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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

The type-1 IFN and pro-inflammatory cytokine response to Aβ1-42 is attenuated upon removal of IFNAR1 in primary cultured glia. a Q-PCR of primary wildtype and IFNAR1−/− glial cultures treated with 10 μM Aβ1-42 for 24–96 h analyzing IFNα, IFNβ, IL-1β, IL-6 and TNFα transcript levels. b Representative immunoblot of primary wildtype and IFNAR1−/− glial cultures treated with 10 μM Aβ1-42 for 24–72 h using anti-p-NFkB (p65). c Densitometry of p-NFkB (p65) levels in primary wildtype and IFNAR1−/− glial cultures treated with 10 μM Aβ1-42 for 24–72 h. For Q-PCR all samples were normalized back to the Ct value of the housekeeping gene GAPDH (ΔCt). The mRNA of the Aβ1-42 treatment groups was then expressed relative to their gene-specific vehicle controls (fold change, ∆∆Ct). For densitometry raw intensities of p-NFkB (p65) bands were normalized to β-actin levels. All intensity values of Aβ1-42 treated groups are expressed as fold change relative to the genotype-specific vehicle control (average of which is represented by the dashed line). Immunodetection of β-actin was used to ascertain loading quantities. Data are displayed as mean ± SEM (Q-PCR: n = 4 (wildtype), n = 5 (IFNAR1−/−); Western blotting: n = 3 per genotype; *p < 0.05, **p < 0.01, ***p < 0.001, ****p < 0.0001). See Additional file 2: Table S1 for further analysis
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Fig6: The type-1 IFN and pro-inflammatory cytokine response to Aβ1-42 is attenuated upon removal of IFNAR1 in primary cultured glia. a Q-PCR of primary wildtype and IFNAR1−/− glial cultures treated with 10 μM Aβ1-42 for 24–96 h analyzing IFNα, IFNβ, IL-1β, IL-6 and TNFα transcript levels. b Representative immunoblot of primary wildtype and IFNAR1−/− glial cultures treated with 10 μM Aβ1-42 for 24–72 h using anti-p-NFkB (p65). c Densitometry of p-NFkB (p65) levels in primary wildtype and IFNAR1−/− glial cultures treated with 10 μM Aβ1-42 for 24–72 h. For Q-PCR all samples were normalized back to the Ct value of the housekeeping gene GAPDH (ΔCt). The mRNA of the Aβ1-42 treatment groups was then expressed relative to their gene-specific vehicle controls (fold change, ∆∆Ct). For densitometry raw intensities of p-NFkB (p65) bands were normalized to β-actin levels. All intensity values of Aβ1-42 treated groups are expressed as fold change relative to the genotype-specific vehicle control (average of which is represented by the dashed line). Immunodetection of β-actin was used to ascertain loading quantities. Data are displayed as mean ± SEM (Q-PCR: n = 4 (wildtype), n = 5 (IFNAR1−/−); Western blotting: n = 3 per genotype; *p < 0.05, **p < 0.01, ***p < 0.001, ****p < 0.0001). See Additional file 2: Table S1 for further analysis

Mentions: Astrocytes and microglia are key contributors to the inflammatory phenotype in AD and are also sources of type-1 IFN production within the CNS [51]. To investigate the role of astroglial and microglial type-1 IFN production in response to Aβ1-42, the predominant Aβ species over-produced in APPSWE/PS1ΔE9 mice [30, 31], we adopted an in vitro approach using primary cultured mixed glial cultures. Wildtype and IFNAR1−/− glia were treated with 10 μM Aβ1-42 for 24–96 h and Q-PCR was used to assess IFNα and IFNβ expression. At 72 and 96 h post-treatment IFNAR1−/− glia displayed reduced IFNα (72 h: Wildtype: 12.7 ± 1.8-fold vs. IFNAR1−/−: 1.4 ± 0.1-fold, p < 0.0001; 96 h: Wildtype: 9.1 ± 4.4-fold vs. IFNAR1−/−: 1.3 ± 0.2-fold, p = 0.0007, n = 4–5 per genotype, Fig. 6a) and IFNβ expression (72 h: Wildtype: 6.4 ± 1.3-fold vs. IFNAR1−/−: 0.7 ± 0.2-fold, p = 0.0006; 96 h: Wildtype: 6.3 ± 2.1-fold vs. IFNAR1−/−: 0.9 ± 0.3-fold, p = 0.0012, n = 4–5 per genotype, Fig. 6a) compared to wildtype cultures. In contrast to our in vivo data, Western blotting and subsequent densitometry revealed that Aβ1-42 treatment did not induce a p-Stat-3 response in either wildtype or IFNAR1−/− glial cultures, displaying a comparable expression level (Additional file 4: Figure S3). Overall these findings identify a glial-derived type-1 IFN response to Aβ1-42. Furthermore this type-1 IFN response is attenuated upon removal of IFNAR1, in line with the notion that IFNAR1 is critical in autocrine up-regulation of type-1 IFNs in response to inflammatory stimuli [13, 29].Fig. 6


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)

The type-1 IFN and pro-inflammatory cytokine response to Aβ1-42 is attenuated upon removal of IFNAR1 in primary cultured glia. a Q-PCR of primary wildtype and IFNAR1−/− glial cultures treated with 10 μM Aβ1-42 for 24–96 h analyzing IFNα, IFNβ, IL-1β, IL-6 and TNFα transcript levels. b Representative immunoblot of primary wildtype and IFNAR1−/− glial cultures treated with 10 μM Aβ1-42 for 24–72 h using anti-p-NFkB (p65). c Densitometry of p-NFkB (p65) levels in primary wildtype and IFNAR1−/− glial cultures treated with 10 μM Aβ1-42 for 24–72 h. For Q-PCR all samples were normalized back to the Ct value of the housekeeping gene GAPDH (ΔCt). The mRNA of the Aβ1-42 treatment groups was then expressed relative to their gene-specific vehicle controls (fold change, ∆∆Ct). For densitometry raw intensities of p-NFkB (p65) bands were normalized to β-actin levels. All intensity values of Aβ1-42 treated groups are expressed as fold change relative to the genotype-specific vehicle control (average of which is represented by the dashed line). Immunodetection of β-actin was used to ascertain loading quantities. Data are displayed as mean ± SEM (Q-PCR: n = 4 (wildtype), n = 5 (IFNAR1−/−); Western blotting: n = 3 per genotype; *p < 0.05, **p < 0.01, ***p < 0.001, ****p < 0.0001). See Additional file 2: Table S1 for further analysis
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Fig6: The type-1 IFN and pro-inflammatory cytokine response to Aβ1-42 is attenuated upon removal of IFNAR1 in primary cultured glia. a Q-PCR of primary wildtype and IFNAR1−/− glial cultures treated with 10 μM Aβ1-42 for 24–96 h analyzing IFNα, IFNβ, IL-1β, IL-6 and TNFα transcript levels. b Representative immunoblot of primary wildtype and IFNAR1−/− glial cultures treated with 10 μM Aβ1-42 for 24–72 h using anti-p-NFkB (p65). c Densitometry of p-NFkB (p65) levels in primary wildtype and IFNAR1−/− glial cultures treated with 10 μM Aβ1-42 for 24–72 h. For Q-PCR all samples were normalized back to the Ct value of the housekeeping gene GAPDH (ΔCt). The mRNA of the Aβ1-42 treatment groups was then expressed relative to their gene-specific vehicle controls (fold change, ∆∆Ct). For densitometry raw intensities of p-NFkB (p65) bands were normalized to β-actin levels. All intensity values of Aβ1-42 treated groups are expressed as fold change relative to the genotype-specific vehicle control (average of which is represented by the dashed line). Immunodetection of β-actin was used to ascertain loading quantities. Data are displayed as mean ± SEM (Q-PCR: n = 4 (wildtype), n = 5 (IFNAR1−/−); Western blotting: n = 3 per genotype; *p < 0.05, **p < 0.01, ***p < 0.001, ****p < 0.0001). See Additional file 2: Table S1 for further analysis
Mentions: Astrocytes and microglia are key contributors to the inflammatory phenotype in AD and are also sources of type-1 IFN production within the CNS [51]. To investigate the role of astroglial and microglial type-1 IFN production in response to Aβ1-42, the predominant Aβ species over-produced in APPSWE/PS1ΔE9 mice [30, 31], we adopted an in vitro approach using primary cultured mixed glial cultures. Wildtype and IFNAR1−/− glia were treated with 10 μM Aβ1-42 for 24–96 h and Q-PCR was used to assess IFNα and IFNβ expression. At 72 and 96 h post-treatment IFNAR1−/− glia displayed reduced IFNα (72 h: Wildtype: 12.7 ± 1.8-fold vs. IFNAR1−/−: 1.4 ± 0.1-fold, p < 0.0001; 96 h: Wildtype: 9.1 ± 4.4-fold vs. IFNAR1−/−: 1.3 ± 0.2-fold, p = 0.0007, n = 4–5 per genotype, Fig. 6a) and IFNβ expression (72 h: Wildtype: 6.4 ± 1.3-fold vs. IFNAR1−/−: 0.7 ± 0.2-fold, p = 0.0006; 96 h: Wildtype: 6.3 ± 2.1-fold vs. IFNAR1−/−: 0.9 ± 0.3-fold, p = 0.0012, n = 4–5 per genotype, Fig. 6a) compared to wildtype cultures. In contrast to our in vivo data, Western blotting and subsequent densitometry revealed that Aβ1-42 treatment did not induce a p-Stat-3 response in either wildtype or IFNAR1−/− glial cultures, displaying a comparable expression level (Additional file 4: Figure S3). Overall these findings identify a glial-derived type-1 IFN response to Aβ1-42. Furthermore this type-1 IFN response is attenuated upon removal of IFNAR1, in line with the notion that IFNAR1 is critical in autocrine up-regulation of type-1 IFNs in response to inflammatory stimuli [13, 29].Fig. 6

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