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Suppressed retinal degeneration in aged wild type and APPswe/PS1ΔE9 mice by bone marrow transplantation.

Yang Y, Shiao C, Hemingway JF, Jorstad NL, Shalloway BR, Chang R, Keene CD - PLoS ONE (2013)

Bottom Line: BMT resulted in near complete replacement of host retinal microglia with BMT-derived cells and normalized total AD retinal microglia to non-transplanted wt levels.Interestingly, aged wt BMT recipients also had significantly more neurons (25.4%) compared with non-transplanted aged wt controls.We found increased MHC class II expression in BMT-derived microglia and decreased oxidative damage in retinal ganglion cell layer neurons.

View Article: PubMed Central - PubMed

Affiliation: Department of Pathology, University of Washington, Seattle, Washington, USA.

ABSTRACT
Alzheimer's disease (AD) is an age-related condition characterized by accumulation of neurotoxic amyloid β peptides (Aβ) in brain and retina. Because bone marrow transplantation (BMT) results in decreased cerebral Aβ in experimental AD, we hypothesized that BMT would mitigate retinal neurotoxicity through decreased retinal Aβ. To test this, we performed BMT in APPswe/PS1ΔE9 double transgenic mice using green fluorescent protein expressing wild type (wt) mice as marrow donors. We first examined retinas from control, non-transplanted, aged AD mice and found a two-fold increase in microglia compared with wt mice, prominent inner retinal Aβ and paired helical filament-tau, and decreased retinal ganglion cell layer neurons. BMT resulted in near complete replacement of host retinal microglia with BMT-derived cells and normalized total AD retinal microglia to non-transplanted wt levels. Aβ and paired helical filament-tau were reduced (61.0% and 44.1% respectively) in BMT-recipient AD mice, which had 20.8% more retinal ganglion cell layer neurons than non-transplanted AD controls. Interestingly, aged wt BMT recipients also had significantly more neurons (25.4%) compared with non-transplanted aged wt controls. Quantitation of retinal ganglion cell layer neurons in young mice confirmed age-related retinal degeneration was mitigated by BMT. We found increased MHC class II expression in BMT-derived microglia and decreased oxidative damage in retinal ganglion cell layer neurons. Thus, BMT is neuroprotective in age-related as well as AD-related retinal degeneration, and may be a result of alterations in innate immune function and oxidative stress in BMT recipient mice.

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BMT results in reduced RGCL oxidative stress in aged wt and APPswe-PS1ΔE9 mice.A: Immunofluorescence stains for 8-OHdG (red), an indicator of oxidative stress, are shown in representative retinal cross-sections from age-matched wt (left column) or APPswe-PS1ΔE9 (right column) mice that received no BMT transplant (top row) or BMT (bottom row). 8-OHdG immunofluorescence is primarily detected in RGCL neurons in non-transplanted wt and APPswe-PS1ΔE9 mice in a diffuse, perikaryal pattern. However, only focal, punctate immunostaining was observed in retinas from wt and APPswe-PS1ΔE9 mice that received BMT. Arrows indicate regions highlighted in insets. Scale bar  = 20 μm. B: Quantification of 8-OHdG immunofluorescence relative intensity in RGCL neurons confirmed a significant reduction in 8-OHdG immunostaining in wt and APPswe-PS1ΔE9 mice that received BMT compared with non-transplanted controls, respectively. ***P<0.001, n = 6–10, two-way ANOVA followed by Bonferroni post test.
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pone-0064246-g008: BMT results in reduced RGCL oxidative stress in aged wt and APPswe-PS1ΔE9 mice.A: Immunofluorescence stains for 8-OHdG (red), an indicator of oxidative stress, are shown in representative retinal cross-sections from age-matched wt (left column) or APPswe-PS1ΔE9 (right column) mice that received no BMT transplant (top row) or BMT (bottom row). 8-OHdG immunofluorescence is primarily detected in RGCL neurons in non-transplanted wt and APPswe-PS1ΔE9 mice in a diffuse, perikaryal pattern. However, only focal, punctate immunostaining was observed in retinas from wt and APPswe-PS1ΔE9 mice that received BMT. Arrows indicate regions highlighted in insets. Scale bar  = 20 μm. B: Quantification of 8-OHdG immunofluorescence relative intensity in RGCL neurons confirmed a significant reduction in 8-OHdG immunostaining in wt and APPswe-PS1ΔE9 mice that received BMT compared with non-transplanted controls, respectively. ***P<0.001, n = 6–10, two-way ANOVA followed by Bonferroni post test.

Mentions: Whether pro- or anti-inflammatory, microglia activation is a complex process which depends on selective elaboration of a diverse repertoire of cytokines, chemokines, proteases, and prostanoids that can be neuroprotective or neurotoxic depending on the subset of molecules secreted. Because our primary endpoint, immunohistology, required fixed tissues, we were unable to quantitatively assay for the aforementioned molecules, and immunostains were uninformative (data not shown). However, a ubiquitous endpoint of classical, pro-inflammatory innate immune activation is oxidative damage mediated by elaboration of microglial ROS. Alternatively, microglia contain multiple antioxidative defense mechanisms including abundant glutathione, superoxide dismutase, catalase, and other enzymes that can mitigate oxidative stress [61]. It is well-accepted that age-related neurodegeneration may be due to increased DNA damage caused by oxidative stress with age [62]. In order to determine the effects of BMT on oxidative stress in retinal neurons, we analyzed retinal sections for the presence of 8-hydroxydeoxyguanosine (8-OHdG), an indicator of oxidative DNA damage, in aged (13-month-old) wt and APPswe-PS1ΔE9 non-transplanted and BMT recipient mice. 8-OHdG is prominent in RGCL neurons in control wt and APPswe-PS1ΔE9 retina, but was markedly decreased in RGCL neurons of BMT recipient mice (Fig. 8A). Quantitative analysis revealed significantly reduced 8-OHdG relative intensity in RGCL of wt and APPswe-PS1ΔE9 mice received BMT compared with non-transplanted age-matched controls, respectively (Fig. 8B, P<0.001, two way ANONA using Bonferroni post hoc test). We interpret this data to indicate that BMT shifted aging retina from a neurotoxic, pro-inflammatory, oxidative environment to a neuroprotective, alternatively activated, pro-phagocytic, and anti-oxidative milieu that resulted in reduced Aβ and preservation of RGCL neurons.


Suppressed retinal degeneration in aged wild type and APPswe/PS1ΔE9 mice by bone marrow transplantation.

Yang Y, Shiao C, Hemingway JF, Jorstad NL, Shalloway BR, Chang R, Keene CD - PLoS ONE (2013)

BMT results in reduced RGCL oxidative stress in aged wt and APPswe-PS1ΔE9 mice.A: Immunofluorescence stains for 8-OHdG (red), an indicator of oxidative stress, are shown in representative retinal cross-sections from age-matched wt (left column) or APPswe-PS1ΔE9 (right column) mice that received no BMT transplant (top row) or BMT (bottom row). 8-OHdG immunofluorescence is primarily detected in RGCL neurons in non-transplanted wt and APPswe-PS1ΔE9 mice in a diffuse, perikaryal pattern. However, only focal, punctate immunostaining was observed in retinas from wt and APPswe-PS1ΔE9 mice that received BMT. Arrows indicate regions highlighted in insets. Scale bar  = 20 μm. B: Quantification of 8-OHdG immunofluorescence relative intensity in RGCL neurons confirmed a significant reduction in 8-OHdG immunostaining in wt and APPswe-PS1ΔE9 mice that received BMT compared with non-transplanted controls, respectively. ***P<0.001, n = 6–10, two-way ANOVA followed by Bonferroni post test.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3672108&req=5

pone-0064246-g008: BMT results in reduced RGCL oxidative stress in aged wt and APPswe-PS1ΔE9 mice.A: Immunofluorescence stains for 8-OHdG (red), an indicator of oxidative stress, are shown in representative retinal cross-sections from age-matched wt (left column) or APPswe-PS1ΔE9 (right column) mice that received no BMT transplant (top row) or BMT (bottom row). 8-OHdG immunofluorescence is primarily detected in RGCL neurons in non-transplanted wt and APPswe-PS1ΔE9 mice in a diffuse, perikaryal pattern. However, only focal, punctate immunostaining was observed in retinas from wt and APPswe-PS1ΔE9 mice that received BMT. Arrows indicate regions highlighted in insets. Scale bar  = 20 μm. B: Quantification of 8-OHdG immunofluorescence relative intensity in RGCL neurons confirmed a significant reduction in 8-OHdG immunostaining in wt and APPswe-PS1ΔE9 mice that received BMT compared with non-transplanted controls, respectively. ***P<0.001, n = 6–10, two-way ANOVA followed by Bonferroni post test.
Mentions: Whether pro- or anti-inflammatory, microglia activation is a complex process which depends on selective elaboration of a diverse repertoire of cytokines, chemokines, proteases, and prostanoids that can be neuroprotective or neurotoxic depending on the subset of molecules secreted. Because our primary endpoint, immunohistology, required fixed tissues, we were unable to quantitatively assay for the aforementioned molecules, and immunostains were uninformative (data not shown). However, a ubiquitous endpoint of classical, pro-inflammatory innate immune activation is oxidative damage mediated by elaboration of microglial ROS. Alternatively, microglia contain multiple antioxidative defense mechanisms including abundant glutathione, superoxide dismutase, catalase, and other enzymes that can mitigate oxidative stress [61]. It is well-accepted that age-related neurodegeneration may be due to increased DNA damage caused by oxidative stress with age [62]. In order to determine the effects of BMT on oxidative stress in retinal neurons, we analyzed retinal sections for the presence of 8-hydroxydeoxyguanosine (8-OHdG), an indicator of oxidative DNA damage, in aged (13-month-old) wt and APPswe-PS1ΔE9 non-transplanted and BMT recipient mice. 8-OHdG is prominent in RGCL neurons in control wt and APPswe-PS1ΔE9 retina, but was markedly decreased in RGCL neurons of BMT recipient mice (Fig. 8A). Quantitative analysis revealed significantly reduced 8-OHdG relative intensity in RGCL of wt and APPswe-PS1ΔE9 mice received BMT compared with non-transplanted age-matched controls, respectively (Fig. 8B, P<0.001, two way ANONA using Bonferroni post hoc test). We interpret this data to indicate that BMT shifted aging retina from a neurotoxic, pro-inflammatory, oxidative environment to a neuroprotective, alternatively activated, pro-phagocytic, and anti-oxidative milieu that resulted in reduced Aβ and preservation of RGCL neurons.

Bottom Line: BMT resulted in near complete replacement of host retinal microglia with BMT-derived cells and normalized total AD retinal microglia to non-transplanted wt levels.Interestingly, aged wt BMT recipients also had significantly more neurons (25.4%) compared with non-transplanted aged wt controls.We found increased MHC class II expression in BMT-derived microglia and decreased oxidative damage in retinal ganglion cell layer neurons.

View Article: PubMed Central - PubMed

Affiliation: Department of Pathology, University of Washington, Seattle, Washington, USA.

ABSTRACT
Alzheimer's disease (AD) is an age-related condition characterized by accumulation of neurotoxic amyloid β peptides (Aβ) in brain and retina. Because bone marrow transplantation (BMT) results in decreased cerebral Aβ in experimental AD, we hypothesized that BMT would mitigate retinal neurotoxicity through decreased retinal Aβ. To test this, we performed BMT in APPswe/PS1ΔE9 double transgenic mice using green fluorescent protein expressing wild type (wt) mice as marrow donors. We first examined retinas from control, non-transplanted, aged AD mice and found a two-fold increase in microglia compared with wt mice, prominent inner retinal Aβ and paired helical filament-tau, and decreased retinal ganglion cell layer neurons. BMT resulted in near complete replacement of host retinal microglia with BMT-derived cells and normalized total AD retinal microglia to non-transplanted wt levels. Aβ and paired helical filament-tau were reduced (61.0% and 44.1% respectively) in BMT-recipient AD mice, which had 20.8% more retinal ganglion cell layer neurons than non-transplanted AD controls. Interestingly, aged wt BMT recipients also had significantly more neurons (25.4%) compared with non-transplanted aged wt controls. Quantitation of retinal ganglion cell layer neurons in young mice confirmed age-related retinal degeneration was mitigated by BMT. We found increased MHC class II expression in BMT-derived microglia and decreased oxidative damage in retinal ganglion cell layer neurons. Thus, BMT is neuroprotective in age-related as well as AD-related retinal degeneration, and may be a result of alterations in innate immune function and oxidative stress in BMT recipient mice.

Show MeSH
Related in: MedlinePlus