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Intervention with an erythropoietin-derived peptide protects against neuroglial and vascular degeneration during diabetic retinopathy.

McVicar CM, Hamilton R, Colhoun LM, Gardiner TA, Brines M, Cerami A, Stitt AW - Diabetes (2011)

Bottom Line: In the diabetic retina, Müller glial expression of glial fibrillary acidic protein was increased when compared with nondiabetic controls, but pHBSP significantly reduced this stress-related response (P < 0.001).CD11b+ microglia and proinflammatory cytokines were elevated in diabetic retina responses, and some of these responses were attenuated by pHBSP (P < 0.01-0.001). pHBSP significantly reduced diabetes-linked DNA damage as determined by 8-hydroxydeoxyguanosine and transferase-mediated dUTP nick-end labeling positivity and also prevented acellular capillary formation (P < 0.05).In OIR, pHBSP had no effect on preretinal neovascularization at any dose.

View Article: PubMed Central - PubMed

Affiliation: Centre for Vision and Vascular Science, Queen’s University Belfast, Belfast, Northern Ireland, UK.

ABSTRACT

Objective: Erythropoietin (EPO) may be protective for early stage diabetic retinopathy, although there are concerns that it could exacerbate retinal angiogenesis and thrombosis. A peptide based on the EPO helix-B domain (helix B-surface peptide [pHBSP]) is nonerythrogenic but retains tissue-protective properties, and this study evaluates its therapeutic potential in diabetic retinopathy.

Research design and methods: After 6 months of streptozotocin-induced diabetes, rats (n = 12) and age-matched nondiabetic controls (n = 12) were evenly split into pHBSP and scrambled peptide groups and injected daily (10 μg/kg per day) for 1 month. The retina was investigated for glial dysfunction, microglial activation, and neuronal DNA damage. The vasculature was dual stained with isolectin and collagen IV. Retinal cytokine expression was quantified using real-time RT-PCR. In parallel, oxygen-induced retinopathy (OIR) was used to evaluate the effects of pHBSP on retinal ischemia and neovascularization (1-30 μg/kg pHBSP or control peptide).

Results: pHBSP or scrambled peptide treatment did not alter hematocrit. In the diabetic retina, Müller glial expression of glial fibrillary acidic protein was increased when compared with nondiabetic controls, but pHBSP significantly reduced this stress-related response (P < 0.001). CD11b+ microglia and proinflammatory cytokines were elevated in diabetic retina responses, and some of these responses were attenuated by pHBSP (P < 0.01-0.001). pHBSP significantly reduced diabetes-linked DNA damage as determined by 8-hydroxydeoxyguanosine and transferase-mediated dUTP nick-end labeling positivity and also prevented acellular capillary formation (P < 0.05). In OIR, pHBSP had no effect on preretinal neovascularization at any dose.

Conclusions: Treatment with an EPO-derived peptide after diabetes is fully established can significantly protect against neuroglial and vascular degenerative pathology without altering hematocrit or exacerbating neovascularization. These findings have therapeutic implications for disorders such as diabetic retinopathy.

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pHBSP prevents diabetes-related GFAP expression in Müller cells. Retinal sections were processed for GFAP immunoreactivity and assessed by confocal microscopy. Cntl, control; Sc, scrambled pHBSP; and Db, diabetic. A: Bar chart shows the numbers of GFAP-positive fibers crossing the IPL and INL, which is significantly increased in diabetic rats receiving scrambled peptide when compared with nondiabetic controls (*P < 0.05). pHBSP prevented the diabetes-related increase in GFAP, and there was no significant difference between this group and the nondiabetic groups. Data are mean ± SEM; n = 6 per group. B–E: Retinae from nondiabetic and diabetic groups treated with pHBSP or scrambled peptide exhibit GFAP immunoreactivity within astrocytes and a subpopulation of Müller cells. More extensive GFAP was observed in the Müller cells crossing the IPL and INL (depicted by dashed line) in the diabetic animals that received the scrambled peptide. This was reduced in the diabetic animals receiving the pHBSP peptide. (A high-quality digital representation of this figure is available in the online issue.)
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Figure 2: pHBSP prevents diabetes-related GFAP expression in Müller cells. Retinal sections were processed for GFAP immunoreactivity and assessed by confocal microscopy. Cntl, control; Sc, scrambled pHBSP; and Db, diabetic. A: Bar chart shows the numbers of GFAP-positive fibers crossing the IPL and INL, which is significantly increased in diabetic rats receiving scrambled peptide when compared with nondiabetic controls (*P < 0.05). pHBSP prevented the diabetes-related increase in GFAP, and there was no significant difference between this group and the nondiabetic groups. Data are mean ± SEM; n = 6 per group. B–E: Retinae from nondiabetic and diabetic groups treated with pHBSP or scrambled peptide exhibit GFAP immunoreactivity within astrocytes and a subpopulation of Müller cells. More extensive GFAP was observed in the Müller cells crossing the IPL and INL (depicted by dashed line) in the diabetic animals that received the scrambled peptide. This was reduced in the diabetic animals receiving the pHBSP peptide. (A high-quality digital representation of this figure is available in the online issue.)

Mentions: In the nondiabetic retina, GFAP was localized to the astrocytes and a population of retinal Müller glia (Fig. 2A and B). This was typical of the GFAP staining pattern in aging rat retina (28). Diabetes induced a strong upregulation of this protein in both astrocytes and retinal Müller glia (P < 0.05). pHBSP peptide treatment of diabetic rats significantly prevented this gliosis response in Müller glia, as indicated by a reduction in the intensity of GFAP staining in the innermost retinal layers and the number of GFAP-positive fibers in the IPL (P < 0.05) (Fig. 2A and B).


Intervention with an erythropoietin-derived peptide protects against neuroglial and vascular degeneration during diabetic retinopathy.

McVicar CM, Hamilton R, Colhoun LM, Gardiner TA, Brines M, Cerami A, Stitt AW - Diabetes (2011)

pHBSP prevents diabetes-related GFAP expression in Müller cells. Retinal sections were processed for GFAP immunoreactivity and assessed by confocal microscopy. Cntl, control; Sc, scrambled pHBSP; and Db, diabetic. A: Bar chart shows the numbers of GFAP-positive fibers crossing the IPL and INL, which is significantly increased in diabetic rats receiving scrambled peptide when compared with nondiabetic controls (*P < 0.05). pHBSP prevented the diabetes-related increase in GFAP, and there was no significant difference between this group and the nondiabetic groups. Data are mean ± SEM; n = 6 per group. B–E: Retinae from nondiabetic and diabetic groups treated with pHBSP or scrambled peptide exhibit GFAP immunoreactivity within astrocytes and a subpopulation of Müller cells. More extensive GFAP was observed in the Müller cells crossing the IPL and INL (depicted by dashed line) in the diabetic animals that received the scrambled peptide. This was reduced in the diabetic animals receiving the pHBSP peptide. (A high-quality digital representation of this figure is available in the online issue.)
© Copyright Policy - creative-commons
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3198080&req=5

Figure 2: pHBSP prevents diabetes-related GFAP expression in Müller cells. Retinal sections were processed for GFAP immunoreactivity and assessed by confocal microscopy. Cntl, control; Sc, scrambled pHBSP; and Db, diabetic. A: Bar chart shows the numbers of GFAP-positive fibers crossing the IPL and INL, which is significantly increased in diabetic rats receiving scrambled peptide when compared with nondiabetic controls (*P < 0.05). pHBSP prevented the diabetes-related increase in GFAP, and there was no significant difference between this group and the nondiabetic groups. Data are mean ± SEM; n = 6 per group. B–E: Retinae from nondiabetic and diabetic groups treated with pHBSP or scrambled peptide exhibit GFAP immunoreactivity within astrocytes and a subpopulation of Müller cells. More extensive GFAP was observed in the Müller cells crossing the IPL and INL (depicted by dashed line) in the diabetic animals that received the scrambled peptide. This was reduced in the diabetic animals receiving the pHBSP peptide. (A high-quality digital representation of this figure is available in the online issue.)
Mentions: In the nondiabetic retina, GFAP was localized to the astrocytes and a population of retinal Müller glia (Fig. 2A and B). This was typical of the GFAP staining pattern in aging rat retina (28). Diabetes induced a strong upregulation of this protein in both astrocytes and retinal Müller glia (P < 0.05). pHBSP peptide treatment of diabetic rats significantly prevented this gliosis response in Müller glia, as indicated by a reduction in the intensity of GFAP staining in the innermost retinal layers and the number of GFAP-positive fibers in the IPL (P < 0.05) (Fig. 2A and B).

Bottom Line: In the diabetic retina, Müller glial expression of glial fibrillary acidic protein was increased when compared with nondiabetic controls, but pHBSP significantly reduced this stress-related response (P < 0.001).CD11b+ microglia and proinflammatory cytokines were elevated in diabetic retina responses, and some of these responses were attenuated by pHBSP (P < 0.01-0.001). pHBSP significantly reduced diabetes-linked DNA damage as determined by 8-hydroxydeoxyguanosine and transferase-mediated dUTP nick-end labeling positivity and also prevented acellular capillary formation (P < 0.05).In OIR, pHBSP had no effect on preretinal neovascularization at any dose.

View Article: PubMed Central - PubMed

Affiliation: Centre for Vision and Vascular Science, Queen’s University Belfast, Belfast, Northern Ireland, UK.

ABSTRACT

Objective: Erythropoietin (EPO) may be protective for early stage diabetic retinopathy, although there are concerns that it could exacerbate retinal angiogenesis and thrombosis. A peptide based on the EPO helix-B domain (helix B-surface peptide [pHBSP]) is nonerythrogenic but retains tissue-protective properties, and this study evaluates its therapeutic potential in diabetic retinopathy.

Research design and methods: After 6 months of streptozotocin-induced diabetes, rats (n = 12) and age-matched nondiabetic controls (n = 12) were evenly split into pHBSP and scrambled peptide groups and injected daily (10 μg/kg per day) for 1 month. The retina was investigated for glial dysfunction, microglial activation, and neuronal DNA damage. The vasculature was dual stained with isolectin and collagen IV. Retinal cytokine expression was quantified using real-time RT-PCR. In parallel, oxygen-induced retinopathy (OIR) was used to evaluate the effects of pHBSP on retinal ischemia and neovascularization (1-30 μg/kg pHBSP or control peptide).

Results: pHBSP or scrambled peptide treatment did not alter hematocrit. In the diabetic retina, Müller glial expression of glial fibrillary acidic protein was increased when compared with nondiabetic controls, but pHBSP significantly reduced this stress-related response (P < 0.001). CD11b+ microglia and proinflammatory cytokines were elevated in diabetic retina responses, and some of these responses were attenuated by pHBSP (P < 0.01-0.001). pHBSP significantly reduced diabetes-linked DNA damage as determined by 8-hydroxydeoxyguanosine and transferase-mediated dUTP nick-end labeling positivity and also prevented acellular capillary formation (P < 0.05). In OIR, pHBSP had no effect on preretinal neovascularization at any dose.

Conclusions: Treatment with an EPO-derived peptide after diabetes is fully established can significantly protect against neuroglial and vascular degenerative pathology without altering hematocrit or exacerbating neovascularization. These findings have therapeutic implications for disorders such as diabetic retinopathy.

Show MeSH
Related in: MedlinePlus