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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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Related in: MedlinePlus

pHBSP reduces retinal hypoxia and VEGF mRNA expression. A: VEGF mRNA levels were reduced with pHBSP at 1, 10, and 30 μg/kg relative to the scrambled pHBSP (n = 6; ***P < 0.001). B–D: Retinal hypoxia was assessed by HP, which deposits an insoluble adduct in tissue at <10 mmHg. Retinal flat mounts at P17 show HP immunoreactivity in the ischemic regions (green), and this is reduced in area with 1 μg/kg when compared with the PBS and scrambled peptide control. The vasculature is visualized by isolectin (red). Shown is a representative retinal image for PBS, scrambled pHBSP, and 1 μg/kg of pHBSP. Data are mean ± SEM; n = 6 per group. PBS, PBS control; Sc, scrambled pHBSP. (A high-quality digital representation of this figure is available in the online issue.)
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Figure 8: pHBSP reduces retinal hypoxia and VEGF mRNA expression. A: VEGF mRNA levels were reduced with pHBSP at 1, 10, and 30 μg/kg relative to the scrambled pHBSP (n = 6; ***P < 0.001). B–D: Retinal hypoxia was assessed by HP, which deposits an insoluble adduct in tissue at <10 mmHg. Retinal flat mounts at P17 show HP immunoreactivity in the ischemic regions (green), and this is reduced in area with 1 μg/kg when compared with the PBS and scrambled peptide control. The vasculature is visualized by isolectin (red). Shown is a representative retinal image for PBS, scrambled pHBSP, and 1 μg/kg of pHBSP. Data are mean ± SEM; n = 6 per group. PBS, PBS control; Sc, scrambled pHBSP. (A high-quality digital representation of this figure is available in the online issue.)

Mentions: In OIR, neovascularization is driven by ischemic hypoxia (akin to that observed in long-term diabetic retinopathy in patients), so the degree of hypoxia was evaluated. Retinal HP deposition was reduced in the pHBSP-treated mice when compared with controls (Fig. 8A). The hypoxia-induced angiogenic factor VEGF was increased at the P17 time point as previously reported (27), and pHBSP decreased this expression in a dose-dependent manner (Fig. 8B).


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 reduces retinal hypoxia and VEGF mRNA expression. A: VEGF mRNA levels were reduced with pHBSP at 1, 10, and 30 μg/kg relative to the scrambled pHBSP (n = 6; ***P < 0.001). B–D: Retinal hypoxia was assessed by HP, which deposits an insoluble adduct in tissue at <10 mmHg. Retinal flat mounts at P17 show HP immunoreactivity in the ischemic regions (green), and this is reduced in area with 1 μg/kg when compared with the PBS and scrambled peptide control. The vasculature is visualized by isolectin (red). Shown is a representative retinal image for PBS, scrambled pHBSP, and 1 μg/kg of pHBSP. Data are mean ± SEM; n = 6 per group. PBS, PBS control; Sc, scrambled pHBSP. (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 8: pHBSP reduces retinal hypoxia and VEGF mRNA expression. A: VEGF mRNA levels were reduced with pHBSP at 1, 10, and 30 μg/kg relative to the scrambled pHBSP (n = 6; ***P < 0.001). B–D: Retinal hypoxia was assessed by HP, which deposits an insoluble adduct in tissue at <10 mmHg. Retinal flat mounts at P17 show HP immunoreactivity in the ischemic regions (green), and this is reduced in area with 1 μg/kg when compared with the PBS and scrambled peptide control. The vasculature is visualized by isolectin (red). Shown is a representative retinal image for PBS, scrambled pHBSP, and 1 μg/kg of pHBSP. Data are mean ± SEM; n = 6 per group. PBS, PBS control; Sc, scrambled pHBSP. (A high-quality digital representation of this figure is available in the online issue.)
Mentions: In OIR, neovascularization is driven by ischemic hypoxia (akin to that observed in long-term diabetic retinopathy in patients), so the degree of hypoxia was evaluated. Retinal HP deposition was reduced in the pHBSP-treated mice when compared with controls (Fig. 8A). The hypoxia-induced angiogenic factor VEGF was increased at the P17 time point as previously reported (27), and pHBSP decreased this expression in a dose-dependent manner (Fig. 8B).

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