Limits...
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.

Show MeSH

Related in: MedlinePlus

MHC class II is up-regulated in BMT-derived retinal microglia.A: Representative photomicrographs of microglia in the retina of a 13-month-old non-transplanted wt mouse stained with anti-Iba-1 antibody and visualized with Cy3-conjugated secondary antibody (red). The endogenous Iba-1+ microglial cells do not express detectable MHC class II by immunofluorescence stains (blue, overlay with Cy3 fluorescence) in untreated (No Tx) wt retina. B: Representative photomicrographs of retinal sections from a 13-month-old wt mouse transplanted with GFP+ BM cells. Immunofluorescence staining demonstrates that the Iba-1+ microglia (red) are almost completely derived from the BMT (green GFP+ cells). GFP+ cells were strongly immunoreactive for MHC class II (blue). The overlay of the confocal microscope images indicates co-expression of GFP (green), Iba-1 (red) and MHC class II (blue) in retina. Scale bar  = 30 μm. C: Quantification of MHC class II immunofluorescence in microglia shows significantly increased expression in BM-derived cells compared with the endogenous microglia. ***P<0.001, n = 6, student's t test. D: Confocal analysis of sections demonstrates association of BM-derived microglia (GFP+, green, arrow) and Aβ deposits (red). High magnification of inset is shown on the lower panels. Scale bar: 20 µm. E: 3D-Confocal image analysis of intracellular Aβ in BM-derived microglia. The overlay of confocal images reveals Aβ deposition (red) within GFP+ BM-derived microglia (green, arrow). High magnification of inset is shown on the right panels. Scale bar: 20 µm.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC3672108&req=5

pone-0064246-g007: MHC class II is up-regulated in BMT-derived retinal microglia.A: Representative photomicrographs of microglia in the retina of a 13-month-old non-transplanted wt mouse stained with anti-Iba-1 antibody and visualized with Cy3-conjugated secondary antibody (red). The endogenous Iba-1+ microglial cells do not express detectable MHC class II by immunofluorescence stains (blue, overlay with Cy3 fluorescence) in untreated (No Tx) wt retina. B: Representative photomicrographs of retinal sections from a 13-month-old wt mouse transplanted with GFP+ BM cells. Immunofluorescence staining demonstrates that the Iba-1+ microglia (red) are almost completely derived from the BMT (green GFP+ cells). GFP+ cells were strongly immunoreactive for MHC class II (blue). The overlay of the confocal microscope images indicates co-expression of GFP (green), Iba-1 (red) and MHC class II (blue) in retina. Scale bar  = 30 μm. C: Quantification of MHC class II immunofluorescence in microglia shows significantly increased expression in BM-derived cells compared with the endogenous microglia. ***P<0.001, n = 6, student's t test. D: Confocal analysis of sections demonstrates association of BM-derived microglia (GFP+, green, arrow) and Aβ deposits (red). High magnification of inset is shown on the lower panels. Scale bar: 20 µm. E: 3D-Confocal image analysis of intracellular Aβ in BM-derived microglia. The overlay of confocal images reveals Aβ deposition (red) within GFP+ BM-derived microglia (green, arrow). High magnification of inset is shown on the right panels. Scale bar: 20 µm.

Mentions: In agreement with previous studies [43], we found robust engraftment of BM-derived microglia in retina (Fig. 2); non-microglia lineage cells, including neurons and other glia, were uniformly of host origin. Based on this, we hypothesized that BMT-mediated neuroprotection was most likely secondary to modulation of innate immune related proteins. MHC class II expression in microglia is associated with increased Aβ clearance in APPswe-PS1ΔE9 mice [34] and is increased in BMT-derived microglia in brain (personal observation). Thus, since we found significantly reduced retinal Aβ in BMT-recipient APPswe-PS1ΔE9 mice (Fig. 3), we hypothesized that BMT-derived microglia would exhibit increased MHC class II. Immunofluorescence staining revealed weak expression in Iba-1+ cells in non-transplanted controls (Fig. 7A). However, in BMT-recipient mice, strong MHC class II expression was found in the GFP+ BM-derived cells compared with rare endogenous (GFP−) microglia (Fig. 7B). Fluorescence intensity analysis revealed significantly increased MHC class II expression in BM-derived cells compared with endogenous microglia (P<0.001, Student's t-test, Fig. 7C). MHC class II expression is dependent on phagocytosis of extracellular proteins, such as Aβ, and may be increased in a pro-inflammatory innate immune response, although evidence for this is inconsistent [60]. Confocal image analysis of adjacent sections confirmed BM-derived microglia cells contained intracellular Aβ immunoreactivity and had processes extending into immunopositive amyloid (Fig. 7D and 7E). Thus, MHC class II is up-regulated on BMT-derived microglia that contain intracellular Aβ.


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)

MHC class II is up-regulated in BMT-derived retinal microglia.A: Representative photomicrographs of microglia in the retina of a 13-month-old non-transplanted wt mouse stained with anti-Iba-1 antibody and visualized with Cy3-conjugated secondary antibody (red). The endogenous Iba-1+ microglial cells do not express detectable MHC class II by immunofluorescence stains (blue, overlay with Cy3 fluorescence) in untreated (No Tx) wt retina. B: Representative photomicrographs of retinal sections from a 13-month-old wt mouse transplanted with GFP+ BM cells. Immunofluorescence staining demonstrates that the Iba-1+ microglia (red) are almost completely derived from the BMT (green GFP+ cells). GFP+ cells were strongly immunoreactive for MHC class II (blue). The overlay of the confocal microscope images indicates co-expression of GFP (green), Iba-1 (red) and MHC class II (blue) in retina. Scale bar  = 30 μm. C: Quantification of MHC class II immunofluorescence in microglia shows significantly increased expression in BM-derived cells compared with the endogenous microglia. ***P<0.001, n = 6, student's t test. D: Confocal analysis of sections demonstrates association of BM-derived microglia (GFP+, green, arrow) and Aβ deposits (red). High magnification of inset is shown on the lower panels. Scale bar: 20 µm. E: 3D-Confocal image analysis of intracellular Aβ in BM-derived microglia. The overlay of confocal images reveals Aβ deposition (red) within GFP+ BM-derived microglia (green, arrow). High magnification of inset is shown on the right panels. Scale bar: 20 µm.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3672108&req=5

pone-0064246-g007: MHC class II is up-regulated in BMT-derived retinal microglia.A: Representative photomicrographs of microglia in the retina of a 13-month-old non-transplanted wt mouse stained with anti-Iba-1 antibody and visualized with Cy3-conjugated secondary antibody (red). The endogenous Iba-1+ microglial cells do not express detectable MHC class II by immunofluorescence stains (blue, overlay with Cy3 fluorescence) in untreated (No Tx) wt retina. B: Representative photomicrographs of retinal sections from a 13-month-old wt mouse transplanted with GFP+ BM cells. Immunofluorescence staining demonstrates that the Iba-1+ microglia (red) are almost completely derived from the BMT (green GFP+ cells). GFP+ cells were strongly immunoreactive for MHC class II (blue). The overlay of the confocal microscope images indicates co-expression of GFP (green), Iba-1 (red) and MHC class II (blue) in retina. Scale bar  = 30 μm. C: Quantification of MHC class II immunofluorescence in microglia shows significantly increased expression in BM-derived cells compared with the endogenous microglia. ***P<0.001, n = 6, student's t test. D: Confocal analysis of sections demonstrates association of BM-derived microglia (GFP+, green, arrow) and Aβ deposits (red). High magnification of inset is shown on the lower panels. Scale bar: 20 µm. E: 3D-Confocal image analysis of intracellular Aβ in BM-derived microglia. The overlay of confocal images reveals Aβ deposition (red) within GFP+ BM-derived microglia (green, arrow). High magnification of inset is shown on the right panels. Scale bar: 20 µm.
Mentions: In agreement with previous studies [43], we found robust engraftment of BM-derived microglia in retina (Fig. 2); non-microglia lineage cells, including neurons and other glia, were uniformly of host origin. Based on this, we hypothesized that BMT-mediated neuroprotection was most likely secondary to modulation of innate immune related proteins. MHC class II expression in microglia is associated with increased Aβ clearance in APPswe-PS1ΔE9 mice [34] and is increased in BMT-derived microglia in brain (personal observation). Thus, since we found significantly reduced retinal Aβ in BMT-recipient APPswe-PS1ΔE9 mice (Fig. 3), we hypothesized that BMT-derived microglia would exhibit increased MHC class II. Immunofluorescence staining revealed weak expression in Iba-1+ cells in non-transplanted controls (Fig. 7A). However, in BMT-recipient mice, strong MHC class II expression was found in the GFP+ BM-derived cells compared with rare endogenous (GFP−) microglia (Fig. 7B). Fluorescence intensity analysis revealed significantly increased MHC class II expression in BM-derived cells compared with endogenous microglia (P<0.001, Student's t-test, Fig. 7C). MHC class II expression is dependent on phagocytosis of extracellular proteins, such as Aβ, and may be increased in a pro-inflammatory innate immune response, although evidence for this is inconsistent [60]. Confocal image analysis of adjacent sections confirmed BM-derived microglia cells contained intracellular Aβ immunoreactivity and had processes extending into immunopositive amyloid (Fig. 7D and 7E). Thus, MHC class II is up-regulated on BMT-derived microglia that contain intracellular Aβ.

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