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Breaking immune tolerance by targeting Foxp3(+) regulatory T cells mitigates Alzheimer's disease pathology.

Baruch K, Rosenzweig N, Kertser A, Deczkowska A, Sharif AM, Spinrad A, Tsitsou-Kampeli A, Sarel A, Cahalon L, Schwartz M - Nat Commun (2015)

Bottom Line: Nevertheless, while immunosuppressive drugs have repeatedly failed in treating this disease, recruitment of myeloid cells to the CNS was shown to play a reparative role in animal models.We further show that transient Treg depletion affects the brain's choroid plexus, a selective gateway for immune cell trafficking to the CNS, and is associated with subsequent recruitment of immunoregulatory cells, including monocyte-derived macrophages and Tregs, to cerebral sites of plaque pathology.Our findings suggest targeting Treg-mediated systemic immunosuppression for treating AD.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurobiology, Weizmann Institute of Science, 234 Herzl Street, Rehovot 76100, Israel.

ABSTRACT
Alzheimer's disease (AD) is a neurodegenerative disorder in which chronic neuroinflammation contributes to disease escalation. Nevertheless, while immunosuppressive drugs have repeatedly failed in treating this disease, recruitment of myeloid cells to the CNS was shown to play a reparative role in animal models. Here we show, using the 5XFAD AD mouse model, that transient depletion of Foxp3(+) regulatory T cells (Tregs), or pharmacological inhibition of their activity, is followed by amyloid-β plaque clearance, mitigation of the neuroinflammatory response and reversal of cognitive decline. We further show that transient Treg depletion affects the brain's choroid plexus, a selective gateway for immune cell trafficking to the CNS, and is associated with subsequent recruitment of immunoregulatory cells, including monocyte-derived macrophages and Tregs, to cerebral sites of plaque pathology. Our findings suggest targeting Treg-mediated systemic immunosuppression for treating AD.

No MeSH data available.


Related in: MedlinePlus

Immunomodulation that reduces systemic Treg levels activates the CP for mo-MΦ trafficking and mitigates AD pathology.(a) mRNA expression levels of ifn-γ, measured by RT-qPCR, in CPs isolated from 6- and 12-month-old APP/PS1 AD-Tg mice, compared with age-matched WT controls (n=5–8 per group; Student's t-test). (b,c) 5XFAD AD-Tg mice were treated with either weekly GA or vehicle (PBS), and were examined at the end of the 1st week of the administration regimen (after a total of two GA injections). Flow cytometry analysis of CD4+Foxp3+ splenocyte frequencies (b) and CP-resident IFN-γ-expressing immune cells (intracellularly stained and pre-gated on CD45) (c), in treated 6-month-old AD-Tg mice, compared with age-matched WT controls (n=4–6 per group; one-way ANOVA followed by Newman–Keuls post hoc analysis). (d) mRNA expression levels for the genes icam1, cxcl10 and ccl2, measured by RT-qPCR, in CPs of 4-month-old AD-Tg mice, treated with either weekly GA or vehicle, and examined either at the end of the 1st or 4th week of the weekly GA regimen (n=6–8 per group; one-way ANOVA followed by Newman–Keuls post hoc analysis). (e) Representative microscopic images of 6-month-old AD-Tg mice following weekly GA, stained for ICAM-1 (in red) and Claudin-1 (in green; epithelial tight junctions), showing elevated levels of ICAM-1 immunoreactivity, as compared with vehicle-treated AD-Tg (scale bar, 50 μm). (f) Representative images of brain sections from 6-month-old AD-Tg/CX3CR1GFP/+ BM chimeras following weekly GA. CX3CR1GFP cells were localized at the CP of the third ventricle (3V; i), the adjacent ventricular spaces (ii), and the CP of the lateral ventricles (LV; iii) in AD-Tg mice treated with weekly GA (scale bar, 25 μm). (g) Representative orthogonal projections of confocal z-axis stacks, showing co-localization of GFP+ cells (in green) with the myeloid marker, CD68 (in red), in the CP of 7-month-old AD-Tg/CX3CR1GFP/+ mice treated with weekly GA, but not in control PBS-treated AD-Tg/CX3CR1GFP/+ mice (scale bar, 25 μm). (h) CX3CR1GFP cells (in green) are co-localized with the myeloid marker IBA-1 in brains of GA-treated AD-Tg/CX3CR1GFP/+ mice in the vicinity of Aβ plaques, and co-express the myeloid marker, IBA-1 (in red). Arrowheads indicate co-labelled IBA-1+/GFP+ cells (scale bar, 25 μm). In all panels, error bars represent mean±s.e.m.; *P<0.05; **P<0.01; ***P<0.001.
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f3: Immunomodulation that reduces systemic Treg levels activates the CP for mo-MΦ trafficking and mitigates AD pathology.(a) mRNA expression levels of ifn-γ, measured by RT-qPCR, in CPs isolated from 6- and 12-month-old APP/PS1 AD-Tg mice, compared with age-matched WT controls (n=5–8 per group; Student's t-test). (b,c) 5XFAD AD-Tg mice were treated with either weekly GA or vehicle (PBS), and were examined at the end of the 1st week of the administration regimen (after a total of two GA injections). Flow cytometry analysis of CD4+Foxp3+ splenocyte frequencies (b) and CP-resident IFN-γ-expressing immune cells (intracellularly stained and pre-gated on CD45) (c), in treated 6-month-old AD-Tg mice, compared with age-matched WT controls (n=4–6 per group; one-way ANOVA followed by Newman–Keuls post hoc analysis). (d) mRNA expression levels for the genes icam1, cxcl10 and ccl2, measured by RT-qPCR, in CPs of 4-month-old AD-Tg mice, treated with either weekly GA or vehicle, and examined either at the end of the 1st or 4th week of the weekly GA regimen (n=6–8 per group; one-way ANOVA followed by Newman–Keuls post hoc analysis). (e) Representative microscopic images of 6-month-old AD-Tg mice following weekly GA, stained for ICAM-1 (in red) and Claudin-1 (in green; epithelial tight junctions), showing elevated levels of ICAM-1 immunoreactivity, as compared with vehicle-treated AD-Tg (scale bar, 50 μm). (f) Representative images of brain sections from 6-month-old AD-Tg/CX3CR1GFP/+ BM chimeras following weekly GA. CX3CR1GFP cells were localized at the CP of the third ventricle (3V; i), the adjacent ventricular spaces (ii), and the CP of the lateral ventricles (LV; iii) in AD-Tg mice treated with weekly GA (scale bar, 25 μm). (g) Representative orthogonal projections of confocal z-axis stacks, showing co-localization of GFP+ cells (in green) with the myeloid marker, CD68 (in red), in the CP of 7-month-old AD-Tg/CX3CR1GFP/+ mice treated with weekly GA, but not in control PBS-treated AD-Tg/CX3CR1GFP/+ mice (scale bar, 25 μm). (h) CX3CR1GFP cells (in green) are co-localized with the myeloid marker IBA-1 in brains of GA-treated AD-Tg/CX3CR1GFP/+ mice in the vicinity of Aβ plaques, and co-express the myeloid marker, IBA-1 (in red). Arrowheads indicate co-labelled IBA-1+/GFP+ cells (scale bar, 25 μm). In all panels, error bars represent mean±s.e.m.; *P<0.05; **P<0.01; ***P<0.001.

Mentions: We next-tested whether the immunomodulatory compound, glatiramer acetate (GA; also known as Copolymer-1 or Copaxone), which was found in a weekly administration regimen to have a therapeutic effect in the APP/PS1 mouse model of AD33, associated with mo-MΦ recruitment to cerebral sites of disease pathology1216, would induce CP activation to enhance leukocyte trafficking. We found that the CP in APP/PS1 AD-Tg mice expresses lower levels of IFN-γ relative to age-matched WT controls (Fig. 3a), similarly to our observation in the 5XFAD AD-Tg mouse model (Fig. 1f). These findings encouraged us to test whether the observed therapeutic effect of weekly administration of GA in APP/PS1 mice33 could be reproduced in 5XFAD AD-Tg mice, and if so, whether it would involve an effect on systemic Tregs and IFN-γ-activation of the CP for mo-MΦ trafficking. We therefore treated 5XFAD AD-Tg mice with a weekly administration regimen of GA over a period of 4 weeks (henceforth, ‘weekly GA'; schematically depicted in Supplementary Fig. 2a). We found that 5XFAD AD-Tg mice treated with weekly GA showed reduced neuroinflammation (Supplementary Fig. 2b,c), enhanced hippocampal expression of brain-derived neurotrophic factor (bdnf) and insulin-like growth factor-1 (igf1) (Supplementary Fig. 2d) and improved cognitive performance (Supplementary Fig. 2e–g), which lasted up to 2 months after the treatment (Supplementary Fig. 2h,i). Examining by flow cytometry the effect of weekly GA on systemic immunity and on the CP, we found reduced splenocyte Foxp3+ Treg levels (Fig. 3b), and an increase in IFN-γ-producing cells at the CP of the treated 5XFAD AD-Tg mice, reaching similar levels to those observed in WT controls (Fig. 3c). The elevated numbers of IFN-γ-expressing cells in the CP of weekly GA-treated mice correlated with the upregulated expression of leukocyte trafficking molecules by the CP (Fig. 3d). Immunohistochemical analysis of the CP, in the weekly GA-treated AD-Tg mice, confirmed increased levels of epithelial ICAM-1 (Fig. 3e), and showed altered epithelial tight junction organization (Supplementary Fig. 3a), previously associated with CNS-infiltrating mo-MΦ trafficking through the CP-CSF migratory pathway171820.


Breaking immune tolerance by targeting Foxp3(+) regulatory T cells mitigates Alzheimer's disease pathology.

Baruch K, Rosenzweig N, Kertser A, Deczkowska A, Sharif AM, Spinrad A, Tsitsou-Kampeli A, Sarel A, Cahalon L, Schwartz M - Nat Commun (2015)

Immunomodulation that reduces systemic Treg levels activates the CP for mo-MΦ trafficking and mitigates AD pathology.(a) mRNA expression levels of ifn-γ, measured by RT-qPCR, in CPs isolated from 6- and 12-month-old APP/PS1 AD-Tg mice, compared with age-matched WT controls (n=5–8 per group; Student's t-test). (b,c) 5XFAD AD-Tg mice were treated with either weekly GA or vehicle (PBS), and were examined at the end of the 1st week of the administration regimen (after a total of two GA injections). Flow cytometry analysis of CD4+Foxp3+ splenocyte frequencies (b) and CP-resident IFN-γ-expressing immune cells (intracellularly stained and pre-gated on CD45) (c), in treated 6-month-old AD-Tg mice, compared with age-matched WT controls (n=4–6 per group; one-way ANOVA followed by Newman–Keuls post hoc analysis). (d) mRNA expression levels for the genes icam1, cxcl10 and ccl2, measured by RT-qPCR, in CPs of 4-month-old AD-Tg mice, treated with either weekly GA or vehicle, and examined either at the end of the 1st or 4th week of the weekly GA regimen (n=6–8 per group; one-way ANOVA followed by Newman–Keuls post hoc analysis). (e) Representative microscopic images of 6-month-old AD-Tg mice following weekly GA, stained for ICAM-1 (in red) and Claudin-1 (in green; epithelial tight junctions), showing elevated levels of ICAM-1 immunoreactivity, as compared with vehicle-treated AD-Tg (scale bar, 50 μm). (f) Representative images of brain sections from 6-month-old AD-Tg/CX3CR1GFP/+ BM chimeras following weekly GA. CX3CR1GFP cells were localized at the CP of the third ventricle (3V; i), the adjacent ventricular spaces (ii), and the CP of the lateral ventricles (LV; iii) in AD-Tg mice treated with weekly GA (scale bar, 25 μm). (g) Representative orthogonal projections of confocal z-axis stacks, showing co-localization of GFP+ cells (in green) with the myeloid marker, CD68 (in red), in the CP of 7-month-old AD-Tg/CX3CR1GFP/+ mice treated with weekly GA, but not in control PBS-treated AD-Tg/CX3CR1GFP/+ mice (scale bar, 25 μm). (h) CX3CR1GFP cells (in green) are co-localized with the myeloid marker IBA-1 in brains of GA-treated AD-Tg/CX3CR1GFP/+ mice in the vicinity of Aβ plaques, and co-express the myeloid marker, IBA-1 (in red). Arrowheads indicate co-labelled IBA-1+/GFP+ cells (scale bar, 25 μm). In all panels, error bars represent mean±s.e.m.; *P<0.05; **P<0.01; ***P<0.001.
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f3: Immunomodulation that reduces systemic Treg levels activates the CP for mo-MΦ trafficking and mitigates AD pathology.(a) mRNA expression levels of ifn-γ, measured by RT-qPCR, in CPs isolated from 6- and 12-month-old APP/PS1 AD-Tg mice, compared with age-matched WT controls (n=5–8 per group; Student's t-test). (b,c) 5XFAD AD-Tg mice were treated with either weekly GA or vehicle (PBS), and were examined at the end of the 1st week of the administration regimen (after a total of two GA injections). Flow cytometry analysis of CD4+Foxp3+ splenocyte frequencies (b) and CP-resident IFN-γ-expressing immune cells (intracellularly stained and pre-gated on CD45) (c), in treated 6-month-old AD-Tg mice, compared with age-matched WT controls (n=4–6 per group; one-way ANOVA followed by Newman–Keuls post hoc analysis). (d) mRNA expression levels for the genes icam1, cxcl10 and ccl2, measured by RT-qPCR, in CPs of 4-month-old AD-Tg mice, treated with either weekly GA or vehicle, and examined either at the end of the 1st or 4th week of the weekly GA regimen (n=6–8 per group; one-way ANOVA followed by Newman–Keuls post hoc analysis). (e) Representative microscopic images of 6-month-old AD-Tg mice following weekly GA, stained for ICAM-1 (in red) and Claudin-1 (in green; epithelial tight junctions), showing elevated levels of ICAM-1 immunoreactivity, as compared with vehicle-treated AD-Tg (scale bar, 50 μm). (f) Representative images of brain sections from 6-month-old AD-Tg/CX3CR1GFP/+ BM chimeras following weekly GA. CX3CR1GFP cells were localized at the CP of the third ventricle (3V; i), the adjacent ventricular spaces (ii), and the CP of the lateral ventricles (LV; iii) in AD-Tg mice treated with weekly GA (scale bar, 25 μm). (g) Representative orthogonal projections of confocal z-axis stacks, showing co-localization of GFP+ cells (in green) with the myeloid marker, CD68 (in red), in the CP of 7-month-old AD-Tg/CX3CR1GFP/+ mice treated with weekly GA, but not in control PBS-treated AD-Tg/CX3CR1GFP/+ mice (scale bar, 25 μm). (h) CX3CR1GFP cells (in green) are co-localized with the myeloid marker IBA-1 in brains of GA-treated AD-Tg/CX3CR1GFP/+ mice in the vicinity of Aβ plaques, and co-express the myeloid marker, IBA-1 (in red). Arrowheads indicate co-labelled IBA-1+/GFP+ cells (scale bar, 25 μm). In all panels, error bars represent mean±s.e.m.; *P<0.05; **P<0.01; ***P<0.001.
Mentions: We next-tested whether the immunomodulatory compound, glatiramer acetate (GA; also known as Copolymer-1 or Copaxone), which was found in a weekly administration regimen to have a therapeutic effect in the APP/PS1 mouse model of AD33, associated with mo-MΦ recruitment to cerebral sites of disease pathology1216, would induce CP activation to enhance leukocyte trafficking. We found that the CP in APP/PS1 AD-Tg mice expresses lower levels of IFN-γ relative to age-matched WT controls (Fig. 3a), similarly to our observation in the 5XFAD AD-Tg mouse model (Fig. 1f). These findings encouraged us to test whether the observed therapeutic effect of weekly administration of GA in APP/PS1 mice33 could be reproduced in 5XFAD AD-Tg mice, and if so, whether it would involve an effect on systemic Tregs and IFN-γ-activation of the CP for mo-MΦ trafficking. We therefore treated 5XFAD AD-Tg mice with a weekly administration regimen of GA over a period of 4 weeks (henceforth, ‘weekly GA'; schematically depicted in Supplementary Fig. 2a). We found that 5XFAD AD-Tg mice treated with weekly GA showed reduced neuroinflammation (Supplementary Fig. 2b,c), enhanced hippocampal expression of brain-derived neurotrophic factor (bdnf) and insulin-like growth factor-1 (igf1) (Supplementary Fig. 2d) and improved cognitive performance (Supplementary Fig. 2e–g), which lasted up to 2 months after the treatment (Supplementary Fig. 2h,i). Examining by flow cytometry the effect of weekly GA on systemic immunity and on the CP, we found reduced splenocyte Foxp3+ Treg levels (Fig. 3b), and an increase in IFN-γ-producing cells at the CP of the treated 5XFAD AD-Tg mice, reaching similar levels to those observed in WT controls (Fig. 3c). The elevated numbers of IFN-γ-expressing cells in the CP of weekly GA-treated mice correlated with the upregulated expression of leukocyte trafficking molecules by the CP (Fig. 3d). Immunohistochemical analysis of the CP, in the weekly GA-treated AD-Tg mice, confirmed increased levels of epithelial ICAM-1 (Fig. 3e), and showed altered epithelial tight junction organization (Supplementary Fig. 3a), previously associated with CNS-infiltrating mo-MΦ trafficking through the CP-CSF migratory pathway171820.

Bottom Line: Nevertheless, while immunosuppressive drugs have repeatedly failed in treating this disease, recruitment of myeloid cells to the CNS was shown to play a reparative role in animal models.We further show that transient Treg depletion affects the brain's choroid plexus, a selective gateway for immune cell trafficking to the CNS, and is associated with subsequent recruitment of immunoregulatory cells, including monocyte-derived macrophages and Tregs, to cerebral sites of plaque pathology.Our findings suggest targeting Treg-mediated systemic immunosuppression for treating AD.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurobiology, Weizmann Institute of Science, 234 Herzl Street, Rehovot 76100, Israel.

ABSTRACT
Alzheimer's disease (AD) is a neurodegenerative disorder in which chronic neuroinflammation contributes to disease escalation. Nevertheless, while immunosuppressive drugs have repeatedly failed in treating this disease, recruitment of myeloid cells to the CNS was shown to play a reparative role in animal models. Here we show, using the 5XFAD AD mouse model, that transient depletion of Foxp3(+) regulatory T cells (Tregs), or pharmacological inhibition of their activity, is followed by amyloid-β plaque clearance, mitigation of the neuroinflammatory response and reversal of cognitive decline. We further show that transient Treg depletion affects the brain's choroid plexus, a selective gateway for immune cell trafficking to the CNS, and is associated with subsequent recruitment of immunoregulatory cells, including monocyte-derived macrophages and Tregs, to cerebral sites of plaque pathology. Our findings suggest targeting Treg-mediated systemic immunosuppression for treating AD.

No MeSH data available.


Related in: MedlinePlus