/PS1ΔE9 and APPSWE/PS1ΔE9 x IFNAR1−/− mice (n = 4–6 per genotype, Fig. 1e, d). These findings suggest that removal of type-1 IFN signaling in APPSWE/PS1ΔE9 mice does not influence amyloid plaque deposition at 9 months of age.Fig. 1

Bottom Line: A neuro-inflammatory response is evident in Alzheimer's disease (AD), yet the precise mechanisms by which neuro-inflammation influences the progression of Alzheimer's disease (AD) remain poorly understood.These APPSWE/PS1ΔE9 x IFNAR1(-/-) microglial populations demonstrated an anti-inflammatory phenotype that was confirmed in vitro by soluble Aβ1-42 treatment of IFNAR1(-/-) primary glial cultures.Our findings suggest that modulating neuro-inflammatory responses by suppressing type-1 IFN signaling may provide therapeutic benefit in AD.

View Article: PubMed Central - PubMed

Affiliation: Department of Pharmacology and Therapeutics, University of Melbourne, 8th floor, Medical building, Grattan St, Parkville, Melbourne, 3010, Victoria, Australia.

ABSTRACT
A neuro-inflammatory response is evident in Alzheimer's disease (AD), yet the precise mechanisms by which neuro-inflammation influences the progression of Alzheimer's disease (AD) remain poorly understood. Type-1 interferons (IFNs) are master regulators of innate immunity and have been implicated in multiple CNS disorders, however their role in AD progression has not yet been fully investigated. Hence, we generated APPSWE/PS1ΔE9 mice lacking the type-1 IFN alpha receptor-1 (IFNAR1, APPSWE/PS1ΔE9 x IFNAR1(-/-)) aged to 9 months to investigate the role of type-1 IFN signaling in a well-validated model of AD. APPSWE/PS1ΔE9 x IFNAR1(-/-) mice displayed a modest reduction in Aβ monomer levels, despite maintenance of plaque deposition. This finding correlated with partial rescue of spatial learning and memory impairments in the Morris water maze in comparison to APPSWE/PS1ΔE9 mice. Q-PCR identified a reduced type-1 IFN response and modulated pro-inflammatory cytokine secretion in APPSWE/PS1ΔE9 x IFNAR1(-/-) mice compared to APPSWE/PS1ΔE9 mice. Interestingly, immunohistochemistry displayed enhanced astrocyte reactivity but attenuated microgliosis surrounding amyloid plaque deposits in APPSWE/PS1ΔE9 x IFNAR1(-/-) mice in comparison to APPSWE/PS1ΔE9 mice. These APPSWE/PS1ΔE9 x IFNAR1(-/-) microglial populations demonstrated an anti-inflammatory phenotype that was confirmed in vitro by soluble Aβ1-42 treatment of IFNAR1(-/-) primary glial cultures. Our findings suggest that modulating neuro-inflammatory responses by suppressing type-1 IFN signaling may provide therapeutic benefit in AD.

No MeSH data available.


Related in: MedlinePlus